Optical computer mice have a resolution of 12000DPI, giving a pulse each 2µm in theory. What it is like in practice shows my video:

More results of my test series are available on my project page:

http://homofaciens.de/technics-machines-cnc-v3-x_ge_navion.htm

Computer mice are Human Input Devices rather than linear sensors for CNCs. There is more Citizen Science to come during the build process of my "CNC for 194 countries"...