Abstract: First and second pairs of mirrors are oriented to intercept first and second regions respectively of a diffraction pattern and deflect these regions to individual detectors so that simultaneous analysis of the regions of the diffraction pattern can be carried out. The pairs of mirrors can be spaced along the optical axis in a manner to provide focused regions of the diffraction pattern at the detectors wherein the diffraction pattern itself is imaged at two spaced focal planes resulting from astigmatic conditions. The physical arrangement not only overcomes problems introduced by astigmatism but also permits practical physical positioning of individual photo-diode arrays such that simultaneous processing of the regions in the diffraction pattern can be carried out.

Abstract: A system is provided for scanning a laser beam across the width of fabric material to be inspected. A scanning mirror receives coherent light from the beam and is mounted to repeatedly swing through a given scan angle. An optical arrangement of mirrors in side-by-side relationship receives the light beam from the scanning mirror and directs it in successive side-by-side parallel directions or channels towards the fabric to irradiate successive areas of the fabric across its width. A de-scanning mirror is mounted to repeatedly swing through the same given scan angle in synchronism with the scanning mirror and a second optical arrangement of mirrors in alignment with the first mentioned mirrors receives the beam after passing through successive areas of the fabric and directs it to the de-scanning mirror. The beam reflected from the de-scanning mirror in turn can then be analyzed.