PERFORMANCE PREDICTIONS OF A SCHWARZSCHILD IMAGING MICROSCOPE FOR SOFT-X-RAY APPLICATIONS

The design of a Schwarzschild imaging microscope for soft x-ray applic ations has been reported by Hoover and Shealy. Based upon a geometrica l ray-trace analysis of the residual design errors, diffraction-limite d performance at a wavelength of 100 Angstrom was predicted over an ob ject size (diameter) of 0.4 mm. We expand on the analysis of that desi gn by determining the total image degradation due to diffraction, geom etrical aberrations, and scattering effects due to residual optical fa brication errors. A linear systems treatment of surface scattering phe nomena is used to model the image degradation effects of surface irreg ularities over the entire range of relevant spatial frequencies. This includes small angle scattering effects due to mid spatial frequency s urface errors falling between the traditional ''figure'' and ''finish' ' specifications. The implementation of this scattering theory as a ge neral performance prediction code is validated by excellent agreement with limited test data for a different Schwarzschild microscope at a w avelength of 73 Angstrom. Finally, image quality predictions are prese nted parametrically to provide insight into the optical fabrication to lerances necessary to meet desired image quality requirements. (C) 199 6 Society of Photo-Optical Instrumentation Engineers.