Beam Homogenization of a Fresnel Lens Array with a Randomly Distributed Phase for Laser Beams

To eliminate the multi-beam interference, a binary and randomly distributed phase was introduced to the Fresnel lens array and a binary phase change of 0 or is applied to individual Fresnel lens. This change in phase disrupts the phases of the periodic beams, and therefore reduces the effect of multi-beam interference on the homogenized plane. The numerical simulation of the laser beam homogenization were carried out using the Fresnel lens with an aperture of 0.5 mm and the foci of 6 mm, and the array number of 20 x 20. The simulation results show that the overall uniformity of the target plane is calculated as 90% and the beams energy efficiency can be up to 96%. The designed Fresnel lens array was fabricated using microelectronic technologies. The measured uniformity of the homogenized laser beams at a wavelength of 1 064 nm was 83%, and the beams energy efficiency was 96%. Our results indicate that the introduction of the binary and randomly distributed phase to the periodic microlens array can effectively decrease the influence of interference and improve the uniformity of homogenization of single-mode Gaussian beams.