A super-resolution three-dimensional optical storage focusing servo device and servo method thereof

Abstract

The present invention proposes a super-resolution three-dimensional optical storage focusing servo device and a servo method thereof. The device integrates a light source shaping module, a beam combining module, a zoom layer selection module, a servo signal detection module and a drive control module. The coaxial recording light is formed by combining solid excitation light and hollow suppressed light, and the servo guide layer reflects the signal generated by the solid servo light to control the axial movement of the servo objective lens and the recording objective lens, and the double beam center alignment is always maintained during the reading and writing process to achieve high-speed nano-focusing servo. No additional servo light source is required, and the focus of the double beam is adjusted in real time to maintain three-dimensional alignment, surpassing the diffraction limit and improving the storage density. Combined with the lens group to compensate for aberrations and zoom layer jump, ultra-high density storage of hundreds of layers is achieved. The device has a simple structure, convenient operation, good compatibility, and is applied to the field of super-resolution three-dimensional optical storage, with broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of optical storage, in particular to the field of super-resolution three-dimensional optical storage, and proposes a solution and a device structure for the multi-layer focusing servo problem of super-resolution three-dimensional optical storage. Background Art

[0002] In the era of big data, data has become a production factor as important as land, capital, and labor. With the rapid development of technologies such as artificial intelligence, metaverse, digital economy, and quantum computing, various emerging application scenarios have put forward higher requirements for the security, capacity, and efficiency of data storage. Especially for the military, political and legal, archives, medical, and financial industries, many sensitive data need to be stored for a long time or even permanently and cannot be tampered with. Optical storage technology relies on non-contact and offline reading and writing principles, and has the characteristics of safety, reliability, ultra-low energy consumption, and long life (>50 years). It is very suitable for long-term storage of massive data. However, traditional optical storage technology is limited by the optical diffraction limit, and the reflection-based reading and writing mechanism, resulting in a single-disc storage capacity of commercial Blu-ray discs of only hundreds of GB, and a maximum of 3 layers can be stored on a single side, which greatly hinders the widespread application of optical storage technology and related products in the big data market. In order to increase storage capacity, researchers at home and abroad have conducted a lot of research in multi-layer storage, multi-dimensional storage, multi-wavelength and multi-level storage, and holographic storage. However, these technologies have not essentially broken through the diffraction limit. No matter which technology is used, there is no way to truly achieve a milestone breakthrough in storage capacity. In addition, the cost is high and it is difficult to industrialize on a large scale.

[0003] In recent years, researchers have been committed to developing super-resolution three-dimensional optical storage technologies that break through the optical diffraction limit. Among them, dual-beam controlled aggregation-induced emission super-resolution optical storage technology is based on the dual-beam super-resolution principle. On the basis of traditional single-beam solid excitation light reading and writing, by introducing a second beam of hollow suppression light, it can modulate the range of action of the first beam of solid excitation light, and use the fluorescence contrast between the central area and the surrounding area of ​​the focal range to record information, forming information recording points with a size smaller than the diffraction limit, thereby achieving ultra-high-density storage. It can complete multi-layer recording of hundreds of layers, and the single-disk capacity has the potential of Pb level (see Nature, 2024, 626: 772-778).

[0004] However, the breakthrough of the diffraction limit does not mean the full arrival of a new generation of optical storage technology. On the road to industrialization, many problems need to be solved. First, unlike traditional commercial optical storage devices, the super-resolution three-dimensional optical storage system uses two beams to record information. One beam of solid excitation light reacts with the material to form information points, and the other beam of hollow suppression light (with zero center intensity) prevents the formation of information points, and finally forms information points of nanometer size that break through the diffraction limit. Therefore, whether in the writing or reading process, the solid excitation light and the hollow suppression light need to always maintain three-dimensional alignment. The existing focus servo only considers the tracking compensation of a single beam and cannot be applied to the super-resolution three-dimensional optical storage system. A matching focus servo device must be developed; secondly, in order to achieve ultra-high-density multi-layer storage, the recording medium of the super-resolution three-dimensional optical storage system is very transparent. Unlike the traditional commercial optical storage system based on the readout method of reflected light, the super-resolution three-dimensional optical storage system uses fluorescence readout. During the high-speed rotation of the optical disc, how to quickly position and zoom different layers, etc., all these problems put forward strict requirements on the focus servo control system of the super-resolution three-dimensional optical storage system. Existing servo solutions applied to super-resolution three-dimensional optical storage systems all introduce separate servo light, such as CN109524029B. In addition to the dual beams for reading and writing, the entire optical path system needs to use three lasers with different wavelengths, which need to be controlled separately. The system is complex and difficult to integrate. In addition, the focusing servo system of the system cannot monitor and compensate for the center position of the solid excitation light and the hollow suppression light to restore alignment. Once the focus of the dual beams deviates beyond a certain range (usually tens of nanometers), the super-resolution recording effect cannot be achieved, and the servo system will also lose its meaning. Therefore, there is an urgent need to develop a high-precision, simple-structured, and highly integrated focusing servo device and servo control method for super-resolution three-dimensional optical storage. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a super-resolution three-dimensional optical storage focusing servo device and a servo method thereof, which can accurately perform multi-layer focusing servo in the reading and writing process of super-resolution three-dimensional optical storage media.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides a super-resolution three-dimensional optical storage focusing servo device, comprising: a light source shaping module, used to form solid excitation light, hollow suppression light and solid servo light; a beam combining module, used to combine the solid excitation light and the hollow suppression light into a coaxial recording light with the center coincident; a zoom layer selection module, used to control the axial position of the coaxial recording light focusing spot and the axial position of the solid servo light focusing spot; a servo signal detection module, used to receive the reflected servo light generated after the solid servo light is reflected by the servo guide layer, and convert it into a servo reflection signal for monitoring; a recording signal detection module, used to detect the fluorescent signal generated by the coaxial recording light in the information recording layer;

[0007] A drive control module is used to receive the servo reflection signal and the fluorescence signal, and drive the beam combining module to perform aberration compensation on the solid excitation light and the hollow suppression light according to the fluorescence signal until the focusing centers of the two are aligned; and drive the objective lens of the zoom layer selection module to move axially according to the servo reflection signal, so as to focus the solid servo light on the servo guide layer of the optical storage medium, and focus the coaxial recording light on the selected information recording layer of the optical storage medium.

