There exist numerous interferometric methods for absolute distance measurement

but it is difficult to construct compact low-cost measuring systems because of the need of a lot of optical devices for most of them.Featured in simple structure

low cost and high accuracy

the interferometry based on optical feedback self-mixing interference has in recent years attracted extensive attention in the field of measurement.This paper analyzes the theories of laser self-mixing interference and frequency modulation

sets up an absolute distance measurement model and conducts calculations and simulations

the result of which shows that uses can be made of the frequency modulation theory to measure the absolute distance of the targets.