An apparatus for detecting a shape of a groove, comprises: a device for forming picture images of a groove and a groove face of a work piece of metal to be welded with the use of a welding arc as illuminating light; a storage device for storing information on picture elements of the picture images formed...http://www.google.com/patents/US4988201?utm_source=gb-gplus-sharePatent US4988201 - Apparatus for detecting a shape of a groove
