The units I used were based on very small stepper motors, operated as two phase induction motors. The mirror was very light and very small, attached to the centre of the motor shaft on a flat.

Position Feedback was used to stabilse everything, and that consisted of another mirror, a linear photodiode array and an IR LED

The electronics were suprisingly straight forward.One winding was driven pretty well continuosly, and the other modulated with the desired position signal.

90 deg bandwidth was around 4Khz.

I didn't design the galvo system.

Steve