WO2022258062A1 - 多层记录介质的数据写入方法及其读写装置 - Google Patents

多层记录介质的数据写入方法及其读写装置 Download PDF

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Publication number
WO2022258062A1
WO2022258062A1 PCT/CN2022/098254 CN2022098254W WO2022258062A1 WO 2022258062 A1 WO2022258062 A1 WO 2022258062A1 CN 2022098254 W CN2022098254 W CN 2022098254W WO 2022258062 A1 WO2022258062 A1 WO 2022258062A1
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WIPO (PCT)
Prior art keywords
servo
light
layer
recording layer
writing
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PCT/CN2022/098254
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English (en)
French (fr)
Inventor
邹宇豪
马建设
徐君
邢田
刘明源
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华为技术有限公司
清华大学深圳国际研究生院
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Publication of WO2022258062A1 publication Critical patent/WO2022258062A1/zh

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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
    • G11B7/2403—Layers; Shape, structure or physical properties thereof
    • G11B7/24035—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
    • G11B7/2403—Layers; Shape, structure or physical properties thereof
    • G11B7/24056—Light transmission layers lying on the light entrance side and being thinner than the substrate, e.g. specially adapted for Blu-ray® discs
    • 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
    • G11B7/2403—Layers; Shape, structure or physical properties thereof
    • G11B7/24065—Layers assisting in recording or reproduction below the optical diffraction limit, e.g. non-linear optical layers or structures

Definitions

  • Various embodiments of the present disclosure relate to the field of optical storage, and more specifically relate to a method for writing data into a multi-layer recording medium and a read-write device thereof.
  • multi-layer storage can effectively increase storage density
  • the multi-layer structure makes read and write operations and servo control more difficult.
  • the purpose of the present disclosure is to provide an improved method for writing data into a multi-layer recording medium and a read-write device thereof, which can help increase the number of recording layers and storage capacity of a single disc.
  • the writing/serving solution of the present disclosure can also ensure high-speed reading and writing on the basis of increased disc capacity.
  • a data writing method for a multi-layer recording medium at least includes a first recording layer and a second recording layer, and the method includes: using data writing light to write data in the second recording layer, wherein the first recording layer on which the data is written is incident on layer of light as the servo light for the data writing light.
  • the data writing method of the present disclosure provides the idea of using the light incident on the previous recording layer on which the data is written as the servo light, which helps to simplify the servo scheme and makes the servo of the disk more free. Since the light incident on the recording layer can be used as servo light to write data to another recording layer, even if the number of storage layers of the recording medium increases, high-speed reading and writing can still be achieved, which helps to increase the recording capacity of a single disc. layers and storage capacity.
  • the multilayer recording medium further includes a servo layer
  • the method further includes: writing data on the first recording layer using first writing light, wherein the light incident on the servo layer is Servo light as the first writing light.
  • the first recording layer and the second recording layer are adjacent to each other, and the second recording layer is located above the first recording layer.
  • the data writing light and its corresponding servo light have the same wavelength.
  • the first recording layer is a recording layer adjacent to the servo layer, and the data writing sequence of the multiple recording layers is layer-by-layer writing starting from the first recording layer.
  • the movement track of the servo light and the corresponding data writing light keep consistent.
  • the servo layer includes a wobbled groove track
  • the writing data on the first recording layer using the first writing light includes: controlling the edge of the servo light corresponding to the first writing light The oscillating groove orbits.
  • the writing data on the second recording layer using the data writing light includes: controlling the servo light corresponding to the data writing light to move along the data track of the first recording layer .
  • the wavelengths are all 405 nm.
  • a read/write device includes: a servo optical path assembly, configured to irradiate servo incident light to a first recording layer on which data is written in a multi-layer recording medium, and receive servo reflected light reflected by the first recording layer, wherein the The multiple recording medium includes at least the first recording layer and the second recording layer; a main optical path assembly for irradiating data writing light to the second recording layer; and a control device for using the servo reflected light as A servo light controls the data writing light to write data to the second recording layer.
  • control device is further configured to control the movement trajectories of the data writing light and the corresponding servo light to be consistent during the writing process.
  • the main optical path assembly is also used to irradiate the first writing light to the first recording layer
  • the servo optical path assembly is also used to irradiate another servo light to the servo layer of the multi-layer recording medium.
  • incident light, and receive another servo reflected light reflected by the servo layer; the control device is also used to control the first writing light to the second A recording layer writes data.
  • the main optical path assembly includes a first objective lens adapted to focus the data writing light onto a second recording layer on the multilayer recording medium; the servo optical path assembly A second objective lens is included, the second objective lens is adapted to focus the servo incident beam onto a first recording layer on the multilayer recording medium.
  • the first objective lens and the second objective lens are disposed on the same torquer, and both are adapted to move synchronously with the movement of the torquer.
  • the read-write device further includes: a laser source, used to emit an initial laser beam; a first beam splitter, used to divide the initial laser beam into a main incident beam and a servo incident beam; a first polarization A beam splitter, located between the first beam splitter and the first objective lens, is used for transmitting the main incident light beam with a first polarization, and the main incident light beam is used as the data writing light.
  • the read-write device further includes: a first compensation lens group, located between the first polarizing beam splitter and the first objective lens, and operable to compensate the focal point of the main incident light beam Refractive index mismatches caused by depth variations within the multilayer recording medium.
  • a read/write device for a multi-layer recording medium includes: a laser source, used to emit an initial laser beam; a first beam splitter, used to divide the initial laser beam into a main incident beam and a servo incident beam; a first objective lens, used to split the main incident beam focusing an incident light beam to a first position on the multilayer recording medium; and a second objective lens for focusing the servo incident light beam to a second position on the multilayer recording medium, and collecting images from the second position of the servo reflected beam, said second position being different from said first position; wherein said first objective lens and said second objective lens are arranged on the same torquer, and both are adapted to accompany said torquer move synchronously.
  • the read-write device further includes: a first polarization beam splitter, located between the first beam splitter and the first objective lens, for transmitting the main incident light beam with a first polarization, and reflecting said main reflected beam having a second polarization.
  • the read-write device further includes: a second polarization beam splitter, located between the first beam splitter and the second objective lens, for reflecting the servo incident light beam with the first polarization, and transmitting said servo reflected beam having a second polarization.
  • the read-write device further includes: a first compensation lens group, located between the first polarizing beam splitter and the first objective lens, and operable to compensate the focal point of the main incident light beam Refractive index mismatches caused by depth variations within the multilayer recording medium.
  • the read/write device further includes: a first detector, configured to receive the main reflected beam reflected from the first polarizing beam splitter, and output an indication indicating that the main incident beam is on the multi-layer recording medium A first detection result on the focus position and/or shape.
  • the read/write device further includes: a second detector arranged to receive the servo reflected light beam transmitted from the second polarization beam splitter, and output an indication indicating that the servo incident light beam is within the multiple A second detection of the focal position and/or shape on the layer records the medium.
  • the read-write device further includes: a first 1/4 wave plate, located between the first polarization beam splitter and the first objective lens, to generate the main reflected beam of a second polarization.
  • the read-write device further includes: a second 1/4 wave plate, located between the second polarization beam splitter and the second objective lens, to generate The servo reflected beam of a second polarization.
  • the read/write device further includes: a second beam splitter, located between the first beam splitter and the first polarizing beam splitter, for receiving from the first beam splitter splitting a portion of light from the main incident beam; and a third detector configured to detect the portion of light from the second beam splitter and output a light intensity indicative of a laser intensity of the initial laser beam detection results.
  • the read/write device further includes: a second compensating lens group, located between the second polarizing beam splitter and the second objective lens, and operable to compensate the focal point of the servo incident light beam Refractive index mismatches caused by depth variations within the multilayer recording medium.
  • a second compensating lens group located between the second polarizing beam splitter and the second objective lens, and operable to compensate the focal point of the servo incident light beam Refractive index mismatches caused by depth variations within the multilayer recording medium.
  • Fig. 1 shows a schematic structural diagram of an exemplary multi-layer recording medium.
  • Fig. 2 shows a schematic structural diagram of another exemplary multi-layer recording medium.
  • FIG. 3 shows an exemplary read and write optical circuit arrangement for the multi-layer recording medium shown in FIG. 2 .
  • FIG. 4 shows a block diagram of a read-write system for a multi-layer recording medium according to an exemplary embodiment of the present disclosure.
  • FIG. 5 shows a schematic flowchart of a method embodying the writing and servo concepts of a multi-layer recording medium according to an exemplary embodiment of the present disclosure.
  • FIG. 6 shows a schematic diagram of a write/servo process for a multi-layer recording medium according to an example embodiment of the present disclosure.
  • FIG. 7 briefly depicts how to use the laser reading and writing module OPU to perform the exemplary reading and writing process of the exemplary embodiment in FIG. 6 .
  • FIG. 8 shows a schematic diagram of a first exemplary read and write optical path for a multi-layer recording medium according to an exemplary embodiment of the present disclosure.
  • FIG. 9 shows a schematic diagram of a second exemplary read and write optical path for a multi-layer recording medium according to an exemplary embodiment of the present disclosure.
  • FIG. 10 shows a schematic diagram of a third exemplary read and write optical path for a multi-layer recording medium according to an exemplary embodiment of the present disclosure.
  • FIGS. 1 to 4 the schematic structure of a conventional multi-layer recording medium and its optical path for reading and writing will first be introduced with reference to FIGS. 1 to 4 , so as to provide an understanding of existing solutions. It should be noted here that these introductions do not imply an acknowledgment or acquiescence that the introduced existing solutions are prior art in this field.
  • FIG. 1 shows a structural diagram of an exemplary multilayer recording medium.
  • an exemplary multi-layer recording medium such as an optical disc may include two recording layers having a wobble structure, each layer including various media layers.
  • the multi-layer dielectric layer may include, for example, a phase-change material layer such as GeSbTe and a reflective layer such as ZnS-SiO2.
  • a phase-change material layer such as GeSbTe
  • a reflective layer such as ZnS-SiO2
  • the phase-change material layer can be converted from a crystalline state to an amorphous state, which is accompanied by a change in refractive index, thereby recording data.
  • a reflective layer such as ZnS-SiO2 can also reflect signals, and the information carried by the reflected signals may include address, clock and other information modulated in the wobble structure.
  • the tracking servo can be accomplished using an auxiliary driver, but a reflective layer such as ZnS-SiO2 in each recording layer will reflect a part of the laser energy. If you want to increase the storage capacity, you can increase the number of recording layers. However, the lower the recording layer, the lower the energy reflected back to the detector, which limits the increase in the number of recording layers.
  • recording storage media of another structure as shown in FIG. 2 have been proposed.
  • the rest of the layers for example, up to 16 layers
  • the concave-convex structure of the wobble structure does not need to be prepared layer by layer in these recording layers, which simplifies the manufacturing process of the disc.
  • the reflectivities of recording layers A and B are only 0.7% and 1.5%, respectively, which enables the number of recording layers to be increased from 4 layers for Blu-ray recording media up to, for example, 16 layers, which greatly increases The storage capacity of a single disk.
  • FIG. 3 is an exemplary read and write optical path for implementing the multilayer optical disc structure shown in FIG. 2 .
  • the laser light emitted by the laser LD1 with a wavelength of 405 nm blue light can be used as the writing light.
  • the signal obtained by the photodiode 1 can be used as a feedback signal to control the movement of the torquer along the z-axis to complete tasks such as layer selection, focusing, and servo.
  • the tracking servo can be accomplished by red light emitted by laser LD2 such as 655nm red light wavelength.
