Analysis of speckle-reduction performance in a laser rear-projection display using a small moving diffuser

— Recently, a practical method of speckle reduction in laser rear‐projection displays that uses an optical system with a small moving diffuser has attracted much attention. In this paper, a model of the speckle generation and reduction mechanism in the system is presented. Speckle in the system was investigated, focusing on the physical aspects of its generation rather than treating it statistically, and it was found that the granularity of the speckle patterns generated by the small diffuser corresponded to the size of the coherent regions on the projection screen. This determined the efficiency of the speckle reduction when the small diffuser was rotated. By using these results, a method to estimate the performance of speckle reduction on the system was developed.