FR2467460A1 - OPTICAL VIDEODISK FOR RECORDING AND READING AT TWO DIFFERENT WAVE LENGTHS - Google Patents

OPTICAL VIDEODISK FOR RECORDING AND READING AT TWO DIFFERENT WAVE LENGTHS Download PDF

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Publication number
FR2467460A1
FR2467460A1 FR8012663A FR8012663A FR2467460A1 FR 2467460 A1 FR2467460 A1 FR 2467460A1 FR 8012663 A FR8012663 A FR 8012663A FR 8012663 A FR8012663 A FR 8012663A FR 2467460 A1 FR2467460 A1 FR 2467460A1
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France
Prior art keywords
light
recording
layer
wavelengths
reading
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FR8012663A
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French (fr)
Inventor
Robert Alfred Bartolini
Alan Edward Bell
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RCA Corp
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RCA Corp
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Publication of FR2467460A1 publication Critical patent/FR2467460A1/en
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    • 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

L'invention concerne un support d'enregistrement à utiliser dans un système optique d'enregistrement et de lecture employant des faisceaux lumineux d'enregistrement et de lecture, dont les longueurs d'onde diffèrent d'au moins 100 nanomètres, et il comprend une couche réfléchissant la lumière aux longueurs d'onde d'enregistrement et de lecture, une couche transmettant la lumière la recouvrant, en un matériau qui est sensiblement transparent aux longueurs d'onde d'enregistrement et de lecture et dont l'épaisseur est supérieure à environ 10 nanomètres, et une couche absorbant la lumière recouvrant la couche transmettant la lumière, en un matériau absorbant la lumière aux longueurs d'onde d'enregistrement et de lecture. Selon l'invention, les constantes optiques des couches 16 réfléchissant la lumière, 18 la transmettant et 20 l'absorbant et les épaisseurs des couches 18 transmettant la lumière et 20 l'absorbant sont telles que la somme des réflectivités du support d'enregistrement aux longueurs d'onde d'enregistrement et de lecture soit inférieure à environ 0,3. L'invention s'applique notamment aux vidéodisques. (CF DESSIN DANS BOPI)Provided is a recording medium for use in an optical recording and playback system employing recording and playback light beams, whose wavelengths differ by at least 100 nanometers, and includes a a layer reflecting light at the recording and reading wavelengths, a light transmitting layer covering it, of a material which is substantially transparent at the recording and reading wavelengths and having a thickness greater than about 10 nanometers, and a light absorbing layer overlying the light transmitting layer, made of a light absorbing material at the recording and reading wavelengths. According to the invention, the optical constants of the light reflecting, 18 transmitting and 20 absorbent layers 16 and the thicknesses of the light transmitting and 20 absorbent layers 18 are such that the sum of the reflectivities of the recording medium to recording and playback wavelengths is less than about 0.3. The invention applies in particular to video discs. (CF DRAWING IN BOPI)

Description

I La présente invention se rapporte à un support d'enregistrement optiqueThe present invention relates to an optical recording medium

o l'information peut être enregistrée à une longueur d'onde et lue à une seconde longueur d'onde, et qui a une réflectivité réduite, c'est-à-dire le rapport de l'intensité de lumière  o the information can be recorded at a wavelength and read at a second wavelength, and which has a reduced reflectivity, i.e. the ratio of light intensity

réfléchie à incidente, à chacune de ces longueurs d'onde.  reflected at incident, at each of these wavelengths.

