Share Email Print
cover

Proceedings Paper

Polarimetric active imaging in dense fog
Author(s): Robert Bernier; Xiaoying Cao; Grégoire Tremblay; Gilles Roy
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Operation under degraded visual environment (DVE) presents important strategic advantages. 3D mapping has been performed under DVE and good quality images have been obtained through DVE with active imaging systems. In these applications, the presence of fog clouds degrades the quality of the remotely sensed signal or even renders the operation totally impossible. In view of making the active imaging method more robust against dense fog, the use of polarimetry is herein studied. Spherical particles typical of fog do not depolarize incident polarized light in the backscattering (180°) direction. So, in principle, there should be less dazzling caused by aerosols for active imaging systems operating using the secondary polarization. However, strong depolarization still occurs at angles close to 180°. The greater the ratio of size to wavelength, the closer to 180° will the depolarization occur. When the cloud optical depth is small, the major scattering events seen by an active camera are the single backscattering events. However, when the optical depth of the cloud is higher than 1, multiple scattering becomes more important and causes depolarization due to the backscattering around 180°. The physics of this process will be discussed. Experimental results supporting the analysis will be presented. Those experimental results were obtained under controlled environment using the DRDC-Valcartier aerosol chamber. The experimental method herein proposed is based upon the use of ICCD range gated cameras wherein gate width and gate location may be varied on the fly. The optimal conditions for the use of these devices in view of obtaining the best image contrast are experimentally studied and reported in this paper.

Paper Details

Date Published: 8 October 2015
PDF: 10 pages
Proc. SPIE 9641, Optics in Atmospheric Propagation and Adaptive Systems XVIII, 964108 (8 October 2015); doi: 10.1117/12.2194876
Show Author Affiliations
Robert Bernier, Les Instruments Optiques du St-Laurent Inc. (Canada)
Xiaoying Cao, Lidar Consultant (Canada)
Grégoire Tremblay, AEREX Avionic Inc. (Canada)
Gilles Roy, Defence Research and Development Canada (Canada)


Published in SPIE Proceedings Vol. 9641:
Optics in Atmospheric Propagation and Adaptive Systems XVIII
Karin U. Stein; John D. Gonglewski, Editor(s)

© SPIE. Terms of Use
Back to Top