为了提高投影仪的成像品质,提出了一种以激光作为照明光源,对激光扩束、准直,并使用位相片调制相位,以X棱镜实现RGB光源的合束。为了解决激光散斑问题,提出了一种利用压电陶瓷结合位相片,将时间上连续的激光分成多束独立的激光脉冲,产生N个独立的散斑图像,对N个独立的激光散斑图案进行叠加,从而实现了对激光散斑的抑制,理论上实现了叠加后的散斑对比度可以降为原对比度的1/N。在20 ms内,位相片实现了30幅独立的散斑图案的叠加,通过对散斑图案的采集和分析,单幅散斑图案的对比度为0.993,叠加后散斑对比度降至0.191;结果表明散斑图案的叠加使散斑对比度得到了抑制。为后续的激光投影光路设计提供了一个参考。

In order to improve the image quality of the projector, a laser beam is used as the illumination source. The laser beam is expanded and collimated, and the phase plate is used in phase modulation. The combination of the RGB light sources is realized by the X prism. To solve the problem of laser speckle, a method of dividing the laser beam into several independent laser pulses is proposed by using the piezoelectric ceramic and the phase plate, and generating N independent speckle images. These independent laser speckle patterns are superposed so as to achieve the restraining of laser speckle. Theoretically the speckle contrast can be reduced to 1/N of the original contrast after superposition. In 20 milliseconds, the phase plate achieves the superposition of 30 independent speckle patterns. Through the speckle pattern collection and analysis it is found that a single speckle pattern contrast ratio is 0. 993, and the contrast drops to 0. 191 after the superposition. The superposition of the pattern restrains the contrast of the speckle. This provides a reference for the subsequent laser projection optical path design.