Showing papers on "Ruby laser published in 1996"

Method and apparatus for skin rejuvenation and wrinkle smoothing

Abstract: A method and apparatus for treating skin includes applying pulsed light to the skin to heat and shrinking collagen within the skin, thereby reviving the elasticity of the collagen and of the skin. The epidermis and outer layers of the skin may be protected by cooling with a transparent substance, such as ice or gel, to the skin. The temperature distribution within the skin is controlled by controlling the delay between the time the coolant is applied, and the time the light is applied, by controlling the pulse duration and applying multiple pulses, and by filtering the light and controlling the radiation spectrum, preferably, the spectrum includes light having a wavelength in the range of 600-1200nm. The pulsed light may be incoherent, such as that produced by a flashlamp, or coherent, such as that produced by a Nd(Yag) laser or a ruby laser, and may be directed to the skin using a flexible or rigid light guide. Also, a method and apparatus for cutaneous resurfacing including directing Er:YAG laser light to the skin. The light may be pulsed, preferably with a delay of about 0.5-l0msec between pulses. In one embodiment the pulses have energy fluences of preferably about 100J/cm2.

Clinical dental application of Er:YAG laser for Class V cavity preparation.

Abstract: Following the development of the ruby laser by Maiman in 1960, the Nd:YAG laser, the CO2 laser, the semiconductor laser, the He-Ne laser, excimer lasers, the argon laser, and finally the Er:YAG laser capable of cutting hard tissue easily were developed and have come to be applied clinically. In the present study, the Er:YAG laser emitting at a wavelength of 2.94 microns developed by Luxar was used for the clinical preparation of class V cavities. Parameters of 8 Hz and approx. 250 mJ/pulse maximum output were used for irradiation. Sixty teeth of 40 patients were used in this clinical study. The Er:YAG laser used in this study was found to be a system suitable for clinical application. No adverse reaction was observed in any of the cases. Class V cavity preparation was performed without inducing any pain in 48/60 cases (80%). All of the 12 cases that complained of mild or severe intraoperative pain had previously complained of cervical dentin hypersensibility during the preoperative examination. Cavity preparation was completed with this laser system in 58/60 cases (91.7%). No treatment-related clinical problems were observed during the follow-up period of approx. 30 days after cavity preparation and resin filling. Cavity preparation took between approx. 10 sec and 3 min and was related more or less to cavity size and depth. Overall clinical evaluation showed no safety problem with very good rating in 49 cases (81.7%).

Laser ablation–inductively coupled plasma mass spectrometry with a time-of-flight mass analyser

Abstract: Laser ablation has been employed for sample introduction into an ICP-time-of-flight (TOF) mass spectrometer. The transients generated by the ablated material are generously sampled by the 10 kHz repetition rate of the TOF instrument. A detection limit of 10 ppb for Pb in a cast-iron standard is calculated from integration of a 0.3 s transient signal generated by a single laser pulse. By simultaneously acquiring and rationing the signals from two isotopes of Zn, the substantial pulse-to-pulse power fluctuations from the laser are virtually eliminated. Although some of the data are presented in a single- or double-channel acquisition mode, the results demonstrate the sensitivity and rationing abilities available for all elements and isotopes simultaneously from a single laser pulse. Use of a digital oscilloscope provides a full elemental spectrum for each laser pulse as the laser is rastered across a lava sample that contains plagioclase crystals. The relative spatial distributions for 11 elements of interest contained in this sample are plotted over an 11 mm distance. This paper is not intended to be a display of state-of-the-art laser-ablation techniques, as the large beam divergence of the ruby laser limits the spatial resolution to 1 mm. However, the ability of the plasma-source TOF mass spectrometer for analysing transient signals is clearly demonstrated.

Minocycline‐induced pigmentation resolves after treatment with the Q‐switched ruby laser

Abstract: Four patients with minocycline-induced cutaneous pigmentation were treated with the Q-switched ruby laser. The pigmentation resolved and there was no adverse effects.

Q-switched ruby laser treatment of oculodermal melanosis (nevus of Ota).

