动态主观散斑的时间相关性研究

Analysis of temporal coherence of dynamic subjective speckle

根据散射屏移动时动态主观散斑时间相关公式,分析了成像系统主要参数对动态主观散斑时间相关性的影响:一般情况下屏表面参数对散斑的时间相关性影响较小;激光光斑大于成像系统物面分辨斑时,散斑时间相关性由透镜孔径大小决定;激光光斑小于成像系统物面分辨斑的尺寸时,减小激光光斑尺寸能减弱散斑时间相关性。对以上结果进行了相关的理论模拟和部分实验验证,通过模拟发现,激光光斑小于成像系统物面分辨斑时,散斑时间相关长度和光斑尺寸大小成正比。结论对于激光投影系统中利用时间平均进行的散斑抑制具有指导意义。

The formula of temporal coherence of dynamic influence of optical parameters from the imaging system on subjective speckle was deduced, by which the temporal coherence of speckle was analyzed. It is concluded that the influence of the parameters of screen on speckle temporal coherence can be neglected and the speckle temporal coherence is mainly affected by the diameter of the lens or the size of laser spot on screen. If the size of laser spot is lager than that of resolution spot on object plane, the diameter of lens gives the mainly affection, while on the other side the size of laser spot gives the dominating affection and the temporal coherence can be reduced by reducing the size of laser spot on screen. The result was confirmed by simulation and experiment, and it can give an instruction to speckle reduction in laser display.