Spectra Precision Focus 30, Руководство пользователя

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Spectra Precision FOCUS 30 User Guide 75
6 Instrument Technology
Correction for Collimation Errors
HA/VA Collimation
The horizontal collimation error is the deviation of the sighting axis from its required
position at right angles to trunnion axis.
The vertical collimation error is the difference between the vertical circle zero and the
plumb axis of the instrument.
Traditionally, collimation errors were eliminated by observing angles in both instru-
ment faces. In the Spectra Precision FOCUS 30 Total Station, a pre-measurement col-
limation test is performed to determine the collimation errors. Angular measurements
are observed in both instrument faces, the collimation errors are calculated, and the
respective correction values are stored in the instrument. The collimation correction
values are then applied to all subsequent angle measurements, including the distance
related focus lens collimation error. Angles observed in a single face are corrected for
collimation errors, which eliminates the need to measure in both instrument faces.
Carry out a collimation test in the following situations:
• Whenever the instrument may have been roughly handled during transport.
• When the ambient temperature differs by more than 10°C (18°F) from the
previous collimation test.
• Immediately prior to high precision angle measurements in one face.
Spectra Precision FOCUS 30 Total Station with LockNGo Tracker
A Spectra Precision FOCUS 30 Total Station with LockNGo capability can automati-
cally lock and track a prism target as it moves. Pointing errors caused by slight mis-
alignment of the instrument’s tracker have a similar effect to the HA and VA
Collimation errors as detailed above.
To correct for the tracker collimation errors, carry out a LockNGo Tracker collima-
tion test. The LockNGo Tracker collimation test automatically observes angular mea-
surements to a target in both faces, the tracker collimation errors are calculated and
the respective correction values are stored in the instrument.
The collimation correction values are then applied to all subsequent angle measure-
ments observed when LockNGo Tracker is enabled. Angles observed in a single face
are corrected for collimation errors, which removes the need to measure in both
instrument faces.
Carry out a LockNGo Tracker collimation test in the following situations:
• Whenever the instrument may have been roughly handled during transport.
• When the ambient temperature differs by more than 10°C (18°F) from the
previous collimation test.
• Immediately prior to high precision angle measurements in one face.