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Proceedings Paper

Fabrication of ф 160 mm convex hyperbolic mirror for remote sensing instrument
Author(s): Ching-Hsiang Kuo; Zong-Ru Yu; Cheng-Fang Ho; Wei-Yao Hsu; Fong-Zhi Chen
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Paper Abstract

In this study, efficient polishing processes with inspection procedures for a large convex hyperbolic mirror of Cassegrain optical system are presented. The polishing process combines the techniques of conventional lapping and CNC polishing. We apply the conventional spherical lapping process to quickly remove the sub-surface damage (SSD) layer caused by grinding process and to get the accurate radius of best-fit sphere (BFS) of aspheric surface with fine surface texture simultaneously. Thus the removed material for aspherization process can be minimized and the polishing time for SSD removal can also be reduced substantially. The inspection procedure was carried out by using phase shift interferometer with CGH and stitching technique. To acquire the real surface form error of each sub aperture, the wavefront errors of the reference flat and CGH flat due to gravity effect of the vertical setup are calibrated in advance. Subsequently, we stitch 10 calibrated sub-aperture surface form errors to establish the whole irregularity of the mirror in 160 mm diameter for correction polishing. The final result of the In this study, efficient polishing processes with inspection procedures for a large convex hyperbolic mirror of Cassegrain optical system are presented. The polishing process combines the techniques of conventional lapping and CNC polishing. We apply the conventional spherical lapping process to quickly remove the sub-surface damage (SSD) layer caused by grinding process and to get the accurate radius of best-fit sphere (BFS) of aspheric surface with fine surface texture simultaneously. Thus the removed material for aspherization process can be minimized and the polishing time for SSD removal can also be reduced substantially. The inspection procedure was carried out by using phase shift interferometer with CGH and stitching technique. To acquire the real surface form error of each sub aperture, the wavefront errors of the reference flat and CGH flat due to gravity effect of the vertical setup are calibrated in advance. Subsequently, we stitch 10 calibrated sub-aperture surface form errors to establish the whole irregularity of the mirror in 160 mm diameter for correction polishing. The final result of the Fabrication of ф160 mm Convex Hyperbolic Mirror for Remote Sensing Instrument160 mm convex hyperbolic mirror is 0.15 μm PV and 17.9 nm RMS.160 mm convex hyperbolic mirror is 0.15 μm PV and 17.9 nm RMS.

Paper Details

Date Published: 11 October 2012
PDF: 6 pages
Proc. SPIE 8486, Current Developments in Lens Design and Optical Engineering XIII, 848615 (11 October 2012); doi: 10.1117/12.928349
Show Author Affiliations
Ching-Hsiang Kuo, Instrument Technology Research Ctr. (Taiwan)
Zong-Ru Yu, Instrument Technology Research Ctr. (Taiwan)
Cheng-Fang Ho, Instrument Technology Research Ctr. (Taiwan)
Wei-Yao Hsu, Instrument Technology Research Ctr. (Taiwan)
Fong-Zhi Chen, Instrument Technology Research Ctr. (Taiwan)


Published in SPIE Proceedings Vol. 8486:
Current Developments in Lens Design and Optical Engineering XIII
R. Barry Johnson; Virendra N. Mahajan; Simon Thibault, Editor(s)

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