Showing papers on "Ruby laser published in 1985"
TL;DR: In this article, the results of a preliminary study of the mass spectrometry of solid samples using a ruby laser to ablate the sample into an inductively coupled plasma (ICP) source mass analyzer were described.
Abstract: The results are described of a preliminary study of the mass spectrometry of solid samples using a ruby laser to ablate the sample into an inductively coupled plasma (ICP) source mass spectrometer. Standard rock samples were used, pelletted with a binder into the form of a disc. Some 200 ablation pits could be accommodated on each sample. Laser pulse energies of 0.3–1 J were used in the fixed Q mode and the ablated material transferred from the ablation cell into the plasma torch by means of the plasma injector gas flow. The mass spectrometer was used in the fixed ion mode using mean ion current detection to evaluate the reproducibility of successive pulses on major constituents and in the scanning mode at the rate of 10 scans s–1 to produce spectra using mean current detection for major elements and pulse counting detection for traces. Problems were experienced with saturation of the detection system in both the mean current and pulse counting modes owing to the transient nature of the sample pulse from the laser, when attempting to quantify major elements, but except where a major peak was saturated, reasonably uniform sensitivity for most elements across the mass range from 7 to 238 m/z was obtained. Isotope ratio measurements were made on lead at 29 µg g–1 and detection limits for the elements examined appear to be 10 ng g–1 or less.
505 citations
TL;DR: In this paper, a Q-switched, frequency-doubled ruby laser has been used to generate wide bandwidth ultrasonic transients in aluminum and steel plates, both longitudinal and shear waves were generated, resultant waveforms being dependent upon the irradiation conditions.
Abstract: A Q‐switched, frequency‐doubled ruby laser has been used to generate wide bandwidth ultrasonic transients in aluminum and steel plates. Both longitudinal and shear waves were generated, resultant waveforms being dependent upon the irradiation conditions. Various designs of electromagneticacoustic transducers were then used to detect these waveforms at the opposite side of the plate. The result is a method of ultrasonic inspection with potential in noncontact applications.
29 citations
Patent•
04 Oct 1985
TL;DR: In this paper, a train of light pulses are focussed by optics onto a workpiece and a computer operates the laser to drill a small pilot hole in the workpiece using a group of varying pulses.
Abstract: Apparatus and a method for drilling precision holes in a variety of materials. The apparatus uses a ruby laser to produce a train of light pulses which are focussed by optics onto a workpiece. Each of the pulse in the train can be controlled in peak energy, duration and shape independently from the other pulses in the train and the spot size and shape of each pulse at the workpiece can also be independently controlled. In accordance with the method, a computer operates the laser to drill a small pilot hole in the workpiece using a group of varying pulses. The pilot hole is then widened and reamed with the laser to the final size. On multilayer workpieces, multiple pulses with different pulse width, energy and spatial shape are used at each stage of the hole to prevent workpiece damage, yet allow drilling at reasonable speeds.
25 citations
TL;DR: In this article, a pulsed ruby laser was used to measure the variation of the surface reflectivity during laser irradiation and the melting depth was measured after repetitive irradiations in order to induce diffusion of dopants to the maximum melt depth.
Abstract: Using a pulsed ruby laser (λ=0.69 μm, FWHM=20ns) we have measured the variation of the surface reflectivity during laser irradiation. The melting depth has been measured after repetitive irradiations in order to induce diffusion of dopants to the maximum melt depth. Agreement with thermal model is found. Experimental measurements of time-resolved reflectivity on 1000 Aa-Si onc-Si are explained with the thermal model introducing a low thermal conductivity of 0.002 cal/(cm · s · K) in amorphous silicon.
19 citations
TL;DR: The temporal growth rates and saturation of stimulated Brillouin scattering in a CO/sub 2/-laser--irradiated plasma are investigated by picosecond Thomson scattering of ruby laser light and backscatter spectroscopy and are consistent with theoretical predictions.
Abstract: Growth rates and saturation of stimulated Brillouin scattering in a ${\mathrm{CO}}_{2}$-laser--irradiated plasma are investigated by picosecond Thomson scattering of ruby laser light and backscatter spectroscopy. The temporal growth rates are found to be consistent with theoretical predictions. The ion acoustic waves saturate at a fluctuation amplitude of l20% and subsequently show a modulated temporal behavior, as well as sidebands in the backscatter spectra consistent with saturation by strong ion trapping.
