WO1996028818A1 - Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing - Google Patents
Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing Download PDFInfo
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- WO1996028818A1 WO1996028818A1 PCT/GB1996/000212 GB9600212W WO9628818A1 WO 1996028818 A1 WO1996028818 A1 WO 1996028818A1 GB 9600212 W GB9600212 W GB 9600212W WO 9628818 A1 WO9628818 A1 WO 9628818A1
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- thickness
- disk
- spherical aberration
- substrate
- spacer layer
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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
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1372—Lenses
- G11B7/1378—Separate aberration correction lenses; Cylindrical lenses to generate astigmatism; Beam expanders
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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
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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
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/005—Reproducing
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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
- 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
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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
- G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
- G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
- G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers
Definitions
- the present invention relates to optical disks that have multiple data layers and optical disk drives that are operable with such disks.
- Optical data storage systems provide a means for storing great quantities of data.
- the data is accessed by focusing a laser beam to a small spot on the data layer of the optical medium and then detecting the reflected light beam.
- Optical disk drive systems with removable optical disks are the most common form of optical storage.
- Various kinds of such systems are known.
- a ROM (Read Only Memory) system such as a compact disk system (e.g. CD-ROM, CD Audio, CD Video)
- CD-ROM Compact disk system
- a WORM (Write Once Read-Many) system allows the user to write data by making marks, such as pits, in a recording layer of the optical disk. Once the data is recorded onto the disk it cannot be erased. The data in a WORM system is also detected as a change in reflectivity.
- An optical disk having two or more data layers may be accessed at different layers by changing the focal position of the lens.
- IBM's US Patent 5,202,875 describes a multiple data layer optical disk drive system wherein the optical disk comprises either a plurality of substrates, each with a data layer spaced apart by air gaps, or a plurality of data layers in a solid structure.
- US Patent 4,450,553 assigned to U.S. Philips uses a solid structure with multiple data layers, where each data layer is a CD type data layer, in such multiple data layer optical disk drive systems, the light from the laser must pass through one or more of the light-trans issive disk substrates to access the data layers on the different substrates.
- US Patent 5,097,464 assigned to Matsushita describes a multiple data layer CD system that uses a lens with aberration corrected for the data layer farthest from the lens and an optical path length corrector that is inserted into the optical path when the laser spot is focused on data layers closer to the lens.
- IBM's US Patent 5,202,875 describes a multiple data layer optical disk drive system with an active aberration compensator.
- An additional problem in multiple data layer systems is the need to be compatible with conventional single data layer disks, such as CDs.
- conventional Cds use a 1.20 mm thick polycarbonate substrate.
- a multiple data layer CD disk drive must be able to focus a nearly diffraction-limited spot on the data layer of the conventional single data layer disk as well as on the multiple data layers of the newer multiple data layer disk.
- Still another problem that occurs in multiple data layer systems is crosstalk caused by undesirable data, focus error and tracking error signals from adjacent data layers interfering with the signals from the desired data layer. These undesired signals are known as interlayer crosstalk. To avoid this problem it is necessary to maintain a relatively large spacing between the data layers. However, a relatively large spacing between data layers that are separated by solid spacer material increases the overall thickness of the disk and the amount of required active spherical aberration correction, both of which are undesirable.
- optical disk drive that operates with single and multiple data layer disks and that minimizes the effects of spherical aberration and interlayer crosstalk.
- an optical data storage system comprising: a laser light source; an optical data medium comprising a partially light • transmissive first data layer, a light-reflective second data layer, and a light-transmissive spacer layer located between and separating the first and second data layers by the thickness of said spacer layer; a lens located between the laser light source and the first data layer of the medium for focusing the laser light to a spot, the lens having correction for spherical aberration so that the focused spot has approximately minimum spherical aberration when located between the first and second data layers.
