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2 August 2004 Generalized multifrequency interferometric techniques for absolute phase measurement
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We present two novel multi-frequency techniques for absolute range measurement in interferometry. The first employs a generalised optimum multi-frequency technique for maximising the measurement range by careful selection of the measurement frequencies. Furthermore, the approach utilises the minimum number of measurement wavelengths and hence reduces the complexity of an interferometer for a given application. The second technique uses the same measurement frequency selection approach as in the well-known technique of excess fractions, but introduces a novel algorithm based on the Chinese remainder theorem to produce reliable fringe order information in the presence of phase measurement noise. A comparison of these techniques with the method of excess fractions has been performed by computer simulation showing that the generalised optimum multi-frequency approach offers the best combination of process speed and measurement reliability. The new techniques have been successfully applied to data from coherent and incoherent fringe projection systems to produce shape data. The results from an initial investigation into a fibre interferometer for high speed single point ranging with 2 measurement frequencies is also presented.
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Catherine E. Towers, David Peter Towers, and Julian D.C. Jones "Generalized multifrequency interferometric techniques for absolute phase measurement", Proc. SPIE 5531, Interferometry XII: Techniques and Analysis, (2 August 2004);

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