Measuring device for contactless testing of external threads - compares diffraction patterns, with standard pattern in form of diaphragm system

摘要

External thread for contactless testing is placed in the path of a beam from a sufficiently monochromatic light source (1), so that diffraction patterns produced by the tested external thread and a standard thread are superposed at a sufficient distance from the diffracting object (3). Diffraction pattern of the standard is in the form of a diaphragm system (7) pref. produced by photographic means using the same equipment. Radiation receivers behind, or at, the focal plane (5), connected to an electronic circuit, compare the diffraction patterns, and, owing to their direct relation to the threads the threads themselves.