Showing papers on "Ruby laser published in 2003"

Incidence of side effects after laser hair removal

Abstract: Background Despite the widespread use of lasers for hair removal there are few data published on the incidence of side effects from this treatment. Objective The aim of this study was to generate data on a large number of patients receiving laser hair removal to obtain an accurate assessment of the incidence and type of side effects resulting from treatment. Methods A multicenter prospective study of patients presenting for laser hair removal was conducted to determine incidence of side effects in relation to skin type and laser or lasers used. Results Laser hair removal is associated with a low incidence of side effects that are self-limiting in the majority of cases. The highest incidence of side effects was seen in patients with darker skin treated with the long-pulsed ruby laser. Conclusions Laser hair removal is inherently safe. For darker Fitzpatrick skin types the long-pulsed neodymium:yttrium-aluminum-garnet laser is preferred to the ruby laser.

Laser Microtools in Cell Biology and Molecular Medicine

Abstract: Lasers for micromanipulation in cellular or subcellular dimensions have gained remarkable interest within the entire community of life science research and applications. In 1962, Bessis, for the first time, focused a ruby laser into a microscope to perform micromanipulation of cells under microscopic observation (1). Today, there exist two principles of laser micromanipulation that depend on the nature of the applied laser source. So- called "optical traps" are generated by coupling a continuous wave near an infrared laser into a routine micro- scope. Optical forces are generated within the small laser focal spot that attract microscopic small specimens and hold them there solely by radiation pressure forces. On the other hand, a focused, near diffraction limited pulsed UVA laser allows ablation and microdissection of biological material with high spatial resolution. There, focal diameters of less than 500 nm can be achieved depending on the numerical aperture of the applied objec- tive. These laser-based systems are the state of the art technologies for precise and noncontact micromanipula- tions with nanometer accuracy and have become indispensable tools in modern medicine and biotechnology, as will be outlined in this review article.

Laser Resistant Coatings

Abstract: Interest in laser resistant coatings started with Maiman’s invention of the ruby laser (Maiman 1960). It soon became apparent that the existing quality of optical coatings was insufficient to withstand the high-photon flux of a laser source (Glass and Guenther 1973). In 1965 the Office of Naval Research contracted with Baush & Lomb to study the damage thresholds of dielectric films and multilayer coatings to overcome the problems of absorption and coating defects (Turner 1972). In 1969, a symposium on Laser-Induced Damage in Optical Materials was formed and two years later, thin films became one of the four primary research topics. This symposium has been the premier repository of documented research in laser resistant optical thin films. Although the subject of laser damage in optical materials is a rather narrow field of research, there are some excellent books on the subject (Kozlowski 1995; Wood 1986).

Laser therapy of giant congenital melanocytic nevi

Abstract: Giant congenital melanocytic nevi (GCMN) are rare disfiguring potentially malignant lesions present at birth. The approach of these patients is based on two main considerations: attempt to minimize the risk of malignancy, and obtain an acceptable cosmetic result. Sometimes they are too large to be removed by multiple surgical excision or by use of osmotic expander. The objective of treatment of giant congenital nevi is to obtain ablation without side effects or after-effects from aesthetics. But for the moment such treatment doesn't exist. The aim of this review was to access treatment of GCMN with lasers as an alternative to surgery. Lasers should only be regarded as a treatment option for GCMN that cannot be surgically excised. For the moment laser therapy of GCMN should be restricted to well controlled studies or to individual patients in whom surgical procedures are not possible or would result in unacceptable scarring. Today ultrashort high energy pulsed CO2 laser and the normal mode ruby laser are the two lasers available. But the results are too unforeseeable, and painful with these two lasers. The combined use of normal mode and Q-switched ruby lasers or ultrashort high energy pulsed CO2 laser and Q-switched ruby or Nd:YAG lasers can give us a solution. In the future perhaps new Q-switched laser could give us a better way of treatment, with less pain, and no scars. We need an improvement of the technology in this field and hopefully the picosecond systems will be available in the future.

Lumbosacral hypertrichosis treated with the normal-mode ruby laser.

Abstract: Sir, Lumbosacral hypertrichosis is an uncommon occurrence that constitutes a significant cosmetic problem. Treatment with electrolysis is difficult and surgical excision seems to be the only permanent option. Surgery carries the risk of significant scarring and electrolysis is often impractical where a large area is affected. Recently, long-term hair removal using normal-mode ruby laser has been convincingly demonstrated at facial sites (1), and has been recommended for other body sites (2). Laser treatment removes unwanted hair through the selective photothermolysis of melanin-rich structures and results in light energy absorption in hair follicles, causing destruction (3). There is minimal absorption by surrounding tissues and thus skin damage is avoided. The technique seems to be more effective for darker hair and fairer skin types. Lasers most frequently used in hair removal include ruby, diode, Nd:YAG and Alexandrite. We performed a prospective study of patients specifically with lumbosacral hypertrichosis referred to our Laser Department for laser hair removal.