16 citations
TL;DR: In this paper, the authors measured the reflection coefficient of a target surface screened by a plasma and subjected to laser radiation with peak power density 230 MW/cm2 and found that the reflection coefficients in vacuum remained constant during a laser pulse and it was equal to the value obtained below the plasma formation threshold.
Abstract: Measurements of the reflection coefficient of a target–plasma system and of the optical thickness of the plasma were used to find the reflection coefficient of a target surface screened by a plasma and subjected to laser radiation with peak power density 230 MW/cm2. The target reflection coefficient in vacuum remained constant during a laser pulse and it was equal to the value obtained below the plasma formation threshold. In air the reflection coefficient fell to 0.23 because of the formation of a geometrically thin absorbing plasma layer on the target surface. This major difference between the behavior of the reflection coefficient of the target surface in vacuum and in air was responsible for the difference between the thermal coupling coefficients in these two cases.
16 citations
TL;DR: In this paper, the design and operation of an optimized version of a Q-switched, mode-locked and cavity-dumped ruby-laser oscillator is described.
Abstract: We report on the design and operation of an optimized version of a Q‐switched, mode‐locked, and cavity‐dumped ruby‐laser oscillator. The modulator window is much narrower than that assumed in conventional active mode‐lock theory, and is shown to yield much shorter pulses than the latter in cases where the number of round trips is restricted. To allow a high‐power pulse (≊1 GW) to evolve in the oscillator, and to allow simple synchronization to a (∼100 ns fixed delay) CO2 laser, a limit of 23 round trips was chosen, but similar limits may be imposed by lasers having short‐gain duration as in an excimer laser. Details are given on the single spark gap switching element and Pockels cells, with an analysis of their expected switching speeds, in order to establish the effectiveness of the modulator, as compared to conventional sinusoidally driven active mode lockers. Single pulses of 50–70 mJ are reliably cavity‐dumped after only 100‐ns delay (23 round trips) with pulse length adjustable from 50–100 ps with ±5‐ps stability. Relative timing between the main (CO2) and probe (ruby) pulses allows a measurement accuracy of ±50 ps to be attained.
15 citations
TL;DR: In this paper, a Q-switched, frequency doubled ruby laser has been used to generate ultrasonic transients in both metals and water, at a wavelength of 347 nm in the UV.
Abstract: A Q‐switched, frequency doubled ruby laser has been used to generate ultrasonic transients in both metals and water. The laser source delivered multimode pulses, of 30‐ns duration and energy ⩽200 mJ, at a wavelength of 347 nm in the UV. Displacements generated in metal plates were detected by wideband capacitance transducers, and compared to wave propagation theory. Thermoelastic, ablative, and modified surface sources were examined, and a good correlation between experiment and theory obtained. In addition, wideband directivity patterns in aluminum were obtained for the thermoelastic source. Thermal generation in water with a cylindrical geometry was also examined, and the expected dipolar pressure transients recorded. It was shown that their duration was a function of the multimode laser beam diameter over the 1.5‐ to 4‐mm range.
12 citations
TL;DR: In this paper, a passively mode-locked ruby laser oscillator with two saturable absorber cells was described, which, towards the end of the pulse train, generates picosecond pulses of about 3 ps FWHM upon weak pedestals approximately 40 ps wide.
11 citations
TL;DR: Raman spectroscopy has been used to characterize carbon-doped silicon samples prepared by ion implantation and pulsed laser annealing as discussed by the authors, and it has been shown that it has sufficient sensitivity to detect striated carbon distributions in as-grown commercial silicon.
Abstract: Raman spectroscopy is used to characterize carbon-doped silicon samples prepared by ion implantation and pulsed laser annealing. Sharp lines are observed in the Raman spectra due to the 12C local mode at 604±1 cm-1 and the 13C local mode at 586±1 cm-1. Identical spectra are obtained from a given carbon implant whether it is annealed using a 10 ns pulsed ruby laser or the significantly longer pulse of an R6G dye laser. It is shown that Raman spectroscopy has sufficient sensitivity to detect striated carbon distributions in as-grown commercial silicon. Finally, at high carbon density, where the local modes begin to broaden in the implanted and laser-annealed samples, a disorder-induced first-order Raman spectrum is observed produced by the mass defect of the substitutional carbon.
10 citations
TL;DR: In premixed laminar methane–air flames time- and space-resolved oxygen concentration and temperature measurements have been performing using a Q-switched ruby laser Raman probe, good agreement was found with comparative suction probe concentration measurements and with additionally performed optical temperature measurements.
