Design Considerations For Night Vision Goggles

Abstract

Baird Corporation of Bedford, Massachusetts, has designed and developed two similar night vision goggles. These goggles are binocular viewing to the wearer's eyes, but use a single objective lens and a single image intensifier tube. Binocular viewing is achieved by dividing a single image and sharing it between the'viewer's eyes. The goggles are self-sufficient, independent instruments which can be simply and easily interfaced with a face mask that the viewer wears. This paper covers the main design considerations that are associated with achieving the goals of these goggle configurations and their performance. Baird's first goggle design is designated the GP/NVG; the second is designated the AN/PVS-7. The GP/NVG night vision goggle is a high-performance, single intensifier tube, passive night vision device that provides the user with a 40-degree field of view at unity magnification. The fixed aperture, f/1.0 objective lens collects the available light and images it on the fiber optic faceplate of the second generation image intensifier tube. The image intensifier tube converts the real image at the fiber optic faceplate into electrons across the image, amplifies them, and then reconverts the electrons into a real, visible image at the fiber optic output of the tube. This image is then collimated to appear as if it is coming from infinity, split in two, and reimaged by the relay lenses. The eyelenses provide a magnified image to the user. The user can adjust each eyelens to clearly view the output faceplate of the image intensifier tube. This adjustment is made only once for each user. The objective focus can be manually set for distances from 25 centimeters to infinity. The general configuration of this night vision goggle is similar to that of a pair of single objective binocular field glasses. It is extremely lightweight (with most of the main construction molded from plastic) and compact for easy handling. All adjustments and on/off switching have been "human" engineered for ease of operation. To meet the requirements of the U.S. Army, Baird is now developing the AN/PVS-7 goggle. The most significant difference from the GP/NVG goggle is the use of a third generation image intensifier tube in the AN/PVS-7 goggle. Other changes have also been made, but the general design is the same for both.