System Software Testing of Laser Tracker Leica AT401

The article introduces a group of instruments called laser trackers and specificallyfocuses on one of them - Leica AT401. At the Research Institute of Geodesy, To-pography and Cartography the instrument has been tested both in laboratory andoutdoor conditions. Several significant errors in the instrument’s system softwarehave been found, mostly due to the creation of user-programmed controlling appli-cation called ATControl. The errors are related to a selection, a computation andan evaluation procedure of the refractive index of air. Finally, notes of the newmeasurement modes of Leica AT40x are given and a range of distance measure-ment is discussed.