Diode glitch.

[Marco Polo]

A few years back - quite a few years now - I bought a host from Ehgemus and installed a 638nm Osram diode into it. This laser has seen it all - hard drops onto concrete and brick. Sub-freezing temperatures from being left in the car all night. Searing summer heat from being left in the car all day. All this while being fairly decently overdriven - it puts out a solid 190mW - and never an issue, until today.

The laser fell off my bed and hit something hard. I could tell from the sound of it. I picked it up and thought nothing of it, but when I aimed it at the wall the output was all wrong. I pulled the lens and the diode output was just nasty. Time to replace, I figured.

I've always been a firm believer in 'percussive maintenance' so I aimed the laser at the wall and gave it a few solid taps. And the damndest thing - on the third or fourth hit, the diode output went from basically jacked up to perfectly normal. The cleanest single-mode profile you could hope to expect. I put the lens back on it and dialed it in and not a further problem.

I'm going to guess that the diode is about to die and this is just a lucky repair by banging on it, but who knows. Anybody else experienced this? Hopefully I'm wrong and this diode has a few more years in it, but we shall see.

 

[Encap]

Sounds like an electrical contact/continuity of one sort or another problem caused by the drop and cured by some solid tapping--Solder joint, dirty Al threads --who knows.

Be glad it is working again. Clean the threads on the tailcap and battery tube. Have had a unit go dim and fixed by cleaning the threads for best possible electrical contact.

 

[CurtisOliver]

This came to mind.

It seems electrical like Encap has already mentioned. You just got lucky with your 'percussive' maintenance.

 

[BowtieGuy]

One thing that I've found (mostly with flashlights), is that if you have a multiple battery host, and drop it just right, you can damage the button (+) on the battery, and lose electrical contact.
It's probably a long shot, but it's something else to check out. Good luck with your 638nm, I hope you do get to see some more years out of it! :yh:

BTW, nice to see you posting again!

 

[deadshadow]

since you noted that output was wrong my guess is that something got in front of the diode's window and messed the output,while this would lead to a catastrophic failure of the diode if the diode was a high powered as the junk would fried and cracked the diode's window,in your case looks like after some taps the junk just got out of the window without burning due to you lower power laser.

 

[diachi]

Sounds like an electrical contact/continuity of one sort or another problem caused by the drop and cured by some solid tapping--Solder joint, dirty Al threads --who knows.

What? No it doesn't.

He dropped it and the shape/quality of the beam changed, how would a continuity problem cause that?

Clearly some junk somewhere in the optical path, either a broken diode window or some other FOD.

since you noted that output was wrong my guess is that something got in front of the diode's window and messed the output,while this would lead to a catastrophic failure of the diode if the diode was a high powered as the junk would fried and cracked the diode's window,in your case looks like after some taps the junk just got out of the window without burning due to you lower power laser.

^^This.

Also, if whatever caused this is still in there it's possible that the problem could resurface or the debris could cause damage to the diode.

 

[paul1598419]

I'd say you got very lucky to get it working properly again, but I would not chalk it up to a repair well done. This will likely resurface at some point and the diode will eventually need replacing. Like most electronic devices, lasers don't take sudden accelerating forces well.

 

[Encap]

What? No it doesn't.

He dropped it and the shape/quality of the beam changed, how would a continuity problem cause that?

Clearly some junk somewhere in the optical path, either a broken diode window or some other FOD.

^^This.

Also, if whatever caused this is still in there it's possible that the problem could resurface or the debris could cause damage to the diode.

Yes could be. All's well that ends well -- at least for the moment.

 

[hoo7h]

Marco I am actually really intersected in following up news about this diode lol. Keep us updated. Let's give it a name shall we ?