A laser ablation and parameter optimization system and method for hemispherical resonator

Abstract

The application discloses a kind of laser ablation and parameter optimization system and method of hemispherical resonator, the system includes laser, control system, frequency difference test module, vacuum cavity, and electric rotating base, work platform, vibration measuring fixture, electric control excitation small hammer and vibration damper are set in vacuum cavity;The work platform is installed on electric rotating base;The vibration damper, vibration measuring fixture, electric control excitation small hammer are all installed on work platform.Parameter optimization method is invented using the ablation system, according to the experimental sample of real-time increase, judge fitting matching degree, dynamically update fitting function.Laser tuning parameters are determined according to fitting function, to ensure the accuracy of ablation amount, improve tuning efficiency and convergence.The application is widely applicable to the size of resonator, and provides technical support for high-precision hemispherical resonator engineering development.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hemispherical resonator gyroscopes, in particular, to a laser ablation and parameter optimization system and method for a hemispherical resonator. BACKGROUND

[0002] As a new type of solid-state inertial sensor for measuring angular rate or attitude angle, the hemispherical resonator gyroscope (HRG) has a wide application prospect in the fields of navigation, aviation, spaceflight, deep space exploration, satellite attitude measurement, and ship navigation, etc. due to its simple structure, high precision, small mass, long service life, and high reliability. The performance of the hemispherical resonator, the core component of the gyroscope, directly determines the overall performance of the gyroscope. High-performance resonators are usually made of fused quartz glass, which has the advantages of low thermal expansion rate, isotropy, and high quality factor. However, the key to ensuring high performance of the gyroscope lies in the fact that the resonator must have a very small frequency split value. Batch production and processing techniques inevitably introduce defects, including axisymmetric imperfections, uneven ring mass distribution, stiffness defects, and anisotropic damping. These defects can cause significant frequency splitting, which can seriously affect the working precision and service life of the gyroscope. Therefore, it is necessary to make the resonator ring mass distribution uniform through leveling processes to effectively suppress frequency splitting and ultimately ensure high precision and long service life of the gyroscope.

[0003] Laser spot ablation can achieve precise removal from nanometer to micrometer scale, and is a very effective, low-cost and fine non-contact processing technology. Although the laser tuning process can locally remove mass, the process is tedious and relies on the operator's practical experience to adjust the laser spot position and ablation parameters. The processing time and frequency difference results are greatly affected by human judgment, resulting in poor process repeatability and unstable tuning effect. Especially when the frequency difference is less than 0.01 Hz, the unstable laser tuning effect can greatly affect the leveling time and even exacerbate the unevenness of the resonator ring mass distribution (excessive mass removal). Therefore, although laser tuning has advantages in principle, the unstable ablation energy and poor repeatability of its core seriously restrict the tuning accuracy, making it difficult to reliably balance the resonator surface mass.

[0004] For example, the invention patents with announcement numbers CN117606510A and CN119984217A both disclose certain hemispherical resonator tuning technology, but the above two patents still cannot solve the above problems.

[0005] Therefore, it is urgent to develop an innovative laser ablation and parameter optimization method for a hemispherical resonator. This method can collect a large amount of real data for weight removal and tuning, use the laser ablation parameters of the actual device as a basis, and fit the relationship between the laser parameters and the frequency difference tuning value, providing a solid data foundation for the closed-loop optimization of subsequent frequency difference tuning process parameters SUMMARY

[0006] Therefore, the first object of the present application is to provide a laser ablation and parameter optimization system for hemispherical resonators, which has the characteristics of reasonable design and high practicability.

[0007] To solve the above technical problems, the technical solution of the present application is:

[0008] A laser ablation and parameter optimization system for hemispherical resonators, comprising a laser, a control system, a frequency difference testing module, a vacuum chamber, and an electric rotating base, a workbench, a vibration testing clamp, an electric control excitation small hammer and a vibration damping device arranged in the vacuum chamber; the workbench is installed on the electric rotating base; the vibration damping device, the vibration testing clamp and the electric control excitation small hammer are all installed on the workbench.

