Glass scales for UHU quadrature input?

[kwackers]

Hi, this is my first post so please be kind...

I've ordered the parts to make the UHU servo controllers and am considering how to fit them to a machine.

Since I was considering fitting the machine with glass scales anyway I was wondering if there was any problem using these to provide the quadrature inputs for the controllers.

Obvious benefit would be positional accuracy since the position would be correct regardless of leadscrew backlash, however since this very backlash would provide 'loose' coupling between the motor and the controller I'm wondering if there are likely to be any feedback issues with this.

In short has anyone done this? Is it likely to work for ballscrews but not for acme threads (due to the increased backlash)?

Any input gratefully received before I spend to much on the wrong things

Steve.