GB2060973A - Optical video disc for recording and readout - Google Patents

Optical video disc for recording and readout Download PDF

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Publication number
GB2060973A
GB2060973A GB8014177A GB8014177A GB2060973A GB 2060973 A GB2060973 A GB 2060973A GB 8014177 A GB8014177 A GB 8014177A GB 8014177 A GB8014177 A GB 8014177A GB 2060973 A GB2060973 A GB 2060973A
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Prior art keywords
layer
recording
light
readout
nanometers
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GB8014177A
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RCA Corp
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RCA Corp
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Publication of GB2060973A publication Critical patent/GB2060973A/en
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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
    • G11B2007/24302—Metals or metalloids
    • G11B2007/24306—Metals or metalloids transition metal elements of groups 3-10
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
    • G11B2007/24302—Metals or metalloids
    • G11B2007/24314—Metals or metalloids group 15 elements (e.g. Sb, Bi)
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
    • G11B2007/24302—Metals or metalloids
    • G11B2007/24316—Metals or metalloids group 16 elements (i.e. chalcogenides, Se, Te)
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
    • G11B2007/25705—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials
    • G11B2007/2571—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials containing group 14 elements except carbon (Si, Ge, Sn, Pb)
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
    • G11B2007/25705—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials
    • G11B2007/25715—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials containing oxygen
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/253—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates
    • G11B7/2531—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising glass
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/253—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates
    • G11B7/2533—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising resins
    • G11B7/2534—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising resins polycarbonates [PC]
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/258—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective layers
    • G11B7/2585—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective layers based on aluminium

Landscapes

  • Optical Record Carriers And Manufacture Thereof (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

An optical recording medium 30 for use in an optical recording and readout system wherein the recording and readout wavelengths differ by more than 100 nanometers. High sensitivity on recording and high contrast between recorded 22 and unrecorded 24 portions of the recording medium on readout are achieved by so choosing the optical constants of the reflective 16, transmissive 18 and absorptive 20 layers and the thicknesses of the transmissive and absorptive layers that the sum of the respective reflectivities of the medium at the recording and read out wavelengths is less than 0.3. <IMAGE>

