Patent US 6,469,784

Method and apparatus for optical inspection of an article are presented. The apparatus comprises an illumination unit and at least one detection unit. The illumination unit generates an incident beam and directs it onto a predetermined region of the article. The detection unit includes a light collection system and a detector. The light collection system collects light scattered from the illuminated region with a predetermined constant maximum collection angle, and utilizes a variable angle design for selectively selecting from collected light at least one light component propagating with a solid angle segment of the maximum collection angle, and directing it to the detector.