Showing papers on "Ruby laser published in 1992"
TL;DR: This new laser system produces clinically significant fading of superficial cutaneous pigmented lesions in patients, without complications such as hypertrophic scarring or changes in the normal skin pigmentation, often seen with conventional laser systems or other therapeutic methods.
Abstract: The Q-switched ruby laser at 694 nm, a wavelength well absorbed by melanin relative to other optically absorbing structures in skin, causes highly selective destruction of pigment-laden cells. In addition, the 20-nsec pulse duration produced by this laser approximates the thermal relaxation time for
77 citations
01 Jan 1992
TL;DR: The first dental laser based on a Nd:YAG engine provides handpieces of similar size to conventional instrumentation, and being fed by a fibre-optic "cable," has the flexibility for intra-oral use that the carbon dioxide lasers, widely used in oral surgery, lack.
Abstract: Clinical lasers are of two types. Soft lasers are essentially an aid to healing, with relatively few rigorous studies available to support their use. Surgical hard lasers, however, can cut both hard and soft tissues, replacing the scalpel and drill in many areas. After initial experiments with the ruby laser, most clinicians have been using argon, carbon dioxide, and now Nd:YAG systems. The first dental laser based on a Nd:YAG engine provides handpieces of similar size to conventional instrumentation, and being fed by a fibre-optic "cable," has the flexibility for intra-oral use that the carbon dioxide lasers, widely used in oral surgery, lack. Furthermore, extensive clinical investigation has demonstrated their safety in clinical practice, and the fact that procedures can usually be performed without a local anaesthetic is obviously seen as an advantage by patients. Sterilizing as it cuts, the Nd:YAG laser promises to find uses not only in caries removal and soft tissue surgery but also in periodontics and endodontics.
75 citations
TL;DR: The successful use of the Q-switched ruby laser is reported in the treatment of two patients with the nevus of Ota, a benign facial oculocutaneous melanosis that has melanosomes lying deeply within the dermis.
Abstract: Emission of 694-nm laser energy from a Q-switched ruby laser causes photodestruction of cutaneous pigment. The 40-nanosecond pulse duration of Q-switched ruby laser light initiates specific damage to melanosomes thus allowing selective treatment of benign pigmented lesions. Nevus of Ota is a benign facial oculocutaneous melanosis that has melanosomes lying deeply within the dermis. We report the successful use of the Q-switched ruby laser in the treatment of two patients with the nevus of Ota.
75 citations
TL;DR: In this paper, a series of structure observations of hydroxyapatite (HA) films obtained by pulsed laser deposition (PLD) using a pulsed ruby laser as well as of “in situ” mass spectrometry measurements, in order to elucidate the mechanism of target ablation and film deposition.
70 citations
TL;DR: In this paper, a model based on hydrodynamic sputtering is proposed to explain the process of diamond particulate formation in pyrolytic graphite surfaces under benzene.
46 citations
TL;DR: Three patients who had labial lentigos were treated with the Q-switched ruby laser, and dramatic clearing occurred after one or two treatments with a fluence of 10 J/cm2.
Abstract: The Q-switched ruby laser causes selective damage to pigmented cells in the skin. This laser, which has a wavelength of 694 nm and a pulse duration of 40 nsec, has shown very promising results in the treatment of both amateur and professional tattoos. Less data are available on its ability to treat benign pigmented lesions of the skin. Three patients who had labial lentigos were treated with the Q-switched ruby laser, and dramatic clearing occurred after one or two treatments with a fluence of 10 J/cm 2 .
39 citations
TL;DR: In this article, the short wavelength emitting S2 excited state has been populated by a two photon absorption process using the excitation light at 695 nm of a pulsed ruby laser.
Abstract: The weak (φf 0.3) normal emission at around 700 nm originating from S1 and having a lifetime in the 4.1 to 10.6 ns range, depending on the solvent. The short wavelength emitting S2 excited state has been populated by a two photon absorption process using the excitation light at 695 nm of a pulsed ruby laser. This process is shown not to involve the triplet state but the following stepwise two photon absorption process:
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38 citations
TL;DR: In this article, the epitaxial βFeSi2 layers were irradiated by 25 ns ruby laser pulses in the energy density range 0.3-0.7 J/cm2.
