Patent US 5,200,801

Apparatus for detecting vertical checks in the finish of a translucent container that includes a light source for directing light energy onto the container finish from externally of the container finish laterally of the container axis over an angular portion less than the entire circumference of the container finish. An area array camera is positioned externally of the container at an angle to the container axis so as to receive an image of the illuminated portion of the container finish. The camera is oriented with respect to the light source such that a vertical check in the container finish reflects light energy from the source to the camera to create a bright a image of the check against a normally dark background. Vertical checks in the container finish are detected as a function of such reflected light energy.