Getting my hands on some 40W DPSS laser pumps for use in a DIY laser cutter machine. There are some power supplies out there, but they're "from china" and I'd firstly like it to last more than a day, and secondly to be able to accurately control the power output.

For those who don't know what a Diode based laser is (as opposed to a gas chamber one) - these units only require between 0.2V and 2.0V but light power output is adjusted purely by current - for a 40W laser, current can be around 45A @ 1.8V (nominal); basically they're just super powered LEDs.

The lasers are PWM friendly, so adjusting output to 1.8V (rated voltage) and building a basic SMPS without the smoothing capacitors may be a viable option.

The main question is the transformer for the job... Unlikely I'll find a 600VA+ model with a 5v 1A (current feedback) and 1.8V secondary so I'll likely have to either get one custom made (expensive?) - or find an alternate method (Like bringing down a 5V model to 1.8V).

Anyway - please comment, ideas are the game and thankyou in advance.

[EDIT]

I'd very much like to be able to control the power output via a PIC, as well as accurately measure the current via the same module - from the PIC to display I can do, my main concern is the mechanism for controlling current via the PIC (PWM driven FETs?).

 

Rather than staring from scratch. High current 5V supplies are common. Both linear and switching. 50A <$50

A voltage hack should be pretty simple. 5V to 3V out.
If you can hack one for constant current it would be a good start.
A constant current bench supply might be another option. I haven't found one under $500 though.

Does it have to be efficient? Adding a constant current linear regulator to a low cost 5V/50A supply and dumping 30 watts is an option.

 

True - Larger ATX power supplies have dedicated ~500W 12V rails for SLI and CrossFire (Multi-GPU scaling).

Also, found this gem: http://cds.linear.com/docs/en/demo-board-schematic/311asch.pdf
(12V to 1.1 - 1.8V 60A DC-DC PSU)

May be on to something here.