445 nm window break...

[Hiemal]

Hey all, sad day for me. In the process of trying to modify the lazerer rifle I have, I somehow managed to break the window on the diode... I swore loudly and stood there for a good 3 minutes at my failure.

After calming down, I actually successfully removed the window, (without any decanning tools!) and the diode still lazes, without any power drop whatsoever. If anything, the output is actually even cleaner than before!

But, my main question is, how long do these diodes typically last with their windows broken? I've never really seen a definite answer.

 

[AnthoT]

I'd think it would be the same but they just would become that much more fragile. Now if you get dust in there you're laser will break. But if you make sure it stays clean and nothin gets in there it should be fine

-Anthony

 

[rocket689]

Make sure that you keep the collimating lens in the all of the time.
Dust and foreign contaminants can degrade the internals, but I always figure that the currents we drive them at will degrade them faster anyway. :beer:

 

[DTR]

Yep I will second that. I would never take the lens out again. But ultimately it will degrade quicker than if it stayed sealed due to interactions with Oxygen and dust particles in the air that it most likely has already been exposed to. Also there is a chance there are still small particles of glass in the housing that can cause you problems as well.:cryyy:

 

[Trevor]

InGaN diodes degrade with air - that's why we never see open-can blue or violet LD's.

InGaAs on the other hand do not degrade in the air - hence the open-can reds.

Trevor

 

[Hiemal]

Out of curiousity (I'm not questioning you guys' knowledge) but is there some website that shows that blues do indeed degrade in open air?

Also, what should I expect with the diode now? Should I sell it at a greatly reduced price? ($20?) Obviously, it still works so...

 

[Trevor]

We've had members here confirm that an InGaN diode died within three months of being decanned. I'll look for the threads when I get a chance.

Trevor

 

[Bluefan]

Jsut to make you feel better: today one of the technicians at the university here broke a photon counting photomultiplier tube. It was very difficult to insert into it's socket so it required some wiggling. The glass tube was fragile and a crack appeared while putting it into it's socket. Say goodbye to a few thousand euro PMT.

 

[Blord]

The university has enough money. We have to pay the laser stuff from our own pockets.

 

[Bluefan]

The university doesn't have enough money with all the budget cuts. It's not his personal stuff, that's true, but still it doesn't feel great to break a few thousand euro device.

But I blew/broke diodes myself too, nothing new.

 

[pullbangdead]

It's not going to hurt anything to be exposed to air, I promise. No significant effect from the lack of a can alone.

The only thing is that it's easier for a foreign object or contaminant to mess it up though.

 

[Hiemal]

Guys, I just want a definite answer.

Yes or no, should I get a new 445 nm?

 

[pullbangdead]

Guys, I just want a definite answer.

Yes or no, should I get a new 445 nm?

It still works, right? Use it til it dies, just like every other laser you own. There's no reason to treat it any differently, except being more careful to not get dirt in it.

 

[Trevor]

We've had several members report (I believe several times during the era of 8X BR and a couple times during the reign of 445nm) that after decanning an InGaN based laser diode, it slowly degraded over the next few months.

Would you say foreign objects would be to blame for that? At the time I read many posts - I thought including some from yourself - that stated exposure to air was to blame.

Is this not the case? If it is not, why do we see open-can reds but no open-can BR's?

Trevor

 

[pullbangdead]

We've had several members report (I believe several times during the era of 8X BR and a couple times during the reign of 445nm) that after decanning an InGaN based laser diode, it slowly degraded over the next few months.

Would you say foreign objects would be to blame for that? At the time I read many posts - I thought including some from yourself - that stated exposure to air was to blame.

Is this not the case? If it is not, why do we see open-can reds but no open-can BR's?

Trevor

Some people have said the facets will degrade with exposure to air. This is true for GaN facets...but these 445nm diodes have coated facets. The facet of the semiconductor itself is literally coated with glass, the semiconductor isn't exposed.

An uncoated facet will degrade, there is literature showing this. These lasers have coated facets. There's nothing to oxidize, because the facet is already coated with an oxide material.

Why closed cans? The better question is "why not?". These diodes are more expensive overall, so the percentage increase in cost to add a window is smaller than for a red diode. You also do need a can if the facets aren't coated. If you're a diode manufacturer and you need cans for some products anyway, and it adds very little additional cost per unit, it may well be cheaper to just put all the diodes in cans. And it's extra insurance.

Or maybe that's simply how the customer (Casio in this case) ordered them. Cooling fans, like in projectors, suck in a lot of dust. Dust can short out devices, so sealing the tiny wires in makes sense. Maybe the reds are simply designed in such a way that they're already sealed away from dust and the can is a larger marginal increase in cost (relative to the whole cost).

 

[Trevor]

Some people have said the facets will degrade with exposure to air. This is true for GaN facets...but these 445nm diodes have coated facets. The facet of the semiconductor itself is literally coated with glass, the semiconductor isn't exposed.

An uncoated facet will degrade, there is literature showing this. These lasers have coated facets. There's nothing to oxidize, because the facet is already coated with an oxide material.

Why closed cans? The better question is "why not?". These diodes are more expensive overall, so the percentage increase in cost to add a window is smaller than for a red diode. You also do need a can if the facets aren't coated. If you're a diode manufacturer and you need cans for some products anyway, and it adds very little additional cost per unit, it may well be cheaper to just put all the diodes in cans. And it's extra insurance.

Or maybe that's simply how the customer (Casio in this case) ordered them. Cooling fans, like in projectors, suck in a lot of dust. Dust can short out devices, so sealing the tiny wires in makes sense. Maybe the reds are simply designed in such a way that they're already sealed away from dust and the can is a larger marginal increase in cost (relative to the whole cost).

...useful information. Thanks! :beer:

Trevor