基于DMD消除零级光斑的计算全息显示

Computational Holographic Display Based on DMD Elimination of Zero-level Spots

在基于DMD(Digital Micromirror Devices)的计算全息系统中,全息图的零级光斑以及多级衍射对光学重建图像的质量影响很大。本文提出了改进光路系统实现对计算全息重建图质量优化的方法。该方法在G-S算法下,通过在空间光调制器后方增加一个透镜和光阑;使经过空间光调制器衍射后的光线经过傅里叶透镜会聚,再将光阑放置在透镜的后焦面上。通过左右平移光阑的位置,使其在零级光斑和多级衍射的中心,从而滤除零级光斑和多级衍射来获得更高质量的重建像。本文中的光路也节约了空间占有率。实验采用了二维字母CGH和三维茶壶图像进行验证,证明该方法在一般情况下的可行性。

In the DMD(Digital Micromirror Devices)based computational holographic system,the zero-level spot and the multi-level diffraction have great impacts on the quality of the optically reconstructed image.An improved optical path system is proposed to optimize the quality of computer-generated hologram(CGH)reconstruction images in this paper.With G-S algorithm,a lens and a diaphragm are added behind the spatial light modulator(SLM).The light reflected by the SLM is converged after passing through the Fourier lens.Diaphragm is placed on the back focal plane of the Fourier lens.By shifting the position of the diaphragm left and right,the diaphragm is placed in the center of the zero-order spot and multi-order diffraction.Consequently,high-quality reconstructed images are obtained due to the filtering out of the zero-order speckle and multi-order diffraction.The optical path in this work can also save space occupancy.Experiments are validated using 2D letter“CGH”and 3D teapot images to demonstrate the feasibility of the method in general.