The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Efim A. Khazanov - One of the best experts on this subject based on the ideXlab platform.
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Review of Faraday Isolators for Kilowatt Average Power Lasers
IEEE Journal of Quantum Electronics, 2014Co-Authors: Ilya L. Snetkov, Alexander V. Voitovich, Oleg V. Palashov, Efim A. KhazanovAbstract:Faraday isolators for high Average Power Lasers operating at room temperature are surveyed. Three devices on [001] oriented TGG crystals with the most known optical schemes are considered: traditional scheme, and schemes with compensation of thermally induced depolarization inside magnetic field and outside magnetic field. We report a unique 30-mm-aperture Faraday isolator with thermally induced depolarization compensation inside magnetic field. It provides 33.5-dB isolation ratio at 1.5-kW Average Laser Power.
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Magnetoactive media for cryogenic Faraday isolators
Journal of The Optical Society of America B-optical Physics, 2011Co-Authors: A. V. Starobor, D. S. Zheleznov, Oleg Palashov, Efim A. KhazanovAbstract:We analyzed a number of optical media, such as GGG, Nd:YAG, Yb:YAG, fused silica, CaF2, Yb:CaF2, and CdMnTe, that have not been used, to our knowledge, in the cryogenic Faraday isolator (FI) before. The temperature dependence of the Verdet constant and thermo-optical constants was experimentally investigated for λ=1.07 μm. We calculated the magneto-optical figure-of-merit and assessed the feasibility of using FI media with multikilowatt Average Laser Power.
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Faraday Rotators With Short Magneto-Optical Elements for 50-kW Laser Power
IEEE Journal of Quantum Electronics, 2007Co-Authors: D. S. Zheleznov, Efim A. Khazanov, I.b. Mukhin, Oleg Palashov, A.v. VoitovichAbstract:Faraday rotators with short magneto-optical elements are created and experimentally studied. The magneto-optical elements are made three to four times shorter either by cooling them to nitrogen temperatures or by increasing the magnetic field. These ways are shown to increase maximum Average Laser Power passing through the Faraday isolators up to 50 kW
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Slab-based Faraday isolators and Faraday mirrors for 10-kW Average Laser Power.
Applied Optics, 2004Co-Authors: Efim A. KhazanovAbstract:It is shown that the use of slabs instead of rods makes it possible to fabricate Faraday isolators and Faraday mirrors operating at a multikilowatt Power. Analytical dependences of thermally induced depolarization in Faraday devices on radiation Power and on slab aspect ratio have been obtained.
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Novel Faraday mirror for high-Average-Power application
ICONO 2001: Nonlinear Optical Phenomena and Nonlinear Dynamics of Optical Systems, 2002Co-Authors: Efim A. Khazanov, Alexey Anastasiev, N. F. Andreev, Oleg PalashovAbstract:A decrease in the depolarization ratio by more than an order of magnitude using a recently proposed Faraday mirror in comparison with the traditional Faraday mirror has been demonstrated in experiment. At a high Average Laser Power, the possibility of increasing the accuracy of compensation of depolarization in the active element by means of a (lambda) /4 plate using both the traditional and the novel Faraday mirror is shown.
Khalil Ibraheem Imhan - One of the best experts on this subject based on the ideXlab platform.
