Design and evaluation of a diffractive beam splitter for dual-wavelength laser processing

We report a novel diffractive beam splitter designed for use in parallel laser processing with two different wavelengths. This element generates two beam arrays of the two wavelengths and enables their overlap at the process points on a workpiece. To design the deep surface-relief profile of a splitter using a simulated annealing method, we introduce a heuristic but practical scheme to determine the maximum height and the number of quantization levels. The designed corrugations were formed in photoresist by maskless grayscale exposure using a high-resolution spatial light modulator. We evaluated the optical properties of the resist splitter, thereby validating the proposed beam delivery concept.