A polishing system includes a platen, a carrier head to hold a surface of a substrate against a polishing pad on the platen, a monitoring module including a light source and a detector, an optical fiber having a proximate end coupled to the monitoring module and a distal end, and an optical head removably...http://www.google.es/patents/US7651385?utm_source=gb-gplus-sharePatente US7651385 - Polishing system with optical head
