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Q-switched Nd (Q-switch + nd)
Selected AbstractsLow-Fluence Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser for Melasma with Pre- or Post-Treatment Triple Combination CreamDERMATOLOGIC SURGERY, Issue 6 2010SE-YEONG JEONG MD BACKGROUND Topical triple combination (TC) treatment is considered the primary approach to melasma. Recently, collimated low-fluence 1,064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser treatment has attracted attention as an alternative approach. OBJECTIVES To compare the clinical efficacy and adverse effects of low-fluence Q-switched Nd:YAG laser when performed before and after treatment with topical TC using a split-face crossover design. METHODS Thirteen patients with melasma received topical treatment with TC cream or 1,064-nm Q-switched Nd:YAG laser treatment on opposite sides of the face for 8 weeks, and then treatments were reversed for 8 weeks. Responses were evaluated using the Melasma Area and Severity Index scoring system, spectrophotometry measurements, and a subjective self-assessment method. RESULTS After 16 weeks, better results were seen in subjective assessments when laser treatment was used after 8 weeks of topical TC treatment than before usage of TC. There were no significant adverse effects with the laser treatments. CONCLUSIONS Laser treatment after topical TC cream was found to be safer and more effective than the post-treatment use of topical agents. The authors have indicated no significant interest with commercial supporters. [source] Successful Treatment of a Cosmetic Tattoo Using a Combination of LasersDERMATOLOGIC SURGERY, Issue 1 2004Karen Rebecca Suchin MD Background. Cosmetic tattoos are becoming more popular and are often composed of several colors. Tattoo pigments containing ferric oxide and titanium dioxide can change to a blue-black color after exposure to Q-switched lasers that can be permanent. Objective. Using a patient who presented with rouge tattoos on the cheeks as an example, we describe a useful approach to laser treatment of cosmetic tattoos. Methods. Test areas were done with the Q-switched Nd:YAG at both 532 and 1064 nm and with the pulsed-dye laser at 595 nm. Results. Although an immediate blue-black color change occurred after treatment with the Nd:YAG at 532 and 1064 nm, sequential treatments at 1064 nm produced a near complete clearance of the tattoos. The pulsed-dye laser was used to remove subtle pink tones. Conclusion. Performing small test areas before complete treatment and using several laser wavelengths throughout the course of therapy are essential to the successful treatment of cosmetic tattoos. [source] Treatment of Pigmented Hypertrophic Scars with the 585 nm Pulsed Dye Laser and the 532 nm Frequency-Doubled Nd:YAG Laser in the Q-Switched and Variable Pulse Modes: A Comparative StudyDERMATOLOGIC SURGERY, Issue 8 2002Leyda Elizabeth Bowes MD background. Pigmented hypertrophic scars are a difficult condition to treat. They may result from traumatic injuries or from surgical and cosmetic procedures. The 585 nm flashlamp-pumped pulsed dye laser (FLPDL) has been used to treat this condition, with significant improvement of varying degrees. It remains to be determined whether other laser modalities may have a similar or even greater success in the treatment of pigmented hypertrophic scars. objective. To determine the efficacy of the 532 nm frequency-doubled Nd:YAG laser in the treatment of pigmented hypertrophic scars as compared to the 585 nm FLPDL. methods. Six patients with pigmented hypertrophic scars and skin phototypes II,IV were chosen. A scar was selected for treatment in each patient and divided into four equal 2 cm segments. Three segments were each treated with a different laser modality and one was left untreated to serve as the control. A 585 nm FLPDL was used with an energy of 3.5 J, a pulse duration of 450 ,sec, and a 10 mm spot size. A 532 nm Q-switched frequency-doubled Nd:YAG laser was set to an energy of 2.8 J, a 10-nsec pulse, and a 3 mm spot size. The same 532 nm laser was set to the variable pulse mode to treat a 2 cm scar segment, with an energy of 9.5 J, a 10-msec pulse, and a 4 mm spot size. An average of 3.3 treatments were performed on each scar segment, at intervals of 4,6 weeks and long-term follow-up at 22 weeks. Treatment outcome was graded by a blind observer using the Vancouver General Hospital (VGH) Burn Scar Assessment Scale. A SigmaStat t -test was used to determine the statistical significance of the values obtained. results. Treatment of pigmented hypertrophic scars with the 532 nm Q-switched Nd:YAG laser led to a significant improvement of 38% in the VGH scores when compared to baseline (P = .005). The 585 nm FLPDL also had a favorable effect on the scars, with an average improvement of 36.1% in the VGH scores. There was no significant difference noted between the outcome of treatment with either of these two lasers. Treatment with the 532 nm variable pulse Nd:YAG laser led to a 19% improvement in the VGH scores of scars, which did not differ significantly from the 16.1% improvement observed in control scars on the last follow-up visit. No side effects or complications from treatment were noted or reported during the course of the study. At the conclusion of the study, five of six patients chose the segment treated with the 532 nm Q-switched Nd:YAG laser as the best segment overall. conclusion. The 532 nm Q-switched Nd:YAG laser and the 585 nm FLPDL offer comparable favorable results in the treatment of pigmented hypertrophic scars. The 532 nm Q-switched Nd:YAG laser may be preferred by patients particularly distressed by the dark color of their scars. [source] Areolar Cosmetic Tattoo Ink Darkening: A Complication of Q-Switched Alexandrite Laser TreatmentDERMATOLOGIC SURGERY, Issue 1 2002Sung-Eun Chang MD background and objective. Medical tattooing of the areola is widely performed in Korea. However, cosmetic tattoos containing flesh-tone, purple-red, and yellow dyes are sometimes resistant to Q-switched laser and may even become darker. method. Two Korean women in their 30s who had a mastectomy got light brown to red areolar medical tattoos but they were not satisfied with the shape and size of the tattoos. They underwent Q-switched alexandrite laser treatment with a 3 mm collimated beam at fluences of 7.5,8 J/cm2 in order to trim the irregular contour and reduce the diameter of the tattoos. results. Within 5 minutes a dark gray to black discoloration of the treated area was evident and remained dark for 6 weeks. Improvement was not noted after two further Q-switched Nd:YAG laser treatments. conclusion. Medical areolar tattoos should be approached with extra caution when attempting their removal with high-energy pulsed lasers such as Q-switched alexandrite laser and a small test site should be performed prior to treatment. [source] An Effective Treatment of Dark Lip by Frequency-Doubled Q-Switched Nd:YAG LaserDERMATOLOGIC SURGERY, Issue 1 2001Somyos Kunachak MD Background. Dark lip is a common cosmetic problem in Southeast Asia. There is no known effective treatment. Objective. To propose an effective method for treating dark lips of varying causes with frequency-doubled Q-switched Nd:YAG laser. Methods. Seventy patients with dark lip, of which 22 were congenital, 24 acquired, and 24 of uncertain cause, were treated by frequency-doubled Q-switched Nd:YAG laser at a fluence of 2,3.5 J/cm2 (mode 2.5 J/cm2) after application of topical anesthesia. The endpoint of treatment was complete clearance of the pigment. Follow-up time was 24,36 months (mean 29 months). Results. All patients attained complete clearance of the lesion after an average of 2.5 treatments in the congenital group, 2.2 treatments in the acquired group, and 1.8 treatments in the group with uncertain etiology. The mean (±SD) number of treatments required by the whole group was 2.1 ± 1.4. Recurrence was observed in one case of congenital origin 3 months after the last treatment. In the remaining cases, results persisted up to the time of follow-up. Herpes simplex reactivation was noted in one case 3 days after treatment. There was no dyschromia, scar formation, or change of skin texture. Conclusion. Dark lip can be effectively treated by frequency-doubled Q-switched Nd:YAG laser without major adverse effects. [source] Laser-induced breakdown spectroscopy for soil diagnosticsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2001J. Bublitz Summary Laser-optical measurements and fibre optics are potentially attractive tools for applications in soil science because of their great sensitivity and selectivity and their capabilities for on-line and in situ analysis. We have investigated laser-induced breakdown spectroscopy (LIBS) for the quantitative detection of metal ions on the surface of natural soil samples