Athermalization of infra-red camera of projectile weapons

One of the vital components of projectile weapons is Infra-Red Camera (IRC) which detects target by virtue of Infra-Red imaging. The lenses of IRC are designed to operate at a temperature of (+)30 degrees C +/- 1 degrees C. When these weapons were fired from Siachen glacier region, where temperature is around (-)20 degrees C, they posed the problem of missing their targets. Similar problem was encountered while firing from Thar desert region, where temperature is around (+)60 degrees C. Hence, the optical lens of IRC is required to be brought from the prevailing ambient temperature of (+)60 degrees C or (-)20 degrees C to (+)30 degrees C +/- 1 degrees C within a very short span, say 60 s to render it suitable for military applications. The objective of this paper is to outline novel mechanism by which uniform temperature of (+)30 degrees C +/- 1 degrees C from the ambient temperature of (-)20 degrees C or (+)60 degrees C can be achieved within 60 s using thermoelectric heating/cooling devices acting as heat pumps. It was found that two of the lenses made of germanium attained the temperature of (+)30 degrees C +/- 1 degrees C much before 60 s, while the third lens made of AMTIR-1 did not attain the required temperature in stipulated time. (C) 2008 Elsevier Ltd. All rights reserved.