Optical fabrication tolerances for synchrotron beamline optics

Abstract

Recent advances in optical fabrication techniques have resulted in a resurgence of activity in the field of x-ray and extreme ultraviolet (EUV) imaging systems. However, traditional optical design and analysis techniques (geometrical ray tracing) are woefully inadequate for predicting the performance of high resolution imaging systems at these very short wavelengths. Diffraction effects of grazing incidence optics and small angle scattering effects due to residual optical fabrication errors will frequently dominate geometrical design errors in the degradation of image quality. Surface scattering theory must be implemented to model the image degradation effects of residual surface irregularities over the entire range of relevant spatial frequencies. These include small angle scattering effects due to mid spatial frequency surface errors falling between the traditional figure and finish specifications. Performance predictions can then be presented parametrically to provide some insight into the optical fabrication tolerances necessary to meet a particular image quality requirement.