Target range of Infra-Red (IR) point target warning systems, is determined by the effective entrance pupil diameter of the system's optics. In addition, the system's F/_# is usually set by the detector (as in cryogenically cooled detectors). Moreover, the detector's aspect-ratio usually set the field proportions (5:4, 4:3, etc.).Thus for example, for wide angle systems, the horizontal coverage angle is usually determining the vertical one. We propose a system including anamorphic optics that changes the effective focal length of each axis independently, keeping the detector's given F/_#, thus changing the effective aperture. Since the range is approximately proportional to the effective aperture, we achieve a range improvement of the square-root of the vertical and horizontal focal length ratio, reducing the vertical coverage accordingly. In this way, we make the field proportions less dependent of the detector's proportions. Using this method, it is made possible for wide angle systems to improve target detection range on the expense of the vertical coverage, without changing the horizontal coverage or increasing the amount of detection units (e.g. FLIRs).

Date Published: 7 October 2014
PDF: 6 pages
Proc. SPIE 9249, Electro-Optical and Infrared Systems: Technology and Applications XI, 924902 (7 October 2014); doi: 10.1117/12.2065543

Published in SPIE Proceedings Vol. 9249:
Electro-Optical and Infrared Systems: Technology and Applications XI
David A. Huckridge; Reinhard Ebert, Editor(s)