There's a kind of microscope which you can fit in eg the chuck of a pillar drill or mill, adjust the position of the workpiece so a scribed mark is central, then replace it with a drill bit - which seems to me to be the best way to do accurate drilling, though there are other methods, eg wigglers or lasers.
But what is the correct name for such a microscope? Anyone got one for sale?
Thanks,
-- Peter Fairbrother