Phase-shifting point-diffraction interferometry at 193 nm

Phase-shifting point-diffraction interferometry at the 193-nm wavelength su itable for highly accurate measurement of wave-front aberration is introduc ed. The interferometer preserves the advantages of the previously described extreme-ultraviolet phase-shifting point-diffraction interferometer but of fers higher relative efficiency. Wave-front measurement of an imaging syste m, operating at the 193-nm wavelength, is reported. Direct measurement of t he refractive-index change in a deep-ultraviolet radiation-damaged fused-si lica sample is also presented as an application. (C) 2000 Optical Society o f America OCIS codes: 120.3180, 050.5080, 120.3940, 120.5050, 030.1640, 350 .2770, 110.3960.