[0009] The vacuum chamber is provided with a testing window and a visual window.

[0010] The laser is used to emit laser from the visual window to the tuning position of the hemispherical resonator for ablation.

[0011] The electric control excitation small hammer is used to excite the hemispherical resonator to make it enter the second-order vibration mode.

[0012] The vibration damping device is used to increase the vibration damping of the hemispherical resonator to force it to restore to a static state.

[0013] The vibration testing clamp is used to clamp the hemispherical resonator to be tested.

[0014] The frequency difference testing module is provided with a laser vibration tester, which is used to test the frequency difference of the vibrating hemispherical resonator in the vacuum chamber through the testing window to collect the tuning frequency difference value of the actual ablation.

[0015] The control system is electrically connected with the frequency difference testing module and the laser, and is used to set the power, frequency and speed of the laser according to the tuning frequency difference value.

[0016] Therefore, the second object of the present application is to provide a laser ablation method for hemispherical resonators, which has the characteristics of reasonable design and high practicability.

[0017] To solve the above technical problems, the technical solution of the present application is:

[0018] A laser ablation and parameter optimization method for hemispherical resonators, which is implemented based on the above-mentioned laser ablation and parameter optimization system, comprising:

[0019] S1, before the vacuum chamber is closed, the laser, the vibration damping device and the electric control excitation small hammer are adjusted to the expected preparation state.

[0020] S2, excite the to-be-tested hemispherical resonator by the electrically controlled excitation hammer to make it enter a second-order vibration mode, and test and ablate the hemispherical resonator in the state; after completion, quickly damp the hemispherical resonator by the damping damper to restore the hemispherical resonator to a static state; wherein the testing and ablation of the hemispherical resonator in the state comprises:

[0021] S21, find a low-frequency axis position of the hemispherical resonator by rotating the base, then rotate an angle K and perform a frequency difference test to obtain a frequency difference;

[0022] S22, before laser ablation, set parameters of the laser by the control system;

[0023] S23, rotate an angle -K to return to the original low-frequency axis position, and ablate related directions of the hemispherical resonator respectively based on the low-frequency axis position measured this time;

[0024] S24, after ablation, test the frequency difference of the hemispherical resonator again, and subtract the frequency differences measured after adjacent ablation, that is, the frequency difference adjustment amount under this time laser parameters;

[0025] S3, collect data of this time laser parameters and the frequency difference adjustment amount, and analyze and fit the data together with previously measured data to obtain a real-time updated fitting curve as a basis for setting laser ablation parameters next time.

[0026] S4, repeat steps S2-S3 N times until the frequency difference meets the requirements.

[0027] Preferably, the S1 specifically comprises:

[0028] Before the vacuum cavity is closed, adjust the height of the laser, the damping damper and the electrically controlled excitation hammer, so that the laser ablation position, the damping and the horizontal position of the knocking are the same each time of testing and ablation;

[0029] Select a suitable driving voltage of the electrically controlled excitation hammer to make the electrically controlled excitation hammer reset immediately after knocking the hemispherical resonator;

[0030] Adjust the laser light source to be vertically incident to the visual window to focus the laser spot to the hemispherical resonator adjustment position.

[0031] Preferably, in step S2, if the measured initial intrinsic axis is a high-frequency axis position, rotate 45° again to obtain an initial low-frequency axis position.

[0032] Preferably, 0 degrees < K < 22.5 degrees.

[0033] Preferably, for hemispherical resonators of the same size, the laser parameters can be set directly using the fitted data curves; for hemispherical resonators of different sizes, the first laser ablation is used to determine the parameters, and the limitation is that the change after laser ablation must be greater than the minimum resolution of the frequency difference test module.

