Testing of the optics used in lithography illumination systems with a system that permits use of relatively high intensity illumination radiation originating from an extended non-coherent radiation source

摘要

Point diffraction interferometer has a light source (1) with an input side hole mask (2), a test object region (4) for optics (9) to be tested, means (5, 6) for generation of test and reference beams with an output side hole mask (6) and evaluation means (7, 8) for evaluation of the interference pattern (16) arising from the superimposed reference and test beams. The input and output side hole masks comprise 2-D fields of quasi-point type through holes (12, 15).