- optical data disk of the type readable by laser light transmitted through a lens having correction for spherical aberration
- the disk comprising: a light-transmissive substrate having a thickness tl and a first surface that forms a disk outer face onto which the laser light is incident from the lens; a partially light-transmissive first data layer on the substrate surface opposite said first surface; a light-reflective second data layer; and a light-transmissive spacer layer having a thickness t2 and located between and separating the first and second data layers, the thickness tl of substrate material plus one-half the thickness t2 of spacer layer material being substantially equivalent to the thickness of material corresponding to said correction for spherical aberration of the lens.
- an optical disk drive system comprising: a laser light 3 ⁇ urce; an optical disk comprising (a) a light-transmissive substrate having a first surface that forms a disk outer face onto which the laser light is incident, (b) a partially light-transmissive first data layer on the substrate surface opposite said first surface, (c) a light-reflective second data layer, and (d) a light-transmissive spacer layer located between and separating the first and second data layers by the thickness of said spacer layer; a motor attached to the disk for rotating the disk; a lens located between the laser light source and said first surface of the substrate for focusing the laser light to a spot, the lens having correction for spherical aberration caused by the total substrate thickness plus approximately one-half the spacer layer thickness; and means connected to the lens for moving the lens relative to the disk so the focused spot can be moved from one data layer to another data layer; whereby when the spot is located on the first data layer it possesses spher
- a compact disk (CD) optical disk drive system comprising: a laser light source; a CD optical disk comprising (a) a light-transmissive substrate having a thickness tl and a first surface that forms a disk outer face onto which the laser light is incident, (b) a partially ligh - transmissive first data layer on the substrate surface opposite said first surface, (c) a light-transmissive spacer layer having a thickness t2 and located on the first data layer, and (d) a light-reflective second data layer on the spacer layer and separated from the first data layer by approximately t2; a motor attached to the disk for rotating the disk; a lens located between the laser light source and said first surface of the substrate for focusing the laser light to a spot, the lens having a fixed correction for spherical aberration; and means connected to the lens for moving the lens relative to the disk so the focused spot can be moved from one data layer to another data layer, the fixed s
- an optical data storage disk of the type readable by laser light transmitted through a lens having a correction for spherical aberration corresponding to a fixed thickness of light-transmissive material having a known index of refraction the disk comprising a light-transmissive substrate, a partially light-transmissive first data layer, a light- reflective second data layer, and a light-transmissive spacer layer located between and separating the first and second data layers, the thickness of the light-transmissive substrate plus one-half the thickness of the spacer layer being substantially equivalent to said fixed thickness of light-transmissive material having said known index of refraction for which the lens is spherical aberration corrected.
- a multiple data layer optical disk drive system that has fixed aberration correction and uses a disk with maximum interlayer spacing for reduced interlayer crosstalk.
- the multiple data layer disk has a substrate with a thickness that is reduced by approximately one-half the thickness of the spacer layer that separates the first and last data layers.
- the disk is designed to operate with a lens that has spherical aberration correction to compensate for the thickness of a conventional single data layer disk. This allows the disk drive to handle multiple data layer disks as well as to be backward compatible and thus handle conventional single data layer disks.
- the thickness of the substrate material plus one-half the thickness of the spacer layer material is equivalent, for purposes of spherical aberration correction, to the thickness of the substrate material used in the conventional single data layer disk.
- the focused spot with minimum spherical aberration is thus located at the middle of the spacer layer rather than on the first data layer.
- the spacer layer thickness is selected so that when the focused spot is located on either the first or last data layer there is some deliberately designed spherical aberration, although an amount that is acceptable. As a result the thickness of the spacer layer can be significantly increased to thereby reduce interlayer crosstalk.
- the substrate thickness and spacer layer thickness are selected and then the lens is corrected for spherical aberration corresponding to the thickness of substrate material plus one-half the thickness of spacer layer material.
