Design of diffractive beam-shaping elements for non-uniform illumination waves

A method for the design of diffractive beam-shaping elements is presented which extends the finite-element-meshes (FEM) method proposed by Dresel et al. [1]. In particular, the modified method can be applied to non-uniform intensity distributions in the input and output planes. This extension is of practical significance due to the nonuniformity of real laser beam intensity distributions. The method is shown to result in so-called smooth phase functions which are desired for beam-shaping applications to overcome the well-known speckle problem. Transmission functions of diffractive phase-only elements have been computed solving beam-shaping problems of practical relevance. We have demonstrated by numerical simulation experiments that the computed elements perform the desired beam-shaping operations in good approximation.