激光投影显示中新型散射体的散斑抑制

Speckle suppresion by new diffuser in laser projection display system

激光的强相干性造成了激光投影显示中出现大量干涉条纹和散斑,为了消除干涉条纹和散斑对图像质量的影响,采用旋转新型散射体(Engineered Diffuser TM)的方法在一定积分时间内获得叠加的清晰图像。首先,介绍了激光投影显示中散斑的成因及采用时间平均抑制散斑的理论依据。接着,分析了传统散射体毛玻璃和Engineered Diffuser TM在结构及功能上的区别。最后,建立了旋转新型散射体抑制散斑的激光投影显示实验装置,对比验证了旋转新型散射体抑制散斑的效果。实验结果表明:散斑对比度降低到3.08%,图像质量良好,无明显干涉条纹。该方法满足商用激光投影显示体积小、简单易行等要求。

There are many interference fringes and speckle on the screen of laser projection display system during to the strong coherent characteristic of laser. In order to eliminate the influence of interference fringes and speckle on image quality, temporally averaged patterns was obtained by rotating a new kind of diffuser called Engineered DiffuserTM. First, the reason of speckle formation and the theory of speckle suppression through temporally averaged patterns were introduced. Then the differences on structure and function between traditional diffuser ground glass and Engineered DiffuserTMwere analyzed.Finally, the speckle suppresion experiment by rotating Engineered Diffuser in laser projection display system was established. The effect of speckle suppresion was tested by comparing other speckle suppression methods. Experimental results indicate that the speckle contrast is weakened to 3.08%. The patterns quality is good and has no interference fringes. It can satisfy the laser projection display system requirements of small volume, simple practice and so on.