In order to measure a thickness of a surface to be polished of a material to be polished for a short time, two-dimensional images are obtained from a light reflected from the surface to be polished of the material to be polished, a location at which a thickness is to be observed is specified by the obtained...http://www.google.de/patents/US6142855?utm_source=gb-gplus-sharePatent US6142855 - Polishing apparatus and polishing method
