Published online by Cambridge University Press: 10 February 2011
The F2laser is a promising source for direct etching of microstructures and the precise shaping of optical-grade surfaces on wide bandgap materials such as fused silica. We report here on residual tensile stresses induced in fused silica (Coming 7940, UV grade) by 157-nm laser ablation. Plastic strain of 160-mm thick rectangular strips, monitored with an optical interferometric microscope, revealed the presence of residual tensile stresses in the near-ablated surface. HF chemical thinning of the sample showed the thickness of ablation-affected layer provoking strain was ∼275 nm, a value independent of laser fluence (1.9-4.7 J/cm2) and scanning speed (94 - 220 µm/s). A near-surface mean residual tensile stress of ∼80 MPa was inferred from a thin film-substrate approximation.