Help with A-Type M140 Laser diode

[Pinto]

I have this laser here but I'm having a lot of problems with it.
(1 8W 445nm A Type M140 Blue Laser Diode in Copper Module w Leads | eBay)

I'm trying to supply it with a computer PSU but it has a very high resistance
measurement when measuring with a DMM, around 14k ohms. That doesn't
seem right at all. is it blown? (measured across the +/- terminals of the
laser)

I've been driving it with a LM317 Current limiter which by itself seems to
function properly from the measurements I've gotten. However when I
connect the diode to it, the current immediately drops very low, from 1.14
Amps to .005 Amps.

If someone could let me know what I'm doing or give me the bad news I'd
really appreciate it.

If it matter's, it's also in a large heat sink.
it lights up but VERY faintly, when it does at all.

Also as an aside, when it's on, there is a blue halo around the center laser
point. is this normal or is there something wrong with my setup?

thank you very much.

 

[Pi R Squared]

A computer PSU? What voltage is going to the LM317?

Alan

 

[WizardG]

Schematic of your regulator circuit please. And if it's the typical LM317 current regulation circuit check the voltage across the set resistor with the circuit under load. I recommend using a test load rather than risking your diode on a potentially flaky driver.

 

[Pinto]

A computer PSU? What voltage is going to the LM317?

Alan

~5V output

 

[WizardG]

5 volts isn't enough. ~4.5V across the laser diode + ~2V loss in the regulator means you won't see any significant light output until you have at least.....about 2 more volts.

 

[Pinto]

I'll try that when I have a chance. I switched to a different PSU this morning with the exact same setup and now the diode is not nearly as bright as it was when first testing. Even when switching back to the original. I can't even see it when my goggles are on at this point.

I'm hoping I didn't accidentally kill it at some point?

 

[Sta]

I'll try that when I have a chance. I switched to a different PSU this morning with the exact same setup and now the diode is not nearly as bright as it was when first testing. Even when switching back to the original. I can't even see it when my goggles are on at this point.

I'm hoping I didn't accidentally kill it at some point?

Is the output still coherent?
If so, you probably haven't killed it.

 

[Pinto]

I'm sorry I'm new here, and to all this. Can you define coherent.

 

[Sta]

I'm sorry I'm new here, and to all this. Can you define coherent.

Is it all one color, and can you focus it into a thin beam with a lens?

 

[Pinto]

Yes I believe so. I'm sure it will be helpful if I update my post with pictures. I'll do so as soon as I get home later today.

Thank you very much for the help so far.

 

[Sta]

Yes I believe so. I'm sure it will be helpful if I update my post with pictures. I'll do so as soon as I get home later today.

Thank you very much for the help so far.

Okay that's good.
When it's defocused, are you seeing lines of darkness through the output?