Near-field shaping with two binary diffractive optical elements in tandem

Diffractive optical elements (DOEs) are commonly used for beam shaping in the far field. In the present work, we develop an algorithm for near-field beam shaping using a double DOE system with binary modulation, so that it can be easily implemented on a glass substrate. In a first stage, the first amplitude DOE is equal to the target intensity distribution and the second phase DOE is obtained using a simple and fast iterative technique. In order to improve the optical efficiency of the system, we also analyze the behavior of the algorithm when the first DOE is not equal to the target image, but a widened version of it. Several numerical simulations are obtained, and an analysis of tolerances is performed.