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Laser Operating (laser + operating)
Selected AbstractsEfficacy of the Flashlamp-Pumped Pulsed-Dye Laser in Nonsurgical Delay of Skin FlapsDERMATOLOGIC SURGERY, Issue 7 2003Ali Riza Erçöçen MD Objective. The purpose of this article was to determine the effectiveness of laser delay by use of the flashlamp-pumped pulsed-dye laser operating at a wavelength of 585 nm; to elucidate the comparable or dissimilar macroscopic, microscopic, and hemodynamic changes between laser and surgical delay methods; and to clarify the possible mechanisms underlying the delay effect of laser. Methods. A standardized caudally based random dorsal rat flap model was used in this study: Acute random skin flaps served as control subjects (group 1). Surgical delay was employed by incision of lateral longitudinal borders both without (group 2) and with (group 3) undermining, and laser delay methods were performed by laser irradiation of both lateral longitudinal borders (group 4) and the entire surface (group 5) of the proposed flap. Evaluation was done by histologic examination, India ink injection, laser Doppler perfusion imaging, and measurement of flap survival. Results. Histologically, dilation and hypertrophy of subpapillary and subdermal vessels were evident in groups 2, 3, and 4; on the other hand, degranulation of mast cells in the vicinity of occluded vessels at the 1st hour of laser delay and a striking mast cell proliferation and degranulation in association with newly formed vessels (angiogenesis) at the 14th day of laser delay were prominent in group 5. India ink injections revealed longitudinally arranged large-caliber vessels and cross-filling between the vessels of adjacent territories in groups, 2, 3, and 4, but only small-caliber vessels in group 5. Compared with the acute flaps, both surgical and laser delay significantly increased the mean flap perfusion to the maximal levels after a 14-day delay period, and all delay procedures improved flap survival; the most significant increase in surviving area was observed in group 3, whereas the less significant increase in surviving area was in group 5. Conclusion. This study demonstrates that laser delay is as effective as surgical delay and that laser delay by lasering lateral borders leads to dilation and longitudinal rearrangement of the existing vessels rather than angiogenesis, whereas laser delay by lasering the entire surface results in delay effect by inducing angiogenesis due to activation and degranulation of the mast cells. [source] Mode-locked Yb-doped large-mode-area photonic crystal fiber laser operating in the vicinity of zero cavity dispersionLASER PHYSICS LETTERS, Issue 3 2010Y.-J. Song Abstract A passively mode-locked ytterbium-doped largemode-area photonic crystal fiber oscillator operating in the vicinity of zero cavity dispersion is demonstrated. The self-starting mode-locking operation is achieved by a high contrast saturable absorber mirror. Two mode-locking regimes with opposite signs of net cavity dispersion are investigated. At a net cavity dispersion of ,0.0035 ps2, the fiber laser directly generates 10-nJ laser pulses with an average power of 630 mW at 65.3 MHz repetition rate. The pulses can be dechirped to 78 fs by extracavity dispersion compensation. The pulse energy is scaled up to 18 nJ, yielding an average power of 1.2 W, when the cavity dispersion is set at 0.0035 ps2. In this regime, the laser output can be extracavitydechirped to 120 fs. Dynamics of pulse evolution in the fiber laser is illustrated by numerical simulation, which agrees well with experimental results. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Experimental study of a high-power CW diode-sidepumped Nd:YAG rod laserLASER PHYSICS LETTERS, Issue 9 2005F. Hajiesmaeilbaigi Abstract In this paper we report on the characterization of a diode-side-pumped Nd:YAG rod laser operating at 300 W CW output power. The simulated and measured pump energy distributions in the crystal are compared. The thermal lens effect of the Nd:YAG have been experimentally investigated, and its influence on the performance of the laser are discussed. Output power and the beam quality of the laser under different resonator mirrors and rod end-face curvatures have been experimentally studied. The optical-to-optical and electrical-to-optical efficiencies are 28.5% and 11%, respectively. The beam parameter product is 40 mm · mrad and the instability of laser is about 3%. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Ultrasound guidance and monitoring of laser-based fat removalLASERS IN SURGERY AND MEDICINE, Issue 10 2008Jignesh Shah MS Abstract Background and Objectives We report on a study to investigate feasibility of utilizing ultrasound imaging to guide laser removal of subcutaneous fat. Ultrasound imaging can be used to identify the tissue composition and to monitor the temperature increase in response to laser irradiation. Study Design/Materials and Methods Laser heating was performed on ex vivo porcine subcutaneous fat through the overlying skin using a continuous wave laser operating at 1,210 nm optical wavelength. Ultrasound images were recorded using a 10 MHz linear array-based ultrasound imaging system. Results Ultrasound imaging was utilized to differentiate between water-based and lipid-based regions within the porcine tissue and to identify the dermis-fat junction. Temperature maps during the laser exposure in the skin and fatty tissue layers were computed. Conclusions Results of our study demonstrate the potential of using ultrasound imaging to guide laser fat removal. Lasers Surg. Med. 40:680,687, 2008. © 2008 Wiley-Liss, Inc. [source] Tunable medium power multiwavelength fiber laserMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2009Mansour Dastmalchi Abstract The authors report a medium power spacing tunable multiwavelength fiber laser operating at room temperature. A double-clad erbium-ytterbium co-doped fiber was used to produce high output power. An unpumped polarization-maintaining fiber and a Lyot-Sagnac loop filter with multiple segments of polarization-maintaining fibers were used as a saturable absorber to stabilize the laser wavelengths and tunable filter to tune the separation between lasing wavelengths, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2517,2519, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24648 [source] Astrophysical laser operating in the O i 8446-Å line in the Weigelt blobs of , CarinaeMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005S. Johansson ABSTRACT Within the framework of a simple model of photophysical processes in the Weigelt blobs in the vicinity of the luminous blue variable (LBV) star , Carinae, we explain the presence of the fluorescent ,O i, 8446-Å and forbidden [O i] 6300-Å lines as well as the absence of the allowed O i 7774-Å line in spectra recorded with the Hubble Space Telescope (HST)/STIS instrument (Gull et al.). From atomic data and estimated stellar parameters we demonstrate that there is a population inversion and stimulated emission in the 3p 3P,3s 3S transition ,8446 due to photoexcitation by accidental resonance (PAR) by H Ly, radiation. [source] Green monolithic II,VI vertical-cavity surface-emitting laser operating at room temperaturePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2004C. Kruse Abstract The realization of a monolithic all II,VI-based vertical cavity surface emitting laser (VCSEL) for the green spectral region is reported. Optically pumped lasing operation was achieved up to room temperature using a planar VCSEL structure. Taking advantage of distributed Bragg-reflectors based on MgS/Zn(Cd)Se superlattices as the low-refractive index material and ZnS0.06Se0.94 layers as the high-index material with a refractive index contrast of ,n = 0.6, a quality factor exceeding Q = 2000 is reached by using only 18 Bragg periods for the bottom DBR and 15 Bragg periods for the top DBR. The threshold power density is 0.32 MW/cm2 at a temperature of 10 K (emission wavelength 498.5 nm) and 1.9 MW/cm2 at room temperature (emission wavelength 502.3 nm). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||