  • the laser LD1 with a wavelength of 655nm may not work, and the written data may be used as a signal feedback source for the tracking servo signal to control the servo of the torquer in the radial direction of the disc, thereby reading out the data.
  • the read-write optical path in FIG. 3 needs to use two different wavelengths of light such as 405nm and 655nm at the same time, when designing the objective lens, only one wavelength (for example, red light wavelength) can be used to achieve perfect focus.
  • another wavelength there may be a problem of refractive index mismatch when selecting layers.
  • the reading and writing optical path in Fig. 3 compensates the refractive index mismatch caused by the change of the focal depth by adjusting the position of the adjusting lens RL1.
  • the read/write optical path in FIG. 3 can still ensure the feasibility of the read/write operation on the multi-layer recording medium based on the read/write servo principle, the read/write optical path in FIG. 3 still has the following deficiencies.
  • the solution in Figure 3 needs to use red light as servo light and blue light as writing light.
  • the Airy disk of red light is larger than that of blue light. Accordingly, only DVD standard wobble tracks can be selected as the servo layer. DVDs have a larger track pitch than the Blu-ray standard, so areal density will drop, reducing storage capacity.
  • the purpose of the present disclosure is to provide an improved read/write/servo scheme for multi-layer recording media and corresponding optical paths, which can not only effectively support the increase in the storage capacity of a single disk, but also support multi-layer recording media (Even recording media with more than 16 layers) high-speed reading and writing.
  • multi-layer recording media Electro recording media with more than 16 layers
  • the difficulty of optical path design and/or the processing difficulty/cost of the included optical path devices of the present disclosure may also be reduced.
  • the read-write/servo scheme of the present disclosure is mainly developed around the structure of a multi-layer recording medium similar to that shown in Figure 2.
  • This structure requires that the bottom layer of the disk be a servo layer, and that multiple recording layers be prepared on top of the servo layer.
  • the servo layer can be formed by embossing or molding a wobble structure on a substrate, and then sputtering a reflective layer on the wobble structure, and multiple recording layers can be further sequentially sputtered on the servo layer. Formed by shooting or depositing recording media.
  • the multiple recording layers may be structural layers during the disk preparation process, or may be logical layers of the overall structure but performed after data is written. It will be appreciated that the fabrication methods of the disk structures described here are well known in the art, and thus their fabrication methods will not be repeated here.
  • the terms “multiple recording layers”, “multilayer recording medium” or “multilayer” all refer to or include more than 1 recording layer.
  • the present disclosure does not limit the specific number of multiple layers greater than 1, and any multiple layers of recording layers that can use the read-write scheme of the present disclosure are within the scope of the present disclosure.
  • the multilayers of the present disclosure may include multilayers greater than 16 layers.
  • the servo/writing method will not be affected by the change of the number of recording layers.
  • FIG. 4 depicts a block diagram of a read-write system according to an example embodiment of the present disclosure applicable to the above-defined disc structure.
  • the disc to be read and written here can be a multi-layer recording medium with the structure defined above, and the laser read-write module OPU is an execution module for reading and writing to the multi-layer recording medium; the spindle motor drives the disc to rotate ; The servo module controls the motor drive, the torque device and the spindle motor in the OPU, which can ensure that the OPU performs read and write operations at precise positions; the host computer sends read and write instructions to the read and write system.
  • Such a frame structure is known to those skilled in the art, and will not be repeated here.
  • the multilayer recording medium is a multilayer recording medium with the structure defined above, and the multilayer The recording medium may include at least two recording layers.
  • the steps of the method 500 may include: in block 510, writing data on the second recording layer using data writing light, wherein the light incident on the first recording layer on which the data is written is used as a servo for the data writing light.
  • the first recording layer and the second recording layer may be adjacent to each other, and the second recording layer is located on the first recording layer. But this is not a limitation, and in other embodiments, it is also possible that the second recording layer is located above the first recording layer.
  • the advantage of the method 500 is that it can avoid using the light incident on the servo layer as servo light when writing data into the second recording layer, which makes the writing servo on the second recording layer more free.
  • the multi-layer recording medium may also include a servo layer.
  • the servo layer may comprise a wobbled groove track.
  • the method 500 may further include: using the first writing light to write data in the first recording layer, wherein the light incident on the servo layer is used as the servo light of the first writing light.
  • the above-mentioned at least 2 recording layers may be located on the servo layer, and the first recording layer may be adjacent to the servo layer, and the data writing sequence of the plurality of recording layers may be from the Layer-by-layer writing starting from the first recording layer.
  • the plurality of recording layers includes more than 2 recording layers, such as including a third recording layer, a fourth recording layer, a fifth recording layer, etc.
  • the third recording layer may be the same as the second recording layer Adjacent to and located on the second recording layer
  • the fourth recording layer may be adjacent to and located on the third recording layer
  • the fifth recording layer may be adjacent to and located between the fourth recording layer on, and so on, and so on.
  • the writing and/or servo concept of the present disclosure may also be: for writing of the first recording layer, it uses the light incident to the servo layer as servo light, and for any subsequent writing of other recording layers , all of which use the light incident on the previous recording layer with data written adjacent thereto as servo light.
  • the first recording layer is expressed here as using the light incident on the servo layer as the servo light, this does not mean that the first recording layer is closely adjacent to the servo layer. In other embodiments, it is also possible that the first recording layer is at a distance from the servo layer (e.g., with a spacer layer between them), and in addition, it is also possible that the second recording layer is closer to the servo layer than the first recording layer. of.
  • the method 500 may further include: using a third writing light to write data on the third recording layer, wherein the first recording layer on which data is written is incident on The light of the second recording layer is used as the servo light of the third writing light.
  • the method 500 may further include: writing data on the fourth recording layer using a fourth writing light, wherein the fourth recording layer on which data is written is incident on the The light of the three recording layers serves as the servo light of the fourth writing light. And so on, and so on.
  • the recording layer with the first number is closer to the servo layer, the recording layer with the later number is farther away from the servo layer, and the first recording layer is adjacent to the servo layer, and the recording layer with the adjacent number is closer to the servo layer.
  • the recording layers are adjacent to each other. However, this is not necessary, and in some embodiments, recording layers with an earlier number may be farther from the servo layer than recording layers with a lower number.
  • adjacent recording layer does not mean that there must be no interlayers other than recording layers between adjacent recording layers
  • adjacent to the servo layer or “most adjacent to the servo layer” and the like The term does not imply that there must not be an interlayer other than the recording layer from the servo layer.
  • the above-mentioned writing light and the corresponding servo light require the same wavelength, which can help reduce the design difficulty of the objective lens and alleviate the problem of refractive index mismatch.
  • the write light and the servo light may both be blue light with a wavelength of 405 nm.
  • the first recording layer is a recording layer adjacent to the servo layer
  • the data writing sequence of the multiple recording layers is layer-by-layer writing starting from the first recording layer. In this way, writing and servoing of multiple recording layers can be facilitated. In addition, this also means that the writing of multiple recording layers will start from the deepest recording layer of the disc and write layer by layer until it is full.
  • writing data on the first recording layer may include: moving the servo light corresponding to the first writing light along the wobbled groove track.
  • writing data on the recording layer of the next number may include: using the light incident on the recording layer of the previous number adjacent to the data written as the writing process of writing data on the recording layer of the next number. The incoming servo light.
  • the servo light corresponding to the second writing light may be moved along the data track of the first recording layer.
  • the second writing light here may be the data writing light in the embodiment shown in FIG. 5 .
  • FIG. 6 shows a schematic diagram of a writing/servo process for a multi-layer recording medium according to an exemplary embodiment of the present disclosure.
  • the multi-layer recording medium shown in FIG. 6 only shows the L0-L6 layers, wherein the L0 layer is a servo layer, which is for example engraved with a wobble track, compared to the recording layer, the L0 layer is located at the bottom of the disc. Deeper, so it can be defined as the bottom layer of the disc.
  • L1 to L6 are recording layers for data recording, and the recording layer of the next number is located on and adjacent to the recording layer of the previous number. It will be understood that the present disclosure is not limited to the number of layers and that in other embodiments, there may be more or fewer recording layers.
  • the recording layer can be artificially prepared, such as different layers divided by different media, or it can be a logical layer of bulk recording material, which forms the actual data recording after writing data Floor.
  • the servo light when using writing light to write to the first recording layer L1, the servo light can be focused to the servo layer L0; when writing to the second recording layer L2, the servo light can be focused to the layer where the data is written.
  • the first recording layer L1; when writing to the third recording layer L3, the servo light can be focused to the second recording layer L2 where data is written, and so on, writing layer by layer until it is full.
  • FIG. 7 briefly depicts how to use the laser reading and writing module OPU to perform the exemplary reading and writing process of the exemplary embodiment in FIG. 6 .
  • the servo layer L0 is provided with a wobble track structure.
  • a write operation is performed: the servo light is controlled to move along the track of the servo layer by a torquer, so as to ensure that the main beam moves along a fixed track, and data is written until the L1 layer is fully written.
  • OPU inter-layer movement is carried out: the torquer is controlled to move downward, so that the servo light is focused on the data recording layer Ln-1 just written, and at the same time, the compensation mirror is adjusted to focus the main beam on the recording layer Ln.
  • the write operation is performed: the servo light is moved along the data track of the Ln-1 layer, and the servo light feedback signal is used to perform servo control to control the motion posture of the torque device; at the same time, the main beam is used to write data in the Ln layer .
  • a read operation may be performed: instead of using the signal of the servo beam, the signal of the main beam on the detector may be used as a servo control signal, and the data information in the layer may be read at the same time.
  • the servo light is first focused on the L0 layer.
  • the L0 layer can be pre-prepared with, for example, a wobble track. After the servo light is reflected by the wobble track to a detector such as a four-quadrant detector, the signal is calculated and fed back to the control system, and the state of the torque device is adjusted to ensure that the servo light is always focused. Based on the wobble track of the servo layer, and when the disc rotates, the light spot can always move along the track. Then, data can be written into the recording layer of the next number, and the servo light of the recording layer of the next number can be focused on the recording layer of the previous adjacent number at this time.
  • the objective lenses corresponding to the main beam as the read/write light and the auxiliary beam as the servo light can be fixed on the same torque converter, as will be described later with reference to the exemplary read and write optical paths shown in FIGS. 8 to 10 . depicted.
  • the two objective lenses are rigidly connected, and when writing, the movement tracks of the main beam of writing light and the servo light are consistent.
  • the main beam will also move along the same track to ensure that the tracks written by the main beam will not be interleaved/overlapped.
  • the trajectory of the main beam is consistent with that of the auxiliary beam
  • the focal points of the main beam and the auxiliary beam are not on the same layer.
  • the main beam is focused on the L1 layer.
  • a slight deviation of the depth of focus (for example, about 10 ⁇ m) can be adjusted by a compensating mirror on the optical path of the main beam to ensure that the main beam is perfectly focused on the L1 layer. After ensuring that the servo work is complete, you can start writing data to the current layer.
  • the torquer When the driver finishes writing the first recording layer, the torquer will jump the layer to move the focus of the servo light to the L1 layer where the data has just been written. Correspondingly, the main beam is focused to the L2 layer. At this time, the data of the L1 layer will be used as servo information to guide the servo light to move along the data track, so as to ensure that the main beam does not deviate during the writing process.
  • the data writing process of subsequent layers is similar to the previous one.
  • the servo light is focused on the Ln-1 layer to assist the servo, and the main beam is focused on the Ln layer to write data until the entire disc is filled.
