Cover Sheets for Dust Protection

Abstract

The problems of dust contamination of an initially clean optical disk can be alleviated by sealing the recording surface beneath a transparent protective layer. Overcoats, transparent substrates, and air-spaced cover sheets can be used to keep small particles out of the focal range of the objective lens and minimize their optical effects. The intrinsic optical properties required by such cover-sheet layers have been described.1 The purpose of this study is to determine the minimum layer thickness (or cover-sheet spacing) necessary to provide reliable optical isolation of dust on the surface of an optical disk.