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Proceedings Paper

Measurement of aspheric mirror by nanoprofiler using normal vector tracing
Author(s): Takao Kitayama; Hiroki Shiraji; Kazuya Yamamura; Katsuyoshi Endo
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Paper Abstract

Aspheric or free-form optics with high accuracy are necessary in many fields such as third-generation synchrotron radiation and extreme-ultraviolet lithography. Therefore the demand of measurement method for aspherical or free-form surface with nanometer accuracy increases. Purpose of our study is to develop a non-contact measurement technology for aspheric or free-form surfaces directly with high repeatability. To achieve this purpose we have developed threedimensional Nanoprofiler which detects normal vectors of sample surface. The measurement principle is based on the straightness of laser light and the accurate motion of rotational goniometers. This machine consists of four rotational stages, one translational stage and optical head which has the quadrant photodiode (QPD) and laser source. In this measurement method, we conform the incident light beam to reflect the beam by controlling five stages and determine the normal vectors and the coordinates of the surface from signal of goniometers, translational stage and QPD. We can obtain three-dimensional figure from the normal vectors and their coordinates by surface reconstruction algorithm. To evaluate performance of this machine we measure a concave aspheric mirror with diameter of 150 mm. As a result we achieve to measure large area of 150mm diameter. And we observe influence of systematic errors which the machine has. Then we simulated the influence and subtracted it from measurement result.

Paper Details

Date Published: 12 October 2016
PDF: 7 pages
Proc. SPIE 9962, Advances in Metrology for X-Ray and EUV Optics VI, 99620B (12 October 2016); doi: 10.1117/12.2242408
Show Author Affiliations
Takao Kitayama, Osaka Univ. (Japan)
Hiroki Shiraji, Osaka Univ. (Japan)
Kazuya Yamamura, Osaka Univ. (Japan)
Katsuyoshi Endo, Osaka Univ. (Japan)

Published in SPIE Proceedings Vol. 9962:
Advances in Metrology for X-Ray and EUV Optics VI
Lahsen Assoufid; Haruhiko Ohashi; Anand Krishna Asundi, Editor(s)

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