Have a look to this
white paper[
^] from a provider of camera devices and lenses: it will give you the criteria to set-up your system basing on the required image size and distance.
Have also a look at these
lenses[
^]: in the section
MACRO, there is the
MR8/O device, that is able to give you a frame of 0.8 by 0.6 mm when used with a 1/2" CCD. This means that you require a camera with a 1/2" CCD and a resolution at least of 800 by 600 pixels. Well, if you have a look at the camera devices in the same site, you can see that models with a 1/2" CCD have all a resolution of 1280 by 960 pixel. Then, theoretically, you could grab images with a resolution of
0.000625 mm per pixel which is better than what you asked for.