High speckle reduction rate in a laser projection system

In this paper, we demonstrate a design for a laser picoprojector with a high rate of reduction in the speckle contrast value. The method utilizes a holographic diffuser, deformable mirror, and fast electrically tunable (FET) lens. Then we compare the reduction rate of the speckle contrast value for holographic diffusers with different divergence angles and an FET lens with different optical power ranges combined with a deformable mirror. The increase in reduction rate of speckle contrast value means that the minimum value of the speckle can be reached faster. There reduction rate increases from 4.76 to 5.74 for the 5 × 5 holographic diffuser, 3.45 to 5.66 for the 10 × 10 holographic diffuser, and 1.52 to 4.58 for the 30 × 30 holographic diffuser.