What is Boresight?

Boresight (or boresight error) is a measure of the deviation (alignment error) of the line of sight with respect to the mechanical axis of the system. This value is generally expressed as an angle. A typical requirement is something like 3 mrad (~0.17°). In order to measure the boresight, a reference plane representing the mechanical axis must be aligned with the target axis before measuring the angular deviation between both axes.

Boresight