See Infrared with a TV Remote | Try it Yourself!

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In summary, someone was able to see infrared light with a remote control by adjusting their eyes to the dark and then pressing a button. This was done by playing around with different remotes and finding one with a brown filter before the LED. This made it easier to see the light because the wavelength of the IR light is around 850 nm. Playing with IR like this is dangerous because human eyes are not sensitive to it and can do lots of damage. However, if someone can see IR, it is considered visible light and therefore can be seen by people.
  • #1
waht
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I went into a dark room with a tv remote control. Then I waited a couple of minutes until my eyes adjusted to the dark. Then I pressed a button on the remote and I could see a very faint flickering brownish glow eminating from the IR LED.

I'm assuming this was just a sub-harmonic frequency generated by the non-linear characteristic of a diode, and it just happened to fall in the border of visible light.

Anyway, this was very neat. You guys can try it.
 
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  • #2
Not a sub-harmonic -- that would be non-physical for the diode. You're seeing the tail in the near-IR. Pretty cool.
 
  • #3
There was a thread in General discussion about how to see IR a while ago.
 
  • #4
After reading the thread about someone's son being able to see infrared light, I mentioned to my optoelectronics professor that some people can actually see a little of the IR spectrum. He looked at me like I was an idiot...lol
 
  • #5
leright said:
After reading the thread about someone's son being able to see infrared light, I mentioned to my optoelectronics professor that some people can actually see a little of the IR spectrum. He looked at me like I was an idiot...lol
Sounds like a good opportunity to put him in your pocket (if you're so inclined). Take a hard copy plus some of your own work to his next office hours.
 
  • #6
Playing with IR like that is a bit dangerous because human eyes are not sensitive to it, but it can do lots of damage. Especially when things are otherwise dark (like if you're trying to see IR).

Humans can see in the near UV, but it's usually blocked by the lens which becomes more opaque to UV as you get older. People who have their lens removed because of cateracts can see into the UV, even if they can't focus well. Also, early prosthetic lenses were UV transparent.
 
  • #7
I can clearly see the light from my remote controle. Do different remotes usually differ a lot in frequency? Maybe I just happen to have one which emitts some red light too...have to try another one.
 
  • #8
If you can see IR, isn't it then, by definition, visible light?
:)
 
  • #9
Sometimes I watch radio. But it's in black and white.
 
  • #10
EL said:
I can clearly see the light from my remote controle. Do different remotes usually differ a lot in frequency? Maybe I just happen to have one which emitts some red light too...have to try another one.
Yes. Some emit red light.

It was https://www.physicsforums.com/showthread.php?t=134077"and I had a control on the test. I could not see the light at all, whereas he could see it quite clearly.
 
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  • #11
Euclid said:
If you can see IR, isn't it then, by definition, visible light?
:)
Well, no. I mean, IR is not defined individually by each person. (Does a blind person count the entire spectrum as IR?)
IR is a specific range of freqs, though it is true that it has a "fuzzy border" with visible light.
 
  • #12
NateTG said:
Playing with IR like that is a bit dangerous because human eyes are not sensitive to it, but it can do lots of damage. Especially when things are otherwise dark (like if you're trying to see IR).

I specifically chose a remote control because it's a convenient source of low power infrared radiation, it's probably less than 1 mW power output, and IR is not ionizing like UV. Besides, a daily IR dose from sun is much greater, even when pupils are dilated.

I thought about evolution for a little bit. Since every offspring has a little different genes from parents because of random mutations (to increase the chances for survival) it makes sense that a small subset of population would develop a greater sensitivity to infrared and others to UV.
 
  • #13
DaveC426913 said:
Yes. Some emit red light.

It was https://www.physicsforums.com/showthread.php?t=134077"and I had a control on the test. I could not see the light at all, whereas he could see it quite clearly.


I can confirm it. Your son was right.

If your remote has a brown filter before the LED, than it would be harder to see then glow.

I tried a couple of different remotes that have the LED sticking out and they all glowed with same intensitiy. The standard wavelength of these diode is about 850 nm.

I'm going to try and get a hold of various IR leds with different wavelength and see which one I can see.
 
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  • #14
waht said:
If your remote has a brown filter before the LED, than it would be harder to see then glow.
Well yes. But the discrepancy was marked. I looked and looked and looked and looked and saw nothing at all. He made the right call every single time without the slightest hesitation. I clicked and clicked and clicked the button, trying to throw him off, and he might as well have been looking at a flashlight.

waht said:
I tried a couple of different remotes that have the LED sticking out and they all glowed with same intensitiy. The standard wavelength of these diode is about 850 nm.
Really? Good to know. I had just assumed that they'd all be different. But you're right, they wouldn't be, would they?
Here's http://en.wikipedia.org/wiki/Image:Control-remote-spectrum.png" that shows it peaks just shy of 950nm.

So, what is the average for humans?

Looks like about 700nm. So my kid can see all the way down to 850?
According to http://www.sjsu.edu/faculty/watkins/eye.htm", he's off the charts!
 
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  • #15
Does it change if you wear glasses? Can you see it?
 
  • #16
DaxInvader said:
Does it change if you wear glasses? Can you see it?
What do glasses have to do with it? It's 6 inches in front of my face!


P.S. Just to prove to myself I wasn't completely insane, I decided to see what my video cam saw. My video cam detects the LED like it's a searchlight!
 
  • #17
Some glasses has some protection layers.. Anti-reflections.. Or other stuff like it.. Its already hard seeing it with a naked eye.. Just asking the question.
 
  • #18
OIC.

No. No effect.
 
  • #19
Thanks then :P
 

Related to See Infrared with a TV Remote | Try it Yourself!

1. How does a TV remote allow us to see infrared light?

The infrared (IR) light emitted by a TV remote is not visible to the naked eye. However, most digital cameras, including those on smartphones, are able to detect IR light. When you press a button on a TV remote, it emits a series of IR signals, which the camera picks up and displays on the screen as a visible flash of light.

2. Can any camera detect IR light?

Most digital cameras, including those on smartphones, are able to detect IR light. However, some cameras have IR filters that block out IR light, making it impossible to see the flashes from a TV remote. To test if your camera can detect IR light, simply point a TV remote at the camera and press a button. If you see a flash of light on the camera's screen, it can detect IR light.

3. Are there any other objects that emit IR light that can be detected with a TV remote?

Yes, there are many objects that emit IR light, such as heat sources, light bulbs, and even our own bodies. However, a TV remote emits a specific pattern of IR signals that can be easily distinguished from other sources of IR light. This is why it is commonly used to demonstrate the detection of IR light.

4. Is it harmful to view IR light with a TV remote?

No, it is not harmful to view IR light with a TV remote. The IR light emitted by a TV remote is very low in intensity and does not pose any health risks. However, it is important to avoid looking directly into the IR emitter on the remote, as it may cause eye strain or discomfort.

5. Can I use a TV remote to see through objects or walls?

No, a TV remote cannot see through objects or walls. While IR light can pass through certain materials, such as thin fabrics, it cannot penetrate solid objects. The flashes of light you see on a camera's screen when using a TV remote are simply reflections of the IR light off of objects in the room.

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