Night vision goggles are the collective name for the optical devices in the form of wearable glasses, goggles, binoculars as well as telescopes, for the purpose of seeing objects in the darkness. Night vision goggles are widely used by armed forces, rescue teams, property security, local law-enforcement and even for fun by hobbyists.
Night vision goggles can be categorized as active and passive systems. The active night vision goggles cast infrared light to an area enabling the wearer see the objects in that area at night. The passive night vision goggles gathers the very dim light from nearby and amplify the image signals via electronic systems so that the viewers can identify things from the screen.
It is believed that there are 4 generations of night vision goggle till now. The first generation is called generation 0, which are the active infrared goggles. These night vision goggles were first used by US Army in WWII. Later Germany developed the same night vision goggles which were outfitted in Nazi forces. As these active night vision goggles can be easily seen by enemies, they were gradually phased out in the Vietnam War.
Gen 1 is the first ever passive type of night vision goggle, which were first used in the battle field of Vietnam War. By adapting old technology and using new intensifier with light amplification of 1000x. Gen 1 gets rid of the active infrared, but still need pretty strong moonlight to aid to see the objects. Gen 2 night vision goggle further use new technology such as micro-channel plate to achieve much clearer image resolution even in pitch darkness. The light amplification reached 20000x. Gen3 even further increase the visibility, image resolution and image reliability, and achieved 30000-50000x light amplification.
One sub-model from Gen 3 worth mentioning is Omnibus-VII. Night vision goggles in Omnibus-VII use the new out-gating technology enabling the night vision goggle change as fast as light changes, and can retain the stable visibility even when being exposed to very bright light at a sudden.