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Proceedings Paper

A novel snapshot polarimetric imager
Author(s): Gerald Wong; Ciaran McMaster; Robert Struthers; Alistair Gorman; Peter Sinclair; Robert Lamb; Andrew R. Harvey
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Paper Abstract

Polarimetric imaging (PI) is of increasing importance in determining additional scene information beyond that of conventional images. For very long-range surveillance, image quality is degraded due to turbulence. Furthermore, the high magnification required to create images with sufficient spatial resolution suitable for object recognition and identification require long focal length optical systems. These are incompatible with the size and weight restrictions for aircraft. Techniques which allow detection and recognition of an object at the single pixel level are therefore likely to provide advance warning of approaching threats or long-range object cueing. PI is a technique that has the potential to detect object signatures at the pixel level. Early attempts to develop PI used rotating polarisers (and spectral filters) which recorded sequential polarized images from which the complete Stokes matrix could be derived. This approach has built-in latency between frames and requires accurate registration of consecutive frames to analyze real-time video of moving objects. Alternatively, multiple optical systems and cameras have been demonstrated to remove latency, but this approach increases cost and bulk of the imaging system. In our investigation we present a simplified imaging system that divides an image into two orthogonal polarimetric components which are then simultaneously projected onto a single detector array. Thus polarimetric data is recorded without latency on a single snapshot. We further show that, for pixel-level objects, the data derived from only two orthogonal states (H and V) is sufficient to increase the probability of detection whilst reducing false alarms compared to conventional unpolarised imaging.

Paper Details

Date Published: 24 October 2012
PDF: 12 pages
Proc. SPIE 8541, Electro-Optical and Infrared Systems: Technology and Applications IX, 85410G (24 October 2012); doi: 10.1117/12.974824
Show Author Affiliations
Gerald Wong, SELEX Galileo Ltd. (United Kingdom)
Ciaran McMaster, SELEX Galileo Ltd. (United Kingdom)
Robert Struthers, SELEX Galileo Ltd. (United Kingdom)
Alistair Gorman, Univ. of Glasgow (United Kingdom)
Peter Sinclair, SELEX Galileo Ltd. (United Kingdom)
Robert Lamb, SELEX Galileo Ltd. (United Kingdom)
Andrew R. Harvey, Univ. of Glasgow (United Kingdom)

Published in SPIE Proceedings Vol. 8541:
Electro-Optical and Infrared Systems: Technology and Applications IX
David A. Huckridge; Reinhard R. Ebert, Editor(s)

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