Spong, dans le brevet US nO 4 097 895 du 27 Juin 1978 a révélé un support d'enregistrement optique par ablation, à utiliser dans un système d'enregistrement optique, qui comprend une couche réfléchissant la lumière enduite d'une pellicule mince d'un matériau organique absorbant la lumière. Un faisceau lumineux focalisé et modulé, tel qu'un faisceau de lumière provenant d'un laser à l'ion argon, quand il est dirigé sur le support d'enregistrement, vaporise ou produit l'ablation de la couche absorbant la lumière, laissant une ouverture dans cette couche et exposant la couche réfléchissant la lumière. L'épaisseur de la couche absorbant la lumière est choisie de façon que la réflectivité du support  Spong, U.S. Patent No. 4,097,895, June 27, 1978, disclosed an ablative optical recording medium for use in an optical recording system, which comprises a light reflective layer coated with a thin film of light. an organic material absorbing light. A focused and modulated light beam, such as a beam of light from an argon ion laser, when it is directed at the recording medium, vaporizes or produces the ablation of the light absorbing layer, leaving an opening in this layer and exposing the light reflective layer. The thickness of the light absorbing layer is chosen so that the reflectivity of the support

d'enregistrement soit réduite.registration is reduced.

Bell, dans une demande de brevet US en cours intitulée "Information Record", n0 054 437, déposée le 3 Juillet 1979, a révélé un support d'enregistrement optique par ablation à utiliser dans un système d'enregistrement optique. Le support d'enregistrement optique se compose d'une couche réfléchissant la lumière, d'une couche d'un matériau transmettant la lumière recouvrant la couche réfléchissant i lumière et d'une couche d'un  Bell, in an on-going US patent application entitled "Information Record", No. 054,437, filed July 3, 1979, disclosed an ablation optical recording medium for use in an optical recording system. The optical recording medium is composed of a light reflecting layer, a layer of a light transmitting material covering the light reflecting layer and a layer of a light reflecting layer.

matériau absorbant la lumière recouvrant la couche trans-  light-absorbing material covering the trans-layer

mettant la lumière. L'épaisseur de la couche absorbant la lumière est en rapport à l'épaisseur de la couche transmettant la lumière et aux constantes optiques des couches réfléchissant, transmettant et absorbant la lumière de façon à réduire la réflectivité optique du support d'enregistrement afin qu'une fraction maximum  putting the light. The thickness of the light absorbing layer is related to the thickness of the light transmissive layer and the optical constants of the light reflecting, transmitting and absorbing layers so as to reduce the optical reflectivity of the recording medium so that a maximum fraction

de la lumière faisant impact sur le support d'enregistre-  light impacting the recording medium

ment et provenant d'un faisceau de lumière modulé et focalisé d'une longueur d'onde prédéterminée, soit absorbée et convertie en énergie thermique dans la couche absorbant  and from a modulated and focused light beam of a predetermined wavelength is absorbed and converted into thermal energy in the absorbing layer

la lumière.the light.

L'énergie thermique effectue l'ablation ou fait fondre la couche absorbant la lumière,produisant une ouverture dans cette couche, et exposant ainsi la couche sous-jacente réfléchissant la lumière à travers la couche transmettant  The thermal energy ablates or melts the light absorbing layer, producing an aperture therein, thereby exposing the underlying light reflective layer through the transmitting layer.

la lumière.the light.

La réflectivité dans la zone de l'ouverture de la couche absorbant la lumière est essentiellement celle de la couche réfléchissant la lumière et est bien supérieure à celle de la région non exposée environnante. Pendant la lecture, cette différence de réflectivité est détectée optiquement et convertie en un signal électrique  The reflectivity in the area of the aperture of the light absorbing layer is substantially that of the light reflective layer and is much greater than that of the surrounding unexposed region. During reading, this difference in reflectivity is optically detected and converted into an electrical signal

représentatif de l'information enregistrée.  representative of the recorded information.

Le procédé d'enregistrement nécessite typiquement un laser de forte puissance, comme un laser à l'ion  The recording process typically requires a high power laser, such as an ion laser

argon du fait de la faible sensibilité du support.  argon because of the low sensitivity of the support.

