True-color night vision cameras

Abstract

This paper describes True-Color Night Vision cameras that are sensitive to the visible to near-infrared (V-NIR) portion of the spectrum allowing for the "true-color" of scenes and objects to be displayed and recorded under low-light-level conditions. As compared to traditional monochrome (gray or green) night vision imagery, color imagery has increased information content and has proven to enable better situational awareness, faster response time, and more accurate target identification. Urban combat environments, where rapid situational awareness is vital, and marine operations, where there is inherent information in the color of markings and lights, are example applications that can benefit from True-Color Night Vision technology. Two different prototype cameras, employing two different true-color night vision technological approaches, are described and compared in this paper. One camera uses a fast-switching liquid crystal filter in front of a custom Gen-III image intensified camera, and the second camera is based around an EMCCD sensor with a mosaic filter applied directly to the sensor. In addition to visible light, both cameras utilize NIR to (1) increase the signal and (2) enable the viewing of laser aiming devices. The performance of the true-color cameras, along with the performance of standard (monochrome) night vision cameras, are reported and compared under various operating conditions in the lab and the field. In addition to subjective criterion, figures of merit designed specifically for the objective assessment of such cameras are used in this analysis.