Laser Based Rapid Fabrication of SiO2-phase Masks for Efficient UV-laser Micromachining

The laser based fabrication of surface relief SiO2 phase masks is demonstrated: First, a UV-absorbing coating of silicon monoxide (SiO, thickness 150-300 nm) is deposited on a fused silica substrate. Second, the SiO-coating is patterned by excimer laser ablation (248 nm or 193 nm) at fluences of 0.2 to 0.5 J/cm(2) to form the desired phase structure. Third, the SiO-material is oxidized to UV-transparent silicon dioxide (SiO2). Applications of these phase masks in combination with suitable imaging optics for efficient laser micro machining are demonstrated.