  • the above writing/servo scheme can save the process of preparing the reflective layer and the wobble track layer by layer, and reduce the manufacturing cost of the disk. Omitting the part of the reflective layer in the recording layer can increase the transmittance of a single recording layer, thereby increasing the number of recording layers and storage capacity of a single disc. In addition, the writing/serving solution of the present disclosure can also ensure high-speed reading and writing on the basis of increased disc capacity.
  • the main beam as read/write light and the auxiliary beam as servo light may use the same wavelength.
  • a single light source can be used to generate the above-mentioned main and auxiliary beams.
  • the above-mentioned wavelength can be selected as a blue light wavelength of 405nm, which can effectively increase the linear density of storage.
  • the light spot using blue light can be smaller than that of red light.
  • the track width of the servo layer eg, the wobble track, can be narrowed from about 750 nm to 320 nm, which can effectively increase the storage density of a single layer.
  • the first exemplary read-write optical path 100 may at least include a main beam optical path A and a servo beam optical path B.
  • the main beam path A may at least include a laser source 18 , a first beam splitter 13 , a first polarization beam splitter 9 , a first objective lens 3 - 1 and a first detector 12 .
  • the servo beam path B may at least include a laser source 18 , a first beam splitter 13 , a second polarization beam splitter 14 , a second objective lens 3 - 2 and a second detector 21 . That is to say, the optical path A of the main beam and the optical path B of the servo beam can share part of the optical path, which can contribute to a more compact optical path and a lower cost.
  • the main beam path A and the servo beam path B are independent of each other, and it is also possible that there is no shared path between them.
  • laser source 18 The role of the laser source 18 is to generate an initial laser beam.
  • laser source 18 may be, for example, a semiconductor laser.
  • the emission wavelength of the laser source may be, for example, a blue wavelength of 405 nm.
  • the first beam splitter 13 can receive an initial laser beam from a laser source 18 and split it into a main incident beam and a servo incident beam.
  • the main incident beam and the servo incident beam may enter the multi-layer recording medium 1 along the main beam path A and the servo beam path B respectively.
  • the light splitting ratio between the main incident light beam and the servo incident light beam may be determined by the light intensity ratio required for actual writing and servoing.
  • the first beam splitter 13 may be a beam splitting prism.
  • a beam shaping device 15 may be arranged between the laser source 18 and the first beam splitter 13 , which may be used, for example, to collimate and shape the initial laser beam from the laser source 18 .
  • the beam shaping device 15 may be, for example, a combination of a collimating lens 16 and a pair of anamorphic prisms 17 .
  • the collimator lens 16 is configured to be operable to move so that the focal point of the collimator prism coincides with the exit position of the laser light, so as to ensure that the laser light is parallel light after passing through the collimator lens 16 .
  • the angles of the pair of deformed prisms 17 can be operatively adjusted, so that after the laser passes through the pair of deformed prisms 17, the shape of the light spot is adjusted to a circle.
  • the first objective lens 3-1 and the second objective lens 3-2 can be respectively arranged at the position adjacent to the multilayer recording medium 1, and can come from the main incident beam on the main beam optical path A and the servo incident beam from the servo beam optical path B respectively Focusing to different positions of the multilayer recording medium 1 .
  • the first objective lens 3-1 and the second objective lens 3-2 can also respectively collect the main reflected light beam and the servo reflected light beam from different positions of the multilayer recording medium 1, wherein the propagation direction of the main reflected light beam is opposite to the main incident light beam, And the direction of propagation of the servo incident beam is opposite to that of the servo reflected beam.
  • both the main incident beam and the main reflected beam in this paper can be collectively referred to as the main beam, and the main beam can be used as writing light or reading light, while both the servo incident beam and the servo reflected beam can be collectively referred to as Be a servo beam or an auxiliary beam.
  • the above-mentioned first objective lens 3-1 and second objective lens 3-2 can be arranged on the same torquer 2 , and is adapted to move synchronously with the movement of the torque device 2 . In this way, the movement of both the main and auxiliary beams can be conveniently coordinated so that the trajectories of the main and servo beams are kept in alignment.
  • the torquer 2 may be a three-dimensional torquer. Note: During the assembly process, you can first ensure that the focal points of the two objective lenses are roughly at the same horizontal position for assembly.
  • the position deviation of the two objective lenses in the three dimensions of focusing, tracking and tilting can be controlled by the torque device 2 .
  • the position of the objective lens in the vertical direction the depth of the focus in the disk can be controlled to ensure that the focus moves on the data recording layer.
  • the position of the objective lens in the radial direction of the disc it is possible to ensure that the focal point writes data on a predetermined track.
  • the relative angle between the objective lens and the disk it can be ensured that the laser light is incident vertically into the disk.
  • the first polarization beam splitter 9 may be arranged between the first beam splitter 13 and the first objective lens 3-1 for transmitting a main incident beam having a first polarization and reflecting a main reflected beam having a second polarization. Further, the main reflected light beam of the second polarization reflected by the first polarization beam splitter 9 can be guided to the first detector 12, and the first detector 12 can output the focal point indicating the main incident light beam on the multilayer recording medium 1 A first detection of position and/or shape for feedback control of the main beam. In some embodiments, first detector 12 may be a four-quadrant detector.
  • the main reflected light beam with the second polarization reflected from the first polarizing beam splitter 9 can enter the four-quadrant detector through the combination of the collimating mirror 10 and the cylindrical lens 11 .
  • the optical path of the main reflected beam may share some optical devices with the optical path of the main incident beam, such as the first polarizing beam splitter 9 and the objective lens 3-1, but it should be understood that this is not necessary.
  • the second polarization beam splitter 14 may be arranged between the first beam splitter 13 and the second objective lens 3-2 for reflecting the servo incident beam with the first polarization and transmitting the servo reflected beam with the second polarization.
  • the servo reflected beam transmitted via the second polarizing beam splitter 14 may be directed to a second detector 21 which may output a second signal indicative of the focal position and/or shape of the servo incident beam on the multilayer recording medium. The detection results are used for the feedback control of the servo light.
  • the second detector 21 may be a four-quadrant detector.
  • the servo reflected light beam with the second polarization transmitted from the second polarizing beam splitter 14 can be incident to the four-quadrant detector through the combination of the collimating mirror 19 and the cylindrical lens 20 .
  • the optical path of the servo reflected beam may share some optical devices with the optical path of the servo incident beam, such as the second polarization beam splitter 9 and the objective lens 3-2, but it should be understood that this is not necessary.
  • the first polarization and the second polarization may be orthogonal to each other.
  • the main and servo incident light beams with a first polarization may be s-light
  • the main and servo reflected light beams with a second polarization may be p-light.
  • the first 1/4 wave plate 4-1 can be arranged between the first polarization beam splitter 9 and the first objective lens 3-1 to generate the main reflected light beam with the second polarization towards the first polarizing beam splitter 9.
  • the second 1/4 wave plate 4-2 may be arranged between the second polarization beam splitter 14 and the second objective lens 3-2 to generate a servo reflected light beam having the second polarization toward the second polarization beam splitter 11.
  • the first 1/4 wave plate 4-1 and the second 1/4 wave plate 4-2 are shown arranged adjacent to the first objective lens 3-1 and the second objective lens 3-2, respectively. s position.
  • the first 1/4 wave plate 4-1 can be arranged at any position between the first polarizing beam splitter 9 and the first objective lens 3-1
  • the second 1/4 wave plate 4-2 may be arranged at any position between the second polarization beam splitter 14 and the second objective lens 3-2.
  • the laser beam is transmitted through the 1/4 wave plate 4-1, 4-2, it is reflected from the disk and will pass through the 1/4 wave plate 4-1, 4-2 again, in this case,
  • the polarization direction of the laser light passing through the 1/4 wave plate twice will be rotated by 90°, which thereby allows the main reflected beam with the second polarization to be reflected from the first polarizing beam splitter 9, and the servo reflected beam with the second polarization to be reflected from the second polarization beam splitter 9.
  • the two-polarization beam splitter 14 transmits.
  • the read-write optical path 100 may also include a first compensation lens group 30, which may be arranged between the first polarization beam splitter 9 and the first objective lens 3-1, and can be operated to A refractive index mismatch caused by a depth variation of the focal point of the main incident light beam within the multilayer recording medium is compensated.
  • the first compensating lens group 30 may include, for example, a combination of a movable compensating mirror 7 and a fixed lens 6, wherein the compensating mirror 7 may be arranged on a (one-dimensional) stepping motor 8, thereby realizing the operation of the compensating mirror move.
  • the moving direction of the stepper motor 8 may be parallel to the propagation direction of the light, wherein the laser light passes through the center of the compensating mirror 7 . It can be understood that by moving the position of the compensating mirror 7, for example, the problem of refractive index mismatch can be compensated to ensure that the focal spot shape of the disk is close to the diffraction limit, such as meeting the requirement of spot energy RMS ⁇ 0.07 ⁇ .
  • reflecting mirrors 5-1 and 5-2 can be further arranged after the first polarizing beam splitter 9 and the second polarizing beam splitting mirror 11 respectively, so as to change the propagation direction of the light beam, for example, change the light beam from the original level The direction is changed to a vertical direction for easier incidence to multi-layer recording media.
  • the laser beam with the first polarization is emitted from the laser source 18, and the laser beam forms a main incident beam and a servo incident beam with the first polarization after being split by the first beam splitter 13, and the main incident beam is transmitted through the first polarization splitting Mirror 9, the first compensating lens group 30, the first 1/4 wave plate, incident to the first position (for example, the position on the first recording layer L1) of the multilayer recording medium 1 via the first objective lens 3-1, the second An objective lens 3-1 collects the reflected light from the first position to form the main reflected light beam, and the main reflected light beam passes through the first 1/4 wave plate 4-1 and the first compensating lens group 30 in reverse again and enters the first polarization Beamsplitter9.
  • the main reflected beam may have a second polarization direction orthogonal to the first polarization direction.
  • the first polarization beam splitter 9 reflects the main reflected beam with the second polarization to the first detector 12 .
  • the servo incident beam is incident from the first beam splitter 13 to the second polarization beam splitter 14, which may be designed to reflect the servo incident beam having the first polarization.
  • the servo incident light beam reflected by the second polarization beam splitter 14 passes through the second 1/4 wave plate 4-2, and is incident on the second position of the multilayer recording medium 1 (for example, on the servo layer L0) via the second objective lens 3-2.
  • the second objective lens 3-2 collects the reflected light from the second position to form a servo reflected light beam, and the servo reflected light beam passes through the second 1/4 wave plate 4-2 in reverse again, and enters the second polarization beam splitter 14. Since the beam passes through the second 1/4 wave plate 4-2 twice, the servo reflected beam can have a second polarization direction orthogonal to the first polarization direction.
  • the second polarization beam splitter 14 transmits the servo reflection beam with the second polarization to the second detector 21 .
  • the signal of the second detector 21 can be used to control the focus, tracking and angular tilt of the torquer 2 .
  • the first detector 12 such as a four-quadrant detector can adjust the first compensating lens group 30 (for example, through a one-dimensional step
  • the motor 8 adjusts the position of the movable compensating mirror 7 in the first compensating lens group 30), so that the focus of the main incident light beam is focused on the recording layer Ln, and the problem of refractive index mismatch is corrected.
  • torquer 2 When writing starts, torquer 2 will keep the focus of the servo beam moving along the wobble track or data track on the Ln-1 layer. Since the two objective lenses 3-1 and 3-2 are rigidly fixed on the torquer, the focus of the main beam will also move along a fixed track, ensuring that the written data will not experience track crosstalk.
