Home  About us  Contact
 

High Repetition Rate (high + repetition_rate)

Distribution by Scientific Domains
Physics and Astronomy42%

Selected Abstracts

Continuous wave and passively Q-switched laser performance of the mixed crystal Nd:Lu0.15Y0.85VO4

LASER PHYSICS LETTERS, Issue 5 2010
S. Zhang
Abstract Laser characteristics of a novel mixed laser crystal Nd:Lu0.15Y0.85VO4 was investigated. It is attractive for Q-switching with high repetition rate and short pulse width due to its suitable stimulated emission cross-section and short upper level lifetime. Continuous wave (CW) output power of 8.18 W was obtained at the pump power of 18.9 W, corresponding to the optical conversion efficiency of 43.3% and the slope efficiency of 47%. In the passive Q-switching operation, the minimum pulse width attained was 7.8 ns, with the pulse repetition frequency of 23.2 kHz, with the single pulse energy and peak power estimated to be 94.8 ,J and 12.2 kW, respectively. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Experimental study of sealed off operation of a high repetition rate TEA CO2 laser

LASER PHYSICS LETTERS, Issue 10 2006
M. J. Torkamany
Abstract Design and construction of a high repetition rate low average power TEA CO2 laser with ultra violet pre ionization is presented. Replacing thyratron with a high voltage semiconductor switch and magnetic pulse compressor considering the highest peak power achievable is investigated. When using semiconductors as main switch of laser excitation circuit the output energy and laser power is lower about 5,10% relative to thyratron excitation circuit but the sealed off operation of laser is more uniform. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

20-W average power, high repetition rate, nanosecond pulse with diffraction limit from an all-fiber MOPA system

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2008
Songtao Du
Abstract In this article, we report an all-fiber master oscillator power amplifier (MOPA) system, which can provide high repetition rate and nanosecond pulse with diffraction-limit. The system was constructed using a (2 + 1) × 1 multimode combiner. The Q-Switched, LD pumped Nd:YVO4 solid-state laser was used as master oscillator. The 976-nm fiber-coupled module is used as pump source. A 10-m long China-made Yb3+ -doped D-shape double-clad large-mode-area fiber was used as amplifier fiber. The MOPA produced as much as 20-W average power with nanosecond pulse and near diffraction limited. The pulse duration is maintained at about 15 ns during 50,175 kHz. The system employs a simple and compact architecture and is therefore suitable for the use in practical applications such as scientific and military airborne LIDAR and imaging. Based on this system, the amplification performances of the all-fiber amplifier is investigated. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2546,2549, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23770 [source]

Use of picosecond infrared laser for micromanipulation of early mammalian embryos

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 10 2009
Artashes V. Karmenyan
A high repetition rate (80 MHz) picosecond pulse (,2 psec) infrared laser was used for the inactivation (functional enucleation) of oocytes and two-cell mouse embryos and also for the fusion of blastomeres of two-cell mouse embryos. The laser inactivation of both blastomeres of two-cell mouse embryos by irradiation of nucleoli completely blocked further development of the embryo. The inactivation of one blastomere, however, did not affect the ability of the second intact blastomere to develop into a blastocyst after treatment. Laser inactivation of oocytes at Metaphase II (MII) stage and parthenogenetically activated pronuclear oocytes also completely blocked their ability for further development. Suitable doses of irradiation in cytoplasm region did not affect the ability of embryos and activated oocytes to development. The efficiency of laser induced fusion for blastomeres of two-cell embryos was 66.7% and all the tetraploid embryos developed successfully into blastocysts in culture. Our results demonstrate unique opportunities of the applications of a suitable infrared periodic pulse laser as a universal microsurgery tool for individual living cells. Mol. Reprod. Dev. 76: 975,983, 2009. © 2009 Wiley-Liss, Inc. [source]

PI3D processing of DLC coatings for different applications

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2008
S. A. Nikiforov
Abstract DLC (a -C:H) and Si-DLC coatings have been deposited on various materials (steel, aluminium, silicon, glass, polymers) using a 1-m3 interior-antenna ICP PI3D facility with HMDSO and toluene as precursors. For conformal treatment of 3-D workpiececs, a low-voltage (0.5 - 1) kV, high repetition rate (up to 70 kHz) pulsing was applied. However, DLC formation on dielectric substrates was performed at higher (2 - 10) kV voltage using short (1 - 1.5) ,s pulses to minimize surface charging. Coating adhesion was achieved by formation of multi layer structure comprising Si-containing buffer layer, transient layer, DLC layer with gradually increasing hardness, and top hard DLC. Film hardness was (5 - 20) GPa, and the deposition rate (4 - 0.5) ,m/h. DLC surface roughness was (0.7 - 60) nm and water contact angle 70° - 110° depending on process parameters which implies various applications. Batch processing of sliding parts, cutting tools, glass moulds was performed. Double-side DLC coating on polymer web eliminated its rolling up due to the coating stress. With novel ICP antenna the DLC processing is promising for large-scale nano pattern transfer technology. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effects of femtosecond laser irradiation on osseous tissues

LASERS IN SURGERY AND MEDICINE, Issue 3 2007
B. Girard DMD
Abstract Background and Objective Few studies have investigated femtosecond (fs) lasers for cutting bone tissue. Study Design/Materials and Methods A 775 nm, 1 kHz, 200 femtosecond, up to 400 µJ laser system was used to irradiate in vitro calcified cortical bone samples and bone tissue culture samples. Results The ablation threshold in cortical bone was 0.69±0.08 J/cm2 at 775 nm and 0.19±0.05 J/cm2 at 387 nm. Plasma shielding experiments determined that the ablation plume and the plasma significantly affect material removal at high repetition rates and appear to generate thermal transients in calcified tissue. Confocal analysis revealed intact enzymatic activity on the surface of cells immediately adjacent to cells removed by fs laser irradiation. Conclusions These experiments demonstrate that fs lasers used for bone tissue cutting do not appear to generate significant temperature transients to inactivate proteins and that cellular membrane integrity is disrupted for only a few cell layers. Lasers Surg. Med. 39:273,285, 2007. © 2007 Wiley-Liss, Inc. [source]