from two sites (Hohenschulen and Oderbruch, Germany). The LIBS technique allows the spatially resolved investigation of adsorption and desorption effects of ions in soil. A frequency doubled (532 nm) and Q-switched Nd:YAG laser with a pulse duration of 8 ns is focused on the soil surface and induces a plasma. Typical power densities are 150 mJ mm,2. The plasma emission is recorded in time and spectrally resolved by a gateable optical multichannel analyser (OMA). A delay time of about 500 ns between laser pulse and OMA gate was used to resolve single atomic and ionic spectral lines from the intense and spectrally broad light that is emitted by the plasma itself. The dependency of the LIBS signal of a single spectral line on the amount of water in the sample is investigated in detail. The results indicate that quenching of water in the plasma plume reduces the line intensities, while the interaction with aquatic colloids increases the intensity. The two processes compete with each other, and a non-linear correlation between measured line intensities and the amount of water in the sample is obtained. This is verified by a simple computer simulation and has to be taken into account for the quantitative interpretation of LIBS signals, e.g. when absolute concentrations are estimated. In the present investigation natural calcium concentrations <,2 ,g kg,1 were measured with the LIBS technique in the samples for the two test sites. In addition, measurements were made with dry and water-saturated BaCl2 mixed soil samples, and no significant difference in the detection limit for barium was obtained. [source] Treatment of post-inflammatory hyperpigmentation using 1064-nm Q-switched Nd:YAG laser with low fluence: report of three casesJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 10 2009SB Cho [source] Diode-pumped doubly passively Q-switched Nd:LuVO4 laser with Cr4+:YAG saturable absorber and GaAs output couplerLASER PHYSICS LETTERS, Issue 10 2009K. Cheng Abstract A diode-pumped doubly passively Q-switched Nd:LuVO4 laser with Cr4+:YAG saturable absorber and GaAs output coupler is realized. This laser can generate a shorter and more symmetric pulse profile when compared with pure GaAs. By using two Cr4+:YAG saturable absorbers with different small-signal transmissions T0 = 0.71 and T0 = 0.81, the maximum average output power are 1.15 W and 1.31 W at the incident pump power of 11.23 W, corresponding to optical conversion efficiencies of 10.2% and 11.7%. At the same incident pump power, the minimum pulse widths of 4.18 ns and 5.42 ns can be obtained at T0 = 0.71 and T0 = 0.81, respectively. The pulse repetition rate and the single-pulse peak power of the laser are also measured. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Over 8 W high peak power UV laser with a high power Q-switched Nd:YVO4 oscillator and the compact extra-cavity sum-frequency mixingLASER PHYSICS LETTERS, Issue 2 2009X.P. Yan Abstract A 8.2 W UV laser was reported with the compact extra-cavity sum-frequency mixing. The IR fundamental frequency source was a high power and high beam quality Q-switched Nd:YVO4 oscillator. 38Wfundamental frequency laser at 1064 nm was obtained at the pulse repetition rate of 450 kHz with the beam quality factors of M2x = 1.27, M2y = 1.21. The type I and type II phase-matched LBO crystals were used as the extra-cavity frequency doubling and mixing crystals respectively. At 38 kHz, 8.2 W UV laser at 355 nm was achieved with the pulse duration of 8 ns corresponding to the pulse peak power as high as 27 kW, and the optical-optical conversion efficiency from IR to UV was 25.6%. The output characteristics of the IR and the harmonic generations varying with the pulse repetition rate were also investigated detailedly. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Repetition rate continuously controllable passively Q-switched Nd:YAG bonded microchip laserLASER PHYSICS LETTERS, Issue 8 2007H. Lei Abstract A stable repetition rate continuously controllable passively Q-switched Nd:YAG bonded microchip laser is presented. A 0.8 mm-thickness 7 mm-diameter Nd:YAG crystal at 1.6 at.% is adapted as active medium and the saturable absorber for passively Q-switched pulse generating, a 0.2 mm-thickness 6.8-mm diameter Cr4+:YAG piece was thermal bonded into the Nd:YAG after primary optical contact. By using pulse pump and controlling the duty cycle of electric pulse and temperature of laser diode, a 1 W C-mount packaged fast-collimated laser diode, we can continuously achieve repetition rate from 1 kHz to 10 kHz as active Q-switched laser. The delay time at 10 kHz is 90 ,s, while the single pulse energy is 2.8 ,J with pulse width of 2 ns. