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Two large lenses are visible in the laser module. These are the transmitting and receiving optics. The infrared
measuring laser is fired through the transmitting optics. Its reflected light is then received back into the instrument
through the receiving optics. A smaller window protects the visible red dot laser pointer which can be switched on
to assist tracking of the VS+ distance measurement laser. The pathway of the visible and infrared lasers is co-linear,
but not co-axial.
3.3 Yoke and horizontal housing
The yoke which holds the laser module contains the vertical motor. This motor drives the vertical rotation of the
laser module between the pillars of the yoke. The yoke also houses the vertical encoder which measures the angle
through which the laser is rotated.
The yoke is attached to the horizontal housing. The horizontal housing contains the horizontal motor which drives
the rotational movement of the yoke. The horizontal housing also houses the horizontal encoder which measures
the angle through which the yoke is rotated.
The combination of the two axes of rotation gives the VS+ a view encompassing 360° horizontal and 270° vertical
rotations respectively. The yoke itself prevents the laser from viewing a 90° sector of the vertical rotational sweep.
Both motors are protected with clutches. This means that if the unit is rotated by hand or
prevented from moving by an obstruction, the motors will not be damaged. It is advisable,
however, to minimise any manual movement of the unit and to keep the instrument away from
potential obstructions so the motors may turn freely. Nevertheless, the possibility of finger or
clothing entrapment exists. Users should not obstruct the operation of the motors or allow
clothing to come into contact with the device.
Accelerometers are also contained within the horizontal housing. These sensors automatically record the inclination
and roll of the VS+. This ensures that all scans are correctly levelled in
Carlson Scan
software. Information from
the accelerometers, when combined with coordinate and heading information, helps to georeference the scan.
Red dot pointer
Transmitting
optics
Receiving optics
Figure 3 The VS+ laser module
