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Author Topic: Night Vision Goggles! How do they work??  (Read 2891 times)

Offline Seany

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Night Vision Goggles! How do they work??
« on: 17/05/2007 18:49:23 »
Apparently, you need a tiny tiny tiny source of light, such as the moon, or even a smaller source of light. But with this little amount of light, how does this goggle work? And why does it look green?


 


Offline Seany

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Night Vision Goggles! How do they work??
« Reply #2 on: 17/05/2007 20:58:10 »
Hmm thanks. But how does it amplify the light?
 

another_someone

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Night Vision Goggles! How do they work??
« Reply #3 on: 17/05/2007 21:39:23 »
In all cases, light is not directly amplified, but converted into an electrical signal of some kind, and amplified as an electrical signal.

There are different ways of doing this, but in all cases, the amplification is done at the electrical level.

It might theoretically be possible to directly amplify light using lasers, but I am not sure that with todays technology, that would achieve much, since I would imagine that current lasers are not sensitive enough to low light levels, and in any case we have not yet developed arrays of lasers that would allow amplification of an entire image.

Dave Shorts mentioned two ways of amplifying light(http://www.thenakedscientists.com/forum/index.php?topic=2376.msg18922#msg18922), but I think I have heard of a third, which also uses phosphors, but rather than accelerating the electrons with a voltage, sends the electrons down an array of tubes that bounce about inside the tubes, causing other electrons to be knocked off the sides of the tubes, so one electron entering the tube can create a cascade of electrons down the other end of the tube.
 

Offline JimBob

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Night Vision Goggles! How do they work??
« Reply #4 on: 18/05/2007 01:42:36 »
You would not need them if you eat your carrots. Its a vitamin thing.

Actually humans see fairly well at night IF they get their night vision. This takes at about an hour. It also takes a dark night without light pollution from civilization. Several years ago the yearly Leonid meteor shower was forecast to be spectacular at about 3 AM local time when the earth passed through the thick center of the meteor cloud that forms this yearly phenomenon. I took my dog, drove 60 miles into the deserted countryside of large ranches and lay down in the back of my pick up (a cowboy Cadillac). after about an hour I could see almost as well as I could in the daytime. The only light was starlight. This just recalled what it was like when the house I grew-up in was at the edge of the city.

As we - mankind - have become more civilized we have lost most of our links with nature. I think not having a starry night is one of the worst deprivations mankind is subjected to. There is an unequaled sense of awe and smallness associated in my mind with a moonless starry night with ever square inch of the night covered with half a million stars - litteraly.

'Awe' is an experience everyone should have.

« Last Edit: 18/05/2007 01:44:21 by JimBob »
 

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Night Vision Goggles! How do they work??
« Reply #4 on: 18/05/2007 01:42:36 »

 

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