Description

SPECIFICATION Optical video disc for recording and readout This invention aims to provide an optical recording medium in which information can be recorded at one wavelength and read out at a second wavelength and which has reduced reflectivity, the ratio of reflected to incident light intensity, at each of these wavelengths.
Spong, U.S. Patent No.4,097,895 issued June 1978, has disclosed an ablative optical recording medium, for use in an optical recording system, which comprises a light reflective layer which is coated with a thin film of a light absorptive organic material, A focused, modulated light beam, such as a light beam from an argon ion laser, when directed at the recording medium, vaporizes or ablates the light absorptive layer, leaving an opening in this layer and exposing the light reflecting layer. The thickness of the light absorptive layer is chosen so that the reflectivity of the recording medium is reduced.
Bell, in a co-pending application entitled "Information Record", Serial No. 054,437, filed July 3, 1979, which is a continuation of Serial No.782,032, filed March 1977, now abandoned, has disclosed an ablative optical recording medium for use in an optical recording system. The optical recording medium comprises a light reflective layer, a layer of a light transmissive material overlying the light reflective layer and a layer of a light absorptive material overlying the light transmissive layer.The thickness of the light absorptive layer is so related to the thickness of the lighttransmissive layer and the optical constants of the light reflective, transmissive and absorptive layers, so as to reduce the optical reflectivity of the recording medium such that a maximum fraction of light impinging on the recording medium from a focused, modulated light beam of a predetermined wavelength is absorbed and converted to thermal energy in the light absorbing layer.
The thermal energy ablates or melts the light absorptive layer producing an opening in the light absorptive layer thus exposing the underlying light reflecting layer through the light transmissive layer.
The reflectivity in the area of the opening in the light absorptive layer is essentially that of the light reflective layer and is much greater than that of the surrounding unexposed region. During readout this difference in reflectivities is detected optically and converted into an electrical signal representative of the recorded information.
The recording process typically requires a high powered laser, such as an argon ion laser, because of the low sensitivity of the recording medium. For readout however, only a low powered laser, such as a helium-neon or a semiconductor injection laser, is required. In recording and readout systems which require additional read only stations or in read only systems it would be preferable to use such low power lasers for readout. The reflectivity of the recording medium, however, is minimized at the recording wavelength in order to maximize the sensitivity during the recording process. This will lead, in general, to a reduction in the reflectivity difference between exposed and unexposed areas of the recording medium when the readout wavelength differs significantly from the recording wavelength.This reduced reflectivity difference leads to a decrease in the signal-to-noise ratio obtainable upon readout, thus degrading the overall system performance. Thus, for maximum performance, the recording and read out wavelengths should be about the same.
It would be desirable to have a recording medium whose reflectivity is simultaneously low at both recording and read out wavelengths, which wavelengths differ significantly from one another, thus providing high sensitivity upon recording and a high signal-to-noise ratio on readout.
According to the invention: An improved optical recording medium comprising a light reflective layer, a light transmissive layer overlying the light reflective layer and a light absorptive layer overlying the light transmissive layer wherein the optical constants of the light reflective layer, the light transmissive layer and the light absorptive layer, and the thicknesses of the transmissive and absorptive layers are such that the sum of the reflectivities of the recording medium at the recording and readout wavelengths, which differ in wavelength by at least 100 nanometers, is less than about 0.3.
In the drawings: Figure 1 is a schematic illustration of a cross-sectional view of a recording medium of the invention.
Figure 2 is a schematic illustration of a cross-sectional view of a recording medium of the invention with information recorded therein.
Figure 1 shows an illustrative embodiment of a recording medium 10 of the invention which comprises a substrate 12 having a surface 14; a light reflective layer 16, overlying the surface 14 of the substrate 12, which reflects light at the wavelengths of the recording and readout light beams; a light transmissive layer 18, overlying the light reflective layer 16, which is substantially transparent at the recording and readout wavelengths; and a light absorptive layer 20, overlying the light transmissive layer 18, which is absorbing of light at the wavelengths of the recording and readout light beams.
The substrate 12 may be formed of a glass or plastic material, such as polyvinyl chloride, typically in the form of a disk. Alternatively, substrate 12 may also be formed of a material, such as aluminum, which reflects light at both the recording and readout wavelengths thus combining the functions of the substrate 12 and the light reflecting layer 16. A substrate, if present, need only be thick enough to support the remainder of the structure.
Roughness of the surface 14 on the scale of the focused light beam diameter will produce noise in the signal channel during readout. A non-conformal coating of a plastic material, such as an epoxy resin, on the surface 14 prior to formation of the light reflective layer 16 thereon will produce a microscopically smooth surface, eliminating this noise source.
