Alcon Inc.
METHOD FOR THE INSPECTION OF AN OPHTHALMIC LENS FOR SEMI-OPAQUE DEFECTS

Abstract:

A method for inspecting an ophthalmic lens for the presence of an unacceptable semi-opaque defect in a lens body thereof comprises the steps of: illuminating the lens body with laser light in an area bounded by an edge of the lens body; detecting the intensity of laser light scattered by the illuminated lens body in a predetermined detection direction which is different from a direction of reflection; comparing the detected intensity of the scattered laser light with a predetermined threshold intensity; determining a size of at least one coherent area in which the detected intensity of the scattered laser light is higher than the predetermined threshold intensity; determining whether the size of the at least one coherent area is larger than a predetermined threshold size, and rejecting the ophthalmic lens in case the size of the at least one coherent area is larger than the predetermined threshold size.