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simple diode fix for dummies pics

rhd

rhd

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I'm not intending to thread jack here, but there seem to be a number of members in this thread that are fairly knowledgeable about diode-death, and this is a semi-related question (but probably not worthy of a new thread).

When excess current kills a diode, is it the heat that causes death? Or is it the excess current itself?

The reason I ask -
I've been pushing a fairly expensive HL63133 diode past its suggested current of 250mA, and even past its max rated current of 320mA.

I'm at 375mA, and I'm still seeing fairly reasonable returns in terms of mW output. What I'm NOT seeing, is really any heat at all. This is encouraging if heat is the mechanism by which excess current kills a diode. I have a feeling though, that there's more to the story than this. I'm not looking for anyone else to make the yes/no decision as to whether I should push this further for me. However, I'd love a bit more insight. Does death result from excess current, in the absence of noticeable heat?
 





HaloBlu

HaloBlu

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Did someone ask about failure modes? :D
May I direct you to Mr. Pullbangdead for a long fun answer.
Finding max mw for an Open Can LD (Pullbangdead + Failure mode)
Feel like I might recall a nice pic (likely from Pullbangdead) of a die with its front surface blown right off.
There have also been pics of wires melted right off the die. :)
Anyone recall where one of those pics might be?
 
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Flaminpyro

Flaminpyro

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They can also die from too many photons bouncing around inside of them it's an optical over load, I don't know the correct term so I'm sure someone will pop up and give us the right discription of what happens.
So yes they can die and not from heat or over current :whistle:


rhd said:
I'm not intending to thread jack here, but there seem to be a number of members in this thread that are fairly knowledgeable about diode-death, and this is a semi-related question (but probably not worthy of a new thread).

When excess current kills a diode, is it the heat that causes death? Or is it the excess current itself?

The reason I ask -
I've been pushing a fairly expensive HL63133 diode past its suggested current of 250mA, and even past its max rated current of 320mA.

I'm at 375mA, and I'm still seeing fairly reasonable returns in terms of mW output. What I'm NOT seeing, is really any heat at all. This is encouraging if heat is the mechanism by which excess current kills a diode. I have a feeling though, that there's more to the story than this. I'm not looking for anyone else to make the yes/no decision as to whether I should push this further for me. However, I'd love a bit more insight. Does death result from excess current, in the absence of noticeable heat?
Click to expand...

@ anselem Wow a bit over the top as MFO said he didn't tie them down :crackup:
 
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HaloBlu

HaloBlu

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Oh oh, is it COD?! :evil:
I'm going with COD as the correct term. (i might have cheated off of PBD's test) :whistle:

*cough* Now whats COD stand for? Critical Optical Damage? Death? Destruction? Crapped Out Diode?:undecided:
 
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C

conundrum

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I second that, heat is normally what kills them.
I've had a 405nm 30mW diode from an Xbox HD-DVD drive which worked fine at 78mA and put out over 60mW until it failed due to the aixiz heating up.
Yes, it COD'd :-( aka Catastrophic Optical Damage.
Effectively the front facet gets broken, in fact it can be blown apart in severe cases.
Its harder to see on 405's but you can normally see a discoloration.

I've never fried a burner diode yet though, they seem to be much more robust.

-A
 
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A

anselm

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COD indeed stands for Catastrophic Optical Damage.
Sam's Laser FAQ - Diode Lasers
Heat is not the only issue.;)

Yeah I guess I overreacted at the OP, at the time the forum was filled with noobs
everyday asking for a 1W blue on their first post, and I was in one of those moods.....

Sorry try2die.
 
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try2die

try2die

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every diode lens i get start to burn a pin hole in center of cap lens, is this common with all diodes? anselm,all youre post are cool with me, everyone has there own veiws and opionions, at least you seem to be honest. thanks.
 
JLSE

JLSE

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Flaminpyro said:
They can also die from too many photons bouncing around inside of them it's an optical over load, I don't know the correct term so I'm sure someone will pop up and give us the right discription of what happens.
So yes they can die and not from heat or over current :whistle:
Click to expand...


This is the idea.. From my understanding it is the level of
optical flux within the cavity.

An easy way to see this in action is to point your laser into
a mirror... EDIT* don't do this... it will most likely toast it!

This type of feedback can be useful however when stabilizing the output
at currents just above threshold. I have read that the 445's can be
run in single mode with a stabilized output by creating a 'pseudo'
cavity with feedback from different lenses.. Will look for the link.

Doesnt matter how big the heatsink is, and unless an over current
blows the die leads like a fuse, it isnt the current that kills it.
 
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