Hemispherical harmonic oscillator surface roughness in-situ measurement method based on white light interferometer

Abstract

The invention discloses a hemispherical harmonic oscillator surface roughness in-situ measurement method based on a white light interferometer, relates to the technical field of ultra-precision grinding and polishing processing, and aims to solve the problems that in an existing method, a hemispherical harmonic oscillator needs to be taken down from a processing machine tool for roughness measurement, when the surface roughness is large, re-processing is needed, and the processing time is shortened. And the machining precision of the hemispherical harmonic oscillator is seriously influenced by repeated clamping errors. The method is based on a position measurement system of an ultra-precision grinding and polishing machine tool integrating a white light interferometer and a hemispherical harmonic oscillator, and comprises the following steps: firstly, measuring a complete outer surface area of the hemispherical harmonic oscillator by adopting a white light interference measuring head, and splicing all sub-apertures according to a sub-aperture splicing algorithm; obtaining a surface roughness distribution result of the outer surface area of the hemispherical harmonic oscillator; and then the surface roughness of the end face of the hemispherical resonator in the circumferential direction is measured through a white light interference measuring head, all sub-apertures are spliced according to a sub-aperture splicing algorithm, and the surface roughness distribution of the end face of the hemispherical resonator is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-precision grinding and polishing, and in particular to an on-site measurement method for the surface roughness of a hemispherical resonator based on a white light interferometer. Background Art

[0002] The hemispherical resonator gyroscope (HRG) is currently the most accurate solid-state vibratory gyroscope. It is considered a disruptive technology and is the gyroscope most likely to rival or even replace optical gyroscopes in the future. It can meet the long-endurance development needs of the new generation of inertial devices and offers advantages such as ultra-high precision, high reliability, and a long lifespan. The core component of the HRG is the resonator, a thin-walled hemispherical shell that flexes under the action of force electrodes, forming standing waves. The Coriolis effect of the standing waves under external rotational excitation causes the vibration mode to precess. The angular velocity can be measured by detecting the vibration mode information using the pickup electrodes.

[0003] The hemispherical resonator requires that the mass be evenly distributed about the rotating axis, because any uneven mass distribution will cause the frequency of the resonator to split, reducing the accuracy of the gyroscope. The even mass distribution requires that the surface roughness of the hemispherical shell be small, so the surface quality accuracy of the processing is very high. However, the traditional process is limited by the accuracy of the machine tool, and the errors are relatively large. At the same time, there is a lack of on-site detection means for roughness errors. The current main method for measuring the surface roughness of a hemispherical resonator is to remove the hemispherical resonator from the processing machine tool and measure it on an independent white light interferometer. When the surface roughness is found to be large, it needs to be reprocessed. Repeated clamping errors will greatly affect the performance of the hemispherical resonator. Therefore, there is an urgent need to innovate on-site measurement methods for the surface roughness of hemispherical resonators. Summary of the Invention

[0004] The technical problems to be solved by the present invention are:

[0005] The existing method requires the hemispherical resonator to be removed from the processing machine tool for roughness measurement. When the surface roughness is found to be large, it needs to be reprocessed, and the repeated clamping error seriously affects the processing accuracy of the hemispherical resonator.

[0006] The present invention is to solve the above technical problems using the following technical solutions:

[0007] The present invention provides an in-situ measurement method for the surface roughness of a hemispherical resonator based on a white light interferometer. The method is based on an in-situ measurement system integrating a white light interferometer and a hemispherical resonator ultra-precision grinding and polishing machine tool, and includes the following steps:

[0008] The measurement of the surface roughness of the outer spherical surface of the S100 hemispherical shell includes the following steps:

[0009] S110. For an in-situ hemispherical resonator that has been ultra-precision ground or magnetorheologically polished, adjust the Z-axis linear motion stage so that the measuring optical axis of the white-light interferometer probe and the center of the hemispherical resonator are at the same horizontal height. Adjust the C-axis turntable so that the measuring optical axis of the white-light interferometer probe is perpendicular to the outer spherical surface of the hemispherical shell of the hemispherical resonator. Control the X-axis linear motion stage and the Y-axis linear motion stage to adjust the distance between the white-light interferometer probe and the lip edge of the outer spherical surface of the hemispherical shell of the hemispherical resonator so that the interference fringes appear clear and high-contrast.

