Frequency splitting trimming method and system for gyroscopic resonant structure under femtosecond laser direct writing

Abstract

The application discloses a gyro resonant structure frequency splitting trimming method and system under femtosecond laser direct writing, and the trimming method comprises the following steps: determining the positions of high-frequency axes and low-frequency axes of the resonant structure; performing local stiffness reduction treatment and / or stiffness increase treatment on the resonant structure by using femtosecond laser until the frequency splitting of the resonant structure reaches or is smaller than a target value; the process of the stiffness reduction treatment is as follows: micro-nano softening structures are induced at positions corresponding to the high-frequency axes and / or positions adjacent to the high-frequency axes in the resonant structure to reduce the effective cross-sectional area or continuity, thereby reducing the stiffness of the local area on the resonant structure where the high-frequency axes are located; the process of the stiffness increase treatment is as follows: micro-nano strengthening structures are induced at positions corresponding to the low-frequency axes and / or positions adjacent to the low-frequency axes in the resonant structure to increase the stiffness of the local area on the resonant structure where the low-frequency axes are located. The application is applied to the field of gyroscopes, can effectively solve the existing problems of gyro resonant structure trimming, and further realizes low-damage, high-precision and high-efficiency mechanical trimming of micro gyroscopes.

Description

Technical Field

[0001] This invention relates to the field of gyroscope technology, specifically a method and system for frequency splitting and tuning of a gyroscope resonant structure using femtosecond laser direct writing. Background Technology

[0002] Inertial navigation calculates spatial attitude and position using the vehicle's acceleration and angle / angular velocity, and one of its core components is the gyroscope. The gyroscope is one of the most challenging devices to develop in an inertial navigation unit, and its performance directly determines the accuracy of the system's output. Fused silica micro-hemispherical resonator gyroscopes, with their high quality factor and good structural symmetry, have become one of the most promising high-performance gyroscopes. The micro-hemispherical resonator structure is the core sensing device of the gyroscope, and its symmetry directly determines the upper limit of the gyroscope's performance.

[0003] However, in actual processing, factors such as internal material inhomogeneity, dimensional errors in processing, and assembly errors can cause deviations in the stiffness of the resonant structure in various directions, resulting in two principal stiffness axes. The directions of these principal stiffness axes typically also deviate angularly from the electrode directions. Figure 1 As shown, frequency splitting is defined as the difference |f1-f2| between the natural frequencies of the resonant structure vibrating along the two principal stiffness axes. The direction with the highest frequency is defined as the high-frequency axis, and the direction with the lowest frequency is defined as the low-frequency axis. The two angles formed with the direction of the detection electrode are the two stiffness axis deflection angles θ1 and θ2. The existence of frequency splitting significantly affects the overall performance of the resonant gyroscope, and the initial frequency splitting is generally greater than 1Hz. This asymmetry will directly lead to the distortion of the standing wave precession trajectory, causing problems such as orthogonality error and decreased mechanical sensitivity. Studies have shown that excessive frequency splitting will reduce the zero-bias stability of the gyroscope, severely restricting its application in long-endurance and high-dynamic environments.

[0004] Currently, there are two methods for correcting frequency fragmentation: electrostatic correction and mechanical correction. Electrostatic correction applies a bias voltage to the high-frequency axis of the resonant structure, reducing the local stiffness of the resonant structure through the electrostatic negative stiffness effect, thereby reducing frequency fragmentation. Mechanical correction, on the other hand, involves etching a correction structure on the surface of the resonant structure, altering the local mass to control the modal frequency. After mechanical correction, the gyroscope's frequency difference remains stable, significantly improving its accuracy and stability. The mainstream mechanical correction process primarily utilizes femtosecond lasers and ion beams to etch microstructures along the low-frequency axis of the resonant structure, thereby reducing the local equivalent mass and achieving modal matching. Femtosecond laser correction places the gyroscope resonant structure to be corrected at the laser focusing position. Due to the extremely high peak power density of the femtosecond laser, electrons in the material absorb laser energy through nonlinear processes such as multiphoton absorption and tunneling ionization, leading to explosive disintegration of the material. The material is ejected as neutral atoms, ions, molecular clusters, and tiny particles, thus achieving the purpose of etching away mass. The ion beam etching process places the resonant structure in a high vacuum environment and uses the glow discharge principle to decompose argon gas into argon ions. The argon ions are accelerated by the anodic electric field and physically bombard the sample surface, which can achieve atomic-level material removal precision and achieve local etching effect on the resonant structure, thereby realizing frequency splitting and tuning.

