Patent ID: 6538730
Filing Date: 2003-03-25
Classification: G01N

Abstract:
A surface inspection method for detecting anomalies on a surface, comprising:causing the surface to be scanned by a beam of radiation; collecting radiation scattered from the surface by means of a collector that collects the scattered radiation substantially symmetrically about a line normal to the surface; directing the collected radiation to channels at different azimuthal angles about the line or about a direction corresponding thereto so that information related to relative azimuthal positions of the collected radiation about the line is preserved and radiation scattered by the surface at different azimuthal angles with respect to the line is conveyed along different channels, said directing comprising separating the channels from each other by separators to reduce crosstalk; converting the collected radiation carried by at least some of the channels into respective signals representative of radiation scattered at different azimuthal angles about the line; and determining the presence and/or characteristics of anomalies in or on the surface from said signals.