A wavefront modulating optical element device employs two or more materials lithographically patterned with programmed thickness profiles. The spatially-varying thickness profiles are chosen to yield arbitrary relative phase-shift and attenuation upon transmission. The device can be designed to create...http://www.google.de/patents/US7027226?utm_source=gb-gplus-sharePatent US7027226 - Diffractive optical element for extreme ultraviolet wavefront control
