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US 5,540,966 AGranted
Dual layer optical medium having partially reflecting thin film layer
AssigneeMinnesota Mining and Manufacturing Company
InventorMichael B. Hintz
Life of this patent
Estimating the term…
Abstract
A dual layer pre-recorded optical disc includes a transparent substrate, a partially reflective layer, a transparent spacer layer, and a highly reflective layer. One pattern of data pits is provided on the substrate, adjacent the partially reflective layer, and another pattern of data pits is provided on the spacer layer, adjacent the highly reflective layer. The partially reflective layer may be made of silicon carbide. A substrate-incident beam can be used to read data encoded in either data pit pattern depending on which layer the laser is focused upon. The dual layer disc has twice the data storage capacity of conventional single layer discs.
Claims27
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.
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 .mu.m;
- and
- a highly reflective layer provided adjacent the second data pit pattern.
3 more elements
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 .mu.m;
- 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.
7 more elements
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 .mu.m;
- 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.
6 more elements
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 .mu.m;
- and
- a highly reflective layer.
3 more elements
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 .mu.m;
- and
- a highly reflective layer.
2 more elements
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 .mu.m;
- 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.
7 more elements
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 .mu.m;
- 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.
7 more elements
Dependencies are inferred from the claim text.