Random-height microlens array zoom homogenizer for excimer laser beam shaping

Excimer laser homogenizers based on periodic microlens arrays exhibit limited tunability and cannot maintain imaging quality during zoom operation. Their performance is highly sensitive to source spatial coherence, leading to interference fringes and degraded output uniformity. To overcome these limitations, a random-height microlens array (RHMLA) zoom homogenizer is proposed for continuously variable beam shaping with high uniformity and sharp intensity edges. A ray transfer matrix based design is combined with wave optics modeling of partially coherent excimer laser propagation to maintain the imaging condition across the zoom range. The RHMLA height distribution is optimized using particle swarm optimization with a worst case objective function to ensure robustness over multiple zoom states. Simulations demonstrate that the optimized RHMLA suppresses coherence-induced intensity modulation, with edge steepness exceeding 1.14, and reduces non-uniformity to below 2.32 %. The system performance under zoom variation and defocus is analyzed, and fabrication errors are quantified using variance-based global sensitivity analysis.