- Fig. 1 is a schematic diagram of an optical disk drive system embodying the present invention in the form of a CD system
- Fig. 2 is a schematic diagram of the optical head and two-layer disk of the optical disk drive system
- Fig. 3 is a block diagram of a controller system of the optical disk drive system
- Fig. 4 is a graph illustrating the light intensity of a focused spot as a function of position across the beam for two cases: Curve A with minimal spherical aberration and Curve B with significant spherical aberration;
- Fig. 6 is a sectional view of the two layer disk illustrating the spot with minimum spherical aberration located in the middle of the spacer layer;
- Fig. 8 is a sectional view of an air-incident two layer disk with a thin dust cover illustrating the spot with minimum spherical aberration located in the middle of the spacer layer.
- Fig. 1 is a schematic diagram of an optical disk data storage system according to the present invention designated by the general reference number 10.
- Systeir 10 will be explained in terms of a CD optical disk drive syster .
- System 10 includes an optical data storage disk 12 which is preferably removably mounted on a clamping spindle 14 as is known in the art.
- Spindle 14 is attached to a spindle motor 16, which m turn is attached to a system chassis 20.
- Motor 16 rotates spindle 14 and disk 12.
- An optical head 22 is positioned below disk 12. Head 22 is attached to an arm 24, which in turn is connected to an actuator device such as a voice coil motor 26. Voice coil motor 26 is attached to chassis 20 and moves arm 24 and head 22 in a radial direction below disk 12.
- Fig. 2 shows a schematic diagram of one embodiment of the optical head 22 and disk 12 of Fig. 1.
- Optical head 22 includes a laser diode 200, which may be a gallium-aluminum-arsenide diode laser producing a primary beam of light 202 at approximately 780 nanometers wavelength.
- Beam 202 is first diffracted by grating 201 to produce two secondary beams for tracking, in addition to the primary data beam, and then collimated by lens 203.
- the resulting three-component beam 204 then passes to a beamsplitter 205.
- a portion of beam 204 is reflected by beamsplitter 205 to a lens 206 and an optical detector 207.
- Detector 207 is used to monitor the power of laser beam 204.
- Beam 204 from beamsplitter 205 next passes to and is reflected by a mirror 208. Beam 204 then passes through a focus lens 210 and is focused to a diffraction-limited spot.
- Lens 210 is mounted in a holder 214, the position of which is adjusted relative to disk 12 by a focus actuator motor 216, which may be a voice coil motor. Movement of the lens 210 by the focus actuator moves the focused spot between the two data layers 52, 62 of disk 12.
- a portion of the light beam 204 is reflected from a data layer 52, 62 as a reflected beam 220.
- Beam 220 returns through lens 210 and is reflected by mirror 208.
- beam 220 is directed through an astigmatic lens 232 and onto a multielement optical detector 234.
- Fig. 3 is a block diagram of a controller system of the optical disk drive system and is designated by the general reference number 300
- the multielement detector 234 (Fig. 2) generates output signals that provide a data signal, a focus error signal (FES) , and a tracking error signal (TES) . These signals are amplified by signal amplifier 236 and sent directly to controller 314.
- a peak detector 310 also receives the FES, and a peak detector 312 also receives the TES from amplifier 236.
- Controller 314 also receives input signals from FES peak detector 310, TES peak detector 312, and laser power detector 207.
- Controller 314 is a microprocessor-based disk drive controller.
- Controller 314 is also connected to and controls the laser 200, hea ⁇ motor 26, spindle motor 16, and focus actuator motor 216.
- the disk 12 is shown in cross-section.
- the disk 12 comprises a light-transmissive substrate 40, typically polycarbonate.
- a first surface 41 of substrate 40 faces lens 210 and is the side onto which the light is incident.
- the opposite surface of substrate 40 has formed on it a first data layer 52.
- Data layer 52 is a pattern of pits or depressions formed into the surface of substrate 40 and covered with a film of partially light-transmissive material.
- Data layer 52 is formed by conventional injection molding, embossing, or photopolymer replication.
- Substrate 40 and first data layer 52 are similar to that m conventional CDs, with the exception that the film covering the pattern of pits on the substrate surface is partially light-transmissive rather than totally reflective.
