Two-wavelength interferometric signal processing by recurrence filtering method

Two-wavelength interferometry technique provides accurate measurement of geometric values in extended range of measurement definition. We propose the approach to two-wavelength interferometric signal processing based on recurrence data filtering. Interferometer is illuminated by monochromatic light source on two wavelength simultaneously. The position of reference mirror is changed step by step inside the range defined by "synthesized" wavelength. It is used the recurrence least-square fitting algorithm to estimate the two-wavelength interferometric signal parameters dynamically taking into account the particularities of the signal model. To suppress the background and noise influence the discrete recurrence filters with linear phase characteristics have been used.