FOCUS 35 TOTAL STATION USER GUIDE
4 –
Setup
64
Optical (HA/VA) Collimation and Trunnion Axis Tilt
The Spectra Precision FOCUS 35 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 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 Spectra Precision FOCUS 35
Total Station will always provide accurate measurements.
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 (328 ft).
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 horizontal
and vertical axes. The calibration is used to correct the positions of all points measured using the
LockNGo Tracker function.
Adjustment Routines in Survey Pro software (if available)
Start the application program Spectra Precision Survey Pro software. During the process the
instrument should be on a stable platform.
