Patent ID: 6934040

Claim:
Apparatus for determining in situ a reflective characteristic of an area of a surface of an article being processed, comprising: a machine component having a surface adapted to contact said article surface, a window forming a portion of said component surface, at least one source of optical radiation provided on the machine component on a side of the window opposite to the article contacting surface, an optical radiation spreading element carried by the machine component between the window and said at least one source of optical radiation, said element spreading light from said at least one source of optical radiation through the window over an angle of 45 degrees or more, collection optics carried by the machine component in a position to gather optical radiation passing through said window after reflection by the article area, a photo-detector receiving optical radiation from the collection optics to generate an electrical signal related thereto, and a processor utilizing the electrical signal to determine the reflective characteristic of the article area.