The light reflective layer 16 reflects a substantial fraction of the incident light at both the recording and readoutwavelengths and is typically formed of a metal, such as aluminum or gold, which exhibits high reflectivity at both wavelengths. This layer, which is typically about 30 to 60 nanometers thick, may be deposited on the surface 14 of the substrate 12 using vacuum evaporation techniques.
The lighttransmissive layer 18 is formed of a material which is substantiallytransparent at both the recording and readout wavelengths. A typical material useful for this layer is silicon dioxide which may be deposited on the light reflective layer 16 using electron beam evaporation techniques.
The light absorptive layer 20 is formed of a material which absorbs light at both the recording and readout wavelengths. Suitable materials include titanium, rhodium, bismuth, tellurium, and tellurium based alloys deposited by an appropriate technique such as vacuum evaporation. After exposure to the atmosphere, some of these materials will oxidize leaving an absorbing layer which is thinner than the layer originally deposited. This effect may be compensated for by depositing a layer which is thicker than that desired with the subsequent oxidation reducing its effective thickness to the desired value. The thicknesses of the absorptive layer discussed or claimed below are the desired values.
To eliminate or reduce signal defects caused by surface dust which precipitates from the environment, an overcoat layer from about 0.05 to about 1 millimeter thick is applied to the light absorptive layer. Dust particles which settle on the upper surface of the overcoat layer are far removed from the focal plane of the optical system so that their effect on the recording or readout of information on the disk is considerably reduced. A useful material for this application is a silicone resin.
The thicknesses of the transmissive layer 18 and the absorptive layer 20 are interrelated and are adjusted such that the reflectivities of the recording medium at both the recording and readout wavelengths are simultaneously reduced. Preferably the sum of the reflectivities of the recording medium at the record and readout wavelengths is less than 0.3.
The optimal values of the thicknesses of the transmissive and absorptive layers can be calculated using, for example, the matrix method as discussed in "Opticai Properties of Thin Solid Films" by O.S. Heavens, Dover Publications, Inc., New York, 1965, p. 69. This or other approaches use the complex optical constants of the light reflective layer, the light transmissive layer and the light absorptive layer; the recording and readout wavelengths; and a fixed thickness of either the light transmissive or the light absorptive layer to determine the thickness of the remaining layer which will produce a minimum in the reflectivity at the record and readout wavelengths.
Alternatively, useful values of thickness of the lighttransmissive and absorptive layers can be obtained by depositing the light transmissive layer as described above and then depositing the light absorptive layer while monitoring the reflectivity of the recording medium at both the recording and readout wavelengths.
The deposition process for the light absorptive layer is then stopped at a point where the sum of the reflectivities at the two wavelengths is less than 0.3.
The light transmissive layer is at least 10 nanometers thick and is typically from about 20 nanometers to about 150 nanometers thick. Typical values for the thickness of the absorptive layer are from about 2 nanometers to about 30 nanometers. Some thicknesses of the transmissive and absorptive layers of a recording medium which has a reduced reflectivity at a recording wavelength of 488 nanometers and a readout wavelength of 800 nanometers and are suitable for use in a system for optical recording and readout are listed in Tables I and II. In Table I the light absorptive layer is titanium and in Table II the light absorptive layer is tellurium. In the Tables, R488 and R800 are the calculated reflectivities of the recording medium at 488 and 800 nanometers respectively and S is the sum of the reflectivities R488 + R800. In each case the light transmissive layer is silicon dioxide.
TABLE I Thickness R488 R800 S Ti SiO2 R488 + R800 7 nm 50 nm 0.000 0.11 0.11 7 nm 80 nm 0.16 0.000 0.16 8 nm 55 nm 0.02 0.05 0.07 TABLE II Thickness R488 R800 S Te SiO2 R488 + R800 3.5 nm 75 nm 0.000 0.05. 0.05 6 nm 52.5 nm 0.14 0.000 0.14 4 nm 72.5 nm 0.01 0.03 0.04 Table Ill summarizes data of the reflectivities at 488 nanometers and 800 nanometers and the sum of these reflectivities for a recording medium having a light transmissive layer of silicon dioxide and a light absorptive layer of titanium. In each case the reflectivity at the lower wavelength is less than 0.3 while the reflectivity at the higher wavelength and the sum of the reflectivities are both greater than 0.3.
TABLE Ill Thickness R488 R800 S Ti SiO2 R488 + R800 3 nm 25 nm 0.19 0.41 0.60 6 nm 25 nm 0.25 0.47 0.72 7 nm 30 nm 0.11 0.34 0.45 9 nm 25 no 0.11 0.31 0.42 Figure 2 is an illustrative embodiment of a recording medium 30 of the invention with information recorded therein. The Figure shows a cross-sectional view of an information track which has been recorded in the form of a series of openings 22 in the light absorptive layer 20 thus forming an information record.
Typically the information is coded on the disk by varying the length of the openings 22 and of the unexposed areas 24 of the light absorptive layer 20 between the openings 22 along the direction of the track. The length of the openings 22 are determined by the length of time the disk is exposed to the recording light beam and the speed at which the disk is moving through the focal plane of the recording light beam.
High sensitivity is obtained for recording, typically at 488 nanometers or 514.5 nanometers, because the fraction of the incident light lost by reflection is small. Simultaneously, the contrast in reflectivity between the openings and unexposed areas of the disk is maintained at a high value at the readout wavelength, typically 632.8 or about 800 nanometers, which is desirable for high quality readout of the recorded information.

