Problem with DILAS laser

[Branson33]

Hey fellas (and possibly women?)
I got a DILAS single diode fiber coupled bar today, and something seems strange about it. I contacted DILAS asking for the datasheet but it’s an OEM Module I guess, but I found a datasheet for the same exact diode (I believe anyway) and it says they run at 1.9 volts and under and around 50 or so amps for a 30 watt diode which I have. But I plug it on up to the trusty old power supply, set the bolts to 1.9 just to be safe I always put it right on the given voltage and I set the amps to above threshold...but it doesn’t lase and is actually at constant voltage and not current...so I push it up to 2 volts and that raises the amperage a little bit but it’s still at constant voltage. So it seems it’s not dead but why is it forcing me to push it up to such a high voltage I’m scared I’m going to kill this expensive ass diode lol any help would be great. Should I continue to push the voltage up until it hits constant current?

 

[paul1598419]

If you have a CV/CC supply the diode will only pull the current it is set for at the Vf of the diode array which could be higher than the data sheet you have for it. It may not even be the right data sheet. I would allow the diode to run at whatever voltage it wants to as long as you keep the current below 10 amps. That 50 amp spec might not be right either. It should lase at a few amps if it is a good array.

 

[diachi]

If you have a CV/CC supply the diode will only pull the current it is set for at the Vf of the diode array which could be higher than the data sheet you have for it. It may not even be the right data sheet. I would allow the diode to run at whatever voltage it wants to as long as you keep the current below 10 amps. That 50 amp spec might not be right either. It should lase at a few amps if it is a good array.

50ish amps is correct for those 30W Dilas fibre coupled diodes, but you're right, it should start lasing way lower.

Of course, it'll be IR so keep that in mind OP. Won't be very visible, if at all.

 

[Branson33]

Alright will do guys, I don’t think it’s dead or else it would be a short, but I’ll let it go up to the voltage it needs to pull about 10 amps or so and tell you how it goes

 

[Branson33]

Alright well I got it to burn plastic with 3.3 volts 15 amps. So that’s pretty good haha. The side of the box has 43a on it, I’m wondering if that’s part of the serial number or if it’s the amps at max power. Kind of confusing to read when the whole dang label is in German. (Btw the diode is brand new came in sealed package with a glove and indium foil too)

 

[paul1598419]

You will need to get a terminator for the fiber output so you can add a lens to collimate the output. What do you have planned for this 974nm laser? I don't know that I would try to push this all the way to 50 amps, but it really depends on what you are going to do with it.

 

[Branson33]

Honestly I have a slight or severe obsession with laser especially the modules like this, so probably nothing to important, maybe try to micro machine some things

 

[WizardG]

Happy to hear you got some coherent light outta the thing. My first thought when I read the OP was that the OEM module might have been constructed with the polarity reversed from the usual setup. Which would have been a real downer as you turned up the voltage!

 

[Benm]

How are you measuring the voltage though? Are you just using 2 wires from the power supply, or a 4 wire solution so the power supply can actually see what's being delivered to the load?

The current indication on the power supply would be accurate regardless, but the voltage not so much if using 2 wires: you have things like wire resistance and contact losses to account for. With things like 12V/1A that's rarely a big problem, but at such low voltages and such high currents it can become really problematic.

If you're pushing something as hard as 50 amps don't be surprise by voltage drop in leads and connections, and if you cannot do 4 wire connections, rely on current limiting on the supply, and perhaps put a multimeter directly across the diode terminals to measure the voltage there. That may be a lot lower that what your power supply is indicating!