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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.
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