Super-resolution three-dimensional optical storage focusing servo apparatus and servo method

Abstract

The present invention provides a super-resolution three-dimensional optical storage focusing servo apparatus and servo method. The apparatus integrates a light source and shaping module, a beam combining module, a zoom-based layer selection module, a servo signal detection module, and a drive control module. Solid excitation light and hollow suppression light are combined to form coaxial recording light, a signal generated by a servo guide layer reflecting solid servo light is used to control a servo objective lens and a recording objective lens to move axially, and during reading and writing, the centers of two beams are always kept aligned, thereby achieving high-speed nanometer focusing servo. No additional servo light source is required, and the focuses of the two beams are adjusted in real time to keep three-dimensional alignment, exceeding the diffraction limit, thereby increasing the storage density. A lens group is used to compensate for aberration so as to achieve zoom-based layer switching, thereby achieving ultra-high density storage of a hundred layers. The apparatus has a simple structure, is convenient to operate, has good compatibility, is applied to the field of super-resolution three-dimensional optical storage, and has broad application prospects.

Description

A super-resolution three-dimensional optical storage focusing servo device and its servo method Technical Field

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

[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, the digital economy, and quantum computing, various emerging application scenarios are placing higher demands on the security, capacity, and efficiency of data storage. This is particularly true for industries such as military, law enforcement, archives, healthcare, and finance, where much sensitive data requires long-term or even permanent, tamper-proof preservation. Optical storage technology, with its non-contact, offline read / write principle, is characterized by security, reliability, ultra-low energy consumption, and long lifespan (>50 years), making it ideal for the long-term storage of massive amounts of data. However, traditional optical storage technology is limited by the optical diffraction limit and the reflection-based read / write mechanism, resulting in commercial Blu-ray discs having a single-disc storage capacity in the hundreds of gigabytes range and a maximum of three layers on a single side. This significantly hinders the widespread application of optical storage technology and related products in the big data market. To improve storage capacity, researchers at home and abroad have conducted numerous studies on multi-layer storage, multi-dimensional storage, multi-wavelength multi-level storage, and holographic storage. However, these technologies have not fundamentally broken through the diffraction limit. No matter which technology is used, it is impossible to achieve a true milestone breakthrough in storage capacity. Moreover, they are costly and difficult to industrialize on a large scale.

[0003] In recent years, researchers have been dedicated to developing super-resolution three-dimensional optical storage technologies that break through the optical diffraction limit. Among them, the dual-beam modulation focusing-induced emission super-resolution optical storage technology, based on the dual-beam super-resolution principle, introduces a second hollow suppression beam to modulate the effective range of the first solid excitation beam, building upon the traditional single-beam solid excitation light reading and writing. By utilizing the fluorescence contrast between the central and surrounding areas of the focal range, information is recorded, forming information recording points smaller than the diffraction limit, thereby achieving ultra-high-density storage. It can complete multi-layer recording of hundreds of layers, with a single disk capacity potentially on the order of Pb (see Nature, 2024, 626:772-778).

[0004] However, breaking the diffraction limit does not signify the full arrival of a new generation of optical storage technology. Many challenges remain on the road to industrialization. First, unlike traditional commercial optical storage devices, ultra-resolution 3D optical storage systems employ dual beams for information recording. One beam, a solid excitation beam, reacts with the material to form information points, while the other, a hollow suppression beam (with zero intensity at the center), prevents the formation of these points, ultimately resulting in nanoscale information points that break the diffraction limit. Therefore, both the solid excitation and hollow suppression beams must maintain three-dimensional alignment during both writing and reading processes. Existing focus servos only consider single-beam tracking compensation and are unsuitable for ultra-resolution 3D optical storage systems, necessitating the development of matching focus servo devices. Second, to achieve ultra-high-density multilayer storage, the recording medium of ultra-resolution 3D optical storage systems requires extremely high transparency. Furthermore, unlike traditional commercial optical storage systems that rely on reflected light for readout, ultra-resolution 3D optical storage systems utilize fluorescence readout. How to quickly position and zoom different layers during high-speed optical disc rotation, and other related issues, place stringent demands on the focus servo control system of ultra-resolution 3D optical storage systems. Existing servo solutions for super-resolution 3D optical storage systems all introduce separate servo beams, such as CN109524029B. Combined with the dual beams for reading and writing, the entire optical path system requires three lasers of different wavelengths, each needing separate control. This makes the system complex and difficult to integrate. Furthermore, the focusing servo system cannot monitor and compensate for the center positions of the solid excitation beam and the hollow suppression beam to restore alignment. Once the focus of the dual beams deviates beyond a certain range (typically tens of nanometers), super-resolution recording cannot be achieved, and the servo system becomes meaningless. Therefore, there is an urgent need to develop a high-precision, simple, and highly integrated focusing servo device and its servo control method for super-resolution 3D optical storage. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to propose a super-resolution three-dimensional optical storage focusing servo device and its servo method, which can accurately execute multi-layer focusing servoing during the reading and writing process of super-resolution three-dimensional optical storage media.

