Nonintrusive Acoustic Measurements by Optical Feedback Interferometry

In this PhD we present the development of a Class 1 microphone using Optical Feedback Interferometry. The acoustic waves are measured thought the acoustooptic effect. We build a dedicated, repeatable and robust experiment showing the impact of the fringe shape on acquisitions of sub-⁄/2 optical path variations. We demonstrate experimentally that the aquired signal amplitude is linearly coupled to the slope of the fringe, a result not yet explicitly published in the OFI literature. As a second research subject in this PhD we present a demonstrator of the Acoustic LIDAR by Optical Feedback Interferometry for the remote acquisitions of acoustic waves. We develop a demodulation algorithm that extracts the acoustic information from a flow of particles that is made to oscillate by an acoustic wave. The experimental demonstrator is capable of acquiring acoustic waves remotely at over 11 m from the detector