Abstract: The degree to which a rotating object like a machine tool spindle undesirably wobbles in directions both transverse and parallel to its axis of rotation is measured preferably by providing a laser beam or other beam energy source which directs the beam toward a beam reflecting surface, most advantageously a curved surface, like a spherical or cylindrical surface. The reflecting surface is most advantageously formed by a spherical body mounted for adjustment in a plane perpendicular to the rotating axis involved, so that the center of the curved surface can be positioned as close as possible to the axis involved before error measurements are taken. In such case, the distance the beam traverses between the beam source and the point on the curved surface struck by the beam is a measure of the degree to which the spindle undesirably wobbles in directions both transverse to and parallel to the spindle axis.

Abstract: A method of obtaining by use of a laser measuring apparatus position measurement error information of a body to be moved under computer control in a volumetric space along paths having designated measuring points for position error evaluation or correction. The method in a preferred form includes the steps of directing a laser beam in a given direction in said space and placing a laser beam reflector on the body to be moved in directions non-parallel to said direction, the reflector being sufficiently large that it will receive and reflect said directed laser beam back to said apparatus for actual reflector distance measurement along the beam path as said body is so moved. Then, with the computer of said system moving said body along said non-parallel paths measuring and recording with said apparatus the actual positions of said reflector along said beam path as the body reaches said various measuring points.

Abstract: The degree of accuracy a machine tool or the like is moved along a given path is determined by a unique preferably laser beam directing measuring system directing simultaneously or in sequence a laser beam parallel to the orthogonal axes of the two or three dimensional space in which the spindle or other object is to be moved in a path which can diverge appreciably in directions other than the directions of these axes. The beam directing means includes means which provides a measure of the actual positions the object has at various sampling times relative to the axis along which the beam is directed. This actual path position data is compared to the desired path position data used to program the object moving machine to determine the path position error at the sampling times involved.

Abstract: A Michelson-type self-aligning interferometer utilizes a laser to produce an output beam of light that is split into signal and reference beams. The signal beam is directed through a Bragg-cell, for heterodyne detection, and a beam expander, for facilitating target acquisition, toward a retroreflector located on a target body. The signal beam is thereby reflected back through the beam expander and Bragg-cell toward the resonance mirror of the laser, and is now shifted in frequency by 2.OMEGA.. The returning signal beam remains co-linear with the output beam since it returns over the same path and through the same optical elements, especially the laser resonance mirror. Thus, the interferometer can accommodate a significant amount of component misalignment without loss of operation. The signal beam, once reflected from the resonance mirror of the laser and partially reflected by the beam splitter, is co-linear with the reference beam.