[0006] To achieve the above and other related objectives, the present invention provides a super-resolution three-dimensional optical storage focusing servo device, comprising: a light source shaping module for forming a solid excitation light, a hollow suppression light, and a solid servo light; a beam combining module for combining the solid excitation light and the hollow suppression light into a coaxial recording light with the center coincident; a zoom layer selection module for controlling the axial position of the focused spot of the coaxial recording light and the axial position of the focused spot of the solid servo light; a servo signal detection module for receiving the reflected servo light generated after the solid servo light is reflected by the servo guiding layer, and converting it into a servo reflection signal for monitoring; and a recording signal detection module for detecting the fluorescence signal generated by the coaxial recording light on the information recording layer.

[0007] The drive control module is used to receive the servo reflection signal and the fluorescence signal, 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 their focus centers are aligned; and drive the objective lens of the zoom layer selection module to move along the axis according to the servo reflection signal, so as to focus the solid servo light on the servo guiding 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 a corresponding axial movement in a timely manner. The drive control module drives the servo objective lens to move along the axial direction according to the servo reflection signal, and simultaneously links or triggers the recording objective lens to move along the axial direction.

[0009] Preferably, the recording objective and the servo objective are rigidly connected to maintain their relative position stability, thereby achieving more precise focusing and tracking servoing.

[0010] Furthermore, the connection between the recording objective and the servo objective is not limited to a rigid connection. As long as the recording objective can make corresponding axial movements in a timely manner according to the movement of the servo objective to achieve the function of focusing and tracking servo, other forms of connection or non-connection synchronous motion 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 this invention, "axial direction" refers to the direction of the optical axis.

[0013] The optical storage medium has a multilayer structure, including multiple information recording layers and a servo guiding layer with spiral grooves. Preferably, the information recording layer comprises a photoinitiator, monomers, metal ion compounds, and aggregation-induced emission 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, which is then split by the shaping unit to generate a solid excitation light, a hollow suppression light, and a solid servo light. Preferably, the light source unit includes at least a single-wavelength laser source or laser sources of different wavelengths, emitting two incident laser beams that enter the shaping unit. The shaping unit splits and shapes the two incident laser beams to generate a solid excitation light, a hollow suppression light, and a 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 source as the solid excitation light, or shares the same laser source as 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 beams. The collimating lens group is used to collimate each beam. The phase plate is used to perform phase modulation on the collimated beam to form a hollow suppression light.

[0017] The beam combining module includes a dichroic mirror, which is used to combine beams from different paths into a single beam.

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

[0019] The drive control module includes a displacement actuator and a controller. The controller is used to receive signals and send instructions to the displacement actuator. The displacement actuator drives the zoom layer selection module and / or the beam combining module to make precise adjustments according to the instructions.

[0020] The recorded signal detection module includes a first filter and a first photodetector. The first filter is used to filter out unwanted light of specific wavelengths to ensure the purity of the fluorescence signal; the first photodetector is used to detect the fluorescence 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 unwanted specific wavelengths of light from the reflected servo light. The astigmatic lens is used to modulate the reflected servo light so that when the coaxial recording light is focused on or off the selected information recording layer, the shape of the light 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 half-wave plate, a first quarter-wave plate, a phase plate, a first reflecting mirror, and a polarizing beam splitter; the beam combining module includes a first focusing lens, a first compensating lens, a first dichroic mirror, a second dichroic mirror, a second focusing lens, a second compensating lens, and a second reflecting mirror; the zoom layer selection module includes a third focusing lens, a third compensating lens, a recording objective lens, a fourth focusing lens, a fourth compensating lens, a second quarter-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, and a fourth displacement actuator. The fifth displacement actuator; the servo signal detection module includes a second filter, an astigmatic lens, a second optical fiber, and a second photodetector; the beam output from the first light source passes through a first collimating lens to form a solid excitation beam; the beam output from the second light source passes through a second collimating lens and enters a beam splitter to form a first transmitted beam and a second transmitted beam; the first transmitted beam passes through a half-wave plate and a first quarter-wave plate sequentially and enters a phase plate to form a hollow suppressed beam with a first circular polarization state; the second transmitted beam passes through a first reflecting mirror and enters a polarizing beam splitter, and is transmitted through the polarizing beam splitter to form a solid servo beam with a first linear polarization state; the solid excitation beam passes through a first focusing lens and a first compensating lens sequentially and enters a first dichroic mirror, and is reflected by the first dichroic mirror to form a second... The reflected light then enters the second dichroic mirror, and is transmitted through the second dichroic mirror to form the third transmitted light; the hollow suppression light sequentially passes through the second focusing lens and the second compensating lens and enters the second dichroic mirror, and is reflected by the second dichroic mirror to form the second reflected light; the second reflected light and the third transmitted light are combined by the second dichroic mirror and reflected by the second reflecting mirror to form the third reflected light; the third reflected light sequentially passes through the third focusing lens, the third compensating lens, and the recording objective lens and enters the Mth information recording layer of the optical storage medium, exciting a fluorescence signal in the focusing region; the solid servo light sequentially passes through the fourth focusing lens and the fourth compensating lens and enters the second 1 / 4 waveplate, becoming the fourth transmitted light with the second circular polarization state; the fourth Transmitted light is incident on the servo guiding layer of the optical storage medium via a servo objective lens, and is reflected by the servo guiding layer to form a fourth reflected light with a third circular polarization state. The fourth reflected light is incident on the second quarter-wave plate via the servo objective lens, and is transformed into a fifth transmitted light with a second linear polarization state by the second quarter-wave plate. The fifth transmitted light is incident on a polarizing beam splitter via a fourth compensating lens and a fourth focusing lens, and is reflected by the polarizing beam splitter to form a fifth reflected light. The fifth reflected light is incident on a second photodetector via a second filter, an astigmatic lens, and a second optical fiber, and is converted into a servo reflection signal by the second photodetector. The second photodetector is connected to a controller; the second photodetector monitors the servo reflection signal and sends it to the controller.The controller, based on the received servo reflection signal, controls in real time the third displacement actuator to drive the third compensating lens to move axially, the fourth displacement actuator to drive the fourth compensating lens to move axially, and the fifth displacement actuator to drive the recording objective and the servo objective to move axially together.

