Skip to Main content Skip to Navigation
Theses

Imagerie laser à synthèse d'ouverture par réinjection optique

Abstract : We present in this PhD thesis a technique of synthetic aperture laser imaging. The basic imager, called Laser Optical Feedback Imaging (LOFI) detects the weak frequency-shifted optical feedback retrodiffused by the target, which is amplified by the laser dynamics. The great advantage of this technique is its self-alignment, i.e. the laser is the source and the detector. The spatial resolution of the images LOFI is diffraction-limited : we propose to adapt the technique of synthetic aperture, well known in radar to overcome this problem. Using the scanning of the laser on the target required to form the image pixel by pixel, we show that it is possible to increase the collection aperture of the system, hence the resolution. We present the signal processing aimed at the reconstruction of the super-resolved image from the history datas along the direction of motion. We show that it is possible to extend the technique using a linear scanning, to an angular scanning and that we can obtain a resolution not even better than the diffraction limit, but also better than the resolution reachable with a linear scanning. We illustrate this technique with experimental results that compare the images LOFI with and without synthetic aperture operation.
Then, we present the parametric working of the LOFI device subject to a pump modulation. We present the analysis of a laser subject to a synchronized frequency-shifted optical feedback and a pump modulation and we show that it is possible to have parametric amplification of the weak feedback from the target. We illustrate this analysis with numerical and experimental results and we demonstrate that it is possible to determinate the amount of light retrodiffused in the laser.
Complete list of metadata

Cited literature [18 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00144904
Contributor : Arnaud Witomski <>
Submitted on : Monday, May 7, 2007 - 10:02:36 AM
Last modification on : Tuesday, September 11, 2018 - 11:00:02 AM
Long-term archiving on: : Wednesday, April 7, 2010 - 2:14:19 AM

Identifiers

  • HAL Id : tel-00144904, version 1

Collections

UJF | UGA | CNRS | LIPHY

Citation

Arnaud Witomski. Imagerie laser à synthèse d'ouverture par réinjection optique. Physique Atomique [physics.atom-ph]. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00144904⟩

Share

Metrics

Record views

241

Files downloads

674