Abstract: Epitaxial βFeSi2 layers thermally grown on (111) Si substrates have been irradiated by 25 ns ruby laser pulses in the energy density range 0.3–0.7 J/cm2. Rutherford backscattering analyses in combination with the channeling effect have shown that the silicide stoichiometry does not change for irradiations up to an energy density of 0.5 J/cm2, while alignment of the irradiated silicide along the [111] substrate normal direction is observed. Transmission electron diffraction in the plan view configuration showed that this silicide phase has a cubic symmetry with a lattice parameter very similar to that of Si. Diffraction patterns taken along different poles of the substrate indicated that the epitaxial phase is 180° rotated about the [111] normal direction like the B type NiSi2 and CoSi2 silicides.
36 citations
TL;DR: An attempt was made to modify the surface microstructure of a sensitized austenitic stainless steel, without affecting the bulk properties, using laser surface melting techniques as mentioned in this paper, which indicated an improvement in the intergranular corrosion resistance.
Abstract: An attempt was made to modify the surface microstructure of a sensitized austenitic stainless steel, without affecting the bulk properties, using laser surface melting techniques. AISI type 316 stainless steel specimens sensitized at 923 K for 20 hr were laser surface melted using a pulsed ruby laser at 6 J energy. Two successive pulses were given to ensure uniform melting and homogenization. The melted layers were characterized by small angle X- ray diffraction and scanning electron microscopy. Intergranular corrosion tests were carried out on the melted region as per ASTM A262 practice A (etch test) and electrochemical potentiokinetic reactivation test. The results indicated an improvement in the intergranular corrosion resistance after laser surface melting. The results are explained on the basis of homogeneous and nonsensitized microstructure obtained at the surface after laser surface melting. It is concluded that laser surface melting can be used as an in situ method to increase the life of a sensitized component by modifying the surface microstructure.
33 citations
TL;DR: Research studies on normal and pathologic tissues in and around the brain and spinal cord quickly and dramatically showed the potential for benefit to animal and human patients with experimental and naturally occurring neoplasms, burns, and decubitus ulcers.
Abstract: This contribution to the history of laser applications to neurosurgical patients gives the background against which the subsequent developments took place. It covers the important facts regarding the theoretical formulations that led to the invention of the world's first laser in 1960. This was a pulsed ruby laser, which proved lacking in desirable surgical procedures, and at high powers was shown to be damaging to vital organs, such as the brain. It could be lethal to small animals. These very early tests of laser tissue and organ interaction included studies on protein in solution, cultured cells, brain, spinal cord and their surrounding tissues, and transplantable melanomas, as well as ependymoblastomas in mice. Fortunately, the continuous wave CO2 laser came along in 1967 to replace both the pulsed ruby and neodymium-in-glass lasers. The CO2 laser was quickly seen to possess surgical properties, namely, vaporization, cutting, hemostasis, and sterilization, without additional damage at a dista...
24 citations
TL;DR: In this paper, the authors have recorded the time-resolved photoabsorption spectra of aluminium plasmas in the 50-200 AA wavelength range using the dual laser produced plasma technique (DLPP).
Abstract: The authors have recorded the time-resolved photoabsorption spectra of aluminium plasmas in the 50-200 AA wavelength range using the dual laser produced plasma technique (DLPP). Absorbing plasmas were generated by focusing the output from a pulsed dye or a Q-switched ruby laser onto an aluminium slab target. The continuum backlight was provided by irradiating a tantalum rod with the output from a time-synchronized Q-switched Nd-YAG laser. Some of the spectra were recorded with the aid of a toroidal mirror. By combining time and space resolution the authors have been able to isolate almost exclusively Al+ and record its photoabsorption spectrum. They provide an analysis of 2p to nd, (n+1)s Rydbergs in Al+ based on multiconfiguration ab initio atomic structure calculations and quantum defects for the higher members of each series. They have also observed and tentatively classified a number of members of the 2p63s2 to 2p53s3p2 doubly excited transition array.
