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Proceedings Paper

The position shifting of frequency spectrum of Fourier transform in the application of aspheric surface testing
Author(s): Junmiao Weng; Yongying Yang; Dong Liu; Yibing Shen; Yongmo Zhuo
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Paper Abstract

In the measurement of aspheric surfaces, spatial phase modulation technology is always combined. With a tilt, the linear spatial carrier is introduced to enhance the signal noise ratio (SNR). Then using DFT on the interferogram, after spectrum shifting, the first order spectrum filter and IDFT, the wavefront phase of aspheric surface is obtained. In this paper, the traditional way to introduce spatial carrier, namely that the center of the first order spectrum is positioned on the x axis, is analyzed. This method exist a limitation which may influence the testing result. Thus a new method is put forward here. Make sure the slope of spatial carrier is unvaried, and transfer the first order spectrum to the bisector of x axis and y axis. This change can not only reserve the low frequency components of the first order spectrum, but also keep the high frequency components at a large extent. So in some circumstance, the wavefront phase of aspheric surface with a large PV value can't be recovered accurately by the traditional spatial carrier way, but it can be recovered accurately by the new way. This greatly expands the testing range of wavefront of aspheric surface.

Paper Details

Date Published: 4 January 2008
PDF: 9 pages
Proc. SPIE 6837, Information Optics and Photonics Technologies II, 68370G (4 January 2008); doi: 10.1117/12.760148
Show Author Affiliations
Junmiao Weng, Zhejiang Univ. (China)
Yongying Yang, Zhejiang Univ. (China)
Dong Liu, Zhejiang Univ. (China)
Yibing Shen, Zhejiang Univ. (China)
Yongmo Zhuo, Zhejiang Univ. (China)

Published in SPIE Proceedings Vol. 6837:
Information Optics and Photonics Technologies II
Guoguang Mu; Feijun Song; Francis T. S. Yu; Suganda Jutamulia, Editor(s)

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