Method and apparatus for edge detection of transparent films

Abstract

A method for detection of the edge and/or shape of transparent films, wherein the incident rays from a light source enter a polarizer to yield the linearly polarized light for irradiation to a transparent film with a property of rotatory polarization, and the rotatorily polarized light therefrom is transmitted through an analyzer with a polarization axis orthogonal to that of the polarizer, allowing the transmitted light to indicate the edge position and/or shape of the transparent film. An apparatus for detection of the edge and/or shape of transparent films, which is furnished with a polarizer, analyzer and detector to utilize the property of rotatory polarization of a transparent film placed between the polarizer and the analyzer, wherein the polarizer linearly polarizes the incident rays from a light source, emitting the light to be fed to the analyzer, a polarization axis of which is orthogonal to that of the polarizer, and the detector recognizes the output of the analyzer.

Dependencies are inferred from the claim text.