- This film of material can be formed of any conventional semiconductor material (e.g., amorphous Si, SiC, GaSb) , dielectric material (e.g., Zr0 2 , SiN) , or metallic material (e.g., Al, Au) . These materials can be deposited by sputtering or evaporation, as is known in the art, and have a thickness in the range of 30-3000 Angstroms.
- a light transmissive spacer layer 44 is formed over data layer 52.
- the spacer layer can be formed of a photopolymer material deposited by spin-coating.
- the spacer layer 44 can be formed by a lamination process, i.e., gluing a thin plastic sheet, embossed with data layer 62, onto the covering film of the data layer 52 on substrate 40.
- the surface of spacer layer 44 opposite the surface in contact with data layer 52 has formed on it a second data layer 62
- Data layer 62 also comprises a pattern of pits, formed on the surface of the spacer layer 44, and a covering film of light reflective material, such as an aluminum alloy.
- the aluminum alloy covering film is preferably totally reflective if the data layer 62 is the last data layer in the multiple data layer disk, and has a typical thickness in the range of 100 1000 Angstroms.
- the embossed pattern of data layer 62 can be formed by a photopolymerization process with a stamper in contact with the polymer, with the polymer cured by ultraviolet radiation. If the spacer layer is formed by lamination, the data layer 62 can be pre-embossed onto the plastic sheet before the sheet is glued to substrate 40. Typically the depth of the pits in the embossed patterns in data layers 52, 62 is in the range of 1000 to 2000 Angstroms. Finally, a protective layer 70 of a photopolymer is formed over data layer 62 by spm-coating followed by curing.
- the two-layer CD as shown in Fig. 2 is a dual data layer disk.
- the substrate 40 has a thickness tl and is formed of light transmissive material with an index of refraction nl
- Spacer layer 44 has a thickness t2 and is formed of light transmissive material with an index of refraction n2. Additional data layers may be used in the disk 12 For example, additional embossed patterns and partially light transmissive films can be formed between the first and second data layers 52, 62
- Controller 314 controls motor 16 that rotates disk 12 and motor 26 that moves optical head 22 to the proper position below disk 12. Laser 200 is energized to read data from disk 12.
- the beam 204 is focused by lens 210 to a nearly diffraction- limited spot and this focused spot is located on the desired one of the data layers 52, 62.
- the reflected beam 220 returns and is directed to the multielement detector 234 by the astigmatic lens 232.
- the FES, TES, and data signals are output by detector 234 and amplified by amplifier 236 (Fig. 3) .
- the FES is used by controller 314 m a conventional servo control technique to control focus actuator motor 216 so that lens 210 maintains the spot on the desired data layer (e.g., data layer 52) as the disk 12 rotates.
- the controller 314 When it is desired to read data from data layer 62, the controller 314 signals focus actuator motor 216 to move the lens so the spot is moved from data layer 52 to data layer 62. when the spot is located on data layer 62, the light from lens 210 traverses the entire thickness tl of substrate 40 and thickness t2 of spacer layer 44.
- Fig. 4 is a graph of the light intensity of the focused spot as a function of lateral position from the center of the spot for two different spots: one having minimum spherical aberration and one having significant spherical aberration due to a non-optimum substrate thickness. Curve A in Fig.
- FIG. 4 represents a spot with minimum spherical aberration, and is an essentially Gaussian distribution of light intensity.
- the diffraction limited spot diameter is defined as the full width at half the maximum intensity amplitude, and is depicted for Curve A in Fig. 4.
- Curve B in Fig 4 represents a spot with spherical aberration and illustrates a lower peak intensity and the presence of side lobes.
- the spot on the data layer will possess spherical aberration. This is undesirable because the data, focus error and tracking error signals all rely upon having maximum optical resolution.
- the solid line is the Strehl ratio for material with an index of refraction of 1.57 (e.g., polycarbonate) and the dashed line is the Strehl ratio for material with an index of refraction of 1.10.
