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Laser went dim...

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So, a week or two after making my first semi respectable burning laser (here), for some reason last night it suddenly dropped to less than half its original power..

I can't think of what might have caused this, I've been running it on a short(ish) duty cycle, turning it off for a couple minutes any time it starts to get warm.. I've checked the battery, it's still at 7.4v, I've checked the voltage and current going to the diode, 3.1v @ 351mA for my short open can... all completely within spec, yet it's now the brightness of maybe a 10mW... Anyone know what could cause that? It was on when it did it, and I wasn't touching it at the time, it just massively dropped in brightness, spontaneously and for no reason.
 

chido

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350mA is pushing these short open cans a lot. I wouldn't be surprised if it's dead. So far I've been driving mine at 250mA with great results, it has a total runtime of 9 hours 5 minutes and still going strong. ;D

Check out Dr. Lava's graph of my short open can:



EDIT: I saw you say it looks like a 10mW laser, are you sure? Doesn't it look like an LED? If it's brighter than a 5mW laser then there's still hope.
 
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:-/

yeah, it's not all that bright... of course it still lases and colminates properly.. and I can easily see the dot 20 feet away in a well lit room.. I'd say it's as bright as a 5mw, but I have no 5mws to compare it to..

So you think it's dead eh? Nuts.
Oh well, I've been meaning to take apart this 18x LG for a while now, this gives me an excuse to do it...
 

flogged

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350mA ?? Dude, you need better heatsink. I feel sorry for your diode, you cooked it. The lifespan of these LD's decreases exponentially with temperature.

Look at the graph above. 350 mA is probably too much current, at least if you want a reasonable lifespan for the diode.
 

chido

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Could you post a pic of the dot? I'm almost sure it's dead but there's still hope.
 

Eudaimonium

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I say it's dead. Hate to burst your bubble, but if the diode seems to shine like an red LED it's totally dead.
Take it from me, I've destroyed a dosen of laser diodes (please dont ban me!!!)
and if the power seems 1/20 of previous power, and no burning, it's totally dead. I am deaply sorry for your diode :(
But, now you have an excuse for destroying 18x fryier :D
I just want to point out, double-check your circuitry 10 times for the possibility of a short, if your driver has any capacitros on parallel with diode,
any short after the switch will kill it.
 

Xylicon

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I'd say you cooked it, I just accidentally put 1.3A through one of my diodes and its now maybe at best 5mW output.

Don't ask how it happened :-[
 

brtaman

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My novice opinion is that you indeed cooked it, on a side note anyone know of a store (preferably EU, selling broken 20x DVD burners, would be pretty cool...)


(sorry for the random post, I want to build up to 10 posts so that I can pm drlava about the flexdrive.)

Thanks
brtaman
 




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