[0005] Because the capacitor gap of a micro-hemispherical resonant gyroscope is greatly affected by temperature, when the gap changes, the change in local electrostatic negative stiffness caused by the applied voltage through electrostatic adjustment will change. Therefore, the electrostatic adjustment method has disadvantages such as poor stability and frequency fragmentation that changes with temperature and time. Furthermore, electrostatic adjustment adjusts the local stiffness by applying an external voltage, which cannot fundamentally suppress the frequency fragmentation of the resonant structure.

[0006] During femtosecond laser etching, processes such as condensation and redeposition of the removed material and plasma plume occur. Furthermore, when femtosecond lasers act on materials, the tensile stress concentration caused by the reflection of shock waves at free edges and the concentration of a small amount of thermal stress at geometric abrupt changes occur. Therefore, when using femtosecond lasers to directly remove mass from the toothed mass block of a micro-hemispherical resonant structure for adjustment, problems such as dust and significant structural damage may occur.

[0007] Ion beam etching has the disadvantage of low efficiency because it requires the resonant structure to be placed in a high vacuum environment. In addition, the equipment used in ion beam etching is complex, resulting in high cost and complicated adjustment processes. Furthermore, since sputtered products can be redeposited during ion beam etching, sputtered material atoms may be redeposited, inevitably causing contamination on or around the etched surface of the resonant structure. Summary of the Invention

[0008] To address the shortcomings of existing frequency splitting and tuning processes, such as severe contamination, reduced capacitance area, and significant surface damage, this invention provides a method and system for frequency splitting and tuning of gyroscope resonant structures using femtosecond laser direct writing. This method effectively solves the problems existing in gyroscope resonant structure tuning, thereby achieving low-damage, high-precision, and high-efficiency mechanical tuning of micro-gyroscopes.

[0009] To achieve the above objectives, the present invention provides a method for frequency splitting and tuning of a gyroscope resonant structure written directly by a femtosecond laser, comprising the following steps: The gyroscope is excited to cause the mode shape of its resonant structure to precess at a certain rate, and the modal parameters of the resonant structure, including frequency splitting and stiffness axis deflection, are measured during the precession of the mode shape of the resonant structure, thereby determining the positions of the high-frequency axis and low-frequency axis of the resonant structure. Femtosecond lasers are used to locally reduce the stiffness of the resonant structure and / or increase its stiffness until the frequency breakdown of the resonant structure reaches or falls below the target value. The process of reducing stiffness is as follows: a femtosecond laser is used to focus on the corresponding high-frequency axis and / or the adjacent position of the high-frequency axis inside the resonant structure to induce a micro-nano softening structure to reduce the effective cross-sectional area or continuity, thereby reducing the stiffness of the local area where the high-frequency axis is located on the resonant structure. The process of increasing stiffness is as follows: a femtosecond laser is used to focus on the corresponding low-frequency axis and / or adjacent positions inside the resonant structure to induce micro-nano reinforcement structures, thereby increasing the stiffness of the local area where the low-frequency axis is located on the resonant structure.

[0010] In one embodiment, the stiffness reduction process and the stiffness increase process can be performed iteratively until the frequency breakdown of the resonant structure reaches or falls below the target value.