[0034] Preferably, the analysis of the correspondence between N-1 frequency difference adjustment values ​​and laser parameters, and the analysis and fitting of all data, specifically includes:

[0035] By performing nonlinear fitting with a certain parameter of the laser as a variable, the fitting curve of that parameter and the frequency difference adjustment amount of laser ablation is obtained;

[0036] The nonlinear fitting formula is as follows:

[0037] Δf n -Δf n-1 =a·(x(p n-1 )) b ;

[0038] Where, Δf n Let Δf be the frequency difference of the Nth time. n-1 p is the frequency difference of the (N-1)th time. n-1 Let be a parameter of the laser in the (N-1)th laser iteration, and a and b be the fitted variation values.

[0039] The collected data is fed into the fitted curve in real time for updating and iteration to obtain a new fitted curve;

[0040] When setting the laser parameters for the N+1th ablation, the optimized laser parameters are obtained by analyzing the curve fitted by the frequency difference adjustment amount of the previous N-1 ablation.

[0041] The main technical effects of this invention are reflected in the following aspects:

[0042] 1. Improve accuracy. Based on the real-time increase of experimental samples, the original fitting curve is updated in real time, and a new fitting curve of laser parameters and frequency difference adjustment is generated iteratively. The fitting effect is dynamically updated, the fitting degree is judged, and the next laser parameter setting value can be effectively determined, ensuring the accuracy of the frequency difference adjustment. When the sample size reaches a certain level, the obtained fitting curve can get as close as possible to the true value.

[0043] 2. Improved Efficiency. After establishing a parameter library, laser parameters can be quickly determined for situations where the spatial adjustment position remains unchanged, improving the adjustment efficiency of hemispherical resonators. With a comprehensive hemispherical resonator parameter library, the theoretically shortest time can be achieved for laser ablation of all hemispherical resonators for deduplication and leveling. The fitted curves obtained using the above method can be supplemented with other parameters, such as chamber temperature, laser spot shape, and laser ablation path, to meet the requirements for efficient deduplication and leveling of different types of hemispherical resonators. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the laser ablation and parameter optimization system in the embodiment;

[0045] Figure 2 This is a schematic diagram of the operation process of the laser ablation and parameter optimization system in the embodiment;

[0046] Figures 3-4 In this embodiment, the fitted curves of laser parameters and frequency difference adjustment are obtained by collecting actual ablation parameters, with laser power as the variable and laser speed and frequency as the quantitative parameters.

[0047] Reference numerals: 1. Laser; 2. Control system; 3. Frequency difference test module; 31. Vibration meter; 4. Vacuum chamber; 5. Electric rotating base; 6. Working platform; 7. Vibration measuring fixture; 8. Vibration damper; 9. Electrically controlled excitation hammer. Detailed Implementation

[0048] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so that the technical solution of the present invention can be more easily understood and mastered.

[0049] like Figure 1 The system shown is a laser ablation and parameter optimization system for a hemispherical harmonic oscillator, which includes a laser 1, a control system 2, a frequency difference testing module 3, a vacuum cavity 4, and an electric rotating base 5, a working platform 6, a vibration measuring fixture 7, an electrically controlled excitation hammer 9, and a vibration damper 8 disposed in the vacuum cavity 4.

[0050] Laser 1 is a CO2 laser.

[0051] Vacuum chamber 4 is equipped with a test window and a viewing window.

[0052] The working platform 6 is mounted on the electric rotating base 5; the vibration damper 8, the vibration measuring clamp 7, and the electrically controlled excitation hammer 9 are all mounted on the working platform 6.

[0053] The vibration measuring fixture 7 is used to hold the hemispherical resonator under test. Since the vibration measuring fixture 7 is existing technology, it will not be described in detail in this embodiment. It is worth noting that during installation, the vibration measuring fixture 7 needs to be adjusted to ensure that the center of the hemispherical resonator coincides with the rotation axis of the electric rotating base 5.

[0054] The laser 1 is used to emit laser from the visual window to the tuning position of the hemispherical resonator.

[0055] The electrically controlled excitation hammer 9 is used to excite the hemispherical resonator to make it enter the second order vibration mode.

