Radiation resistance of optical materials for windows of UV and VUV excimer lasers

The behaviour of modern quartz glasses and fluo-rite is studied experimentally under a prolonged action of the 280-keV electron beam pulses and an overall fluence of up to ~30 kJ cm^-2. The induced absorption in all investigated mate-rials saturates with increasing the fluence. The maximum variation of transmission in high-purity CaF₂ samples does not exceed 5% – 10% in the wavelength range 120 – 1000 nm. Quasi-stationary absorption in the region of ~180 – 300 nm in the KS-4V quartz glass sample is approximately four times smaller than that in the KU-1 quartz glass and half the value for Corning 7980 glasses.