Theoretical aspects of the calibration of geodetic angle measurement instrumentation

There are multiple instruments directly implementing the principle of angle measurements (horizontal and vertical) for its functioning, used in geodesy, surveying and machine building (like tacheometers, theodolites, laser scanners, laser trackers etc.). As for the moment, there is no official reglamentation regarding calibration and testing of such instrumentation in entire range of the measurements, though instrumentation produce a huge number of both horizontal and vertical angular values during its normal implementation. In the paper the theoretical assumptions of such instrumentation testing and calibration together with examples of some practical tests are given.