[0056] The vibration damping device 8 is used to damp the hemispherical resonator, which mainly comprises a support, a driving motor, a damping rod and a sponge; the driving motor is installed on the support, the damping rod is installed on the output end of the driving motor, and the sponge is installed on the end of the damping rod. By controlling the driving motor to rotate by a certain angle, the damping rod is driven to rotate, thereby driving the sponge to contact the hemispherical resonator, so as to realize damping. The structure principle of the vibration damping device 8 is the prior art, and will not be described here in detail.

[0057] The frequency difference test module 3 is configured with a laser vibration tester 31, which is used to test the frequency difference of the hemispherical resonator in the vacuum chamber 4 through the test window, so as to obtain the actual ablation tuning frequency difference.

[0058] The control system 2 is electrically connected with the laser 1, and after the parameters of the power, frequency and speed of the laser are determined according to the curve of the fitting frequency difference tuning amount, the parameters are input into the control system 2 for the following laser ablation.

[0059] Based on the above system, the embodiment mainly introduces a laser ablation and parameter optimization method of a hemispherical resonator, which comprises:

[0060] S1, before the vacuum chamber 4 is closed, the vibration tester 31, the laser 1, the vibration damping device 8 and the electrically controlled excitation hammer 9 are adjusted to the expected preparation state, and the laser spot is focused on the tuning position of the hemispherical resonator.

[0061] S11, specifically comprising: before the vacuum chamber 4 is closed, the height of the vibration damping device 8 and the electrically controlled excitation hammer 9 is adjusted, so that the relative height of the vibration damping device 8 and the electrically controlled excitation hammer 9 to the working platform 6 is consistent each time;

[0062] S12, selecting a suitable driving voltage of the electrically controlled excitation hammer 9, so that the electrically controlled excitation hammer 9 resets immediately after knocking the hemispherical resonator shell;

[0063] S13, adjusting the laser 1 light source to be vertically incident to the tuning position of the hemispherical resonator.

[0064] S2, exciting the hemispherical resonator to be tested by the electrically controlled excitation hammer 9 to make it enter the second order vibration mode, and testing and ablating the hemispherical resonator in this state; after completion, the hemispherical resonator is quickly damped by the vibration damping device 8 to restore the hemispherical resonator to a static state; wherein the testing and ablation of the hemispherical resonator in this state comprises:

[0065] S21, find the low frequency axis position of the hemispherical resonator, then rotate angle K and conduct frequency difference test to obtain the frequency difference.

[0066] S22, before laser ablation, set the power, speed and frequency of the laser 1 through the control system 2;

[0067] S23, rotate angle -K and return to the original low frequency axis position, and then ablate the hemispherical resonator at 0°, 90°, 180° and 270° respectively based on the low frequency axis position obtained in this test.

[0068] In the above steps, 0° < K < 22.5°, and preferably K = 5°.

[0069] It is worth noting that: if the same size hemispherical resonator is to be leveled, the data curve fitted can be directly used for laser parameter setting; if different size hemispherical resonators are to be leveled, the first laser ablation is a parameter exploration, and the setting limit is that the change after laser ablation should be greater than the minimum resolution of the frequency difference test module 3, and the change is the change of the frequency difference between adjacent two ablations, for example, the minimum resolution of the system is 2mHz, the last time is 52mHz, and the change is 1mHz, which is less than the resolution, and the next time the measured value may still be 52mHz.

[0070] In the above steps, if the measured initial natural axis is a high frequency axis position, rotate 45° to obtain the initial low frequency axis position. Because in the second order vibration mode, the hemispherical resonator has 8 natural axes spaced 45° apart, the natural axes are arranged in a fixed interval of 45°, and the frequency difference test module 3 can determine whether the natural axis is a low frequency axis or a high frequency axis, if it is a high frequency axis, rotate 45° to reach the low frequency axis position.

