Dual layer optical medium having partially reflecting thin film layer

Claim 2

An optical storage medium, comprising, in order: a transparent substrate having a pattern of pits in one major surface thereof; a partially reflective layer adjacent the pit pattern, having an index of refraction having a real component, n, wherein 2.6<n<3.2, and an imaginary component, K, less than 0.4, measured at any wavelength within the range 500 to 850 nm; a transparent polymer spacer layer having a thickness within the range of a highly reflective layer.

Claim 3

The medium of claim 1, wherein the transparent substrate comprises polycarbonate and the spacer layer comprises a photopolymer, and the spacer layer has a second pattern of pits in one major surface thereof, said second pattern of pits being adjacent the highly reflective layer.

Claim 4

The medium of claim 1, wherein the partially reflective layer has an internal surface reflectivity which varies by less than ±0.03 over thickness variations in the partially reflective layer of ±10%.

Claim 5

The medium of claim 1, wherein the partially reflective layer comprises silicon carbide.

Claim 6

The medium of claim 4, wherein the silicon carbide from about 5 to 15 atomic % oxygen.

Claim 7

The medium of claim 5, wherein the silicon carbide is amorphous.

Claim 8

A dual layer pre-recorded optical disc, comprising, in order: a transparent substrate having a first data pit pattern in one major surface thereof; a partially reflective layer, adjacent the first data pit pattern, comprising silicon carbide; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer opposite the partially reflective layer; the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern.

Claim 9

A dual layer pre-recorded optical disc, comprising, in order: a transparent substrate having a first data pit pattern in one major surface thereof; a partially reflective layer, adjacent the first data pit pattern, comprising silicon carbide; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer opposite the partially reflective layer; the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern.

Claim 10

The medium of claim 7, wherein the partially reflective layer is from 30 to 80 nm thick.

Claim 11

The medium of claim 7, wherein the partially reflective layer comprises silicon carbide containing from about 5 to 15 atomic % oxygen.

Claim 12

The medium of claim 7, wherein the ratio of silicon to carbon in the partially reflecting layer is about 1:1.3.

Claim 13

The medium of claim 7, wherein the silicon carbide is amorphous.

Claim 14

The medium of claim 7, wherein the partially reflective layer has an internal surface reflectivity which varies by less than ±0.03 over thickness variations in the partially reflective layer of ±10%.

Claim 15

An optical storage system, comprising: an optical storage medium, comprising, in order: a transparent substrate having a pattern of pits in one major surface thereof; a partially reflective layer comprising silicon carbide; a transparent polymer spacer layer having a thickness within the range of from about 5 to 100 μm; and a highly reflective layer; a focused laser beam positioned to enter the medium through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer; and a photodetector positioned to detect the reflected laser beam exiting the medium.

Claim 16

An optical storage system, comprising: an optical storage medium, comprising, in order: a transparent substrate having a pattern of pits in one major surface thereof; a partially reflective layer comprising silicon carbide; a transparent polymer spacer layer having a thickness within the range of from about 5 to 100 μm; and a highly reflective layer; a focused laser beam positioned to enter the medium through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer; and a photodetector positioned to detect the reflected laser beam exiting the medium.

Claim 17

A pre-recorded dual layer optical disc storage system, comprising; A dual layer pre-recorded optical disc, comprising, in order: a transparent substrate having a first data pit pattern in one major surface thereof, a partially reflective layer, adjacent the first data pit pattern, having an index of refraction having a real component, n, wherein 2.6>n>3.2, and an imaginary component,K, less than 0.4, measured at any wavelength within the range of from 500 to 850 nm; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern, a focused laser beam positioned to enter the disc through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer, and a photodetector positioned to detect the reflected laser beam exiting the disc.

Claim 18

A pre-recorded dual layer optical disc storage system, comprising; A dual layer pre-recorded optical disc, comprising, in order: a transparent substrate having a first data pit pattern in one major surface thereof, a partially reflective layer, adjacent the first data pit pattern, having an index of refraction having a real component, n, wherein 2.6>n>3.2, and an imaginary component,K, less than 0.4, measured at any wavelength within the range of from 500 to 850 nm; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern, a focused laser beam positioned to enter the disc through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer, and a photodetector positioned to detect the reflected laser beam exiting the disc.

Claim 19

An optical storage system, comprising: in order: a transparent substrate having a pattern of pits in one major surface thereof; a partially reflective layer adjacent the pit pattern, having an index of refraction having a real component, n, wherein 2.6<n<3.2, and an imaginary component, K, less than 0.4, measured over a range of wavelengths from 500 to 850 nm; a transparent polymer spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer.

