Showing papers on "Ruby laser published in 2009"

Meta-analysis of hair removal laser trials

Abstract: Traditional hair-removal techniques have included shaving, waxing, chemical depilation, and electrolysis. All of these methods result in temporary hair removal. The theory of selective photo thermolysis led to the development of a variety of different laser systems. These lasers range from the short end of spectrum, with the 694-nm ruby laser, to the middle, with the 755-nm alexandrite and 810-nm diode lasers, and to the long end with the 1,064-nm Nd:YAG laser. We made a systematic review on the clinical trials with use of various laser sources for hair removal, so all clinical trials related to hair removal lasers in 1998-2003 were considered after elimination of heterogenite sources in data store. Trial results were synthetized on the basis of kind of laser. Our study clarified that hair reduction at least 6 months after the last treatment and hair reductions were 57.5, 42.3, 54.7, and 52.8% after three sessions for diode, Nd:YAG, alexandrite and ruby, respectively. We compared the result with use of analysis of variance method (Scheffes) and double comparison with use of Student's t test. Our results clarified that diode laser is the most effective, and Nd:YAG has the least effect of hair removal.It seems that diode and alexandrite lasers are proper for hair removal, but as we need high fluence in the darker skin types and this is accompanied with higher complications, diode is advised for lighter skin, and we advised alexandrite laser for darker skin types.

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

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

Laser assisted cavity preparation and adhesion to erbium-lased tooth structure, part 1 : laser-assisted cavity preparation

Abstract: The use of the ruby laser (693.4 nm) was first described in 1960, and it was applied for hard tissue ablation in 1964. Different wavelengths [Nd:YAG (1.065 microm), CO2 (9.6 microm), Ho:YAG (2.12 microm)] were consequently explored. Due to massive thermal side effects, these wavelengths caused increased temperature in dental pulp, as well as microcracks and carbonization. The use of this laser for dental hard tissue preparation was eventually abandoned. At the end of the 1980s, excimer lasers (ultraviolet) and the erbium laser (infrared) were developed, with the advantages of improved temperature control and smaller penetration depths. With the development of smaller devices and improved knowledge of how to limit damage to the surrounding tissues, new ablation techniques were established in the 1990s. There is still contradiction in the current literature, however, in that different wavelengths are advocated for hard tissue removal, and heterogeneity in laser parameters and power densities remain. In this review, the effects of the wavelengths presently used for cavity preparation are evaluated. We conclude that erbium lasers (Er:YAG and Er,Cr:YSGG) are most efficient and, with the right parameters, the thermal side effects are small. There is a substantial need for "gold standards", although this is difficult to establish in practice owing to different laser parameters (including pulse repetition rate, amount of cooling, energy delivered per pulse, and types of pulses) and target specificity (tissue interaction with sound or decayed enamel or dentin, and the extent of (de)mineralization) which influence tissue interaction.

Laser in Dentistry-Review

Abstract: Laser is one of the most captivating technologies in dental practice since Theodore Maiman in 1960 invented the ruby laser. Even though, introduced as an alternative to the traditional halogen curing light, the laser now has become an instrument of choice, in many dental applications. This paper gives an insight on laser in dentistry.

Diode Laser Cyclophotocoagulation

Abstract: Cyclodestructive procedures are generally used for refractory glaucomas. Previously it has been carried out by various methods like surgical excision of ciliary body,1 cyclodiathermy,2,3 cycloirradiation,4 cycloelectrolysis,5 cyclocryotherapy,6-9 ultrasound,10 microwave cyclodestruction,11 and currently by cyclophotocoagulation. Laser cyclophotocoagulation has now become the principal method of cyclodestrive procedures. Various lasers has been used for this purpose which includes ruby, Nd:YAG, argon, krypton and diode laser, etc. Beckman and Sugar first popularized the use of trans-scleral cycpophotocoagulation (TSCPC) by ruby laser in early 1970s.12,13 Later they discovered that Nd:YAG laser was more effective in penetrating sclera and energy absorbed by ciliary body is also optimum.13 Secondary glaucomas like postpenetrating keratoplasty glaucomas, aphakic/pseudophakic glaucomas, neovascular glaucomas and glaucoma following trauma are examples where cyclodestructive procedures are favored due to a poor response to standard filtering procedures.14-16

Comparison of a single treatment with Q-switched ruby laser and Q-switched Nd:YAG laser in removing black-blue Chinese tattoos.