[0071] S24, after ablation, test the frequency difference of the hemispherical resonator again, and subtract the frequency differences measured after adjacent two ablations, that is, the frequency difference adjustment amount under the current laser parameters;

[0072] S3, collect and analyze the corresponding relationship data of N-1 frequency difference adjustment amounts and the power, speed and frequency of the laser 1, obtain a real-time updated fitting curve, and use it as the basis for setting the laser power, speed and frequency of the laser 1 for the next ablation.

[0073] S4, repeat steps S2-S3 N times until the frequency difference meets the requirements.

[0074] The above steps specifically include:

[0075] Take one of the power, speed and frequency of the laser 1 as a variable, and set the others as constants to fit respectively, and obtain the fitting curve of the parameter and the frequency difference adjustment amount of the laser ablation;

[0076] The collected data is put into the fitting curve for real-time updating iteration to obtain a new fitting curve;

[0077] The nonlinear fitting formula is:

[0078] Δf n -Δf n-1 =a·(x(p n-1 )) b ;

[0079] Δf n is the frequency difference of the Nth time, Δf n-1 is the frequency difference of the N-1th time, p n-1 is the laser parameter of the N-1th time, and a and b are the fitting variation amounts.

[0080] When the laser parameters of the N+1th ablation are set, the optimized laser power, speed and frequency are obtained by analyzing the curve fitted according to the frequency difference adjustment amounts of the previous N-1 times.

[0081] In the above steps, the nonlinear curve fitting is performed on the data of the previous N-1 times, the Levenberg-Marquardt optimization algorithm is used for the nonlinear fitting formula, iterative convergence is obtained, and the fitting curve and the corresponding R 2 are obtained. 2 Based on the absolute value of R 2 , the fitting curve with the maximum R 2 is used to determine the setting of the laser ablation parameters of the Nth time; the corresponding relationship data of the frequency difference adjustment amount and the laser power, speed and frequency are substituted into the fitting curve, the new fitting curve and R 2 are obtained by re-fitting analysis.

[0082] Based on the above method, a specific implementation process is given in this embodiment:

[0083] The original size of the polished and pickled hemispherical resonator is removed and adjusted to a flat surface, the initial Q value is 9.6 million, and the initial frequency difference is 238 mHz. The hemispherical resonator is fixed on the electric rotating base 5, the distance between the hemispherical resonator shell and the working platform 6 is adjusted to 3.5 cm; the driving voltage of the electric control excitation small hammer 9 and the damper is set to 8.5 V, the focusing position of the laser spot is checked before the vacuum chamber 4 is closed, the knocking position of the electric control excitation small hammer 9 and the acting position of the damper are checked; the laser ablation and the frequency difference test are performed in the range of less than 10 -3 pa, and the temperature condition is room temperature.

[0084] According to Figure 3The laser power is the variable, the laser speed is 500mm / s and the laser frequency is 200kHz, the initial frequency difference is between the frequency difference adjustment amount of the power 28% and the power 29%, so the power setting of the first ablation is 28%, and other parameters remain unchanged.

[0085] Subsequently, the second frequency difference and the second low frequency position are measured, the corresponding relationship data of the frequency difference adjustment amount of the first ablation and the power, speed and frequency of the laser 1 are brought into the fitting curve again to update iteration, a new fitting curve is obtained, and the R 2 The maximum fitting curve is used as the basis to optimize the parameters of the next laser ablation. Using this method, the frequency difference of the resonator can be reduced to below 10mHz in four or five laser ablations, the total time cost is less than 4 hours, and there is almost no decay effect on the Q value.

[0086] Of course, the above is only a typical example of the present application, in addition to this, the present application can have other various specific embodiments, any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of the present application.

