Image Intensifier
From Night Vision Wiki
An image intensifier is an electro-optical component that can produce an intensified image from a cone of incoming light, usually intended to enhance an incoming image beyond what optics and digital sensors are usually capable of.
In the field of night vision, image intensifier tubes are miniaturized image intensifiers, usually in tubular shape, that are inserted into a housing that only provides protection, optics and power supply. Many formats of image intensifier tubes are designed to be exchangable with limited tooling and know-how, originally intended to allow armies to replace damaged image intensifier tubes by a trained engineer on location.