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We propose in this paper a digital hologram analysis based on a parametric method with the purpose of determining the distance between a small spherical particle and the sensor. The in-line Fraunhofer hologram of the particle is considered. The parametric method is implemented with a sliding window to extract the frequency of the chirped signal. A good agreement between simulations and results obtained by other authors is observed.

Interferometry associated with an external cavity laser of long coherence length and broad wavelength tuning range shows promising features for use in measurements of absolute distance. As far as we know, the processing of the interferometric signals has until now been performed by Fourier analysis or fringe counting. Here we report on the use of an autoregressive model to determine fringe pattern frequencies. This concept was applied to an interferometric device fed by a continuously tunable external-cavity laser diode operating at a central wavelength near 1.5 μm. A standard uncertainty of 4 × 10^-5 without averaging at a distance of 4.7 m was obtained.