Interference of two beams in a He-Ne laser with optical feedback

This article makes a research in theory and experiment on the changes of the interference signal and the laser intensity of an interferometer with optical feedback in a He-Ne laser.When the main feedback mirror moves,the curve of the laser output intensity is a sine wave but the interference signal is a curve with two peaks in a period.One peak is higher than the other one.When the feedback mirror changes its moving direction,the order that the two peaks come out will change too.The article analyses the experimental results in theory and simulates the interference signal and the laser intensity signal.The simulation results are in good agreement with the experiment results.A measuring method is discussed which can judge the moving direction of the moving object easily and this method is easy to be realized.