Abstract

Multilayer soft x-ray coatings on curved optical surfaces may affect the quality of the image in the imaging system due to variation in phase and reflectance across the aperture. Because the reflectance stopband for these coatings is narrow, these variations tend to be large. The multilayer coating reflectance and phase variations depend on both wavelength and incidence angle of the radiation going through the imaging system. Figure 1 shows these dependencies for a multilayer coating containing 20 bilayers of Mo/Si. As can be seen from this figure for a given wavelength the phase change due to incidence angle variation can be significant.

© 1991 Optical Society of America