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13 January 1992 Final surface error correction of an off-axis aspheric petal by ion figuring
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The final surface figure error correction of a 1.3 m ULETM frit-bonded, ultra- lightweight, off-axis primary mirror petal was successfully completed using the ion figuring process. The petal was a concave aspheric optical element. Ion figuring is an optical fabrication method that provides highly controlled error correction of previously polished surfaces using a directed, inert and neutralized ion beam to physically sputter material from the optic surface. The surface figure error of the petal following conventional polishing was 5.02 (lambda) p-v, 0.62 (lambda) rms, and was improved to 0.17 (lambda) p-v, 0.015 (lambda) rms in four process (test-ion figure) iterations ((lambda) equals 632.8 nm). A multi-iteration process sequence was selected to address the various surface figure error volume and spatial frequency components and involved applying three different beam removal functions. The benefits of ion figuring a complex shaped optic using multiple figuring-testing iterations were clearly demonstrated.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Lynn N. Allen, John J. Hannon, and Richard W. Wambach "Final surface error correction of an off-axis aspheric petal by ion figuring", Proc. SPIE 1543, Active and Adaptive Optical Components, (13 January 1992); doi: 10.1117/12.51181;


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