blink comparator

American  

noun

1. an optical instrument used to detect small differences in two photographs of the same field or object by viewing them alternately, switching rapidly from one to the other.

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Etymology

Origin of blink comparator

First recorded in 1925–30

Example Sentences

He used a device called a blink comparator, which compared two photographs of the sky taken at different times, so that a moving target, such as a planet, could be seen flitting back and forth against a background of fixed stars.

From Time

He examined scores of telescopic photographs, each showing tens of thousands of star images, in pairs under the blink comparator, or dual microscope.

From Time Magazine Archive