Self-mixing interferometry with mutual independent orthogonal polarized light.

A self-mixing interferometry with mutual independent orthogonal polarized light is introduced. Its most important feature is that two mutual independent orthogonal lights are used as measuring and reference light. Frequency shifting and polarization multiplexing technologies are used in the proposed optical system. Phase variation of the two orthogonal polarized beams is simultaneously measured through heterodyne demodulation with a lock-in amplifier. The phase difference of the orthogonal polarized light accurately reflects the target displacement. The target in this system is a non-cooperative object which is different from a traditional Michelson interferometer. The primary experimental results show that this kind of self-mixing interferometry is very feasible. Under typical room conditions, the system's short-term resolution is better than 2 nm.