Claim 20

An optical storage system, comprising: in order: a transparent substrate having a pattern of pits in one major surface thereof; a partially reflective layer adjacent the pit pattern, having an index of refraction having a real component, n, wherein 2.6<n<3.2, and an imaginary component, K, less than 0.4, measured over a range of wavelengths from 500 to 850 nm; a transparent polymer spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer.

Claim 21

The medium of claim 15, wherein the transparent substrate comprises polycarbonate and the spacer layer comprises a photopolymer, and the spacer layer has a second pattern of pits in one major surface thereof, said second pattern of pits being adjacent the highly reflective layer.

Claim 22

The medium of claim 15, wherein the partially reflective layer has an internal surface reflectivity which varies by less than ±0.03 over thickness variations in the partially reflective layer of ±10%.

Claim 23

An optical storage medium, comprising, in order: a transparent substrate having a pattern of pits in one major surface thereof; a partially reflective layer adjacent the pit pattern, having an index of refraction having a real component, n, wherein 2.6<n<3.2, and an imaginary component, K, wherein K<0.4, measured over wavelengths from 650 nm; a transparent polymer spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer.

Claim 24

An optical storage medium, comprising, in order: a transparent substrate having a pattern of pits in one major surface thereof; a partially reflective layer adjacent the pit pattern, having an index of refraction having a real component, n, wherein 2.6<n<3.2, and an imaginary component, K, wherein K<0.4, measured over wavelengths from 650 nm; a transparent polymer spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer.

Claim 25

The medium of claim 18, wherein 2.7<n<3.1.

Claim 26

The medium of claim 19, wherein K<0.2.

Claim 27

The medium of claim 19, wherein 0.1<K<0.2.

Claim 28

The medium of claim 18, wherein the transparent substrate comprises polycarbonate and the spacer layer comprises a photopolymer, and the spacer layer has a second pattern of pits in one major surface thereof, said second pattern of pits being adjacent the highly reflective layer.

Claim 29

The medium of claim 18, wherein the partially reflective layer has an internal surface reflectivity which varies by less than ±0.03 over thickness variations in the partially reflective layer of ±10%.

Claim 30

A pre-recorded dual layer optical disc storage system, comprising: a dual layer pre-recorded optical disc, comprising in order: a transparent substrate having a first data pit pattern in one major surface thereof; a partially reflective layer, adjacent the first data pit pattern, having an index of refraction having a real component, n, wherein 2.6<n<3.2, and an imaginary component, K, less than 0.4, measured at any wavelength from 500 to 850 nm; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer opposite the partially reflective layer, the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern; a focused laser beam positioned to enter the disc through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer; and a photodetector positioned to detect the reflected laser beam exiting the disc.

Claim 31

A pre-recorded dual layer optical disc storage system, comprising: a dual layer pre-recorded optical disc, comprising in order: a transparent substrate having a first data pit pattern in one major surface thereof; a partially reflective layer, adjacent the first data pit pattern, having an index of refraction having a real component, n, wherein 2.6<n<3.2, and an imaginary component, K, less than 0.4, measured at any wavelength from 500 to 850 nm; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer opposite the partially reflective layer, the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern; a focused laser beam positioned to enter the disc through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer; and a photodetector positioned to detect the reflected laser beam exiting the disc.

Claim 32

A pre-recorded dual layer optical disc storage system, comprising: a dual layer pre-recorded optical disc, comprising, in order: a transparent substrate having a first data pit pattern in one major surface thereof; a partially reflective layer, adjacent the first data pit pattern, having an index of refraction having a real component, n, wherein 2.7<n<3.1, and an imaginary component, K, wherein K<0.4, measured at 650 nm; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer opposite the partially reflective layer, the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern; a focused laser beam positioned to enter the disc through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer; and a photodetector positioned to detect the reflected laser beam exiting the disc.

Claim 33

A pre-recorded dual layer optical disc storage system, comprising: a dual layer pre-recorded optical disc, comprising, in order: a transparent substrate having a first data pit pattern in one major surface thereof; a partially reflective layer, adjacent the first data pit pattern, having an index of refraction having a real component, n, wherein 2.7<n<3.1, and an imaginary component, K, wherein K<0.4, measured at 650 nm; a transparent spacer layer having a second data pit pattern in one major surface thereof, said major surface being on a side of the spacer layer opposite the partially reflective layer, the spacer layer having a thickness within the range from about 5 to 100 μm; and a highly reflective layer provided adjacent the second data pit pattern; a focused laser beam positioned to enter the disc through the substrate; means for adjusting focal position of the laser beam, whereby the beam may be focused on either the partially reflective layer or the highly reflective layer; and a photodetector positioned to detect the reflected laser beam exiting the disc.

Claim 34

The system of claim 25, wherein K<0.2.

Claim 35

The system of claim 25, wherein 0.1<K<0.2.