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Transportation of nanosecond laser pulses by hollow core photonic crystal fiber for laser ignitionLASER PHYSICS LETTERS, Issue 11 2005A. H. Al-Janabi Abstract Laser ignition via hollow core photonic crystal fiber (PCF) as a delivery medium has been demonstrated in the present work. Minimum pulse energy from a Q-switched Nd:YAG laser of only 150 µJ was achieved to ignite rich fuel mixtures of methane-air. Aspheric lens of high numerical aperture has been used to focus the laser beam. Different air/fuel ratios have been examined with different gas temperatures. The results indicate the feasibility of using hollow core PCF for high power beam transmission for laser ignition applications. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Diode pumped 500-picosecond Nd:GdVO4 Raman laserLASER PHYSICS LETTERS, Issue 5 2004T. T. Basiev Abstract Self-Raman frequency conversion in a diode-pumped passively Q-switched Nd:GdVO4 laser has been demonstrated. The use of LiF:F,2 crystal as a saturable absorber has provided effective Q-switching of the Nd:GdVO4 laser with high pulse energy. The laser pulse duration at the 1st Stokes wavelength 1174 nm was as short as 500 ps. Diode-to-Raman optical conversion efficiency more than 2 % at the pulse peak power of 9 kW was achieved. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Photodamage therapy using an electro-optic q-switched Nd:YAG laserLASERS IN SURGERY AND MEDICINE, Issue 8 2010Dina Yaghmai MD Abstract Background and Objective Q-Switched Nd:YAG lasers produce photoacoustic effects in addition to photothermal effects which may allow for greater tissue collagen production. The objective of the study is to determine the effectiveness and tolerability of an Electro-Optic (EO) Q-switched Nd:YAG laser with Single Pulse and novel Double Pulse (DP) options in the treatment of photodamaged skin. Materials and Methods Sixteen subjects with photoaging were enrolled in this prospective, randomized, split-faced study. Subjects received 6 bi-weekly laser treatments. One half of the face was treated with a Single Pulse while the other half was treated with energies divided into a DP. Blinded investigators and subjects assessed improvement after the sixth treatment for wrinkles, coarseness, pigmentation, redness, laxity, comedones, pore size, and overall skin condition. Subjects also rated the tolerability of the treatments. Results For the Single Pulse side of the face, the investigators rated 33% of the patients as having a good to excellent (51% or greater) improvement in the overall condition of the skin while 47% of the subjects reported these levels. On the DP side, the overall improvement was good to excellent at a 27% rate by the investigators and 54% by the subjects. Distributions of improved ratings among investigators and subjects were similar for both sides of the treatment area. The majority of stinging/burning sensations during treatment were reported as mild on the DP side (62.8%) and moderate (63.8%) on the Single Pulse side. The chance of reporting none or only mild stinging/burning sensation during treatment was four times greater on the side of the face treated with the DP (P,<,0.0001). Conclusions Results have shown that treatment with the EO QS Nd:YAG laser provides a safe and effective method of skin rejuvenation with the additional benefit of significantly lower patient discomfort during use of the DP mode. Lasers Surg. Med. 42:699,705, 2010 © 2010 Wiley-Liss, Inc. [source] Long-term fine caliber hair removal with an electro-optic Q-switched Nd:YAG Laser,LASERS IN SURGERY AND MEDICINE, Issue 8 2010Abnoeal D. Bakus PhD Abstract Background In spite of major advances in hair removal therapy, fine caliber hair remains a significant challenge for laser- and light-based devices. Objective Evaluate a novel Electro-Optic (EO) Q-switched Nd:YAG laser for pigmented fine caliber hair removal in the Standard Single and a double pulse (DP) mode. Methods Eleven patients underwent four laser treatments at monthly intervals. Bilateral anatomical regions received to one side the standard single pulse (SSP) while the other side the DP option. Blinded investigators conducted hair counts at 6 months post-treatment and after 24 months. Patients assessed hair loss and discomfort. Six patients rated their satisfaction at 6 months. Results At 6 months, investigators found a reduction of 50% in hair counts with the DP and 46% with standard pulse. Ninety percent in DP and 50% in SSP reported none to mild discomfort. Transient erythema and edema was observed with a lower severity rating with the DP. There were no other untoward effects. 