Sunday, November 20, 2011

Technology in Night Vision Binoculars

Let's talk about a different technology today. I chose Binoculars and more importantly night vision binoculars and the technology behind the two types of night vision binoculars viz. thermal and image enhancement. Image enhancement Binoculars detect tiny visible light radiations and amplify them for the viewer to see. The light radiation coming from the source goes through a polarizer and is then cast on to a photo tube. This photo tube then amplifies the signal up to 15000 times and then it is emitted from the other end through a lens onto a phosphorus screen. The incident radiation causes the screen to glow and emit visible green light. The image thus created can be viewed by the user. These Binoculars are cheaper and easier to use as compared to thermal imagers. One big disadvantage is that it needs at least slight amount of visible light to be present. Thermal night vision uses a completely different technology. Instead of visible night, the thermal Binoculars detect infrared radiation coming from the source and show a thermal map to the user. Every object (even the apparently cold earth) emits infrared rays which are directly proportional to the heat content of the object. Objects like animals and human beings are considerably hotter compared to background objects like walls and trees and hence can be easily identified. If you want to know what a thermal image looks like, watch the predator movie. In that movie the aliens are shown to be using thermal detection technology.

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