The present invention is directed at a coherence test reticle or lithographic plate, and a method for testing the coherence of a laser beam using the test reticle. The quality or coherence of the laser beam is measured by illuminating the test reticle and the recording and/or analyzing the optical patterns...http://www.google.de/patents/US6934038?utm_source=gb-gplus-sharePatent US6934038 - Method for optical system coherence testing