[0010] S120, defining the workpiece spindle position as the initial measurement position of the hemispherical resonator, rotating the workpiece spindle by an angle, and measuring the surface roughness of one sub-aperture of the hemispherical resonator using a white light interferometer probe until the hemispherical resonator rotates one circumferential direction, obtaining the circumferential surface roughness distribution result of the lip edge position of the outer spherical surface of the hemispherical shell;

[0011] S130, rotating the white light interferometer probe toward the high latitude of the hemispherical resonator via the C-axis turntable, and measuring the surface roughness of the sub-aperture of the hemispherical resonator at the latitude via the white light interferometer probe;

[0012] S140, repeating steps S120-S130 until the white light interferometer probe measures the outer surface area of ​​the complete hemispherical resonator;

[0013] S150, stitching all sub-apertures according to a sub-aperture stitching algorithm to obtain a surface roughness distribution result of an outer surface area of ​​the hemispherical resonator;

[0014] The measurement of the surface roughness of the S200 hemispherical shell end face includes the following steps:

[0015] S210. Adjust the Z-axis linear motion platform so that the measuring optical axis of the white light interferometer probe and the axis of the hemispherical resonator support rod are at the same horizontal height. Adjust the C-axis turntable so that the measuring optical axis of the white light interferometer probe is perpendicular to the end surface of the hemispherical shell of the hemispherical resonator. Control the X-axis linear motion platform and the Y-axis linear motion platform to adjust the distance between the white light interferometer probe and the end surface of the hemispherical shell of the hemispherical resonator so that the interference fringes appear clear and high-contrast.

[0016] S220, defining the workpiece spindle position as the initial measurement position of the hemispherical resonator, rotating the workpiece spindle by one angle, and measuring the surface roughness of one sub-aperture of the end face of the hemispherical resonator by a white light interferometer probe until the hemispherical resonator rotates one circumference;

[0017] S230 , stitching all sub-apertures together according to a sub-aperture stitching algorithm to obtain a surface roughness distribution of the end face of the hemispherical resonator.

[0018] Furthermore, the sub-aperture stitching algorithm comprises the following steps:

[0019] Move all sub-apertures from the local coordinate system to the global coordinate system. The measurement data of the sub-aperture of the white light interferometer is (x, y, z), where (x, y) is the horizontal and vertical coordinates on the image plane, and z is the height value. The measurement data of the kth sub-aperture is (x k ,y k ,z k ), the measurement data of the t-th sub-aperture is (x t ,y t ,z t );

[0020]

[0021] Among them, g is the pose transformation matrix, (x q ,y q , z q ) is the coordinate point of the hemispherical resonator subaperture data in the global coordinate system;

[0022] In the global coordinate system, the measurement data deviation in the sub-aperture overlapping area is:

[0023] d=<(x k ,y k , z k )-q,n>-<(x t ,y t , z t )-q,n> (2)

[0024] Where {q} is the point set of the projection of the mesoaperture measurement data onto the surface of the hemispherical resonator, and n is the unit normal vector of the hemispherical resonator surface at position q; <(x k ,y k , z k )-q,n> is a vector (x k ,y k , z k )-the inner product of q and vector n, <(x t ,y t ,z t )-q, n> is a vector (x t ,y t ,z t )-the inner product of q and vector n;

[0025] Based on the least squares method, the measurement data deviation of the sub-aperture overlapping area is minimized to obtain the surface roughness result of the hemispherical resonator;

[0026]

[0027] Among them, N o is the total number of overlapping point pairs.

[0028] Furthermore, the method for determining the center of the hemispherical resonator in S110 is:

[0029] Install the small ball-end grinding wheel on the tool spindle, and adjust the U-axis micro-displacement platform so that the center of the small ball-end grinding wheel remains stationary when the C-axis turntable rotates; make the small ball-end grinding wheel touch the outer spherical surface of the hemispherical shell of the hemispherical resonator close to the lip position point m1 and the transition fillet position point m2 respectively, and draw a vertical line at the midpoint m3 of the line connecting positions m1 and m2. The intersection of the vertical line and the rotation axis of the hemispherical resonator is the center position of the hemispherical resonator in the machine tool coordinate system.

