SPECKLE REDUCING DEVICE FOR LASER PROJECTION SYSTEM AND SPECKLE REDUCING METHOD USING THE SAME

摘要

A speckle reducing device for a laser projection system (1) and a speckle reducing method using the same are disclosed. The laser projection system (1) comprises at least a laser light source (11) for emitting laser light (110), and at least an image generation element (13), such as a light deflector as a MEMS mirror or a two dimensional intensity modulating array as a digital light processor (DLP), for modulating the laser light (110) into image light (112). The image light (112) is projected onto a screen (20) through at least a light outlet (14) to form an image. The speckle reducing device (3) utilizes at least a laser phase disturbing element (30) disposed at a projection path of the laser light between the laser light source (11) and the screen (20) for the laser light passing in a reflective or transmitting mode. At least a phase disturbing pattern (31) is arranged on a surface of the phase disturbing element (30) in order to generate uneven phase change in the laser light passing through the phase disturbing pattern (31), so that at last the coherence length of the image light emitted from the screen (20) is reduced to effectively reduce speckle.