[0008] According to a specific embodiment of the present invention, the zoom layer selection module includes a recording objective lens and a servo objective lens. The recording objective lens is used to control the axial position of the coaxial recording light focusing spot, and the servo objective lens is used to control the axial position of the solid servo light focusing spot. The axial movement of the servo objective lens can link or trigger the recording objective lens to make corresponding axial movement in time; the drive control module drives the servo objective lens to move axially according to the servo reflection signal, and at the same time links or triggers the recording objective lens to move axially.

[0009] Preferably, the recording objective lens and the servo objective lens are rigidly connected to keep the relative position between them stable, thereby achieving more precise focus tracking servo.

[0010] In addition, the connection method between the recording objective lens and the servo objective lens is not limited to a rigid connection. As long as the recording objective lens can make corresponding axial movements in time according to the movement of the servo objective lens to achieve the function of focusing tracking servo, other forms of connection or non-connection synchronization movement mechanisms can be adopted.

[0011] Preferably, the numerical aperture of the objective lens of the zoom layer selection module is not less than 0.65.

[0012] In the present invention, "axial direction" refers to the optical axis direction.

[0013] The optical storage medium is a multi-layer structure, including multiple information recording layers and a servo guide layer containing spiral grooves. Preferably, the components of the information recording layer include photoinitiators, monomers, metal ion compounds and aggregation-induced luminescence dyes.

[0014] According to a specific embodiment of the present invention, the light source shaping module includes a light source unit and a shaping unit, the light source unit emits laser light, and the beam is split by the shaping unit to generate solid excitation light, hollow suppression light and solid servo light. Preferably, the light source unit includes at least a laser light source of a single wavelength, or laser light sources of different wavelengths, which emits two incident laser beams into the shaping unit; the shaping unit splits and shapes the two incident laser beams, thereby generating a beam of solid excitation light, a beam of hollow suppression light and a beam of solid servo light.

[0015] Preferably, the solid servo light has the same wavelength as the solid excitation light or the hollow suppression light. According to a specific embodiment of the present invention, the solid servo light shares the same laser light source with the solid excitation light or shares the same laser light source with the hollow suppression light.

[0016] According to a specific embodiment of the present invention, the shaping unit includes a beam splitter, a collimating lens group, and a phase plate. The beam splitter is used to split an incident laser beam into at least two light beams. The collimating lens group is used to collimate each light beam. The phase plate is used to perform phase modulation on the collimated light beam to form a hollow suppression light.

[0017] The beam combining module comprises a dichroic mirror, and the dichroic mirror is used to combine light beams from different paths into one light beam;

[0018] The zoom layer selection module includes a compensation lens and an objective lens, wherein the compensation lens is used to adjust the focus of each light beam, and the objective lens is used to adjust the axial position of the focus spot of each light beam;

[0019] The driving control module includes a displacement actuator and a controller, wherein the controller is used to receive signals and send instructions to the displacement actuator, and the displacement actuator drives the zoom layer selection module and / or the beam combining module to perform precise adjustments according to the instructions;

[0020] The recording signal detection module includes a first filter and a first photodetector, wherein the first filter is used to filter out unnecessary light of a specific wavelength to ensure the purity of the fluorescent signal; and the first photodetector is used to detect the fluorescent signal after passing through the first filter;

[0021] The servo signal detection module includes a second filter, an astigmatic lens and a second photodetector. The second filter is used to filter out unnecessary light of a specific wavelength from the reflected servo light. The astigmatic lens is used to modulate the reflected servo light so that when the coaxial recording light focusing spot is on the selected information recording layer or deviates from the selected information recording layer, the shape of the spot formed by the reflected servo light on the second photodetector is different. The second photodetector is used to detect the reflected servo light after passing through the second filter and the astigmatic lens and convert it into a servo reflection signal for monitoring.

[0022] According to a specific embodiment of the present invention, the light source unit includes a first light source and a second light source; the shaping unit includes a first collimating lens, a second collimating lens, a beam splitter, a 1 / 2 wave plate, a first 1 / 4 wave plate, a phase plate, a first reflector, and a polarization beam splitter; the beam combining module includes a first focusing lens, a first compensation lens, a first dichroic mirror, a second dichroic mirror, a second focusing lens, a second compensation lens, and a second reflector; the zoom layer selection module includes a third focusing lens, a third compensation lens, a recording objective lens, a fourth focusing lens, a fourth compensation lens, a second 1 / 4 wave plate, and a servo objective lens; the drive control module includes a controller, a first displacement actuator, a second displacement actuator, a third displacement actuator, a fourth displacement actuator, A fifth displacement actuator; the servo signal detection module includes a second filter, an astigmatic lens, a second optical fiber, and a second photodetector; the light beam output by the first light source forms a solid excitation light after passing through the first collimating lens; the light beam output by the second light source is incident on the beam splitter through the second collimating lens to form a first transmitted light and a second transmitted light, the first transmitted light is incident on the phase plate through the 1 / 2 wave plate and the first 1 / 4 wave plate in sequence to form a hollow suppression light in a first circular polarization state, the second transmitted light is incident on the polarization beam splitter through the first reflector, and is transmitted through the polarization beam splitter to form a solid servo light with a first linear polarization state; the solid excitation light is incident on the first dichroic mirror through the first focusing lens and the first compensation lens in sequence, and is reflected by the first dichroic mirror to form a first circular polarization state. The first reflected light is incident on the second dichroic mirror, and is transmitted through the second dichroic mirror to form a third transmitted light; the hollow suppression light passes through the second focusing lens and the second compensation lens in sequence and is incident on the second dichroic mirror, and is reflected by the second dichroic mirror to form a second reflected light; the second reflected light and the third transmitted light are combined by the second dichroic mirror, and are reflected by the second reflection mirror to form a third reflected light; the third reflected light passes through the third focusing lens, the third compensation lens, and the recording objective lens in sequence and is incident on the Mth information recording layer of the optical storage medium, and excites and generates a fluorescent signal in the focusing area; the solid servo light passes through the fourth focusing lens and the fourth compensation lens in sequence and is incident on the second 1 / 4 wave plate, and becomes a fourth transmitted light with a second circular polarization state; the fourth The transmitted light is incident on the servo guide layer of the optical storage medium through the servo objective lens, and is reflected by the servo guide layer to form a fourth reflected light with a third circular polarization state; the fourth reflected light is incident on the second 1 / 4 wave plate through the servo objective lens, and is converted into a fifth transmitted light with a second linear polarization state through the second 1 / 4 wave plate; the fifth transmitted light is incident on the polarization beam splitter through the fourth compensation lens and the fourth focusing lens in sequence, and is reflected by the polarization beam splitter to form a fifth reflected light; the fifth reflected light is sequentially transmitted through the second filter, the astigmatism lens, and the second optical fiber to reach the second photodetector, and is converted into a servo reflection signal through the second photodetector; the second photodetector is connected to the controller; the second photodetector monitors the servo reflection signal and sends it to the controller;The controller controls the third displacement actuator to drive the third compensation lens to move axially, the fourth displacement actuator to drive the fourth compensation lens to move axially, and the fifth displacement actuator to drive the recording lens and the servo lens to move axially according to the received servo reflection signal.