[0030] Furthermore, the overlapping area between adjacent sub-apertures in S120 is greater than 1 / 4.

[0031] Furthermore, the in-situ measurement system includes: a hemispherical resonator ultra-precision grinding and polishing machine tool and a white light interferometer, and the hemispherical resonator ultra-precision grinding and polishing machine tool includes: a machine tool bed, an X-axis linear motion platform, a Y-axis linear motion platform, a Z-axis linear motion platform, a C-axis turntable, a U-axis micro-displacement platform, a workpiece spindle, a tool spindle, a triangular connecting frame, a fixed frame and a workbench;

[0032] An X-axis linear motion platform, a Y-axis linear motion platform, and a Z-axis linear motion platform are installed on the machine tool bed. The X-axis linear motion platform and the Y-axis linear motion platform are stacked in a cross shape, and the Z-axis linear motion platform is installed perpendicular to the X-axis linear motion platform and the Y-axis linear motion platform, together forming a spatial rectangular coordinate system;

[0033] The workbench is mounted on an X-axis linear motion platform and a Y-axis linear motion platform;

[0034] The workpiece spindle is installed on the workbench, and the direction of the rotation axis is parallel to the Y axis;

[0035] The C-axis turntable is mounted on the Z-axis linear motion platform via a triangular connecting frame, and the direction of the rotation axis is parallel to the Z-axis;

[0036] The U-axis micro-displacement platform is mounted on the C-axis turntable;

[0037] The tool spindle and white light interferometer are mounted on a U-axis micro-displacement platform through a fixing frame, wherein the angle between the tool spindle and the U-axis micro-displacement platform is 40°, and the white light interferometer probe is perpendicular to the axis of the U-axis micro-displacement platform.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The present invention integrates a white light interferometer on a hemispherical resonator ultra-precision grinding and polishing machine tool, and measures the surface roughness of the hemispherical resonator based on the white light interferometer, thereby realizing the detection of the surface roughness error of the hemispherical resonator at any time during the ultra-precision polishing of the hemispherical resonator.

[0040] 2. The method of the present invention detects the surface roughness of the hemispherical resonator in a non-contact manner, thereby avoiding the risk of damaging the processed surface of the hemispherical resonator.

[0041] 3. The on-site surface roughness detection results of the present invention can guide the writing of polishing numerical control programs to achieve quality consistency of the hemispherical resonator.

[0042] 4. The method of the present invention can measure the axial surface roughness distribution of a hemispherical resonator at different latitudes based on a white light interferometer probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the low, medium and high latitude sub-aperture measurement positions on the outer surface of a hemispherical resonator in an embodiment of the present invention;

[0044] Figure 2 A diagram showing the position of the center of a hemispherical resonator in a machine tool coordinate system determined by tool setting in an embodiment of the present invention;

[0045] Figure 3 Schematic diagram of the sub-aperture measurement position of the end face of a hemispherical resonator in an embodiment of the present invention;

[0046] Figure 4 This is an isometric view of an in-situ measurement platform for the surface roughness of a hemispherical resonator based on a white light interferometer in an embodiment of the present invention;

[0047] Figure 5 This is a motion system for measuring the surface roughness of the outer surface of a hemispherical resonator in an embodiment of the present invention.

[0048] Description of reference numerals:

[0049] 1-Machine tool bed, 11-X-axis linear motion platform, 12-Y-axis linear motion platform, 13-Z-axis linear motion platform, 14-C-axis turntable, 15-U-axis micro-displacement platform, 16-Workpiece spindle, 17-Polishing spindle, 2-Triangular connecting frame, 3-Fixed frame, 4-Workbench, 5-SuperView WX100 series white light interferometer probe. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the present invention, exemplary embodiments or examples of the present invention will be described below with reference to the accompanying drawings. Obviously, the described embodiments or examples are only some of the embodiments or examples of the present invention, and not all of them. Based on the embodiments or examples of the present invention, all other embodiments or examples obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0052] Specific implementation plan 1: Combined Figures 1 to 4 As shown, the present invention provides an in-situ measurement method for the surface roughness of a hemispherical resonator based on a white light interferometer. The method is based on an in-situ measurement system integrating a white light interferometer and a hemispherical resonator ultra-precision grinding and polishing machine tool, and includes the following steps:

