THE PHYSICAL PRINCIPLES OF WAVELENGTH-SHIFT INTERFEROMETRIC LASER RANGEFINDERS

In this paper, we reviewed the recent progress in dynamic interferometry applied to optical distance measurement devices. These techniques are based on modulating laser diodes to obtain a continuous wavelength-shift. Measurements could be done by a fringe counting technique or by detecting the beat frequency that is proportional to the time-of-flight. This paper shows too the importance of the spectral analysis of the photo-detected signal. A signal processing allows the use of multiple-beam interferometers with multiple reflectors. It's also possible to determine absolute distances with rough targets from the ratio of the amplitudes of two harmonics.