Design of diffractive optical element for beam smoothing in Fresnel diffraction region

In this paper, the precise design of the diffractive optical element (DOE) is completed for beam smoothing in Fresnel diffraction region. By using the hybrid algorithm, merging Hillclimbing with Simulated Annealing, true beam smoothing has been obtained, the intensity distribution of any point, besides the used sampling point in the optimization, on the output plane is consistent with the demand for beam smoothing. The phase depth of the designed DOE is smaller than π, which is very beneficial for the followup fabrication.