14.
    发明专利
    未知

    公开(公告)号:DE69818166T2

    公开(公告)日:2004-07-22

    申请号:DE69818166

    申请日:1998-06-25

    Applicant: IBM

    Abstract: This invention provides phase change media for optical storage based on semiconductors of nitrides of the column III metals. The surface of thin films of these wide bandgap semiconductors may be metallized (by desorption of the nitrogen) by irradiating with photons of energy equal to, or greater than the band gap of these materials, and with power densities beyond a critical threshold value. As a consequence of such writable metallization, these materials are excellent candidates for write once, read many times storage media since the differences in the reflectivity between the metal and its corresponding wide gap nitride are very large. Furthermore, once the nitrogen is desorbed, the written metallic phase can no longer revert back to the nitride phase and hence the media is stable and is truly a write-once system. Additional advantages offered by these materials over present day phase change media include higher differences in reflectivity contrast and suitability for use with short wavelength laser diodes (460 nm and lower) which are expected to be introduced into optical recording technology in the next 5 years. The band gap of alloys of nitrides of column III metals can be tuned by changing the relative fractions of the column III metals to continuously vary the band gap so as to be compatible with lasers having photon energies within the range. The low absorptivity and hence high transmissitivity, at the appropriate recording wavelength, of the starting phase also offers the potential application of these materials in a multiple-recording-layer format.

    16.
    发明专利
    未知

    公开(公告)号:ES2153088T3

    公开(公告)日:2001-02-16

    申请号:ES96901436

    申请日:1996-02-01

    Applicant: IBM

    Abstract: A multiple data layer optical disk drive system has fixed aberration correction and uses a disk with maximum interlayer spacing for reduced interlayer crosstalk. In one embodiment 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 (which may have a different index of refraction than the substrate 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. In another embodiment that 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.

    DRIVING SYSTEM OF OPTICAL DISK WITH A GREAT AMOUNT OF DATA LAYERS, WITH CORRECTION OF FIXED ABERATION AND OPTIMIZED DISTRIBUTION OF INTERMEDIATE LAYERS

    公开(公告)号:CZ9702735A3

    公开(公告)日:1997-12-17

    申请号:CZ273597

    申请日:1996-02-01

    Applicant: IBM

    CPC classification number: G11B7/24 G11B7/005 G11B2007/0013

    Abstract: A multiple data layer optical disk drive system has fixed aberration correction and uses a disk with maximum interlayer spacing for reduced interlayer crosstalk. In one embodiment 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 (which may have a different index of refraction than the substrate 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. In another embodiment that 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.

    OPTICAL DATA STORAGE SYSTEM WITH MULTIPLE WRITE-ONCE PHASE-CHANGE RECORDING LAYERS

    公开(公告)号:CA2220879A1

    公开(公告)日:1997-01-23

    申请号:CA2220879

    申请日:1996-03-08

    Applicant: IBM

    Abstract: An optical disk drive (10) uses an optical disk (12) with spatially separate d multiple phase-change WORM recording layers (51, 66). The optical disk has a light transmissive substrate onto which the laser light is incident. The substrate supports at least two spatially separated multi-film recording stacks (90, 92), each stack including an active recording layer of phase- change WORM material. The disk is either an air-gap (78) structure wherein each recording stack is supported on a separate substrate (50, 56) and the substrates (50, 56) are separated by an air-gap (78), or a solid structure wherein a solid light transmissive spacer layer (22) separates the recording stacks (90, 92). Each of the recording stacks (90, 92) located between the substrate (50) on which the laser light is incident and the farthest recordi ng stack includes an active phase-change recording layer (51) and an optical interference film (53) in contact with the recording layer (51). The recordi ng layer (51) is made sufficiently thin to have good light transmissivity, but at this low thickness, without any other layers, is not sufficiently reflective to act as a recording layer with suitable servo and recording performance. T he optical interference film (53) in contact with the recording layer (51) has a high index ofrefraction relative to the adjacent recording layer (51) and spacer (122) to increase the optical interference effect in the recording stack (90). The optical interference film (53) optimizes the contrast, reflectivity and transmissivitzy of the recording stack. The optical interference film (53) has low absoprtion so that laser light can pass throu gh it to focus on a farther recording layer (66). This allows the farther recording layers (66) to be written using reasonable laser power.

    Multiple data layer optical disk drive system with fixed aberration correction and optimum interlayer spacing

    公开(公告)号:CZ293793B6

    公开(公告)日:2004-08-18

    申请号:CZ273597

    申请日:1996-02-01

    Applicant: IBM

    Abstract: The invented multiple data layer optical disk drive system has fixed aberration correction and uses a disk (12) with maximum interlayer spacing for reduced interlayer crosstalk. In one embodiment the multiple data layer disk (12)¿has a substrate with a thickness that is reduced by approximately one-half the thickness of the spacer layer (44) that separates the first and last data layers. The disk (12) is designed to operate with a lens (210) that has spherical aberration correction to compensate for the thickness of a conventional single data layer disk (12). 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 (which may have a different index of refraction than the substrate 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 one 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. In another embodiment, 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.

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