The Study, Based On Square-wave Phase-shift Laser Ranging System

The laser ranging is a technology for precision measurement, it is developing along with the development of the laser technology, which is extensively used in the military field and the civil field because of the good accuracy.This paper introduced a laser ranging system which was based on the square wave. By using FFT and analyzing the spectrum, we implement the phase-detecting synchronously for the first-harmonic and the harmonics, then proceed to calculate the distance. Comparing with the traditional phase-shifted laser range finder, the method could implement the ranging with multifrequency by using single modulated frequency. It could not only solve the contradiction of the range and the precision, but has high degree of accuracy and wide range, simplify the hardware design, and reduce the cost.This paper introduced the theory of phase distance measurement, analyzed various testing methods and expatiated the hardware and the software for the proposal system. The hardware mainly included the emitting circuit of the laser light, receiving circuit and high speed data acquisition circuit. In the software design, we used the window function to improve the resolution of the spectrum, then improve the precision for measurement. In the end, the paper gave the outline of the processing result of the experiment based on Matlab, and analyzed the factors which caused experiment errors.At last, the improvement for the system was brought forward, and research was summarized and expected in this paper.