[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; the fluorescence signal, after being collected by the recording objective lens, is sequentially incident on the second reflecting mirror through the third compensating lens and the third focusing lens, and is reflected by the second reflecting mirror to form a sixth reflected light; the sixth reflected light sequentially passes through the second dichroic mirror, the first dichroic mirror, the first filter, the fifth focusing lens, and the first optical fiber to reach the first photodetector; the first filter transmits the fluorescence signal, filtering out solid excitation light and hollow suppression light; the first photodetector is connected to a controller; the first photodetector detects the fluorescence signal and sends it to the controller; the controller, based on the received fluorescence signal, controls the first displacement actuator to drive the first compensating lens to move axially, and the second displacement actuator to drive the second compensating lens to move axially.

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

[0025] Furthermore, the focusing servo device 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 fluorescence signal.

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

[0027] Solid excitation light, hollow suppression light, and solid servo light are formed using a light source shaping module;

[0028] The solid excitation beam and the hollow suppression beam are combined into a coaxial recording beam with the center coincident by a beam combining module;

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

[0030] The servo signal detection module monitors the servo reflection signal generated by the reflection of solid servo light by the servo guiding layer and sends it to the drive control module.

[0031] If the servo reflection signal is not within the set range, the drive control module drives the recording objective and servo objective of the zoom layer selection module to move together along the axial direction according to the servo reflection signal until the servo reflection signal detected by the servo signal detection module is within the set range. This achieves the refocusing of the solid servo light onto the servo guiding layer of the optical storage medium and the refocusing of the coaxial recording light onto the Mth information recording layer of the optical storage medium. The recording objective is used to control the axial position of the coaxial recording light focusing spot, and the servo objective is used to control the axial position of the solid servo light focusing spot.

[0032] The recording signal detection module detects the fluorescence signal generated by the coaxial recording light on the information recording layer and sends it to the drive control module. If there is a shift in the focal center positions of the solid excitation light and the hollow suppression light, 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 fluorescence signal until their focal centers are aligned. The fluorescence signal serves as a feedback signal to indicate whether there is a shift in the focal 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, based on the received fluorescence signal, 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. The axial movement of the first compensation lens achieves aberration compensation for solid excitation light, and the axial movement of the second compensation lens achieves aberration compensation for hollow suppression light.

[0034] According to a specific embodiment of the present invention, after receiving a zoom layer skipping request, the drive control module drives the third compensation lens of the zoom layer selection module to move along the axial direction, and drives the recording objective and the servo objective to move together along the axial direction, so that the focal points of the solid excitation light and the hollow suppression light are moved to the Nth information recording layer; then, it drives the fourth compensation lens of the zoom layer selection module to move along the axial direction, so that the focal point of the solid servo light is restored to the servo guiding 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, fourth, and fifth displacement actuators. After receiving a zoom layer jump request, the controller outputs a pre-set constant bias voltage to the third, fourth, and fifth displacement actuators respectively. The third displacement actuator drives the third compensation lens to move axially, and the fifth displacement actuator drives the recording objective and the servo objective to move axially together, so that the focal points of the solid excitation light and the hollow suppression light are moved to the Nth information recording layer. Then, the fourth displacement actuator drives the fourth compensation lens to move axially, so that the focal point of the solid servo light is restored to the servo guiding layer.

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

[0037] (1) During the reading and writing process, the focus of solid excitation light and hollow suppression light can be adjusted in real time by using servo reflection signal and fluorescence signal to control the focus, and always keep the two beams three-dimensional aligned and focused on the selected information recording layer, thereby realizing the recording of nano-information points that exceed the optical diffraction limit, which greatly improves the storage density of optical discs.

[0038] (2) By combining lens group to compensate for aberrations, zoom layer skipping can ultimately achieve ultra-high density three-dimensional data storage with 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 require the addition of a separate servo light source, and can complete high-speed nano-focusing servoing on the basis of a dual-beam read-write system;

[0040] (4) The present invention has a simple structure, is easy to operate, and is compatible with other servo control systems such as tracking servo, speed servo, tilt servo, etc. Attached Figure Description

[0041] Figure 1 shows a schematic diagram of the overall architecture of a super-resolution three-dimensional optical storage focusing servo device proposed in this invention.

