激光投影显示屏表面粗糙度的测量

Surface Roughness Measurement of Screen for Laser Projection Display

显示屏是激光投影显示系统的一部分,其表面粗糙度直接影响着基于角度多样性的激光散斑抑制效果。在角度多样性散斑抑制原理的基础上,建立了被测显示屏表面粗糙度与散斑图样之间的相关性之间的联系。对显示屏表面粗糙度对照射角度和角度变化的敏感程度权衡,实验中将入射角和角度变化量分别固定在1°和0.0038°。为避免外界微扰和测试屏表面不平度对测试结果的影响,通过对被测显示屏5cm×5cm测试区域中选择9个子区域的测试结果进行平均,有效提高了测试精度。运用提出的方法确定4种材质显示屏的表面粗糙度分别为235.80,209.57,132.24和137.60μm,为设计有效降低激光散斑的投影显示屏提供了参考。

Display screen is an integral part of laser projection system. The surface roughness of screen directly affects speckle suppression based on angle diversity. The relation between speckle correlation and the surface roughness of measured screen is established by analyzing the speckle suppression method based on angle diversity. In the experiment, the incident angle is fixed to 1° and the angle increment is set to 0.0038°, which is a compromise between the sensitivities of surface roughness of the measured screen to those two factors. To avoid the effects of external perturbation and surface flatness on measured results, nine sub-regions are chosen in 5 cm×5 cm measured screen areas and measured results from these sub-regions are averaged, which effectively improves the measurement accuracy. The surface roughness for four screens determined by the proposed method are 235.80, 209.57, 132.24 and 137.60 μm, respectively, which provides a basis to design a projection display screen applied to effectively reduce laser speckle.