Image Intensification
The Army’s Image Intensification program grew out of the near infrared imaging tube development activity. During 1955 – 1958, in-house systems analyses and visual human factor studies resulted in the development of techniques permitting the prediction of detection and target recognition performance of electro-visual devices in general. These studies continued to indicate that cascade image tubes and intensifier image orthicons were the most promising intensifiers for military use.
After a profound effort on the part of industry and staff members of the Night Vision and Electronic Sensors Directorate, the development of the first generation imaging tube was completed by early 1965 and the production phase initiated. This resulted in the availability of passive night vision systems in the Southeast Asia Theatre.
The first-generation image intensifier devices represented a major advance in night vision military technology: A soldier could now conduct his combat missions without any active illumination sources using only image intensifiers.
Image intensifiers capture ambient light and amplify it thousands of times electronically to display the battlefield to a soldier via a phosphor display such as night vision goggles. This ambient light comes from the stars, moon or sky glow from distant manmade sources, such as cities.
The image, below, illustrates the process whereby an image intensifier system amplifies a low level input image with spatial coherence and displays a high level output to the observer. The system consists of a front-end objective, an image intensifier tube and a display eyepiece.
Intensifier Tube
The dim image is focused on the photocathode of the image intensifier tube which consists of 3 single-stage image-converter tubes each fiber optically coupled to each other. The photo-electronic image is accelerated by an electric field. The resulting electron energy is transferred to a luminescent screen and converted to light. The process is repeated in the second and third stages increasing the light gain resulting in a resolution which can vary between 20 and 23 line pairs/mm.
The first-generation family of night vision devices consisted of three systems: the following
- The Starlight Telescope
- Crew Served Weapon Sight
- Night Observation Device
