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Visible>IR converter for phone flash

  [vote for,

So. I have a smartphone, and it is indeed smart.

I have bought a plug-on device called a Re, which is basically an infrared LED and some driver hardware, that plugs into the phone's connector. With this, and the associated app, I can use my phone as a fully- programmable remote control. I have endless fun changing channels on cafe TVs and other such childish pranks.

This is all well and etcetera, but it means I have to carry the Re around with me. It's very small, but it still gets forgotten, and I've already lost one.

The phone maker should, of course, build an IR LED into the phone. But they haven't.

However, my phone does have a superbright LED for use as a camera "flash" or as a torch.


What is called for is a small amount of a fluorescent compound which absorbs at one of the wavelengths of the "white" LED, and emits in the infrared. Such fluorophores exist, both as dyes and as quantum dots (which are more- or-less indestructible).

A clearish paint, or adhesive tape, could therefore be applied over the white LED. It probably doesn't need to obscure all, or even most, of the LED - so there would still be plenty of white light for normal use. But now the "flash" LED would also emit in the infrared and, with suitable apps, could act as a remote.

Would it be bright enough? Probably; Qdots (as an example) are very efficient fluorophores. What I am not sure of, though, is whether regular IR-LEDs are directional and whether the fluorescence of this pseudo-IR-LED would be directional enough.

MaxwellBuchanan, Apr 10 2013


       The part of the flash that remains visible would reveal you to be the prankster changing the channels on the cafe TVs
Vernon, Apr 10 2013

       That is a good point. On the other hand, a universal remote can be used for non-prankish purposes.
MaxwellBuchanan, Apr 11 2013

       //clearish paint, or adhesive tape// sliding cover.
(leaning towards +)
FlyingToaster, Apr 11 2013

       //sliding cover.// Yes, but that would be trick as an add-on. I figured that converting only a part of the white light to IR might be enough.
MaxwellBuchanan, Apr 11 2013

       Germanium is transparent to infra-red but not visible light. Perhaps make the cover out of this?
DenholmRicshaw, Apr 11 2013


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