Laser patterning of glass films for the fabrication of binary silicate glass optics

The fabrication of binary phase masks by excimer laser ablation of thin borosilicate glass films deposited on fused silica substrates is reported. The 1.1 μm thick films, prepared via magnetron sputtering, exhibit high optical quality and sufficient UV absorption to enable precise structuring at 193 nm wavelength. Rear-side irradiation allows for full film removal with minimal substrate damage and near-zero debris formation, yielding clean line profiles with high edge quality. In contrast to previously used silicon suboxide layers, the borosilicate films provide high UV transmission and can be further improved by moderate thermal annealing at 500 °C. The resulting phase masks demonstrate a phase shift of ~ 3π at 405 nm, generating efficient diffraction into the ± 1st orders with measured intensities approaching theoretical expectations. The parallel nature of the mask-based ablation scheme enables scalable, high-throughput fabrication, making this approach highly attractive for applications in laser micro machining, diffractive optics, and structured illumination systems.