Contact displacement meter

A contact displacement meter comprising:

• a casing;
• a contact supported by the casing movably in one direction;
• a scale which has a plurality of light transmitting slits arrayed in the one direction and is configured movably in the one direction along with the contact;
• a light-projecting unit which irradiates the scale with non-parallel light;
• a light-receiving unit which receives the non-parallel light having passed through the plurality of light transmitting slits on the scale, and outputs a light reception signal indicating a light-receiving amount distribution;
• a detecting unit which detects, as a plurality of peak positions, a plurality of positions where a light-receiving amount is at maximum or minimum in the light-receiving amount distribution on the light-receiving unit;
• and
• a calculating unit which calculates a distance between a reference position and a position of at least one light transmitting slit corresponding to at least one peak position detected by the detecting unit out of the plurality of light transmitting slits on the scale, based on the plurality of peak positions detected by the detecting unit and correction information showing a relation of a distance between a plurality of peak positions in the light-receiving amount distribution on the light-receiving unit and a distance between a plurality of light transmitting slits on the scale which respectively correspond to the plurality of peak positions,
• wherein the light-projecting unit and the light-receiving unit are provided in the casing such that the light-projecting unit, the scale, and the light-receiving unit are arrayed in a direction crossing the one direction.