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Strike 3, demo laser display keeps failing .pix.

Down with Umbrella

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Hey folks,
I could really use some advice. I'll try to keep this short.
A few months ago a friend whom is also an engineer employed by a major company in the Illinois had been given a project to build for a museum. The objective was to demonstrated the properties of a coherent beam inside an acrylic medium. One fiber was flexible, another cylindrical, and the last square.
The challenge 8 hour run time.
Easy enough right?? Well my friend had many things on her plate asked me for advice because, well, I <3 lasers:whistle: and she, despite being very smart, really didn't have a background in photonics.
Things to consider:
A)I don't actually work for her employer so I could only advise.
B)I wasn't privy to the details on the project.
C) I'm not there to build it, test it, measure it etc myself.

The failure.
Strike 1
Because budget restrictions were tight I recommended three LOW power modules from DTR with his aluminum mounted hs. Considering safety I advised using <50mW (RGB)options with a laser stop. This all burned up within a few hours. (Larger hs, fins & active cooling should have been used here)

Strike 2
Drastically lower power eBay 5mW modules with equal heat dissipation. These failed too and barely visible.

Strike 3. Time to spend some more money:
I recommend 3 AixiZ lab lasers with adjustable pots. Looking at just the photo Aixis had provided I had her dial down the laser until it was at the minimum threshold to be visible in the acrylic. AixiZ accidentally sent a 200+mW laser and some poor sap burnt his hand. They were swapped out and they like the rest despite fan cooled modules died after only a few days.

It's very difficult for me because I'm not physically there to see what's actually going on:undecided:

Ideally the driver could be pulsed with a 555 timer or TTL to reduce on time, or spend $$$$ on an official LAB laser.. not sure. Any other ideas? Laser pointers are my cup of tea. Not museum display grade operations.
 

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Cyparagon

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She keeps killing lasers, and you want us to tell you why, when you have no access to the device? Well, Aixiz makes decent stuff, so it either has to be overvoltage (of the driver), overcurrent (of the laser diode), or overtemp (of either).

Reflections back into the diode are a small possibility which could be fixed by pointing the module into the fiber at a (visibly negligible) offset.
 

Down with Umbrella

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She keeps killing lasers, and you want us to tell you why, when you have no access to the device? Well, Aixiz makes decent stuff, so it either has to be overvoltage (of the driver), overcurrent (of the laser diode), or overtemp (of either).

Reflections back into the diode are a small possibility which could be fixed by pointing the module into the fiber at a (visibly negligible) offset.
I know, I'm that noob being like FIX itttt. But I can't diagnose the problem either from a few photos. Nonetheless I'd like to be able to offer a solution.
Let me ask the question differently: other than CNI or another high end Lab laser supplier can anyone suggest a company that sells quality modules that are designed to run at this duty cycle?
Too bad They couldnt use a few HeNes:/

(Re reflections, a small offset could be made. )
 
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paul1598419

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You can find lasers on eBay that have a fiber optical cable couple on the output, which would negate the reflection problem. There are lab lasers as well that have fairly long duty cycles. Some are fairly cheap too. Under $100.00 each. This is where I would research an answer to this problem. You should be able to find some in the primary colors that should work for this situation.
 
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Cyparagon

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...can anyone suggest a company that sells quality modules...
So she can kill those, too? I'm already reasonably sure the implementation is to blame, not the lasers. Given the history here, throwing more money at it probably won't help.
 

Down with Umbrella

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So she can kill those, too? I'm already reasonably sure the implementation is to blame, not the lasers. Given the history here, throwing more money at it probably won't help.
Let me work it from that angle and report back. Thanks for the responses.

Paul, I'm looking at those right now, thanks for the link.
 

lasersbee

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A laser that is not overdriven from it's actual
specs and is power... again... as to it's specs
will have a much greater lifespan than 8 hours.

If the specs of the Laser being used are respected...
it follows that the problem is elsewhere.

Jerry
 

Down with Umbrella

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I double checked with her today.
-Proper voltage to the lab driver: 12VDC ✅
-the modules were all offset so the beam would appear to bounce off the sides of the tube. ✅

The museum said they worked fine for a few days then dimmed, then death. We may never know.

I agree laserBee we're not talking overdriving them for crazy power. I'm have tempted to order the same lab laser from AixiZ and do a multi day test.
 
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paul1598419

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I wonder if the problem could be related to very long duty cycles. Might work better if the drivers were turned down or the output was PWM to effectively do the same thing. It's near impossible to troubleshoot this problem second hand.
 

WizardG

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"-Proper voltage to the lab driver: 12VDC "

Is it just me or does this sound a bit odd? If the drivers were, in fact, intended to run from 12 volts I suspect those drivers may need additional heat sinking.
 

lasersbee

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I'm sure the drivers would be output adjustable.
Are they set correctly and not over driving the
LD's ???
Don't trust the seller to have set the current to
a safe long life Spec sheet current.

Jerry
 

paul1598419

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I've got several lab lasers that run on +12 VDC. That doesn't sound unusual to me at all. The drivers being set too high is definitely possible depending on where they came from and what output power they claimed to be.
 




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