[0042] Figure 2 shows a schematic diagram of a specific embodiment of the focusing servo device of the present invention;

[0043] Figure 3 shows a schematic diagram of the focused spot of coaxial recording light and solid servo light during the zoom-skipping process of the present invention;

[0044] Figure 4 shows a flowchart of a super-resolution three-dimensional optical storage zoom skipping method according to the present invention;

[0045] Figure 5 shows a flowchart of a super-resolution three-dimensional optical storage focusing servo method according to the present invention.

[0046] Component Labeling Description: 001 Super-resolution Optical Disc; 002 Mth Information Recording Layer; 003 Nth Information Recording Layer; 004 Servo Guiding Layer; 10 Light Source Shaping Module; 100 Light Source Unit; 101 First Light Source; 102 Second Light Source; 200 Shaping Unit; 201 First Collimating Lens; 202 Second Collimating Lens; 203 Beam Splitter; 204 Half-wave Plate; 205 First Quarter-wave Plate; 206 Phase Plate; 207 First Reflector; 208 Polarizing Beam Splitter; 301 Solid Excitation Beam; 302 Hollow Suppression Beam; 303 Solid Servo Beam; 40 Beam Combining Module; 401 First Focusing Lens; 402 Second Focusing Lens; 403 First Compensation Lens; 404 Second Compensation Lens; 405 First Dichroic Mirror; 406 Second Dichroic Mirror; 407 Second Reflector; 50 Zoom Selection Layer Module; 501 Third Focusing Lens; 502 Fourth Focusing Lens; 503 Third Compensation Lens; 504Fourth compensating lens 505; Recording objective lens 506; Second 1 / 4 wave plate 507; Servo objective lens 60; Drive control module 601; First displacement actuator 602; Second displacement actuator 603; Third displacement actuator 604; Fourth displacement actuator 605; Fifth displacement actuator 606; Controller 607; Spindle motor 70; Recording signal detection module 701; First filter 702; Fifth focusing lens 703; First optical fiber 704; First photodetector 80; Servo signal detection module 801; Second filter 802; Astigmatic lens 803; Second optical fiber 804; Second photodetector. Detailed Implementation

[0047] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0048] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0049] The following is a further detailed explanation with reference to the accompanying drawings.

[0050] In the following specific implementation, an ultra-resolution optical disc is selected as the ultra-resolution three-dimensional optical storage medium.

[0051] The overall architecture of the super-resolution three-dimensional optical storage focusing servo device proposed in this invention is shown in Figure 1. This device is suitable for super-resolution three-dimensional optical storage media. The entire device consists of six main modules: 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.

[0052] The light source shaping module 10 includes a light source unit 100 and a shaping unit 200.

[0053] The super-resolution three-dimensional optical storage focusing servo device proposed in this invention can be applied to various optical storage systems based on the dual-beam super-resolution principle, such as stimulated emission loss principle, edge light suppression principle, triplet-triplet absorption principle, etc. The wavelength of the dual beams used for recording is selected according to the principle and material properties. Therefore, the light source unit 100 includes at least one wavelength laser light source, or laser light sources of different wavelengths, emitting two incident laser beams into the shaping unit 200;

[0054] The shaping unit 200 includes at least a beam splitter, a collimating lens group, and a phase plate. Its function is to split and shape two incident laser beams to generate a solid excitation beam 301, a hollow suppression beam 302, and a solid servo beam 303. The solid servo beam 303 has the same wavelength as either the solid excitation beam 301 or the hollow suppression beam 302, meaning that the solid servo beam 303 shares the same laser source as the solid excitation beam 301, or the solid servo beam 303 shares the same laser source as the hollow suppression beam 302.

[0055] The beam combining module 40 includes at least a dichroic mirror for combining the solid excitation light 301 and the hollow suppression light 302 into the zoom layer selection module 50.

[0056] The zoom selection module 50 includes at least a compensation lens and an objective lens, used to control the axial position of the focused spot;

[0057] The drive control module 60 includes at least a displacement actuator and a controller, which drives the zoom layer selection module 50 to move, focusing 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, while focusing the solid servo light 303 on the servo guide layer of the super-resolution optical disc 001.

[0058] The recording signal detection module 70 includes at least a filter and a photodetector, and detects the fluorescence signals generated by the solid excitation light 301 and the hollow suppression light 302 on the information recording layer.

[0059] The servo signal detection module 80 includes at least a filter, an astigmatic lens, and a photodetector, and monitors the servo reflection signal generated by the reflection of the solid servo light 303 by the servo guiding layer.

[0060] The modules are connected to each other via optical or electrical signals. The light source unit 100 contains two light sources, each emitting a laser beam. After passing through the shaping unit 200, three laser beams are obtained: a solid excitation beam 301, a hollow suppression beam 302, and a solid servo beam 303. Solid excitation light 301 and hollow suppression light 302 are coupled through beam combining module 40 into zoom layer selection module 50, and focused onto the selected information recording layer of super-resolution optical disc 001. They interact with the medium of the recording layer to generate a fluorescence signal. The fluorescence signal is detected by recording signal detection module 70 through zoom layer selection module 50, and the detection result is transmitted to drive control module 60. Meanwhile, solid servo light 303 is focused by zoom layer selection module 50 onto servo guide layer of super-resolution optical disc. After reflection, it passes through zoom layer selection module 50 again and is then detected by servo signal detection module 80, which transmits the detection result to drive control module 60. Drive control module 60 calculates and issues commands based on the detection results to control beam combining module 40 and zoom layer selection module 50 to achieve focus servo control.