Claims (16)

1. A recording medium for use in an optical recording and readout system employing recording and readout light beams, which differ in wavelength by at least 100 nanometers, comprising a light reflective layer which reflects light at said recording and readout wavelengths; a light transmissive layer, overlying said reflective layer, of a material which is substantially transparent at said recording and readout wavelengths and which has a thickness greater than about 10 nanometers; and a light absorptive layer, overlying said transmissive layer, of a material which is absorptive of light at said recording and readout wavelengths; wherein the optical constants of said reflective, transmissive, and absorptive layers and the thicknesses of said transmissive and absorptive layers are such that the sum of the reflectivities of said recording medium at said recording and readout wavelengths is less than about 0.3.
2. A recording medium according to Claim 1 wherein said reflective layer is supported on a substrate.
3. A recording medium according to Claim 1 wherein said reflective layer is aluminum.
4. A recording medium according to Claim 1 wherein said transmissive layer is silicon dioxide.
5. A recording medium according to Claim 4 wherein the thickness of said transmissive layer is from about 20 nanometers to about 150 nanometers.
6. A recording medium according to Claim 1 wherein said absorptive layer is composed of a material selected from the group consisting of titanium, rhodium, bismuth, tellurium, and tellurium based alloys.
7. A recording medium according to Claim 6 wherein the thickness of said absorptive layer is from about 2 nanometers to about 30 nanometers.
8. An information record for use in an optical recording and readout system employing recording and readout light beams, which differ in wavelength by at least 100 nanometers, comprising: a light reflective layer which reflects light at said recording and readout wavelengths; a light transmissive layer, overlying said reflective layer, of a material substantially transparent to light at said recording and readout wavelengths and having a thickness greater than 10 nanometers; and a light absorptive layer, overlying said transmissive layer, of a material which is absorptive of light at said recording and readout wavelengths with an information track formed therein; wherein the optical constants of said reflective, transmissive, and absorptive layers and the thicknesses of said transmissive and absorptive layers are such that the sum of the reflectivities of said recording medium at said recording and readout wavelengths is less than 0.3; wherein said information track comprises a sequence of openings in said absorptive layer with variations in either or both the length of the openings along the track and the spacing between successive openings being representative of recorded information.
9. An information record according to Claim 8 wherein said reflective layer is supported by a substrate.
10. An information record according to Claim 8 wherein said reflective layer is aluminum.
11. An information record according to Claim 8 wherein said transmissive layer is silicon dioxide.
12. An information record according to Claim 11 wherein the thickness of said transmissive layer is from about 20 nanometers to about 150 nanometers.
13. An information record according to Claim 8 wherein said absorptive layer is composed of a material selected from a group consisting of titanium, rhodium, bismuth, tellurium and tellurium based alloys.
14. An information record according to Claim 13 wherein the thickness of said absorptive layer is from about 2 nanometers to about 30 nanometers.
15. A recording medium substantially as herein before described and shown with particular reference to Figure 1 of the accompanying drawing.
16. An information record substantially as hereinbefore described and shown with particular reference to Figure 2 of the accompanying drawing.
GB8014177A 1979-10-09 1980-04-30 Optical video disc for recording and readout Pending GB2060973A (en)

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US8273479A 1979-10-09 1979-10-09

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JP (1) JPS5660988A (en)
DE (1) DE3021103A1 (en)
FR (1) FR2467460A1 (en)
GB (1) GB2060973A (en)
IT (1) IT1130751B (en)
NL (1) NL8003329A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113380278A (en) * 2018-11-20 2021-09-10 中国科学院上海高等研究院 Optical disk reading method, reading device and optical disk reading and writing device based on nano photoetching

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4285056A (en) * 1979-10-17 1981-08-18 Rca Corporation Replicable optical recording medium
NL8202229A (en) * 1982-06-02 1984-01-02 Docdata Bv MEDIUM FOR RECORDING OPTICALLY READABLE INFORMATION.

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113380278A (en) * 2018-11-20 2021-09-10 中国科学院上海高等研究院 Optical disk reading method, reading device and optical disk reading and writing device based on nano photoetching

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IT8022305A0 (en) 1980-05-23
JPS5660988A (en) 1981-05-26
FR2467460A1 (en) 1981-04-17
NL8003329A (en) 1981-04-13
DE3021103A1 (en) 1981-04-23
IT1130751B (en) 1986-06-18

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