Raster cutting technology for ophthalmic lenses
AssigneeEssilor International (Compagnie Generale d'Optique)
InventorsJames Daniel Riall, Walter Dannhardt, Roland Mandler, Tobias Müller
Life of this patent
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Abstract
A raster cutting apparatus and method for producing accurately formed, aspheric ophthalmic lenses having a good quality surface finish. The accurate form and good surface finish are obtained by using a substantially spherically shaped cutting tool having a large radius. The methods include utilizing a cutting path which provides substantially constant cutting-force, such as a constant surface-cutting-speed raster pattern.
Claims28
A method of forming a three-dimensional surface on a workpiece, comprising:
- providing a spindle having a spindle axis;
- providing a cutting tool having a substantially spherical cutting surface;
- rotating said cutting tool about said spindle axis;
- and
- moving said cutting tool in a raster cutting pattern relative to the surface being formed, wherein the effective cutting radius of the point of contact between the cutting surface and the three-dimensional surface varies along the cutting pattern.
An apparatus for forming a three-dimensional surface, comprising:
- a spindle having a spindle axis;
- a cutting tool having a substantially spherical cuffing surface;
- a support stage for holding a work-piece and capable of controlled three-dimensional motion relative to said cutting tool;
- a control module capable of calculating a cutting path comprising a raster pattern such that the effective cutting radius of the point of contact between the cutting surface and the three-dimensional surface varies along the raster pattern.
A machine-readable medium embodying a computer program for causing a computing system to:
- control three-dimensional motion of a support stage for holding a work-piece relative to a cutting tool;
- and
- calculate a cutting path for said cutting tool, said cutting tool having a substantially spherical cutting surface, the cutting path comprising a raster pattern, and wherein the effective cutting radius of the point of contact between the cutting surface and the work-piece varies along the raster pattern.
A method comprising:
- determining control information for controlling a rotating cutting tool for forming a three-dimensional surface on a work-piece, the cutting tool having an arcuate cutting surface with a varying cutting radius that varies along an axis of rotation of the cutting tool, wherein determining the control information includes
- determining a trajectory of the cutting tool relative to the work-piece such that points of contact between the cutting surface and the three-dimensional surface form a desired path along the three-dimensional surface, wherein the effective cutting radius of the point of contact on the cutting surface varies along the desired path, wherein the desired path comprises a raster pattern.
Dependencies are inferred from the claim text.