Abstract: An apparatus of the invention for inspecting bottles for detecting flaws or contamination in the bottles relies upon the light converging function performed by one open-sided elliptic cylinder having reflective inner surface and two foci. The point or line to be inspected of the bottle is positioned at one of the two foci, while at least one light receiving element is disposed at the other focus. A beam of light is applied to the point or line to be inspected of the bottle, so that, if there is any defect such as flaw or contamination, the light is reflected irregularly by the bottle in indefinite direction. The irregularly reflected fractions of light are reflected by the inner surface of the elliptic cylinder and converge on the light receiving element disposed at the other focus, so as to be effectively received by the same element. the presence of the defect, if any, is detected from the output of the light receiving element.

Abstract: A video signal produced by picking up the light image of light projected upon a screen is quantized by a plurality of voltage comparators grouped in pairs and applied with different reference voltage levels. One of the outputs of comparators of respective pairs is inverted in an orderly manner and then synthesized with the rest of the outputs to produce a dark and bright stripe signal which is displayed on a video display device to form a radially discrete annular pattern representative of equibrightness curves.