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- to 40-ns pulse duration produced by this laser approximates the thermal relaxation tim

Apparatus for skin rejuvenation and wrinkle smoothing

Abstract: of EP0763371A method and apparatus for treating skin includes applying pulsed light to the skin to heat and shrinking collagen within the skin, thereby reviving the elasticity of the collagen and of the skin. The epidermis and outer layers of the skin may be protected by cooling with a transparent substance, such as ice or gel, to the skin. The temperature distribution within the skin is controlled by controlling the delay between the time the coolant is applied, and the time the light is applied, by controlling the pulse duration and applying multiple pulses, and by filtering the light and controlling the radiation spectrum, preferably, the spectrum includes the light having a wavelength in the range of 600-1200nm. The pulsed light may be incoherent, such as that produced by a flashlamp (301), or coherent, such as that produced by a Nd(Yag) laser or a ruby laser, and may be directed to the skin using a flexible or rigid light guide (305). Also, a method and apparatus for cutaneous resurfacing including directing Er:YAG laser light to the skin. The light may be pulsed, preferably with a delay of about 0.5-10msec between pulses. In one embodiment the pulses have energy fluences of preferably about 100J/cm .

Epidermal melanin absorption in human skin

Abstract: The principle of laser induced selective photothermolysis is to induced thermal damage to specific targets in such a manner that the temperature of the surrounding tissue is maintained below the threshold for thermal damage. The selectivity is obtained by selection of a proper wavelength and pulse duration. The technique is presently being used in the clinic for removal of port-wine stains. The presence of melanin in the epidermal layer can represent a limitation to the selectivity. Melanin absorption drops off significantly with increasing wavelength, but is significant in the entire wavelength region where the blood absorption is high. Treatment of port-wine stain in patients with high skin pigmentation may therefore give overheating of the epidermis, resulting in epidermal necrosis. Melanosomal heating is dependent on the energy and duration of the laser pulse. The heating mechanism for time scales less than typically 1 microsecond(s) corresponds to a transient local heating of the individual melanosomes. For larger time scales, heat diffusion out of the melanosomes become of increased importance, and the temperature distribution will reach a local steady state condition after typically 10 microsecond(s) . For even longer pulse duration, heat diffusing from neighboring melanosomes becomes important, and the temperature rise in a time scale from 100 - 500 microsecond(s) is dominated by this mechanism. The epidermal heating during the typical 450 microsecond(s) pulse used for therapy is thus dependent on the average epidermal melanin content rather than on the absorption coefficient of the individual melanosomes. This study will present in vivo measurements of the epidermal melanin absorption of human skin when exposed to short laser pulses (< 0.1 microsecond(s) ) from a Q-switched ruby laser and with long laser pulses (approximately 500 microsecond(s) ) from a free-running ruby laser or a long pulse length flashlamp pumped dye laser. The epidermal melanin absorption coefficient of human skin of various pigmentation and races will be presented.

Two-wavelength contouring with a pulsed ruby laser by employing TV-holography

Abstract: A two-wavelength surface contouring system based on electronic speckle pattern interferometry (ESPI) with a pulsed ruby laser is reported. Two states of the test object were recorded at different wavelengths of the laser. The wavelength change was controlled by altering the temperature of the output etalon. The phase information of the surface contour can be obtained by using either the sinusoid fitting method or the Fourier transform method. Contour intervals of about 14 mm and 7 mm are available.

An Investigation on the Behavior of Laser Induced Bubble in Cryogenic Liquid Nitrogen

Abstract: There have been few experimental reports on cryogenic two-phase fluids and cavitation phenomena using the irradiation of pulsed high-power laser This paper describes an investigation of the behavior of laser induced cavitation bubble in cryogenic liquid nitrogen The bubble is produced by a pulsed ruby laser focused in the special cryostat The production, growth, and rebound phenomena of the bubbles are visualized by diffusive shadowgraph technique with an image-converter camera To compare with the experimental results, a numerical study has also been performed on the dynamics of a single spherical bubble in liquid nitrogen under the conditions of nonequilibrium phase change

Fiber-optic transmission of stretched pulses from a Q-switched ruby laser

Abstract: Fiber-optic transmission of Q-switched ruby laser pulses is limited by fiber damage owing to the high laser-beam intensities. Pulse stretching with a semiconductor-based control circuit for the Pockels cell of the ruby laser to reduce the peak intensities is described. Pulses with durations from 200 ns to 1 μs and a coherence length of ~3 m were generated. These pulses were coupled into multimode optical fibers to investigate the transmission characteristics and the limits of transmittable pulse energies. Stretched pulses can be transmitted in quartz fibers with a 600-μm core diameter to pulse energies of 300 mJ, which is an increase by a factor of 4 compared with standard Q-switched pulses. It is expected that beam guiding of ruby laser pulses by fiber optics will significantly facilitate the use of holographic interferometry in technical applications such as vibration analysis.