[0053] The measurement of the surface roughness of the outer spherical surface of the S100 hemispherical shell includes the following steps:

[0054] S110. For an in-situ hemispherical resonator that has been ultra-precision ground or magnetorheologically polished, adjust the Z-axis linear motion platform 13 so that the measuring optical axis of the white-light interferometer probe and the center of the hemispherical resonator are at the same horizontal height. Adjust the C-axis turntable 14 so that the measuring optical axis of the white-light interferometer probe is perpendicular to the outer spherical surface of the hemispherical shell of the hemispherical resonator. Control the X-axis linear motion platform 11 and the Y-axis linear motion platform 12 to adjust the distance between the white-light interferometer probe and the lip edge of the outer spherical surface of the hemispherical shell of the hemispherical resonator so that the interference fringes appear clear and high-contrast.

[0055] S120, such as Figure 1 As shown in the figure, the C-axis turntable is at the 0° position, the position of the workpiece spindle 16 is defined as the initial measurement position of the hemispherical resonator, the workpiece spindle 16 rotates 5°, the lip edge of the outer spherical surface of the hemispherical shell is circumferentially divided into 72 sub-apertures, and the surface roughness of one sub-aperture of the hemispherical resonator is measured by the white light interferometer probe. When the hemispherical resonator rotates one circumference, the circumferential surface roughness distribution result of the lip edge of the outer spherical surface of the hemispherical shell is obtained;

[0056] S130, assuming that the rotation direction of the hemispherical resonator in the high-latitude direction is a positive direction, the white light interferometer probe is rotated 25° in the high-latitude direction of the hemispherical resonator via the C-axis turntable 14, and the surface roughness of the sub-aperture of the hemispherical resonator at this latitude is measured via the white light interferometer probe;

[0057] S140, repeating steps S120-S130 until the white light interferometer probe measures the outer surface area of ​​the complete hemispherical resonator;

[0058] S150, stitching all sub-apertures according to a sub-aperture stitching algorithm to obtain a surface roughness distribution result of an outer surface area of ​​the hemispherical resonator;

[0059] S200 hemispherical shell end surface roughness measurement, such as Figure 3 As shown, the following steps are included:

[0060] S210, adjust the Z-axis linear motion platform 13 so that the measuring optical axis of the white light interferometer probe and the axis of the hemispherical resonator support rod are at the same horizontal height, adjust the C-axis turntable 14 so that the measuring optical axis of the white light interferometer probe is perpendicular to the end surface of the hemispherical shell of the hemispherical resonator, and control the X-axis linear motion platform 11 and the Y-axis linear motion platform 12 to adjust the distance between the white light interferometer probe and the end surface of the hemispherical shell of the hemispherical resonator so that the interference fringes appear clear and high-contrast;

[0061] S220, the C-axis turntable 14 is at the 0° position, and the position of the workpiece spindle 16 at this time is defined as the initial measurement position of the hemispherical resonator. The workpiece spindle 16 rotates 5°, and the lip edge position of the hemispherical shell end surface is divided into 40 sub-apertures in the circumferential direction. The surface roughness of one sub-aperture of the hemispherical resonator end surface is measured by the white light interferometer probe until the hemispherical resonator rotates one circumferential direction.

[0062] S230 , stitching all sub-apertures together according to a sub-aperture stitching algorithm to obtain a surface roughness distribution of the end face of the hemispherical resonator.

[0063] Specific implementation scheme 2: The sub-aperture stitching algorithm includes the following steps:

[0064] The global coordinate system O-XYZ of the hemispherical resonator is established at the top of the hemispherical shell, where the Z axis coincides with the axis of the central support rod of the hemispherical resonator. The local coordinate system O-UVW of the subaperture is established at the center of the subaperture, where the W axis is perpendicular to the subaperture plane. All subapertures are transferred from the local coordinate system to the global coordinate system. The measurement data of the subaperture of the white light interferometer 5 is (x, y, z), where (x, y) is the horizontal coordinate and vertical coordinate on the image plane, and z is the height value; the measurement data of the kth subaperture is (x k ,y k ,z k ), the measurement data of the t-th sub-aperture is (x t ,y t ,z t );

[0065]

[0066] Among them, g is the pose transformation matrix, (x q ,y q , z q) is the coordinate point of the hemispherical resonator subaperture data in the global coordinate system;

