Apparatus for controlling lathed contact lens thickness

Claim 1

A contact lens lathing machine for generating a vision surface on a contact lens at a machine cut position, comprising: a rotatable spindle for carrying a contact lens workpiece having a work surface disposed for lathing; a lathe tool for cutting the contact lens workpiece when disposed at the machine cut position at the lens work surface to generate a vision surface of predetermined curvature for a lens of predetermined thickness; a transducer including a stationary, nonelectrically conductive first subassembly having an electrical contact and a movable, electrically conductive second subassembly having an electrical contact, the second subassembly being slidably received within the first subassembly, the contact of said first subassembly being electrically engaged to said second subassembly when said contact of said second subassembly is in a first position to provide an electrical path, the contact of said second subassembly moved to a second position and the transducer providing an electrical response by movement of the second subassembly relative to the first subassembly imparted by the physical interference between the second subassembly and the work surface of the contact lens workpiece; measuring means mounted to the stationary first subassembly for engaging and measuring movement of the second subassembly upon contact between the worksurface of the contact lens workpiece and the second subassembly and a controller responsive to the electrical response provided by the transducer for registering the physical interference location relative to the cut position to generate control signals for disposing the lathe tool with respect to the contact lens workpiece for generating, as a function of the electrical response, a vision surface of predetermined curvature for a lens of predetermined thickness.