Product Manual

40
HA/VA Collimation and Trunnion Axis Tilt
The instrument utilizes precise angle and distance
measurements to determine the position of the point being
measured. The instruments design facilitates the ability to
measure all points with a single pointing to the target in the
face 1 position. All electronic total stations are subject to
collimation errors in both the horizontal and vertical angle
measuring systems, and also errors caused by the axis of the
telescope not being truly perpendicular to the vertical of the
instrument.
In order to compensate for these errors, the collimation
routine allows the operator to accurately determine the
current errors in the instrument, and store the errors as
corrections to be applied to all measurements made in a single
pointing to a target. In this way the instrument will always
provide accurate measurements:
The Collimation errors and Trunnion axis tilt will change over
time, the most common changes being caused by
• Wear and tear with use
• Bumps and knocks during transit
• Large changes in operating temperature
Spectra Geospatial recommends that a collimation check and
tilt axis check be carried out routinely as follows:
• After any long uncontrolled transport of the instrument
(e.g. after service or shipment to a new location)
• After any accidental knock or drop
• At any time when the operating temperature changes by
more than 10 °C (18 °F)
• At any time when the instrument changes it's height above
sea level by more than 500 m (1,640 ft)
• At any time when the highest accuracy positions are
required for single pointing to a target (not two face
measurements)
• Routinely on a periodic basis (monthly, weekly etc.)
Spectra Geospatial also recommends that the operator keep a
record of the dates and values measured so that any gross
changes can easily be detected. Gross changes can indicate
the need for a check by an approved service center.
The adjustment of the instrument for HA/VA collimation and
Trunnion Axis tilt is a two-stage process.