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Surface figure control for coated optics

United States Patent

March 27, 2001
View the Complete Patent at the US Patent & Trademark Office
A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The optic section has an optical section thickness.sup.2 /optical section diameter ratio of between about 5 to 10 mm, and a thickness variation between front and back surfaces of less than about 10%. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.
Ray-Chaudhuri; Avijit K. (Livermore, CA), Spence; Paul A. (Pleasanton, CA), Kanouff; Michael P. (Livermore, CA)
EUV LLC (Santa Clara, CA)
09/ 164,413
September 30, 1998
The United States Government has rights in this invention pursuant to a Contract between the United States Department of Energy and the Sandia National Laboratories.