| 摘要 |
An optical disc comprising a substrate and a recording layer and a light-transmitting layer, laid on a substrate one upon the other in the order mentioned. A light beam is applied to the recording layer through the light-transmitting layer, to record and/or reproduce data on the disc. The light-transmitting layer is composed of at least two material layers laid one on the other and having different refractive indices. The disc is designed to set the spherical aberration caused by an objective lens that focuses the light beam used to record and/or reproduce data, at a value close to a minimum. <IMAGE>
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