大功率固体激光器冷却技术进展

本文针对固体激光器散热问题,介绍了近年来国内外的先进冷却技术及其研究进展,并指出了存在的问题,为大功率固体激光器的新型高效冷却与热控技术研发提供了参考依据.     

非晶态As_2S_8半导体薄膜的光激励现象的研究及应用

实验研究了非晶态As2S8半导体薄膜在紫外汞灯和He_Cd激光照射下的光诱导现象,证实了光照射后的As2S8薄膜的折射率增大,体积缩小,可见光吸收谱的吸收带蓝移。在此基础上,应用光折变效应试制了As2S8条波导,观测到As2S8条波导的光阻断效应,实现了光_光效应的开关功能。     

临汾市广电综合业务网方案设计

1 前言 近年来,随着科学的进步和社会的发展,人类已经步入信息时代,我国广播电视网络的建设正朝着既定方向迅速推进。国家广播电视网由省级干线网及在此基础上联网的部级干线网、地区网和本地网组成。传输手段上以光缆为主、数字微波为辅。网络功能上,在保证其“喉舌”性质和“公益性”原则的基础上,充分开发网络资源,提供面向各种用户的互联互通综合业务。     

基于一维FFT频谱估计的移动物体速度估计法

提出了时间空间频率混合领域中基于一维FFT频谱估计的移动物体速度估计方法。结合移动物体的抽出,把具有两个移动物体的序列图像分离为分别包含一个移动物体的两个序列图像,当再次进行速度估计时会大大减少背景及噪声对速度估计结果的影响,可提高速度估计的精度。     

Low-light image enhancement based on Retinex theory and dual-tree complex wavelet transform

In order to enhance the contrast of low-light images and reduce noise in them, we propose an image enhancement method based on Retinex theory and dual-tree complex wavelet transform (DT-CWT). The method first converts an image from the RGB color space to the HSV color space and decomposes the V-channel by dual-tree complex wavelet transform. Next, an improved local adaptive tone mapping method is applied to process the low frequency components of the image, and a soft threshold denoising algorithm is used to denoise the high frequency components of the image. Then, the V-channel is rebuilt and the contrast is adjusted using white balance method. Finally, the processed image is converted back into the RGB color space as the enhanced result. Experimental results show that the proposed method can effectively improve the performance in terms of contrast enhancement, noise reduction and color reproduction.     

Numerical Simulation of the Non-Fourier Heat Conduction in a Solid-State Laser Medium

A hyperbolic model of non-Fourier heat conduction with non-uniform heat source is used to simulate the transient heat transfer in a high-pulse-pumped solid-state laser medium. The temperature fields are numerically analysed using the finite difference method combined with the TDMA algorithm for different pump power densities, pulse durations, thermal relaxation time and cooling intensities, respectively. The calculated results are compared with those predicted by the parabolic heat conduction model based on the Fourier law. The results indicate that the non-Fourier heat conduction phenomenon in laser media should be considered when the pump power density exceeds 104 W/m^2 or under low pulse duration. In addition, the conditions of non-Fourier effects and their influencing factors are analysed.     

超急速爆发沸腾传热的实验与理论研究

超急速爆发沸腾研究具有重大理论与实用价值。本文在实验研究的基础上,建立了脉冲激光作用下超急速爆发沸腾传热数学模型,并采用恰当的数值处理方法进行了数值模拟计算。结果表明,计算与实验结果基本吻合,在超急速爆发沸腾过程中,汽相、液相的升温吸热以及汽化潜热等是影响温度变化的重要因素,实际过程中应综合加以考虑。     

As_2S_8非晶态薄膜波导光学截止效应研究

报告了As_2S_8非晶态薄膜波导的光学截止（optical-stopping）效应的实验过程、初步结果和机理分析.介绍了硫系非晶态As2S8薄膜波导的制备工艺,以及实验光路和光学截止现象的过程.在实验基础上,结合有关硫系非晶态半导体中的其他一些光诱起现象的报道,我们提出了以微结构变动为前提、结合半导体能级理论的电子泵浦模型,解释了实验现象.     

As_2S_8薄膜光致折射率效应及其在条波导制备中的应用研究

分别采用紫外光和He—Cd激光辐照,实验研究了As2S8非晶态薄膜的光致折射率变化以及膜厚变 化的现象,归纳了实验规律,初步分析了机理。利用光诱起折射率变化效应试制了As2S8玻璃条波导,实现了良好 的导波特性。