Patent•
21 Jul 1992TL;DR: An optical filter for absorbing neodymium YAG-doubled laser radiation at 532 nanometers, comprising a polymeric matrix of transparent polycarbonate containing platinum deuteroporphyrin IX dimethyl ester, has an optical density of 1.8.
Abstract: An optical filter for absorbing neodymium YAG-doubled laser radiation at 532 nanometers, comprising a polymeric matrix of transparent polycarbonate containing platinum deuteroporphyrin IX dimethyl ester, has an optical density of 1.8 at 532 nm while having a photopic luminous visible transmission of 53.8%. Optionally, the filter may contain other additives for absorption at other laser wavelengths, such as vanadyl tetra-4-tert-butylphthalocyanine for absorption of ruby laser radiation at 694 nanometers and tris(p-diethylaminophenyl)aminium hexafluoroantimonate for absorption of neodymium YAG laser radiation at 1064 nanometers.
TL;DR: In this paper, a projected halo (or ring pattern) of blue-green light around the pump laser spot was observed on a card placed after a 5-cm-long cylindrical sample cell.
Abstract: Stimulated Raman scattering (SRS) was first observed by Woodbury and Ng [l] using a nitrobenzene Kerr shutter as the Q-switch of a ruby laser, and then identified by Eckhardt et al. [2]. If threshold requirements for the pump intensity and the interaction length were fulfilled for a given gain medium, SRS could be performed in a simple laser spectroscopy experiment of toluene, where a projected halo (or ring pattern) of blue-green light around the pump laser spot was observed on a card placed after a 5-cm-long cylindrical sample cell (see Fig. 1). A measurement of the radius of the halo as a function of distance along the pump beam path would determine its origin to be a point inside the sample cell, as shown in Fig. 2. However, the halo might disappear if a 1-cm-long cylindrical cell was substituted. Similar halos were observed for benzene over a wide range of pump laser wavelengths, from 445 to 535 nm for instance. The colors of the halos induced by different pump laser wavelengths would be sli...
TL;DR: In this article, the successful indiffusion of Ti into singlecrystalline LiNbO3 substrates was reported as a result of high-intensity ruby laser irradiation of Li NbO 3 samples coated with films of Ti of 400 A thickness and the experimental data were compared to the results of cw CO2 or Ar ion laser irradiations.
Abstract: The successful indiffusion of Ti into single‐crystalline LiNbO3 substrates is reported as a result of high‐intensity ruby laser irradiation of LiNbO3 samples coated with films of Ti of 400 A thickness. The experimental data are compared to the results of cw CO2 or Ar ion laser irradiations. We conclude that the Ti indiffusion process starts with the oxidation of Ti and continues in a liquid phase.
01 Nov 1992
TL;DR: In this article, a multi-frame image converter camera with a laser illuminator was developed to produce sequential photographs of fast phenomena with very high resolution, including the initial formation and early time history of high velocity shaped charge jets.
Abstract: By combining the attributes of electro-optic shuttering and pulsed laser illumination in a large format camera system, we have developed a multi-frame image converter camera with a laser illuminator that produces sequential photographs of fast phenomena with very high resolution. The combination of the large size image plane (75 mm), short exposure time per frame (minimum 12 - 15 ns), and monochromatic laser illumination provides clear, sharp, front-lit images of surfaces and shapes with no degradation by luminous air shocks or motion blur. The unique modular design of the camera and the laser allow for a variety of configurations and applications. The current camera system produces eight independent pictures or four stereo pairs. A Q-switched ruby laser with multiple pulse capability provides individual illumination for each frame. This system has photographed a variety of fast phenomena including the first stereo sequential photographs of the initial formation and early time history of high velocity shaped-charge jets.
TL;DR: Raman scattering and point contact current-voltage (PCIV) measurements were used as characterization tools of tin-diffused GaAs layers in this paper, where the diffusion was induced by irradiating GaAs substrates covered with thin tin layers single pulses of a ruby laser.
