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ArcticMyst Security by Avery

What is wrong with this laser?

Benm

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First find out what the actual problem is!

From the whole thread i can conclude that it draws about the amount of current that it should, yet ouputs very little, but some, light. This sounds like a broken (led'ed) diode to me.

This is NOT likely to be caused by a reverse battery: that would probably damage the driver, resulting in a different current draw than when produced. If not, it's not likely to damage the diode even if the full battery voltage was applied to it in reverse (laser diodes survive reverse biasing by a couple of volts, usually more than the datasheet specifies).

The question remains how it was led'ed in the first place: mechanical damage seems unlikely with proper packaging. The crystal facets on a laser diode are not that easy to mechanically break, and if it sustained a heavy shock in transit you'd expect other parts to be damaged or dislodged.

Sending it to a third party for analysis may be a good idea, but if it's just led'ed without any mechanical or electronic damage it would be impossible to determine the cause.
 





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Thanks for the input Benm! I'll try and send it to someone willing in the US
 
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Benm

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Another pair of eyes on it might help to find a cause - if there is any to be found.

In all honesty i must say there is a large chance of this remaining a mystery. If no mechanical damage or electrical damage or fault is found, determining what killed that laser diode is impossible. If anything is found that'd clear things up quite quickly.

Downside is that fluke failures like this just happen when you drive laser diodes pretty hard. I've had some diodes die on me for no reason at all - one day worked fine, next day led'ed with the same batteries, same ambient temperature and all.

These things can have a an avalanche effect. A small defect on the output facet occurs and starts absorbing light, stressing that facet very badly. Something like that can cause a complete failure in a split second. Something like that can be a manufacturing fault, but also simply a speck of dust landing on the laser diode.
 
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Ummm, not so. In the very beginning you were using words such as "scammed", "ripped off" and so on so yeah, you were pretty aggressive and then calmed down and edited the title and posts.
 
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Ummm, not so. In the very beginning you were using words such as "scammed", "ripped off" and so on so yeah, you were pretty aggressive and then calmed down and edited the title and posts.

Yup. But I guess he simply assumed nobody read the first draft.
 
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Ummm, not so. In the very beginning you were using words such as "scammed", "ripped off" and so on so yeah, you were pretty aggressive and then calmed down and edited the title and posts.

Only edited the very first post and title (and this post). Nothing else has been edited. I asked if it looked like I got scammed, I didn't accuse anyone. Simply asking isn't accusing. Ive apologized to gozert long ago.

Anywho, will be shipping to DTR tomorrow morning.
 
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id like to state that those diodes do not last very long at 650mA according to DTR. when asking him about building my laser, i asked him to set the current at 650mA he said "they dont seem to last nearly as long at 650mA as they do at 600mA , so i dont recommend it" (not exactly what he said, but its pretty damn close) so its very possible that the second you turned on the laser, that upsurge of power that occurs when turning on lasers happened to burn out the diode. it would be a one in a million kind of thing, but its very possible and something to consider. it also means neither of you are responsible for what happened, and i find that most likely.
 
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DTR Received the laser today. Waiting on his analysis and then I will contact Gozert from there :)

Hope all goes well
 

Benm

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@micheal: driving them that hard could be problematic indeed, especially when you do so right after taking them out of the mail in winter. Cold temperatures are usually a good thing, as they make laser diodes more efficient. This could be a problem when driving them far over spec as it increases the chances of catastrophic optical failure.

Microscopic inspection may clear this up: if its a cleanly damaged output facet on the diode optical overpower is likely to blame. If there is anything on the output facet (like a burnt on piece of dust) that would more likely to be the cause of the failure.

A spec of dust doesnt prove anything though: it could have been there before shipping, got caught during or after. With canned diodes dust damage often bakes onto the output window, but with canless diodes it'd deposit straight onto the die surface and cause damage there.
 
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@micheal: driving them that hard could be problematic indeed, especially when you do so right after taking them out of the mail in winter. Cold temperatures are usually a good thing, as they make laser diodes more efficient. This could be a problem when driving them far over spec as it increases the chances of catastrophic optical failure.

Microscopic inspection may clear this up: if its a cleanly damaged output facet on the diode optical overpower is likely to blame. If there is anything on the output facet (like a burnt on piece of dust) that would more likely to be the cause of the failure.

A spec of dust doesnt prove anything though: it could have been there before shipping, got caught during or after. With canned diodes dust damage often bakes onto the output window, but with canless diodes it'd deposit straight onto the die surface and cause damage there.

That's very interesting! Well, I hope to hear an update soon-ish
 
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Okay, DTR is reporting a bad diode. Have PMed Gozert to come to a fair conclusion for this
 

Benm

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Bad diode is no surprise, but what made it go bad? Probably just led'ed due to driving it very hard.

Luckily it's not an overly expensive diode, but i'd turn that driver down a notch before replacing it ;)
 

Gabe

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Bad diode is no surprise, but what made it go bad? Probably just led'ed due to driving it very hard.

Luckily it's not an overly expensive diode, but i'd turn that driver down a notch before replacing it ;)

Agreed :)
 
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Bad diode is no surprise, but what made it go bad? Probably just led'ed due to driving it very hard.

Luckily it's not an overly expensive diode, but i'd turn that driver down a notch before replacing it ;)


How does one go about doing this? Just my curiosity as DTR will be fixing it for me anyway.
 




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