Nonlinear absorption and optical strength of BaF2 and Al2O3 at the wavelength of 248 nm

An experimental investigation was made of the dependence of the transmission of BaF₂ and Al₂O₃ samples on the intensity of KrF-laser radiation (λ = 248 nm) pulses of 85 ns duration. The two-photon absorption coefficients were found at λ = 248 nm and their values for these two crystals were 0.5 ± 0.2 and 2 ± 1 cm Gw^-1. The surface and bulk laser breakdown thresholds were determined for these samples.