  • the second detector 21 can no longer work, and only the signal obtained by the first detector 12 can be used to control the torquer 2 to perform focus, tracking and tilt servos.
  • the stepping motor 8 is controlled to adjust the first compensating lens group 30 to complete the compensation of the refractive index mismatch.
  • Fig. 9 shows a second exemplary read-write optical path 200, which differs from the first exemplary read-write optical path 100 in Fig. 8 in that: an energy feedback system for a laser source is added to the second exemplary read-write optical path 200 40.
  • the energy feedback system 40 may at least include a second beam splitter 22 and a third detector 24, wherein the second beam splitter 22 is arranged between the first beam splitter 13 and the first polarizing beam splitter 9 , for splitting part of the light from the main incident beam from the first beam splitter 13 and directing it to the third detector 24 .
  • the third detector 16 receives and detects part of the light split from the second beam splitter 22, and outputs a third detection result indicating the laser intensity of the initial laser beam, which can be used as a feedback result to control the laser source 18 to Keep the intensity of the emitted laser light stable.
  • the third detector 16 may be a light intensity detector.
  • the lens 15 can also be arranged between the second beam splitter 22 and the third detector 24 to achieve convergence of the light spot, thereby facilitating the light intensity detection of the third detector 24 .
  • the exemplary read and write optical paths of FIGS. 8 and 9 may be particularly applicable to multilayer recording media that are prepared and written layer by layer (ie, layer preparation and writing are not separated). This is because when writing, each writing light can be focused on the uppermost Ln layer, and the distance from the adjacent recording layer Ln-1 for servo to the above-mentioned uppermost layer can be kept constant. Therefore, servo light may not need to overcome the refractive index mismatch problem.
  • the perfect focus of the objective lens can also be engineered on the subsurface data layer.
  • the position of the compensating mirror 7 can be adjusted to ensure that the perfect focus of the main beam falls on the surface of the disk.
  • FIG. 10 shows a third exemplary read/write optical path 300 , which differs from the second exemplary read/write optical path 200 in FIG. 9 in that a second compensating lens group 50 for the servo beam is newly added.
  • the second compensation lens group 50 may include a movable compensation mirror 22 and a fixed mirror 24, wherein the compensation mirror 22 is arranged between the second polarization beam splitter 14 and the second objective lens 3-2 so as to be operatively A refractive index mismatch caused by a depth variation of the focus of the servo incident beam within the multilayer recording medium is compensated.
  • the movable compensating mirror 22 may be arranged on a (eg, one-dimensional) stepping motor 23 , and the movement of the movable compensating mirror 22 may be controlled by operating the stepping motor 23 . Similar to the stepping motor 8, the moving direction of the stepping motor 23 can be parallel to the propagation direction of light.
  • the control of the stepping motor 23 can be jointly determined by the signal of the second detector 21 and the voltage applied in the focus servo direction of the torque device 2 .
  • both the main beam and the servo beam each have a compensating lens group, which allows the two beams to correct or compensate for the aberration problems that occur during the reading and writing process, thereby correcting the refractive index aberration.
  • the example read and write optical path of FIG. 10 has good adaptability to multi-layer recording media with various structures, and it can especially be suitable for layer-by-layer data writing and discs that are not separated during the disc manufacturing process. , or adapted to pre-prepared discs with separate writing and disc making processes.
  • the read-write device of the present disclosure may not be limited to the above-mentioned exemplary read-write optical paths, but may cover a wider range of read-write devices that can implement the above-mentioned data writing/servo method of the present disclosure.
  • the read-write device may include: a servo optical path assembly, which is used to irradiate servo incident light to the first recording layer on which data is written in the multi-layer recording medium, and receive Reflected servo reflection light, wherein the multiple recording medium includes at least said first recording layer and a second recording layer; a main optical path assembly for irradiating data writing light to said second recording layer; and a control device, which may It is configured to use the servo reflected light as servo light, and control the data writing light to write data into the second recording layer.
  • the above-mentioned main optical path assembly can also be used to irradiate the first writing light to the first recording layer; the above-mentioned servo optical path assembly can also irradiate another servo incident light to the servo layer of the multi-layer recording medium, And receive another servo reflection light reflected by the servo layer; and the control device may also use the other servo reflection light as the servo light to control the first writing light to write data into the first recording layer.
  • the servo optical path assembly may include, for example, a servo beam optical path as shown in FIGS. 21.
