Detection of Self-Mixing Interferometric Fringes of a Laser Sensor Using Matched Filter

Self-Mixing (SM) is a promising technique for sensing vibration, distance, velocity etc. To retrieve accurate metric measurements from an acquired SM signal, it is necessary to correctly detect all interferometric fringes. Traditionally, SM fringes are detected by a derivative based threshold (DBT) scheme. However, such a scheme gives correct results only for SM signals with high signal-to-noise ratio (SNR) and moderate optical feedback regime. So, in this paper, a better fringe detection method, based on Matched Filter (MF), is proposed which has provided correct SM fringe detection even in case of low SNR and weak optical feedback regime. The proposed approach has resulted in fringe detection accuracy of 100% for a low SNR SM signal belonging to the weak feedback regime