A new design of laser phase-shift range finder independent of environmental conditions and thermal drift

Abstract

This paper presents a technique to improve the performance of laser phase-shift range finders. The phase measurement is performed by using a new method to extract the phase-shift data from the peak of received and transmitted intermediate frequency signal amplitudes. The pulse width modulation is used to minimize the noise effect and enhance the signal amplitude measurement. The advantages of proposed system over others are its ability of proper isolation, which reduces crosstalk, and independency of frequency thermal drift. Theoretical calculations and experimental results have shown the accuracy better than 2mm over measuring distance range of 0.3m-163m.