Special adjusting frame for film coating stress detection of hemispherical harmonic oscillator and detection method of special adjusting frame

Abstract

The invention relates to a special adjusting frame for film coating stress detection of a hemispherical harmonic oscillator and a detection method thereof, the adjusting frame comprises a three-jaw chuck, an axial and transverse rotating table, a two-dimensional and three-dimensional displacement table and a spectrum confocal probe, the harmonic oscillator can be firmly clamped, the accurate adjustment and rotation of the harmonic oscillator in multiple dimensions can be realized, and the concentricity of the harmonic oscillator and a rotating shaft can be ensured; the detection method comprises the following steps: detecting the surface types of uncoated and coated harmonic oscillators by using a spherical interferometer, adjusting the positions of the harmonic oscillators through a seven-dimensional adjusting frame, reconstructing a complete surface type by using a splicing algorithm, comparing surface type data before and after coating, and calculating the stress of the harmonic oscillators through a deduced stress-strain formula. According to the invention, the thermal stress of the coating film of the harmonic oscillator can be directly detected, the harmonic oscillator and the film are not damaged, the detection efficiency is relatively high, and the detection precision is ensured at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of optical detection, and in particular is a special adjustment frame for detecting stress of a hemispherical resonator coating and a method for detecting stress of a hemispherical resonator coating. Background Art

[0002] The components of the hemispherical resonator gyroscope are all made of high-precision fused quartz glass to ensure low zero-bias stability during operation. However, if the hemispherical resonator gyroscope sealed in a vacuum container wants to generate micro-vibrations through electrostatic excitation, it is necessary to metallize the surface to make it have good conductivity.

[0003] The quality factor of quartz glass material is expressed by Q value, which is an important performance index of oscillator acoustics, and its value is closely related to the attenuation of energy. The fundamental reason affecting the Q value of the hemispherical resonator is internal friction, that is, the energy loss phenomenon caused by various defects in the vibration process: internal friction caused by asymmetric distortion of the face-centered cubic lattice structure, ordered internal friction induced by substitutional atomic stress, grain boundary internal friction and dislocation internal friction. The uniformity of the metal film and the residual stress generated after coating will cause internal friction. In this process, the residual stress caused by the preparation process of the metal film will reduce the quality factor Q value of the resonator to 20% to 30% of the Q value before coating. On the hemispherical resonator after coating, if the residual stress of the film is manifested as a large tensile stress, the film layer is prone to cracking; on the contrary, if it is manifested as a large compressive stress, the film layer is prone to blistering, which leads to film failure. Therefore, the accurate measurement of the residual stress of the film is an urgent problem to be solved.

[0004] Existing stress measurement methods have obvious shortcomings. Traditional mechanical methods, such as the gluing method and the scratch method, measure stress values ​​by completely releasing residual stress, which will cause certain damage to the workpiece and are not suitable for high-precision hemispherical resonant gyroscopes. The main feature of physical measurement methods is that they do not cause damage to the sample to be measured, mainly including the Stoney formula method, the X-ray diffraction method, and the ultrasonic method. The Stoney formula method cleverly uses the substrate curvature to measure stress by measuring strain, and is a measurement method that is not affected by the properties of the film; X-ray diffraction calculates stress by measuring the change in the peak diffraction angle, and is a representative technology for non-destructive measurement of residual stress, but X-ray diffraction and the Stoney formula method cannot detect spherical originals; the ultrasonic method uses the acoustic birefringence effect to obtain and calculate the average stress on the propagation path, which requires a high-precision sound velocity measurement instrument and requires the acoustic elastic characteristic value of the material to be measured in advance, which is another problem. This method has not yet been put into actual measurement. New measurement methods, mainly including the Bahausen noise method, nuclear magnetic resonance method and Raman spectroscopy, are generally complex in experiments, expensive in equipment, limited in suitable measurement scenarios, and develop more slowly.

