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Photo Diodes?

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What do Photo Diodes do? What will happen if i connect a pin to the PD?
 

Things

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You will probably see a tiny amount of somoke, followed by a very hot diode which wll burn your hands, and screw it up completely.


Sounds nice doesnt it? ::) ::)
 

MarioMaster

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photodiode is only for optical feedback of the laser output (a lot of diodes don't even have one even though they have a pin for it)
 

Book

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Isn't a photodiode a device for detecting/measuring light? At least that's what wikipedia says.
 

Zom-B

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Just as MM sais.

A photodiode converts some photons to electricity. The brighter the laser diode is, the higher the voltage is on the PD pin. Don't expect to run a light bulb on this voltage because it is only enough for electronic measurements. Typical 5mW laser pointers will try to put just enough current to the laser diode such that the measured brightness is constant, even when the batteries are dying. There is a way to test thi: when you shine a laser pointer in the lens with another laser pointer, it will lose brightness because the driver thinks there is too much light.
 

Book

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Ah, so every laser contains a photodiode inside, to keep it from delivering low brightness light when the batteries are dying?
 

Ace82

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I thought they were used to govern the lasers intensity for both high and low. :-? (this question has been raised a few separate occasions around here with no definite result (except for dx lasers don't need them although some have them), at least to the best of my knowledge).
 

chido

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I know, maybe some day in the future the photo diode could be connected up to a circuit with a display so you could know exactly how many mW the laser would be putting out every time you turned it on. :eek:
 

chido

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You would need to reflect tiny part of the beam back to the photo diode and have the circuit calculate the power of the entire beam. (I think)
 




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