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Laser tube bending process for stainless steel 304
2017Co-Authors: Khalil Ibraheem ImhanAbstract:The invention of the Laser light in the mid-last-century has opened a wide spectrum of Laser material processing due to being unique, coherent and monochromatic. Moreover, the Laser forming process of materials has a potential feature to produce new shapes of sheets or tubes that cannot be achieved through conventional methods. In this study, the focus is placed on the Laser tube bending process because of its importance in large-term applications. Molds and dies are not currently in use; thus, no external forces that can cause tube bending defects such as wrinkling, wall thinning, springback and cross-section distortion. In addition, the process is flexible and can be controlled by Laser parameters, either individually or in combination with other processes. An analytical model is used to study the effect of the Average Laser Power, angular scanning speed, Laser beam diameter, and specimen geometry during the Laser tube bending process. The material specification impacts on the process behavior are analytically investigated for different material such as Copper, Aluminum, Nickel and Stainless Steel 304. To verify the analytical results, a high-Power pulsed Neodymiumdoped Yttrium Aluminium Garnet (Nd-YAG) Laser of the maximum Laser Power of 300 (W) emitted at 1064 nm with a fibre-coupled head is used to irradiate stainless steel 304 tubes with a 12.7 mm diameter, 0.6 mm thickness. A motorized rotational stage with computerized control is used to hold and rotate the specimen tube 180° for one semi-circle scanning, with a maximum angular scanning speed of 40 deg/sec. The deflection of the tube directly was measured to determine the bending angle, which it was 1.33 degrees when the Average Laser Power is 200 W and the angular scanning speed is 30 deg/sec. The study also discovered that the Laser softening heat treatment on the tube specimens can enhance the material absorption of the Laser light and the mechanical formability; hence, the bending angle produced is increased by 70%. The experimental results become higher than the analytical results as the Average Laser Power exceeds 100 W in both cases, with and without the Laser softening heat treatment. Thus, due to the rise of the specimen’s temperature, hence, the analytical model is modified and developed to involve the changes of material specifications by adding a factor to the model once the Laser Power becomes more than 100 W. This behavior may be due to the temperature rise of the tube material from the heat generated by the Laser. The modified model has been tested and optimized by using particle swarm optimization (PSO) to find the perfect specifications of the material affecting the Laser tube bending process such as thermal expansion coefficient, specific heat, yield stress, and absorption coefficient. The analytical and experimental results are in the same trend but with different slopes; the bending angle determined is directly proportional to the Average Laser Power, and inversely proportional to the angular scanning speed. Meanwhile, increasing the tube diameter and thickness reduces the value of the bending angle produced. In addition, the material specifications of the bent tube have significant effects on the process, especially the expansion coefficient which is directly proportional to the bending angle and the density as well as the specific heat which are inversely proportional with the bending angle.
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An Analytical and Experimental Investigation of Average Laser Power and Angular Scanning Speed Effects on Laser Tube Bending Process
MATEC Web of Conferences, 2017Co-Authors: Khalil Ibraheem Imhan, B. T. H. T. Baharudin, Azmi Zakaria, Mohd Idris Shah Ismail, Nasser Mahdi Hadi Alsabti, Ahmad K. AhmadAbstract:Laser tube bending is a new technique of Laser material forming to produce a complex and accurate shape due to its flexibility and high controllability. Moreover, the defects during conventional tube forming such as thinning, wrinkling, spring back and ovalization can be avoided in Laser tube bending process, because there is no external force used. In this paper an analytical investigation has been conducted to analyses the effects of Average Laser Power and Laser scanning speed on Laser tube bending process, the analytical results have been verified experimentally. The model used in this study is in the same trend of the experiment. The results show that the bending angle increased with the increasing of Average Laser Power and decreased with the increasing of angular scanning speed.
Alexander Aleksandrov - One of the best experts on this subject based on the ideXlab platform.
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Laser optics development for the Laser assisted H − beam stripping at Spallation Neutron Source
2011 International Quantum Electronics Conference (IQEC) and Conference on Lasers and Electro-Optics (CLEO) Pacific Rim incorporating the Australasian, 2011Co-Authors: Chunning Huang, Alexander AleksandrovAbstract:Many Laser applications in high energy physics require an enormous Average Laser Power that is several orders of magnitude higher than what is available from the present Laser technology. This paper reports the development of a macropulse mode Laser system and a Power recycling dual-wavelength optical cavity. The proposed technology has a capability of providing 50 ps/402.5 MHz/1 MW peak Power UV pulses while operating at 1 ms/60 Hz macropulse mode which is required in the Laser assisted hydrogen ion beam stripping for the Spallation Neutron Source.
