Blink Comparator

blink comparator [′bliŋk kəm′par·əd·ər]

(optics)

An optical instrument used to alternately view two pictures in the same visual field in rapid succession, to detect small differences in similar images.

---

Blink Comparator 

an astronomical instrument for finding variable stars, minor planets, and stars with large proper motions on photographic plates of the starry sky. The blink comparator is utilized in comparing two photographic plates of the same portion of the sky taken on the same instrument at different times. Both of the photographic plates are viewed through one eyepiece, and by flipping a special flap slide—that is, “blinking”—either one can be seen alternately. The platform on which the photographic plates are mounted is adjustable, which makes it possible to orient the plates with respect to each other in such a way that stars whose mutual position has not changed appear fixed upon rapid blinking. At the same time, objects that have shifted in the time interval between two exposures appear to jump. The images of variable stars have different diameters on the photographic plates, and a flickering or pulsating effect appears upon blinking.

V. V. PODOBED