[0005] In summary, the current residual stress measurement technology of hemispherical resonant gyroscope after metallization coating has many limitations. Whether it is traditional methods or emerging technologies, it is difficult to ensure measurement accuracy while taking into account non-destructive testing and wide applicability. This has become one of the key factors restricting the further improvement of the performance of hemispherical resonant gyroscopes, and the industry urgently needs in-depth research and innovative breakthroughs. Summary of the invention

[0006] The purpose of the present invention is to provide a special adjustment frame for detecting stress of hemispherical resonator coating and a method for detecting stress of hemispherical resonator coating. The special adjustment frame integrates a three-dimensional displacement stage, a two-dimensional displacement stage, and two rotating stages (axial and lateral orientations), thereby realizing precise adjustment of the resonator in multiple dimensions. The surface shape change of the resonator before and after coating is detected by a spherical interferometer, and the surface shape of the resonator is detected again after coating, and then the thermal stress of the resonator coating is calculated using the hemispherical resonator stress calculation formula.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a special adjustment frame for stress detection of hemispherical resonator coating, which is characterized by comprising:

[0009] Three-jaw chuck, used for self-centering, by clamping the rod of the resonator to ensure that the resonator is concentric with the rotating table rotating in the axial direction;

[0010] A rotating table that rotates in an axial direction is installed concentrically with the three-jaw chuck to allow the resonator to rotate in an axial direction;

[0011] A two-dimensional translation stage, mounted on the rotating stage that rotates in a transverse direction, for the rotating stage that rotates in an axial direction to be placed on, and for adjusting the centering of the rotating axis between the resonator and the rotating stage that rotates in a transverse direction;

[0012] A rotating table capable of transverse rotation is mounted on the three-dimensional translation table, for the two-dimensional translation table to be placed, allowing the resonator to rotate in the transverse direction;

[0013] A three-dimensional displacement platform, on which the rotating platform for transverse rotation is placed, for three-dimensional positioning in space;

[0014] Spectral confocal probe 1 and spectral confocal probe 2 measure the absolute position change of the resonator surface, and adjust the two-dimensional translation stage according to the measurement data, with the rotation axis as the origin. When rotating clockwise:

[0015] When the reading of spectral confocal probe 1 decreases and the reading of spectral confocal probe 2 decreases, the center of the oscillator is located in the first quadrant;

[0016] When the reading of spectral confocal probe 1 decreases and the reading of spectral confocal probe 2 increases, the center of the oscillator is located in the second quadrant;

[0017] When the reading of spectral confocal probe 1 increases and the reading of spectral confocal probe 2 increases, the center of the oscillator is located in the third quadrant;

[0018] When the reading of spectral confocal probe 1 increases and the reading of spectral confocal probe 2 decreases, the center of the oscillator is located in the fourth quadrant;

[0019] When the spherical center of the oscillator coincides with the rotation axes of the transverse azimuth rotation stage and the axial azimuth rotation stage, the readings of the spectral confocal probe 1 and the spectral confocal probe 2 do not change significantly.

[0020] Furthermore, the three-jaw chuck can firmly clamp the center rod of the resonator and ensure that the center of the spherical part of the resonator is initially coincident with the rotation axis of the axial azimuth rotation table through the self-centering function.

[0021] Furthermore, by rotating the transverse azimuth rotation stage and using the spectral confocal probe to measure the absolute position change of the resonator surface, the two-dimensional translation stage is adjusted according to the measurement data until the center of the resonator coincides with the rotation axes of the transverse azimuth rotation stage and the axial azimuth rotation stage.

