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。

Analysis of the optical characteristic on the filtering plane of the projection system based on grating light modulators (GLM) illuminated by extended light source is the key section of the optical information processing. The optical characteristic on the filtering plane of the projection system illuminated by a laser facular of certain size is analyzed using the theory of partially coherent light and the numerical simulation. The result shows that the diffraction light intensity distribution on the filtering plane is the convolution of the squared Fourier transform of the modulator′s transmittance function and the geometric projection of the laser facular size on the filtering plane. The diffraction order extends on the filtering plane,and the aliasing phenomenon appears that through the distance between the filtering plane and the modulator increasing while the degree of aliasing decreases. The relevant experimental system is constructed and the diffraction pattern on the filtering plane is obtained. The experimental results accord with the theoretical analysis. In the end,we propose that a converging lens set between the modulator and the filtering plane could reduce the optical dimension of the system,and a method for improving the effect of system information processing.