Precision Spherometer

For measuring plate thicknesses, depressions and the radii of curvature of spherical surfaces such as lenses. The instrument consists of a tripod with three steel tips forming an equilateral triangle, with a micrometer screw and measuring tip recessed in the centre. The micrometer screw carries a disc divided from 0 to 500, and a vertical scale on the tripod reads in millimetres from -10 to 15 mm.