[0022] On the other hand, the present invention also provides a method for detecting the stress of a hemispherical resonator coating using the above-mentioned special adjustment frame, which is characterized in that it comprises the steps of:

[0023] S1. Use a spherical interferometer to detect the surface shape of the uncoated resonator;

[0024] S2. Fixing the resonator on a seven-dimensional adjustment frame, and adjusting the seven-dimensional adjustment frame so that all surfaces of the resonator can be detected by the spherical interferometer;

[0025] S3. After the measurement is completed, a stitching algorithm is used to stitch the measured multiple sub-apertures to reconstruct the complete surface shape of the resonator before coating;

[0026] S4. coating the resonator, repeating the above steps after coating, using the method of steps S1 and S2, using a spherical interferometer and a seven-dimensional adjustment frame to detect the surface shape of the resonator after coating, and reconstructing the complete surface shape of the resonator after coating;

[0027] S5. Compare the surface data before and after coating, and calculate the change in surface shape;

[0028] S6. Apply the hemispherical resonator stress calculation formula, measure the axial deformation of the resonator through an interferometer, and calculate the stress of the resonator based on the axial deformation.

[0029]

[0030] Where P is the film stress on the oscillator, α is the angle corresponding to the total arc length of the spherical shell, and θ i The angle corresponding to the arc length at any point on the arc, R is the radius of the resonator, E is Young's modulus, I is the moment of inertia of the section, which is simplified to a square with the thickness of the resonator as the side length, y θ is the axial deformation at angle θ, measured by the interferometer, and i is the number of pixels measured by the interferometer in the axial direction.

[0031] Further, the step S2 specifically includes:

[0032] Step S2.1: clamp the rod of the resonator on the three-jaw chuck, and ensure that the resonator is concentric with the rotating table rotating in the axial direction;

[0033] Step S2.2 uses spectral confocal probe 1 and spectral confocal probe 2 to measure the absolute position change of the resonator surface, and adjusts the two-dimensional translation stage according to the measurement data, with the rotation axis as the origin. When rotating clockwise:

[0034] When the reading of spectral confocal probe 1 decreases and the reading of spectral confocal probe 2 decreases, the center of the oscillator is located in the first quadrant;

[0035] When the reading of spectral confocal probe 1 decreases and the reading of spectral confocal probe 2 increases, the center of the oscillator is located in the second quadrant;

[0036] When the reading of spectral confocal probe 1 increases and the reading of spectral confocal probe 2 increases, the center of the oscillator is located in the third quadrant;

[0037] When the reading of spectral confocal probe 1 increases and the reading of spectral confocal probe 2 decreases, the center of the oscillator is located in the fourth quadrant;

[0038] When the spherical center of the oscillator coincides with the rotation axes of the transverse azimuth rotation stage and the axial azimuth rotation stage, the readings of the spectral confocal probe 1 and the spectral confocal probe 2 do not change significantly.

[0039] Step S2.3: placing the adjustment frame holding the resonator in the detection area of ​​the spherical interferometer, and adjusting the three-dimensional displacement stage to make the interference fringes reach the optimal state before detection;

[0040] Step S2.4: rotating the rotating stage in the axial direction to detect all sub-apertures in the direction;

[0041] After the detection in step S2.5 is completed, the rotating table for rotating in the transverse direction is rotated, and after the transverse direction is changed, the rotating table for rotating in the axial direction is rotated to perform detection until all surfaces of the resonator are covered;

[0042] Preferably, the output aperture of the spherical interferometer is 100 mm, and the F number of the spherical standard mirror is 1.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1) It integrates a three-dimensional translation stage, a two-dimensional translation stage, and two rotation stages (axial and lateral), which enables precise adjustment of the oscillator in multiple dimensions, not only improving the flexibility of adjustment, but also ensuring the stability and accuracy of the oscillator during the detection process. At the same time, by using a three-jaw chuck as a centering mechanism, the oscillator can be firmly clamped to ensure that it is concentric with the rotation stage rotating in the axial direction, effectively reducing the measurement error caused by improper clamping and improving the accuracy of the detection. Combined with the use of a spectral confocal probe, it can provide real-time feedback during the adjustment process, helping users to quickly and accurately complete the concentricity adjustment of the oscillator and the rotation axis.

[0045] 2) The spherical resonator can be directly tested by using a spherical interferometer without using the patch method, avoiding the need to convert the sphere into a plane for testing, and the resonator can be used directly after testing. Interference testing will not affect the coated resonator, it is a non-destructive test with high testing efficiency. Using the principle of interference detection, interference detection avoids the impact of contact with the test piece on the subsequent use of the test piece.

