In the peripheral surface defective detection optical system of the glass disk and the peripheral surface defective

摘要

PROBLEM TO BE SOLVED: To provide an optical system for detecting peripheral surface defects of a glass disk and a device of detecting the peripheral surface defects, which can detect the peripheral surface defects, such as flaws or cracks due to a chuck used for the glass disk with high accuracy, without hardly detecting foreign matters which is one of the defects.;SOLUTION: In the optical system, since light beams are projected from the back face of the glass disk through the glass disk onto the outer peripheral chamfered portion on the front face side of the glass disk, a difference between extinction amounts of the received lights at the foreign matters and at the flaws is increased, whereby a light receiving signal for generating a defect detection signal, corresponding to this difference is obtained.;COPYRIGHT: (C)2008,JPO&INPIT