Continuous feed holographic correlator for randomly oriented workpieces

摘要

A method and apparatus to optically control mass produced articles by a holographic correlator. The articles are continuously moved through an input beam of the holographic correlator. The correlator employs a holographic filter having a plurality of Fourier spectra recorded thereon, which are spatially separated but overlapping and which correspond to different orientations of the reference specimen. During the translation of the object through the input beam, the beam is reflected so that all spectra are addressed through the holographic filter. The output correlation spot is detected through a diaphragm having a slit-form aperture. This apparatus and the method it employs does not depend on the orientation between the article and the holographic filter, thereby providing accurate results at high speeds.