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Proceedings Paper

λ/100 reference flat for commercially available Fizeau interferometer
Author(s): Y. Kondo; Y. Bitou; Kazuhide Yamauchi
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Paper Abstract

The flatness is one of the important geometric quantity such as a silicon wafer, a photo mask and ultra-precise optics for an extreme ultraviolet lithography, synchrotron radiation facilities and a gravitational wave interferometer. A Fizeau interferometer is in a high accurate flatness measurement equipment. In a Fizeau interferometer, the measurand is a gap distance between a reference flat and a specimen. The measurement accuracy of the Fizeau interferometer is limited by the flatness of the reference flat. The flatness of commercially reference flats is about λ/40 to λ/20 (15 nm - 30 nm). There is strong demand for developing that the flatness of reference flat is less than 10 nm. Thus, we developed a λ/100 (6.3 nm) reference flat which is attachable to a commercial Fizeau interferometer. The measurable diameter of the optical flat was φ100 mm. In the factory fields, the flatness of the reference flat mounted on a commercial Fizeau interferometer is required. We designed the reference flat using the finite element method (FEM) to decrease a deformation by mounting. The developed reference flat was evaluated by a scanning deflectometric profiler (SDP) and an ultra-high accurate Fizeau interferometer. Finally, the reference flat was validated through the evaluation results.

Paper Details

Date Published: 25 October 2016
PDF: 5 pages
Proc. SPIE 9687, 8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Subnanometer Accuracy Measurement for Synchrotron Optics and X-Ray Optics, 968708 (25 October 2016); doi: 10.1117/12.2242806
Show Author Affiliations
Y. Kondo, National Metrology Institute of Japan (Japan)
Y. Bitou, National Metrology Institute of Japan (Japan)
Kazuhide Yamauchi, Technical Co., Ltd. (Japan)


Published in SPIE Proceedings Vol. 9687:
8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Subnanometer Accuracy Measurement for Synchrotron Optics and X-Ray Optics
Shinan Qian; Mourad Idir; Daniele Cocco; Tiqiao Xiao; Kazuto Yamauchi, Editor(s)

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