| 摘要 |
A magneto-optical disc is prepared having substrates made from polycarbonate, on which recording layers are formed to serve as signal recording medium sections facing each other via a spacer. The magneto-optical disc is also provided with a clamp portion formed in such a way that when the magneto-optical disc is mounted on an optical disc recording and/or reproduction apparatus having an objective lens with a focal distance L0 the recording layer is positioned at a distance L1 which is equal to a focal distance of the objective lens obtained in the substrate via refraction.
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