Hello eltonjohn,
Using a PID algorithm for controlling a galvanometer in a digital design (DSP/FPGA) is a little bit overstated. A PID can be easier implemented in analogue. For example the control algorithm of the digital scanner amp from Cambridge Technology does not use PID. There are some other algorithms which will take advantage of a digital design like a dead-beat controller or a state controller.
Some months ago I planed to start a project for developing such a controller but the amount was too big for a small project. It’s a very interesting matter and I hope you will get some good results.
Bye,
cube007