d'enregistrement. Cependant, pour la lecture, il ne faut qu'un laser de faible puissance comme un laser hélium-néon ou un laser à injection à semi-conducteur. Dans des système d'enregistrement et de lecture nécessitant des stations supplémentaires de lecture seulement ou dans des systèmes de lecture seulement, il serait préférable d'utiliser de tels lasers de faible puissance pour  recording. However, for reading, only a low power laser such as a helium-neon laser or a semiconductor injection laser is needed. In recording and playback systems requiring additional reading-only stations or in read-only systems, it would be preferable to use such low power lasers for

la lecture. Cependant, la réflectivité du support d'enregis-  reading. However, the reflectivity of the recording medium

trement est diminuéeà3longueur d'onde d'enregistrement afin de rendre maximum la sensibilité pendant je procédé d'enregistrement. Cela peut conduire, en général, à une réduction de la différence de réflectivité entre  This is greatly reduced at the recording wavelength to maximize sensitivity during the recording process. This can lead, in general, to a reduction in the difference in reflectivity between

les zones exposées et non exposéesdu support d'enregistre-  the exposed and unexposed areas of the recording medium

ment quand la longueur d'onde de lecture diffère de  when the reading wavelength differs from

façon importante de la longueur d'onde d'enregistrement.  important way of the recording wavelength.

Cette différence de réflectivité réduite conduit à une diminution du rapport signal/bruit que l'on peut obtenir lors de la lecture, dégradant ainsi la performance générale du système. Ainsi, pour une performance maximale, les longueurs d'onde d'enregistrement et de lecture doivent  This reduced reflectivity difference leads to a decrease in the signal / noise ratio that can be obtained during the reading, thus degrading the overall performance of the system. Thus, for maximum performance, record and read wavelengths must

être à peu près les mêmes.to be pretty much the same.

Il serait souhaitable d'avoir un support d'enregistre-  It would be desirable to have a recording

ment dont la réflectivité soit simultanément faible aux longueurs d'onde d'enregistrement et de lecture, ces longueurs d'onde étant suffisamment différentes l'une de l'autre, pour obtenir ainsi une forte sensibilité lors de l'enregistrement et un fort rapport signal/bruit  whose reflectivity is simultaneously low at the recording and reading wavelengths, these wavelengths being sufficiently different from each other, to thereby obtain a high sensitivity during the recording and a high ratio S / N

à la lecture.reading.

La présente invention se rapporte à un support d'enregistrement optique comprenant une couche réfléchissant la lumière, une couche transmettant la lumière recouvrant la couche réfléchissant la lumière et une couche absorbant la lumière recouvrant la couche transmettant la lumière, o les constantes optiques de la couche réfléchissant la lumière, de la couche transmettant la lumière et de la couche absorbant la lumière et les épaisseurs des couches transmettant et absorbant sont telles que la somme des réflectivités du support d'enregistrement aux longueurs d'onde d'enregistrement et de lecture, qui diffèrent d'au moins 100 nanomètres, soit inférieure  The present invention relates to an optical recording medium comprising a light reflecting layer, a light transmitting layer covering the light reflecting layer and a light absorbing layer covering the light transmitting layer, wherein the optical constants of the layer light-reflecting layer, the light transmissive layer and the light absorbing layer and the thicknesses of the transmitting and absorbing layers are such that the sum of the reflectivities of the recording medium at the recording and reading wavelengths, which differ by at least 100 nanometers, ie less than

à environ 0,3.at about 0.3.

L'invention sera mieux comprise et d'autres buts, caractéristiques, détails et avantages de celle-ci  The invention will be better understood and other purposes, features, details and advantages thereof

apparaîtront plus clairement au cours de la description  will become clearer during the description

explicative qui va suivre faite en référence aux dessins schématiques annexés donnés uniquement à titre d'exemple illustrant un mode de réalisation de l'invention et dans lesquels: - la figure 1 est une illustration schématique  explanatory text which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating an embodiment of the invention and in which: - Figure 1 is a schematic illustration

d'une vue en coupe transversale d'un support d'enregistre-  a cross-sectional view of a recording medium

ment selon 'L'invention; et - la figure 2 est une illustration schématique d'une coupe transversale d'un support d'enregistrement  according to the invention; and - Figure 2 is a schematic illustration of a cross section of a recording medium

selon l'invention, o est enregistrée une information.  according to the invention, o is recorded information.

