Any of various instruments for facilitating the visual comparison of two objects or images; especially one that projects shadows or transparencies of them on to a screen.
Origin
Early 20th century; earliest use found in Science.
Definition of optical comparator in US English:
optical comparator
noun
Any of various instruments for facilitating the visual comparison of two objects or images; especially one that projects shadows or transparencies of them on to a screen.
Origin
Early 20th century; earliest use found in Science.