- the spacer layer 44 is also of material with an index of refraction near 1.57, then the spacer layer can not be any thicker than approximately 0.125 mm or the spot will have unacceptably high spherical aberration when it is focused on data layer 62.
- the thickness of the spacer layer can not be larger than approximately 0.05 mm.
- the multiple data layer optical disk drive system is designed so that the focused spot with minimum spherical aberration is not located on any data layer. Instead the spot is located preferably at the midpoint between the two data layers nearest and farthest from the lens.
- the disk drive is designed so that the spot with minimum spherical aberration is located at the middle of spacer layer 44.
- the focused spot with minimum spherical aberration is illustrated as being located at approximately the middle of spacer layer 44 (i.e., t2/2 distance from both data layers 52 and 62).
- the amount of material traversed by the light to this point is approximately the tl thickness of substrate 40, with index of refraction of nl, and one-half the thickness of spacer layer 44 (t2/2) , with index of refraction of n2.
- the substrate 40 has a thickness not equal to the conventional substrate thickness, but to the conventional thickness less t2/2 of the spacer layer 44 thickness.
- the substrate 40 thickness tl is approximately 1.075 mm and spacer layer 44 thickness t2 is approximately 0.250 mm.
- the substrate 40 thickness tl would be approximately 1.15 mm and spacer layer 44 thickness t2 would be approximately 0.10 mm.
- the spacer layer 44 material is preferably a polymer which has an index of refraction sufficiently similar to that of polycarbonate that it is only a second order effect in the spherical aberration correction and need not be factored into the selection of substrate thickness tl. However, if the index of refraction of the spacer layer is different from that of the substrate, the thickness tl of the substrate is adjusted so that tl of substrate material with index of refraction nl and t2/2 of spacer layer material with index of refraction n2 together are equivalent to the thickness of material to which the lens is spherical aberration corrected.
- the thickness t2 of spacer layer 44 is selected based on the minimum acceptable Strehl ratio, which in turn depends on the N.A. of the lens and the index of refraction of the substrate material.
- the thickness t2 is selected so that t2/2 corresponds to the maximum thickness variation where the spherical aberration is still acceptable.
- the result is a doubling of the spacer layer thickness over what would be the case if the focused spot with minimum spherical aberration were located on the first data layer.
- the effect of interlayer crosstalk is substantially reduced while the amount of spherical aberration on both data layers is still acceptable.
- An advantage of this embodiment of the present invention is that since the lens remains spherical aberration corrected for the conventional substrate thickness of a single data layer optical disk, the optical disk drive can also operate with conventional single data layer disks.
- the substrate and spacer layer thicknesses are selected to optimize performance of the multiple data layer disk and the lens is spherical aberration corrected for the selected tl of substrate with index of refraction nl and t2 of spacer layer with index of refraction n2.
- the conventional 1.20 mm substrates can be used for the two data layer systerr and the spacer layer can be made 0.25C mm thick.
- the method of correcting lenses for known spherical aberration in systems having a piano-parallel substrate is a well-known technique.
- the wavelength of the light and the thicknesses and indices of refraction of the material through which the light must traverse are used to generate a polynomial equation that represents the shape of the lens. This method is described, for example, by . Kingslake, Lens Design Fundamentals, pp. 119-122 and 205-208, Academic Press, 1978, and is not part of the present invention.
- the spacer layer thickness can be doubled to 0.13 mm.
- a Strehl ratio of 0.9 has been used.
- the multiple data layer disk shown in Fig. 6 is illustrated as a solid structure where the outer layers are the substrate 40 and protective layer 70.
- the substrate 70 is polycarbonate with a thickness of either 1.20 mm or 1.20 mm less t2/2, depending on the embodiment.
- the multiple data layer disk may also be fabricated by bonding two thinner single data layer disks together.
- the protective layer 70 is a second substrate identical to substrate 40.
