dhenry:
As mentioned, 0.01mm per integer from the ADC is adequate, but 0.1mm isn't.
I don't know what exactly you are trying to achieve but 0.1mm seems to be well below what a (untrained) human eye can detect.
Maybe you want to step back and see the minimum resolution / accuracy required and what that corresponds to a voltage signal for your adc and go from there.
I posted a little explanation of how the error can be magnified just now if you get a chance to read it but I'll do a little working backwards as you suggest too.
Thanks a lot.