Showing papers on "Ruby laser published in 1998"
TL;DR: Permanent, nonscarring alopecia can be induced by a single treatment with high-fluence ruby laser pulses, and miniaturization of the terminal hair follicles seems to account for this response.
Abstract: Objective To assess the permanence of hair removal by normal-mode ruby laser treatment. Methods Hair removal was measured for 2 years after a single treatment with normal-mode ruby laser pulses (694 nm, 270 microseconds, 6-mm beam diameter). Observations Six test areas on the thighs or backs of 13 volunteers were exposed to normal-mode ruby laser pulses at fluences of 30 to 60 J/cm 2 delivered to both shaved and wax-epilated skin. In addition, there was a shaved and wax-epilated control site. Terminal hairs were manually counted before and after laser exposure. Transient alopecia occurred in all 13 participants after laser exposure, consistent with induction of telogen. Two years after laser exposure, 4 participants still had obvious, significant hair loss at all laser-treated sites compared with the unexposed shaved and wax-epilated control sites. In all 4 participants, there was no significant change in hair counts 6 months, 1 year, and 2 years after laser exposure. Laser-induced alopecia correlated histologically with miniaturized, velluslike hair follicles. No scarring and no permanent pigmentary changes were observed. Conclusions Permanent, nonscarring alopecia can be induced by a single treatment with high-fluence ruby laser pulses. Miniaturization of the terminal hair follicles seems to account for this response.
242 citations
TL;DR: Investigation of how the various stages of the hair follicle growth cycle influence follicle destruction by ruby laser treatment using a model of predictable synchronous hair growth cycles in the infantile and adolescent mice suggests treatment strategies for optimal laser hair removal.
96 citations
TL;DR: A systematic review of the hair removal laser systems currently available is attempted and it is expected that permanent hair removal may eventually be possible.
Abstract: BACKGROUND. The recent development of numerous laser-assisted hair removal techniques has produced confusion in the field of cutaneous laser surgery. OBJECTIVES. A systematic review of the hair removal laser systems currently available is attempted. Appropriate patient selection, treatment protocols, and discussion of each system's advantages, disadvantages, and complications is provided. CONCLUSIONS. Techniques involving the use of selective Q-switched Nd:YAG and long-pulsed alexandrite and ruby laser systems provide a significant delay in hair growth. With further technologic advances and understanding of proper treatment parameters and intervals, it is expected that permanent hair removal may eventually be possible. © 1998 by the American Society for Dermatologic Surgery, Inc. Dermatol Surg 1998;24: 1399-1405.
95 citations
TL;DR: Overall, regardless of skin type or targeted body region, patients who underwent three treatment sessions demonstrated an average 35% regrowth in terminal hair count compared with baseline pretreatment values 6 months after initial therapy.
Abstract: background. Laser hair removal is rapidly becoming a widely used modality. Clinical studies are needed to assess these hair removal systems. The long-pulsed ruby laser is one such modality for the removal of unwanted hair.
objectives. To evaluate the efficacy of the long-pulsed ruby laser (694 nm, 3-msec pulsewidth, 7- or 10-mm spot size) in removing unwanted hair, and to provide treatment guidelines for the proper utilization of this laser system.
methods. Forty-eight areas of unwanted facial and body hair from 25 patients with blonde, brown, or black hair were treated with the long-pulsed ruby laser at fluences between 10 and 40 J/cm2. Hair regrowth was measured at 4 weeks after the first treatment, 4 weeks after the second treatment, 4 weeks after the third treatment, and 16 weeks after the third treatment by counting the number of terminal hairs compared with baseline pre-treatment values. All complications and treatment outcomes were documented.
results. The mean percent of regrowth after the first treatment was 65.5%, 41% after the second treatment, and 34% after the third treatment. Overall, regardless of skin type or targeted body region, patients who underwent three treatment sessions demonstrated an average 35% regrowth in terminal hair count compared with baseline pretreatment values 6 months after initial therapy.
conclusion. Long-pulsed ruby laser treatment resulted in significant hair growth delay in most cases. Repeated laser treatments produced an increased number of vellus hairs, an increase in growth delay, and a decreased percentage of hair regrowth.
68 citations
TL;DR: Two patients in whom the Q-switched ruby laser failed to successfully treat clinically atypical-appearing solar lentigines are described, highlighting the importance of careful clinical assessment before any laser surgery and the need to advise patients to return for evaluation should pigmentation return.
