Electro optic sensor for high precision absolute distance measurement using multiwavelength interferometry.

A prototype multi-wavelength interferometric, phase shifting distance sensor based on linear electro optic effect has been demonstrated in this work to improve the measurement speed of a commercial four-wavelength interferometer. Experimental results revealed the phase modulation ability of the sensor, preserving equivalent efficiency for nanometer-scale absolute distance measurement similar to present piezoelectricity driven mechanical phase modulation. The electro optic sensor working under free beam propagation can significantly overcome the limitations experienced by mechanical phase modulation technique such as the restricted value for the modulating frequency and as well the high driving voltage requirement.