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The study of sub-surface damage distributions during grinding process on different abrasion materials
Author(s): Ching-Hsiang Kuo; Chien-Yao Huang; Zong-Ru Yu; Shyu-Cheng Shu; Keng-Shou Chang; Wei-Yao Hsu
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Paper Abstract

The grinding process is the primary technology for curvature generation (CG) on glass optics. The higher material removal rate (MRR) leads to deeper sub-surface damage (SSD) on lens surface. The SSD must be removed by following lapping and polishing processes to ensure the lens quality. However, these are not an easy and an efficient process to remove the SSD from ground surface directly for aspheric surfaces with tens or hundreds microns departure from bestfit- sphere (BFS). An efficient fabrication procedure for large aspheric departure on glass materials must be considered. We propose 3-step fabrication procedures for aspheric surface with larger departure. 1st step is to generate a specific aspheric surface with depth less than 10 μm of SSD residual. 2nd step is to remove SSD and keep the aspheric form by using Zeeko polisher with higher MRR pad. Final step is to figure and finish the aspheric surface by using QED MRF machine. In this study, we focus on the 1st step to investigate the residual depth of SSD after grinding process on different abrasion materials. The materials of tested part are fused silica, S-NPH2, and S-PHM52. The cross grinding would be configured and depth of SSD/surface roughness would be evaluated in this study. The characteristic of SSD could be observed after etching by confocal microscope. The experimental results show the depth of SSD below 31.1 μm with #400 grinding wheel. And the near 10 μm depth of SSD would be achieved with #1,000 grinding wheel. It means the aspherization polishing on large parts with large departure from best fit sphere would be replaced. The fabrication of large aspheric part would be efficient.

Paper Details

Date Published: 16 October 2017
PDF: 6 pages
Proc. SPIE 10448, Optifab 2017, 1044823 (16 October 2017); doi: 10.1117/12.2279673
Show Author Affiliations
Ching-Hsiang Kuo, National Applied Research Labs. (Taiwan)
National Chung-Hsing Univ. (Taiwan)
Chien-Yao Huang, National Applied Research Labs. (Taiwan)
National Chung-Hsing Univ. (Taiwan)
Zong-Ru Yu, National Applied Research Labs. (Taiwan)
National Chung-Hsing Univ. (Taiwan)
Shyu-Cheng Shu, National Applied Research Labs. (Taiwan)
National Chung-Hsing Univ. (Taiwan)
Keng-Shou Chang, National Applied Research Labs. (Taiwan)
National Chung-Hsing Univ. (Taiwan)
Wei-Yao Hsu, National Applied Research Labs. (Taiwan)
National Chung-Hsing Univ. (Taiwan)


Published in SPIE Proceedings Vol. 10448:
Optifab 2017
Julie L. Bentley; Sebastian Stoebenau, Editor(s)

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