Abstract: Cutaneous lasers, including argon, Q-switched Nd:YAG, Q-switched ruby, Q-switched alexandrite, and short pulsed dye lasers, have been used to treat solar lentigines and other benign melanocytic lesions. However, the effects of these lasers at standard fluences on atypical melanocytic lesions have not been examined. We describe two patients in whom the Q-switched ruby laser failed to successfully treat clinically atypical-appearing solar lentigines. In both, clinically atypical-appearing melanocytic lesions were treated with excellent initial cosmetic results. In the first patient, the pigmentation returned several months after treatment and continued to increase in size and color. A biopsy specimen 30 months after Q-switched ruby laser therapy revealed a lentigo maligna melanoma. In the second patient, the lesion recurred 6 months after Q-switched ruby laser therapy, and a biopsy specimen 1 year after treatment showed an early lentigo maligna. Thus Q-switched ruby lasers and other cutaneous lasers capable of targeting melanin may be inadequate to eliminate lentigo maligna and other atypical melanocytic lesions completely. These cases emphasize the importance of careful clinical assessment before any laser surgery and the need to advise patients to return for evaluation should pigmentation return.
61 citations
TL;DR: In this paper, two ruby laser systems employing multiple Q-switching technology are developed to provide ruby laser light for high-speed photography, which can produce more than 50 pulses at repetition rates up to 500 kHz with nearly constant pulse-to-pulse energies.
Abstract: Two ruby laser systems employing multiple Q-switching technology are developed to provide ruby laser light for high-speed photography. Potential applications include ballistics and flow visualization as well as nondestructive test evaluation using laser imaging diagnostics such as photography, holography, and various interferometric techniques. The laser systems produce more than 50 pulses at repetition rates up to 500 kHz with nearly constant pulse-to-pulse energies. One system, based on a commercial laser, provides multiple pulses of holographic quality light with individual pulse energies of the order of 10 mJ, pulse widths of 50 ns, and a pulse train length of more than 300 μs. A new ruby laser system is developed to provide higher pulse energies, of the order of 350 mJ per pulse, with 10 ns pulse widths and 140 μs pulse train length. The method for multiple Q-switching by modulating the Pockels cell’s quarter-wave voltage and the formation of an individual Q-switched pulse is investigated. The energy within the individual pulses formed in the oscillator cavity is successfully increased by propagating through an amplification section, without degradation of the temporal or pulse-to-pulse amplitude stability. E´talons for longitudinal mode selection and an iris for spatial mode selection are incorporated into the lower energy system and an image of a reconstructed hologram is presented. Camera capabilities and the implications of higher pulse energies are also investigated. © 1998 Society of Photo-Optical Instrumentation Engineers.
41 citations
TL;DR: The long-pulsed ruby laser uses light at a wavelength of 694 nm with a 3-msec pulse to destroy hair to remove hair.
Abstract: There are a variety of traditional treatments for the removal of unwanted hair. Recently, lasers have been developed to remove hair. The long-pulsed ruby laser uses light at a wavelength of 694 nm with a 3-msec pulse to destroy hair. Seventy-two patients were treated with this laser from one to four times in a variety of areas. Seventy-one patients had an alteration in their hair growth. One patient had no change in her hair pattern. There were no scars and no permanent changes in pigmentation. Laser hair removal is a useful method for the treatment of unwanted facial and body hair.
37 citations
TL;DR: In this article, an influence of laser-induced stress and shock waves on photoelectric properties of epitaxial n- (CMT) films with a cellular structure was studied, and it was established that the strongest photosensitization of CMT took place in deep-seated layers where the shock wave was formed.
Abstract: An influence of laser-induced stress and shock waves on photoelectric properties of epitaxial n- (CMT) films with a cellular structure was studied. Irradiation of CMT films with nanosecond ruby laser pulses resulted in a modification of photoconductivity spectra and an increase in the photosensitivity because of segregation of electrically active point defects at the cell boundaries (acting as sinks) and also because of changes in their electron states as a result of action of the laser-generated stress and shock waves. Using the calculations of the temperature of the samples, the depth of shock wave formation and the amplitude of shock wave at laser irradiation, it was established that the strongest photosensitization of CMT took place in deep-seated layers where the shock wave was formed. This deduction was confirmed by an increase in the photosensitivity of purpose-designed samples coated with copper foil in such a way as to exclude the photo- and thermal effects under laser irradiation of CMT solid solutions.
