基于电控液晶散射片的数字全息散斑去噪研究  

Speckle denoising based on electric control the liquid crystal scattering in digital holography

作　　者：李欢 孔勇[1] 丁伟 吴虎 王振伟 LI Huan;KONG Yong;DING Wei;WU Hu;WANG Zhenwei(Control Engineer,School of Electronic and Electrical Engineering,Shanghai University of Engineering Science,Shanghai 201620,China)

机构地区：[1]上海工程技术大学电子电气工程学院控制工程系,上海201620

出　　处：《光学技术》2021年第4期398-403,共6页Optical Technique

基　　金：上海市自然科学基金(19ZR1421700)。

摘　　要：数字全息中的散斑噪声对图像质量有很大的影响,而形成散斑噪声的原因之一是参考光和物光的相干度太高,对记录的全息图引入了不必要的噪声。文章研究了利用电控液晶散射片对相干光进行退相干的操作来实现散斑去噪;通过调整电压改变物光路中电控液晶散射片的散射效果,记录得到液晶散射片在多种散射效果下照射的全息图,多种散射效果下重建物体图像的等效外观指数各有不同,将各个重建图像对比得到最优结果;在最优散射效果下将全息图叠加进行重建,重建图像中的散斑噪声得到很好的抑制且比单副效果更好。通过理论分析和实验验证证实了所提出的方法对提高数字全息系统的成像质量有很大的应用价值。Speckle noise in digital holography has a great influence on image quality, and one of the reasons for the formation of speckle noise is that the coherence between reference light and object light is too high, which leads to speckle effect and introduces unnecessary noise to recorded hologram. Speckle denoising is realized by using electrically controlled liquid crystal scatterers to decolorize coherent light. By adjusting the voltage to change the scattering effect of the electrically controlled liquid crystal scatterer in the object light path, the holograms irradiated by the liquid crystal scatterer under various scattering effects are recorded, and the equivalent appearance index of the reconstructed object image under various scattering effects is different, and the optimal result is obtained through comparative analysis. Then the hologram is reconstructed by superimposing the hologram under the optimal scattering effect and the effect is better than that of the single image. Through theoretical analysis and experimental verification, it is proved that the proposed method has great application value to improve the imaging quality of digital holographic system.

关 键 词：数字全息 散斑噪声 电控液晶散射片 低相干光 

分 类 号：O438.1[机械工程—光学工程]