PhD defense Hugo Boiron"Thermomechanical analysis of optical fibre coils by studying their Rayleigh backscattering"

"Thermomechanical analysis of optical fibre coils by studying their Rayleigh backscattering"

Abstract:

Numerous applications require knowledge of the position of a mobile in its environment. Despite the progress of global navigation satellite systems, they remain insufficient in the case of sensitive applications. To overcome these difficulties, an inertial measurement unit can be used. It is based on the utilization of three accelerometers and three gyroscopes. The Fiber Optic Gyroscope (FOG) is based on the Sagnac-Laue effect : two counterpropagative waves are sent into an optical fiber coil rotating around its axis. The interferometric phase difference measured between the two waves is proportional to the rotational rate. However, a thermal loading disturbs the quality of the FOG measurements. The objective of this thesis is to set up an experimental device allowing to measure the thermal bias drift induced by a homogeneous thermal loading resulting in a non-homogeneous strain distribution in the coil. These deformations are measured using the Rayleigh-Optical frequency domain reflectometry method. In addition to its main objective, this thesis has allowed the study of the influence of many parameters on the thermomechanical behavior of fiber optic coils such as humidity or coil geometry.

Jury:

• Emmanuel Marin, Laboratoire Hubert Curien, Supervisor
• Adriana Morana, Laboratoire Hubert Curien, Co-Supervisor
• Maxime Rattier, Exail, Co-Supervisor
• Hervé C. Lefèvre, Exail, Co-Supervisor
• Sylvain Girard, Laboratoire Hubert Curien, Examiner
• Pascal Picart, Laboratoire d'Acoustique LAUM, Université du Mans, Examiner
• Emmanuelle Peter, Safran Space, Examiner
• Sébastien Le Floch, Haute-Ecole ARC Switzerland, Reviewer
• Dominique Leduc, Université de Nantes, Reviewer