When measurements are being made using the red laser EDM, the results can
b
e influenced by objects passing between the EDM and the intended target
surface. This occurs because reflectorless measurements are made to the first
surface returning sufficient energy to allow the measurement to take place. For
example, if the intended target surface is the surface of a building, but a vehi-
cle passes between the EDM and the target surface as the measurement is
triggered, the measurement may be made to the side of the vehicle. The result
is the distance to the vehicle, not to the surface of the building.
If using the long range measurement mode (> 1000 m, > 3300 ft) to prisms,
and an object passes within 30 m of the EDM as the measurement is triggered,
the distance measurement may be similarly effected due to the strength of the
laser signal.
Very short distances can also be measured reflectorless in Prism mo
de to well
reflecting natural targets. The distances are corrected with the additive con-
stant defined for the active reflector.
WARNING
Due to laser safety regulations and measuring accuracy, using the Long Range
R
eflectorless EDM is only allowed to prisms that are more than 1000m (3300ft)
away.
Accurate measurements to prisms should be made in Prism mo
de.
When a distance measurement is triggered, the EDM measures to the object
which is in the b
eam 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
av
oid getting mixed return signals.
Instruments equipped with an ATR sensor permit automatic angle and distance
me
asurements to prisms. The prism is sighted with the optical sight. After ini-
tiating a distance measurement, the instrument sights the prism centre auto-
matically. 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.
Distance
m
easurement
☞
☞
☞
☞
ATR/Lock
Operation 47
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