[0011] In one embodiment, during the iterative process of the stiffness reduction treatment and the stiffness increase treatment: The first step is to induce a micro / nano softening structure at a position inside the resonant structure that coincides with the high-frequency axis; and / or induce a micro / nano strengthening structure at a position inside the resonant structure that coincides with the low-frequency axis. If the frequency split of the resonant structure does not reach or falls below the target value after completing the first step, then the second step is performed: Inside the resonant structure, at positions adjacent to the high-frequency axis on the left and right with a spacing of n1·d1, a micro / nano softening structure is induced in a direction parallel to the high-frequency axis; and / or inside the resonant structure, at positions adjacent to the low-frequency axis on the left and right with a spacing of n1·d1, a micro / nano strengthening structure is induced in a direction parallel to the low-frequency axis; where d1 is a preset vertical spacing base, n1 is a vertical spacing multiple, n1=1,2···,N1, and N1 is the maximum vertical multiple; If the frequency split of the resonant structure does not reach or falls below the target value after completing the second step, then the third step is performed: At the midpoint of the high-frequency axis inside the resonant structure, a micro / nano softening structure is induced in a direction perpendicular to the high-frequency axis, and the two ends of the induced micro / nano softening structure are connected to the outermost micro / nano softening structure in the second step; and / or at the midpoint of the low-frequency axis inside the resonant structure, a micro / nano strengthening structure is induced in a direction perpendicular to the low-frequency axis, and the two ends of the induced micro / nano strengthening structure are connected to the outermost micro / nano strengthening structure in the second step. If the frequency split of the resonant structure does not reach or falls below the target value after completing the third step, then the fourth step is performed: Inside the resonant structure, at positions adjacent to the micro / nano softening structure induced in the third step with a spacing of n2·d2, a micro / nano softening structure is induced in a direction perpendicular to the high-frequency axis, and the two ends of the induced micro / nano softening structure are connected to the outermost micro / nano softening structure in the second step; and / or inside the resonant structure, at positions adjacent to the micro / nano strengthening structure induced in the third step with a spacing of n2·d2, a micro / nano strengthening structure is induced in a direction perpendicular to the low-frequency axis, and the two ends of the induced micro / nano strengthening structure are connected to the outermost micro / nano strengthening structure in the second step; where d2 is the preset horizontal spacing base, n2 is the horizontal spacing multiple, n2=1,2···,N2, and N2 is the maximum horizontal multiple.

[0012] In one embodiment, the micro / nano reinforced structure includes a stress-strengthening structure, a densification structure, and an embedded nanoparticle structure.

[0013] In one embodiment, the micro / nano softening structure includes nanogratings, micropores, and microcracks.

[0014] To achieve the above objectives, the present invention also provides a femtosecond laser direct-write gyroscope resonator frequency splitting and tuning system, which uses the above-described method to perform gyroscope resonator frequency splitting and tuning.

[0015] In one embodiment, the gyroscope resonant structure frequency splitting and tuning system includes: The resonant structure frequency split test unit is used to control the gyroscope and simultaneously perform modal parameter testing using mode precession, and measure the frequency split and stiffness axis deflection of the resonant structure in real time. The frequency splitting tuning unit is used to induce micro / nano softening or micro / nano strengthening structures inside the resonant structure, thereby achieving frequency splitting tuning of the resonant structure.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention utilizes femtosecond lasers to induce micro / nano softening or micro / nano strengthening structures within the resonant structure to achieve frequency splitting and tuning. It reconstructs the mechanical properties of the material at the microscopic level, achieving precise bidirectional correction of the stiffness of the resonant structure. This not only fundamentally suppresses frequency splitting of the resonant structure but also avoids problems such as dust pollution, large structural damage, and low efficiency caused by direct mass removal. It can achieve a tuning effect with minimal damage and maximum efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the frequency splitting and stiffness axis deflection of the resonant structure in an embodiment of the present invention; Figure 2 This is a flowchart of the frequency splitting and tuning method for a gyroscope resonant structure written directly by a femtosecond laser in an embodiment of the present invention.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0022] Example 1 like Figure 2 The above describes a method for frequency splitting and tuning of a gyroscope resonant structure written directly using a femtosecond laser, as disclosed in this embodiment. The method mainly includes the following steps: The gyroscope is excited to cause the mode shape of its resonant structure to precess at a certain rate, and the modal parameters of the resonant structure, including frequency splitting and stiffness axis deflection, are measured during the precession of the mode shape of the resonant structure, thereby determining the positions of the high-frequency axis and the low-frequency axis of the resonant structure. Femtosecond lasers are used to locally reduce the stiffness of the resonant structure and / or increase its stiffness until the frequency breakdown of the resonant structure reaches or falls below the target value. The process of reducing stiffness is as follows: a femtosecond laser is used to focus on the corresponding high-frequency axis and / or the adjacent position of the high-frequency axis inside the resonant structure to induce a micro-nano softening structure to reduce the effective cross-sectional area or continuity, thereby reducing the stiffness of the local area where the high-frequency axis is located on the resonant structure. The process of increasing stiffness is as follows: a femtosecond laser is used to focus on the low-frequency axis and / or adjacent positions inside the resonant structure to induce micro-nano reinforcement structures, thereby increasing the stiffness of the local region where the low-frequency axis is located on the resonant structure.

