Optical recording medium and method for manufacturing the same

An optical recording medium comprising:

• a substrate;
• an information signal layer provided on the substrate;
• and
• a protective layer provided on the information signal layer, wherein
• the information signal layer is provided with
• a reflecting layer,
• a recording layer provided on the reflecting layer and
• a first dielectric layer, a second dielectric layer and a third dielectric layer laminated successively on the recording layer,
• refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are different from each other between the adjacent dielectric layers to each other,
• among the first dielectric layer, the second dielectric layer and the third dielectric layer, the dielectric layer having the highest refractive index contains, as a main component, at least one member selected from the group consisting of titanium oxide, niobium oxide and a mixture of zinc sulfide and silicon oxide, and
• the dielectric layer having the highest refractive index has a refractive index of 2.3 or more at a wavelength of 405 nm, and
• when refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are defined as n1, n2 and n3, respectively, the refractive indexes n1, n2 and n3 are satisfied with a relationship of n2>n1 and n2>n3.

A method for manufacturing an optical recording medium comprising:

• forming an information signal layer on a substrate;
• and
• forming a protective layer on the information signal layer, wherein
• the formation of an information signal layer includes successive lamination of a recording layer, a first dielectric layer, a second dielectric layer and a third dielectric layer on a substrate,
• refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are different from each other between the adjacent dielectric layers to each other,
• among the first dielectric layer, the second dielectric layer and the third dielectric layer, the dielectric layer having the highest refractive index contains, as a main component, at least one member selected from the group consisting of titanium oxide, niobium oxide and a mixture of zinc sulfide and silicon oxide, and
• the dielectric layer having the highest refractive index has a refractive index of 2.3 or more at a wavelength of 405 nm, and
• when refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are defined as n1, n2 and n3, respectively, the refractive indexes n1, n2 and n1 are satisfied with a relationship of n1>n2>n3.

An optical recording medium comprising:

• a substrate;
• an information signal layer provided on the substrate;
• and
• a protective layer provided on the information signal layer, wherein
• the information signal layer is provided with:
• a reflecting layer,
• a recording layer provided on the reflecting layer and
• a first dielectric layer, a second dielectric layer and a third dielectric layer laminated successively on the recording layer,
• refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are different from each other between the adjacent dielectric layers to each other, and
• among the first dielectric layer, the second dielectric layer and the third dielectric layer, the dielectric layer having the highest refractive index has a refractive index of 2.3 or more at a wavelength of 405 nm, and
• when refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are defined as n1, n2 and n3, respectively, the refractive indexes n1, n2 and n3 are satisfied with a relationship of n1>n2>n3.

A method for manufacturing an optical recording medium comprising:

• forming an information signal layer on a substrate;
• and
• forming a protective layer on the information signal layer, wherein
• the formation of an information signal layer includes successive lamination of a recording layer, a first dielectric layer, a second dielectric layer and a third dielectric layer on a substrate,
• refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are different from each other between the adjacent dielectric layers to each other,
• among the first dielectric layer, the second dielectric layer and the third dielectric layer, the dielectric layer having the highest refractive index contains, as a main component, at least one member selected from the group consisting of titanium oxide, niobium oxide and a mixture of zinc sulfide and silicon oxide, and
• the dielectric layer having the highest refractive index has a refractive index of 2.3 or more at a wavelength of 405 nm, and
• when refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are defined as n1, n2 and n3, respectively, the refractive indexes n1, n2 and n3 are satisfied with a relationship of n2>n1 and n2>n3.

An optical recording medium comprising:

• a substrate;
• an information signal layer provided on the substrate;
• and
• a protective layer provided on the information signal layer, wherein
• the information signal layer is provided with:
• a reflecting layer,
• a recording layer provided on the reflecting layer and
• a first dielectric layer, a second dielectric layer and a third dielectric layer laminated successively on the recording layer,
• refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are different from each other between the adjacent dielectric layers to each other, and
• among the first dielectric layer, the second dielectric layer and the third dielectric layer, the dielectric layer having the highest refractive index has a refractive index of 2.3 or more at a wavelength of 405 nm, and
• when refractive indexes of the first dielectric layer, the second dielectric layer and the third dielectric layer are defined as n1, n2 and n3, respectively, the refractive indexes n1, n2 and n3 are satisfied with a relationship of n2>n1 and n2>n3.