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Instrument for comparing something with a similar thing or with a standard measure, in particular to measure small displacements in mechanical devices. In astronomy, the blink comparator is used to examine photographic plates for signs of moving bodies. Machinists use comparators or visual gauges to centre or align work in machine tools.
This entry comes from Encyclopædia Britannica Concise. For the full entry on comparator, visit Britannica.com.