La figure 1 montre un mode de réalisation d'un support d'enregistrement 10 selon l'invention, qui comprend un substrat l2ayant une surface 14; une couche réfléchissant la lumière 16, recouvrant la surface 14 du substrat 12, qui réfléchit la lumière aux longueurs d'onde des faisceaux lumineux d'enregistrement et de lecture; une couche transmettant la lumière 18, recouvrant la couche 16 réfléchissant la lumière, qui est sensiblement transparente aux longueurs d'onde d'enregistrement et de lecture et une couche absorbant la lumière 20, recouvrant la couche transmettant la lumière 18, qui absorbe la lumière aux longueurs d'onde es faisceaux lumineux d'enregistrement  Fig. 1 shows an embodiment of a recording medium 10 according to the invention, which comprises a substrate 12 having a surface 14; a light reflecting layer 16 covering the surface 14 of the substrate 12, which reflects light at the wavelengths of the recording and reading light beams; a light transmissive layer 18 covering the light reflecting layer 16 which is substantially transparent at the recording and reading wavelengths and a light absorbing layer 20 covering the light transmissive layer 18 which absorbs the light at the wavelengths the recording light beams

et de lecture.and reading.

Le substrat 12 peut être formé en verre ou en matière plastique, comme un chlorurede polyvinyle,typiquement sous forme d'un disque. Alternativement, le substrat 12 peut également être formé en un matériau, tel que de l'aluminium,  The substrate 12 may be formed of glass or plastic, such as a polyvinylchloride, typically in the form of a disc. Alternatively, the substrate 12 may also be formed of a material, such as aluminum,

qui réfléchit la lumière aux longueurs d'onde d'enregistre-  which reflects light at the recording wavelengths

ment et de lecture, combinant ainsi les fonctions du  and reading, thus combining the functions of the

substrat 12 et de la couche 16 réfléchissant la lumière.  substrate 12 and the layer 16 reflecting light.

Un substrat, s'il est présent, doit simplement être suffisamment épais pour supporter le restant de la structure. Une rugosité de la surface 14 à l'échelle du diamètre du faisceau lumineux focalisé produira du bruit dans le canal de signaux pendant la lecture. Un revêtement non conforme en une matière plastique, comme une résine époxy, sur la surface 14 avant formation de la couche 16 réfléchissant la lumière produira une surface microscopiquement lisse ou régulière, éliminant cette  A substrate, if present, should simply be thick enough to support the rest of the structure. A roughness of the surface 14 at the diameter scale of the focused light beam will produce noise in the signal channel during playback. A non-conforming coating of a plastic material, such as an epoxy resin, on the surface 14 prior to forming the light reflecting layer 16 will produce a microscopically smooth or even surface, eliminating this

source de bruit.source of noise.

La couche 16 réfléchissant la lumière réfléchit une fraction sensible de la lumière incidente aux longueurs d'onde d'enregistrement et de lecture, et est typiquement formée en un métal, tel que de l'aluminium ou de l'or, qui présente une forte réflectivité aux deux longueurs d'onde. Cette couche, qui a typiquement de l'ordre de à 60 nanomètres d'épaisseur, peut être déposée sur la surface 14 du substrat 12 en utilisant des techniques  The light reflecting layer 16 reflects a substantial fraction of the incident light at the recording and reading wavelengths, and is typically formed of a metal, such as aluminum or gold, which has a strong reflectivity at both wavelengths. This layer, which is typically of the order of 60 nanometers thick, can be deposited on the surface 14 of the substrate 12 using techniques

d'évaporation sous vide.vacuum evaporation.

