液晶光调制计算全息相移器

在同轴相移数字全息实验中，相移量的准确性、稳定性对实验结果起着很重要的作用，因此相移器的研究已成为相移数字全息实验研究中的一个重要内容。在以往应用的相移器中，大多是通过机械驱动改变光程来实现相移，这种方法会使光路变得复杂。提出了一种新型的相移器——液晶光调制计算全息相移器，它将大大简化光路的设计，同时避免机械运动，实现相移量的全数字化控制。该相移器是基于计算全息原理和傅里叶变换的位移定理所提出的，它将液晶显示器(LCD)作为光学显示元件，通过适当改变显示在液晶显示器上的计算全息图的编码，使其同时实现波面变换和相移。给出了液晶光调制计算全息相移器的理论分析，并通过实验测量表明其相移量的波动范围仅在0．036 rad以内，具有很高的精确性、可重复性和稳定性，最后验证了该相移器用于同轴相移数字全息实验的可行性。

Computer-Generated Holographic Phase Shifter with Liquid Crystal Display

Exact phase shifts are very important for phase-shifting digital holography or interferometry. Some phase-shifting methods suitable for different applications have been proposed; but most of them often require precise moving or rotating drivers. A new digital phase shifter with liquid crystal display (LCD) is proposed in this paper. In this method, the phase shifts needed in digital holography are induced by changing encodes of the computer-generated holograms (CGH) displayed on the LCD. The advantage of this method is that the phase shifts can be controlled digitally and no any precise mechanical moving or rotating element is required. Both the theoretical analysis and experimental results demonstrate the feasibility of this approach. The phase stability of the LCD as a phase shifter is studied experimentally. The experiments showed that the range of the phase fluctuates is below about 0.036 rad.