  • the main optical path assembly may at least include the main beam optical path and related devices as shown in Figures 8 to 10, and the related devices may at least include, for example, the first objective lens 3-1, the first polarizing beam splitter 9, and the first 1/4 wave plate 4-1.
  • the first compensation lens group 30 can be realized by one or more of the digital servo algorithm implementation module, the precision mechanical platform module, the analog front-end driver module, and the host PC control module in FIG. 4 .
  • the objective lens and torquer can be designed so that when the torquer is static, the focal point of the objective lens is at the center of the writable area of the disc.
  • the focal point of the objective lens can be designed so that the focal point of the objective lens is 300 ⁇ m away from the surface without applying current to the torquer.
  • the write/servo scheme can save the process of preparing reflective layer and wobble track layer by layer, reducing the cost of disk preparation. Omitting the part of the reflective layer in the recording layer can increase the transmittance of a single recording layer, thereby increasing the number of recording layers and storage capacity of a single disc. In addition, the writing/serving solution of the present disclosure can also ensure high-speed reading and writing on the basis of increased disk capacity.
  • the servo light used in this disclosure can also be blue light with a wavelength of 405nm.
  • the focused Airy disk is smaller, which helps to improve the surface density of the disc.
  • the storage capacity of a single disc can be increased.
  • the torque device clamping the double objective lens ensures the rigid connection of the two objective lenses, and can meet the requirements of high-speed response of the driver.
  • the read-write optical path of the present disclosure can compensate possible aberrations that may occur during focusing and layer selection, thereby overcoming the problem of refractive index mismatch.
  • the servo scheme and optical path of the present disclosure can support more layers of optical discs for read and write operations. In addition to reading and writing discs prepared layer by layer, it is also possible to read and write block materials without prepared read-write layers.
  • the disk manufacturing method will reduce the preparation cost of the disk, and the reading and writing optical path and the servo scheme can ensure high-speed reading and writing of the disk.

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Abstract

本公开的各实施例提供了一种多层记录介质的数据写入方法及其读写装置，其中多层记录介质至少包括第一记录层和第二记录层。该方法包括：使用数据写入光在所述第二记录层写入数据，其中以入射到写有数据的所述第一记录层的光作为所述数据写入光的伺服光。本公开的数据写入方法提供了利用入射到之前的写有数据的记录层的光作为伺服光的构思，这有助于简化伺服方案，可以实现对具有更多存储层的记录介质的快速读写。

Description

多层记录介质的数据写入方法及其读写装置
本申请要求提交于2021年6月11日的名称为“多层记录介质的数据写入方法及其读写装置”的在先中国申请号202110653929.4的优先权，该在先中国申请以全文引用的方式并入本文。
技术领域
本公开的各实施例涉及光存储领域，更具体地涉及一种多层记录介质的数据写入方法及其读写装置。
背景技术
信息时代的来临导致数据存储的压力骤增。根据国际数据公司IDC预测，到2025年，全球的数据将达到175ZB。但是其中大量数据无法得到长期保存，比如公共场所的监控视频一般只保存3个月，随后即会被删除、覆盖。造成该现象的主要原因是存储设备的价格较为高昂。
现有的存储技术，诸如固态硬盘、硬盘等无法长时间保存数据(>5年)；磁带的保存时间可达到20年，但是它对保存环境要求较高。温度、湿度和电磁干扰等都会影响磁带的存储寿命。蓝光等光存储介质虽然可以廉价地长时间保存数据，但是其存储密度无法满足大量数据的存储需求。
目前光存储提升存储容量的发展趋势为多层存储。多层存储虽然能有效提高存储密度，但是多层的结构使读写操作，伺服控制的难度增大。
发明内容
本公开的目的在于提供了一种改进的多层记录介质的数据写入方法及其读写装置，其可以有助于增加单张盘片的记录层数和存储容量。此外，本公开的写入/伺服方案还可以保证在盘片容量提升的基础上依然能够高速读写。
根据本公开的第一方面，提供了一种多层记录介质的数据写入方法。该多层记 录介质至少包括第一记录层和第二记录层，该方法包括：使用数据写入光在所述第二记录层写入数据，其中以入射到写有数据的所述第一记录层的光作为所述数据写入光的伺服光。
因此，本公开的数据写入方法提供了利用入射到之前的写有数据的记录层的光作为伺服光的构思，这有助于简化伺服方案，并且使得盘片的伺服更加自由。由于可将入射到记录层的光作为向另一记录层写入数据的伺服光，因此，即使记录介质的存储层数增加，依然能够实现高速读写，有助于增加单张盘片的记录层数和存储容量。
在一些实施例中，所述多层记录介质还包括伺服层，所述方法还包括：使用第一写入光在所述第一记录层写入数据，其中以入射到所述伺服层的光作为所述第一写入光的伺服光。
在一些实施例中，所述第一记录层和所述第二记录层彼此相邻，并且所述第二记录层位于所述第一记录层之上。
在一些实施例中，所述数据写入光以及其对应的伺服光波长相同。
在一些实施例中，所述第一记录层为与所述伺服层邻接的记录层，所述多个记录层的数据写入顺序为从所述第一记录层开始的逐层写入。
在一些实施例中，在写入过程中，所述伺服光和对应的所述数据写入光的运动轨迹保持一致。
在一些实施例中，所述伺服层包括摆动沟槽轨道，所述使用第一写入光在所述第一记录层上写入数据包括：控制所述第一写入光对应的伺服光沿所述摆动沟槽轨道运动。
在一些实施例中，所述使用所述数据写入光在所述第二记录层上写入数据包括：控制所述数据写入光对应的伺服光沿所述第一记录层的数据轨道移动。
在一些实施例中，所述波长均为405nm。
根据本公开的第二方面，提供了一种读写装置。该读写装置包括：伺服光路组件，用于向多层记录介质中写有数据的第一记录层照射伺服入射光，并且接收经由所述第一记录层反射的伺服反射光，其中，所述多次记录介质至少包括所述第一记录层和第二记录层；主光路组件，用于向所述第二记录层照射数据写入光；以及控制装置，用于以所述伺服反射光作为伺服光，控制所述数据写入光以向所述第二记录层写入数据。
在一些实施例中，所述控制装置还用于在写入过程中控制所述数据写入光和对应的所述伺服光两者的运动轨迹保持一致。
在一些实施例中，所述主光路组件还用于向所述第一记录层照射第一写入光，所述伺服光路组件还用于向所述多层记录介质的伺服层照射另一伺服入射光，并且接收经由所述伺服层反射的另一伺服反射光；所述控制装置还用于以所述另一伺服反射光作为伺服光，控制所述第一写入光以向所述第一纪录层写入数据。
在一些实施例中，所述主光路组件包括第一物镜，所述第一物镜适于将所述数据写入光聚焦至所述多层记录介质上的第二记录层；所述伺服光路组件包括第二物镜，所述第二物镜适于将所述伺服入射光束聚焦至所述多层记录介质上的第一记录层。
在一些实施例中，其中所述第一物镜和所述第二物镜被设置在同一力矩器上，并且两者适于随同所述力矩器的移动而同步移动。
在一些实施例中，该读写装置还包括：激光源，用于发射初始激光束；第一分束器，用于将所述初始激光束分为主入射光束和伺服入射光束；第一偏振分光镜，位于所述第一分束器和所述第一物镜之间，用于透射具有第一偏振的所述主入射光束，所述主入射光束作为所述数据写入光。
在一些实施例中，该读写装置还包括：第一补偿透镜组，位于所述第一偏振分光镜和所述第一物镜之间，并且能够被操作地以补偿所述主入射光束的焦点在所述多层记录介质内的深度变化所导致的折射率失配。
根据本公开的第三方面，提供了一种用于多层记录介质的读写装置。该读写装置包括：激光源，用于发射初始激光束；第一分束器，用于将所述初始激光束分为主入射光束和伺服入射光束；第一物镜，用于将所述主入射光束聚焦至所述多层记录介质上的第一位置；以及第二物镜，用于将所述伺服入射光束聚焦至所述多层记录介质上的第二位置，并且收集来自所述第二位置的伺服反射光束，所述第二位置不同于所述第一位置；其中所述第一物镜和所述第二物镜被设置在同一力矩器上，并且两者适于随同所述力矩器的移动而同步移动。
在一些实施例中，该读写装置还包括:第一偏振分光镜，位于所述第一分束器和所述第一物镜之间，用于透射具有第一偏振的所述主入射光束，并且反射具有第二偏振的所述主反射光束。
在一些实施例中，该读写装置还包括:第二偏振分光镜，位于所述第一分束器和所述第二物镜之间，用于反射具有第一偏振的所述伺服入射光束，并且透射具有第二偏振的所述伺服反射光束。
在一些实施例中，该读写装置还包括：第一补偿透镜组，位于所述第一偏振分光镜和所述第一物镜之间，并且能够被操作地以补偿所述主入射光束的焦点在所述多层记录介质内的深度变化所导致的折射率失配。
在一些实施例中，该读写装置还包括：第一探测器，用于接收从第一偏振分光镜反射的所述主反射光束，并且输出指示所述主入射光束在所述多层记录介质上的焦点位置和/或形状的第一探测结果。
在一些实施例中，该读写装置还包括：第二探测器，被布置成接收从所述第二偏振分光镜透射的所述伺服反射光束，并且输出指示所述伺服入射光束在所述多层记录介质上的焦点位置和/或形状的第二探测结果。
在一些实施例中，该读写装置还包括：第一1/4波片，位于所述第一偏振分光镜和所述第一物镜之间，以产生朝向所述第一偏振分光镜的具有第二偏振的所述主反射光束。
在一些实施例中，该读写装置还包括：第二1/4波片，位于所述第二偏振分光镜和所述第二物镜之间，以产生朝向所述第二偏振分光镜的具有第二偏振的所述伺服反射光束。
在一些实施例中，该读写装置还包括：第二分束器，位于所述第一分束器和所述第一偏振分光镜之间，用于从来自所述第一分束器的所述主入射光束中分出部分光；以及第三探测器，用于对来自所述第二分束器的所述部分光进行检测，并且输出指示所述初始激光束的激光强度的光强探测结果。
