A Self-Mixing Displacement Sensor With Fringe-Loss Compensation for Harmonic Vibrations

The disappearance of self-mixing fringes in the moderate feedback regime decreases the displacement measurement accuracy. The proposed method detects and compensates the fringe-loss, to limit the error to around 40 nm for micrometer range harmonic amplitude displacements. Moreover, it can also treat arbitrary displacements without any time-consuming optimization procedure and is suitable for implementation in a real-time displacement sensor.