collimation : Idioms & Phrases
Error of collimation
- the deviation of the line collimation of an astronomical instrument from the position it ought to have with respect to the axis of motion of the instrument.
Webster 1913
Line of collimation
- the axial line of the telescope of an astronomical or geodetic instrument, or the line which passes through the optical center of the object glass and the intersection of the cross wires at its focus.