4 October 2013 Method for suppressing the quantization error of Newton’s rings fringe pattern
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Optical Engineering, 52(10), 103105 (2013). doi:10.1117/1.OE.52.10.103105
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.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Ming-feng Lu, Guo-Qiang Ni, Ting-zhu Bai, Ran Tao, Feng Zhang, "Method for suppressing the quantization error of Newton’s rings fringe pattern," Optical Engineering 52(10), 103105 (4 October 2013). http://dx.doi.org/10.1117/1.OE.52.10.103105
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KEYWORDS
Quantization

Fringe analysis

Fourier transforms

Error analysis

Signal to noise ratio

Commercial off the shelf technology

Signal processing

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