[0023] According to a specific embodiment of the present invention, the recording signal control module includes a first filter, a fifth focusing lens, a first optical fiber, and a first photodetector; after the fluorescence signal is collected by the recording objective lens, it is incident on the second reflector through the third compensation lens and the third focusing lens in sequence, and is reflected by the second reflector to form a sixth reflected light; the sixth reflected light passes through the second dichroic mirror, the first dichroic mirror, the first filter, the fifth focusing lens, and the first optical fiber in sequence to reach the first photodetector; the first filter transmits the fluorescence signal and filters out the solid excitation light and the hollow inhibition light; the first photodetector is connected to the controller; the first photodetector detects the fluorescence signal and sends it to the controller; the controller controls the first displacement actuator to drive the first compensation lens to move axially and the second displacement actuator to drive the second compensation lens to move axially according to the received fluorescence signal.

[0024] Preferably, the first linear polarization state and the second linear polarization state are perpendicular to each other.

[0025] Furthermore, the focusing servo device further comprises a spindle motor, and the spindle motor is used to control the high-speed rotation of the optical storage medium; the drive control module controls the rotation speed of the spindle motor according to the received servo reflection signal or fluorescent signal.

[0026] The present invention also provides a three-dimensional optical storage focusing servo method based on the above-mentioned focusing servo device, comprising the following steps:

[0027] A light source shaping module is used to form solid excitation light, hollow suppression light and solid servo light;

[0028] A beam combining module is used to combine solid excitation light and hollow suppressed light beam into coaxial recording light with overlapping centers;

[0029] The coaxial recording light and the solid servo light are focused on the Mth information recording layer and the servo guide layer of the optical storage medium respectively by using a zoom layer selection module, where M is an integer;

[0030] Using a servo signal detection module to monitor a servo reflection signal generated by the solid servo light being reflected by the servo guide layer and send the signal to a drive control module;

[0031] If the servo reflection signal is not within the set range, the drive control module is used to drive the recording objective lens and the servo objective lens of the zoom layer selection module to move axially together according to the servo reflection signal until the servo reflection signal detected by the servo signal detection module is within the set range, thereby refocusing the solid servo light on the servo guide layer of the optical storage medium and refocusing the coaxial recording light on the Mth information recording layer of the optical storage medium; wherein the recording objective lens is used to control the axial position of the focusing spot of the coaxial recording light, and the servo objective lens is used to control the axial position of the focusing spot of the solid servo light;

[0032] A recording signal detection module is used to detect the fluorescent signal generated by the coaxial recording light in the information recording layer and send it to a drive control module; if the focusing center positions of the solid excitation light and the hollow suppression light are offset, the drive control module drives the beam combining module to perform aberration compensation on the solid excitation light and the hollow suppression light according to the fluorescent signal until the focusing centers of the two are aligned; wherein the fluorescent signal is used as a feedback signal to indicate whether there is an offset between the focusing center positions of the solid excitation light and the hollow suppression light.

[0033] According to a specific embodiment of the present invention, the drive control module includes a controller, a first displacement actuator and a second displacement actuator; the controller controls the first displacement actuator to drive the first compensation lens of the beam combining module to move axially, and the second displacement actuator to drive the second compensation lens of the beam combining module to move axially according to the received fluorescence signal; wherein, the aberration compensation of the solid excitation light is achieved by the axial movement of the first compensation lens; and the aberration compensation of the hollow suppression light is achieved by the axial movement of the second compensation lens.

[0034] According to a specific embodiment of the present invention, after receiving a zoom jump layer request, the drive control module drives the third compensation lens of the zoom layer selection module to move axially, and drives the recording objective lens and the servo objective lens to move axially together, so that the focus of the solid excitation light and the hollow inhibition light moves to the Nth information recording layer; then drives the fourth compensation lens of the zoom layer selection module to move axially, so that the focus of the solid servo light is restored to the servo guide layer; wherein N is an integer, and N≠M.

[0035] According to a specific embodiment of the present invention, the drive control module includes a controller and a third displacement actuator, a fourth displacement actuator and a fifth displacement actuator; after receiving a zoom layer jump request, the controller outputs a preset constant bias voltage to the third displacement actuator, the fourth displacement actuator and the fifth displacement actuator respectively; the third displacement actuator drives the third compensation lens to move axially, and the fifth displacement actuator drives the recording objective lens and the servo objective lens to move axially together, so that the focus of the solid excitation light and the hollow suppression light moves to the Nth information recording layer; then the fourth displacement actuator drives the fourth compensation lens to move axially, so that the focus of the solid servo light is restored to the servo guide layer.

[0036] As described above, the super-resolution three-dimensional optical storage focusing servo device and servo method of the present invention have the following beneficial effects:

[0037] (1) During the reading and writing process, the focus of the solid excitation light and the hollow suppression light can be adjusted in real time through the focus control of the servo reflection signal and the fluorescence signal, so that the two beams are always aligned in three dimensions and focused on the selected information recording layer, thereby achieving the recording of nano-information dots beyond the optical diffraction limit, greatly improving the storage density of the optical disc;

[0038] (2) By combining the lens group to compensate for aberrations and zoom in and out, it is possible to achieve ultra-high-density three-dimensional data storage of up to 100 layers.

[0039] (3) Compared with the existing servo solutions applied to super-resolution three-dimensional optical storage systems, the present invention does not need to add a separate servo light source, and can complete high-speed nano-focusing servo based on the dual-beam reading and writing system;

[0040] (4) The present invention has a simple structure, is easy to operate, and has good compatibility with other servo control systems such as tracking servo, speed servo, tilt servo, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram showing the overall structure of a super-resolution three-dimensional optical storage focusing servo device proposed by the present invention;

[0042] Figure 2 A schematic diagram showing a specific implementation of the focus servo device of the present invention;

[0043] Figure 3 It is a schematic diagram showing the focusing spots of the coaxial recording light and the solid servo light during the zoom layer jump process of the present invention;

[0044] Figure 4 Shown is a workflow diagram of a super-resolution three-dimensional optical storage zoom layer hopping method of the present invention;

[0045] Figure 5 Shown is a workflow diagram of a super-resolution three-dimensional optical storage focusing servo method of the present invention.