[0046] 3) During the detection process, the method uses sub-aperture splicing technology to splice the measured sub-apertures to obtain the complete surface shape of the resonator before and after coating. Combined with the surface shape change before and after coating, the stress calculation formula of the hemispherical resonator calculates the stress of the resonator, which can intuitively and accurately reflect the impact of the coating process on the stress of the resonator, providing strong support for the quality control and performance optimization of the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A three-dimensional diagram of a special adjustment frame for stress detection of hemispherical resonator coating according to the present invention;

[0048] Figure 2 This is a usage state diagram of the special adjustment frame for stress detection of hemispherical resonator coating according to the present invention;

[0049] Figure 3 (a) is a schematic diagram of the eccentric rotation of the oscillator.

[0050] Figure 3 (b) is a schematic diagram of deformation before and after coating.

[0051] Figure 4 (a) is the result of stitching after interferometric measurement

[0052] Figure 4(b) is the deformation result diagram before and after coating obtained based on the splicing results.

[0053] Figure 5 The present invention is a flow chart of the method for detecting the stress of the hemispherical resonator coating.

[0054] In the figure: 1-interferometer; 2-spherical standard mirror; 3-resonator; 4-three-jaw chuck; 5-rotating table for axial rotation; 6-two-dimensional translation table; 7-rotating table for lateral rotation; 8-three-dimensional translation table; 9-spectral confocal probe 1; 10-spectral confocal probe 2. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention shall not be limited thereto.

[0056] See also Figure 1-Figure 2 , Figure 1 A three-dimensional diagram of a special adjustment frame for stress detection of hemispherical resonator coating according to the present invention; Figure 2 This is a diagram of the use status of the special adjustment frame for stress detection of hemispherical resonator coating according to the present invention. As shown in the figure, a special adjustment frame for stress detection of hemispherical resonator coating integrates a variety of precision adjustment mechanisms to ensure high-precision positioning and alignment of the resonator during the detection process. Specifically, it includes: a three-jaw chuck 4 for centering, and a rotating table 5 for axial rotation installed concentrically with the three-jaw chuck 4, the rotating table 5 is installed on a two-dimensional displacement table 6; the two-dimensional displacement table 6 is installed on a rotating table 7 for lateral rotation; the two-dimensional displacement table 6 is used for centering the rotation axis of the resonator 3 and the rotating table 7 for lateral rotation, and the bottom layer is a three-dimensional displacement table 8, which is used for spatial three-dimensional positioning of spherical interference detection.

[0057] Measurement process:

[0058] 1. Eccentricity measurement and adjustment:

[0059] After the resonator 3 is clamped by the three-jaw chuck, the rotating table for controlling the lateral orientation of the resonator is first rotated.

[0060] The absolute position of the resonator is measured using a spectral confocal probe. By measuring the eccentricity during rotation, it is possible to accurately determine whether the resonator is eccentric relative to the rotation axis.

[0061] According to the measurement data, adjust the two-dimensional translation stage and gradually reduce the eccentricity of the clamping until the required accuracy is achieved.

[0062] 2. Adjustment of the coincidence between the center of the resonator and the rotation axis:

[0063] The center rod of the oscillator is used as the positioning reference and clamped on the three-jaw chuck to ensure that the center of the oscillator is initially aligned with the rotation axis in the axial direction.

[0064] The absolute position of the resonator surface is measured again using the spectral confocal probe while the rotation stage is rotated in the lateral orientation.

[0065] Due to the presence of the eccentricity and transverse azimuth rotation stage, the absolute position measured by the spectral confocal probe will change. Based on these changes, the eccentricity can be calculated and the two-dimensional translation stage can be adjusted accordingly to make the center of the resonator completely coincide with the rotation axis in the transverse azimuth.

