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12 December 1994 High-speed fringe analysis method using frequency demodulation technology
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Interferometer fringe pattern analysis is a very precise measuring method. However, this analysis method has not received significant attention in industry as a result of the long calculation time for an operation. The majority of conventional computer analysis methods process an image in the spatial domain using sophisticated algorithms. A new time domain fringe analysis technique is discussed in this paper. Until fringe analysis data can be processed at high speeds using parallel picture processing systems, fringe analysis in the spatial domain is not practical. In order to reduce the calculation time, the fringes imaged on CCD sensor are processed as analog data in the time domain in this paper. The fringes are spatial information on a CCD sensor. The fringes on the CCD sensor are converted to a synchronous electrical signal by the CCD driving clock pulse. The analog signal, which corresponds to the fringes on the CCD sensor, is analyzed using an electrical circuit. The time-instantaneous frequency and phase of the fringes are detected by frequency-demodulating and integrating the signal, respectively. This proposed system can perform high speed fringe analysis operations in 10 msec a line of CCD. The experimental results show that the new fringe analysis is a very high speed processing method and equally as accurate as the FFT method and the fringe scanning method. It is likely that this new fringe analysis method will be a very useful technique for interferometric fringe analysis requirement in industry.
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Yasuhiko Arai, Shunsuke Yokozeki, and Tomoharu Yamada "High-speed fringe analysis method using frequency demodulation technology", Proc. SPIE 2340, Interferometry '94: New Techniques and Analysis in Optical Measurements, (12 December 1994);

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