Dynamics of laser-produced carbon plasma

Abstract: Carbon plasmas produced by radiation from a ruby laser (wavelength 694.3 nm) focussed onto a carbon target in vacuum are studied spectroscopically with a time resolution of 40 ns. Measured line profiles of several ionic species (CI-CIV) were used to infer electron density and temperature at several positions above the target surface as function of time elapsed after the beginning of the laser pulse. The particle density at several positions above the target surface as function of time was judged from corrected line intensities. Experimental data are compared with theoretical predictions made with the effusion model of plasma expansion (Kelly R and Braren B 1991 Appl. Phys. B 53 160). The effusion model provided the relative particle density in the expanding plasma cloud as a function of initial target temperature. By comparing predicted and measured time evolution of particle density, an initial target temperature of about 125eV was inferred. The coupling of the laser beam energy to the plasma itself was inferred from the failure of the model of the direct target surface heating (Andreic Z, Henc-Bartolic V and Kunze H-J 1993 Physica Scripta 48 331) to produce the required target temperature.

Generating and recording transient bending waves in plates by pulsed lasers

Abstract: We have presented a method to generate bending waves in a plate by focusing a Q-switched Nd:YAG-laser pulse on its surface. These waves are recorded by double pulsed hologram interferometry. Evaluation of the interferograms show that the bending wave pattern is very similar to what is predicted by the Kirchhoff plate equation assuming a point impact of infinitesimally short duration. This indicates that a short Nd:YAG-laser pulse may be considered as a Dirac pulse in space and time. Future investigations will be performed with a more powerful and “cleaner” laser to get a higher energy and impulse transfer to the plate thus giving bending waves of larger amplitude. Promising preliminary experiments have also begun using a double pulsed ruby laser both for generating and recording of bending waves.

Tattoo formation from absorbable synthetic suture and successful removal with Q-switched ruby laser

Abstract: background Traumatic tattoos result from accidental or unintentional deposition of exogenous pigment within injured skin. Pigments may consist of heavy metals, vegetable matter, or commercial dyes. objective The clinical and histologic description of a traumatic tattoo resulting from a surgical procedure using undyed, braided, synthetic, absorbable suture material and its removal with the Q-switched ruby laser (694 nm, 28 nsec). methods The pigmented linear lesion was biopsied and processed using standard histological methods. Subsequently, the area was treated on two occasions with the Q-switched ruby laser. results The pigmented lesion was completely removed with the Q-switched laser treatments. conclusion We report on the occurrence of a traumatic tattoo resulting from synthetic suture material and complete removal with the Q-switched ruby laser.

Solid state polymer dye Q-switch for Cr:LiCAF, alexandrite, and ruby lasers

Abstract: HITCI doped organically modified silicate (ORMOSIL) is demonstrated to be an effective dye Q-switch for the Cr:LiCAF, alexandrite, and ruby lasers.

Attempt to obtain greater dermal depth of vascular injury using dye-enhanced laser technique: A new approach

Abstract: Background and Objective Although pulsed dye laser has been successfully used in the treatment of portwine stains, a number of patients had incomplete clearance because the depth of penetration by the pulsed dye laser was inadequate. This study was performed to establish the greater penetration depth of vascular injury using a dye-enhanced laser technique. Study Design/Materials and Methods The ruby laser at 694.3 nm was used, and the corresponding specific dye was Prussian blue solution (maximum absorbance 694 nm). We compared the penetration depth of vascular injury by the ruby laser irradiation after the Prussian blue injection with that by the dye laser irradiation. A flashlamp dye laser with a pulse duration of 300 μsec and a 5 mm diameter spot size was used to 6.2 J/cm2 at 590 nm. The Prussian blue solution was injected into the superficial epigastric artery of white male Japanese rabbits, immediately followed by the ruby laser exposure to 6.2 J/cm2 at a pulse duration of 283 μsec in a 15 × 15mm spotsize. Depth of penetration was measured from the dermoepidermal junction to the deepest site of vascular injury at 24 hours after laser exposure. Results Mean penetration of 590 nm of the dye laser light was 1.45 mm; mean penetration of the 694.3 nm ruby laser irradiation after the Prussian blue injection was 2.33 mm. Ruby laser penetration was greater than that of the dye laser. Conclusion This study emphasizes that the ruby laser irradiation after the Prussian blue injection can induce deeper vascular injury than the dye laser inducing similar pathological changes. © 1996 Wiley-Liss, Inc.