[0023] This embodiment reduces stiffness along the high-frequency axis of the resonant structure through structural modification. Specifically, it uses a femtosecond laser to induce micro / nano softening structures (such as nanogratings, micropores, or microcracks) within the resonant structure to reduce the effective cross-sectional area or cross-sectional continuity, thereby lowering the stiffness of the resonant structure. Alternatively, it increases stiffness along the low-frequency axis by inducing micro / nano strengthening structures. Specifically, it increases the stiffness of the structure by generating stress-strengthening structures, densification structures, or nanoparticle-embedded structures within the structure using a femtosecond laser. By using a femtosecond laser to induce micro / nano softening or strengthening structures within the resonant structure to achieve frequency splitting and tuning, the mechanical properties of the material are reconstructed at the microscopic level, achieving precise bidirectional correction of the resonant structure's stiffness. This not only fundamentally suppresses frequency splitting of the resonant structure but also avoids problems such as dust pollution, significant structural damage, and low efficiency caused by direct mass removal, achieving a tuning effect with minimal damage and maximum efficiency.

[0024] During the process of radiating the interior of a resonant structure with a femtosecond laser, two different results can be achieved: inducing micro / nano-softening structures and inducing micro / nano-strengthening structures. This can be achieved by controlling parameters such as the single-pulse energy, scanning speed, repetition frequency, polarization state, and defocusing amount of the femtosecond laser. For example, when inducing micro / nano-softening structures such as micropores inside the resonant structure, a linearly polarized femtosecond laser can be focused into the structure with a single-pulse energy of 1.5 μJ, a repetition frequency of 100 kHz, and a scanning speed of 5 mm / s. When inducing micro / nano-strengthening structures such as compaction structures inside the resonant structure, a femtosecond laser can be focused into the structure with a single-pulse energy of 0.15 μJ, a repetition frequency of 500 kHz, and a scanning speed of 3 mm / s. In this embodiment, the stiffness reduction and stiffness increase processes can be performed iteratively until the frequency breakdown of the resonant structure reaches or falls below the target value. The specific implementation process is as follows: The first step is to induce a micro / nano softening structure at a position inside the resonant structure that coincides with the high-frequency axis; and / or induce a micro / nano strengthening structure at a position inside the resonant structure that coincides with the low-frequency axis. If the frequency split of the resonant structure does not reach or falls below the target value after completing the first step, then the second step is performed: Inside the resonant structure, at positions adjacent to the high-frequency axis on the left and right with a spacing of n1·d1, a micro / nano softening structure is induced in a direction parallel to the high-frequency axis; and / or inside the resonant structure, at positions adjacent to the low-frequency axis on the left and right with a spacing of n1·d1, a micro / nano strengthening structure is induced in a direction parallel to the low-frequency axis; where d1 is a preset vertical spacing base, n1 is a vertical spacing multiple, n1=1,2···,N1, and N1 is the maximum vertical multiple; If the frequency split of the resonant structure does not reach or falls below the target value after completing the second step, then the third step is performed: At the midpoint of the high-frequency axis inside the resonant structure, a micro / nano softening structure is induced in a direction perpendicular to the high-frequency axis, and the two ends of the induced micro / nano softening structure are connected to the outermost micro / nano softening structure in the second step; and / or at the midpoint of the low-frequency axis inside the resonant structure, a micro / nano strengthening structure is induced in a direction perpendicular to the low-frequency axis, and the two ends of the induced micro / nano strengthening structure are connected to the outermost micro / nano strengthening structure in the second step. If the frequency split of the resonant structure does not reach or falls below the target value after completing the third step, then the fourth step is performed: Inside the resonant structure, at positions adjacent to the micro / nano softening structure induced in the third step with a spacing of n2·d2, a micro / nano softening structure is induced in a direction perpendicular to the high-frequency axis, and the two ends of the induced micro / nano softening structure are connected to the outermost micro / nano softening structure in the second step; and / or inside the resonant structure, at positions adjacent to the micro / nano strengthening structure induced in the third step with a spacing of n2·d2, a micro / nano strengthening structure is induced in a direction perpendicular to the low-frequency axis, and the two ends of the induced micro / nano strengthening structure are connected to the outermost micro / nano strengthening structure in the second step; where d2 is the preset horizontal spacing base, n2 is the horizontal spacing multiple, n2=1,2···,N2, and N2 is the maximum horizontal multiple.

