In search for DIY driver with modulation

[toxuin]

Hello, folks!

I am making a project where I need to solidify resin polymer with laser beam. I am also writing the firmware for it basically from scratch and would like to use a safe visible laser first in order to debug software and calibrate the timings and whatnot, but at some point it would be replaced with a more powerful near-UV laser.

I intend to use two diodes: one is 635nm 5mW (DL-3148-034) aka "visible one" and some undecided model ~100-200mW 407nm as "invisible one". (I know it will be somewhat visible though).

I need a driver solution for this setup. Ideally, it would be same driver for both diodes (except for the pinout), but if that's not possible I could build two drivers I guess.

So, after quite some googling and searching on this forum I just got more confused on particular driver design I should use. Could you advise me something that would fit my application?

- I do not care much about compactness and energy efficiency as I am not going to power it with batteries.
- However, I do care about it being DIYable because I want to understand how it works. Buying off the shelf device wouldn't get me peace, if you know what I mean.
- Obviously enough, such driver should allow signal modulation.

I am willing to learn and hear your wisdom on this topic. My background is programming and I am relatively new to circuit design. However, SMD soldering have never been a problem to me.

Oh, an I have a LM358 lying around if that'd do any good.

 

[diachi]

There's a 1MHz analogue driver based on the LM317 - uses some op amps, an LM317 and some other common components.

Schematic:

Instructions/details/PCB Layout etc:

Sam's Laser FAQ - Diode Laser Power Supplies

 

[Benm]

I've designed a circuit that would probably fit the bill:
Merghart.com - TTL/Analog controlled opamp based current source

I'm not sure how fast you need the modulation to be and have not tested the limits of that, but it works fine with signals as fast as 50 kHz or so for projectors.

The LM358 might not work in this application since it's common mode rejection range doesn't extend all the way to zero. It might work, especially when using PWM and not linear dimming right down to gournd, but that's something you should test.