I have a 2.3W laser on my cnc. I'm using the z axis to turn it on and off. Works great, I just need to turn down the power. It has a PWM/TTL. I don't want to bother trying to figure out how to hook up the PWM. So, could I stick a potentiometer in between the laser and the transformer? Or would that cause problems with other thing like the TTL?
Look up how to design a voltage divider circuit. Voltage in would be 5v and design it for about 1.5v out for starters. Then connect the out voltage to the PWM of the laser. Also connect the grounds. Put a pot in the circuit to alter voltage and power. Don't expect to engrave photos because you only have one power.