Very short distances may be measured reflectorless in IR mode to well reflecting targets. Note that the distances are corrected with the additive constant defined for the active reflector.
Distance measurement
Accurate measurements to prisms should not be made in reflectorless mode.
When a distance measurement is triggered, the EDM measures to the object which is in the beam path at that moment. If a temporary obstruction, for example a passing vehicle, heavy rain, fog or snow is between the instrument and the point to be measured, the EDM may measure to the obstruction.
Do not measure with two instruments to the same target simultaneously to avoid getting mixed return signals.
ATR/lock
Instruments equipped with an ATR sensor permit automatic angle and distance measurements to prisms. The prism is sighted with the optical sight. After initiating a distance measurement, the instrument sights the prism centre automatically. Vertical and horizontal angles and the distance are measured to the centre of the prism. The lock mode enables the instrument to follow a moving prism.
As with all other instrument errors, the collimation error of the automatic target recognition must be redetermined periodically. Refer to the GeoPad/Site Foreman manual about checking and adjusting instruments.
If the prism location is changed too quickly, the target may be lost. Make sure that the speed does not exceed the figure given in the technical data.
Due to laser safety regulations and measuring accuracy, using the Long Range Reflectorless EDM is only allowed to prisms that are more than 1000 m (3300 ft) away.