[0061] Furthermore, since the super-resolution three-dimensional optical storage system includes both write and read functions, when the write 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 read 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, this 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.

[0062] Figure 2 illustrates a specific embodiment of the focusing servo device of the present invention. As shown in Figure 2, the super-resolution optical disc for reading and writing has a multi-layer structure, including a recording layer and a servo guiding layer located below the recording layer. The recording layer is an aggregation-induced emission dye-doped photoresist with a thickness greater than 100 μm, which can be modulated with dual beams to generate nano-information dots that break through the optical diffraction limit and emit fluorescence, and has high transparency and high uniformity. To achieve ultra-high density multi-layer storage, the recording layer is designed to contain multiple information recording layers (e.g., the Mth information recording layer 002, the Nth information recording layer 003), while the bottom layer of the super-resolution optical disc 001 has a spiral groove-shaped servo guiding layer 004, the surface of which is coated with a reflective material.

[0063] For writing information to a super-resolution optical disc, two light sources with wavelengths of λ1 and λ2 are used. The laser with wavelength λ1 will produce a photopolymerization effect in the focal area of ​​the recording layer, while the laser with wavelength λ2 will suppress the photopolymerization effect in the focal area of ​​the recording layer.

[0064] Laser emitted from the first light source 101 at wavelength λ1 passes through the first collimating lens 201 to form solid excitation light; laser emitted from the second light source 102 at wavelength λ2 passes through the second collimating lens 202 and the beam splitter 203 to form first transmitted light and second transmitted light. The first transmitted light passes through the half-wave plate 204, the first quarter-wave plate 205 and the phase plate 206 to form a circularly polarized hollow suppression light with zero central intensity. The second transmitted light passes through the first reflecting mirror 207 and the polarizing beam splitter 208 to form a solid servo light with linear polarization (s-polarization).

[0065] The first dichroic mirror 405 reflects λ1, and the second dichroic mirror 406 reflects λ2 and transmits λ1. Therefore, the solid excitation light and the hollow suppression light are coupled into a single optical path. The first focusing lens 401 and the first compensation lens 403 jointly compensate for the aberration of the solid excitation light, and the second focusing lens 402 and the second compensation lens 404 jointly compensate for the aberration of the hollow suppression light. This ensures 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.

[0066] The coaxial recording light, composed of solid excitation light and hollow suppression light, is reflected by the second mirror 407. Then, the third focusing lens 501 and the third compensation lens 503 together compensate for the aberration of the coaxial recording light, so that after passing through the recording objective lens 505, it is focused onto the M information recording layer 002 of the super-resolution optical disc 001, forming nano-information dots within the exposure time, and completing the writing of information.

[0067] During the writing process of a super-resolution optical disc, errors such as disc jitter and eccentricity caused by high-speed rotation and external environmental vibrations can cause the focusing centers of the solid excitation light and the hollow suppression light to deviate from the recording layer, easily leading to erroneous writing or even loss of information. Therefore, a nanometer-precision focusing servo is required. The fourth focusing lens 502 and the fourth compensation lens 504 jointly compensate for the aberrations of the s-polarized solid servo light, so that after passing through the second quarter-wave plate 506 and the servo objective lens 507, the light is focused onto the servo guiding layer 004 below the super-resolution optical disc 001. The servo guiding layer 004 has high reflectivity for the solid servo light. After reflection, it passes through the second quarter-wave plate 506, at which point the reflected servo light becomes p-polarized light. Therefore, when passing through the polarization beam splitter 208, it is separated from the emitted servo light. After the stray light is filtered out by the second filter 801, it is focused onto the recording layer by the astigmatic lens 802. The light signal is collected in the second optical fiber 803 by the second photodetector 804. The second photodetector 804 is 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 to the controller 606. The controller 606 adjusts the fifth displacement actuator 605 (which 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 achieve focusing tracking servo.

[0068] For information readout from the super-resolution optical disc, to maintain long-term information reliability, two additional light sources with wavelengths of λ3 and λ4 are used. The λ3 wavelength laser, when focused on the nano-information dots, produces aggregation-induced emission, enhancing fluorescence intensity. Conversely, the λ4 wavelength laser, when focused on the nano-information dots, suppresses aggregation-induced emission. Neither λ3 nor λ4 wavelength lasers produce fluorescence or only weak fluorescence in unwritten areas. The readout optical path is essentially the same as the write setup. When the solid excitation light of wavelength λ3 and the hollow suppression light of wavelength λ4 are focused onto the M-th information recording layer 002 of the super-resolution optical disc 001 after passing through the recording objective lens 505, a strong fluorescence signal is emitted when the information recording dot area is illuminated due to the aggregation-induced emission effect. This 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. Since both the second dichroic mirror 406 and the first dichroic mirror 405 transmit the fluorescence signal, they reflect the hollow suppression light of wavelength λ4 and the λ3 wavelength light, respectively. The solid excitation light separates the fluorescence signal from the solid excitation light and the hollow suppression light. After being 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 acts as a pinhole, ensuring that the incident end face of the optical fiber is confocal with the system's focal point. This means that only the fluorescence / reflected light emitted at the system's focal point reaches the first photodetector 704, while other illuminated areas are not blocked at the focal point, enhancing the signal-to-noise ratio and avoiding crosstalk between adjacent recording points, thus completing the information readout. Furthermore, during the readout process, the focus tracking servo remains operational to ensure accurate information readout.

