| Ultrahigh resolution projectors create images with more than twenty million pixels, an order of magnitude more than current display technologies. To achieve this level of resolution, the Evans & Sutherland Laser Projector (ESLP) utilizes one dimensional Grating Light Valve (GLV) modulators, which require laser light sources. The lasers that enable such ultrahigh resolution also cause speckle, which is visible as a grainy pattern superimposed on the image. The ESLP has solved many technological challenges and will revolutionize high resolution projection displays, but the problem of speckle must be solved for GLV laser projectors to become commercially viable.; This paper identifies the difficulties with current speckle reduction approaches as applied to ultrahigh resolution GLV laser projectors, including the introduction of objectionable image artifacts. A moving phase grating placed at an intermediate image plane is shown to have the most potential for speckle reduction. Mathematical models are introduced to predict the appearance of the image artifacts and to predict the speckle reduction achieved through implementation of the phase grating. Experimental results are presented that show the predicted speckle reduction is achieved. |