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Laser optics development for the Laser assisted H− beam stripping at Spallation Neutron Source
2011 International Quantum Electronics Conference (IQEC) and Conference on Lasers and Electro-Optics (CLEO) Pacific Rim incorporating the Australasian, 2011Co-Authors: Chunning Huang, Alexander AleksandrovAbstract:Many Laser applications in high energy physics require an enormous Average Laser Power that is several orders of magnitude higher than what is available from the present Laser technology. This paper reports the development of a macropulse mode Laser system and a Power recycling dual-wavelength optical cavity. The proposed technology has a capability of providing 50 ps/402.5 MHz/1 MW peak Power UV pulses while operating at 1 ms/60 Hz macropulse mode which is required in the Laser assisted hydrogen ion beam stripping for the Spallation Neutron Source.
Hideo Tashiro - One of the best experts on this subject based on the ideXlab platform.
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5 kW transversely excited atmospheric CO2 Laser driven by a solid state exciter employing insulated gate bipolar transistors
Review of Scientific Instruments, 1993Co-Authors: Hidekazu Hatanaka, Katsumi Midorikawa, Minoru Obara, Hideo TashiroAbstract:An Average Laser output Power as high as 5 kW has been produced from a transversely excited atmospheric CO2 Laser pumped with a new solid state exciter. The exciter providing a 100 J transfer energy consisted of a high voltage pulse generator and a two stage magnetic pulse compressor. A stack of new high Power semiconductor switches, called insulated gate bipolar transistors, was employed for the main switch of the pulse generator. A sophisticated discharge head with the corona preionization behind a perforated anode was designed to realize fast and uniform gas flow in cooperation with acoustic dampers. The maximum Average Laser Power of 4.6 kW was attained at a repetition rate of 550 pps with an overall efficiency as high as 10.5%. The maximum repetition rate achieved was 1.1 kpps, at which the resulting Average Laser Power was 3.4 kW.
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Use of Insulated Gate Bipolar Transistors in an All Solid State Exciter for Multikilowatt Average-Power, TEA CO2 Lasers.
The Review of Laser Engineering, 1993Co-Authors: Hidekazu Hatanaka, Katsumi Midorikawa, Minoru Obara, Tsutomu Takahashi, Yuichiro Terashi, Shyouji Ishizaka, Hideo TashiroAbstract:Using insulated gate bipolar transistors (IGBT), we constructed an efficient, all solid state exciter for high efficiency, high Power operation of a transversely excited atmospheric (TEA) CO2 Laser. The exciter was composed of a high-voltage pulse generator and a two-stage magnetic pulse compressor. Forty-eight series and two parallel IGBTs were used as the main switch of the pulse generator. The maximum switching voltage as high as 36 kV was achieved with a transfer energy of about 100J. The pulse generator, employing an LC inversion circuit, produced a 65 kV, 7.5μs pulse, which was compressed to 0.5μs by the pulse compressor. The use of an IGBT stack decreased energy waste in a snubber circuit, resulting in a high efficiency of more than 90%. By applying the exciter to a TEA CO2 Laser with a discharge volume of 0.5l, an Average Laser Power of 4.6 kW was attained at a repetition rate of 550 pps for a switching energy of 78J. The overall efficiency of the Laser was as high as 10.5%. A repetition rate of 1.1 kpps was attained, resulting in an Average Laser Power of 3.4 kW by reducing the switching energy to 42J.
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High-repetition-rate, multijoule transversely excited atmospheric CO2 Laser
1991Co-Authors: Hidekazu Hatanaka, Katsumi Midorikawa, Hideo Tashiro, Nobuo Kawahara, Minoru ObaraAbstract:The high-repetition-rate operation of a transversely excited atmospheric CO2 Laser pumped by an all-solid- state exciter consisting of a three-stage magnetic pulse compressor has been tested. At a repetition rate of 140 pps, an Average Laser Power of 1.2 kW was obtained with an overall efficiency of 7.6%. For further increase of the repetition rate, influence of density perturbation on Laser performances (discharge stability, Laser output energy and beam quality) have also been investigated.