83.3% of patients who completed the study at 6 months expressed satisfaction with the results. At 24 months hair loss was maintained at the same rate. Conclusion The EO Q-switched Nd:YAG laser is an effective option for the permanent treatment of unwanted fine hair and has a high-patient satisfaction rate. There is less therapeutic discomfort in the DP mode. Lasers Surg. Med. 42:706,711, 2010 © 2010 Wiley-Liss, Inc. [source] Efficacy of laser treatment of tattoos using lasers emitting wavelengths of 532 nm, 755 nm and 1064 nmBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2004B.M. Prinz Summary Background Multifunctional laser devices can be used to treat tattoos successfully. Objectives To report the efficacy of laser treatment in professional, amateur, accidental and permanent make-up tattoos from our own experience and to compare it with the literature. Methods We retrospectively studied 74 consecutive patients with professional, amateur, make-up and accidental tattoos between June 1998 and November 2000. Patients were treated with a Q-switched Nd:YAG laser (wavelengths of 532 nm and 1064 nm), a Q-switched alexandrite laser (755 nm) and a variable pulse Nd:YAG laser (532 nm). Results Fourteen patients (19%) achieved a complete response (> 95% lightening of treated tattoos), 23 (31%) an excellent response (76,95% lightening) and 21 (28%) a good response (51,75% lightening). Sixteen patients (22%) showed only a slight improvement (, 50% lightening). Make-up tattoos and blue,black professional tattoos were most successfully treated. Multicoloured professional tattoos needed more treatments (mean ± SD 5·7 ± 5·4) in comparison with single-colour tattoos (3·5 ± 2·0). The amateur tattoos needed fewer treatments (2·8 ± 1·1) in comparison with professional tattoos. With accidental tattoos the results depended on the particles which had penetrated the skin. In contrast to literature reports, newer tattoos showed a trend to better treatment results than older tattoos. Conclusions Using modern Q-switched lasers, tattoos are removed successfully with minimal risk of scarring and permanent pigmentary alterations. Even multicoloured tattoos can be treated successfully and with a low rate of side-effects. [source] Effect of laser cleaning on granite colorCOLOR RESEARCH & APPLICATION, Issue 2 2007Carlota M. Grossi Abstract This article presents the effect of laser radiation on the color of ornamental granites used for external cladding. The laboratory experimentation was undertaken on a widely used coarse-grain granite commercially known as Rosa Porriño. The irradiation was carried out with a Q-switched Nd:YAG laser at 1064 nm and several energy densities (fluences) on polished surfaces, dry and wet, uncoated, and artificially coated-simulating a black crust. Laser effects on the granite surface were determined by color measurements with a colorimeter. These measurements made possible to determine probable damage due to laser radiation and the diverse response of different minerals. The analysis of the data also suggests potential causes for the color change and applicability limits of the technique. The a*-parameter, or red,green component, is the most affected, leading to a change in hab (hue) and was interpreted as a result in variations in the Fe compounds, which strongly condition stone color. No significant changes in L* (luminosity or lightness) or Cab* (chroma) may indicate no relevant alterations in the surface polish. When using laser irradiation to remove black layers on granite surfaces, variations of L* can be indicative of the cleaning effectiveness. This research results may be useful to select laser parameters when managing ornamental granite cleaning operations. However, they also suggest the need of further experimentation in specific techniques of analysis as well as different laser wavelengths. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 152 , 159, 2007 [source] | ||||||||||