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Proceedings Paper

Material removal characteristics of orthogonal velocity polishing tool for efficient fabrication of CVD SiC mirror surfaces
Author(s): Hyunju Seo; Jeong-Yeol Han; Sug-Whan Kim; Sehyun Seong; Siyoung Yoon; Kyungmook Lee; Haengbok Lee
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Paper Abstract

Today, CVD SiC mirrors are readily available in the market. However, it is well known to the community that the key surface fabrication processes and, in particular, the material removal characteristics of the CVD SiC mirror surface varies sensitively depending on the shop floor polishing and figuring variables. We investigated the material removal characteristics of CVD SiC mirror surfaces using a new and patented polishing tool called orthogonal velocity tool (OVT) that employs two orthogonal velocity fields generated simultaneously during polishing and figuring machine runs. We built an in-house OVT machine and its operating principle allows for generation of pseudo Gaussian shapes of material removal from the target surface. The shapes are very similar to the tool influence functions (TIFs) of other polishing machine such as IRP series polishing machines from Zeeko. Using two CVD SiC mirrors of 150 mm in diameter and flat surface, we ran trial material removal experiments over the machine run parameter ranges from 12.901 to 25.867 psi in pressure, 0.086 m/sec to 0.147 m/sec in tool linear velocity, and 5 to 15 sec in dwell time. An in-house developed data analysis program was used to obtain a number of Gaussian shaped TIFs and the resulting material removal coefficient varies from 3.35 to 9.46 um/psi hour m/sec with the mean value to 5.90 ± 1.26(standard deviation). We report the technical details of the new OVT machine, of the data analysis program, of the experiments and the results together with the implications to the future development of the OVT machine and process for large CVD SiC mirror surfaces.

Paper Details

Date Published: 8 September 2015
PDF: 10 pages
Proc. SPIE 9575, Optical Manufacturing and Testing XI, 95750N (8 September 2015); doi: 10.1117/12.2188805
Show Author Affiliations
Hyunju Seo, Yonsei Univ. (Korea, Republic of)
Korea Astronomy and Space Science Institute (Korea, Republic of)
Jeong-Yeol Han, Korea Astronomy and Space Science Institute (Korea, Republic of)
Sug-Whan Kim, Yonsei Univ. (Korea, Republic of)
Sehyun Seong, Yonsei Univ. (Korea, Republic of)
SphereDyne Co., Ltd. (Korea, Republic of)
Siyoung Yoon, Hanwha Thales Co., Ltd. (Korea, Republic of)
Kyungmook Lee, Hanwha Thales Co., Ltd. (Korea, Republic of)
Haengbok Lee, Agency for Defense Development (Korea, Republic of)

Published in SPIE Proceedings Vol. 9575:
Optical Manufacturing and Testing XI
Oliver W. Fähnle; Ray Williamson; Dae Wook Kim, Editor(s)

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