[0025] In a preferred embodiment, during the second step, the induced micro / nano softening structure treatment on the high-frequency axis and the induced micro / nano strengthening structure treatment on the low-frequency axis are performed alternately, with the value of n1 gradually increasing from 1. For example, after setting n1=1, a micro / nano softening structure is first induced at the position adjacent to the left of the high-frequency axis with a spacing of n1·d1. If further adjustment is needed, a micro / nano softening structure is induced at the position adjacent to the right of the high-frequency axis with a spacing of n1·d1. If further adjustment is needed, a micro / nano strengthening structure is induced at the position adjacent to the left of the low-frequency axis with a spacing of n1·d1. If further adjustment is still needed, a micro / nano strengthening structure is induced at the position adjacent to the right of the low-frequency axis with a spacing of n1·d1. Subsequent adjustments are made by sequentially setting n1=2...N1 and repeating the above adjustment operation until the second step is completed.

[0026] Preferably, during the fourth step, the induced micro / nano softening structure treatment for the high-frequency axis and the induced micro / nano strengthening structure treatment for the low-frequency axis are performed alternately, with the value of n2 gradually increasing from 1. For example, after setting n2=1, a micro / nano softening structure is first induced at the position adjacent to the micro / nano softening structure induced in the third step, with a spacing of n2·d2. If further adjustment is needed, a micro / nano softening structure is induced at the position adjacent to the micro / nano softening structure induced in the third step, with a spacing of n2·d2. If further adjustment is needed, a micro / nano strengthening structure is induced at the position adjacent to the micro / nano strengthening structure induced in the third step, with a spacing of n2·d2. If further adjustment is still needed, a micro / nano strengthening structure is induced at the position adjacent to the micro / nano strengthening structure induced in the third step, with a spacing of n1·d1. Subsequent adjustments are made by setting n2=2...N2 and repeating the above adjustment operation until the fourth step is completed. If the frequency splitting after the fourth step does not reach or is less than the target value, the value of N2 is increased accordingly.

[0027] It is worth noting that, although this embodiment Figure 2 The steps are shown sequentially as indicated by the arrows, but they are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order in which these steps are performed; they can be executed in other orders, such as... Figure 2 The stiffness reduction and stiffness increase treatments can be performed simultaneously or selectively. Furthermore, Figure 2 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0028] Example 2 Based on the femtosecond laser direct-write gyroscope resonant structure frequency splitting and tuning method in Example 1, this example discloses a femtosecond laser direct-write gyroscope resonant structure frequency splitting and tuning system. This gyroscope resonant structure frequency splitting and tuning system includes a resonant structure frequency splitting test unit and a frequency splitting and tuning unit, specifically: The resonant structure frequency split test unit is used to control the gyroscope and simultaneously use mode precession to test modal parameters, and measure the frequency split and stiffness axis deflection of the resonant structure in real time. The frequency splitting and tuning unit consists of a femtosecond laser, a six-axis motion platform, a laser processing optical path, a femtosecond laser control unit, and an optical element control unit. It is used to induce micro / nano softening or micro / nano strengthening structures inside the resonant structure, thereby achieving frequency splitting and tuning of the resonant structure.

[0029] In this embodiment, the specific working process and working principle of the resonant structure frequency splitting test unit and the frequency splitting tuning unit are the same as those in Embodiment 1, so they will not be described again in this embodiment. Each unit module can be implemented entirely or partially through software, hardware, or a combination thereof. Each unit module can be embedded in the processor of the computer device in hardware form or independent of it, or it can be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to each of the above unit modules.