- two substrates of 0.60 mm thickness and each having a data layer are bonded together with a light-transmissive material, such as a conventional photopolymer, that serves as the spacer layer.
- a light-transmissive material such as a conventional photopolymer
- the data layer on the substrate closest to lens 210 has a partially light-transmissive covering film over its pit pattern and the data layer on the substrate farthest from lens 210 has a totally light-reflective covering film on its pit pattern.
- Fig. 8 illustrates the invention with an alternative type of multiple data layer disk 90.
- the disk 90 includes an aluminum disk blank 91, a data layer 92 farthest from lens 210 formed on disk blank 91, a spacer layer 93 on data layer 92 and a data layer 94 nearest to lens 2 C formed on spacer layer 93.
- a plastic ring 95 is bonded to aluminum disk blank 91 and extends around the outer perimeter of disk blank 91.
- the ring 95 supports a transparent plastic dust cover 96.
- the dust cover 96 is typically 100 microns thick and is stretched across and bonded to ring 95.
- the dust cover 96 forms an air gap of 0.2-2.0 mm between it and the data layer 94.
- Both data layers 92, 94 are recordable phase change WORM data layers, typically formed of In-Sb-Sn.
- the first data layer 94 closest to lens 210 is 60-120 Angstroms thick and is thus by its thickness partially light-transmissive.
- the second data layer 92 farthest from lens 210 is 400-2000 Angstroms thick and thus has an increased reflectivity over data layer 94.
- the spacer layer 93 is a spin-coated and cured photopolymer film with a typical thickness of 0.05-0.15 mm. As shown m Fig. 8 the focused spot with minimum spherical aberration is located at the middle of spacer layer 93.
- the "substrate" through which the light passes to the data layers 92, 94 is the dust cover 96.
- the spherical aberration correction for the lens 210 is the correction needed due to passage of the light through the thickness of dust cover 96 (with its index of refraction nl) and through one-half the thickness of spacer layer 93 (with its index of refraction n2) . Passage of light through air does not introduce any spherical aberration so the air gap between dust cover 96 and first data layer 94 does not figure into the spherical aberration correction for the lens 210.
- the invention has been described with a two-layer disk. However, the invention is also applicable where there are additional data layers located between the first data layer (the one nearest the lens) and the second or last data layer (the one farthest from the lens) .
- the drive would be designed so that the lens is still spherical aberration corrected for tl plus t2/2 (where t2 is the thickness of the solid light-transmissive material between the nearest and farthest data layers) , and the nearly diffraction-limited spot would be located between the fourth and fifth data layers from the lens.
- the invention has also been described relative to a CD system. However the invention is fully applicable with any multiple data layer optical disk, such as magneto-optic, phase change, or ablative write-once/read-many (WORM) disks.
- any multiple data layer optical disk such as magneto-optic, phase change, or ablative write-once/read-many (WORM) disks.
