there is DRO which are equipped with 5 micrometer glass encoder
those encoder are quadrature and most of them differential (a+a-b+b-)with index often
it will be very easy to amplify and recopy the signal
i have made a little prototype with a motor for raising up or down a thread mill equipped with an trapezoidale screw and an impressive gear box
i fixed it on a piece of wood with tape
i use a linear mylar encoder from a printer and i put the signal on my hp uhu working at 24V for this experience
guess that the rigidity of this was (censured)
i put my comparator
precision 1/20 of milimeters !!!
with the motor moving a pure mechanical nightmare !!!
there was some hunting on the begining but i manage to parameter uhu very well . this piece of .... was positioning very well.
So i believe that with a very good encoder it can be done.
i try to use a rotary encoder with poolie but vibrations make it very difficult
Is there any way to get more info on those glass scales?