Tolerance of a laser reflectorless EDM instrument

Results of experiments with a laser reflectorless EDM instrument to test its tolerance are reported. Field distance measurements were simulated with measurements to >50 targets, identified with various surfaces, mostly not planar or normal to the sighting axis of instrument. Measured distances, covering the full nominal range of the instrument used, are characterized by systematic errors in the form of fluctuations with a maximum value up to 140mm at the distance of 20m, attenuating at longer distances. It was also found that the colour of target surfaces controls the maximum range of measurements, and some surface such as common mirror lead to erroneous results. Conclusions of our study are broadly consistent with conclusions of experiments with laser scanners.