Claims

1. A method of laser ablation and parameter optimization of a hemispherical resonator, characterized in that, The system is based on a laser ablation and parameter optimization system, which includes a laser (1), a control system (2), a frequency difference testing module (3), a vacuum chamber (4), and an electric rotating base (5), a working platform (6), a vibration measuring fixture (7), an electrically controlled excitation hammer (9), and a vibration damper (8) installed in the vacuum chamber (4). The working platform (6) is mounted on the electric rotating base (5). The vibration damper (8), the vibration measuring fixture (7), and the electrically controlled excitation hammer (9) are all mounted on the working platform (6). The laser ablation and parameter optimization method includes: S1. Before the vacuum chamber (4) is closed, adjust the laser (1), the vibration damper (8) and the electrically controlled excitation hammer (9) to the expected ready state. S2. The hemispherical harmonic oscillator under test is excited by an electrically controlled excitation hammer (9) to enter the second-order vibration mode, and the hemispherical harmonic oscillator is tested and ablated in this state; after completion, the hemispherical harmonic oscillator is quickly stopped by a vibration damper (8) to restore the hemispherical harmonic oscillator to a static state; wherein, the testing and ablation of the hemispherical harmonic oscillator in this state includes: S21. Locate the low-frequency axis position of the hemispherical harmonic oscillator, then rotate it by an angle K and perform a frequency difference test to obtain the frequency difference; S22. Before laser ablation, the parameters of the laser (1) are set by the control system (2); S23. After rotating by an angle of -K, return to the original low-frequency axis position. Using the low-frequency axis position measured this time as a reference, ablate the relevant orientations of the hemispherical harmonic oscillator respectively. S24. After the ablation is completed, the frequency difference of the hemispherical harmonic oscillator is tested again. The frequency difference measured after two adjacent ablations is subtracted, which is the frequency difference adjustment amount under the laser parameters. S3. Collect the data of laser parameters and frequency difference adjustment amount, and analyze and fit them together with the previously measured data to obtain the real-time updated fitting curve, which will serve as the basis for setting the laser (1) ablation parameters next time. S4. Repeat steps S2-S3 N times until the frequency difference meets the requirements.

2. A method of laser ablation and parameter optimization of a hemispherical resonator as claimed in claim 1, characterized in that, S1 specifically includes: Before the vacuum chamber (4) is closed, adjust the height of the laser (1), the vibration damper (8) and the electrically controlled excitation hammer (9) so that the laser ablation position, vibration damping and the horizontal position of the hammer are the same for each test and ablation. Select a suitable driving voltage for the electrically controlled excitation hammer (9) so that the electrically controlled excitation hammer (9) immediately resets after hitting the hemispherical resonator; Adjust the laser (1) light source to be incident vertically onto the viewing window so that the laser spot is focused onto the adjustment position of the hemispherical harmonic oscillator.

3. A method of laser ablation and parameter optimization of a hemispherical resonator as claimed in claim 1, characterized in that, In step S2, if the measured initial natural axis is the high-frequency axis position, then rotate it by 45° to obtain the initial low-frequency axis position.

4. A method of laser ablation and parameter optimization of a hemispherical resonator as claimed in claim 1, characterized in that, 0 < K < 22.5 degrees.

5. A method of laser ablation and parameter optimization of a hemispherical resonator as claimed in claim 1, characterized in that, If hemispherical harmonic oscillators of the same size are leveled, the laser parameters can be set directly using the fitted data curves; if hemispherical harmonic oscillators of different sizes are leveled, the first laser ablation is used as a parameter baseline, and the setting limit is: the change after laser ablation must be greater than the minimum resolution of the frequency difference test module (3).

6. A method of laser ablation and parameter optimization of a hemispherical resonator as claimed in claim 1, characterized in that, In step S3, the fitting curve is analyzed and updated in real time, specifically including: The laser power of the laser (1) is taken as a variable to perform nonlinear fitting to obtain a fitting curve of the laser power and the frequency difference adjustment amount of the laser ablation, wherein the nonlinear fitting formula is: ； wherein, is the frequency difference for the Nth time, is the frequency difference for the N-1th time, is the laser power for the N-1th time, and a, b are the fitting variation. The collected data is immediately put into the fitting curve to update and iterate to obtain a new fitting curve; When the laser parameters of the N+1th ablation are set, the optimized laser parameters are analyzed according to the curve fitted by the frequency difference adjustment amounts of the previous N-1 times.

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