Abstract
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Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CZ19972735A CZ293793B6 (en) | 1995-03-13 | 1996-02-01 | Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing |
CA002215323A CA2215323C (en) | 1995-03-13 | 1996-02-01 | Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing |
AT96901436T ATE197652T1 (en) | 1995-03-13 | 1996-02-01 | MULTI-LAYER OPTICAL DISK DRIVE SYSTEM WITH FIXED ABERRATION CORRECTION AND OPTIMAL INTERLAYER SPACING |
PL96322062A PL179637B1 (en) | 1995-03-13 | 1996-02-01 | Disk drive for an optical disk with multiple layers of data, predetermined aberration correction and optimum interlayer distance |
DE69610997T DE69610997T2 (en) | 1995-03-13 | 1996-02-01 | MULTILAYER OPTICAL DISK DRIVE SYSTEM WITH FIXED ABERRATION CORRECTION AND OPTIMUM INTERLAY SPACING |
EP96901436A EP0886857B1 (en) | 1995-03-13 | 1996-02-01 | Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/403,166 US5625609A (en) | 1995-03-13 | 1995-03-13 | Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing |
US08/403,166 | 1995-03-13 |
Publications (1)
Publication Number | Publication Date |
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WO1996028818A1 true WO1996028818A1 (en) | 1996-09-19 |
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Application Number | Title | Priority Date | Filing Date |
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PCT/GB1996/000212 WO1996028818A1 (en) | 1995-03-13 | 1996-02-01 | Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing |
Country Status (18)
Country | Link |
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US (1) | US5625609A (en) |
EP (1) | EP0886857B1 (en) |
JP (1) | JP2825107B2 (en) |
KR (1) | KR100188488B1 (en) |
CN (2) | CN1053515C (en) |
AT (1) | ATE197652T1 (en) |
BR (1) | BR9600345A (en) |
CA (1) | CA2215323C (en) |
CZ (1) | CZ293793B6 (en) |
DE (1) | DE69610997T2 (en) |
ES (1) | ES2153088T3 (en) |
HK (1) | HK1032656A1 (en) |
HU (1) | HU224498B1 (en) |
MY (1) | MY112200A (en) |
PL (1) | PL179637B1 (en) |
RU (1) | RU2190882C2 (en) |
TW (2) | TW549539U (en) |
WO (1) | WO1996028818A1 (en) |
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EP0867874A2 (en) * | 1994-12-28 | 1998-09-30 | Matsushita Electric Industrial Co., Ltd. | Optical recording medium having dual information surfaces |
EP0835508B1 (en) * | 1995-06-30 | 1999-12-01 | International Business Machines Corporation | Optical data storage system with multiple write-once phase-change recording layers |
EP1127679A2 (en) * | 1995-12-20 | 2001-08-29 | Kabushiki Kaisha Toshiba | Information recording medium, method for manufacturing the medium, and apparatus for manufacturing the medium |
US6990055B1 (en) | 1999-06-22 | 2006-01-24 | Matsushita Electric Industrial Co., Ltd. | Optical disc drive for controlling reproduction of an optical disc having a plurality of data layers |
EP1630793A3 (en) * | 2004-08-31 | 2008-01-16 | TDK Corporation | Optical recording medium |
CN100412965C (en) * | 2005-04-04 | 2008-08-20 | 索尼株式会社 | Disk drive apparatus and spherical aberration correcting method |
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Also Published As
Publication number | Publication date |
---|---|
ATE197652T1 (en) | 2000-12-15 |
JPH10500525A (en) | 1998-01-13 |
CZ273597A3 (en) | 1997-12-17 |
JP2825107B2 (en) | 1998-11-18 |
US5625609A (en) | 1997-04-29 |
EP0886857B1 (en) | 2000-11-15 |
DE69610997T2 (en) | 2001-04-19 |
RU2190882C2 (en) | 2002-10-10 |
CA2215323C (en) | 2002-03-19 |
ES2153088T3 (en) | 2001-02-16 |
HUP9801981A3 (en) | 2002-11-28 |
EP0886857A1 (en) | 1998-12-30 |
MY112200A (en) | 2001-04-30 |
HU224498B1 (en) | 2005-10-28 |
TW364993B (en) | 1999-07-21 |
KR960035485A (en) | 1996-10-24 |
HK1032656A1 (en) | 2001-07-27 |
CN1135636A (en) | 1996-11-13 |
HUP9801981A2 (en) | 1998-12-28 |
CZ293793B6 (en) | 2004-08-18 |
PL322062A1 (en) | 1998-01-05 |
TW549539U (en) | 2003-08-21 |
KR100188488B1 (en) | 1999-06-01 |
BR9600345A (en) | 1998-01-27 |
CN1127066C (en) | 2003-11-05 |
CA2215323A1 (en) | 1996-09-19 |
CN1053515C (en) | 2000-06-14 |
PL179637B1 (en) | 2000-10-31 |
DE69610997D1 (en) | 2000-12-21 |
CN1274914A (en) | 2000-11-29 |
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