Mel asked:

>    I need your help in developing a new device -- a piezoelectric servo.
>Remember the crystal (or ceramic) phono cartridge, where, if something (like a
>phono record) wiggled the needle, you got a voltage on the output terminals?
>Shouldn't it also work backwards?  That is, if I put a voltage on the
>terminals, shouldn't it wiggle the needle?

(quite a bit skipped)

  Micro-positioners common in the optics/photonics field use
  just this mechanism to produce controlled movement of an optical
  element microinches at a time under digital control.

  Reg Neale