INFLUENCE OF FABRICATION ERRORS ON WOLTER MIRROR IMAGING PERFORMANCE

The resolution of the Wolter mirror, which is utilized as an objective in soft-x-ray microscopes, is limited by fabrication errors. We studi ed the relation between fabrication errors and imaging performance of the Wolter mirror to determine how this performance could be improved. Figure errors, which are characterized by low spatial frequency, were analyzed by ray tracing, and surface roughness, characterized by high spatial frequency, was analyzed by modified ray tracing. Modified ray tracing was based on ray tracing but took scattering into account. Th e results of these analyses were compared with experimental data. As a result, we obtained a simple and practical fabricating tolerance crit erion that may be employed to obtain higher Wolter mirror resolution. Additionally, we discuss problems in current Wolter mirror fabrication techniques and the changes that might be made in both the design and the fabrication process to improve imaging performance. (C) 1998 Optic al Society of America.