A beam shaping and collimation technique using freeform optics optimized by NSGA-II

Abstract

This study presents a technique to address the inherent asymmetry of laser diode emission. We propose a freeform surface system to convert the diode’s elliptical Gaussian output into a flat-top intensity profile at a specified working distance. The profiles of the freeform surfaces are determined using a three-dimensional, point-by-point iterative method. Beam uniformity and collimation of the system depend strongly on the iteration’s starting position. To optimize this parameter, we employ a Non-dominated Sorting Genetic Algorithm II to determine the optimal configurations. We demonstrate the feasibility of this approach with three design examples of circular and rectangular flat top beams. In all cases, the RMS non-uniformity on the target plane almost remains below 0.2 at distance up to 1000 mm. The resulting beam shaping system is not only flexible and compact but also features achromatic and multi-wavelength capabilities, making it suitable for applications demanding precise light control.