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Proceedings Paper

Freeform correction polishing for optics with semi-kinematic mounting
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Paper Abstract

Several mounting configurations could be applied to opto-mechanical design for achieving high precise optical system. The retaining ring mounting is simple and cost effective. However, it would deform the optics due to its unpredictable over-constraint forces. The retaining ring can be modified to three small contact areas becoming a semi-kinematic mounting. The semi-kinematic mounting can give a fully constrained in lens assembly and avoid the unpredictable surface deformation. However, there would be still a deformation due to self-weight in large optics especially in vertical setup applications. The self-weight deformation with a semi-kinematic mounting is a stable, repeatable and predictable combination of power and trefoil aberrations. This predictable deformation can be pre-compensated onto the design surface and be corrected by using CNC polisher. Thus it is a freeform surface before mounting to the lens cell. In this study, the freeform correction polishing is demonstrated in a Φ150 lens with semi-kinematic mounting. The clear aperture of the lens is Φ143 mm. We utilize ANSYS simulation software to analyze the lens deformation due to selfweight deformation with semi-kinematic mounting. The simulation results of the self-weight deformation are compared with the measurement results of the assembled lens cell using QED aspheric stitching interferometer (ASI). Then, a freeform surface of a lens with semi-kinematic mounting due to self-weight deformation is verified. This deformation would be corrected by using QED Magnetorheological Finishing (MRF® ) Q-flex 300 polishing machine. The final surface form error of the assembled lens cell after MRF figuring is 0.042 λ in peak to valley (PV).

Paper Details

Date Published: 12 October 2015
PDF: 6 pages
Proc. SPIE 9633, Optifab 2015, 963326 (12 October 2015); doi: 10.1117/12.2195464
Show Author Affiliations
Chien-Yao Huang, National Applied Research Labs. (Taiwan)
Ching-Hsiang Kuo, National Applied Research Labs. (Taiwan)
Wei-Jei Peng, National Applied Research Labs. (Taiwan)
Zong-Ru Yu, National Applied Research Labs. (Taiwan)
Cheng-Fang Ho, National Applied Research Labs. (Taiwan)
Ming-Ying Hsu, National Applied Research Labs. (Taiwan)
Wei-Yao Hsu, National Applied Research Labs. (Taiwan)

Published in SPIE Proceedings Vol. 9633:
Optifab 2015
Julie L. Bentley; Sebastian Stoebenau, Editor(s)

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