Abstract: A mounting system for mounting an optical element to a supporting unit of an optical system that may include several optical elements in a predetermined alignment with respect to one another and with respect to an optical axis. A carrier holding an optical element in a known position and orientation with respect to the carrier is attached to a supporting unit in a selected location and position of rotation, with respect to an axis that may be the optical axis, by a plurality of magnetic elements, ones of which are carried in or affixed to the supporting unit in predetermined locations and orientations, and other ones of which are included in or affixed to the carrier in predetermined locations and orientations that result in mutual attraction between corresponding ones of the magnetic elements when the carrier is in a predetermined position with respect to the supporting unit.

Abstract: Apparatus for real time measurement of optical beam parameters includes an assembly of known dimensions, carrying multiple apertures, occupying parallel planes. The assembly can be moved so that the apertures sequentially intersect an optical beam which is not propagated in the plane of the apertures. At least one pair of the apertures are non-circular and identical with accurately established positions and which are not disposed in the same angular alignment when they intercept the beam but are disposed in the same plane in order to allow determination of the two-dimensional position of the centroid of the beam in that plane.