Methods to reduce laser speckle based on orthogonal phase diffusers

联系人：仝召民副教授，电子邮件：zmtong@ mail点xjtu点edu点cn

Contact: Assoc. Professor Zhaomin Tong, Email: zmtong at mail dot xjtu dot edu dot cn

和随机相位散射屏相比，正交相位散射屏（OPD）存在激光散斑抑制效果更有效和散射激光束相对比较弱（激光率高）等优点。在硅衬底上，通过溅射铝金属层等工艺，加工出MEMS被动式微镜阵列，对激光束的相位进行快速动态调制，相位调制的幅度为0或π。人眼积分时间内，N个独立非相关散斑图片的叠加，可将激光散斑降低1/sqrt (N)。

Comparing to a random phase diffuser, an orthogonal phase diffuser (OPD) can reduce laser speckle more efficiently and scatter lights less (higher etendue). By sputtering aluminum layers on top of the silicon substrate, a MEMS passive micro mirror array has been fabricated successfully. The laser beam is modulated dynamically, where the phase modulation depth is 0 or π. During the integration time of human eye, by overlapping the created N independent speckle images, the speckle contrast can be reduced by 1/sqrt (N).


图1. 3×3 MEMS被动式微镜阵列模型，微镜被正交的电极组控制。
Fig. 1 Sketch map of a 3×3 BMMA model, which is driven by two sets of orthogonally aligned electrodes.  

  
图2. MEMS被动式微镜阵列SEM图。
Fig. 2 SEM images of the fabricated BMMA. (a) Stoppers on top of the bottom electrodes after RIE, and (b) the released mirrors.

详见专利/For details see the following patents:

1.       Z. Tong, W. Gao, X. Chen, M. Akram, G. Ouyang， and K. Wang, speckle reduction, US20110216390A1, GB2480228A and CN201110054854.4。

2.       Z. Tong(仝召民)，X. Chen(陈旭远)，W. Gao(高文宏)，and Y. Shi(石云波)，A binary phase modulator based on the MEMS micro mirror array(基于MEMS微镜阵列的二元相位调制器)， CN201210512289.6。