Position detecting device and inclination sensor device of surveying apparatus using the same, and position measuring method

摘要

A position detecting device includes: a liquid (7) having a free surface (7a); a light source (2) configured to irradiate a light flux toward the free surface (7a) of the liquid (7); a dark field pattern (4) provided between the liquid (7) and the light source (2) and configured to form a pattern of the light flux irradiated by the light source (2); a light-receiving sensor (9) configured to detect the pattern of the light flux reflected by the free surface (7a) of the liquid (7); and an arithmetic unit (11) configured to calculate a position of the pattern from results of detection of the light-receiving sensor (9), wherein the arithmetic unit (11) is configured to add the results of the detection of the light-receiving sensor (9) in an X-direction and a Y-direction of the light-receiving sensor (9), and the arithmetic unit (11) is configured to calculate the position of the pattern from an output obtained by adding the results of the detection in the X-direction and the Y-direction.