Thank you, jremington.
Thank you, MarkT.
Is constant current driver like this?
So I should use a DAC, not a digital pot?
Sorry that I didn't mention the use of the pigtailed laser diode.
The laser diodes are the light source, then I will take some pictures.
The shutter time is 250us, and I'm afraid that using PWM(or change the frequency of Arduino pins) will let me have a black picture.
So I need an real analog current, not a digital current.
I'm new to Arduino and electrics.
Thanks for helping me.