[0069] During the reading / writing process of the optical disc, a spindle motor 607 is used to control the high-speed rotation of the optical disc. The controller 606 controls the speed of the spindle motor 607 based on the received servo reflection signal or fluorescence signal to make the signal transmission more stable and further ensure the accuracy of the focus servo.

[0070] Figure 3 shows a schematic diagram of the focused spot of the coaxial recording light and the solid servo light during the zoom-skipping process. First, based on the geometrical optical relationships of the first compensation lens 403, the second compensation lens 404, the third compensation lens 503 and the recording objective lens 505, the fourth compensation lens 504 and the servo objective lens 507 in Figure 2, Newton's formula and scanning calibration tests can be applied to calculate and pre-store the correspondence between the displacement and focus movement of each compensation lens and objective lens.

[0071] When reading / writing the Mth information recording layer 002, the coaxial recording light composed of solid excitation light and 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, exciting a fluorescence signal that breaks the diffraction limit, which is collected by the first photodetector 704 and converted into a recording signal; the solid servo light is focused by the servo objective lens 507 onto the servo guiding layer 004 below the super-resolution optical disc 001, and the reflected light signal is collected by the second photodetector 804 and converted into a servo reflection signal. The first photodetector 704 and the second photodetector 804 are connected to the controller 606, which contains a control algorithm. By analyzing the algorithm, the focusing center positions of the solid excitation light and the hollow suppression light can be calculated. When the centers of the two are found to be misaligned, the controller 606 controls the first displacement actuator 601 to drive the first compensation lens 403 to move axially, and the second displacement actuator 602 to drive the second compensation lens 404 to move axially, based on the received fluorescence signal. Aberration compensation for the solid excitation light is achieved by the axial movement of the first compensation lens 403; aberration compensation for the hollow suppression light is achieved 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, disc jitter, warping, etc., may cause the focus spot of the coaxial recording light and the solid servo light to deviate. The controller 606 will monitor the servo reflection signal in real time and output a focus error compensation signal command to control the fifth displacement actuator 605, which will drive the recording objective lens 505 and the servo objective lens 507 to move axially together, so that the focus error is reduced to 0, realizing focus tracking servo on the Mth information recording layer 002.

[0072] After the controller 606 receives a request to zoom to the Nth information recording layer 003, it applies an additional constant bias voltage to the fifth displacement actuator 605 while receiving a focus error compensation signal. This moves the focus of the coaxial recording light to the Nth information recording layer 003. Simultaneously, the third displacement actuator 603 and the fourth displacement actuator 604 are each applied a constant bias voltage, causing the third compensation lens 503 and the fourth compensation lens 504 to move axially, compensating for aberrations. This allows the recovered solid servo light to be focused by the servo objective lens 507 onto the servo guide layer 004 below the super-resolution optical disc 001. The controller 606 continuously monitors the focus center positions of the solid excitation light and the hollow suppression light, as well as the servo reflection signal, repeating the above process. Furthermore, when writing information, not only is the user data recorded on the super-resolution optical disc 001, but the location of this data within the super-resolution optical disc 001, including layer information and sector information, is also recorded, so that the required data can be quickly located on the super-resolution optical disc 001 during retrieval.

[0073] Figure 4 shows a flowchart of the super-resolution three-dimensional optical storage zoom-skipping method of the present invention. It mainly includes the following steps:

[0074] Step 1: The light source unit emits laser light, which is then split by the shaping unit to generate solid excitation light, hollow suppression light, and solid servo light;

[0075] Step 2: After coupling, the solid excitation light and the hollow suppression light are focused together on the Mth information recording layer of the optical disc, and the solid servo light is focused on the servo boot layer of the optical disc;

[0076] Step 3: The controller monitors the focusing center positions of the solid excitation beam and the hollow suppression beam. If there is a deviation, the controller drives the first compensation lens and the second compensation lens to perform aberration compensation for the solid excitation beam and the hollow suppression beam respectively until their focusing centers are aligned.

[0077] Step 4: After receiving the zoom jump request, the controller outputs a pre-set constant bias voltage to the third, fourth and fifth displacement actuators respectively.

[0078] Step 5: The third displacement actuator drives the third compensation lens to move along the axial direction, and the fifth displacement actuator drives the recording objective and the servo objective to move together along the axial direction, so that the focal point of the solid excitation light and the hollow suppression light is moved to the Nth information recording layer.

[0079] Step 6: The fourth displacement actuator drives the fourth compensation lens to move along the axial direction, 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;

[0080] By following the steps above, zoom jump from the Mth information recording layer to the Nth information recording layer is completed. Repeat steps 1 to 6 to achieve multi-layer recording.