Abstract: Background: Black and blue are two popular colors in Chinese tattooing. Two Q-switched lasers, ruby and Nd:YAG, are effective for tattoo removal. No reference with regard to a comparison of the effects and adverse reactions in Chinese individuals has been made in the literature. Objective: To compare a single treatment of black-blue tattoos with the Q-switched ruby laser and Q-switched Nd:YAG (1064 nm) laser. Methods: A total of 35 Chinese patients with black-blue tattoos at the laser center of the Institute of Dermatology, Chinese Academy of Medical Sciences were enrolled into a self-control study. Tattoos were split into two parts or two nearby tattoos on the same body part were used; one side was treated with the Q-switched ruby laser and the other with the Q-switched Nd:YAG laser. Immediate response, treatment outcome and adverse effects were compared. The statistical significance level was set at p< 0.05. Results: Edema and exudation were more common immediately after ruby laser treatment (p<...

Phase transitions in erbium-doped silicon exposed to laser radiation

Abstract: The dynamics of phase transitions induced by nanopulsed ruby laser radiation (80 nsec, 2 J/cm 2 ) both in silicon layers doped with erbium ions and in those containing doped erbium and oxygen have been studied by an optical probing method. It is shown that the reflectivity behavior of structures under pulsed irradiation is governed by phase transitions (melting and crystallization) of implanted silicon and also by interference effects at the interfaces of the resulting phases. It is established that the profiles of erbium distribution change under nanosecond laser irradiation and that the dopant is forced out to the surface due to a segregation effect at small implantation doses. As the implanatation dose increases, diffusion deep into the sample tends to prevail over segregation. A considerable increase in the photoluminescence peak intensity at 0.81 eV is found after both the pulsed laser processing and thermal post-annealing of doped samples as opposed to spectra of samples subjected either to thermal annealing or to pulsed laser irradiation.

The effect of pulsed ruby laser on retinal pigment epithelium in vitro

Abstract: Since the introduction of the laser in 1960, many attempts have been made to ascertain threshold values for damage to the sensitive retinas of various mammalian eyes employing in vivo methods. In v i t r o studies have been made by Rounds (1965) and Rounds et al. (1965) on cells and tissues in culture and by King & Geeraets (1968) on the effects of Q-switched ruby laser radiation upon explants of ten-day old chick embryo retinal pigment epithelium. The investigation presented here has been patterned after the latter study, substituting a pulsed ruby laser, thereby affording a pulse duration in the microsecond instead of the nanosecond range. Previous investigations (Geeraets et al. 1965, Ham et al. 1958, 1965, 1966) have demonstrated the dependence of retinal threshold damage by thermal energy density (irradiance) upon both duration of the exposure and the spot size of the retinal image. The power density required to produce a threshold lesion has been shown to be inversely proportional to the diameter of the spot size for relatively long exposure times (> 100 ms) as a result of the greater heat dissipation associated with the smaller lesion geometry. The threshold energy density

Lasers in Dentistry: Review

Abstract: Laser is one of the most captivating technologies in dental practice since Theodore Maiman in 1960 invented the ruby laser. Even though, introduced as an alternative to the traditional halogen curing light, the laser now has become the instrument of choice, in many dental applications. This paper gives an insight on laser in dentistry.

Azimuthal dependence of the two-photon absorption coefficient for CdP2 crystals with tetragonal syngony

Abstract: We studied the two-photon absorption coefficient (β) for cadmium diphosphide (CdP2) single crystals in the tetragonal modification vs. the polarization azimuth (φ) of the incident light for intensities close to the optical breakdown (or optical damage) threshold for the crystal (11 MW/cm2). We have established that the value of βmax = 0.16 cm/MW is reached for φ = 0, i.e., for the ordinary wave. At the lasing frequency of a ruby laser, β⊥/β|| = 2.13, which suggests anisotropy of the two-photon absorption in the studied crystals. These dependences are needed for design and fabrication of quantum electronics and nonlinear optics elements whose operation is based on the use of the two-photon absorption effect for high radiation fluxes.

Intracavity shg of a ruby laser pumped by an intracavity frequency doubled coupled cavity diode pumped nd-laser

Abstract: A system and method for generating ultraviolet laser radiation by pumping a ruby based active laser medium (21", 93) with an output from a laser cavity (34', 71) which output is the frequency doubled (30') fundamental of a diode pumped solid state laser material (21', 75). The laser emission of the ruby based active laser material is in turn frequency double by a non linear crystal (30") placed inside the laser cavity. For efficient frequency conversion the laser cavities preferably use resonant reflectors. Enhancement of intracavity second-harmonic generation by using a coupled cavity with optimized reflectivity of the SH output coupler (48', 48") which acts as a beam splitter.