[0066] 3. Final adjustments before interferometry:

[0067] The adjusted seven-dimensional adjustment frame (including a three-dimensional translation stage, a two-dimensional translation stage, two rotation stages and a three-jaw chuck) is placed in the detection area of ​​the spherical interferometer.

[0068] By observing the interference fringes, the three-dimensional translation stage is further adjusted until a zero-fringe state is reached, that is, the resonator surface is completely parallel to the reference plane of the interferometer.

[0069] In this state, sub-aperture detection is performed, and then the rotating table is rotated to gradually complete the detection of the entire surface of the resonator.

[0070] Figure 5 The flowchart of the stress detection method of the hemispherical resonator coating of the present invention is shown in the figure. The method includes the following steps: using the interferometer 1 equipped with the spherical standard mirror 2 to detect the surface shape of the resonator 3 before coating, placing the adjustment frame clamping the resonator 3 in the detection area of ​​the spherical interferometer, adjusting the three-dimensional displacement stage 8 according to the stripes, and adjusting to zero stripes for detection. Rotate the rotating table 5 rotating in the axial azimuth to detect all sub-apertures in the azimuth, and after the detection is completed, rotate the rotating table 7 rotating in the transverse azimuth, and after changing the transverse azimuth, rotate the rotating table 5 rotating in the axial azimuth for detection until all surfaces of the resonator are covered, and splice the measured sub-apertures to obtain the surface shape of the resonator 3 before coating. Coat the resonator 3, repeat the above operation after coating, and obtain the surface shape of the resonator 3 after coating. Obtain the surface shape change of the resonator 3 before and after coating, calculate the stress of the resonator using the hemispherical resonator stress calculation formula, and finally obtain the stress change of the resonator 3 before and after coating.

[0071] In this embodiment, the exit aperture of the spherical interferometer is 100 mm, and the F number of the spherical standard mirror is 1. The resonator 3 is coated by vacuum evaporation, and the vacuum degree is 1.0×10 -3 pa—1.0×10 -4 pa, and the temperature is between 150℃-250℃. The stress of the resonator is calculated using the hemispherical resonator stress calculation formula.

Claims

1. An interferometric measurement mechanism for measuring the axial deformation of a resonator, characterized in that: include: A three-jaw chuck (4) is used for self-centering, and ensures that the resonator (3) is concentric with the rotating table (5) that rotates in the axial direction by clamping the rod of the resonator (3); A rotating table (5) that rotates in an axial direction is installed concentrically with the three-jaw chuck (4) to allow the resonator (3) to rotate in an axial direction; A two-dimensional displacement table (6) is mounted on a rotating table (7) that rotates in a transverse direction, for the rotating table (5) that rotates in an axial direction to be placed on, and is used for centering the rotation axis of the resonator (3) and the rotating table (7) that rotates in a transverse direction; A rotating table (7) capable of rotating in a transverse direction is mounted on a three-dimensional displacement table (8) for placing the two-dimensional displacement table (6) and allowing the resonator (3) to rotate in a transverse direction; A three-dimensional displacement platform (8) for placing the transversely rotating rotation platform (7) and for aligning the spatial position of the resonator during interference measurement; The spectral confocal probe 1 (9) and the spectral confocal probe 2 (10) are aligned with the rotation axis when installed, and the spatial absolute position of the surface of the resonator (3) is detected after the resonator (3) is installed, and real-time feedback is provided when the concentricity of the resonator (3) and the rotation axis is adjusted; After the adjustment is completed, an interferometer (1) equipped with a spherical standard mirror (2) is used to perform interference measurement, and the measurement result is substituted into the hemispherical resonator stress formula to calculate the stress of the hemispherical resonator.

