Theoretical study and design of a splitting-recombining style homogenizer

For a flat-top laser beam with low low divergence, new scheme based on splitting, inverting, and recombining has been developed. The previous system developed in MicroLas for multimode Excimer lasers, however, cannot apply to a Gaussian beam. By adding functions of path compensation and adjustable beam overlapping, a new splitting-recombining style homogenizer can convert a Gaussian beam to a flat-top beam. Since this scheme is sensitive to accuracy of separation, ratio of beam splitting, and timing of recombination, input laser beam should be collimated to large size and a beam splitter with dielectric coating should be fabricated with high accuracy. We design and study theoretically the new splitting-recombining style homogenizer for a Gaussian laser beam, including the tolerance caused by misalignment or coating quality, the beam quality depending on the beam overlapping ratio, and the effects of longitudinal pulse profile and time delay between transmitted and re-combined beam.