Jia Wei, Chen Zhongyu, Wen Fung Jacky, Zhou Changhe, Chow Yuk Tak, Chung Po Sheun
Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong, China.
Appl Opt. 2011 Dec 1;50(34):H10-5. doi: 10.1364/AO.50.000H10.
We describe a simple technique for coaxial holographic image recording and reconstruction, employing a spatial light modulator (SLM) modified in pure phase mode. In the image encoding system, both the reference beam in the outside part and the signal beam in the inside part are displayed by an SLM based on the twisted nematic LCD. For a binary image, the part with amplitude of "1" is modulated with random phase, while the part with amplitude of "0" is modulated with constant phase. After blocking the dc component of the spatial frequencies, a Fourier transform (FT) hologram is recorded with a uniform intensity distribution. The amplitude image is reconstructed by illuminating the reference beam onto the hologram, which is much simpler than existing phase modulated FT holography techniques. The technique of coaxial holographic image encoding and recovering with pure phase modulation is demonstrated theoretically and experimentally in this paper. As the holograms are recorded without the high-intensity dc component, the storage density with volume medium may be increased with the increase of dynamic range. Such a simple modulation method will have potential applications in areas such as holographic encryption and high-density disk storage systems.
我们描述了一种用于同轴全息图像记录和重建的简单技术，该技术采用了在纯相位模式下进行修改的空间光调制器（SLM）。在图像编码系统中，外部的参考光束和内部的信号光束均由基于扭曲向列液晶显示器的空间光调制器显示。对于二值图像，幅度为“1”的部分用随机相位调制，而幅度为“0”的部分用恒定相位调制。在阻挡空间频率的直流分量之后，用均匀强度分布记录傅里叶变换（FT）全息图。通过将参考光束照射到全息图上来重建幅度图像，这比现有的相位调制傅里叶变换全息技术要简单得多。本文从理论和实验上证明了纯相位调制的同轴全息图像编码和恢复技术。由于全息图记录时没有高强度直流分量，随着动态范围的增加，体积介质的存储密度可能会提高。这种简单的调制方法将在全息加密和高密度磁盘存储系统等领域具有潜在应用。
