Military night vision goggles are used usually to as artificial illumination during military operations and night time combat. This adds to the safety of military personnel a lot, as they can move around without being detected by their illumination tools.
The military uses two main types of night vision goggles:
Image Intensifiers
Image intensifiers work by magnifying existing light (enemy flashlight, moonlight, starlight) so that you can see like you would during the day. But, the problem is that when a very bright light source appears, your image is overwhelmed. Their advantages are the small weight, the price, size and the detailed images they bring, while consuming little power.
Infrared Lenses
Infrared lenses convert the infrared spectrum into visible light, but at the cost of the detail, which is low. You also have problems distinguishing between two objects that have the same heat level (making it a problem finding out which is enemy and which is friend). In some cases, infrared night vision goggles can be used to see through walls.
Because they don’t need ambient light they have the advantage that they will work in any condition, just by using the heat of objects.
A Global Security survey says that these are the downsides of all night vision goggles:
– 20/25 to 20/40 vision in the best case scenario
– Monocular or tunnel vision (no peripheral vision so you need to keep looking around to see potential dangers)
– At the same distance, larger objects seem to be closer than small ones
– The time it takes you to readjust your eyes when you take off the goggles.