Category theorists seem to enjoy coming up with confusing nomenclature.
compared to CS nomenclature which is all crystal clear
Correct. The term "optics" is used by analogy; functional optics let us "zoom in" on parts of a data structure, and "zoom out to" a data structure surrounding a value.
The name lens came from the property of their letting you "focus" onto parts of a larger data structure. The prism nomenclature is more tenuous - prisms evoke the imagery of a beam of light splitting into its constituent parts, and with a prism you can see a particular facet of the whole (sum types).
This has to do with category theory and programming notions of optics and lenses.