Plane micrometer

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Parallel displacement of the beam path on an optical plane plate

The plane-plate micrometer is an optical precision mechanical component of theodolites and other optical measuring instruments. It enables the precise reading of pitch circles and scales by turning a precisely ground flat plate made of glass.

The parallel shift of the beam path is generated with the help of a micrometer screw , which is subdivided accordingly. B. to 0.01 mm or finer, for angle measurement to 1..10 ".

The micrometer found its way into the second theodolite around 1930 (see Wild T2 ), in which the fine reading of the horizontal and vertical circle was made by the coincidence of opposing partial circle locations.

See also: recording micrometer , stereo comparator .