WordNet records no synonym and no antonym for collimator. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a small telescope attached to a large telescope to use in setting the line of the larger one
optical device consisting of a tube containing a convex achromatic lens at one end and a slit at the other with the slit at the focus of the lens; light rays leave the slit as a parallel beam
Synonyms, antonyms and the broader and narrower relations for collimator come from Princeton University’s WordNet. Full sources and licences.