SURFACE DETECTION METHOD FOR STEEL PLATE HAVING RESIN COATING FILM AND SURFACE DETECTION DEVICE FOR SAME

摘要

A surface inspection method according to the present invention, for a steel sheet coated with a resin, includes the steps of: irradiating the steel sheet with sheet-like light, which has been linearly polarized at a predetermined polarization angle, at an incidence angle different from Brewster's angle of the coating by a predetermined angle or greater; and imaging linearly-polarized light of a polarization angle of 0 degrees at an acceptance angle different from a regular reflection angle of incident light by a predetermined angle. Accordingly, it is not necessary to change the incidence angle and the acceptance angle depending on resin components and it is possible to inspect substrate steel surface of the steel sheet highly accurately without observing abnormalities in the coating itself.