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Wang G.,Science and Technology on Solid state Laser Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Stochastic Parallel Gradient Descent(SPGD) algorithm can optimize the system exhibition firsthand without using of wavefront sensor, it predigests the adaptive optic system. Based on SPGD algotithm, a model with 32 element demormable mirror was simulated, the capability of correct toward static aberration and convergence of SPGD algorithm are analysed, the relationship of gain coefficient, stochastic perturbation amplitude are discussed, an adaptive adjustment of gain coefficient is proposed, and it can improve convergence rate effectively. © 2014 SPIE.

Lian T.,Xidian University | Wang S.,Xidian University | Guo Z.,Xidian University | Li B.,Xidian University | And 3 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2012

A surface heat source adjustment approach to calculate temperature field is presented in this paper. In the approach, virtual surface heat source is introduced at the boundary of the object to solve the boundary value problem of the steady-state heat conduction equation. A contact model of rough surfaces with heat conduction connection is established. On this basis, the randomly distributed boundary conditions are established, and the temperature field in the medium is computed by using the surface heat source adjustment method. The result shows that the temperature field presents some random fluctuation due to the untight contact between the actual surfaces. The fluctuation is very obvious near the boundary while it is not obvious at the center, and the smaller the effectively contacted area, the more obvious the fluctuation is. For example, the fluctuation of 50% effective contact is more obvious than that of 75%.

Hao J.-P.,Tsinghua University | Hao J.-P.,Science and Technology on Solid state Laser Laboratory | Yan P.,Tsinghua University | Xiao Q.-R.,Tsinghua University | And 2 more authors.
Chinese Physics B | Year: 2014

With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-nm fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%. © 2014 Chinese Physical Society and IOP Publishing Ltd.

Sui X.-L.,Science and Technology on Solid state Laser Laboratory | Zhou S.-H.,Science and Technology on Solid state Laser Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The design and performance of Optical frequency modulation continuous wave (OFMCW) coherent laser radar is presented. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed.We also give a hardware structure of the OFMCW coherent laser radar. We made a detailed analysis of the measurement error. Its accuracy in the speed range is less than 0.5%.Measurement results for the movement of the carrier has also made a detailed assessment. The results show that its acceleration vector has better adaptability. The circuit structure is also given a detailed design. At the end of the article, we give the actual authentication method and experimental results. © 2013 SPIE.

Zou Y.,Science and Technology on Solid state Laser Laboratory | Bi G.,Science and Technology on Solid state Laser Laboratory | Pang Q.,Science and Technology on Solid state Laser Laboratory | Mao X.,Science and Technology on Solid state Laser Laboratory | Wang J.,Science and Technology on Solid state Laser Laboratory
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2014

Mid-infrared laser at 3-5 μm has very important application in opto-electrionic countermeasure. If the infrared laser is pico-second pulse, as it has much higher peak-power, it will be much more powerful in contermeasure filed. In this paper, tunable optical parametric generator (OPG) pumped by a 1.06 μm picosecond laser based on periodically poled stoichiometric lithium tantalate (PPSLT) was reported to get pico-second mid-infrared laser. The periodically poled Lithium niobate crystal was a single structure (29.5 μm). The pumping source was a home-made pico-second laser, which used a LD side-pumped regenerative amplifier. The maximum output power was 2.02 W at a frequency of 1 kHz, and pulse-wide was 13.6 ps. A continuous tunable middle-infrared (mid-IR) spectrum (idler wave) of 3.98-3.68 μm was obtained by changing the crystal temperature from 40°C to 200°C. When the maximum available average pump power was 2.02 W, the idler output power of OPG was 190 mW at 120°C, the optical-optical efficiency was 9.4%. This experimental research shows the possibility to get a output of picosecond mid-infrared laser by OPG at several watts level.

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