[0046] Component number description

[0047] 001 Super-resolution optical disc

[0048] 002 Mth Information Recording Layer

[0049] 003 Nth Information Recording Layer

[0050] 004 Servo guide layer

[0051] 10 Light source shaping module

[0052] 100 Light source units

[0053] 101 First Light Source

[0054] 102 Second Light Source

[0055] 200 Shaping Units

[0056] 201 First collimating lens

[0057] 202 second collimating lens

[0058] 203 beam splitter

[0059] 204 1 / 2 wave plate

[0060] 205 First 1 / 4 wave plate

[0061] 206 Phase Plate

[0062] 207 First Reflector

[0063] 208 Polarization Beam Splitter

[0064] 301 solid excitation light

[0065] 302 Hollow Suppression Light

[0066] 303 Solid Servo Light

[0067] 40 beam combining module

[0068] 401 First focusing lens

[0069] 402 Second focusing lens

[0070] 403 First compensation lens

[0071] 404 Second compensation lens

[0072] 405 First dichroic mirror

[0073] 406 Second dichroic mirror

[0074] 407 Second Reflector

[0075] 50 Zoom layer selection module

[0076] 501 Third focusing lens

[0077] 502 Fourth focusing lens

[0078] 503 Third compensation lens

[0079] 504 Fourth compensation lens

[0080] 505 Recording lens

[0081] 506 Second 1 / 4 wave plate

[0082] 507 Servo Objective

[0083] 60 Drive control module

[0084] 601 First displacement actuator

[0085] 602 Second displacement actuator

[0086] 603 Third displacement actuator

[0087] 604 Fourth displacement actuator

[0088] 605 Fifth displacement actuator

[0089] 606 Controller

[0090] 607 Spindle Motor

[0091] 70 Recording signal detection module

[0092] 701 First filter

[0093] 702 Fifth focusing lens

[0094] 703 First Fiber

[0095] 704 First Photodetector

[0096] 80 Servo signal detection module

[0097] 801 Second filter

[0098] 802 Astigmatic Lens

[0099] 803 Second optical fiber

[0100] 804 Second photodetector. DETAILED DESCRIPTION

[0101] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0102] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0103] A further detailed description will be given below in conjunction with the accompanying drawings.

[0104] In the following specific implementations, a super-resolution optical disc is selected as a super-resolution three-dimensional optical storage medium.

[0105] The overall structure of a super-resolution three-dimensional optical storage focusing servo device proposed by the present invention is shown in FIG1 . The device is suitable for super-resolution three-dimensional optical storage media. The entire device consists of six modules, namely, a light source shaping module 10, a beam combining module 40, a zoom layer selection module 50, a drive control module 60, a recording signal detection module 70, and a servo signal detection module 80.

[0106] The light source shaping module 10 includes a light source unit 100 and a shaping unit 200 .

[0107] The super-resolution three-dimensional optical storage focusing servo device proposed in the present invention can act on optical storage systems based on various dual-beam super-resolution principles, for example, based on the stimulated emission loss principle, the edge light suppression principle, the triplet-triplet absorption principle, etc. The wavelength of the dual-beam used for recording is selected according to the principle and material properties. Therefore, the light source unit 100 includes at least one wavelength of laser light source, or laser light sources of different wavelengths, which emit two incident laser beams into the shaping unit 200;

[0108] The shaping unit 200 at least includes a beam splitter, a collimating lens group, and a phase plate, and its function is to split and shape two incident laser beams, thereby generating a solid excitation light beam 301, a hollow suppression light beam 302, and a solid servo light beam 303. The solid servo light 303 has the same wavelength as the solid excitation light 301 or the hollow suppression light 302, that is, the solid servo light 303 and the solid excitation light 301 share the same laser light source, or the solid servo light 303 and the hollow suppression light 302 share the same laser light source;

[0109] The beam combining module 40 at least includes a dichroic mirror, which is used to combine the solid excitation light 301 and the hollow suppression light 302 and then jointly incident on the zoom layer selection module 50;

[0110] The zoom layer selection module 50 at least includes a compensation lens and an objective lens, and is used to control the axial position of the focus spot;

[0111] The drive control module 60 at least includes a displacement actuator and a controller, which drives the zoom layer selection module 50 to move, focuses the solid excitation light 301 and the hollow suppression light 302 together on the selected information recording layer of the super-resolution optical disc 001, and focuses the solid servo light 303 on the servo guide layer of the super-resolution optical disc 001;

[0112] The recording signal detection module 70 at least includes a filter and a photodetector, and detects the fluorescence signal generated by the solid excitation light 301 and the hollow suppression light 302 in the information recording layer.

[0113] The servo signal detection module 80 at least includes a filter, an astigmatic lens and a photodetector, and monitors the servo reflection signal generated when the solid servo light 303 is reflected by the servo guide layer.

[0114] The above modules are connected by optical or electrical signals. The light source unit 100 includes two light sources, each emitting a laser beam, which passes through the shaping unit 200 to obtain three laser beams: a solid excitation light beam 301, a hollow suppression light beam 302, and a solid servo light beam 303. The solid excitation light 301 and the hollow suppression light 302 are coupled through the beam combining module 40 and enter the zoom layer selection module 50, where they are focused on the selected information recording layer of the super-resolution optical disc 001, and react with the medium of the recording layer to generate a fluorescence signal, which is detected by the recording signal detection module 70 through the zoom layer selection module 50, and the detection result is transmitted to the drive control module 60; while the solid servo light 303 is focused by the zoom layer selection module 50 on the servo guide layer of the super-resolution optical disc, and after reflection, it passes through the zoom layer selection module 50 again, and is then detected by the servo signal detection module 80, and the detection result is transmitted to the drive control module 60; the drive control module 60 calculates and issues instructions based on the detection results, controls the beam combining module 40 and the zoom layer selection module 50, and realizes focusing servo control.

[0115] Furthermore, since the super-resolution three-dimensional optical storage system includes writing and reading functions, when the writing function is used alone, the super-resolution three-dimensional optical storage system can be regarded as a super-resolution three-dimensional laser direct writing system; when the reading function is used alone, the super-resolution three-dimensional optical storage system can be regarded as a super-resolution three-dimensional microscopic imaging system. Therefore, the present invention can also be used in the fields of super-resolution three-dimensional laser direct writing focusing servo and super-resolution three-dimensional microscopic imaging focusing servo.

