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Design and tolerance analysis of a transmission sphere by interferometer model
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Paper Abstract

The design of a 6-in, f/2.2 transmission sphere for Fizeau interferometry is presented in this paper. To predict the actual performance during design phase, we build an interferometer model combined with tolerance analysis in Zemax. Evaluating focus imaging is not enough for a double pass optical system. Thus, we study the interferometer model that includes system error, wavefronts reflected from reference surface and tested surface. Firstly, we generate a deformation map of the tested surface. Because of multiple configurations in Zemax, we can get the test wavefront and the reference wavefront reflected from the tested surface and the reference surface of transmission sphere respectively. According to the theory of interferometry, we subtract both wavefronts to acquire the phase of tested surface. Zernike polynomial is applied to transfer the map from phase to sag and to remove piston, tilt and power. The restored map is the same as original map; because of no system error exists. Secondly, perturbed tolerances including fabrication of lenses and assembly are considered. The system error occurs because the test and reference beam are no longer common path perfectly. The restored map is inaccurate while the system error is added. Although the system error can be subtracted by calibration, it should be still controlled within a small range to avoid calibration error. Generally the reference wavefront error including the system error and the irregularity of the reference surface of 6-in transmission sphere is measured within peak-to-valley (PV) 0.1 λ (λ=0.6328 um), which is not easy to approach. Consequently, it is necessary to predict the value of system error before manufacture. Finally, a prototype is developed and tested by a reference surface with PV 0.1 λ irregularity.

Paper Details

Date Published: 3 September 2015
PDF: 9 pages
Proc. SPIE 9582, Optical System Alignment, Tolerancing, and Verification IX, 958208 (3 September 2015); doi: 10.1117/12.2187759
Show Author Affiliations
Wei-Jei Peng, Instrument Technology Research Ctr. (Taiwan)
Cheng-Fong Ho, Instrument Technology Research Ctr. (Taiwan)
Wen-Lung Lin, Instrument Technology Research Ctr. (Taiwan)
Zong-Ru Yu, Instrument Technology Research Ctr. (Taiwan)
Chien-Yao Huang, Instrument Technology Research Ctr. (Taiwan)
Wei-Yao Hsu, Instrument Technology Research Ctr. (Taiwan)

Published in SPIE Proceedings Vol. 9582:
Optical System Alignment, Tolerancing, and Verification IX
José Sasián; Richard N. Youngworth, Editor(s)

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