Can J tech photonics driver drive this diode?

[Asking for a friend]

Hello team,

I bought a jtech photonics laser drivers a while back and I must say it was the most well-made laser driver I have ever had.

I am using it to drive a Chinese "2.5W" 450nm diode with no huge issue. I was wondering if the driver can drive this diode here:
https://www.ebay.com/itm/7W-NUBM44-...770497?hash=item2802915401:g:6IkAAOSwcwhVQRfE

It is a 7W NUBM44-V2 450nm Laser Diode from "dtr laser shop" on ebay, a more reputable seller.

Looking at the pictures, when driven with 4.5A of current at 4.7V (21.15W of input power), the laser diode has an optical output power of 6.8W. When driven with 2.5A at 4.2V, the laser diode has an optical output power of just below 4.1W.

The laser driver I got from Jtech photonics has a "compliance voltage" of 8v when used with a 12v power supply, and can provide a maximum of 2.5A----I assume this means 20W of total power.

I am not an electronics expert and I am uncertain if the driver from Jtech can drive this diode properly----it can almost match the total
power input required by this diode (I can accept the minor deficit) but at different current and different voltages.

My question is:
Since the driver can only provide up to 2.5A max, does it mean it can only drive the diode to output about 4.1W of optical power? Or can
it drive the said diode closer to the 6.8W optical output since it can almost match the total power input of 21.15W?

Any guidance/comment/recommendation is wholeheartedly appreciated. Keep up the good work guys.


Thanks for your time and help in advance.


Kind regards,


Gordon

 

[kecked]

Diodes need a certain voltage called Vf the forward voltage. After that is meet it doesn’t matter the supply voltage as the driver deals with it. The diode optical power once Vf is established is governed by the current into the diode. So whatever the diode outputs at 2.5a opticcally is what you will get. This is why we use constant current drivers.. If we just control the voltage, the current demand would run away and burn up the diode. By controlling current, the voltage is self limiting.

So Input power doesn’t tell you what you want to know. You will see 4w and a very long life out of that diode when driven at 2.5a. In fact the higher current you run at the shorter the life of the diode. That’s a whole another story ...

 

[Asking for a friend]

Hello Kecked,

Thanks for your reply. That answers it. I do have additional questions tho (to help me understand this):

When I was driving the Chinese diode, I set the current to 1.5amp max. The diode only visibility emit light at about 30% pwm. Is this because there is a "minimum current" required by the diode? I assume in this case is 30% of 1.5amp?

I was trying to do 8 bit photo engraving on wood, and this means that I am loosing 30% of my color depth range which isn't ideal.

Looking ahead, if I get this diode, can I assume that it will have a higher "minimum current" and I will loose even more "color depth" range? What would you recommend as a minimum optical power requirement for wood photo engraving?

Also, since the driver can only provide up to 2.5amp, to get as much optical power output as possible, would I choose a diode with the highest Vf? I assume optical output power = Vf * current?

Can you recommend a place where I can get such diodes?



Thanks for your time.

Kind regards,


Gordon

 

[kecked]

Yes I forgot. There is a threshold current you need to set that so the diode is ready to conduct called the bias current on your driver. Set it so the diode just comes on then back it off till it comes back then advance slowly to point where it is still off but as far up as you can without lasing

 

[Asking for a friend]

Good afternoon Kecked.

Thanks for your reply again.

I looked long and hard at the driver manual and I can't find anything with regards to what you suggested, so I sent their customer service team an email for some advice on that.

And yes they also confirmed what you said in your first post about the 2.5amp and diode outputting about 4W.

May I ask for recommendation on places you can get quality diodes at reasonable places? I am sick of the Chinese cheap and cheerful diodes and their false claims....

Thanks for your time.


Kind regards,


Gordon

 

[deadshadow]

just to make it clearer you only have to care about current when driving a diode and only check the voltage needs to get the correct driver(boost or buck-linear),in your case if the driver says 2.5A max then you can't run your diode any higher than that no matter the total watts you were measuring.

 

[Asking for a friend]

Hi deadshadow,

Thanks, 100% clear now.

With 2.5A max I think I can get about max 4W of optical output power with a 445nm laser diode.

Kind regards

 

[deadshadow]

I'm glad I helped you to figure it out,if you are planning to get the nubm44 diode pair it with a stronger driver or else get a lower power diode like the ndb7875 to run it with this driver,it will be a shame to have 4w of underpowered diode with this terrible divergence.

 

[paul1598419]

Once you learn the part numbers of the popular diodes we use, you won't have as much trouble trying to get the right diode for your needs. I suggest you look at DTR's website as he offers many popular diodes at reasonable prices. He will also pair it with a driver for you and put it altogether in a module with the lens of your choice.

See: https://sites.google.com/site/dtrlpf/home.

Edit: Just in case you are unaware, the NUBM44 is one of the most powerful diodes we have, but its diverges so badly that it makes a line instead of a dot which can only be tamed with more exotic optics which will cause losses in power. Just because a laser diode can output more power it doesn't mean you will like the end result. So, you need to learn how much each diode diverges and what optics to use to make it more manageable.