| 摘要 |
A read-only optical registration medium which successively includes: a transparent substrate; a first registration surface containing localized level variations representing binary data bits; a protective layer, whereby: between the substrate and the first registration surface, the medium further includes a dielectric trilayer which contains a first, second and third dielectric layer having respective refractive indices n1, n2 and n3, whereby, at both a first wavelength lambda 1 and a second wavelength lambda 2: n2<n1 and n2<n3, the trilayer being constituted so as to be transparent at lambda 1 and to be semi-reflective at lambda 2; the surface of the trilayer nearest the substrate contains localized level variations representing binary data bits, thereby forming a second registration surface. An alternative registration medium according to the invention successively includes: a substrate (4); a first registration surface containing localized level variations representing binary data bits; a transparent protective layer, whereby: between the protective layer and the first registration surface, the medium further includes a dielectric trilayer which contains a first, second and third dielectric layer having respective refractive indices n1, n2 and n3, whereby, at both a first wavelength lambda 1 and a second wavelength lambda 2: n2<n1 and n2<n3, the trilayer being constituted so as to be transparent at lambda 1 and to be semi-reflective at lambda 2; the surface of the trilayer nearest the protective layer contains Iocalized level variations representing binary data bits, thereby forming a second registration surface.
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