Optical Feedback Interferometry

Abstract

This chapter presents an overview of the self-mixing effect in lasers for sensing purposes. The basic theory of the self-mixing effect is presented for a weak feedback. The influence of a moderate and a strong feedback are then discussed before examining some specific cases: • multiple optical feedback due to an asymmetric external cavity • multiple mode lasing by laser diode • influence of the speckle effect on self-mixing interferometry The main representative sensing applications are then presented and discussed including displacement, velocity, profile, vibration measurements and correlated applications like measurements for medicine, sound reproduction, modal analysis, angle measurements, 3-D vision or even massmarket mobile telephones.