微尺度位移、形貌测量系统及应用

研制了一套可应用于MEMS器件的微尺度测量系统,可以在受载状态下实时检测MEMS器件的面内位移、离面位移和三维形貌.该系统中,面内位移测量是一个基于白光数字散斑相关方法的显微光学测量系统,与相应的力学加载系统结合,可以得到MEMS器件在受载状态下的实时面内位移;离面位移和三维形貌测量则是一个基于相移显微投影光栅方法的光学测量系统,与相应的力学加载系统结合,可以得到MEMS器件在受载状态下的实时三维形貌和离面位移.最后给出了几个典型的MEMS器件面内位移、离面位移和三维形貌的实测结果.

障碍物扰动对预混火焰发展的影响

研究了半开口管道中障碍物对预混火焰传播的影响．结果表明，由于障碍物引起的扰动，使火焰在传播过程中不断加速，同时管内压力上升．根据火焰速度的量级，在受限管道中的火焰传播可以分为3种状态：熄火态、雍塞态和爆轰态．在贫燃极限附近，火焰加速一段距离后自动熄灭；在雍塞态，最大火焰速度略低于燃烧产物声速，基本上不受阻塞比变化的影响；随着当量比的上升，对敏感气体而言，火焰传播由爆燃转变为爆轰，最大火焰速度随阻塞比的增加而降低；而对于非敏感气体，则不存在爆燃转爆轰现象．管内压力随障碍物阻塞比的变化并不呈现单调规律．同时用非稳态可压缩流体模型模拟了管内的火焰加速和压力发展过程，计算结果和实验结果吻合得较好．

海面微波散射与风生波短波谱

海面微波散射反演是星载微波器遥感海面风场技术的一个关键组成部分。考虑到目前海面微波散射反演工程模型的纯经验性和依赖散射计工作频率等局限，以及以双尺度理论为代表的物理模型中对短波谱该画存在的明显不足，本文致力于建造一个既有理论基础又具实际应用可行性的微波散射模型。根据在风水槽实验中获取的风生短波频谱实测数据以及现有不同波段的实际微波散射资料的分析，文中提出了一个适于散射反演的风生波短波谱形式，进而建立起一个可实际应用的海面微波散射模型。基于本文提出的微波散射模型，从五个不同波段的微波散射系数对风速进行了反演，并与其它模型的计算结果以及实测数据进行了比较。结果表明：本文散射模型克服了以往工程模型只适用单一波段的局限性，可在相当宽微波频率范围(0.428～34.4GHz)有很好的应用，同时计及了散射系数迎顺风不对称性的特点，与散射实测数据的符合程度是令人满意的。此外，作为一个应用，还给出了将本文散射模型应用于估算海面气体传输速率的计算实例，同样获得与实验测量数据良好的符合。

外加高压电场下空气中激光等离子体通道寿命研究

通过对飞秒激光在空气中产生的等离子体通道两端外加高压,来研究通道的寿命变化情况。实验得到,当在等离子体通道两端外加高压时(350 kV/m),等离子体通道寿命延长了近3倍。理论模拟和分析结果表明在外加电场条件下,碰撞电离得到增强,吸附作用相对减弱,解离复合系数随着电子平均能量的增加而下降的趋势更为剧烈,这进一步引起了等离子体通道寿命的延长。实验结果与理论分析共同表明了利用外加电场对空气中激光等离子体通道寿命进行延长的可行性。

Effect of microcosmic optical parameters of dopants on the signal-to-noise ratio in doubly doped LiNbO3 crystals

We propose a united theory that describes the two-center recording system by taking scattering noise into account. The temporal evolution of the signal-to-noise ratio in doubly doped photorefractive crystals is described based on jointly solving material equations and coupled-wave equations with the fourth-order Runge-Kutta method. Roles of microcosmic optical parameters of dopants on the signal-to-noise ratio are discussed in detail. The theoretical results can confirm and predict experimental results. (c) 2005 Elsevier GmbH. All rights reserved.

Discussions about FFT-based two-step phase-shifting algorithm

An FFT-based two-step phase-shifting (TPS) algorithm is described in detail and implemented by use of experimental interferograms. This algorithm has been proposed to solve the TPS problem with random phase shift except pi. By comparison with the visibility-function-based TPS algorithm, it proves that the FFT-based algorithm has obvious advantages in phase extracting. Meanwhile, we present a pi-phase-shift supplement to the TPS algorithm, which combines the two interferograms and demodulates the phase map by locating the extrema of the combined fringes after removing the respective backgrounds. So combining this method and FFT-based one, one could really implement the TPS with random phase shift. Whereafter, we systematically compare the TPS with single-interferogram analysis algorithm and conventional three-step phase-shifting one. The results demonstrate that the FFT-based TPS algorithm has a satisfactory accuracy. At last, based on the polarizing interferometry, a schematic setup of two-channel TPS interferometer with random phase shift is suggested to implement the simultaneous collection of interferograms. (c) 2007 Elsevier GrnbH. All rights reserved.

977nm抽运下掺铒碲酸盐基氧卤玻璃的光谱特性

研究了掺铒TeO2-ZnO-PbCl2碲酸盐基氧卤玻璃在977nm激光二极管抽运下的发光和上转换发光特性，结果发现除红外1．53μm^4I13.2→^4I15/2发光外(荧光半高宽高达69nm)，该玻璃还存在很强的^2H11/2→^4I15/2(527nm)，^4S3/2→^4I15/2(549nm)和^4R9/2→^4I15/2(666nm)可见上转换发光．应用Judd-Ofelt理论计算得到玻璃强度参数Ω1(t=2，4，6)分别为Ω2=5．87×10^20cm^2,Ω4=2．08×10^2-cm^2，

The effects of oxygen partial pressure on the optical absorption edge and the UV emission energy of ZnO films

The optical absorption edge and ultraviolet (UV) emission energy of ZnO films deposited by direct current (DC) reactive magnetron sputtering at room temperature have been investigated. With the oxygen ratio increasing, the structure of films changes from zinc and zinc oxide coexisting phase to single-phase ZnO and finally to the highly (002) orientation. Both the grain size and the stress of ZnO film vary with the oxygen partial pressure. Upon increasing the oxygen partial pressure in the growing ambient, the visible emission in the room-temperature photoluminescence spectra was suppressed without sacrificing the band-edge emission intensity in the ultraviolet region. The peaks of photoluminescence spectra were located at 3.06---3.15 eV. From optical transmittance spectra of ZnO films, the optical band gap edge was observed to shift towards shorter wavelength with the increase of oxygen partial pressure.