Image tube performance evaluation is usually presented in terms of scene resolution and contrast capabilities. The extension of these image concepts to small target detection configurations that occur in military applications is not immediately evident.
The purpose of this paper is to: (a) propose criteria for evaluating the minimum detectable increments in radiant power arriving from small targets; and (b) described a laboratory test procedure for implementing the foregoing evaluation. The procedure is based on system response to a unit spatial-impulse input. The minimum detectable input power differences for a system utilizing a uniform film image tube as a sensor are a function of the angular extent of the target as measured from the optics. The minimum detectable increment in response density is considered to be a fundamental system parameter to be determined. The peak response density is related to the input density through a response-degradation curve.
The method was developed for use with the Westinghouse Thermicon and is being applied to the evaluation of preliminary models of that infrared image tube. It is fully applicable, however, to any other uniform film image tube.
© 1959 Optical Society of AmericaFull Article | PDF Article