Spectra Precision Focus 30, User Manual

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Spectra Precision FOCUS 30 User Guide 53
4 Setup
Optical (HA/VA) Collimation and Trunnion Axis Tilt
The Spectra Precision FOCUS 30 Total Station instrument utilizes precise angle and
distance measurements to determine the position of the point being measured. The
instrument’s design facilitates the ability to measure all points with a single pointing
to the target in the Face1 position. All electronic total stations are subject to collima-
tion 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 cor-
rections to be applied to all measurements made in a single pointing to a target. In this
way the Spectra Precision FOCUS 30 Total Station will always provide accurate mea-
surements
The adjustment of the instrument for HA/VA collimation and Trunnion Axis tilt is a
two stage process.
LockNGo Tracker
Only on Instruments with LockNGo capability:
The LockNGo Tracker unit is designed to be coaxial with the instrument cross hairs.
If for any reason the alignment of the tracker deviates from the line of the telescope
cross hairs, then errors in position of the point being measured would result. For this
reason an LockNGo collimation check needs to be carried out on a regular basis to
ensure that any slight misalignment is corrected for. Perform the test over a similar
distance as that you will be working on, but at least 100 m. The prism target must be
very still during the test (Spectra Precision recommends that you use a tripod or bipod
mount for the target) and must be in clear line of sight without any obstructing traffic.
The instrument is calibrated to accurately point at the center of the target in both hor-
izontal and vertical axes. The calibration is used to correct the positions of all points
measured using the LockNGo Tracker function.