研究了用LED作为光栅光调制器的照明光源时,三基色光源数目之比和光源相干性对显示质量及颜色复现能力的影响。利用部分相干光和色度学的相关理论,比较了不同光源带宽对显示对比度和色彩显示的影响。结果表明光源带宽越小,显示对比度越高,色品图中的色三角的面积越大;此外,研究还发现三基色光源数目之比对色彩显示影响较大,当红绿蓝三色光源数目之比为2:1:1时,混色白场在色品图中的坐标与标准光源的白场坐标位置接近,并进一步得到在该比例下光源带宽和一般显色指数的关系:光源的一般显色指数随着光源带宽的减小而减小。从而为光学系统的设计提供了一个光源选择的优化方案。The influence of display quality and ability of color discrimination on different ratio of RGB light source number and different coherence of light source is analyzed,when LED is used as the lighting source for grating light modulator. By using partially coherent light and colorimetry theory,the display contrast and color display on different bandwidth is compared. The result illuminates the contrast and the area of color triangle is increasing as the bandwidth is becoming narrower,and the ratio of RGB light source number affects the quality of color display largely. The coordinate of white field is highly closed to the position of standard white light source,when the ratio of RGB light source number is 2:1:1. Meanwhile the relation between general color rendering index and bandwidth is acquired in this situation. It shows that the general color rendering index becomes less as the bandwidth is narrower. Above all,an optimized project based on the choice of light source for the design of optical system is proposed.<英文摘要>

光学信息处理是投影系统设计的关键环节,利用部分相干光理论分析了具有一定光斑尺寸的激光照明下滤波面上的光学特性并进行了数值仿真。结果表明,滤波面上的衍射光强分布是调制器透过率函数傅里叶变换模的平方与激光光斑尺寸在滤波面上几何投影间的卷积;滤波面上各衍射级次出现了展宽,并产生了混叠;各级次混叠的程度随滤波面与调制器间距的增大而减弱。搭建了相关实验系统观察到了滤波面上的衍射图样,实验结果和理论分析一致。最后提出了在光栅光调制器与滤波面间设置一个会聚透镜来减小系统光学尺寸,提高系统信息处理效果的方法,并通过实验得到了最优方案,为研究光栅光调制器的微型化投影系统提供了理论基础与实验指导。

讨论了二维光栅光调制器阵列的表面弯曲度对衍射光学特性的影响。利用实测的表面结构数据建立了阵列模型, 利用Matlab软件计算了不同弯曲度对频谱面上衍射光强的分布影响, 得到了弯曲度与对比度之间的关系。结果表明暗态时光栅面的弯曲度对成像对比度的影响很大, 如果将光栅面的中心弯曲度控制在0.1λ以内, 在像面上将获得1000以上的对比度。并通过实验动态显示器件的明暗态调制, 得出减少光栅面弯曲度的优化方案。

A novel grating light modulator for projection display is introduced. It consists of an upper moveable grating, a bottom mirror, and four supporting posts between them. The moveable grating and the bottom mirror compose a phase grating whose phase difference is controlled by the actuating voltage. When the phase difference is 2k\pi, the grating light modulator will switch the incident light to zero-order diffraction; when the phase difference is (2k-1)\pi, the grating light modulator will diffract light to first-order diffraction. A 16\times16 modulator array is fabricated by the surface micromachining technology. The device works well when it is actuated by a voltage with 1-kHz frequency and 10-V amplitude. The fabricated grating light modulator can show blackness and brightness when controlled by the voltage. This modulator has potential applications in projection display system.

针对一种新型的光调制器——光栅光调制器, 研究用LED作为其照明光源时对光学调制特性的影响。以部分相干光理论为依据, 结合MATLAB仿真, 推导出用LED照明光栅光调制器时, 光源带宽对成像对比度具有较大的影响, 通过滤色片将光源带宽减小到13 nm时, 像面上的对比度约为150, 进一步减小带宽至10 nm, 对比度将达到225。光源的尺寸在与光源到光栅光调制器之间的距离相比小于0.03时, 对光栅光调制器的光学信息处理不会有影响, 并通过实验加以证实, 从而说明采用LED作为光栅光调制器照明光源的可行性。

基于标量衍射理论分析了二维光栅光调制器的衍射特性,提出了投影系统的光学处理方法,利用Matlab软件进行了仿真分析。分析结果表明,二维光栅光调制器的衍射光强分布是单个像素衍射光强的干涉叠加,其分布趋势与单个光调制器的衍射光强分布类似;通过反傅里叶变换可将各个调制器的衍射光重新分开而成像。如果用±1级衍射光的成像,相位为2kπ的调制器在投影面得到一个明亮的像,而相位为(2k-1)π的调制器在投影像面上得到一个黑暗的像。通过一个基于静态微光电系统光栅光调制器的投影光学系统得到了一幅明暗调制的像,证明了光栅光调制器用于投影显示的可行性。

提出了一种反射镜平动式光栅光调制器，每个像素主要由一个可动反射镜和上面的固定光栅组成，通过控制可动反射镜和固定光栅的距离达到对入射光的调制．依据标量衍射理论对反射镜平动式光栅光调制器工作状态的光学特性进行了详细的理论分析；并仿真了光调制器的结构参量对衍射效率和对比度的影响．发现：当可动平板和光栅的距离为λ₀和5λ₀／4，像素表现为暗态和亮态；这种光调制器的工作原理决定了其有效面积大，具有形成面阵的潜力；固定光栅占空比为1／2时，对比度最优；同时给出了对比度随入射光带宽的关系，即带宽越大，对比度急剧下降．

A micro-electro-mechanical system (MEMS) silicon-based non-silicon mirror for a 2D optical switch is designed, fabricated and measured. The result shows that the mirror has good reflective performance. And driven by static electricity, it can rotate more than 10°at voltage less than 15 V. This kind of novel mirror will have good potential applications for MEMS optical switches.