The slotted screws make me think it may have a bit of age to it, and that cross hatching is evoking a memory of a finish technique that I can't quite remember. As to an inspection stage, that is a good possibility. Scopes of various sorts as opposed to traditional microscopes. One would have to get a better idea of the lead screw threading in order to better determine as this would require tens of thousands adjustments at a minumum.