Automatic machine for grinding and faceting ophthalmic lenses - has sensor to detect relative axial distance between apex of lens and edge of top surface

The machine for grinding and facetting lenses has a saddle (1) carrying the two part shaft (2) which holds the lens (3), rotated by motor (M). The saddle is adjacent to the grinding wheels (4) on a parallel motor-driven shaft (5) and the saddle can slide sideways relative to the grinding wheel. The mounting for the grinding wheels can move in or out relative to the saddle. There is a sensor (18), e.g. in form of electric rheostat potentiometer, to measure the axial distance between the apex of the lens and the edge of the top surface with electronics (13, 14, 15) to give signals to control saddle movement. A sensor (6) gives instantaneous data on angular position of the double shaft and hence, the lens. ADVANTAGE - Measurement of concavity of lens is especially simple.