[0116] FIG. 2 shows a specific implementation of the focusing servo device of the present invention. Figure 2 As shown, the super-resolution optical disc that the device is suitable for reading and writing has a multi-layer structure, including a recording layer and a servo guide layer located below the recording layer, wherein the recording layer is an aggregation-induced luminescence dye-doped photoresist with a thickness greater than 100 μm, which can be regulated by double beams to produce nano information dots that break through the optical diffraction limit size and emit fluorescence, and have high transparency and high uniformity. In order to achieve ultra-high density multi-layer storage, the recording layer is designed to include multiple information recording layers (for example, the Mth information recording layer 002, the Nth information recording layer 003), and the bottom layer of the super-resolution optical disc 001 has a spiral groove-shaped servo guide layer 004, and the surface of the servo guide layer is plated with a reflective material.

[0117] For super-resolution optical disc information writing, two wavelengths are used, λ 1 With λ 2 The light source, where λ 1 The laser with wavelength will produce photopolymerization effect in the focused area of ​​the recording layer, and λ 2 The wavelength of the laser light will suppress the photopolymerization effect in the focused area of ​​the recording layer;

[0118] From λ 1 The laser light emitted by the first light source 101 with a wavelength of 2 The laser emitted by the second light source 102 with a wavelength passes through the second collimating lens 202 and the beam splitter 203 to form a first transmitted light and a second transmitted light. The first transmitted light passes through the 1 / 2 wave plate 204, the first 1 / 4 wave plate 205 and the phase plate 206 to form a hollow suppression light with a circular polarization state and a central light intensity of zero. The second transmitted light passes through the first reflector 207 and the polarization beam splitter 208 to form a solid servo light with a linear polarization state (s-polarization).

[0119] The first dichroic mirror 405 is coupled to λ 1 Reflection, the second dichroic mirror 406 to λ 2 Reflection and transmission 1Therefore, the solid excitation light and the hollow suppression light are coupled into one optical path, the first focusing lens 401 and the first compensation lens 403 jointly compensate the aberration of the solid excitation light, and the second focusing lens 402 and the second compensation lens 404 jointly compensate the aberration of the hollow suppression light, thereby ensuring that the solid excitation light and the hollow suppression light are three-dimensionally aligned after being focused by the recording objective lens 505 during the writing process, so as to achieve the best effect of super-resolution three-dimensional optical storage;

[0120] After the coaxial recording light composed of the solid excitation light and the hollow suppression light is reflected by the second reflector 407, the third focusing lens 501 and the third compensation lens 503 together compensate the aberration of the coaxial recording light, so that it is focused on the Mth information recording layer 002 of the super-resolution optical disc 001 after passing through the recording objective lens 505, and nano information dots are formed within the exposure time to complete the writing of information;

[0121] During the writing process of the super-resolution optical disc, due to the disc jitter, eccentricity and other errors caused by high-speed rotation, external environmental vibration, etc., the focusing center of the solid excitation light and the hollow suppression light deviates from the recording layer, which can easily cause the wrong writing of information or even loss. Therefore, it is necessary to add a focusing servo with nanometer precision. The fourth focusing lens 502 and the fourth compensation lens 504 jointly compensate the aberration of the s-polarized solid servo light so that it is focused on the servo guide layer 004 below the super-resolution optical disc 001 after passing through the second 1 / 4 wave plate 506 and the servo objective lens 507. The servo guide layer 004 has a high reflection characteristic for the solid servo light. After reflection, it passes through the second 1 / 4 wave plate 506. At this time, the reflected servo light becomes p Polarized light is therefore separated from the emitted servo light when passing through the polarization beam splitter 208. After the stray light is filtered out by the second filter 801, it is focused into the second optical fiber 803 by the astigmatism lens 802 and collected by the second photodetector 804. The second photodetector 804 uses an avalanche photodiode four-quadrant photodetector, which can amplify and detect the collected light signal to generate a servo reflection signal, which is then input into the controller 606. The controller 606 adjusts the fifth displacement actuator 605 (specifically, it can be a voice coil motor) to drive the servo objective lens 507 to move axially, so that the focusing error is reduced to 0. Since the recording objective lens 505 is rigidly connected to the servo objective lens 507, the recording objective lens 505 also moves axially together to realize focus tracking servo.

[0122] For the information readout of super-resolution optical discs, in order to maintain the long-term reliability of information, two other wavelengths are used, namely, λ 3 With λ 4 The light source, where λ 3 When the laser of wavelength is focused on the nano information point, it will produce aggregation induced emission effect, enhancing the fluorescence intensity, and λ 4 When the laser with wavelength is focused on the nano information point, the aggregation-induced emission effect will be suppressed. 3 With λ4 The lasers of different wavelengths do not produce fluorescence or only produce weak fluorescence in the unwritten area. The optical path of the readout is basically the same as the writing setting. 3 Wavelength of solid excitation light and λ 4 The hollow suppression light of wavelength is focused to the Mth information recording layer 002 of the super-resolution optical disc 001 after passing through the recording objective lens 505. Due to the focus-induced luminescence effect, a strong fluorescence signal is emitted when irradiating the information recording point area. After the fluorescence signal passes through the recording objective lens 505, the third compensation lens 503, the third focusing lens 501, and the second reflecting mirror 407, the second dichroic mirror 406 and the first dichroic mirror 405 both transmit the fluorescence signal, while reflecting λ 4 wavelength of hollow suppressed light and λ 3 The solid excitation light of wavelength is separated from the solid excitation light and hollow inhibition light, and then filtered by the first filter 701 and focused by the fifth focusing lens 702, only the fluorescence signal reaches the first optical fiber 703 and is collected by the first photodetector 704. The optical fiber is equivalent to a small hole, so that the incident end face of the optical fiber and the focus of the system are in a confocal position, that is, only the fluorescence / reflected light emitted at the focus of the system can reach the first photodetector 704, and other illuminated areas are blocked because they are not at the focus, thereby enhancing the signal-to-noise ratio and avoiding crosstalk between adjacent recording points, thereby completing the information reading. In addition, during the reading process, the focus tracking servo is always working to ensure the correct reading of information.

[0123] During the reading / writing process of the optical disc, the high-speed rotation of the optical disc is controlled by the spindle motor 607. The controller 606 controls the rotation speed of the spindle motor 607 according to the received servo reflection signal or fluorescent signal to make the signal transmission more stable and further ensure the accuracy of the focusing servo.