2. The interferometric measurement mechanism for measuring the axial deformation of a resonator according to claim 1, characterized in that: The axial deformation of the resonator is measured by an interferometer, and the stress of the resonator is calculated based on the axial deformation. The formula is as follows: Where P is the film stress on the oscillator, α is the angle corresponding to the total arc length of the spherical shell, and θ i The angle corresponding to the arc length at any point on the arc, R is the radius of the resonator, E is Young's modulus, I is the moment of inertia of the section, which is simplified to a square with the thickness of the resonator as the side length, y θ is the axial deformation at angle θ, measured by the interferometer, and i is the number of pixels measured by the interferometer in the axial direction.

3. The interferometric measurement mechanism for measuring the axial deformation of a resonator according to claim 1, characterized in that: By rotating the lateral azimuth rotation stage (7) and using the spectral confocal probe 1 (9) and the spectral confocal probe 2 (10) to measure the absolute position change of the surface of the resonator (3), the two-dimensional displacement stage (6) is adjusted according to the measurement data, with the rotation axis as the origin, when rotating clockwise: When the reading of the spectral confocal probe 1 (9) decreases and the reading of the spectral confocal probe 2 (10) decreases, the center of the oscillator (3) is located in the first quadrant; When the reading of the spectral confocal probe 1 (9) decreases and the reading of the spectral confocal probe 2 (10) increases, the center of the oscillator (3) is located in the second quadrant; When the reading of the spectral confocal probe 1 (9) increases and the reading of the spectral confocal probe 2 (10) increases, the center of the oscillator (3) is located in the third quadrant; When the reading of the spectral confocal probe 1 (9) increases and the reading of the spectral confocal probe 2 (10) decreases, the center of the oscillator (3) is located in the fourth quadrant; When the center of the oscillator (3) coincides with the rotation axes of the transverse azimuth rotation table (7) and the axial azimuth rotation table (5), the readings of the spectral confocal probe 1 (9) and the spectral confocal probe 2 (10) do not change significantly.

4. A method for detecting the stress of a hemispherical resonator coating using the interferometric measurement mechanism for measuring the axial deformation of a resonator as described in any one of claims 1 to 3, characterized in that: Includes steps: S1. Use a spherical interferometer to detect the surface shape of the uncoated resonator; S2. Fixing the resonator on a seven-dimensional adjustment frame, and adjusting the seven-dimensional adjustment frame so that all surfaces of the resonator can be detected by the spherical interferometer; S3. After the measurement is completed, a stitching algorithm is used to stitch the measured multiple sub-apertures to reconstruct the complete surface shape of the resonator before coating; S4. coating the resonator, repeating the above steps after coating, using the method of steps S1 and S2, using a spherical interferometer and a seven-dimensional adjustment frame to detect the surface shape of the resonator after coating, and reconstructing the complete surface shape of the resonator after coating; S5. Compare the surface data before and after coating, and calculate the change in surface shape; S6. The stress of the hemispherical resonator is calculated by substituting the actually measured surface shape change into the hemispherical resonator stress calculation formula.

5. The method for detecting stress of hemispherical resonator coating according to claim 4, characterized in that: The step S2 specifically includes: Step S2.1: clamp the rod of the resonator (3) on the three-jaw chuck (4), and ensure that the resonator (3) is concentric with the rotating table (5) that rotates in the axial direction; Step S2.2: using a spectral confocal probe (9) to detect the absolute spatial position of the surface of the resonator (3), and rotating the rotating stage (7) for lateral rotation to observe the change of the spatial position of the surface of the resonator, and adjusting the two-dimensional displacement stage (6) according to the detection result until the spatial position of the surface of the resonator (3) does not change significantly during the rotation, thereby completing the concentric adjustment; Step S2.3: placing the adjustment frame holding the resonator (3) in the detection area of ​​the spherical interferometer (1), and adjusting the three-dimensional displacement stage (8) to make the interference fringes reach an optimal state before detection; Step S2.4: rotating the rotating table (5) in the axial direction to detect all sub-apertures in the direction; After the detection in step S2.5 is completed, the rotating table (7) that rotates in the transverse direction is rotated, and after the transverse direction is changed, the rotating table (5) that rotates in the axial direction is rotated to perform detection until all surfaces of the resonator are covered.

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