19" 2CH laser diode driver

I just want to show the project I'm currently working on, a dual channel laser diode driver in a black 1U 19" case. I can put out 2A per channel, adjustable with a ten turn pot. The panel meters aren't hooked up yet, but they should be 2A full scale. The second pot is for the analog modulation, the modulation currect is adjustable. This way you can drive the laser with 0 to 5 V from just at the threshold to the max. I added a key switch just for the fun of it. I've used the driver frequently, it's very good regulated and filtered.

I plan to redo the circuit, I made an error in the design. In the next design I'm going to include a better stability, photodiode feedback, maybe a TEC driver, a standard D-SUB 9 output, and different protections like an interlock connection and overvoltage protection.
This last one is important, I already blew a (cheap) diode by a bad connection. If you disconnect a laser diode but not turn of the current, the driver rapidly increases the voltage. If you then make contact again, this higher voltage will damage the diode. So, a short break in the connection can kill your diode, but not if the driver shuts down if the voltage starts rising too hard, which I'll be implementing.

My next project will be a 25A laser diode bar driver. I'm curious, would anyone be interested in a 0-2A driver with these options and safety features? If I have some spare time, I can make some custom drivers.

Those Rack Mount cases are sleek... :gj:

As to the 2A driver interest...
What would the price be... and what circuit (voltage or current) and
type of regulator are you using..

Jerry

I'd be interested in a 25A driver if the price is right.

lasersbee said:

Those Rack Mount cases are sleek... :gj:

As to the 2A driver interest...
What would the price be... and what circuit (voltage or current) and
type of regulator are you using..

Jerry

Click to expand...

The rackmount cases are a bit expensive, the whole hardware costs for this version are around 75 euro, about $110 I think. But the panel meters I now use for other stuff are better but won't fit in this case, and I'm not that happy with the case. A single channel driver can be made at about half the hardware costs if not in this case, maybe that would be interesting.

I haven't made a 25A driver yet, but it would be more difficult because thermal issues start to play more. But I haven't got much time, if anyone wants a driver, I would make them one by one, so I may just as well make them custom, if anyone needs or doesn't need specific features. But first, I need time to build my improved design, to see if it really works that good.

Edit: To answer your question: I use a constant current driver. The circuit senses the current and controls it with a feedback loop. I use a slower and thus well filtered system to set the current and a fast circuit for modulation.