Importance

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Abstract

A tubular illuminator for focusing a bright line of approximately specular illumination onto the surface of a web moving at high speed to detect defects usually in the surface of the web. The illuminator in one embodiment comprises an elongated glass cylinder having reflective Fresnel ring facets or grooves on the major portion of the interior surface thereof extending the length of the glass tube, an elongated cylindrical lens assembly positioned inside the elongated tube adjacent and interior surface thereof devoid of the fresnel grooves, a mirror surfaced lens assembly housing for positioning the elongated lens assembly within the elongated cylinder in relation to an elongated slit diffuser extending axially through substantially the entire length of the glass cylinder, and an elongated line lamp disposed within the cylinder and extending in parallel to the diffuser-slit, so that light emitted by the elongated lamp is specularly reflected by mirror surfaces as reflective Fresnel facets and is directed or focused onto diffuser-slit and refocused by the lens assembly as bright line illumination or scanning an adjacent moving web surface.

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First Claim