I'd like to see what your Stocker Yale actuator looks like. I found one of their linear actuators on line but not much else.
We just used thin aluminum strips cut from a soda cans with General Scanning servos for image blanking or beam flags. I posted photos of this on PLF somewhere. On the old school tech methods I found the edge shape or thickness didn't make much difference as long it was flat black. .o62 aluminum sheet stock worked great. Neither of these methods caused beam flares as they went from open to close.