Effect of projection lens numerical aperture and aberrations on speckle reduction in line-scan laser projectors

摘要

Barker and Barker-like binary phase codes have previously been used for speckle reduction in line-scan laser projectors, and a speckle contrast factor decreased down to 6% has been theoretically achieved assuming ideal imaging conditions. In this article, it is shown by theoretical simulations that the speckle reduction performance of the the binary phase codes is adversely affected by the finite numerical aperture and the aberrations of the projections lens. A minimum numerical aperture of the projection lens is needed to faithfully reproduce the binary phase code placed at an intermediate image plane onto the final display screen. The effects of the cell dimension of the binary phase code are also considerd in simulations.