Schmutztätowierungen Entfernung durch den gütegeschalteten Rubinlaser

Abstract: The Q-switched ruby laser (wave length 694 nm; pulse durations 25 ns or 40 ns) cause selective damage to natural and artificial skin pigments. Treatable lesions include benign pigmented growths (benign, lentigo, ephelides, cafeau-lait spots and Becker's nevi), as well as amateur and professional tattoos. The Q-switched ruby laser is also very effective in the treatment of traumatic tattoos. We report our experiences with two patients whose traumatic tattoos resolved completely without any scarring after ruby laser therapy. Our findings show that Q-switched ruby laser treatment may represent the therapy of choice for these tattoos.

[The ruby laser: can removal of pigmented skin changes with the ruby laser be done by non-physician personnel?].

Abstract: Chromophores of the skin, especially melanin and exogenous pigments (e.g., tattoos), absorb red ruby laser light (694 nm) comparatively well. Selective photothermolysis of melanin, melanosomes, and tattoo particles theoretically leads to clearing or removing of cutaneous pigmented lesions and tattoos. The excellent cosmetic results after ruby laser treatment are leading to the increasingly widespread use of these costly laser systems. Not only physicians, but also cosmeticians and masseurs work with ruby lasers to remove tattoos and cutaneous pigmented lesions, often without correct dermatological diagnosis. An ever-increasing number of patients present themselves at our department with nevi previously treated with ruby laser. The dimensions and potential sequelae of these treatments are still unknown. Therefore, we present the principles of ruby laser treatment and its indications, side effects, and the main risks.

Frequency-stabilized high-power ruby laser Q switched by Rb 2 vapor

Abstract: Passive Q switching of a ruby laser by the use of molecular rubidium (Rb2) vapor has been realized. For the first time, to our knowledge, an integrally sapphire cell containing Rb2 vapor was used as the saturable absorber, which ensures an operation period of several years. Single-frequency-stabilized giant pulses with 700-mJ energy, 22-ns duration, and 200-MHz spectral width were obtained.

Longitudinal mode selection in a dye Q-switched ruby laser: a comparison between theoretical and experimental results

Abstract: This paper provides a mathematical analysis to calculate the number of longitudinal modes and their relative strength in a dye Q-switched ruby laser. The calculations were based on formulae developed to accurately predict the number of loop transmits that occur while the laser pulse builds up from noise levels. An experiment was carried out using a ruby laser set-up to confirm our theoretical predictions. The number of longitudinal modes present in the laser output was evaluated by recording holograms of a two meter long graduated panel using the same laser source. The end results closely matched our theoretical predictions. This proven mathematical analysis was then applied to our laser design to optimize the longitudinal mode selection property of the dye Q-switch in the laser. As a result, the developed ruby laser produced single longitudinal mode pulses at a probability of 98%.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Rubinlaser : Ist die Entfernung von pigmentierten Hautveränderungen mit dem Rubinlaser durch Nichtärzte möglich ?

Abstract: Chromophores of the skin, especially melanin and exogenous pigments (e.g., tattoos), absorb red ruby laser light (694nm) comparatively well. Selective photothermolysis of melanin, melanosomes, and tattoo particles theoretically leads to clearing or removing of cutaneous pigmented lesions and tattoos. The excellent cosmetic results after ruby laser treatment are leading to the increasingly widespread use of these costly laser systems. Not only physicians, but also cosmeticians and masseurs work with ruby lasers to remove tattoos and cutaneous pigmented lesions, often without correct dermatological diagnosis. An ever-increasing number of patients present themselves at our department with nevi previously treated with ruby laser. The dimensions and potential sequelae of these treatments are still unknown. Therefore, we present the principles of ruby laser treatment and its indications, side effects, and the main risks.