[0081] Figure 5 shows a flowchart of a super-resolution three-dimensional optical storage focusing servo method according to the present invention. It mainly includes the following steps:

[0082] Step 1: The light source unit emits laser light, which is then split by the shaping unit to generate solid excitation light, hollow suppression light, and solid servo light;

[0083] Step 2: After the solid excitation light and the hollow suppression light are coupled, they are focused onto the selected information recording layer through the recording objective lens, and the solid servo light is focused onto the servo guiding layer through the servo objective lens;

[0084] Step 3: The servo signal detection module detects the reflected servo light of the solid servo light, thereby obtaining the focusing error and sending the detection result of the focusing error to the controller;

[0085] Step 4: The controller controls the fifth displacement actuator to drive the recording objective and the servo objective to move together along the axial direction according to the detection results until the focusing error is within the set range;

[0086] Step 5: During the high-speed rotation of the optical disc, the recording signal detection module detects the fluorescence signal generated on the information recording layer after the solid excitation light and the hollow suppression light are coupled and sends it to the controller; if there is a shift in the focus center position of the solid excitation light and the hollow suppression light, 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 their focus centers are aligned.

[0087] The fluorescence signal serves as a feedback signal, used to indicate whether there is a shift in the focal center position between the solid excitation light and the hollow suppression light.

[0088] Through the above operations, during the high-speed rotation of the optical disc, the focus centers of the solid excitation light and the hollow suppression light are aligned and maintained on the selected information recording layer, thus completing the focus servo.

[0089] In summary, the super-resolution three-dimensional optical storage focusing servo device and its servo method of the present invention utilize the servo reflection signal reflected by a servo guiding layer to control the axial movement of the objective lens. Combined with a lens group aberration compensation method, zoom layer skipping is achieved. Furthermore, during the read / write process, the focus of the solid excitation light and the hollow suppression light can be adjusted in real time to maintain dual-beam three-dimensional alignment, thereby accurately achieving ultra-high density three-dimensional data optical storage of up to hundreds of layers, greatly improving the storage density of optical discs. Moreover, through beam multiplexing, a separate servo light source is unnecessary. The present invention has a simple structure, is easy to operate, and effectively overcomes various shortcomings of the prior art, thus possessing high industrial application value.

[0090] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should 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: The light source shaping module is used to form solid excitation light, hollow suppression light, and solid servo light; The beam combining module is used to combine solid excitation light and hollow suppression light into a coaxial recording light with the center coinciding; The zoom layer selection module is used to control the axial position of the coaxial recording light focusing spot and the axial position of the solid servo light focusing spot; The servo signal detection module is used to receive the reflected servo light generated after the solid servo light is reflected by the servo guiding layer, and convert it into a servo reflection signal for monitoring. A recording signal detection module is used to detect the fluorescence signal generated by the coaxial recording light on the information recording layer; The 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 focus centers of the two are aligned. The objective lens of the zoom layer selection module is driven to move along the axis according to the servo reflection signal, so as to focus the solid servo light on the servo guiding 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 single-wavelength laser light source, or laser light sources of different wavelengths, which emit two incident laser beams into the shaping unit; the shaping unit splits and shapes the two incident laser beams to generate a solid excitation beam, a hollow suppression beam, and a solid servo beam.

2. The focusing servo device according to claim 1, characterized in that, The zoom layer selection module includes a recording objective and a servo objective. The recording objective is used to control the axial position of the coaxial recording light focusing spot, and the servo objective is used to control the axial position of the solid servo light focusing spot. The axial movement of the servo objective can link or trigger the recording objective to make a corresponding axial movement in a timely manner. The drive control module drives the servo objective to move along the axial direction according to the servo reflection signal, and simultaneously links or triggers the recording objective to move along the axial direction.

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 focusing servo device according to claim 2, characterized in that, The recording objective and the servo objective are rigidly connected.

