First 520nm Consumer Kill?

[Wolfman29]

I guess it can happen to vets like me too!

I had finally got my 520nm laser built using the new diodes, and it worked perfectly. The window was a bit dirty, which was confusing (not sure how it got dirty - I kept it in the package until I was ready to install it into the laser). After I finished the build, I figured I would clean the window. I figured it was safe to run for a few seconds here and there to make sure it works, but you always clean the window of a high-powered laser so nothing bakes on! Anyway, it worked fine on some test runs. After some frustrating cleaning, the diode started having a weird output. See below:

I've never seen a zombification like this in a single-mode diode. It almost looks like the edges of the beam profile were chopped off like when one of the modes dies in a multimode diode... but these are single mode.

Anyway, this happened while cleaning. It was powered on occasionally, but not for too long to have too much internal reflection, I wouldn't think.

Anyway, can anyone diagnose this? I realize I will have to order another EXPENSIVE diode to replace that one (and I will have to bust this one one of the REALLY expensive silver host that it's in), but I am curious as to how this one died....

EDIT: Alright, well I knocked it out, so it's dead permanently. I guess I'll replace it! I tested it on my meter before I killed it and it was doing a measly 30mW at 275mA, so it definitely zombied. I think it was rapidly degrading, too. Not sure what was up.

 

[RA_pierce]

The output looks reeeally dirty.
How are you "cleaning" it?

It is still producing some output and could make a decent low power pointer once you clean all that sh*t off the window. So don't throw it away just yet!

Perhaps some other info might be useful for understanding what went wrong... and what to avoid...
Current input?
Power output before and after zombification?
What is the diode installed in?

Edit: You added additional info.

 

[ARG]

Wow, your camera makes it appear very cyan!

 

[Wolfman29]

It does make it appear cyan!

I already threw it away, so no use there.

So information, though: I was cleaning it using rubbing alcohol and Q-tips. I make a swirly motion while pulling away from the diode can, as I learned from Dave. It usually works just fine, but it was a lot harder with a smaller diode window.

The current input was 275mA. I actually didn't measure power before zombification, but I did notice a significant decrease in power loss after the event: prior to this, I could see the beam in my lit-home. Afterwards, I could hardly see it pointing it into the night sky. The diode was installed in a solid copper module which was then thermally glued into a solid silver host. There was no issue with heatsinking, I can assure you that much. My guess is that some of the rubbing alcohol may have managed to sneak its way past the window and shorted a lead wire before soon after evaporating, causing the diode to not be able to handle as much current and then degrading. Either that or it got on the diode face itself, but I doubt that.

 

[styropyro]

If this ever happened again I'd suggest to de-can the diode before powering it on like that. My guess is that it did die from internal reflection, but I am no expert on these things so hopefully someone more educated on the matter can chime in.

 

[Wolfman29]

Unfortunately, I would have had no way to remove the diode from the host without destroying the diode.

 

[Sigurthr]

Yep, the C.O.D. (cause of death) looks like C.O.D. (catastrophic optical damage). What a shame! Do you have a decanner? Next time just decan a dirty diode. I've never had much success in cleaning diode windows... lenses sure, but not windows.

 

[Wolfman29]

I do not have a decanner, unfortunately. And no means to do so, either.

 

[styropyro]

Dealing with those tiny 3.8mm laser diodes is probably pretty difficult so I'm sure they are a PITA to de-can.

Oh BTW, you were not the first to kill one of these at the hobby level: http://laserpointerforums.com/f55/gb-pl520-murder-fund-81496-11.html

Horrible news... My drivers got delayed from unforeseen circumstances and I got bored and decided to do some more testing on my diode. I had the whole rig set up and turned it up to 350mA and turned around to grab a clamp to hold it in place and at that instant my cat jumped up on my desk and knocked the whole thing over... my diode got a nice spike and poof.

 

[Wolfman29]

But those were intended to be killed, no?

 

[styropyro]

Yeah they intentionally killed two in that thread but that post is from a separate user that accidentally killed his own 520nm laser.

 

[scumbagatheist]

Guys, can I give my two cents on this?

First, which lens were you using?

Secondly, I used to use alcohol until I saw the residue left behind. I've switched to pure acetone, and it makes a tremendous difference. I'd also like to suggest in the very small LensPen. I have the 3 pack, and they really are a must have in our hobby.

One last thing; Let me reccomend using ONLY CO2 as far as compressed gas cleaning. The lens pen is perfect for the coating, but unless you bag that sucker, you can get dust on the brush. Even 91% Isopropyl is still 9% water, and will leave a film...not so with pure acetone. Also, microfiber anything is your friend.

Thanks

 

[Wolfman29]

Hmm. Good to know to use acetone. Also, can you link me to a good lens pen?

 

[scumbagatheist]

lenspen.com

 

[Wolfman29]

Well then. Can you recommend a product? XD

 

[scumbagatheist]

Oh, hell...Ok. Lemme look...