La couche 18 transmettant la lumière est formée  The light transmitting layer 18 is formed

en un matériau qui est-sensiblement transparent aux -  in a material that is substantially transparent to

longueurs d'onde d'enregistrement et de lecture. Le dioxyde de silicium est un matériau typique. utile pour cette couche, et il peut être déposé sur la couche 16 en utilisant des techniques d'évaporation par faisceau d'électrons. La couche 20 absorbant la lumière est formée en un matériau qui absorbe la lumière aux longueurs d'onde d'enregistrement et de lecture. On peut citer, comme matériaux appropriés, le titane, lerhodium, le bismuth, le tellurium et des alliages à base de tellurium déposés par une technique appropriée comme une évaporation sous vide. Après exposition à l'atmosphère, certains de ces matériaux s'oxyderont, laissant um couche absorbante plus mince que la couche déposée à l'origine. Cet effet peut être compensé en déposant une couche plus épaisse que celle souhaitée, l'oxydation subséquente réduisant son épaisseur effective à la valeur souhaitée. Les épaisseurs de la couche absorbante décrites sont les  recording and playback wavelengths. Silicon dioxide is a typical material. useful for this layer, and it can be deposited on the layer 16 using electron beam evaporation techniques. The light absorbing layer 20 is formed of a material which absorbs light at recording and reading wavelengths. Suitable materials include titanium, lerodium, bismuth, tellurium and tellurium-based alloys deposited by a suitable technique such as vacuum evaporation. After exposure to the atmosphere, some of these materials will oxidize, leaving an absorbent layer thinner than the originally deposited layer. This effect can be compensated by depositing a thicker layer than desired, the subsequent oxidation reducing its effective thickness to the desired value. The thicknesses of the absorbent layer described are the

valeurs souhaitées.desired values.

Pour éliminer ou réduire des défauts de signal provoqués par une poussière à la surfacequi précipite de l'environnement, une couche de recouvrement de l'ordre de 0,5 à environ 1 mm d'épaisseur est appliquée à la couche absorbant la lumière. Les particules de poussière qui se déposent à la surface supérieure de la couche de recouvrement sont très éloignées du plan focal du système optique, ainsi leur effet sur la lecture et l'enregistrement de l'information sur le disque est considérablement réduit. Comme matériau utile  To eliminate or reduce signal defects caused by surface dust that precipitates from the environment, an overlay layer in the range of 0.5 to about 1 mm thick is applied to the light absorbing layer. The dust particles that are deposited on the upper surface of the cover layer are far away from the focal plane of the optical system, so their effect on the reading and recording of the information on the disc is greatly reduced. As a useful material

dans ce cas, on peut utiliser une résine de silicone.  in this case, a silicone resin can be used.

Les épaisseurs de la couche transmettant la lumière 18 etd2-acouche absorbante 20 sont en'relation et son ajustées de façon que les réflectivités du support d'enregistrement aux longueurs d'onde d'enregistrement et de lecture soient simultanément réduites. De préférence, la somme des réflectivités du support d'enregistrement aux longueurs d'onde d'enregistrement  The thicknesses of the light-transmissive layer 18 and 12-absorbent layer 20 are in correlation and adjusted so that the reflectivities of the recording medium at the recording and reading wavelengths are simultaneously reduced. Preferably, the sum of the reflectivities of the recording medium at recording wavelengths

et de lecture est inférieure à 0,3.  and reading is less than 0.3.

Les valeurs optimales des épaisseurs des couches transmettant la lumière et l'absorbant peuvent être calculées en utilisant, par exemple, la méthode de matrice décrite dans "Optical Properties of Thin Solid Films", par O.S. Heavens, Dover Publications, Inc, New York, 1965, page 69. Cette tentative ou d'autres utilisent les constantes optiques complexes de la couche réfléchissant la lumière, de la couche transmettant la lumière et de la couche absorbant la lumière; les longueurs d'onde d'enregistrement et de lecture; et une épaisseur fixe de la couche transmettant la lumière ou de la couche absorbant la lumière pour déterminer l'épaisseur de la couche restante qui produira un minimum de réflectivité aux longueurs d'onde d'enregistrement  The optimum values of the thicknesses of the light transmissive and absorbent layers can be calculated using, for example, the matrix method described in "Optical Properties of Thin Solid Films", by O.S. Heavens, Dover Publications, Inc., New York, 1965, page 69. This or other attempt utilizes the complex optical constants of the light reflecting layer, the light transmissive layer and the light absorbing layer; recording and reading wavelengths; and a fixed thickness of the light transmissive layer or the light absorbing layer to determine the thickness of the remaining layer which will produce a minimum of reflectivity at the recording wavelengths

et de lecture.and reading.