Abstract: Raman scattering and point contact current-voltage (PCIV) measurements were used as characterization tools of tin-diffused GaAs layers. Diffusion was induced by irradiating GaAs substrates covered with thin tin layers single pulses of a ruby laser. Samples processed with the lowest energies show strong damage and incomplete electrical activation as deduced from Raman and PCIV measurements, respectively. Raman microprobe in depth analysis and PCIV profiles also suggest the presence of a damaged region with incomplete electrical activation at the boundary between the molten layer and the solid substrate.
TL;DR: An analysis of the spectroscopic characteristics of a chromium doped gadolinium gallium garnet crystal substituted by cations Ca2+, Mg2+, Zr4+ has been performed.
TL;DR: In this article, the phase speeds of the waves are vph = ±ω 0/kg, where kg is the wave number of the grating and ω 0 is the frequency of the CO2 laser.
Abstract: A plasma with a modulated density of n/n=8% was produced by illuminating a grating with a ruby laser at an intensity of 1010 W/cm2. A CO2 laser of intensity 3×1011 W/cm2 then irradiated this modulated plasma and generated plasma waves. The phase speeds of the waves are vph = ±ω0/kg, where kg is the wave number of the grating and ω0 is the frequency of the CO2 laser. Electrons were injected at an energy of 92 keV in one of the plasma waves. In order for the phase speed of the wave to synchronize with the accelerating electrons, a grating with constantly increasing line spacing (chirped) was used. Some electrons accelerated by 70 keV in 70 μm (gradient of 1 GeV/m) were detected, but the number of accelerated electrons was three orders of magnitude less than the expected value. This discrepency is the result of a large electric field perpendicular to the surface of the grating, which deflects the electrons onto the grating. This detrimental field is produced when fast electrons are emitted by the plasma, and leave it positively charged. Some techniques to remedy this difficulty are proposed.
TL;DR: In this paper, the results and analysis of experiments carried out on a dye Q-switch to evaluate its operational characteristics are presented, with regards to pump energy, dye absorbance, output energy and timing of pulse emergence.
Abstract: This paper presents the results and analysis of experiments carried out on a dye Q-switch to evaluate its operational characteristics. The work was performed on a ruby laser, Q-switched by cryptocyanine in methanol solution. Investigations of performance with regards to pump energy, dye absorbance, output energy and timing of pulse emergence are graphically presented. These results were used to derive the efficiency of Q-switching for varying dye absorbance. Finally, optimization of the Q-switch performance for different requirements of the laser is considered.
TL;DR: In this article, the multi-shot evolution of laser-induced periodic structure was studied by the time-resolved optical diffraction and reflection from the surface of polycrystalline silicon-on-insulator during the accumulation of 20 ns ruby laser pulses.
Abstract: The multi‐shot evolution of laser‐induced periodic structure was studied by the time‐resolved optical diffraction and reflection from the surface of polycrystalline silicon‐on‐insulator during the accumulation of 20 ns ruby laser pulses. In contrast to the results previously reported for the bulk sample, it was observed that the channel of the periodic structure development changed during the multiple irradiations even with a fixed fluence. The observed change occurs because the energy absorption is enhanced by the presence of the periodic structure preformed by the preceding pulses, and the absorbed laser energy at the polycrystalline layer is insulated by the underlying SiO2 layer. A previously unappreciated dip structure was observed in the time‐resolved diffraction and a possible explanation is suggested postulating the preferential energy deposition in the valleys of the periodic structure.
TL;DR: The LIDAR Thomson scattering method is a powerful new technique by which the electron tempera-ture and the density in magnetic confinement plasma devices can be measured through only one window, according to the principle of laser radar (LIDAR).
Abstract: LIDAR Thomson scattering method is a powerful new technique by which the electron tempera-ture and the density in magnetic confinement plasma devices can be measured through only one window, according to the principle of laser radar (LIDAR). After the successful measurement in the JET tokamak, the application of this technique to the ITER tokamak is under taken. Instead of the ruby laser system used in the first experiment at JET, a‘new laser’with an output energy of 2-10 J in 100-300ps FWHM at 10-100 Hz is required in a wavelength region of 700-800 nm, to improve temporal and spatial resolution. The present review introduces the history and the present situation of the LIDAR Thomson scattering method, and discusses the possibility of the development of the ‘new laser’.