20 citations
01 Jan 1998
TL;DR: In this article, a ruby laser patient still had hypopigmentation 90 days after treatment, but only 10% evaporated instantaneously, while in Q-switched mode the ruby laser was experienced by approximately 10%, but only one evaporate instantaneously.
Abstract: ation was experienced by approximately 10%, but only one evaporate instantaneously. In Q-switched mode the ruby laser patient still had hypopigmentation 90 days after treatment. emits very short pulses in the nano-second range and hence Due to variability of hair density as well as anagen and endogenous and artificial pigment granules in the skin will be telogen phase durations in different anatomical locations, firm damaged selectively. This phenomenon has been utilized for conclusions regarding the long-term effect still cannot be drawn. tattoo removal (4, 5) and for treatment of benign pigmented
17 citations
TL;DR: In this article, the authors showed that the kinetic energy of the atoms ejected from the laser irradiated target plays a crucial role in the observed lowering of crystallisation temperature, by means of ablation rate measurements.
Abstract: Silicon carbide films were deposited on top of silicon substrates maintained at various temperatures using the technique of Pulsed Laser Deposition (PLD) employing an excimer or a ruby laser. We found the deposited films to be crystalline for substrate temperature of only 500 °C for XeCl deposition and 700 °C for ruby. Films deposited at room temperature are amorphous and, as in the case of amorphous films obtained by high fluence ion implantation, require an annealing at a temperature as high as 1000 °C to crystallise. We demonstrated, by means of ablation rate measurements, that the kinetic energy of the atoms ejected from the laser irradiated target plays a crucial role in the observed lowering of crystallisation temperature.
10 citations
TL;DR: In this article, the polarized differential absorption spectra of the Cr4+ ion in Cr4:SrGd4(SiO4)3O and Cr4 +:CaGd 4 (SiO 4 )3O crystals were studied under picosecond excitation.
Abstract: The polarized differential absorption spectra of the Cr4+ ion in Cr4+:SrGd4(SiO4)3O and Cr4+:CaGd4(SiO4)3O crystals were studied under picosecond excitation. Polarized excited-state absorption (ESA) spectra were derived from the differential absorption spectra by use of the ground-state absorption (GSA) and ESA cross sections obtained from intensity-dependent transmission measurements. ESA was assigned to the 3T2→3T1(3F) and 3T2→3T1(3P) transitions of the Cr4+ ion. Passive Q switching of a Nd3+:YAlO3 (1.08-μm) and a ruby (694-nm) laser with the Cr4+:SrGd4(SiO4)3O and the Cr4+:CaGd4(SiO4)3O crystals as saturable absorbers was demonstrated. The pulse duration (energy) of the Q-switched Nd3+:YAlO3 and the ruby laser were found to be 55 ns (2.4 mJ) and 90 ns (20 mJ), respectively.
TL;DR: In this article, a multi-pulsed ruby laser system has been developed utilizing repetitive Q-switching technology, which is capable of producing more than 50 pulses at a repetition rate in excess of 500 kHz with a nearly constant pulse-to-pulse energy of several mJ.
Abstract: A multi-pulsed ruby laser system has been developed utilizing repetitive Q-switching technology. The laser system has applications in fields where high speed dynamic events are studied, e.g., ballistics and non-destructive test evaluation, using laser imaging diagnostics such as photography, holography, and various interferometric techniques. The laser system is capable of producing more than 50 pulses at a repetition rate in excess of 500 kHz with a nearly constant pulse-to-pulse energy of several mJ. The individual laser pulses are approximately 50 ns FWHM and the envelope of multiple pulses is greater than 200 microseconds. The method for multiple Q-switching by modulating the Pockels cell's quarter wave voltage and the formation of an individual Q- switched pulse have been investigated and a computational model has been formulated. The energy within the individual pulses formed in the oscillator cavity has been successfully increased without degradation of the temporal or pulse-to- pulse amplitude stability by propagating through an amplification section. Data of an amplified pulse train at a repetition rate of 500 kHz is given. Etalons for longitudinal mode selection and an iris for spatial mode selection have been incorporated for increased coherence and an image of a reconstructed hologram is presented.
01 Jan 1998
TL;DR: In this paper, a multi-pulsed ruby laser system has been developed utilizing repetitive Q-switching technology, which is capable of producing more than 50 pulses at a repetition rate in excess of 500 kHz with a nearly constant pulse-to-pulse energy of several mJ.