[0124] Figure 3 Schematic diagram of the focusing spot of the coaxial recording light and the solid servo light during the zoom layer jump process. Figure 2 By applying Newton's formula and scanning calibration test, the corresponding relationship between the displacement of each compensation lens and objective lens and the focus movement can be calculated and pre-stored respectively, based on the geometric optical relationship among the first compensation lens 403, the second compensation lens 404, the third compensation lens 503 and the recording objective lens 505, and the fourth compensation lens 504 and the servo objective lens 507.

[0125] When reading / writing the Mth information recording layer 002, the coaxial recording light composed of the solid excitation light and the hollow suppression light is focused by the recording objective lens 505 onto the Mth information recording layer 002 of the super-resolution optical disc 001, and the fluorescence signal that breaks through the diffraction limit is excited and collected by the first photodetector 704 to become a recording signal; the solid servo light is focused by the servo objective lens 507 onto the servo guide layer 004 below the super-resolution optical disc 001, and the reflected light signal is collected by the second photodetector 804 to become a servo reflection signal. The first photodetector 704 and the second photodetector 804 are connected to the controller 606, which contains a control algorithm. The focusing center positions of the solid excitation light and the hollow suppression light can be calculated through analysis. When the centers of the two are found to be deviated, the controller 606 controls the first displacement actuator 601 to drive the first compensation lens 403 to move along the axial direction, and the second displacement actuator 602 to drive the second compensation lens 404 to move along the axial direction according to the received fluorescence signal. The solid excitation light is compensated for aberration by the axial movement of the first compensation lens 403; the hollow suppression light is compensated for aberration by the axial movement of the second compensation lens 404 until the focus centers of the two are aligned. During the high-speed rotation of the super-resolution optical disc, the focus spots of the coaxial recording light and the solid servo light may deviate due to disc jitter, warping, etc. The controller 606 monitors the servo reflection signal in real time and outputs a focus error compensation signal command to control the fifth displacement actuator 605, so that it drives the recording lens 505 and the servo lens 507 to move axially together, so that the focus error is reduced to 0, and the focus tracking servo on the Mth information recording layer 002 is realized.

[0126] After the controller 606 receives the request to zoom to the Nth information recording layer 003, it additionally loads a constant bias voltage to the fifth displacement actuator 605 while receiving the focus error compensation signal, so as to move the focus of the coaxial recording light to the Nth information recording layer 003. At the same time, the third displacement actuator 603 and the fourth displacement actuator 604 are respectively loaded with a constant bias voltage to drive the third compensation lens 503 and the fourth compensation lens 504 to move axially, compensate the aberration, so that the restored solid servo light is focused by the servo objective lens 507 to the servo guide layer 004 below the super-resolution optical disc 001. The controller 606 continuously monitors the focus center position of the solid excitation light and the hollow suppression light and the servo reflection signal, and repeats the above process. In addition, when writing information, not only the user data is recorded on the super-resolution optical disc 001, but also the position of these data in the super-resolution optical disc 001, including the layer information and the sector information, is recorded therein, so that the required data can be quickly found on the super-resolution optical disc 001 when reading.

[0127] Figure 4 The flowchart of the super-resolution three-dimensional optical storage zoom layer hopping method of the present invention is shown. It mainly includes the following steps:

[0128] Step 1: The light source unit emits laser light, which is split by the shaping unit to generate solid excitation light, hollow suppression light and solid servo light;

[0129] Step 2: The solid excitation light and the hollow suppression light are coupled and focused on the Mth information recording layer of the optical disc, and the solid servo light is focused on the servo guide layer of the optical disc;

[0130] Step 3: The controller monitors the focus center positions of the solid excitation light and the hollow inhibition light. If there is a deviation, the controller drives the first compensation lens and the second compensation lens to perform aberration compensation on the solid excitation light and the hollow inhibition light respectively until the focus centers of the two are aligned;

[0131] Step 4: After receiving the zoom layer jump request, the controller outputs a preset constant bias voltage to the third displacement actuator, the fourth displacement actuator and the fifth displacement actuator respectively;

[0132] Step 5: The third displacement actuator drives the third compensation lens to move axially, and the fifth displacement actuator drives the recording objective lens and the servo objective lens to move axially together, so that the focus of the solid excitation light and the hollow suppression light moves to the Nth information recording layer;

[0133] Step 6: The fourth displacement actuator drives the fourth compensation lens to move axially, so that the focus of the solid servo light is restored to the servo guide layer, ensuring that the solid servo light is always focused on the servo guide layer;

[0134] The above steps are used to complete the zoom layer jump from the Mth information recording layer to the Nth information recording layer. Steps 1 to 6 are repeated to achieve multi-layer recording.

[0135] Figure 5 The flowchart of the super-resolution three-dimensional optical storage focusing servo method of the present invention is shown. It mainly includes the following steps:

[0136] Step 1: The light source unit emits laser light, which is split by the shaping unit to generate solid excitation light, hollow suppression light and solid servo light;

[0137] Step 2: After the solid excitation light and the hollow suppression light are coupled, they are focused on the selected information recording layer through the recording objective lens, and the solid servo light is focused on the servo guide layer through the servo objective lens;

[0138] Step 3: The servo signal detection module detects the reflected servo light of the solid servo light, thereby obtaining a focus error and sending the detection result of the focus error to the controller;

[0139] Step 4: The controller controls the fifth displacement actuator according to the detection result to drive the recording objective lens and the servo objective lens to move along the axial direction together until the focusing error is within a set range;

[0140] Step 5: During the high-speed rotation of the optical disc, the recording signal detection module detects the fluorescent signal generated in the information recording layer after the coupling of the solid excitation light and the hollow suppression light and sends it to the controller; if the focusing center positions of the solid excitation light and the hollow suppression light are offset, the controller drives the first compensation lens and the second compensation lens to perform aberration compensation on the solid excitation light and the hollow suppression light respectively until the focusing centers of the two are aligned.

[0141] The fluorescence signal is used as a feedback signal to indicate whether there is an offset between the focus center positions of the solid excitation light and the hollow inhibition light.

[0142] Through the above operation, during the high-speed rotation of the optical disc, the focusing centers of the solid excitation light and the hollow suppression light are aligned and maintained on the selected information recording layer, completing the focusing servo.