在一些实施例中，该读写装置还包括：第二补偿透镜组，位于所述第二偏振分光镜和所述第二物镜之间，并且能够被操作地以补偿所述伺服入射光束的焦点在所述多层记录介质内的深度变化所导致的折射率失配。
还应当理解，发明内容部分中所描述的内容并非旨在限定本公开的实施例的关键或重要特征，亦非用于限制本公开的范围。本公开实施例的其它特征将通过以下的描述变得容易理解。
附图说明
结合附图并参考以下详细说明，本公开各实施例的上述和其他特征、优点及方面将变得更加明显。在附图中，相同或相似的附图标记表示相同或相似的元素，其中：
图1示出了一种示例性多层记录介质的结构示意图。
图2示出了另一示例性多层记录介质的结构示意图。
图3示出用于图2所示的多层记录介质的示例性读写光路装置。
图4示出了根据本公开的示例实施例的用于多层记录介质的读写系统框架图。
图5展示了根据本公开的示例实施例的体现了多层记录介质的写入以及伺服构思的方法流程示意图。
图6展示了根据本公开的示例实施例的用于多层记录介质的写入/伺服过程示意图。
图7简要地描绘了如何利用激光读写模块OPU进行图6的示例实施例的示例性读写流程。
图8示出了根据本公开的示例实施例的用于多层记录介质的第一示例性读写光路的示意图。
图9示出了根据本公开的示例实施例的用于多层记录介质的第二示例性读写光路的示意图。
图10示出了根据本公开的示例实施例的用于多层记录介质的第三示例性读写光路的示意图。
具体实施方式
下面将参照附图更详细地描述本公开的实施例。虽然附图中显示了本公开的某些实施例，然而应当理解的是，本公开可以通过各种形式来实现，而且不应该被解释为限于这里阐述的实施例，相反提供这些实施例是为了更加透彻和完整地理解本公开。应当理解的是，本公开的附图及实施例仅用于示例性作用，并非用于限制本公开的保护范围。
下面将首先参照图1至图4来介绍常规的多层记录介质的示意结构及其读写光路，以便提供对现有方案的了解。这里需要注意的是，这些介绍并不意味着承认或默认所介绍的现有方案为本领域的现有技术。
图1示出了一种示例性多层记录介质的结构图。如图1所示，诸如光盘的示例多层记录介质可以包括具有摆动(wobble)结构的两层记录层，每一层又包括多种介质层。该多层介质层例如可以包括诸如GeSbTe的相变材料层和诸如ZnS-SiO2的反射层。当激光照射至相变材料层后，该相变材料层可以从晶态转换为非晶态，其伴随折射率的变化，由此记录数据。诸如ZnS-SiO2的反射层同样会反射信号，该反射信号携带的信息可以包括摆动结构中所调制的地址，时钟等信息。
对于图1所示的结构，可以使用辅助驱动器来完成循迹伺服，但是每一个记录层中的诸如ZnS-SiO2的反射层都会反射一部分激光的能量。如果要增加存储容量，可以增加记录层的数量。然而，越底层的记录层所反射回探测器的能量会越低，这导致了限制了记录层数目的增加。
为了更进一步地增加记录层的数量以便增加存储容量，已提出了如图2所示的另外结构的记录存储介质。如图2所示，盘片中只有最底层有摆动结构，其余的多层(例如，多达16层)都为数据层，用以记录数据。这些记录层中不需要逐层制备摆动结构的凹凸结构，这简化了盘片的制备工艺。在一些实施例中，记录层A和B的反射率分别只有0.7％和1.5％，这使得能够将记录层的层数从蓝光记录介质的4层增加到多达例如16层，这大大增加了单盘的存储容量。
图3是实现图2所示的多层光盘结构的示例性读写光路。其中，可以使用诸如405nm蓝光波长的激光器LD1出射的激光为写入光。可以使用光电二极管1所获得的信号作为反馈信号来控制力矩器沿着z轴运动，完成选层、聚焦、伺服等任务。在写入过程中，循迹伺服可以由诸如655nm红光波长的激光器LD2出射的红光来完成。通过调整调节透镜RL2的位置，可以保证红光的焦点一直维持在盘片的摆动结构层，从而不会因为力矩器的上下移动而导致红光的焦点发生变化。读取过程中，诸如655nm波长的激光器LD1可以不工作，循迹伺服的信号可以由写入的数据作为信号反馈源，来控制力矩器在盘片径向上的伺服，从而读出数据。
由于图3的读写光路需要同时使用诸如405nm和655nm的两种不同波长的光，这导致在设计物镜时，只能针对一种波长(例如，红光波长)来实现完美聚焦。而对于另一波长而言，可能会选层时出现折射率失配问题。譬如，当使用作为写入光的蓝光聚焦到不同层进行读写时，蓝光焦点可能在盘片的不同深度进行变化，此时物镜可能无法针对盘片中的任何深度处的蓝光焦点进行完美聚焦，这导致聚焦光斑变大，z 轴方向拉伸，光斑的能量密度降低。这就是折射率失配问题。为了解决这一问题，图3的读写光路通过调整调节透镜RL1的位置，来补偿由于焦点深度发生变化所引起的折射率失配。
尽管图3的读写光路仍然能够依据读写伺服原理来保证对多层记录介质的读写操作的可行性，但图3的读写光路仍有存在以下不足。
1.为区分伺服光和写入光，图3的方案需要使用红光作为伺服光，蓝光作为写入光。然而，红光的爱里斑大于蓝光，相应地，只能选用DVD标准的摆动轨道作为伺服层。相较于蓝光标准，DVD的轨道间距更大，因此，面密度将会下降，从而降低存储容量。
2.伺服光和写入光的波长不同，这导致单片物镜无法对色差进行补偿。尽管可以通过调节RL1的位置，来补偿色差以及折射率失配的问题，但是对补偿镜RL1和物镜的设计和加工要求较高，这增加了图3的读写光路生产难度和成本。
3.由于上述的缺陷，图3的读写光路难以对16层以上的记录层的盘片进行读写，因此，图3的设计方案具有局限性，无法支持更多记录层的伺服读写。
为此，本公开的目的在于提供一种改进的多层记录介质的读写/伺服方案和相应的光路，其不仅可以有效地支持单盘的存储容量的增加，而且还能够支持多层记录介质(甚至超过16层的记录介质)的高速读写。此外，本公开的光路设计的难度和/或所包含的光路器件的加工难度/成本也可以有所降低。
这里首先需要说明的是，本公开的读写/伺服方案主要围绕与图2类似的多层记录介质的结构来展开，该结构即要求：盘片的底层为伺服层，而多个记录层制备在伺服层之上。仅作为示例，伺服层例如可以通过在基板上压印或模塑形成摆动(wobble)结构，而后在摆动结构上溅射反射层来形成，多个记录层则可以通过在伺服层上进一步依次溅射或沉积记录介质来形成。在本公开的实施例中，多个记录层可以是盘片制备过程中的结构分层，也可以是整体结构、但在写入数据后进行的逻辑分层。将会理解，这里描述的盘片结构的制备方式是本领域所公知的，因此它们的制备方式这里不再赘述。
如本公开所使用的，术语“多个记录层”、“多层记录介质”或“多层”均指代或包括大于1层的记录层。本公开并不限制大于1层的多层的具体数量，任何可以使用本公开的读写方案的记录层的多层都在本公开的范围之内。在一些实施例中，本公 开的多层可以包括大于16层的多层。另外，通过后面的描述，还将会理解，在本公开中，不会因为记录层数的变化而影响伺服/写入方式。
下面将参照上面限定的盘片结构来描述本公开的基于多层记录介质的读写/伺服方案以及相关光路的实现。
图4描绘了适用于上述限定的盘片结构的根据本公开的示例实施例的读写系统框架图。如图4所示，这里要读写的盘片可以为上面所限定结构的多层记录介质，激光读写模块OPU为对多层记录介质进行读写的执行模块；主轴电机带动盘片进行旋转；伺服模块控制电机驱动，OPU内的力矩器以及主轴电机，可以保证OPU在精确的位置执行读写操作；上位机对读写系统发出读写指令。这样的框架结构为本领域技术人员已知，这里不再赘述。
图5展示了根据本公开的示例实施例的体现了多层记录介质的写入和/或伺服构思的方法示意图，其中多层记录介质即为上面所限定结构的多层记录介质，该多层纪录介质可以至少包括2层记录层。
该方法500的步骤可以包括：在框510中，使用数据写入光在第二记录层上写入数据，其中以入射到写有数据的第一纪录层的光作为上述数据写入光的伺服光。在一些实施例中，第一记录层和第二记录层可以彼此相邻，并且所述第二记录层位于所述第一记录层之上。但这并非限制，在其他实施例中，第二纪录层位于第一纪录层之上也是可能的。该方法500的有益之处在于可以在对第二记录层进行数据写入时，避免使用入射至伺服层的光作为伺服光，这使得对第二记录层的写入的伺服变得更加自由。
在进一步的实施例中，多层记录介质还可以包括伺服层。仅作为示例，伺服层可以包括摆动沟槽轨道。该方法500还可以进一步包括：使用第一写入光在所述第一记录层写入数据，其中以入射到伺服层的光作为所述第一写入光的伺服光。在这些实施例中，前面提及的至少2层纪录层可以位于伺服层之上，并且第一记录层可以与所述伺服层邻接，该多个记录层的数据写入顺序可以为从所述第一记录层开始的逐层写入。
在多个记录层包括大于2个的记录层——譬如包括第三记录层、第四记录层、第五记录层等——的实施例中，其中第三记录层可以与第二记录层相邻且位于第二记录层之上，第四记录层可以与第三记录层相邻且位于第三记录层之上，第五记录层可 以与第四记录层相邻且位于第四记录层之上，等等，依此类推。
更进一步地，本公开的写入和/或伺服构思还可以在于:针对第一记录层的写入，其使用入射至伺服层的光作为伺服光，而对于任何后续的其他记录层的写入，其均以入射至与其相邻的写有数据的前一记录层的光作为伺服光。
这里需要注意的是：尽管这里第一记录层被表述为以入射至伺服层的光作为伺服光，但这并不意味着第一记录层与伺服层紧密相邻。在其他实施例中，第一记录层与伺服层相隔一定距离(例如它们之间相隔有隔离层)也是可能的，以及另外，第二记录层相比第一记录层更为邻近伺服层也是可能的。
在多个记录层还包括第三记录层的实施例中，方法500还可以进一步包括：使用第三写入光在第三记录层上写入数据，其中以入射到写有数据的所述第二记录层的光作为所述第三写入光的伺服光。在多个记录层还包括第四记录层的实施例中，方法500还可以进一步包括：使用第四写入光在第四记录层上写入数据，其中以入射到写有数据的所述第三记录层的光作为所述第四写入光的伺服光。等等，以此类推。
这里需要注意的是：通常而言，编号靠前的记录层更为靠近伺服层，编号靠后的记录层更为远离伺服层，以及第一记录层与伺服层相邻，且相邻编号的记录层之间是相邻的。但这都不是必须的，在一些实施例中，编号靠前的记录层也可能比编号靠后的记录层更为远离伺服层。另外，术语“相邻记录层”或类似术语并不意味着相邻记录层之间必定不存在非记录层的隔层，以及术语“与伺服层相邻”或“最为邻近伺服层”等类似术语并不意味着与伺服层之间必定不存在非记录层的隔层。
在一些实施例中，上述写入光和对应的伺服光要求波长彼此相同，这可以有助于降低物镜的设计难度以及缓解折射率失配的问题。仅作为示例，写入光和伺服光可以均为波长为405nm的蓝光。
在又一些实施例中，第一记录层为邻接所述伺服层的记录层，所述多个记录层的数据写入顺序为从所述第一记录层开始的逐层写入。以这种方式，可以方便多个记录层的写入和伺服。此外，这还表明多个记录层的写入将从盘片最深的记录层开始逐层写入，直至写满为止。
为了实现对记录层的数据写入，在本公开的实施例中，其要求伺服光和对应的写入光的运动轨迹保持一致。更进一步地，在伺服层包括摆动沟槽轨道的实施例中，在第一记录层上写入数据可以包括：使第一写入光对应的伺服光沿摆动沟槽轨道移 动。更进一步地，在后一编号的记录层上写入数据可以包括：可以以入射至写有数据的相邻的前一编号记录层的光作为在该后一编号记录层上写入数据的写入光的伺服光。例如，在使用第二写入光在第二记录层上写入数据时，可以使所述二写入光对应的伺服光沿所述第一记录层的数据轨道移动。注：为了方便描述起见，这里的第二写入光可以为图5所示的实施例中的数据写入光。
为了更加直观地理解本公开的用于多层记录介质的写入和伺服过程，图6展示了根据本公开的示例实施例的用于多层记录介质的写入/伺服过程示意图。
为了简便起见，图6所示的多层记录介质仅仅示出了L0-L6层，其中L0层为伺服层，其例如刻有摆动轨道，相较于记录层而言，L0层处于盘片的更深层，因此其可以被定义为盘片的底层。L1到L6为用于数据记录的记录层，后一编号的记录层位于前一编号的记录层之上并且与之相邻。将会理解，本公开不对层数作限制，在其他实施例中，可以有更多或更少的记录层。另外，如前所述的，记录层可以是人工制备的，例如由不同介质分割的不同分层，也可以是块状记录材料的逻辑分层，其在写入数据后才形成实际的数据记录层。如图6所示，当使用写入光针对第一记录层L1写入时，伺服光可以聚焦至伺服层L0；当针对第二记录层L2写入时，伺服光可以聚焦至写有数据的第一记录层L1；当针对第三记录层L3写入时，伺服光可以聚焦至写有数据的第二记录层L2，依此类推，逐层写入，直至写满为止。
图7简要地描绘了如何利用激光读写模块OPU进行图6的示例实施例的示例性读写流程。
首先，在框710，进行OPU定位：控制力矩器移动物镜，使伺服光聚焦到伺服层L0，同时调节补偿镜，使主光束聚焦到数据记录层L1。在一些实施例中，伺服层L0设置有摆动轨道结构。
然后，在框720，执行写操作：通过力矩器控制伺服光沿着伺服层的轨道运动，以保证主光束沿着固定轨道移动，并写入数据，直至将L1层写满。
在框730，进行OPU层间移动：控制力矩器向下移动，使伺服光聚焦到刚写入的数据记录层Ln-1，同时，调节补偿镜，使主光束聚焦到记录层Ln。
在框740，执行写操作：使伺服光沿着Ln-1层的数据轨道移动，利用伺服光反馈的信号进行伺服控制，控制力矩器的运动姿态；同时，使得主光束在Ln层写入数据。
在框750，判断盘片是否写满。如果未写满，则可以返回至框730，以继续在下一记录层的写入。
在框760，可以执行读操作：此时可以不使用伺服光束的信号，而使用主光束在探测器上的信号来作为伺服控制信号，同时读取层内的数据信息。
