How to get 2.8v OUT of a LED.

[hydguy]

Hey all, I was reading this post http://laserpointerforums.com/f38/list-all-known-uv-fluorescent-material-43167.html and saw that led's floures under 405mn. light. So I had to try it. Yup, sure enough, it does, bright too @ 570ma. So i was :thinking: I should hook my meter to the LED. I set it to mv. turned the laser on and my meter went from 0.00 to OFL.:huh: This cant be rite...So I set the meter to DCV, turned laser on and 2.8vdc. At this point I'm thinking is it only the 405mn or will 445mn do this too? Yup a watt of 445 works too. Next in this experiment I connected another LED to the one I was lighting up with the laser, turned on the 405mn and the LED lit up from the 2.8v produced by the lased LED. Then I put my DX 200mw. 532nm on it and NOTHING:wtf: Now the LED's I used were blue, this may be why the green didnt work. So if anyone has a green LED with a clear dome try this with a green laser and let me know if you get any voltage out. I guess we could try a red too if someone had one on hand.
Is this something new or am I just behind the ball here?
Could I use a test load to measure mw out of the LED?
Any how just sharing some findings...

 

[Things]

LED's are well known to produce a small amount of power when you shine light at them, they are even used as photo detectors in some devices.

The power they output is nothing, however, you may just be able to power another LED with it.

 

[RA_pierce]

If you shine 445nm onto the emitter of a white LED it will glow a very brilliant white.

 

[hydguy]

@ Things, Why no output with the green laser?

 

[Leodahsan]

because the led have a low absorptive die - hence only the high powered radiations (near UV) will be absorbed enough to get a significative sign of power

just like the GITD things, I'm sure a PURE UV led would make the led output ~4v

 

[Things]

For a green laser to produce any output on a LED, you need a green LED. You have to somewhat match the wavelengths.

 

[Pontiacg5]

Shining a laser on a LED used to be used as a "ghetto" laser power meter. There were a few equations that would give you a relative power figure based on the voltage the laser would produce across the LED.

Just a fun fact from the wayback Laser days. A personal LPM was unheard of 5 years ago...

 

[Cyparagon]

you may just be able to power another LED with it.

Yup - it works. It's dim though.