5. The focusing 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 beams. The collimating lens group is used to collimate each beam. The phase plate is used to perform phase modulation on the collimated beam to form a hollow suppression light. The beam combining module includes a dichroic mirror, which is used to combine beams from different paths into a single beam. The zoom layer selection module includes a compensation lens and an objective lens. The compensation lens is used to adjust the focus of each beam, and the objective lens is used to adjust the axial position of the focused spot of each beam. The drive control module includes a displacement actuator and a controller. The controller is used to receive signals and send instructions to the displacement actuator. The displacement actuator drives the zoom layer selection module and / or the beam combining module to make precise adjustments according to the instructions. The recorded signal detection module includes a first filter and a first photodetector. The first filter is used to filter out unwanted light of specific wavelengths to ensure the purity of the fluorescence signal; the first photodetector is used to detect the fluorescence 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 unwanted specific wavelengths of light from the reflected servo light. The astigmatic lens is used to modulate the reflected servo light so that when the coaxial recording light is focused on or off the selected information recording layer, the shape of the light 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 focusing servo device according to claim 1, characterized in that, The light source unit includes a first light source (101) and a second light source (102); The shaping unit includes a first collimating lens (201), a second collimating lens (202), a beam splitter (203), a half-wave plate (204), a first quarter-wave plate (205), a phase plate (206), a first reflecting mirror (207), and a polarizing beam splitter (208); The beam combining module includes 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 includes 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 quarter wave plate (506), and a servo objective lens (507). The drive control module includes 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 includes a second filter (801), an astigmatic lens (802), a second optical fiber (803), and a second photodetector (804); The beam output from the first light source (101) is transformed into a solid excitation beam (301) after passing through the first collimating lens (201); The beam output from the second light source (102) is incident on the beam splitter (203) through 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) through the 1 / 2 wave plate (204) and the first 1 / 4 wave plate (205) in sequence to form a hollow suppressed light (302) with a first circular polarization state. The second transmitted light is incident on the polarization beam splitter (208) through the first reflecting mirror (207) and is transmitted through the polarization beam splitter (208) to form a solid servo light (303) with 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 enters the first dichroic mirror (405). After being reflected by the first dichroic mirror (405) to form the first reflected light, it enters the second dichroic mirror (406) and is transmitted through the second dichroic mirror (406) to form the third transmitted light. The hollow suppression light (302) passes through the second focusing lens (402) and the second compensation lens (404) in sequence and enters the second dichroic mirror (406), and is reflected by the second dichroic mirror (406) to form the 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 reflecting mirror (407) to form the third reflected light; The third reflected light passes sequentially through the third focusing lens (501), the third compensation lens (503), and the recording objective lens (505) and is incident on the Mth information recording layer (002) of the optical storage medium, where a fluorescence signal is generated in the focusing area. The solid servo light (303) passes through the fourth focusing lens (502) and the fourth compensation lens (504) in sequence and is incident on the second 1 / 4 wave plate (506), becoming the fourth transmitted light with the second circular polarization state; The fourth transmitted light is incident on the servo guiding layer (004) of the optical storage medium through the servo objective lens (507), and is reflected by the servo guiding layer (004) to form a fourth reflected light with a third circular polarization state; The fourth reflected light is incident on the second quarter-wave plate (506) through the servo objective lens (507), and becomes the fifth transmitted light with a second linear polarization state through the second quarter-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 polarizing beam splitter (208), and is reflected by the polarizing beam splitter (208) to form the fifth reflected light; The fifth reflected light passes sequentially through the second filter (801), the astigmatic lens (802), and the second optical fiber (803) to reach the second photodetector (804), where it is converted into a servo reflection signal. 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 along the axial direction in real time according to the received servo reflection signal, the fourth displacement actuator (604) to drive the fourth compensation lens (504) to move along the axial direction, and the fifth displacement actuator (605) to drive the recording objective lens (505) and the servo objective lens (507) to move together along the axial direction.

7. The focusing servo device according to claim 6, characterized in that, The recording signal control module includes a first filter (701), a fifth focusing lens (702), a first optical fiber (703), and a first photodetector (704); The fluorescence signal is collected by the recording objective (505) and then incident on the second reflecting mirror (407) through the third compensation lens (503) and the third focusing lens (501) in sequence. The second reflecting mirror (407) reflects the signal to form the sixth reflected light. The sixth reflected light passes sequentially 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) to reach the first photodetector (704); The first filter (701) transmits the fluorescence signal and filters out the solid excitation light (301) and the hollow suppression 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 according to the received fluorescence signal, and the second displacement actuator (602) to drive the second compensation lens (404) to move along the axial direction.

8. The focusing 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 focusing 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 speed of the spindle motor according to the received servo reflection signal or fluorescence signal.

10. A super-resolution three-dimensional optical storage focusing servo method based on the focusing servo device according to any one of claims 1-9, characterized in that, Includes the following steps: Solid excitation light, hollow suppression light, and solid servo light are formed using a light source shaping module; The solid excitation beam and the hollow suppression beam are combined into a coaxial recording beam with the center coincident by a beam combining module; The coaxial recording light and the solid servo light are focused onto the Mth information recording layer and the servo guiding layer of the optical storage medium, respectively, using a zoom layer selection module, where M is an integer. The servo signal detection module monitors the servo reflection signal generated by the reflection of solid servo light by the servo guiding layer and sends it to the drive control module. If the servo reflection signal is not within the set range, the drive control module drives the recording objective and servo objective of the zoom layer selection module to move together along the axial direction according to the servo reflection signal until the servo reflection signal detected by the servo signal detection module is within the set range. This achieves the refocusing of the solid servo light onto the servo guiding layer of the optical storage medium and the refocusing of the coaxial recording light onto the Mth information recording layer of the optical storage medium. The recording objective is used to control the axial position of the coaxial recording light focusing spot, and the servo objective is used to control the axial position of the solid servo light focusing spot. The recording signal detection module detects the fluorescence signal generated by the coaxial recording light on the information recording layer and sends it to the drive control module. If the focal 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 fluorescence signal until their focal centers are aligned. The fluorescence signal serves as a feedback signal, used to indicate whether there is a shift in the focal center position between the solid excitation light and the hollow suppression light.

11. The focusing servo method according to claim 10, characterized in that, 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, based on the received fluorescence signal. Specifically, aberration compensation for solid excitation light is achieved by moving the first compensation lens along the axial direction; aberration compensation for hollow suppression light is achieved by moving the second compensation lens along the axial direction.

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

13. The focusing servo method according to claim 12, characterized in that, The drive control module includes a controller and three, four, and five displacement actuators. After receiving a zoom layer jump request, the controller outputs a pre-set constant bias voltage to the three, four, and five displacement actuators respectively. The three displacement actuators drive the third compensation lens to move axially, and the fifth displacement actuator drives the recording objective and the servo objective 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 returns to the servo guiding layer.

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