Alternativement, les valeurs utiles d'épaisseur des couches transmettant et absorbant la lumière peuvent être obtenues en déposant la couche transmettant la lumière comme on l'a décrit ci-dessus puis en déposant la couche absorbant la lumière tout en surveillant la réflectivité du support d'enregistrement aux longueurs d'onde d'enregistrement et de lecture. Le procédé de dépôt de la couche absorbant la lumière est alors arrêté en un point o la somme des réflectivitésaux  Alternatively, the useful thickness values of the light-transmissive and absorbing layers can be obtained by depositing the light-transmissive layer as described above and then depositing the light-absorbing layer while monitoring the reflectivity of the light-absorbing layer. recording at the recording and playback wavelengths. The method of depositing the light absorbing layer is then stopped at a point where the sum of the reflectivities

deux longueurs d'onde est inférieure à 0,3.  two wavelengths is less than 0.3.

La couche transmettant la lumière a au moins 10  The light-transmitting layer has at least 10

nanomètres d'épaisseur et elle a typiquement de l'ordre -  nanometers thick and she typically has order -

de 20 à environ 150 nanomètres d'épaisseur. Les valeurs typiques de l'épaisseur de la couche absorbant la lumière sont comprises entre environ deux nanomètres et environ 30 nanomètres. Certaines épaisseurs des couches transmettant la lumièree l'absorbant d'un support d'enregistrement ayant une réflectivité réduite à une longueur d'onde d'enregistrement de 488 nanomètres et une longueur d'onde de lecture de 800 manomètres et qui sont adaptées pour une utilisation dans un système pour l'enregistrement et la lecture optiques, sont indiquées auitableaux I et II. Au tableau I,la couche absorbant la lumière est en titane et au tableau II,elle est en tellurium. Sur le tableaux,R488 et RS00 sont les réflectivités calculées du support d'enregistrement respectivement à 488 et 800 nanomètres et S est la somme des réflectivités R488 + R800. Dans chaque cas, la couche transmettant la lumière est en dioxyde de silicium.  from 20 to about 150 nanometers thick. Typical values of the thickness of the light absorbing layer are from about two nanometers to about 30 nanometers. Some thicknesses of light-transmissive layers absorbing a recording medium having a reflectivity reduced to a recording wavelength of 488 nanometers and a reading wavelength of 800 nanometers and which are suitable for in a system for optical recording and reading, are shown in Tables I and II. In Table I, the light absorbing layer is made of titanium and in Table II it is in tellurium. In the tables, R488 and RS00 are the calculated reflectivities of the recording medium respectively at 488 and 800 nanometers and S is the sum of the reflectivities R488 + R800. In each case, the light transmissive layer is silicon dioxide.

TABLEAU ITABLE I

Epaisseur R488 R800 S Ti Si02 R488 + R800 7 nm 50 nm! 0,000 0,11 0,11 7.mm 80 nm 0,16 0,000 0,16 8 nm 55 nm 0,02 0,05 0,07  Thickness R488 R800 S Ti Si02 R488 + R800 7 nm 50 nm! 0.000 0.11 0.11 7.mm 80 nm 0.16 0.000 0.16 8 nm 55 nm 0.02 0.05 0.07

TABLEAU IITABLE II

Epaisseur R488 R800 S Te SiO02 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 Le tableau III résume les données des réflectivités à 488 nanomètres et 800 nanomètres et la somme de ces réflectivités pour un support d'enregistrement ayant une couche transmettant la lumière en dioxyde de silicium etuoe couchs. bsortant la lumière en titane. Dans chaque cas, la réflectivité à la longueur d'onde inférieure est inférieure à 0,3 tandis que la réflectivité à la longueur d'onde supérieure et la somme des réflectivités  Thickness R488 R800 S Te SiO02 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 III summarizes the reflectivity data 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 coatings. carrying the titanium light. 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

sont toutes deux supérieures à 0,3.  are both greater than 0.3.