Traumatic tattooing : Treatment with the Q-switched ruby laser : A case study

Abstract: This case report details the successful treatment of extensive, facial traumatic tattooing in an adult male. The Q-switched ruby laser was utilized. It is demonstrated to be an excellent tool for the treatment of traumatic tattooing. The results achieved are superior to other methods and complications reported with other treatment options are minimized.

Infrared Semiconductor Laser by Means of J x H Force Excitation of Electrons and Holes

Abstract: In the earlier stage of the investigation of lasing action in solids, especially in semiconductors, the possibility of utilizing Landau levels was proposed by several investigators [1,2]. While these attempts were not successful, the first achievements of a ruby laser was reported by Maiman in 1960 [3]. In semiconductors, after the subsequent developments of injection-type semiconductor lasers [4], the research shifted to the lasing action by use of the quantum size effect in low-dimensional materials, such as quantum wires [5,6] and dots [5]: The principle is based on utilizing the singularity in the density of states of electrons associated with quantization, which produces discrete energy states due to the finite-size effect.

Highly efficient polymer passive switches for a ruby laser

Abstract: Stable highly efficient polymer passive switches were developed for a ruby laser. These switches were based on a polyurethane composite activated with polymethine dyes. The Q-switching efficiency of these switches was 55% in the single-pulse regime and 95% when bursts of giant pulses were generated. Single pulses of 600 mJ energy and 25 ns duration were generated. The service life of these polymer switches was at least 105 pulses.

Naevus flammeus : Keine Indikation für den Rubinlaser

Abstract: Chromophores of the skin, especially melanin absorb red ruby laser light (694 nm) quite well. Selective Photothermolysis of melanin, melanosomes and tattoo particles theoretically leads to clearing of cutaneous pigmented lesions and tattoos. Whether the absorption of red ruby laser light in hemoglobin is strong enough to destroy or occlude vessels in vascular lesions is clinically and histologically investigated in the following study. 10 patients with port-wine stains were treated with the q-switched ruby laser. Clearing of the port-wine stain was not observed in any of the patients. 2 Patients with skin type IV showed a slight hypopigmentation. Based on these results, ruby laser irradiation cannot be recommended for the treatment of port-wine stains.

Townes and Nonlinear Optics

Abstract: It was in the early 1960s, immediately after the development of the ruby and the helium-neon lasers that the first observations were made of optical harmonics, two-photon absorption, stimulated Raman and Brillouin scattering, and self-trapping and focusing of laser beams. This was an exciting period for nonlinear optics, and Charles Townes and his students and collaborators were major players in the exploration of this field of research.

Optical diagnostics of laser-induced melting and defect formation at the surface of cadmium telluride

Abstract: Modifications of structural, electrical and recombinational properties of CdTe under nanosecond pulse of ruby laser were studied by techniques of second harmonic generation, time resolved reflectivity, photoreflectance and photoluminescence. The threshold energy density necessary for surface melting Wm equals 40 +/- 5 mJ/cm2 was determined. Changes in linear reflection coefficient indicate intensive evaporation of the components at W > 90 mJ/cm2. Laser induced defect formation was registered after treatment with W > Wm. Apart from defect formation, the process of their annealing was detected in narrow area of energy near the melting threshold.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Q-switched ruby laser in cosmetic dermatology

Abstract: The q-switched ruby laser has shown promising results in the treatment of blue and black tattoos. The red light of the ruby laser, 694 nm wavelength, selectively absorbed by dark pigments, is converted into heat and pigments are immediately vaporized. Energy levels range between 4, 5 and 12 J/cm2. Short exposure time does not exceed the thermal relaxation time of the target structures. Thus, thermal damage of the surrounding tissue is minimal. Not only exogenous pigment as tattoo ink but also physiological pigmented structures as melanocytes, melanosome loaden keratinocytes, and melanophages are affected by this type of laser application. Therefore the ruby laser represents a new option in the treatment of a variety of benign pigmented lesions in cosmetic dermatology. The benefit of this source can be seen in efficient clearing of the lesions without scarring. As a side effect transient hypopigmentation may occur. Ruby laser treatment of melanocytic lesions cannot be recommended because unpigmented nevus cells do not absorb red light and persist unaltered. They still bear the potency of further transformation, as into malignancy.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.