Multilayer optical recording medium

Abstract

A multilayer optical recording medium is provided with a totally reflective first information layer provided on a substrate and a second information layer being a translucent information layer provided via a spacer layer. The second information layer is composed of a TiO2 layer, a first dielectric layer, a reflective film, a second dielectric layer, a recording film, and a third dielectric layer, all of which are laminated together in this order. The first dielectric layer is made of ZrO2, Cr2O3, and Al2O3, and has a refractive index in the range of 1.84 to 2.20. If the recoding film is made of a material containing Sb as a main component, it is possible to strike a balance between high values of both the transmittance and the degree of modulation in recording information by laser light with a wavelength of 405 nm using an optical recording system having an optical system with a numerical aperture NA=0.85.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view schematically showing a multilayer optical recording medium according to a first exemplary embodiment of the present invention;

FIG. 2 is a ternary drawing showing the relationship of the composition ratio among ZrO₂, Cr₂O₃, and Al₂O₃ composing a first electric layer according to the first exemplary embodiment;

FIG. 3 is a graph showing the relationship among a refractive index, transmittance, and a degree of modulation in a translucent information layer;

FIG. 4 is a graph showing the relationship between a composition ratio and an optical constant in the case where Cr₂O₃:Al₂O₃ of the first dielectric layer is made in accordance with the first exemplary embodiment;

FIG. 5 is a graph showing the relationship among the thickness, transmittance, and degree of modulation of the first dielectric layer according to the first exemplary embodiment; and

FIG. 6 is a sectional view schematically showing a multilayer optical recording medium according to a second exemplary embodiment of the present invention.

Claims

1. A multilayer optical recording medium comprising: a substrate; a first information layer provided on the substrate; at least one translucent information layer provided on the first information layer; and a spacer layer provided between the information layers, recording laser light being incident on the multilayer optical recording medium from a side away from the substrate, wherein the at least one translucent information layer comprises a TiO2 layer, a first dielectric layer, a second dielectric layer, a recording film having Sb as a main component, and a third dielectric layer, all of which are laminated in this order, and the first dielectric layer is made of ZrO2, Cr2O3, and Al2O3 and has a refractive index in a range of 1.84 to 2.20.

2. The multilayer optical recording medium according to claim 1, comprising a translucent reflective film positioned between the first dielectric layer and the second dielectric layer.

3. The multilayer optical recording medium according to claim 1, wherein the first dielectric layer has an extinction coefficient in a range of 0.1 or less.

4. The multilayer optical recording medium according to claim 2, wherein the first dielectric layer has an extinction coefficient in a range of 0.1 or less.

5. The multilayer optical recording medium according to claim 1, wherein in the first dielectric layer the composition of ZrO2:Cr2O3:Al2O3 is in a range of ratios of (70:10:20), (10:50:40), (10:20:70), or (20:10:70) mol %.

6. The multilayer optical recording medium according to claim 2, wherein in the first dielectric layer the composition of ZrO2:Cr2O3:Al2O3 is in a range of ratios of (70:10:20), (10:50:40), (10:20:70), or (20:10:70) mol %.

7. The multilayer optical recording medium according to claim 3, wherein in the first dielectric layer the composition of ZrO2:Cr2O3:Al2O3 is in a range of ratios of (70:10:20), (10:50:40), (10:20:70), or (20:10:70) mol %.

8. The multilayer optical recording medium according to claim 1, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm or in a range of 100 nm to 120 nm.

9. The multilayer optical recording medium according to claim 2, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm or in a range of 100 nm to 120 nm.

10. The multilayer optical recording medium according to claim 3, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm or in a range of 100 nm to 120 nm.

11. The multilayer optical recording medium according to claim 5, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm or in a range of 100 nm to 120 nm.

12. The multilayer optical recording medium according to claim 1, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm.

13. The multilayer optical recording medium according to claim 2, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm.

14. The multilayer optical recording medium according to claim 3, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm.

15. The multilayer optical recording medium according to claim 5, wherein the thickness of the first dielectric layer is in a range of 5 nm to 25 nm.