Micro-vibration measurement using self-mixing interferometry with an intracavity frequency-doubling solid-state laser

Abstract

The self-mixing interference (SMI) is an emerging sensing technology, which has the advantages of self-collimation and high sensitivity. However, current theoretical analyses of SMI are mostly based on semiconductor laser, while there are relatively few analyses based on solid-state laser especially 532 nm solid-state laser. Simultaneously, the resolution of SMI is easily affected by laser noise and environmental perturbation. In this paper, the theoretical model of SMI based on a 532 nm solid-state laser is established by rotating vector addition model. And a noise suppression method with dual electro-optic modulation is proposed. Experiments show that the self-mixing interferometry constructed with a 532 nm solid-state laser and dual electro-optical crystals can resolve the square wave motions with a peak-to-peak value less than 10 nm, and the short-term resolution is better than 1 nm. Moreover, the system can accurately reconstruct sinusoidal vibrations with peak-to-peak values from 10 to 5000 nm, vibrations with extremely weak feedback light, and non-sinusoidal vibrations.