Share Email Print

Proceedings Paper

Use of polarization to improve signal to clutter ratio in an outdoor active imaging system
Author(s): Patrick F. Fontoura; Michael K. Giles; Denise D. Padilla
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

This paper describes the methodology and presents the results of the design of a polarization-sensitive system used to increase the signal-to-clutter ratio in a robust outdoor structured lighting sensor that uses standard CCD camera technology. This lighting sensor is intended to be used on an autonomous vehicle, looking down to the ground and horizontal to obstacles in an 8 foot range. The kinds of surfaces to be imaged are natural and man-made, such as asphalt, concrete, dirt and grass. The main problem for an outdoor eye-safe laser imaging system is that the reflected energy from background clutter tends to be brighter than the reflected laser energy. A narrow-band optical filter does not reduce significantly the background clutter in bright sunlight, and problems also occur when the surface is highly absorptive, like asphalt. Therefore, most of applications are limited to indoor and controlled outdoor conditions. A series of measurements was made for each of the materials studied in order to find the best configuration for the polarizing system and also to find out the potential improvement in the signal-to-clutter ratio (STC). This process was divided into three parts: characterization of the reflected sunlight, characterization of the reflected laser light, and measurement of the improvement in the STC. The results show that by using polarization properties it is possible to design an optical system that is able to increase the signal-to-clutter ratio from approximately 30% to 100% in the imaging system, depending on the kind of surface and on the incidence angle of the sunlight. The technique was also analyzed for indoor use, with the background clutter being the room illumination. For this specific case, polarization did not improve the signal-to-clutter ratio.

Paper Details

Date Published: 18 August 2005
PDF: 7 pages
Proc. SPIE 5888, Polarization Science and Remote Sensing II, 58880B (18 August 2005); doi: 10.1117/12.619572
Show Author Affiliations
Patrick F. Fontoura, New Mexico State Univ. (United States)
Michael K. Giles, New Mexico State Univ. (United States)
Denise D. Padilla, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 5888:
Polarization Science and Remote Sensing II
Joseph A. Shaw; J. Scott Tyo, Editor(s)

© SPIE. Terms of Use
Back to Top