Abstract

Itek Optical Systems has developed computer-controlled optical surfacing (CCOS) processes and equipment for the rapid fabrication of large aspheric optics. An orbiting tool, considerably smaller than the optic, is moved across the optic surface under computer control. Low-spatial-frequency errors are corrected by varying the velocity of the tool over the optic surface to accurately control material removal. High-spatial-frequency errors are eradicated by the pad as it compresses to fit the surface, producing greater pressure and more removal at the higher surface regions under the pad. CCOS was used to fabricate seven 2 m off-axis aspheric optics. These thin facesheets were worked close to their actual edges during both grinding and polishing so that they could be used in a segmented mirror. Excellent grinding and polishing results were achieved for all facesheets. Also, the figure convergence was improved during the operation; the last facesheet was polished in only 11 weeks. The CCOS operation provides efficient automated fabrication. With a number of stations operating on multiple shifts, the intensive optical fabrication needs of the next decade can be met.

© 1990 Optical Society of America