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Comment by sengork | Hacker News Reader

Thanks this is the first time I have come across https://en.wikipedia.org/wiki/Yokogawa_Electric

Also it's refreshing to see that they mention "seeing" IR light from a remote control via your mobile phone's camera. This trick has been around for years (thanks to cameras tendency to colour shift) however it is rarely known about. The author is indeed a practitioner.

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Modern phones don't see IR very well on account of improved filters. My iPhone can't see remotes at all. An IR source needs to be much more powerful to show up.

Back in the day I took the IR filter out of my digital camera and got some cool (dismal 3.2MP resolution) shots.

The rear camera has a very strong IR blocking filter. But the front camera doesn't. (We have a product that uses IR LEDs as a flash, and I use my front-facing camera to verify they're working.)

Thanks for this! Works on iphone 6

I just tried this with my phone and mildly blew my mind, and then realized I could actually see the IR from the remote with my eyes, and am now confused.

He mentioned it in the presentation. You're not actually seeing the IR, you're seeing a sideband. Just like with a heat lamp, the red light isn't the IR, it's produced alongside the IR.

If its a 808nm or other really close wavelength, then you could be seeing the primary wavelength, but the apparent intensity will be very low as the eye has very little sensitivity.

The effect is even more pronounced when you remove the IR filter.

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