[0143] In summary, a super-resolution three-dimensional optical storage focusing servo device and its servo method of the present invention utilizes a servo reflection signal reflected by a servo guide layer to control the axial movement of the objective lens, and combines the lens group to compensate for the aberration to complete the zoom layer jump, and in the reading and writing process, the focus of the solid excitation light and the hollow suppression light can be adjusted in real time, and the three-dimensional alignment of the two light beams is always maintained, so as to accurately realize ultra-high-density three-dimensional data optical storage of up to one hundred layers, greatly improving the storage density of the optical disc. Furthermore, through the beam splitting multiplexing method, there is no need to add a servo light source separately. The present invention has a simple structure and is easy to operate. It effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0144] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A super-resolution three-dimensional optical storage focusing servo device, characterized in that: include: A light source shaping module, used for forming solid excitation light, hollow suppression light and solid servo light; A beam combining module, used for combining solid excitation light and hollow suppression light beam into a coaxial recording light with overlapping centers; A zoom layer selection module, used for controlling the axial position of the coaxial recording light focusing spot and the axial position of the solid servo light focusing spot; a servo signal detection module, configured to receive reflected servo light generated after the solid servo light is reflected by the servo guide layer, and convert the reflected servo light into a servo reflection signal for monitoring; A recording signal detection module, used for detecting the fluorescent signal generated by the coaxial recording light in the information recording layer; A driving control module, used for receiving the servo reflection signal and the fluorescence signal, and driving the beam combining module to perform aberration compensation on the solid excitation light and the hollow suppression light according to the fluorescence signal until the focus centers of the two are aligned; and driving the objective lens of the zoom layer selection module to move axially according to the servo reflection signal, so as to focus the solid servo light on the servo guide layer of the optical storage medium and focus the coaxial recording light on the selected information recording layer of the optical storage medium; The light source shaping module includes a light source unit and a shaping unit; the light source unit includes at least a laser light source of a single wavelength, or laser light sources of different wavelengths, emitting two incident laser beams into the shaping unit; the shaping unit performs beam splitting and shaping on the two incident laser beams, thereby generating a solid excitation light beam, a hollow suppression light beam and a solid servo light beam.

2. The focus servo device according to claim 1, characterized in that: The zoom layer selection module includes a recording objective lens and a servo objective lens. The recording objective lens is used to control the axial position of the coaxial recording light focusing spot, and the servo objective lens is used to control the axial position of the solid servo light focusing spot. The axial movement of the servo objective lens can link or trigger the recording objective lens to make corresponding axial movement in time; the drive control module drives the servo objective lens to move axially according to the servo reflection signal, and at the same time links or triggers the recording objective lens to move axially.

3. The focusing servo device according to claim 1 or 2, characterized in that: The numerical aperture of the objective lens of the zoom layer selection module is not less than 0.

65.

4. The focus servo device according to claim 2, characterized in that: The recording objective lens and the servo objective lens are rigidly connected.

5. The focus servo device according to claim 1, characterized in that: The shaping unit includes a beam splitter, a collimating lens group, and a phase plate. The beam splitter is used to split an incident laser beam into at least two light beams. The collimating lens group is used to collimate each light beam. The phase plate is used to phase modulate the collimated light beam to form a hollow suppression light. The beam combining module comprises a dichroic mirror, and the dichroic mirror is used to combine light beams from different paths into one light beam; The zoom layer selection module includes a compensation lens and an objective lens, wherein the compensation lens is used to adjust the focus of each light beam, and the objective lens is used to adjust the axial position of the focus spot of each light beam; The driving control module includes a displacement actuator and a controller, wherein the controller is used to receive signals and send instructions to the displacement actuator, and the displacement actuator drives the zoom layer selection module and / or the beam combining module to perform precise adjustments according to the instructions; The recording signal detection module includes a first filter and a first photodetector, wherein the first filter is used to filter out unnecessary light of a specific wavelength to ensure the purity of the fluorescent signal; and the first photodetector is used to detect the fluorescent signal after passing through the first filter; The servo signal detection module includes a second filter, an astigmatic lens and a second photodetector. The second filter is used to filter out unnecessary light of a specific wavelength from the reflected servo light. The astigmatic lens is used to modulate the reflected servo light so that when the coaxial recording light focusing spot is on the selected information recording layer or deviates from the selected information recording layer, the shape of the spot formed by the reflected servo light on the second photodetector is different. The second photodetector is used to detect the reflected servo light after passing through the second filter and the astigmatic lens and convert it into a servo reflection signal for monitoring.

6. The focus servo device according to claim 1, characterized in that: The light source unit comprises a first light source (101) and a second light source (102); The shaping unit comprises a first collimating lens (201), a second collimating lens (202), a beam splitter (203), a 1 / 2 wave plate (204), a first 1 / 4 wave plate (205), a phase plate (206), a first reflector (207), and a polarization beam splitter (208); The beam combining module comprises a first focusing lens (401), a first compensation lens (403), a first dichroic mirror (405), a second dichroic mirror (406), a second focusing lens (402), a second compensation lens (404), and a second reflecting mirror (407); The zoom layer selection module comprises a third focusing lens (501), a third compensation lens (503), a recording objective lens (505), a fourth focusing lens (502), a fourth compensation lens (504), a second 1 / 4 wave plate (506) and a servo objective lens (507); The drive control module comprises a controller (606), a first displacement actuator (601), a second displacement actuator (602), a third displacement actuator (603), a fourth displacement actuator (604), and a fifth displacement actuator (605); The servo signal detection module comprises a second filter (801), an astigmatic lens (802), a second optical fiber (803), and a second photodetector (804); The light beam output by the first light source (101) forms solid excitation light (301) after passing through the first collimating lens (201); The light beam output by the second light source (102) is incident on the beam splitter (203) via the second collimating lens (202) to form a first transmitted light and a second transmitted light; the first transmitted light is incident on the phase plate (206) via the 1 / 2 wave plate (204) and the first 1 / 4 wave plate (205) in sequence to form a hollow suppression light (302) in a first circular polarization state; the second transmitted light is incident on the polarization beam splitter (208) via the first reflector (207) to form a solid servo light (303) in a first linear polarization state; The solid excitation light (301) passes through the first focusing lens (401) and the first compensation lens (403) in sequence and is incident on the first dichroic mirror (405), is reflected by the first dichroic mirror (405) to form first reflected light, and then is incident on the second dichroic mirror (406), is transmitted through the second dichroic mirror (406) to form third transmitted light; The hollow suppression light (302) passes through the second focusing lens (402) and the second compensation lens (404) in sequence and is incident on the second dichroic mirror (406), and is reflected by the second dichroic mirror (406) to form second reflected light; The second reflected light and the third transmitted light are combined by the second dichroic mirror (406) and then reflected by the second reflector (407) to form third reflected light; The third reflected light passes through a third focusing lens (501), a third compensation lens (503), and a recording objective lens (505) in sequence, and is incident on the Mth information recording layer (002) of the optical storage medium, and excites a fluorescent signal in a focused area; The solid servo light (303) passes through a fourth focusing lens (502) and a fourth compensation lens (504) in sequence and is incident on a second quarter wave plate (506), becoming fourth transmitted light having a second circular polarization state; The fourth transmitted light is incident on the servo guide layer (004) of the optical storage medium via the servo objective lens (507), and is reflected by the servo guide layer (004) to form fourth reflected light having a third circular polarization state; The fourth reflected light is incident on the second 1 / 4 wave plate (506) via the servo objective lens (507), and is transformed into fifth transmitted light having a second linear polarization state via the second 1 / 4 wave plate (506); The fifth transmitted light passes through the fourth compensation lens (504) and the fourth focusing lens (502) in sequence and is incident on the polarization beam splitter (208), and is reflected by the polarization beam splitter (208) to form fifth reflected light; The fifth reflected light sequentially passes through the second filter (801), the astigmatic lens (802), and the second optical fiber (803) to reach the second photodetector (804), and is converted into a servo reflection signal by the second photodetector (804); The second photodetector (804) is connected to the controller (606); The second photodetector (804) monitors the servo reflection signal and sends it to the controller (606); The controller (606) controls the third displacement actuator (603) to drive the third compensation lens (503) to move axially, the fourth displacement actuator (604) to drive the fourth compensation lens (504) to move axially, and the fifth displacement actuator (605) to drive the recording objective lens (505) and the servo objective lens (507) to move axially in real time according to the received servo reflection signal.

