Abstract
Self-mixing interferometry (SMI) is a promising non-contact sensing technology, which has attracted much research attention in the last few decades. The SMI effect takes place when a small portion of laser is back-scattered from an external target and re-enters the laser diode (LD) internal cavity. A typical sensing system using an SMI configuration consists of an LD as the laser source, a target to reflect the laser, a photo diode (PD) to capture the optical signal. This configuration indicates the SMI-based sensing technology’s merits of minimum part-count scheme, low cost in implementation and ease in optical alignment. Various SMI-based sensing applications have been reported, including the measurement of displacement, velocity, vibration, laser related parameters, thickness, mechanical resonance, imaging, material parameter measurement, near-field microscopy, chaotic radar, acoustic detection, biomedical applications, etc.