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Optical Engineering

Method for suppressing the quantization error of Newton’s rings fringe pattern
Author(s): Ming-feng Lu; Guo-Qiang Ni; Ting-zhu Bai; Ran Tao; Feng Zhang
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Paper Abstract

Newton’s rings fringe pattern is often encountered in optical measurement. The digital processing of the fringe pattern is widely used to enable automatic analysis and improve the accuracy and flexibility. Before digital processing, sampling and quantization are necessary, which introduce quantization errors in the fringe pattern. Quantization errors are always analyzed and suppressed in the Fourier transform (FT) domain. But Newton’s rings fringe pattern is demonstrated to be a two-dimensional chirp signal, and the traditional methods based on the FT domain are not efficient when suppressing quantization errors in such signals with large bandwidth as chirp signals. This paper proposes a method for suppressing quantization errors in the fractional Fourier transform (FRFT) domain, for chirp signals occupies little bandwidth in the FRFT domain. This method has better effect on reduction of quantization errors in the fringe pattern than traditional methods. As an example, a standard Newton’s rings fringe pattern is analyzed in the FRFT domain and then 8.5 dB of improvement in signal-to-quantization-noise ratio and about 1.4 bits of increase in accuracy are obtained compared to the case of the FT domain. Consequently, the image quality of Newton’s rings fringe pattern is improved, which is beneficial to optical metrology.

Paper Details

Date Published: 4 October 2013
PDF: 12 pages
Opt. Eng. 52(10) 103105 doi: 10.1117/1.OE.52.10.103105
Published in: Optical Engineering Volume 52, Issue 10
Show Author Affiliations
Ming-feng Lu, Beijing Institute of Technology (China)
Guo-Qiang Ni, Beijing Institute of Technology (China)
Ting-zhu Bai, Beijing Institute of Technology (China)
Ran Tao, Beijing Institute of Technology (China)
Feng Zhang, Beijing Institute of Technology (China)

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