Abstract: A multi-pulsed ruby laser system has been developed utilizing repetitive Q-switching technology. The laser system has applications in fields where high speed dynamic events are studied, e.g., ballistics and non-destructive test evaluation, using laser imaging diagnostics such as photography, holography, and various interferometric techniques. The laser system is capable of producing more than 50 pulses at a repetition rate in excess of 500 kHz with a nearly constant pulse-to-pulse energy of several mJ. The individual laser pulses are approximately 50 ns FWHM and the envelope of multiple pulses is greater than 200 μs. The method for multiple Q-switching by modulating the Pockels cell's quarter wave voltage and the formation of an individual Q-switched pulse have been investigated and a computational model has been formulated. The energy within the individual pulses formed in the oscillator cavity has been successfully increased without degradation of the temporal or pulse-to-pulse amplitude stability by propagating through an amplification section. Data of an amplified pulse train at a repetition rate of 500 kHz is given. Etalons for longitudinal mode selection and an iris for spatial mode selection have been incorporated for increased coherence and an image of a reconstructed hologram is presented.
TL;DR: In this article, the authors studied the structure defects arising in the HgTe, (Cd,Hg)Te and CdTe crystals under both ruby laser pulse irradiation of ms duration and change carriers concentrations profiles of the near-surface layers disturbed by laser were conducted.
TL;DR: In this article, wave front conjugation in four-wave interaction (FWI) of monopulse radiation of ruby laser in dye-doped liquid crystals (DDLC) was obtained.
Abstract: Wave-front conjugation (WFC) in four-wave interaction (FWI) of monopulse radiation of ruby laser in dye-doped liquid crystals (DDLC) was obtained. The amplification of conjugation wave was observed. The amplitude gratings and the phase gratings on thermal nonlinearity give the contribution in wave front conjugation.
TL;DR: In this paper, the photoconductivity, photomagnetic effect, magnetic field dependences of the Hall coefficient and of the relative conductivity in n and p-type Cd x Hg 1− x Te (CMT) solid solutions, which were irradiated with nanosecond ruby laser pulses, were distinguished by both the structural and the component composition.
TL;DR: In this article, surface hardening of oil-hardened nonshrinking (OHNS) steel using Ruby laser in normal mode was studied and it was found that surface hardness increases thrice the size of base material and the microstructure of the laser-heated zone changes from pearlite phase to martensite phase.
Abstract: Surface modification of metals and alloys using lasers has acquired considerable importance because the changes achieved are highly localized and superficial. In this process the mechanical and structural properties of the bulk are retained as such because of the high temperature gradient and high rate of change of temperature that are unattainable by conventional methods. The present report is on surface hardening of oil-hardened nonshrinking (OHNS) steel using Ruby laser in normal mode. It is found that surface hardening increases thrice the size of base material and the microstructure of the laser-heated zone changes from pearlite phase to martensite phase.
01 Jun 1998
TL;DR: In this article, a rectangular metal plate is randomly excited by a shaker or by the impact of a small rod, and an optical measuring system for the evaluation of transient deformations is used.
Abstract: A rectangular metal plate is randomly excited by a shaker or by the impact of a small rod. To investigate the temporal development of the induced deformation, an optical measuring system for the evaluation of transient deformations is used. A ruby laser, which is able to produce four laser pulses within a few laser pulses within a few microseconds and a setup of three CCD-cameras for recording the four pulses/interferograms were used. The images of the recorded holographic interference patterns are captured digitally with a framegrabber inside a PC. The reconstruction of the holograms is performed also digitally in the computer. For the later is obtained from the complex amplitude and the deformation between two laser pulses is calculated from phase subtraction and phase unwrapping of these two holograms. Each deformation image can be decomposed into the eigenmodes of the plate, which have to be known/measured before. By measurement of four holograms with a known pulses separation one is able to determine the deformation states between each adjacent pulse and at least the temporal development of the deformation and contributing magnitude coefficients of the eigenmodes.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this article, the surface potential development in chalcogenide vitreous semiconductors is determined by studying the corona discharge in response to exposure to radiation from a Q-switched nanosecond-pulse ruby laser.
