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I was making a tutorial on a Wii video game. I didn't know where my camera was, so I used my webcam. The sensor bar is wireless and is a very inefficent make, so when I showed it to the camera I noticed that there were lot more LED dots than there should be. There was the normal blue one in the center, and the two ones that cannot be seen unless scrutinized real close (the light is a weird shade of red). However to the camera it looks like white LEDs. I understand how it could detect a strong source of light, but why does it convert it to visible light? I tried this with my TV remote too and the same thing happens! I should try it with other things too. But my question is... why does it detect it if we don't need to see it and why does it display it in the visible light spectrum as white light?
*to the mods: for once i actually have a legit post. see? I'm getting better.*
Registered Member #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
The camera's DO have IR filters. What you're seeing is what little bit of light that gets through the filter. They can't get rid of all of it unfortunately, as I think it would get rid of part of the red spectrum as well, making it seem washed out towards more red colors. You can see the same effect in other cameras too, like cell phones and normal digital cameras as well.
You can make cameras detect ir a lot ...better, I guess, by removing the IR filter. That way you can make night vision goggles or something!
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
to answer the other part of your q : IR shows as white on a web cam as the red, green and blue pixel filters all let IR through. At work we have made an IR passing daylight filter simply by laminating red and blue plastic film together - result looks black to the eye, but IR goes straight through.
Silicon camera chips will detect IR as long as 1100nm, at which point silicon becomes transparent to longer wavelengths. The LEDs you are seeing are probably 850nm - in a dark room you will be able to make out a faint red glow, but don't look too close as those LEDs are WAY brighter than they appear and there is potential for eye damage with some powerful IR LEDs ( no pupil or blink response to save your retina ).
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My webcam can see IR... why?