Abstract: In premixed laminar methane–air flames time- and space-resolved oxygen concentration and temperature measurements have been performing using a Q-switched ruby laser Raman probe. Concentration and temperature have been evaluated from selected intensities of the Raman Stokes vibrational Q-branch. Good agreement was found with comparative suction probe concentration measurements and with additionally performed optical (Rayleigh, cw laser Raman) temperature measurements. For fuel-lean flames with various equivalence ratios the pulsed laser Raman probe could be used for controlling stoichiometric flame conditions. Selecting three different narrowband interference filters appropriately, a simultaneous determination of vibrational and rotational temperatures seems possible.
TL;DR: In this article, the authors performed DLTS measurements for Au/n-CdTe junctions which were formed on surfaces irradiated by a pulsed ruby laser and showed that the irradiation of more than 0.3 J/cm2 energy density improved the Schottky junction and ohmic contact.
Abstract: DLTS measurements were carried out for Au/n-CdTe junctions which were formed on surfaces irradiated by a pulsed ruby laser. Electron trap levels at 0.65 eV and 0.83 eV below the conduction band were induced in high concentration by the irradiation of more than 0.8 J/cm2 energy density. The irradiation of 0.3 J/cm2 improved the characteristics of Schottky junction of Au/n-CdTe and ohmic contact of In/n-CdTe.
TL;DR: In this paper, the authors reported the generation of ultra-short pulses in the VUV (λ = 173.5 nm) using a four-wave mixing technique in magnesium vapour.
TL;DR: In this paper, the ground-state dissociation energies of K2, Rb2, and Cs2 were determined directly from the time of flight of the dissociation fragment pairs and from the use of retarding potentials.
Abstract: Multiphoton ionization of K2, Rb2, and Cs2 in beam conditions by pulsed ruby laser radiation (λ = 6946.0 A, pulse duration ~10 ns) and subsequent dissociation of the dimer ions by one or more additional photons have been observed. Ground-state dissociation energies of these ionic species have been determined directly from the time of flight of the dissociation fragment pairs, and from the use of retarding potentials, to be , , and . These observed values have been compared with the theoretical and experimental work of other authors. Our results for the and ions are the first direct measurements of their ground-state dissociation energies. The effect of laser polarization on the dissociation mechanism has also been experimentally investigated.
TL;DR: In this paper, two flat oxyacetylene flames focus a pulsed ruby laser which burns a hole in a polythene target, and the formation of two types of fringes, fine and coarse, is observed and explained.
TL;DR: In this article, high-pressure gaseous argon at pressures up to 200 atm was irradiated by a ruby laser to study the physical properties of the laser-produced plasma.
Abstract: High-pressure gaseous argon at pressures up to 200 atm was irradiated by a ruby laser to study the physical properties of the laser-produced plasma. High-density plasmas with an electron density of the order of 1020~1021 cm-3 were obtained. At low pressure, a nearly complete ionized state was achieved, and as the gas pressure increased, the degree of ionization decreased. The electron temperature was of the order of 105 K and increased slightly with increasing pressure. The hot plasma was conical with its apex at the focal point, and the radius of the plasma depended only on the axial position. As the pressure increased, the plasma extended axially in front of and behind the focal spot. This phenomenon is interpreted as the result of a change in the refractive properties of the high-pressure gas.
01 Jan 1985
TL;DR: In this article, a modification of speckle photography allows for measuring the deflection of laser light in a flow with varying gas density, with an suitably short exposure time, as provided by a ruby laser.
Abstract: A modification of speckle photography allows for measuring the deflection of laser light in a flow with varying gas density. With an suitably short exposure time, as provided by a ruby laser, the deflection can be measured in a field with fluctuating gas density. The method is demonstrated for the case of a turbulent helium jet exhausting into the ambient atmosphere.
TL;DR: The collective acceleration of heavy ions (C, Al, Fe) from a laser produced plasma to energies in excess of 10 MeV/amu has been observed experimentally in this paper.
Abstract: The collective acceleration of heavy ions (C, Al, Fe) from a laser produced plasma to energies in excess of 10 MeV/amu has been observed experimentally. In the experiments, an intense relativistic electron beam (1.2 MeV, 30 kA, 30 ns) is injected through an anode aperture into a downstream drift region. Ions to be accelerated are produced by firing a Q‐switched ruby laser (0.3–15 J, 15 ns) at a target material located immediately downstream of the anode aperture. Accelerated ion energies are measured by time of flight, range‐energy, and Thomson spectrometer techniques.
