New Monolithic Gaussian-to-Tophat Converter with integrated Fourier Function and Gaussian-to-Tophat Beam Splitter

摘要

Optical Gaussian-to-tophat converters (g2T) that convert a Gaussian intensity distribution into a tophat profile find growing applications in different laser processing technologies. Usually, such refractive or diffractive g2T converters comprise of two or more optical components. For example, one aspherical component to form a tophat angular distribution followed by a Fourier lens that transforms it into the desired tophat intensity distribution in the focal plane.Here we report an optical design, which combines both optical functions in a single monolithic component. The component is designed and manufactured by LIMO as a free-form profile, providing the square tophat of 100-μm width at the distance of 125 mm. Compared to the traditional g2T-converters it is much more compact, easy to adjust, and less sensitive to alignment errors.In many industrial applications, not a single but multiple tophat foci are desirable for a fast parallel processing. For such applications we have developed a Gaussian-to-Tophat beam splitter. The beam splitting is done by a refractive-diffractive high-order grating with a smooth continuous pitch profile. Thanks to the smooth profile, such a Gaussian-to-Tophat beam splitter demonstrates very high efficiency of above 95% and high homogeneity between the diffraction orders.