PWM control with a DDL circuit?

Hello,
i am new in the Laser section and an electrical noob (i am more a mechanical engineer)^^
I build myself one of the "DVD Laser engraver" with Easydrivers, Arduino Nano and a 1W 445nm Laserdiode.

As driver i used something like this:

Just that i add an Transistor E3055 at the GND to turn the Laser on and off.

Thats works fine but now i need an update. I will control the brightness of the Laser to engrave B&W pictures.

Is there a way to do it with that driver by adding a MOSFET instat of the Transistor or did i have to build a new driver (or buy one of the china ttl driver for 8$)?

I hope u can help me.

Thanks

(sorry for my english)

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