Beam Shaping of VCSEL Arrays Using Randomized Microlens Arrays With Integrated Collimation

In active 3D imaging systems, the circular, Gaussian-shaped output of VCSEL arrays must be converted into rectangular patterns aligned with the camera's field of view. To maximize energy efficiency, the beam edges must be sharply confined to avoid illumination outside the target area. For this purpose, this work presents the design, fabrication, and experimental evaluation of randomized microlens arrays (RMLAs) and the novel collimating RMLAs (cRMLAs), which are tailored specifically to the emission characteristics of VCSEL arrays. The freeform optical elements were fabricated using grayscale two-photon polymerization and verified using confocal microscopy. Far-field beam profiles were recorded with a cost-efficient, camera-based setup and analyzed with respect to efficiency, field-of-view coverage, and intensity distribution. The results show that the cRMLAs offer a significant increase in beam shaping efficiency and spatial resolution. This represents the first monolithic randomized microlens array with integrated collimation. The approach enables compact and energy-efficient beam shaping in future active sensing systems.