Enhanced position detector in laser tracker

A device sends a first light beam to a target which returns a portion of the first beam as a second beam. First and second motors direct the first light beam to a first direction determined by first and second angles of rotation about first and second axes. First and second angle measuring devices measure first and second angles of rotation. A distance meter measures a first distance between device and target. A second portion of the second beam passes through a diffuser and onto a position detector which produces a first signal in response. A control system sends a second signal to the first motor and a third signal to the second motor, the second and third signals based on the first signal. The control system adjusts the first direction of the first beam to the target position. A processor provides a 3D coordinate of the target.