DISC COVER LAYER MEASUREMENT SYSTEM

摘要

Apparatus (11) and a method for measuring the thickness of a disc cover layer (10) are described. The apparatus (11) and method find particular application for measuring the thickness of a cover layer of a Blu-ray disc® or an Ultra Density Optical (UDO®) disc. A monochromatic light source (12) is employed to generate a fringe pattern on the intensity distribution detected by a light detector (15) following reflection of the light from the disc cover layer (10) . By measuring the frequency of the fringe pattern on the intensity distribution allows for the thickness of the disc cover layer (10) to be calculated. The described apparatus (11) and method therefore provide an optical non-contact measurement of the cover layer (10) of an optical storage disc that is non destructive to the particular disc under test.