基于微机电系统光栅平动式光调制器实验和优化设计

基于微机电系统(MEMS)的光栅平动式光调制器(光栅平动式光调制器)调制性能的实验研究关系到其进一步应用。设计了光栅平动式光调制器的相干光学信息处理系统实验方案,He-Ne激光器出射的光束经扩束器和准直透射后成为平行光入射光栅平动式光调制器,被测光栅平动式光调制器放置在相干光学信息处理系统的输入面,滤波器在频谱面上,显微镜放大像面上的信号,经CCD在计算机上记录存储;实验结果和理论分析吻合。对光栅平动式光调制器进行方案优化,将可动光栅边框和悬臂梁表面处理成不反光,使可动光栅和下反射镜构成的整个反射面为光栅周期的整数倍。经理论计算,在光栅周期为8μm,光栅占空比为0.5,光栅边距为2μm,周期数为6的条件下,光栅平动式光调制器图像填充率为74.67%,光学效率为81.06%,衬比度大于5000∶1。

Experiments and Structural Optimization of Micro-Electro-Mechanical System-Based Grating Moving Light Modulator

The experimental research for micro-electro-mechanical system (MEMS)-based grating moving light modulator (GMLM) is important for its further applications. Interference optical signal processing system with GMLM module was carried on, with He-Ne laser as light source, filter placed on the frequency spectrum plane, and microscope and CCD placed on the imaging plane and used for magnifying and recording imaging. The laser beam from He-Ne laser was incident on the GMLM as parallel light after passing a beam expander and a collimating lens, the GMLM is placed on the input plane of the interference optical signal processing system and the result is consistent to theoretical result. The optimization of GMLM model was achieved, the grating frame and cantilevers are processed as non-reflective, and as a result the total reflective surface composed of the movable grating and the nether mirror is integer multiple of grating period. The optimized model was theoretically analyzed in details by scalar diffraction theory, with optical efficiency of 81.06%, filling factor of 74.67% and contrast ratio higher than 5000∶1 in the condition of grating period of 8 μm, duty ratio of 0.5,grating frame of 2 μm, and period number of 6.