Abstract: The quantum efficiency value is determined by studying the surface potential development in chalcogenide vitreous semiconductors. Sensitization by a corona discharge in response to exposure to radiation from a Q-switched nanosecond-pulse ruby laser is achieved. A method to calculate the quantum efficiency is presented, and its dependence on parameters such as the exposure moment switch, temperature, charging electrode potential, and radiation energy density is studied. The mobility of the holes is determined by the time of flight of carrier packets. The observed effects are explained using the residual conduction mechanism. © 1998 Society of Photo-Optical Instrumentation Engineers.
Patent•
04 Feb 1998
TL;DR: In this paper, human or animal hair is removed from a body using a laser beam which is reflected by a mirror with an articulated mount, onto a scanner unit and thence onto the skin.
Abstract: Human or animal hair is removed from a body using a laser beam which is reflected by a mirror with an articulated mount, onto a scanner unit and thence onto the skin. The mirror converts the light beam into a parallel beam with an adjustable cross-section. The laser is a 694 nm ruby laser with an output energy of up to 40 J/cm2. The beam is typically 5 x 5 mm to 10 x 10 cm.
TL;DR: The most probable mechanism involved in this compensation is nonlinear backscatter in the resonator as discussed by the authors, which compensates for resonator scattering as a result of self-regulation.
Abstract: From the condition of generation (of the reproducibility of opposite waves for a pass around a resonator) it follows that in addition to amplitude-phase changes an active medium must also compensate for backscatter in the resonator. The most probable mechanism involved in this compensation is nonlinear backscatter. In the process of generation, nonlinear scattering compensates for resonator scattering as a result of self-regulation. Amplitude-frequency characteristics are determined by the types of vibrations of a resonator, whereas nonlinear effects specify these characteristics.
23 Sep 1998
TL;DR: In this article, the result of experimental studies of thermal mechanism of optical response of a c.w. He-Ne laser probe beam when a dye-activated nematic layer is irradiated with free-lasing radiation of a ruby laser are analyzed.
Abstract: The result of experimental studies of thermal mechanism of optical response of a c.w. He-Ne laser probe beam when a dye-activated nematic layer is irradiated with free-lasing radiation of a ruby laser are analyzed. Experimental geometry is such that planar-oriented nematic laser is perpendicular to the direction of the acting ruby laser beam, the electric field vector of this radiation forming an angle of 45 degrees with the layer director. Analysis of experimental oscillograms shows that, besides thermal impact whose intensity is determined by the number of oscillations, there is also variation in the oscillating signal amplitude. Their amplitude is determined by an azimuthal angle between vector E of acting laser beam and layer director. This angle can be induced only with action of electrical field of radiation.
TL;DR: A study from the Wellman Laboratories of Photomedicine in Boston, which concluded that ruby laser hair removal is effective, and a recent British study provided data in support of these claims.
Abstract: Last year we reviewed a study from the Wellman Laboratories of Photomedicine in Boston, which concluded that ruby laser hair removal is effective (see JWDerm, Mar 1997, p. 21). A recent British study provided data in support of these claims (see JWDerm, Aug 1998, p. 70). In the Boston study, 13 volunteer subjects each received a single treatment with a 270 μsec ruby laser at fluences of 30 to 60 J/cm …
TL;DR: In this article, the coherent radition-semiconductor interaction model based upon the time-dependent perturbation technique has been employed for the analytical study of transient pulse propagation and pulse break-up in direct-gap semiconductors.
TL;DR: In this article, an outdoor experiment is presented where a ruby oscillator and an amplifier are used as source, a laser beam travels from the source to a reflector, which simulates a target, reflected laser beam is focused into a SBS cell by a lens, and finally the phase conjugate light produced by the stimulated Brillouin scattering (SBS) effect return to the target.
Abstract: In laser propagation in the atmosphere, the wavefront of laser beam will be distorted by the atmospheric turbulence. The wavefront aberration can be compensated with the stimulated Brillouin-scattering (SBS) effect. In this paper, an outdoor experiment is presented. In the experiment, a ruby oscillator and an amplifier are used as source; a laser beam travels from the source to a reflector; which simulates a target; the reflected laser beam travels through the atmosphere and is focused into a SBS cell by a lens; finally the phase conjugate light produced by the stimulated Brillouin scattering (SBS) effect return to the target. The distance between the target and the SBS cell is 70 m. The Output energy of the ruby laser is 2 J. The laser beam spot and the phase conjugate light spot are recorded by a camera at the target. The result of the experiment shows that: the wavefront aberration is compensated in the process of laser beam and the phase conjugate light travels between the target and the SBS cell.