TABLEAU IIITABLE III

Epaisseur R488 R0 S Ti SiO2 R488 + R800 3nm 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 nm 0,11 0,31 0,42 La figure 2 illustre un mode de réalisation d'un support d'enregistrement 30 selon l'invention o est enregistrée une information. La figure 2 montre une vue en coupe transversale d'une piste ou plage d'information qui a été enregistrée sous forme d'une série d'ouvertures 22 dans la couche absorbant la lumière pour former ainsi un support d'enregistrement. Typiquement, l'information est codée sur le disque en faisant varier-la longueur des ouvertures 22 et des zones non exposées 24 de la couche 20 absorbant la lumière entre les ouvertures 22 le long de la direction de lapiste ou plage. Les longueurs des ouvertures 22 sont déterminées par le temps o le disque est exposé au- faisceau: lumineux d'enregistrement et la vitesse à laquelle le disque se déplace à travers le  Thickness R488 R0 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 nm 0.11 0.31 0.42 Figure 2 illustrates an embodiment of a recording medium 30 according to the invention where information is recorded. Fig. 2 shows a cross-sectional view of a track or range of information that has been recorded as a series of apertures 22 in the light absorbing layer to thereby form a recording medium. Typically, the information is encoded on the disk by varying the length of the openings 22 and unexposed areas 24 of the light absorbing layer 20 between the apertures 22 along the lap / lane direction. The lengths of the apertures 22 are determined by the time the disc is exposed to the beam: the recording light and the speed at which the disc moves through the

plan focal du faisceau lumineux d'enregistrement.  focal plane of the recording light beam.

On obtient une forte sensibilité pour l'enregistrement, typiquement à 488 nanomètres ou 514,5 nanomètres, parce que la fraction de lumière incidente perdue par réflexion est faible. Simultanément, le contrastide réflectivité entre les ouvertures et les zones non exposées du disque est maintenu à une valeur élevée à la longueur d'onde de lecture, typiquement 632,8 ou environ 800 nanomètres, ce qui est souhaitable pour une lecture de l'information  High sensitivity for recording is obtained, typically at 488 nanometers or 514.5 nanometers, because the fraction of incident light lost by reflection is small. Simultaneously, the contrastide reflectivity between the openings and unexposed areas of the disk is maintained at a high value at the read wavelength, typically 632.8 or about 800 nanometers, which is desirable for reading the information

enregistrée à une très bonne qualité.  recorded at a very good quality.

Bien entendu, l'invention n'est nullemert limitée au mode de réalisation décrit et représenté qui n'a été donné qu'à titre d'exemple. En particulier, elle comprend tous les moyens constituant des équivalents techniques  Of course, the invention is nullemert limited to the embodiment described and shown which has been given by way of example. In particular, it includes all means constituting technical equivalents

des moyens décrits ainsi que leurs combinaisons si celles-  described means as well as their combinations if these

ci sont exécutées suivant son esprit et mises en oeuvre  These are executed according to his spirit and implemented

dans le cadre de la protection comme revendiquée.  as part of the protection as claimed.

Claims (8)

