DETERMINING AN INTERNAL CALIBRATION REFERENCE FOR A TOTAL STATION

The present inventive concept relates to a total station (), a calibration method () for a total station, and a method () for determining an internal calibration reference for a total station. The method () comprises: determining (S) an alignment error of an optical axis (, , ) of a reference measurement channel relative to the sighting axis () of the total station (), wherein the reference measurement channel is a measurement channel () comprising the light source or a measurement channel (, ) comprising the image sensor; rotating (S) the sighting axis () of the total station () about the rotation point to a predetermined position at which a light beam emitted from the light source exits the center unit () via an objective () of the center unit () and, after reflection at a reflective optical element () fixedly coupled to the alidade (), enters the center unit () via the objective () for propagation towards the image sensor; emitting (S) a light beam from the light source; capturing (S) an image with the image sensor; identifying (S) a position of the light beam in the image; and determining (S) an internal calibration reference of the total station () based on the determined alignment error of the optical axis (, , ) of the reference measurement channel and the identified position of the light beam in the image.