Minoru Obara - One of the best experts on this subject based on the ideXlab platform.
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5 kW transversely excited atmospheric CO2 Laser driven by a solid state exciter employing insulated gate bipolar transistors
Review of Scientific Instruments, 1993Co-Authors: Hidekazu Hatanaka, Katsumi Midorikawa, Minoru Obara, Hideo TashiroAbstract:An Average Laser output Power as high as 5 kW has been produced from a transversely excited atmospheric CO2 Laser pumped with a new solid state exciter. The exciter providing a 100 J transfer energy consisted of a high voltage pulse generator and a two stage magnetic pulse compressor. A stack of new high Power semiconductor switches, called insulated gate bipolar transistors, was employed for the main switch of the pulse generator. A sophisticated discharge head with the corona preionization behind a perforated anode was designed to realize fast and uniform gas flow in cooperation with acoustic dampers. The maximum Average Laser Power of 4.6 kW was attained at a repetition rate of 550 pps with an overall efficiency as high as 10.5%. The maximum repetition rate achieved was 1.1 kpps, at which the resulting Average Laser Power was 3.4 kW.
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Use of Insulated Gate Bipolar Transistors in an All Solid State Exciter for Multikilowatt Average-Power, TEA CO2 Lasers.
The Review of Laser Engineering, 1993Co-Authors: Hidekazu Hatanaka, Katsumi Midorikawa, Minoru Obara, Tsutomu Takahashi, Yuichiro Terashi, Shyouji Ishizaka, Hideo TashiroAbstract:Using insulated gate bipolar transistors (IGBT), we constructed an efficient, all solid state exciter for high efficiency, high Power operation of a transversely excited atmospheric (TEA) CO2 Laser. The exciter was composed of a high-voltage pulse generator and a two-stage magnetic pulse compressor. Forty-eight series and two parallel IGBTs were used as the main switch of the pulse generator. The maximum switching voltage as high as 36 kV was achieved with a transfer energy of about 100J. The pulse generator, employing an LC inversion circuit, produced a 65 kV, 7.5μs pulse, which was compressed to 0.5μs by the pulse compressor. The use of an IGBT stack decreased energy waste in a snubber circuit, resulting in a high efficiency of more than 90%. By applying the exciter to a TEA CO2 Laser with a discharge volume of 0.5l, an Average Laser Power of 4.6 kW was attained at a repetition rate of 550 pps for a switching energy of 78J. The overall efficiency of the Laser was as high as 10.5%. A repetition rate of 1.1 kpps was attained, resulting in an Average Laser Power of 3.4 kW by reducing the switching energy to 42J.
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High-repetition-rate, multijoule transversely excited atmospheric CO2 Laser
1991Co-Authors: Hidekazu Hatanaka, Katsumi Midorikawa, Hideo Tashiro, Nobuo Kawahara, Minoru ObaraAbstract:The high-repetition-rate operation of a transversely excited atmospheric CO2 Laser pumped by an all-solid- state exciter consisting of a three-stage magnetic pulse compressor has been tested. At a repetition rate of 140 pps, an Average Laser Power of 1.2 kW was obtained with an overall efficiency of 7.6%. For further increase of the repetition rate, influence of density perturbation on Laser performances (discharge stability, Laser output energy and beam quality) have also been investigated.
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An all solid‐state magnetic pulse compressor with amorphous metals for pumping a repetition‐rated KrF excimer Laser
Review of Scientific Instruments, 1990Co-Authors: Hiroshi Tanaka, Minoru ObaraAbstract:We have developed an all solid‐state exciter consisting of a magnetic pulse compressor with a transfer energy of 10 J/pulse approximately for KrF discharge Lasers. The magnetic pulse compressor was operated with an energy transfer efficiency of 65% at a repetition rate frequency of 40 pps. A KrF excimer Laser excited by the all solid‐state exciter was operated with an Average Laser Power of 2.7 W. Four types of amorphous metals as a magnetic core material were experimentally compared in terms of their magnetic induction and magnetic loss so as to be used in the all solid‐state exciter.