从上面的图6和图7的描述可知，其展现了逐层写入的一个示例实施例，其要求每次都需要将当层写满才能写入下一层。例如，对一张全新的盘片进行写入时，伺服光首先聚焦于L0层。L0层可以预先制备有例如摆动轨道，伺服光被摆动轨道反射到诸如四象限探测器的探测器后，信号经过计算反馈到控制系统后，对力矩器的状态进行调整，以保证伺服光一直聚焦于伺服层的摆动轨道，并且在盘片转动时，光斑可以始终沿着轨道运动。接着，可以进行后一编号的记录层的数据写入，后一编号的记录层的伺服光此时可以聚焦到前一相邻编号的记录层上。
在一些实施例中，作为读/写光的主光束和作为伺服光的辅助光束所对应的物镜可以被固定在同一力矩器上，如后面参照图8至图10所示的示例读写光路所描绘的。此时，两个物镜为刚性连接，在写入时，作为写入光的主光束和伺服光的运动轨迹是一致的。当伺服光沿着摆动轨道移动时，主光束也会沿着相同轨迹移动，以保证主光束写入数据的轨迹不会发生交错/重叠。
虽然主光束的运动轨迹和辅助光束保持一致，但是主光束和辅助光束的焦点不在同一层。例如，当伺服光聚焦于L0层时，主光束聚焦于L1层。焦点深度的略微偏差(例如，约10μm)可以由主光束光路上的补偿镜进行调整，以保证主光束完美聚焦于L1层。在保证伺服工作完备后即可开始对当层进行数据写入。
当驱动器完成第一记录层的写入后，力矩器将会跳层操作，将伺服光的焦点移动到刚写入数据的L1层。相对应的，主光束聚焦到L2层。此时L1层的数据将作为伺服信息，指引伺服光沿着数据轨道移动，保证主光束在写入过程中不发生偏移。后续层的数据写入过程和前面类似，伺服光聚焦于Ln-1层辅助伺服，主光束聚焦于Ln层进行数据写入，直至将整张光盘写满。
将会理解，上述写入/伺服方案可以省去逐层制备反射层和摆动轨道等工艺，降低盘片的制备成本。记录层中略去反射层这一部分可以提升单记录层的透射率，进而增加单张盘片的记录层数和存储容量。此外，本公开的写入/伺服方案还可以保证在盘片容量提升的基础上依然能够高速读写。
另外，在本公开的读写和伺服方案下，作为读/写光的主光束和作为伺服光的辅助光束可以采用相同的波长。这意味着可以采用单光源来产生上述主光束和辅助光束。作为示例，上述波长可以选择405nm的蓝光波长，这可以有效提高地存储的线密度。与图2使用红光作为伺服光的方案相比，使用蓝光的光斑可以小于红光的光斑。在这种情况下，可以将伺服层的例如摆动轨道的轨道宽度从约750nm缩小为320nm，这可以有效地提高单层的存储密度。
下面将参照图8至图10来描述可以实现上述图5至图7的读写操作的读写光路的不同示例实施例。
如图8所示，其示出了针对多层记录介质1的第一示例性读写光路100,该第一示例性读写光路100可以至少包括主光束光路A和伺服光束光路B。
在一些实施例中，主光束光路A可以至少包括激光源18、第一分束器13、第一偏振分光镜9、第一物镜3-1和第一探测器12。伺服光束光路B可以至少包括激光源18、第一分束器13、第二偏振分光镜14、第二物镜3-2和第二探测器21。也就是说，主光束光路A和伺服光束光路B可以共享部分光路，这可以有助于光路更加紧凑且成本更低。然而，将会理解，在其他实施例中，主光束光路A和伺服光束光路B彼此独立，它们之间没有任何的共享光路也是可能的。
激光源18的作用在于产生初始激光束。在一些实施例中，激光源18例如可以为半导体激光器。在又一些实施例中，激光源的发射波长可以为例如405nm的蓝光波长。
第一分束器13可以接收来自激光源18的初始激光束，并将其分为主入射光束和伺服入射光束。该主入射光束和伺服入射光束可以分别沿主光束光路A和伺服光束光路B入射至多层记录介质1。在一些实施例中，主入射光束和伺服入射光束之间的分光比可以由实际写入和伺服所需要的光强比决定。在一些实施例中，第一分束器13可以为分束棱镜。
在一些实施例中，可以在激光源18和第一分束器13之间设置光束整形器件15，其可以例如用于对来自激光源18的初始激光束进行准直、光斑整形。仅作为示例，光束整形器件15例如可以为准直透镜16和变型棱镜对17的组合。譬如，准直透镜16被设置成可被操作地移动以使得准直棱镜的焦点与激光的出射位置重合，从而保证激光在经过准直透镜16后为平行光。变型棱镜对17的角度则可被操作地调整，以 使得激光在经过变形棱镜对17后，光斑的形状调整为圆形。
第一物镜3-1和第二物镜3-2可以分别被设置在邻近多层记录介质1的位置，并且可以将来自主光束光路A的主入射光束和来自伺服光束光路B上的伺服入射光束分别聚焦至多层记录介质1的不同位置。同时，第一物镜3-1和第二物镜3-2还可以分别收集来自多层记录介质1的不同位置的主反射光束和伺服反射光束，其中主反射光束与主入射光束的传播方向相反，以及伺服入射光束与伺服反射光束的传播方向相反。
这里需要说明的是，本文中的主入射光束和主反射光束两者可以统称为主光束，该主光束可以用作写入光或读取光，而伺服入射光束和伺服反射光束两者可以通称为伺服光束或辅助光束。
为了便于依照上述写入和伺服控制方案实现对上述主光束和伺服光束的控制，在一些实施例中，上述第一物镜3-1和第二物镜3-2可以被设置在同一力矩器2上，并且适于随同该力矩器2的移动而同步移动。以这种方式，可以方便地协同主光束和辅助光束两者的移动，从而使得主光束和伺服光束的轨迹保持一致。在一些实施例中，力矩器2可以是三维力矩器。注意：在装配过程中，可以首先使得保证两个物镜的焦点大致处于同一水平位置来进行装配。
在读写过程中，可以通过力矩器2来控制两个物镜在聚焦、循迹以及倾斜三个维度上的位置偏差。通过调整物镜在垂直方向上的位置，可以控制焦点在盘片内的深度，保证焦点在数据记录层上移动。通过调整物镜在盘片径向上的位置，可以保证焦点在既定的轨道上写入数据。通过调整物镜与盘片的相对角度，可以保证激光垂直入射到盘片内部。
第一偏振分光镜9可以被布置在第一分束器13和第一物镜3-1之间，用于透射具有第一偏振的主入射光束，并且反射具有第二偏振的主反射光束。进一步地，经由第一偏振分光镜9反射的第二偏振的主反射光束可以被引导至第一探测器12，该第一探测器12可以输出指示主入射光束在多层记录介质1上的焦点位置和/或形状的第一探测结果，以用于主光束的反馈控制。在一些实施例中，第一探测器12可以是四象限探测器。为了实现利用像散法的探测，从第一偏振分光镜9反射的具有第二偏振的主反射光束可以经由准直镜10和柱透镜11的组合而入射至四象限探测器。在一些实施例中，主反射光束的光路可以与主入射光束的光路共享部分光学器件，例如第一 偏振分光镜9和物镜3-1，但应当理解，这不是必须的。
第二偏振分光镜14可以被布置在第一分束器13和第二物镜3-2之间，用于反射具有第一偏振的伺服入射光束，并且透射具有第二偏振的伺服反射光束。经由第二偏振分光镜14透射的伺服反射光束可以被引导至第二探测器21，该第二探测器21可以输出指示伺服入射光束在多层记录介质上的焦点位置和/或形状的第二探测结果，以用于伺服光的反馈控制。在一些实施例中，第二探测器21可以是四象限探测器。为了实现利用像散法的探测，从第二偏振分光镜14透射的具有第二偏振的伺服反射光束可以经由准直镜19和柱透镜20的组合而入射至四象限探测器。在一些实施例中，伺服反射光束的光路可以与伺服入射光束的光路共享部分光学器件，例如第二偏振分光镜9和物镜3-2，但应当理解，这不是必须的。
在一些实施例中，第一偏振和第二偏振可以彼此正交。例如，具有第一偏振的主入射光束和伺服入射光可以为s光，而具有第二偏振的主反射光束和伺服反射光束可以为p光。
为了实现上述具有第二偏振的主入射光束和伺服反射光束，在一些实施例中，第一1/4波片4-1可以被布置在第一偏振分光镜9和第一物镜3-1之间，以产生朝向第一偏振分光镜9的具有第二偏振的主反射光束。第二1/4波片4-2可以被布置在第二偏振分光镜14和第二物镜3-2之间，以产生朝向第二偏振分光镜11的具有第二偏振的伺服反射光束。在图8所示的示例中，第一1/4波片4-1和第二1/4波片4-2分别被示出布置在邻近第一物镜3-1和第二物镜3-2的位置。然而，应当理解，这仅仅示例，第一1/4波片4-1可以被布置在第一偏振分光镜9和第一物镜3-1之间的任何位置，以及第二1/4波片4-2可以被布置在第二偏振分光镜14和第二物镜3-2之间的任何位置。还应当理解，激光光束透射经过1/4波片4-1、4-2后，其从盘片反射，会再次经过1/4波片4-1、4-2，在这种情况下，两次经过1/4波片的激光偏振方向会旋转90°，这由此允许具有第二偏振的主反射光束从第一偏振分光镜9上反射，以及具有第二偏振的伺服反射光束从第二偏振分光镜14透射。
进一步地，在一些实施例中，读写光路100还可以包括第一补偿透镜组30，其可以被布置在第一偏振分光镜9和第一物镜3-1之间，并且能够被操作地以补偿主入射光束的焦点在所述多层记录介质内的深度变化所导致的折射率失配。作为示例，第一补偿透镜组30例如可以包括可移动的补偿镜7和固定透镜6的组合，其中补偿镜 7可以被布置在(一维)步进电机8上，从而实现对补偿镜的操作移动。在一些实施例中，步进电机8的运动方向可以与光的传播方向平行，其中激光透过补偿镜7的中心位置。可以理解，通过移动补偿镜7的位置例如可以补偿折射率失配的问题，保证盘片的焦点光斑形状接近于衍射极限，例如满足光斑能量RMS<0.07λ的要求。
在又一些实施例中，可以进一步分别在第一偏振分光镜9和第二偏振分光镜11之后设置反射镜5-1和5-2，以改变光束的传播方向，例如将光束从原来的水平方向改变为垂直方向，以更为方便地入射至多层记录介质。
下面结合图8来概要地描述一下主光束和伺服光束的行进光路以及读写的控制逻辑。
从激光源18发射具有第一偏振的激光束，激光束在经过第一分束器13的分束后形成具有第一偏振的主入射光束和伺服入射光束，主入射光束透射经过第一偏振分光镜9、第一补偿透镜组30、第一1/4波片后，经由第一物镜3-1入射至多层记录介质1的第一位置(例如，第一记录层L1上的位置)，第一物镜3-1收集来自第一位置的反射光以形成主反射光束，主反射光束再次反向穿过第一1/4波片4-1、第一补偿透镜组30后入射至第一偏振分光镜9。由于光束两次经过第一1/4波片4-1，主反射光束可以具有与第一偏振方向正交的第二偏振方向。第一偏振分光镜9反射具有第二偏振的主反射光束至第一探测器12。同时，伺服入射光束从第一分束器13入射至第二偏振分光镜14，后者可以被设计为反射具有第一偏振的伺服入射光束。经由第二偏振分光镜14反射的伺服入射光束穿过第二1/4波片4-2，并经由第二物镜3-2入射至多层记录介质1的第二位置(例如，伺服层L0上的位置)，第二物镜3-2收集来自第二位置的反射光以形成伺服反射光束，伺服反射光束再次反向穿过第二1/4波片4-2、入射至第二偏振分光镜14。由于光束两次经过第二1/4波片4-2，伺服反射光束可以具有与第一偏振方向正交的第二偏振方向。第二偏振分光镜14透射具有第二偏振的伺服反射光束至第二探测器21。
在写入的过程中，诸如四象限探测器的第二探测器21的信号可以用于控制力矩器2的聚焦、循迹和角度倾斜。当伺服光的焦点定位到所要写入的记录层Ln的相邻层Ln-1层后，诸如四象限探测器的第一探测器12可以调整第一补偿透镜组30(例如，通过一维步进电机8调整第一补偿透镜组30中的可移动补偿镜7的位置)，使主入射光束的焦点聚焦到记录层Ln，并修正折射率失配的问题。当开始进行写入时， 力矩器2将保持伺服光束的焦点沿着Ln-1层上的摆动轨道或数据轨道运动。由于两个物镜3-1和3-2被刚性固定在力矩器上，所以主光束的焦点也将沿着固定的轨道运动，保证写入的数据不会发生轨道串扰的情况。
在读取过程中，第二探测器21可以不再工作，可以仅使用第一探测器12获得的信号来控制力矩器2进行聚焦、循迹和倾斜伺服。同时控制步进电机8，调整第一补偿透镜组30，完成折射率失配的补偿。
图9示出了第二示例性读写光路200，其与图8的第一示例性读写光路100的区别在于：第二示例性读写光路200中增加了用于激光源的能量反馈系统40。
仅作为示例，该能量反馈系统40可以至少包括第二分束器22和第三探测器24，其中第二分束器22被布置在第一分束器13和第一偏振分光镜9之间，用于从来自第一分束器13的主入射光束中分出部分光，并将其引导至第三探测器24。第三探测器16接收并且检测从第二分束器22所分出的部分光，并且输出指示初始激光束的激光强度的第三探测结果，后者可以作为反馈结果来控制激光源18，以使其出射的激光光强保持稳定。作为示例，第三探测器16可以是光强探测器。在一些实施例中，透镜15还可以被设置在第二分束器22和第三探测器24之间，以便实现光斑的汇聚，从而便于第三探测器24的光强探测。
将会理解，图8和图9的示例性读写光路可以特别地适用于逐层制备并写入(即，层制备和写入并未分离)的多层记录介质。这是因为：当写入时，每次写入光可以聚焦在最表面的Ln层，而用于伺服的相邻记录层Ln-1到上述最表面的距离可以保持恒定。因此，伺服光可以不需要克服折射率失配问题。根据伺服光束的情况，物镜的完美焦点也可以被设计在次表面数据层上。与此同时，可以通过调整补偿镜7的位置，来保证主光束的完美焦点落在盘片表面。
图10示出了第三示例性读写光路300，其与图9的第二示例性读写光路200的区别在于，新增了针对伺服光束的第二补偿透镜组50。