High-resolution ruby laser Thomson scattering diagnostic for the W7-AS stellarator

Abstract: After reconstruction, the ruby Thomson scattering diagnostic for the W7-AS stellarator is now in operation to again cover the complete plasma cross section (420 mm), where the former photomultiplier-based polychromator system has been replaced by two individual Littrow-type polychromator setups (focal length 50 cm), using intensified charge coupled device cameras for light detection. A single-pulse ruby laser with high pulse energy is used as a light source. The light scattered by the plasma electrons is imaged upon a set of 45 fiber bundles. 30 bundles provide a high spatial resolution of 4 mm at the inner edge of the plasma. The remaining part of the view chord is observed with a spatial resolution of 20 mm. At the output, the fiber bundles form the entrance slits of the Littrow-type spectrometers. The spectral resolution of the edge spectrometer can be modified by exchanging the diffraction grating. Depending on the installed diffraction grating (600 or 1800 lines/mm) a total wavelength range of 80 nm (suitable for plasma edge investigations) or 320 nm (suitable for gradient investigations) can be surveyed. The spectral intensity and geometrical calibration of the presented diagnostic setup can be done in situ by means of a neon spectral lamp and a calibrated tungsten strip lamp. The absolute sensitivity calibration for the system is achieved using either Raman (at 723.8 nm) or Rayleigh (at laser wavelength) scattering as hydrogen gas filled up in the vacuum vessel (up to 100 mbar). Examples of electron density and temperature profiles measured under different plasma conditions are presented.

Thomson scattering system for the diagnosis of the ETE spherical tokamak plasma

Abstract: A 10 J ruby laser Thomson scattering system was implemented on the ETE spherical tokamak to measure the density ne and temperature Te profiles. The laser probes the plasma at the horizontal midplane of the torus and the collection optics allows the observation of up to 22 points inside the plasma in the same plane. Radial profiles of plasma density and electron temperature were obtained for different times during the discharge by shot-to-shot procedure. Temperatures of up to 160 eV and densities of 2.2×1019 m−3 were measured. Since the level of stray light was too high, the calibration of the Thomson scattering system for density measurements was made using the nitrogen Raman technique instead of the usually applied Rayleigh method.

Pulsed-laser modification of germanium nanoclusters in silicon

Abstract: The effect of pulsed ruby laser radiation on Ge nanoclusters grown on a (100)-oriented Si substrate is studied. The energy density of radiation corresponds to the melting threshold of the Si surface. Changes in the structure of nanoclusters are analyzed by comparing the experimental Raman spectra to those calculated in terms of Born-von Karman and Vol’kenstein models. It is established that the action of one pulse changes the cluster size and partly relieves the compression. Still greater changes take place in a sample subjected to ten pulses. The Ge nanoclusters transform into clusters of GexSi1−x solid solution, presumably due to the stress-and vacancy-aided diffusion. Laser-induced thermal processes in germanium nanoclusters in silicon are numerically simulated.

Measurement of shock waves using phase shifting pulsed holographic interferometer

Abstract: A phase shifting pulsed holographic interferometer was applied to the experimental study of the propagation of laser-induced shock waves over metal plates. A double-pulsed ruby laser was used to generate the shock waves and to make a holographic interferogram of the wave fields. The phase shifting method with a dual-reference beam solved the sign ambiguity problem in holographic fringe patterns and allowed a quantitative evaluation of the phase of the interference patterns. The transient surface profile and propagation behavior of the shock wave over plates were investigated from the holographic fringe patterns.

Survey of Beamed Energy Propulsion Concepts by the MSFC Space Environmental Effects Team

Abstract: This will be a survey paper of work that was performed by the Space Environmental Effects Team at NASA's Marshall Space Flight Center in the area of laser energy propulsion concepts Two types of laser energy propulsion techniques were investigated The first was ablative propulsion, which used a pulsed ruby laser impacting on single layer coatings and films The purpose of this investigation was to determine the laser power density that produced an optimum coupling coefficient for each type of material tested A commercial off-the-shelf multi-layer film was also investigated for possible applications in ablative micro-thrusters, and its optimum coupling coefficient was determined The second type of study measured the purely photonic force provided by a 300W CW YAG laser In initial studies, the photon force resulting from the momentum of incident photons was measured directly using a vacuum compatible microbalance and these results were compared to theory Follow-on work used the same CW laser to excite a stable optical cavity for the purpose of amplifying the available force from incident photons

Emulsions for pulsed holography: new and improved processing schemes

Abstract: Recent improvements in the processing of commercially available holographic recording materials for pulsed holography are reviewed. Harmonics of pulsed Nd:YLF/Nd:Phosphate Glass, Nd:YLF, Nd:YAG laser's, and the fundamental wavelength of a pulsed Ruby laser were used as radiation sources for the recording of transmission and reflection holography gratings. It is shown that ultra-fine grain size materials such as PFG-03C and Ultimate-15 can be successfully applied for small and medium format pulsed holography applications. These small grain size emulsions are especially important in the areas of artistic archival portraiture and contact Denisyuk micro-holography of living objects, where noiseless image reconstruction is of a primary concern. It suggests that HOE's, such as full-color image projection screens, may be successfully recorded on PFG-03C holographic emulsions using a pulsed RGB laser. A range of commercial RGB pulsed lasers suitable for these applications are introduced. Visible wavelengths currently produced from these lasers covers the spectrum of 440 - 660nm. Latest developments of a full range of pulsed holographic camera systems manufactured by GEOLA that are suitable for medium and large format portraiture, medical imaging, museum artifact archival recording, and other types of holography are also reviewed with particular reference to new integrated digital mastering features. Finally, the initial commercial production of a new photopolymer film with a sensitivity range of 625-680nm is introduced. Initial CW exposure energies at 633nm were 30 - 50mJ/cm 2 ; with diffraction efficiencies of 75 - 80% observed with this new material.