TL;DR: In this article, a nonalloyed AuGe-Ni contact was formed on n+diffused layers on GaAs, which were formed on semi-insulating substrates by depositing a layer of tin-silica film and irradiating by ruby laser alone without thermal diffusion.
Abstract: Nonalloyed ohmic contacts were formed on n+diffused layers on GaAs. The n+layers were formed on semi-insulating substrates by depositing a layer of tin-silica film and irradiating by ruby laser alone without thermal diffusion. Vacuum-evaporated AuGe-Ni contacts display low specific contact resistance ≃1.8 × 10-6Ω.cm2, without alloying.
TL;DR: In this article, the principal stress distribution in a semi-infinite plate with a rectangular hole during the propagation of a stress wave was solved using a polyester model having a partially reflecting front surface and a double-pulse Ruby laser, each pulse having an energy of 0·5 J.
TL;DR: In this article, the experimental evidence of a dimensional effect in the evolution of the energy coupling coefficient as a function of the incident energy density at the TEA-CO2 laser irradiation of copper in air and the absence of any dimensional influence on the same dependence in the case of the same samples is accounted for in terms of the supplementary energy transfer from the laser radiation the target through the intermediary of the surface electromagnetic waves propagating onto the target surface when a periodical structure is induced within the irradiation spot.
01 Jun 1985
TL;DR: In this paper, a comparison of predictions of heat flow calculations to the measured depth of melting in both crystalline and amorphous silicon has been made, and it is reported that the results are in reasonable agreement with the KrF results only if the silicon liquid phase reflectivity at 249 nm is significantly less than that obtained by extrapolation of themore-wise optical parameters from longer wavelengths.
Abstract: Pulses of radiation from a ruby laser (lambda = 693 nm, FWHM = 12 ns), a XeCl excimer laser (lambda = 308 nm, FWHM = 25 and 70 ns), and a KrF excimer laser (lambda = 248 nm, FWHM = 32 ns) have been used to induce melting of crystalline silicon and thin (<1 mum) amorphous layers of Si on crystalline silicon substrates Depths of melting in crystalline Si were measured by TEM observations of the removal of dislocation loops created by low-dose ion implantation Depths of melting of amorphous Si layers were monitored by observing the boundaries between a large polycrystalline region, assumed to form by normal melting from and resolidification back to the free surface, and a fine polycrystalline region, assumed to form by the explosive propagation inward of a thin buried liquid layer In this work we report the comparison of predictions of heat flow calculations to the measured depth of melting in both crystalline and amorphous silicon Excellent agreement is found with the Ruby and the XeCl results Reasonable agreement with the KrF results is obtained only if the silicon liquid phase reflectivity at 249 nm is significantly less than that obtained by extrapolation of themore » optical parameters from longer wavelengths« less
TL;DR: In this article, the time dependence of the etching process enhanced during pulse irradiation is analyzed and the reasons for the differences in etching rates between amorphous and single-crystal silicon are given on the basis of experimental and numerical results.
Abstract: Surfaces of single-crystal silicon wafers are amorphized by high-dose phosphorous ion implantation. These surfaces of the wafers, immersed in concentrated KOH, are laser-chemically etched by pulse irradiation of a ruby laser. Simultaneously, the remaining parts of the amorphous layer are annealed. The time dependence of the etching process enhanced during pulse irradiation is recorded and analysed. Reasons for the etching rates which differ between amorphous and single-crystal silicon are given on the basis of experimental and numerical results.
TL;DR: In this article, a homogeneously pumped intracavity Raman oscillator or amplifier was used to produce 2 ns duration second Stokes pulses with near 50% quantum efficiency using a 25 ns duration ruby laser as the pump source and compressed hydrogen as the Raman scatterer.
TL;DR: In this paper, Raman induced cavity dumping has been demonstrated theoretically and experimentally as an efficient technique of pulse compression, through intracavity stimulated Raman scattering the electromagnetic energy at a primary frequency is downconverted and extracted from a storage cavity containing the Raman medium.
