optical stages and alignment, sending beams of light to specific locations.

https://en.wikipedia.org/wiki/Optical_table

Optical suppliers are

https://www.edmundoptics.com/ (highly recommend ordering their catalog)

https://www.newport.com/g/optical-tables

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=70...

Youtube channels on optics

https://www.huygensoptics.com/

https://www.youtube.com/@BreakingTaps

Remember, constructive and destructive superposition of waves?

Setting up a tabletop optics experiments is mostly optimizing alignment between different components (lasers, lenses and optical detectors etc), so you get the maximum power or the right kind of superposition. Alignment is linear (get the right distance between two components) or rotational (right angle). So you can build these linear/rotational mounts that will move/rotate your components precisely based on computer commands.

You can probably buy off the shelf robotics components off Alibaba that are better and cheaper at the same time. But I think distributed manufacturing is way cooler.

I believe these are used for laser and light experiments on an optical bench - a heavy desk with a pegboard-like top surface that holds lolipop-like lenses on sticks. Thorlabs is the Sigma-Aldrich or McMaster-Carr, or, Adobe, of the field.