Diffractive optical array element for realizing uniform spot on the plane non-perpendicular to the optical axis with geometrical shape transform

In this paper, the problem of transforming laser input of any shape to uniform spots output of any shape on the plane non-perpendicular to the optical axis is studied. A diffractive optical elements (DOE) array is used to obtain such uniform spot. A linear phase-shift is added to the squared cells of the DOE array so as to change the relative position and the overlapped area of every sub-focal spot to realize the geometrical shape transform. An indirect design principle based on long focal depth is adopted, which modifies the phase distribution of the cells to realize the uniform spots on three planes at right angles with the optical axis and a uniform spot is ensured on the inclined plane. A type of hybrid algorithm based on hill-climbing and simulated annealing is utilized for phase design. Simulated results show that the method is easy and valid.