[0030] The above description is only a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A method for frequency splitting and tuning of a gyroscope resonant structure written directly by a femtosecond laser, characterized in that, Includes the following steps: The gyroscope is excited to cause the mode shape of its resonant structure to precess at a certain rate, and the modal parameters of the resonant structure, including frequency splitting and stiffness axis deflection, are measured during the precession of the mode shape of the resonant structure, thereby determining the positions of the high-frequency axis and the low-frequency axis of the resonant structure. Femtosecond lasers are used to locally reduce the stiffness of the resonant structure and / or increase its stiffness until the frequency breakdown of the resonant structure reaches or falls below the target value. The process of reducing stiffness is as follows: a femtosecond laser is used to focus on the corresponding high-frequency axis and / or the adjacent position of the high-frequency axis inside the resonant structure to induce a micro-nano softening structure to reduce the effective cross-sectional area or continuity, thereby reducing the stiffness of the local area where the high-frequency axis is located on the resonant structure. The process of increasing stiffness is as follows: a femtosecond laser is used to focus on the corresponding low-frequency axis and / or adjacent positions of the low-frequency axis inside the resonant structure to induce a micro-nano strengthening structure, thereby increasing the stiffness of the local area where the low-frequency axis is located on the resonant structure. The stiffness reduction process and the stiffness increase process are performed iteratively until the frequency breakdown of the resonant structure reaches or falls below the target value. During the iterative process of stiffness reduction and stiffness increase: The first step is to induce a micro / nano softening structure at a position inside the resonant structure that coincides with the high-frequency axis; and / or induce a micro / nano strengthening structure at a position inside the resonant structure that coincides with the low-frequency axis. If the frequency split of the resonant structure does not reach or falls below the target value after completing the first step, then the second step is performed: Inside the resonant structure, at positions adjacent to the high-frequency axis on the left and right with a spacing of n1·d1, a micro / nano softening structure is induced in a direction parallel to the high-frequency axis; and / or inside the resonant structure, at positions adjacent to the low-frequency axis on the left and right with a spacing of n1·d1, a micro / nano strengthening structure is induced in a direction parallel to the low-frequency axis; where d1 is a preset vertical spacing base, n1 is a vertical spacing multiple, n1=1,2···,N1, and N1 is the maximum vertical multiple; If the frequency split of the resonant structure does not reach or falls below the target value after completing the second step, then the third step is performed: At the midpoint of the high-frequency axis inside the resonant structure, a micro / nano softening structure is induced in a direction perpendicular to the high-frequency axis, and the two ends of the induced micro / nano softening structure are connected to the outermost micro / nano softening structure in the second step; and / or at the midpoint of the low-frequency axis inside the resonant structure, a micro / nano strengthening structure is induced in a direction perpendicular to the low-frequency axis, and the two ends of the induced micro / nano strengthening structure are connected to the outermost micro / nano strengthening structure in the second step. If the frequency split of the resonant structure does not reach or falls below the target value after completing the third step, then the fourth step is performed: Inside the resonant structure, at positions adjacent to the micro / nano softening structure induced in the third step with a spacing of n2·d2, a micro / nano softening structure is induced in a direction perpendicular to the high-frequency axis, and the two ends of the induced micro / nano softening structure are connected to the outermost micro / nano softening structure in the second step; and / or inside the resonant structure, at positions adjacent to the micro / nano strengthening structure induced in the third step with a spacing of n2·d2, a micro / nano strengthening structure is induced in a direction perpendicular to the low-frequency axis, and the two ends of the induced micro / nano strengthening structure are connected to the outermost micro / nano strengthening structure in the second step; where d2 is the preset horizontal spacing base, n2 is the horizontal spacing multiple, n2=1,2···,N2, and N2 is the maximum horizontal multiple.

2. The method for frequency splitting and tuning of a gyroscope resonant structure written directly by femtosecond laser according to claim 1, characterized in that, The micro / nano reinforced structure includes stress-strengthening structures, densification structures, and embedded nanoparticle structures.

3. The method for frequency splitting and tuning of a gyroscope resonant structure written directly by femtosecond laser according to claim 1, characterized in that, The micro / nano softening structure includes nanogratings, micropores, and microcracks.

4. A frequency splitting and tuning system for a gyroscope resonant structure written directly by a femtosecond laser, characterized in that, The frequency splitting and tuning of the gyroscope resonant structure is performed using the method described in any one of claims 1 to 3.

5. The femtosecond laser direct-write gyroscope resonant structure frequency splitting and tuning system according to claim 4, characterized in that, The frequency splitting and tuning system of the gyroscope resonant structure includes: The resonant structure frequency split test unit is used to control the gyroscope and simultaneously perform modal parameter testing using mode precession, and measure the frequency split and stiffness axis deflection of the resonant structure in real time. The frequency splitting tuning unit is used to induce micro / nano softening or micro / nano strengthening structures inside the resonant structure, thereby achieving frequency splitting tuning of the resonant structure.

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