03 Feb 1992
TL;DR: In this article, a high-resolution, multi-frame, image-converter camera using laser illumination has been developed by the Lawrence Livermore National Laboratory and is being used to observe the liner implosion and jet formation process in shaped charges.
Abstract: A high-resolution, multi-frame, image-converter camera using laser illumination has been developed by the Lawrence Livermore National Laboratory and is being used to observe the liner implosion and jet formation process in shaped charges. The combination of a short 15-ns exposure time and monochromatic laser illumination provides clear, sharp images of the linear collapse and jet formation process unobscured by luminous air shocks or motion blur. The camera as currently configured can take eight independent frames, or four pairs of stereo images. A ruby laser system provides the multiple-pulse illumination source. In stereo images of a copper-lined shaped charge, the liner deformation, including tiny imperfections, and the jet formation processes are clearly revealed. Grid lines placed on the surface of the liner remain intact and can be used for comparison with code calculations. 18 refs.
01 Jan 1992
TL;DR: A gamma-ray laser was proposed to stimulate the emission of radiation at wavelengths below 1 A from excited states of nuclei in this paper, however, the difficulties in realizing such a device were considered insurmountable when the first cycle of study ended in 1981.
Abstract: A gamma-ray laser would stimulate the emission of radiation at wavelengths below 1 A from excited states of nuclei However, the difficulties in realizing such a device were considered insurmountable when the first cycle of study ended in 1981 Nevertheless, research on the feasibility of a gamma-ray laser has taken a completely new character since then A nuclear analog of the ruby laser has been proposed and many of the component steps for pumping the nuclei have been demonstrated experimentally A quantitative model based upon the new data and concepts of this decade shows the gamma-ray laser to be feasible if some real isotope has its properties sufficiently close to the ideals modeled
TL;DR: In this article, a technique of pulsed Ruby laser induced liquid-solid interface reaction is employed to induce controlled and selective oxide growth on GaAs (111), and small-angle and bulk XRD spectra have been recorded at different stages of processing for investigations of the structural states near the surface and the interface regions.
TL;DR: In this paper, the wavelength dependence of the fragmentation of gallstones was investigated using pulsed excimer, ruby and Nd-YAG lasers, and the fluence threshold for plasma production and the associated acoustic signal was found to depend on the absorption coefficient at the laser wavelength.
Abstract: The wavelength dependence of the fragmentation of gallstones was investigated using pulsed excimer, ruby and Nd-YAG lasers. Fracturing is due to the shock waves produced by the plasma formed at the irradiated surface. The fluence threshold for plasma production and the associated acoustic signal was found to depend on the absorption coefficient at the laser wavelength. Using a simple model based on a thermal mechanism for plasma production the fluence threshold at different wavelengths can be predicted and the effect of the duration of the irradiating pulse can be qualitatively explained.
TL;DR: In-diffusion of Ti in LiNbO3 has been studied with many different lasers, obtaining promisingly good results in the case of a pulsed ruby laser as mentioned in this paper.
Patent•
24 Apr 1992
TL;DR: In this article, a silver salt-based photosensitive material for holograms is arranged at a prescribed position in using the holograms of the glass plate 6, and spread is provided through an argon laser device 1 to a beam splitter 2, mirrors 3, 3' and 3'' and object lenses 4 and 4'.
Abstract: PURPOSE:To enable obtaining of a diffraction pattern without any image strain by arranging a silver salt-based photosensitive material for holograms at a prescribed position of vehicular glass, irradiating the photosensitive material with pulsed ruby laser beams and exposing the material to the laser beams. CONSTITUTION:A vehicular glass plate 6 is placed on a supporting frame 8, tilted at 28-45 deg. and firmly fixed onto a vibration removing pedestal 10 and vacuum contact bonded through a flexible pressure-resistant pipe 8 for evacuation. A silver salt-based photosensitive material 7 for holograms is then arranged at a prescribed position in using the holograms of the glass plate 6, and spread is provided through an argon laser device 1 to a beam splitter 2, mirrors 3, 3' and 3'' and object lenses 4 and 4'. Interference fringes are formed on the photosensitive material 7 with pulsed laser beans 5 and 5' having the spread and recorded on the photosensitive material 7.