Abstract: A volumetric error compensation measurement system and method are disclosed wherein a laser tracker tracks an active target as the reference point. The active target has an optical retroreflector mounted at the center of two motorized gimbals to provide full 360 degree azimuth rotation of the retroreflector. A position sensitive detector is placed behind an aperture provided at the apex of the retroreflector to detect the relative orientation between the tracker laser beam and the retroreflector by measuring a small portion of the laser beam transmitted through the aperture. The detector's output is used as the feedback for the servo motors to drive the gimbals to maintain the retroreflector facing the tracker laser beam at all times. The gimbals are designed and the position of the retroreflector controlled such that the laser tracker always tracks to a pre-defined single point in the active target, which does not move in space when the gimbals and/or the retroreflector makes pure rotations.

Abstract: A volumetric error compensation measurement system and method are disclosed wherein a laser tracker tracks an active target as the reference point. The active target has an optical retroreflector mounted at the center of two motorized gimbals to provide full 360 degree azimuth rotation of the retroreflector. A position sensitive detector is placed behind an aperture provided at the apex of the retroreflector to detect the relative orientation between the tracker laser beam and the retroreflector by measuring a small portion of the laser beam transmitted through the aperture. The detector's output is used as the feedback for the servo motors to drive the gimbals to maintain the retroreflector facing the tracker laser beam at all times. The gimbals are designed and the position of the retroreflector controlled such that the laser tracker always tracks to a pre-defined single point in the active target, which does not move in space when the gimbals and/or the retroreflector makes pure rotations.

Abstract: An optical measurement system increases the number of translational and angular measurements made with a single laser beam by combining an optical interferometer with an optical autocollimator. Translational measurements are made with an optical interferometer and yaw and pitch measurements are made with an autocollimator. In a preferred embodiment, angular deviations in the reflected measuring beam are minimized with a reverse telescopic lens assembly, allowing a wider range of angular measurements without significant degradation of interferometer accuracy.

Abstract: An optical measurement system increases the number of translational and angular measurements made with a single laser beam by combining an optical interferometer with an optical autocollimator. Translational measurements are made with an optical interferometer and yaw and pitch measurements are made with an autocollimator. In a preferred embodiment, angular deviations in the reflected measuring beam are minimized with a reverse telescopic lens assembly, allowing a wider range of angular measurements without significant degradation of interferometer accuracy.