Development of an optical fibers displacement sensor for applications in tiltmetry and seismology
type: Distribution
access URL: https://theses.hal.science/tel-00779335
format: HTML
issued: 2026-05-15T00:40:39.590005
modified: 2026-05-15T00:40:39.289012

test_moissonnage_selune
type: Agent

Development of an optical fibers displacement sensor for applications in tiltmetry and seismology
type: Dataset
contact point: Organization
  fn: CCSD
keyword: seismometer
keyword: kalman-filter
keyword: sismometre
keyword: theses
keyword: seismic-observations
keyword: interferometrie-laser
keyword: ellipse-fitting
keyword: synchronous-homodyne-demodulation
keyword: derive-lente
keyword: infoeu-reposemanticsdoctoralthesis
keyword: differential-measurements
keyword: observations-sismiques
keyword: slow-drift
keyword: mesure-differentielle
keyword: demodulation-homodyne-synchrone
keyword: temperature-compensation
keyword: modulation-de-longueur-donde
keyword: sdustugpsciences-of-the-universe-physicsearth-sciencesgeophysics-physicsgeo-ph
keyword: wavelength-modulation
keyword: laser-interferometry
keyword: lissage-dellipse
keyword: inclinometre-de-forage
keyword: borehole-tiltmeter
keyword: pendule-simple
keyword: compensation-de-temperature
keyword: filtre-de-kalman
keyword: physphysphys-geo-phphysics-physicsphysics-physicsgeophysics-physicsgeo-ph
keyword: simple-pendulum
landing page: https://theses.hal.science/tel-00779335
description: Monitoring crustal deformation during the interseismic phase when searching for earth transients requires precise instruments able to operate for very long periods. The ANR-LINES project aimed to develop three new instruments: a single-axis seismometer, a hydrostatic long base tiltmeter and a borehole pendulum tiltmeter. These three instruments benefit of an extrinsic Fabry-Pérot interferometer (EFFPI) with long optic fibers for displacement detections. Their mechanical architectures and their disposal of long fibers help these newly manufactured geophysical instruments complete their goals. The first objective of this study is to propose appropriate methods for estimating the phase of the optical path in the Fabry-Pérot cavities. A modulation of the laser diode current, followed by a homodyne demodulation of the interference signal and a Kalman filter, allow determining the phase in real time. The results are convincingwhile taking short periods measurements but require additional solutions for protection against environmental phenomena variations. The EFFPI sensor integrated in the LINES borehole tiltmeter gives it the opportunity to establish a differential measurement of the bob's oscillation thanks to three Fabry-Perot cavities. The LINES seismometer also uses the EFFPI displacement sensor to measure its coil's displacement. A description of the two instruments' mechanical structures and an analysis of the detected phenomena (slow movements, tides, earthquakes, microseisms . . . ) are part of this thesis.
issued: 2026-05-15T00:40:39.369628
language: fr
modified: 2026-05-15T00:40:39.369633