Optimal speckle suppression in laser projectors using a single two-dimensional Barker code diffractive optical element

Abstract

An effective method of speckle suppression using one 2D diffractive optical element (DOE) moving with constant velocity based on the periodic Barker code sequence is developed. We prove that this method has the same optical parameters as the method based on two 1D Barker code DOEs stretched and moving in orthogonal directions. We also show that DOE movement in a special direction allows the full numerical aperture of the objective lens to be used for speckle averaging by angle diversity. It is found that the 2D DOE based on a Barker code of length of 13 allows the speckle contrast to be decreased below the sensitivity of the human eye with optical losses of less than 10%.