Absolute distance measurement with a sampling type of double sinusoidal phase-modulating laser diode interferometer

Advanced materials and devices for sensing and imaging : 17-18 October 2002, Shanghai, China. : Oct 2002, Shanghai, ChinaWe propose a new range finding technique that uses two-wavelength interferometry. The system we propose uses a single laser diode to realize a two-wavelength interferometer, which expands measurement range. The single light-source allows us to simplify the optical setup. Our device generates two independent interference signals with respect to the wavelengths generated by offset current. The external disturbances on these interference signals are eliminated by the feedback control. Although the feedback control eliminates disturbance as well as the information about the distance, we are able to detect the distance from the phase difference between those compensated interference signals