Definition of disc micrometer in English:

disc micrometer

(US disk micrometer)

noun

  • 1Astronomy
    A micrometer in which the image in a telescope or microscope is made to fall on a circular disc, placed at such a position as to match the image in diameter, the position and diameter of the disc then allowing the angular size of the image to be calculated; now rare and historical.

  • 2Engineering
    A micrometer in which the two jaws end in a circular disc to provide a larger grasping area.

Origin

Late 19th century; earliest use found in American Journal of Science.