Servo-Motor-Mirror-Processor
It may look medieval but it worked to process a 20 inch and a 16 inch mirror. Over 500,000 moves! OUCH LOL. I have the huge servo motor / driver, ball screws and ball spline still. Don't know what you think about doing that sort of thing but I guess its secondary. However I sense you have a very organized approach to a build. The guy who handled mech on this project was a hack(understatement!) A friend and I wrote the VB app to pump data into an LM628 chip that sent the signal to the servo amp.