It's a good stab, but the rotary stages in the picture don't seem to be for EO, since almost all EO rotary stages are driven by linear micrometers with worm gears. These look to be controlled by the hand knobs, which means they barely have about 0.5 degrees of resolution/accuracy/repeatability, whereas EO stages might have arcmin or double-digit arcsecond resolution, which is where the micrometers come in.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
I've tried googling different likely terms with no success. All the optical-stuff seems to be set up for use on a rail, not just on a table-top. Perhaps the same usage here, but on a bigger scale?
This looks factory-made to me, but a lot of old factory-made stuff like this will have some sort of little nameplate, and I'm assuming there's not one, or it would have been mentioned.
Aluminum tube frames - perhaps 1 x 1 hollow. Velcro attachment method. So, a lightweight item is being positioned.
Probably not a welding jig or fixture, but a #D adjustable "assembly jig" nonetheless for a 18 inch x 18 inch x 18 inch assembly that needs to be re-positioned regularly WITHGOUT it hitting or being flipped on a workbench - So it is lightweight but fragile.
Like a satellite or radio or radar or breadboard or controller or prototype assembly. The assembly is by people. They don't need precision locations unlike robots. But do need manipulation.
No burn marks or steel assembled pieces, so probably not for welding or brazing. No paint - not for painting or varnish applications.