Transmissivity testing of calcium fluoride windows under high pulse repetition rate laser irradiation at 193 nm

It is hard to judge quality of CaF 2 window from its nominal specification, because suppliers are used to testing products performance under relatively weak spectral linesfrom lamp, which can not tell the real operation behavior of CaF 2 window under intense laser irradiation. We report a method of testing the transmissivity of three different grade commercially available CaF 2 windows under high pulse repetition rate laser irradiation at 193nm, and the lab prototype of test module distinguishes them well with a repeatability better than 2%.