Calibrating an absolute distance meter (ADM) laser tracker requires long linear distances. For such distances, the room temperature is a significant factor. Even though the calibration room’s temperature is controlled within ± 2° C, actual temperature and temperature variation in one end of the room can be different from another because of uneven airflow in the room.

Controlling the air temperature and air flow along the rail can be costly for a laboratory. Thermally compensating the ADM distance for a laser traveling over a range of 50 m is not easy with just one temperature sensor. On the other hand, multiple temperature sensors placed along the ADM beam path further complicates ADM distance error compensation.