Improving the measurement performance for a self-mixing interferometry-based displacement sensing system

Approaches that are, to our knowledge, novel, are proposed in this paper to improve the accuracy performance

of self-mixing interferometry (SMI) for displacement measurement. First, the characteristics

associated with signals observed in SMI systems are studied, based on which a new procedure is proposed

for achieving accurate estimation of the laser phase. The studies also revealed the reasons for the inherent

errors associated with the existing SMI-based techniques for displacement measurement. Then,

this paper presents a new method for estimating the optical feedback level factor (denoted by C) in real

time. Combining the new algorithms for estimating the laser phase and updating C value, the paper

finally presents a novel technique for displacement measurement with improved accuracy performance

in contrast to existing techniques. The proposed technique is verified by both simulation and experimental data.