Liang Jinyang, Wu Sih-Ying, Fatemi Fredrik K, Becker Michael F
Electrical and Computer Engineering Department, University of Texas at Austin, Austin, Texas 78712, USA.
Appl Opt. 2012 Jun 1;51(16):3294-304. doi: 10.1364/AO.51.003294.
Phase compression is used to suppress the on-axis zero-order diffracted (ZOD) beam from a pixelated phase-only spatial light modulator (SLM) by a simple modification to the computer generated hologram (CGH) loaded onto the SLM. After CGH design, the phase of each SLM element is identically compressed by multiplying by a constant scale factor and rotated on the complex unit-circle to produce a cancellation beam that destructively interferes with the ZOD beam. Experiments achieved a factor of 3 reduction of the ZOD beam using two different liquid-crystal SLMs. Numerical simulation analyzed the reconstructed image quality and diffraction efficiency versus degree of phase compression and showed that phase compression resulted in little image degradation or power loss.
相位压缩用于通过对加载到像素化纯相位空间光调制器（SLM）上的计算机生成全息图（CGH）进行简单修改，来抑制来自该调制器的轴上零阶衍射（ZOD）光束。在CGH设计之后，通过乘以一个恒定比例因子对每个SLM元件的相位进行同等压缩，并在复单位圆上旋转，以产生与ZOD光束相消干涉的抵消光束。实验使用两种不同的液晶SLM实现了ZOD光束强度降低3倍。数值模拟分析了重建图像质量和衍射效率与相位压缩程度的关系，结果表明相位压缩导致的图像退化和功率损失很小。