Influence of pulsed laser radiation on the morphology and photoelectric properties of InSb crystals

Abstract: Modifications in the surface morphology and photoelectric properties of InSb crystals irradiated with nanosecond pulses of ruby laser are studied. The threshold energy density corresponding to the onset of surface melting was determined to be 0.14 J/cm2. Laser-induced changes in the spectra and photoconduction kinetics are analyzed. It is demonstrated that the irradiation of InSb crystals with ruby laser pulses within a certain range of energy densities slows down the surface recombination, increases the nonequilibrium carrier lifetime, and, as a consequence, enhances the photosensitivity of crystals.

Design of Touchscreen Control Unit for Medical Laser Systems

Abstract: The structure of the touchscreen control unit for medical ruby laser system was described.The produced mechanism and the transmitted ways of the electromagnetic interference(EMI) noises in ruby laser system were discussed,and the specific electromagnetic compatibility(EMC) methods for the problems were given.Key words:medical laser system; electromagnetic compatibility(EMC); switch mode power supply(SMPS); electromagnetic interference(EMI) filter

Rate equations for ruby and alexandrite Q-switched lasers

Abstract: To have a complex view on giant pulse generation, a more precise computer model of the build up Q-switch pulse in solid-state laser was realized. As a time starting point of the rate equation calculation, the moment of a flashlamp trigger was chosen. A system of three or four main differential rate equations describes the energy transfer from a pumping source - capacitor to an output giant pulse. Two laser active media, i.e. ruby and alexandrite, were examined with this model. A passive Q-switch ruby laser needs solving of the system of four differential equations; three differential equations gave the computer results for electro-optically Q-switched alexandrite laser.

Generation of Double Laser Pulses upon a Single Photoelectric Switching of a Branched Anisotropic Cavity by an Electrooptic Shutter

Abstract: The optical arrangement of a laser generating double giant pulses is described. Lasing is initiated upon a single photoelectric switching of a branched anisotropic cavity by an electrooptic shutter and using a bleachable filter. The time interval between laser pulses can be varied over a virtually unlimited range. The laser generates two giant pulses with mutually orthogonal planes of radiation polarization. The results of experimental investigations of a ruby laser of this kind based on active elements with a 60° orientation of the optical axis are presented.

Laser Treatments in Plastic Surgery and Dermatology

Abstract: The goal of skin resurfacing is the rejuvenation of the skin by stimulation of its regenerative potential. The outer layer of epidermis is ablated in order to improve the quality of the skin. Sun damage is removed and age-related changes are improved in skin resurfacing. In general, there are several methods for resurfacing procedures: mechanical, known as dermabrasion, chemical peel, electrical, known as radiowave ablation and photoablation, normally referred to as laser skin resurfacing. The difference between these procedures is the varying results, the side effects, the difficulty in performance and reproducibility. Laser skin resurfacing is a well-controlled and precise procedure that shows defined, predictable results with fewer risks of complications [10,15,40]. There are laser wavelengths suitable for laser skin resurfacing. One is the CO2 laser (10 600 nm) and the other is the Er:YAG (erbium:yttrium-aluminium-garnet) laser (2940 nm). The coefficient of absorption in water is more than 16 times higher in the EnYAG wavelength. This results in a more complete absorption in a thinner layer of tissue with ablation of up to 30 μm and a thermal damage zone of less than 50 μm.

An Increase in the Energy Yield and Efficiency of the Formation of Highly Coherent Giant Pulses in a Laser Resonator with Prism Reflectors

Abstract: Optical schemes of lasers with prism reflectors are described. Due to a change in the resonator geometry, an increased amount of radiation passes through in the active element, and a more complete use of the active-medium volume, these lasers make it possible to increase the efficiency of the formation of highly coherent giant pulses upon the self-injection of the initiating radiation and double giant pulses after a single photoelectric switching on of an active shutter. The radiation parameters of this type of ruby laser with self-injection of free-running or giant-pulse initiating radiation has been studied experimentally. A two-pass laser scheme allows for an almost twofold increase in the energy of giant pulses (at a level of ∼0.01 J).

Laser-plasma interaction in the resonator at the nanostructuring of solid surface by 0.69-/spl mu/M laser

Abstract: The temporal shape of ruby laser pulse is experimentally investigated in the cavity typical for the intracavity processing of Al-film evaporated on the glass substrate. This results in forming of the train of nanosecond pulses with nearly 100% modulation. It is shown the possibility to form nanosized periodic surface structures by single-pulse ruby laser treatment