Quasi-Linear Displacement Measurement with Laser Feedback Interferometry

In laser feedback interferometry (LFI), a laser diode is shone onto a target and the reflection from that target is injected back into the laser cavity. It has been demonstrated that changes in the laser dynamics induced by the fed back light can be exploited to measure target displacement, absolute position, or velocity [1,2]. In particular, displacement sensors have been demonstrated to reach minimum detectible displacements (MDD) as small as a few nanometers. However, such small MDD levels require post-processing of the measured signals and/or to modify, and thus increase the complexity of, the LFI setup [3,4].