im as new as they come in a world of arduino and the c programming ,
but have experience in Electrical and PLC automation, when the problem you mentioned arises it could be fixed with a couple of following remedies
1 Invert your outputs anywhere along your program so the laser fires on logic 0 or low. alot of the safety oriented programs do that.
2 You can create a debounce timer of some kind to ignore that sudden "blink" in the beginning of a boot process, or even insert a hardware "on delay" timer with say 1000 milliseconds, to let the Arduino stabilize and place it in series with laser ( solenoid or transistor or relay actuator of some kind)
3 I wonder if its possible to have the laser fire only if it sees a sequence of PWM signals which in turn again will ignore any bounce as well, you could probably do that part in software , its just my 5 cents.
and off i go to learn and become smart! have a great day