R E V E N D I C A T I 0 N SR E V E N D I C A T I 0 N S 1. Support d'enregistrement à utiliser dans un système d'enregistrement et de lecture optiques employant des faisceaux lumineux d'enregistrement et de lecture, dont les longueurs d'onde diffèrent d'au moins 100 nanomètres, du type comprenant: une couche réfléchissant la lumière qui réfléchit la lumière aux longueurs d'onde d'enregistrement et de lecture; une couche transmettant la lumière, recouvrant la couche réfléchissant la lumière, en un matériau qui est  A recording medium for use in an optical recording and playback system employing recording and playback light beams, having wavelengths of at least 100 nanometers, of the type comprising: a reflective layer light that reflects light at recording and reading wavelengths; a light transmissive layer covering the light reflecting layer of a material which is sensiblement transparent aux longueurs d'onde d'enregistre-  substantially transparent at recording wavelengths ment et de lecture et dont l'épaisseur est supérieure à environ IC nanometres; et une couche absorbant la lumière, recouvrant la couche transmettant la lumière, en un matériau qui absorbe la lumière aux longueurs d'onde d'enregistrement et de lecture, caractérisé en ce que les constantes optiques desdites couches réfléchissant la lumière (16), transmettant la lumière (18) et absorbant la lumière (20) et les épaisseurs desdites couches transmettant la lumière (18) et absorbant la lumière (20) sont telles que la somme des réflectivités dudit support d'enregistrement aux longueurs d'onde d'enregistrement et de lecture  reading and whose thickness is greater than about IC nanometers; and a light absorbing layer, covering the light-transmissive layer, of a material which absorbs light at the recording and reading wavelengths, characterized in that the optical constants of said light reflecting layers (16), transmitting the light (18) and light absorbing (20) and the thicknesses of said light transmitting (18) and light absorbing (20) layers are such that the sum of the reflectivities of said recording medium at the recording wavelengths and reading soit inférieure à environ 0,3.less than about 0.3. 2. Support d'enregistrement selon la revendication 1, caractérisé en ce que la couche réfléchissant la lumière  Recording medium according to claim 1, characterized in that the light reflective layer (16) est supportée sur un substrat (12).  (16) is supported on a substrate (12). 3. Support selon la revendication 1, caractérisé en ce que la couche réfléchissant la lumière (16) est  3. Support according to claim 1, characterized in that the light reflecting layer (16) is en aluminium.in aluminium. 4. Support d'enregistrement selon la revendication 1, caractérisé en ce que la couche transmettant la lumière  Recording medium according to claim 1, characterized in that the light-transmitting layer (18) est en dioxyde de silicium.(18) is silicon dioxide. 5. Support d'enregistrement selon la revendication 4,  Recording medium according to claim 4, 2467460:2467460: caractérisé en ce que l'épaisseur de la couche transmettant la lumière(le est comprise entre environ 20 manomètres  characterized in that the thickness of the light transmissive layer (the is between about 20 nanometers et environ 150 nanomètres.and about 150 nanometers. 6. Support d'enregistrement selon la revendication 1, caractérisé en ce que la couche absorbant la lumière (20) se compose d'un matériau choisi dans le groupe consistant en titane, rhodium, bismuth, tellurium et  Recording medium according to claim 1, characterized in that the light-absorbing layer (20) consists of a material selected from the group consisting of titanium, rhodium, bismuth, tellurium and alliages à base de tellurium.tellurium-based alloys. 7. Support d'enregistrement selon la revendication 6, caractérisé en ce que l'épaisseur de la couche absorbant la lumière (20) est comprise entre environ 2 nanomètres  Record carrier according to claim 6, characterized in that the thickness of the light absorbing layer (20) is between about 2 nanometers et environ 30 nanomètres.and about 30 nanometers. 8. Support de l'information selon l'une quelconque  8. Information support according to any one of des revendications précédentes, du type o une piste  of the preceding claims, of the type o a track de l'information y est formée, caractérisé en ce que ladite piste se compose d'une séquence d'ouvertures (22) dans la couche absorbant la lumière (20), des variations de la longueur ou de l'ouverture, ou des deux, le long de la piste et l'intervalle entre les ouvertures successives représentant l'information enregistrée.  information is formed therein, characterized in that said track consists of a sequence of apertures (22) in the light-absorbing layer (20), variations in length or aperture, or both along the track and the interval between successive openings representing the recorded information.
FR8012663A 1979-10-09 1980-06-06 OPTICAL VIDEODISK FOR RECORDING AND READING AT TWO DIFFERENT WAVE LENGTHS Withdrawn FR2467460A1 (en)

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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.
CN113380278B (en) * 2018-11-20 2023-03-31 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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