a defect inspection for the investigation of defects on an optical disk.

摘要

A defect inspecting apparatus for inspecting defects in an optical type disc comprises a motor (11) for rotating an optical type disc (10) which is to be inspected, a light beam generator (13) for generating a light beam, a lens system (14, 15) for irradiating the light beam generated from the light beam generator on a signal recording range (28) of the disc over a predetermined range, an image sensor (18) for subjecting a light beam reflected from a signal recording surface (21) of the disc to a photoelectric conversion, and a detecting circuit (41-47) for detecting a change in an output signal level of the image sensor so as to detect the existence of defects in the disc. The lens system converts the light beam generated from the light beam generator into a light beam having a cross section of a predetermined shape so that an irradiated part (30) on the disc extends in a radial direction of the disc, and the length of the irradiated part in the radial direction of the disc is at least slightly greater than the width of the signal recording range in the radial direction of the disc.