Robust Fringe Detection Based on Bi-Wavelet Transform for Self-Mixing Displacement Sensor

Olivier Bernal (1) , Han Cheng Seat (1) , Usman Zabit (2) , Frédéric Surre (3) , Thierry Bosch (1)

1 LAAS-OSE - Équipe Optoélectronique pour les Systèmes Embarqués
2 Riphah International University
3 Department of Electrical and Electronic Engineering, School of Mathematics, Computer Science & Engineering, City University London

A novel signal processing method based on custom-made Wavelet Transform (WT) is presented for robust detection of fringes contained in the interferometric signal of Self-Mixing (SM) laser diode sensors. It enables the measurement of arbitrarily-shaped vibrations even in the corruptive presence of speckle. Our algorithm is based on the pattern recognition capability of the customized WT for identifying SM fringes. Once the fringes have been correctly detected, phase unwrapping methods can be applied to retrieve the complete instantaneous phase of the SM signals. Here, the novelty consists in using two distinct mother wavelets Ψ r (t) and Ψ d (t) particularly designed to distinguish SM patterns as well as the displacement direction. The peaks, i.e. maxima of WT, then allow the detection of the fringes.

Mots clés: self-Mixing interferometry; laser diode; Wavelet Transform; displacement measurements; speckle

Domaines: Optique / photonique

Olivier Bernal, Han Cheng Seat, Usman Zabit, Frédéric Surre, Thierry Bosch. Robust Fringe Detection Based on Bi-Wavelet Transform for Self-Mixing Displacement Sensor. SENSORS, 2015 IEEE , Nov 2015, Busan, South Korea. ⟨10.1109/ICSENS.2015.7370375⟩. ⟨hal-01262273⟩