Macrometer vs. Micrometer

An instrument for determining the size or distance of inaccessible objects by means of two reflectors on a common sextant

A device for measuring very small distances, objects, or angles, especially one based on the rotation of a finely threaded screw.

An instrument for determining the size or distance of inaccessible objects by means of two reflectors on a common sextant.

See micron.

A device used to measure distance very precisely but within a limited range, especially depth, thickness, and diameter.

Alternative spelling of micrometre

An instrument, used with a telescope or microscope, for measuring minute distances, or the apparent diameters of objects which subtend minute angles. The measurement given directly is that of the image of the object formed at the focus of the object glass.

Caliper for measuring small distances

A metric unit of length equal to one millionth of a meter