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I try to understand how is possible to turn a photo receptive sensor into an emitter of light.
Settings, tools, modulation..

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    $\begingroup$ Not all processes used in such sensors are reversible. Do you have a particular sensor technology in mind? Otherwise, this question is far too broad. $\endgroup$ – Dave Tweed Dec 15 '16 at 1:29
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In the general case, you can't. Not all processes are reversible. For example, a Cadmium-sulfide photoresistor won't emit light when you apply a voltage to it.

There really shouldn't be the expectation that this would work in general since there are so many every day examples. Your car doesn't put gas back into the tank when going down a hill. You don't get less hungry by walking down a mountain. Etc, etc, etc.

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  • $\begingroup$ Can you tell me an working example, instead ? In general case but not in all case, right ? Cadmium-sulfide are not reversible but there are some material reversible if you apply a voltage (or use some properties, spin, quantum..) Can you tell me if there are a working example ? Thanks $\endgroup$ – Jacky Ned Dec 16 '16 at 13:10
  • $\begingroup$ @Jack: A LED does work in reverse somewhat. It emits light when forward current is applied. However, it also works like a photocell or a photodiode when you shine light on it. It's not as efficient as a photocell or photodiode designed to exploit that effect, but it can be usable with the right circuit. $\endgroup$ – Olin Lathrop Dec 16 '16 at 13:17

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