Automatic vertometer for spherical ophthalmic lenses

A vertometer for spherical ophthalmic lenses was designed that is automated in focusing a target, in centering a lens being tested, and in marking its center within specified limits of tolerances. Light from the target is introduced into a scanning unit that detects the three-dimensional deviation of its image from a desired position and generates three signals to drive simultaneously the target and the lens so that the image of the target may come to the desired position. This procedure is followed by an automatic measurement of the deviation and marking the center, with an accuracy some five times greater than is attainable by visual examination. The working principle and experimental results are described in detail.