FlexLine plus, Check & Adjust
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14.3 Adjusting Line-of-Sight and Vertical Index Error
Line-of-sight error The line-of-sight error, or horizontal collimation error is the deviation from the
perpendicular between the tilting axis and the line of sight. The effect of the line-of-
sight error to the horizontal direction increases with the vertical angle.
Vertical index error The vertical circle should read exactly 90° (100 gon) when the line of sight is hori-
zontal. Any deviation from this figure is termed vertical index error. This is a constant
error that affects all vertical angle readings.
Access 1) Select Tools from the Main Menu.
2) Select Adjust from the Tools Menu.
•Select:
• Hz-Collimation, or
• Vertical Index.
The procedures and conditions required to correct line-of-sight and vertical index
errors are the same, therefore the procedure will only be described once.
a) Tilting axis
b) Line perpendicular to tilting axis
c) Horizontal collimation, or line-of-sight, error
d) Line-of-sight
a
b
d
c
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a) Mechanical vertical axis of the instrument, also called
standing axis
b) Axis perpendicular to the vertical axis. True 90°
c) Vertical angle is reading 90°
d) Vertical index error
By determining the vertical index error the electronic
level is adjusted automatically
b
c
d
a
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