Abstract: Raman induced cavity dumping has been demonstrated theoretically and experimentally as an efficient technique of pulse compression. Through intracavity stimulated Raman scattering the electromagnetic energy at a primary frequency is down-converted and extracted from a storage cavity containing the Raman medium. Several experimental set-ups have been tested, concerning oscillators and amplifiers, using different pumping techniques. Results differ slightly according to the technique used, but pulse shortenings exceeding 10 and quantum efficiencies larger than 80 per cent were obtained. This method developed in the case of a ruby laser could also be used with large power lasers of any wavelength from the ultraviolet to the far infrared.
Patent•
01 Oct 1985
TL;DR: In this article, the laser beams are irradiated on the prescribed position of the metallic film and the irradiated parts of the film are removed to form a desired pattern, which is then removed by hot stamping.
Abstract: PURPOSE: To produce display parts in an increased yield in a common stage whether the surfaces are plane or uneven by irradiating laser beams on a metallic film adhered to each resin member by hot stamping so as to form a desired pattern. CONSTITUTION: A metallic film 1 is adhered to each resin member 2 by hot stamping. Laser beams 3 having 0.2W2μm wavelength are generated from a laser beam generator such as YAG laser, secondary harmonic YAG laser, ruby laser or Ar laser. The laser beams 3 are irradiated on the prescribed position of the metallic film 1 and the irradiated parts of the film 1 are removed to form a desired pattern. COPYRIGHT: (C)1987,JPO&Japio
TL;DR: In this paper, the total Raman cross-sections of H2 and D2 for the ruby-laser wavelength of 6943 A were estimated from an experiment, where the Raman scattered light is polarized only 14% by linearly-polarized ruby laser light incident in D2.
Abstract: The Raman scattered light is polarized only 14% by linearly-polarized ruby laser light incident in D2. The total Raman cross-sections of H2 and D2 for the ruby-laser wavelength of 6943 A were estimated from an experiment. The Raman cross-section σH2 (J) of the J=2 →0 pure rotational transition for H2 was found to be 2.510-30 cm2, while σD2 (J) of the J=3 →1 pure rotational transition for D2 was 2.310-30 cm2.
TL;DR: The Single Point Thomson Scattering System as discussed by the authors uses a multipulse ruby laser to measure Te and ne up to twenty times during a JET plasma pulse, and the scattering volume is on the equatorial plane and can be relocated to any one of seven specific points on a major radius.
Abstract: The Single Point Thomson Scattering System uses a multipulse ruby laser to measure Te and ne up to twenty times during a JET plasma pulse. The scattering volume is on the equatorial plane and, between plasma pulses, can be relocated to any one of seven specific points on a major radius. The collection system employs multimirror arrays and a triple prism spectrometer is used to eliminate stray laser light and disperse the scattered light. Novel features include two optoelectronic feedback systems which maintain alignment within the laser input and the collection systems. Sensitive components are located outside the biological shield, and those inside are compatible with remote handling procedures. The entire diagnostic can be remotely controlled via the JET computer system. Initial results from the diagnostic are presented.
TL;DR: In this paper, the energy and time characteristics of the radiation under conditions of intracavity stimulated Raman scattering (STRS) conversion in hydrogen using ultrashort pulses emitted by an actively mode-locked ruby laser were investigated.
Abstract: An investigation was made of the energy and time characteristics of the radiation under conditions of intracavity stimulated Raman scattering (STRS) conversion in hydrogen using ultrashort pulses emitted by an actively mode-locked ruby laser. Dependences of the efficiency of conversion of the laser radiation to the first Stokes component on the hydrogen pressure and on the laser pumping rate were obtained. Both these dependences had a maximum. Time measurements demonstrated some narrowing of a single pulse of the first Stokes component and a decrease in the number of pulses in a train, compared with the laser radiation pulses.
TL;DR: In this article, a Q-switched ruby laser (1.5 J/pulse, 18 as in FWHM) gave a power density of about 10 10 W/cm2 on the target.
Abstract: The radiation emitted from laser-produced plasmas of tungsten, ytterbium, and samarium has been observed at different wavelengths in a range of 30-200 am by means of timeresolved spectroscopic method. A Q-switched ruby laser (1.5 J/pulse, 18 as in FWHM) gave a power density of about 10 10 W/cm2 on the target. The intensity integrated over one pulse is found to be reproducible to ±20% or better over several tens of laser shots on the single target spot. The integrated intensity and FWHM of the VUV radiation are nearly inde pendent of the target materials studied, and their dependence on the angle of incidence of the laser beam is also described.