7. The focus servo device according to claim 6, characterized in that: The recording signal control module comprises a first filter (701), a fifth focusing lens (702), a first optical fiber (703), and a first photodetector (704); After being collected by the recording objective lens (505), the fluorescent signal is incident on the second reflector (407) through the third compensation lens (503) and the third focusing lens (501) in sequence, and is reflected by the second reflector (407) to form sixth reflected light; The sixth reflected light passes through the second dichroic mirror (406), the first dichroic mirror (405), the first filter (701), the fifth focusing lens (702), and the first optical fiber (703) in sequence and reaches the first photodetector (704); The first optical filter (701) transmits the fluorescent signal and filters out the solid excitation light (301) and the hollow inhibition light (302); The first photodetector (704) is connected to the controller (606); The first photodetector (704) detects the fluorescence signal and sends it to the controller (606); The controller (606) controls the first displacement actuator (601) to drive the first compensation lens (403) to move along the axial direction, and the second displacement actuator (602) to drive the second compensation lens (404) to move along the axial direction, respectively, according to the received fluorescent signal.

8. The focus servo device according to claim 6, characterized in that: The first linear polarization state and the second linear polarization state are perpendicular to each other.

9. The focus servo device according to claim 1 or 2, characterized in that: It also includes a spindle motor, which is used to control the high-speed rotation of the optical storage medium; the drive control module controls the rotation speed of the spindle motor according to the received servo reflection signal or fluorescent signal.

10. A super-resolution three-dimensional optical storage focusing servo method based on the focusing servo device according to any one of claims 1 to 9, characterized in that: The following steps are involved: A light source shaping module is used to form solid excitation light, hollow suppression light and solid servo light; A beam combining module is used to combine solid excitation light and hollow suppressed light beam into coaxial recording light with overlapping centers; The coaxial recording light and the solid servo light are focused on the Mth information recording layer and the servo guide layer of the optical storage medium respectively by using a zoom layer selection module, where M is an integer; Using a servo signal detection module to monitor a servo reflection signal generated by the solid servo light being reflected by the servo guide layer and send the signal to a drive control module; If the servo reflection signal is not within the set range, the drive control module is used to drive the recording objective lens and the servo objective lens of the zoom layer selection module to move axially together according to the servo reflection signal until the servo reflection signal detected by the servo signal detection module is within the set range, thereby refocusing the solid servo light on the servo guide layer of the optical storage medium and refocusing the coaxial recording light on the Mth information recording layer of the optical storage medium; wherein the recording objective lens is used to control the axial position of the focusing spot of the coaxial recording light, and the servo objective lens is used to control the axial position of the focusing spot of the solid servo light; The recording signal detection module is used to detect the fluorescence signal generated by the coaxial recording light on the information recording layer and send it to the driving control module; if the focusing center positions of the solid excitation light and the hollow suppression light are offset, the driving control module drives the beam combining module to perform aberration compensation on the solid excitation light and the hollow suppression light according to the fluorescence signal until the focusing centers of the two are aligned; The fluorescence signal is used as a feedback signal to indicate whether there is an offset between the focus center positions of the solid excitation light and the hollow inhibition light.

11. The focusing servo method according to claim 10, characterized in that: The driving control module includes a controller, a first displacement actuator and a second displacement actuator; the controller controls the first displacement actuator to drive the first compensation lens of the beam combining module to move axially, and the second displacement actuator to drive the second compensation lens of the beam combining module to move axially according to the received fluorescence signal; The aberration compensation of the solid excitation light is achieved by the axial movement of the first compensation lens; and the aberration compensation of the hollow suppression light is achieved by the axial movement of the second compensation lens.

12. The focusing servo method according to claim 10, characterized in that: After receiving the zoom layer jump request, the driving control module drives the third compensation lens of the zoom layer selection module to move along the axial direction, and drives the recording objective lens and the servo objective lens to move along the axial direction together, so that the focus of the solid excitation light and the hollow suppression light moves to the Nth information recording layer; then drives the fourth compensation lens of the zoom layer selection module to move along the axial direction, so that the focus of the solid servo light is restored to the servo guide layer; Wherein, N is an integer and N≠M.

13. The focusing servo method according to claim 12, characterized in that: The driving control module includes a controller and a third displacement actuator, a fourth displacement actuator and a fifth displacement actuator; after receiving a zoom layer jump request, the controller outputs a preset constant bias voltage to the third displacement actuator, the fourth displacement actuator and the fifth displacement actuator respectively; the third displacement actuator drives the third compensation lens to move axially, and the fifth displacement actuator drives the recording objective lens and the servo objective lens to move axially together, so that the focus of the solid excitation light and the hollow suppression light moves to the Nth information recording layer; then the fourth displacement actuator drives the fourth compensation lens to move axially, so that the focus of the solid servo light is restored to the servo guide layer.

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