仅作为示例，第二补偿透镜组50可以包括可移动补偿镜22和固定镜24，其中补偿镜22被布置在第二偏振分光镜14和第二物镜3-2之间，以便能够被操作地补偿伺服入射光束的焦点在所述多层记录介质内的深度变化所导致的折射率失配。在一些实施例中，可移动补偿镜22可以被布置在(例如，一维)步进电机23上，可以通过操作步进电机23来控制可移动补偿镜22的移动。类似于步进电机8，步进电机23 的运动方向可以与光的传播方向平行。在一些实施例中，步进电机23的控制可以由第二探测器21的信号和力矩器2的聚焦伺服方向施加的电压共同决定。
将会理解，在图10的示例中，主光束和伺服光束都各自具有补偿透镜组，这允许两个光束对各自在读写过程中出现的像差问题进行纠正或补偿，从而纠正折射率失配问题，保证两个物镜在盘片中的焦点满足衍射极限的要求。将会理解，图10的示例读写光路对于具有各种结构的多层记录介质都有很好的适应性，其尤其地可以是适应于逐层数据写入和制盘过程未分离的盘片、或者适应于预先制备好、写入和制盘过程分离的盘片。
以上已经详细地描述根据本公开的各个示例实施例的读写装置中的示例性光路。应当理解，本公开的读写装置可以不限于上述各个示例性读写光路，而是可以涵盖可以实现本公开的上述数据写入/伺服方法的更为广泛的读写装置。
譬如，在一些实施例中，该读写装置可以包括：伺服光路组件，其用于向多层记录介质中写有数据的第一记录层照射伺服入射光，并且接收经由所述第一记录层反射的伺服反射光，其中多次记录介质至少包括所述第一记录层和第二记录层；主光路组件，用于向所述第二记录层照射数据写入光；以及控制装置，其可以被配置成以所述伺服反射光作为伺服光，控制所述数据写入光以向第二记录层写入数据。
在又一些实施例中，上述主光路组件还可以用于向第一记录层照射第一写入光；上述伺服光路组件还可以向所述多层记录介质的伺服层照射另一伺服入射光，并且接收经由所述伺服层反射的另一伺服反射光；而控制装置还可以以所述另一伺服反射光作为伺服光，控制第一写入光以向所述第一纪录层写入数据。
作为上述主光路组件、伺服光路组件和控制装置实现的举例说明。仅作为示例，伺服光路组件例如可以包括如图8至图10中的伺服光束光路以及相关器件，该相关器件例如可以至少包括第二物镜3-2、第二偏振分光镜14、第二探测器21、第二1/4波片4-2、第二补偿透镜组50。主光路组件例如可以至少包括如图8至图10中的主光束光路以及相关器件，该相关器件例如可以至少包括第一物镜3-1、第一偏振分光镜9、第一1/4波片4-1、第一补偿透镜组30。而控制装置例如可以通过图4中的数字伺服算法实现模块、精密机械平台模块、模拟前放于驱动模块、上位PC机控制模块中的一者或多者来实现。
应当理解，可以对上述示例读写/伺服过程或读写装置(包括其内的光学器件) 的各个实施例或示例中的各个特征进行适当的额外设计或变型或组合，以考虑不同的应用场景(譬如，不同厚度的多层盘片、不同结构的盘片)，这种额外设计或变型或组合仍然落在本申请的范围之内。针对图10的新增加的独权进行了说明
例如，为增加读写系统可读写的范围，可以对物镜和力矩器进行设计，以使得当力矩器处于静态的情况下，物镜的焦点处于盘片可写区域的中心。又例如，对于盘片的读写区域和表面保护层的厚度一共为600μm的盘片，在不给力矩器施加电流的情况下，可以设计使得物镜的焦点处于距离表面300μm的位置。又例如，在设计物镜时，要考虑物镜的完美聚焦是在盘片内部，而不是空气中。
将会理解，与现有多层盘片的读写系统相比，本公开的方案可以具有以下的多种优点：
a.写入/伺服方案可以省去逐层制备反射层和摆动轨道等工艺，降低盘片的制备成本。记录层中略去反射层这一部分可以提升单记录层的透射率，进而增加单张盘片的记录层数和存储容量。此外，本公开的写入/伺服方案还可以保证在盘片容量提升的基础上依然能够高速读写。
b.只需要1个光源。伺服光和主光束的波长形态，由此物镜和其他光学器件的设计可以不考虑色差引起的光斑质量下降，这简化了设计和加工的难度。
c.本公开使用的伺服光也可以为405nm波长的蓝光，与现有的使用红光作为伺服光的方案相比，聚焦后的爱里斑更小，这有助于盘片面密度的提升，从而可以增加单张盘片的存储容量。
d.由于对伺服光和主光束进行聚焦的物镜刚性连接在力矩器上，两束光束的运动轨迹将保持一致，因此，主光束进行写入的数据不会发生窜轨的问题。另外，夹持双物镜的力矩器保证两个物镜刚性连接，且能满足驱动器高速响应的要求。
e.本公开的读写光路可以对聚焦选层时有可能产生的像差进行补偿，从而克服折射率失配的问题。
f.本公开的伺服方案和光路可以支持更多层的光盘进行读写操作。除了以对逐层制备的盘片进行读写外，还可以对没有制备读写层的块状材料进行读写。该制盘方式将降低盘片的制备成本，读写光路和伺服方案保证对盘片进行高速读写。
将会理解，上面描述的方法和装置仅仅是示例。尽管说明书中以特定的顺序描述了方法的步骤，但是这并非要求或者暗示必须按照该特定顺序来执行这些操作，或 是必须执行全部所示的操作才能实现期望的结果，相反，描绘的步骤可以改变执行顺序。附加地或备选地，可以省略某些步骤，将多个步骤合并为一个步骤执行，和/或将一个步骤分解为多个步骤执行。
虽然已经在附图和前述描述中详细说明和描述了本发明，但这些说明和描述应被认为是说明性的或示例性的而不是限制性的；本发明不限于所公开的实施例。本领域技术人员在实践所请求保护的发明中，通过研究附图、公开和所附权利要求可以理解并且实践所公开的实施例的其它变体。
在权利要求中，词语“包括”并不排除其它元件，并且不定冠词“一”或“一个”不排除多个。单个元件或其它单元可以满足在权利要求中阐述的多个项目的功能。仅在互不相同的实施例或从属权利要求中记载某些特征的仅有事实，并不意味着不能有利地使用这些特征的组合。在不脱离本申请的精神和范围的情况下，本申请的保护范围涵盖在各个实施例或从属权利要求中记载的各个特征任何可能组合。
此外，在权利要求中的任何参考标记不应被理解为限制本发明的范围。

Claims (20)

  1. 一种多层记录介质的数据写入方法，其特征在于，所述多层记录介质至少包括第一记录层和第二记录层，所述方法包括：
    使用数据写入光在所述第二记录层写入数据，其中以入射到写有数据的所述第一记录层的光作为所述数据写入光的伺服光。
  2. 根据权利要求1所述的数据写入方法，其特征在于，所述多层记录介质还包括伺服层，所述方法还包括：
    使用第一写入光在所述第一记录层写入数据，其中以入射到所述伺服层的光作为所述第一写入光的伺服光。
  3. 根据权利要求1所述的数据写入方法，其特征在于，所述第一记录层和所述第二记录层彼此相邻，并且所述第二记录层位于所述第一记录层之上。
  4. 根据权利要求1-3中任一项所述的数据写入方法，其中所述数据写入光以及其对应的伺服光波长相同。
  5. 根据权利要求2所述的数据写入方法，其特征在于，所述第一记录层为与所述伺服层邻接的记录层，所述多个记录层的数据写入顺序为从所述第一记录层开始的逐层写入。
  6. 根据权利要求1或2所述的数据写入方法，其特征在于，在写入过程中，所述伺服光和对应的所述数据写入光的运动轨迹保持一致。
  7. 根据权利要求2所述的数据写入方法，其特征在于，所述伺服层包括摆动沟槽轨道，所述使用第一写入光在所述第一记录层上写入数据包括：
    控制所述第一写入光对应的伺服光沿所述摆动沟槽轨道运动。
  8. 根据权利要求1或2所述的数据写入方法，其特征在于，所述使用所述数据写入光在所述第二记录层上写入数据包括：
    控制所述数据写入光对应的伺服光沿所述第一记录层的数据轨道移动。
  9. 根据权利要求4所述的数据写入方法，其特征在于，所述波长均为405nm。
  10. 一种读写装置，其特征在于，包括：
    伺服光路组件，用于向多层记录介质中写有数据的第一记录层照射伺服入射光，并且接收经由所述第一记录层反射的伺服反射光，其中，所述多次记录介质至少包括所述第一记录层和第二记录层；
    主光路组件，用于向所述第二记录层照射数据写入光；以及
    控制装置，用于以所述伺服反射光作为伺服光，控制所述数据写入光以向所述第二记录层写入数据。
  11. 根据权利要求10所述的读写装置，其特征在于，
    所述控制装置还用于在写入过程中控制所述数据写入光和对应的所述伺服光两者的运动轨迹保持一致。
  12. 根据权利要求10或11所述的读写装置，其特征在于，
    所述主光路组件还用于向所述第一记录层照射第一写入光，所述伺服光路组件还用于向所述多层记录介质的伺服层照射另一伺服入射光，并且接收经由所述伺服层反射的另一伺服反射光；
    所述控制装置还用于以所述另一伺服反射光作为伺服光，控制所述第一写入光以向所述第一纪录层写入数据。
  13. 根据权利要求10或11所述的读写装置，其特征在于，
    所述主光路组件包括第一物镜(3-1)，所述第一物镜适于将所述数据写入光聚焦至所述多层记录介质上的第二记录层；
    所述伺服光路组件包括第二物镜(3-2)，所述第二物镜适于将所述伺服入射光束聚焦至所述多层记录介质上的第一记录层。
  14. 根据权利要求13所述的读写装置，其特征在于，
    其中所述第一物镜(3-1)和所述第二物镜(3-2)被设置在同一力矩器(2)上，并且两者适于随同所述力矩器的移动而同步移动。
  15. 根据权利要求13所述的读写装置，其特征在于，还包括：
    激光源(18)，用于发射初始激光束；
    第一分束器(13)，用于将所述初始激光束分为主入射光束和伺服入射光束；
    第一偏振分光镜(9)，位于所述第一分束器和所述第一物镜之间，用于透射具有第一偏振的所述主入射光束，所述主入射光束作为所述数据写入光。
  16. 根据权利要求15所述的读写装置，其特征在于，还包括：
    第一补偿透镜组(30)，位于所述第一偏振分光镜和所述第一物镜之间，并且能够被操作地以补偿所述主入射光束的焦点在所述多层记录介质内的深度变化所导致的折射率失配。
  17. 一种用于多层记录介质的读写装置，其特征在于，包括：
    激光源(18)，用于发射初始激光束；
    第一分束器(13)，用于将所述初始激光束分为主入射光束和伺服入射光束；
    第一物镜(3-1)，用于将所述主入射光束聚焦至所述多层记录介质上的第一位置；以及
    第二物镜(3-2)，用于将所述伺服入射光束聚焦至所述多层记录介质上的第二位置，并且收集来自所述第二位置的伺服反射光束，所述第二位置不同于所述第一位置；
    其中所述第一物镜(3-1)和所述第二物镜(3-2)被设置在同一力矩器(2)上，并且两者适于随同所述力矩器的移动而同步移动。
  18. 根据权利要求17所述的读写装置，其特征在于，还包括：
    第一偏振分光镜(9)，位于所述第一分束器和所述第一物镜之间，用于透射具有第一偏振的所述主入射光束，并且反射具有第二偏振的所述主反射光束。
  19. 根据权利要求17或18所述的读写装置，其特征在于，还包括：
    第二偏振分光镜(14)，位于所述第一分束器和所述第二物镜之间，用于反射具有第一偏振的所述伺服入射光束，并且透射具有第二偏振的所述伺服反射光束。
  20. 根据权利要求18所述的读写装置，其特征在于，还包括：
    第一补偿透镜组(30)，位于所述第一偏振分光镜和所述第一物镜之间，并且能够被操作地以补偿所述主入射光束的焦点在所述多层记录介质内的深度变化所导致的折射率失配。
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002183985A (ja) * 2000-12-19 2002-06-28 Matsushita Electric Ind Co Ltd 光ディスク装置
CN1716394A (zh) * 2005-06-03 2006-01-04 清华大学 用于双光子三维盘式存储的自动调焦和道跟踪装置和方法
CN102163445A (zh) * 2010-02-22 2011-08-24 Tdk股份有限公司 光记录介质系列
CN104903959A (zh) * 2013-01-11 2015-09-09 富士胶片株式会社 多层光学信息记录盘及其制造方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20090062014A (ko) * 2007-12-12 2009-06-17 삼성전자주식회사 홀로그래픽 정보 기록/재생장치
EP2073202A1 (en) * 2007-12-21 2009-06-24 Deutsche Thomson OHG Holographic recording medium and pickup for this medium
JP5621227B2 (ja) * 2009-08-26 2014-11-12 ソニー株式会社 光情報装置及び光ピックアップ

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002183985A (ja) * 2000-12-19 2002-06-28 Matsushita Electric Ind Co Ltd 光ディスク装置
CN1716394A (zh) * 2005-06-03 2006-01-04 清华大学 用于双光子三维盘式存储的自动调焦和道跟踪装置和方法
CN102163445A (zh) * 2010-02-22 2011-08-24 Tdk股份有限公司 光记录介质系列
CN104903959A (zh) * 2013-01-11 2015-09-09 富士胶片株式会社 多层光学信息记录盘及其制造方法

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