An improved intersection feedback micro-radian angle-measurement system based on the Laser self-mixing interferometry

Abstract

An improved intersection feedback laser self-mixing sensing system is presented for measuring the micro-radian angle by means of the self-mixing interference effect. The experimental results demonstrate that this angle-measurement system can effectively prevent the low resolution and narrow measurement-angle range existing in traditional angle-measurement techniques. Meanwhile, the theoretical illustration and experimental analysis elucidate that both the different radii of the rotary disk and the different angles between two mirrors significantly affect angle-measurement resolution. Accordingly, over the full-circle ranging from 0 to 2π rad, the practical measurement resolution can reach up to 6.28 μrad, which is in good consistency with the simulated value. Furthermore, the absolute error of the self-mixing angle experimental measurement system is less than ± 0.97 μrad, and the relative error is less than 2.40×10−6 μrad, both of which indicate better feasibility and system reliability. As a result, it can be further extended to other applications owing to its small space size and high measurement accuracy.