[0067] In the global coordinate system, the measurement data deviation in the sub-aperture overlapping area is:

[0068] d=<(x k ,y k , z k )-q,n>-<(x t ,y t , z t )-q,n> (2)

[0069] Where {q} is the point set of the projection of the mesoaperture measurement data onto the surface of the hemispherical resonator, and n is the unit normal vector of the hemispherical resonator surface at position q; <(x k ,y k , z k )-q,n> is a vector (x k ,y k , z k )-the inner product of q and vector n, <(x t ,y t ,z t )-q, n> is a vector (x t ,y t ,z t )-the inner product of q and vector n;

[0070] Based on the least squares method, the measurement data deviation of the sub-aperture overlapping area is minimized to obtain the surface roughness result of the hemispherical resonator;

[0071]

[0072] Among them, N o The rest of this implementation is the same as the first implementation.

[0073] Specific implementation plan three: S110 includes the following steps:

[0074] S111: Adjust the X-axis linear motion platform 11 and the Y-axis linear motion platform 12 so that the center of the hemispherical resonator coincides with the rotation axis of the C-axis turntable 14; adjust the Z-axis linear motion platform 13 so that the optical axis of the white light interferometer probe and the center of the hemispherical resonator are at the same height;

[0075] S112, ensuring that the optical axis of the white light interferometer probe intersects perpendicularly with the axis of the C-axis turntable 14 by means of the assembly accuracy of the fixed frame 3 and the fine adjustment position of the U-axis micro-displacement platform 15;

[0076] S113. Adjust the C-axis turntable 14 so that the measuring optical axis of the white light interferometer probe is perpendicular to the outer spherical surface of the hemispherical shell of the hemispherical resonator. Control the X-axis linear motion platform 11 and the Y-axis linear motion platform 12 to adjust the distance between the white light interferometer probe and the lip edge of the outer spherical surface of the hemispherical shell of the hemispherical resonator so that the interference fringes appear clear and high-contrast. This embodiment is otherwise identical to Specific Embodiment 2.

[0077] Specific implementation plan four: Figure 2 As shown, the method for determining the center of the hemispherical resonator in S111 is:

[0078] A small ball-end grinding wheel is mounted on the tool spindle. The U-axis micro-displacement platform 15 is adjusted to keep the center of the small ball-end grinding wheel stationary while the C-axis turntable 14 rotates. The small ball-end grinding wheel is positioned on the outer surface of the hemispherical shell of the hemispherical resonator, near the lip edge position m1 and near the transition fillet position m2. A vertical line is drawn through the midpoint m3 of the line connecting positions m1 and m2. The intersection of the vertical line and the axis of rotation of the hemispherical resonator is the center position of the hemispherical resonator in the machine tool coordinate system. The rest of this implementation is the same as the third implementation.

[0079] Specific implementation scheme 5: In S120, the overlapping area between adjacent sub-apertures is greater than 1 / 4. The rest of this implementation scheme is the same as that of the specific implementation scheme 4.

[0080] Specific implementation scheme six: The method adopts an in-situ measurement system of a hemispherical resonator ultra-precision grinding and polishing machine tool, such as Figure 4 and Figure 5 As shown, the in-situ measurement system includes: a hemispherical resonator ultra-precision grinding and polishing machine tool and a white light interferometer 5, the hemispherical resonator ultra-precision grinding and polishing machine tool includes: a machine tool bed 1, an X-axis linear motion platform 11, a Y-axis linear motion platform 12, a Z-axis linear motion platform 13, a C-axis turntable 14, a U-axis micro-displacement platform 15, a workpiece spindle 16, a tool spindle 17, a triangular connecting frame 2, a fixed frame 3 and a workbench 4;

[0081] An X-axis linear motion platform 11, a Y-axis linear motion platform 12, and a Z-axis linear motion platform 13 are installed on the machine tool bed 1. The X-axis linear motion platform 11 and the Y-axis linear motion platform 12 are stacked in a cross shape, and the Z-axis linear motion platform 13 is installed perpendicular to the X-axis linear motion platform 11 and the Y-axis linear motion platform 12, together forming a spatial rectangular coordinate system.

[0082] The workbench 4 is mounted on an X-axis linear motion platform 11 and a Y-axis linear motion platform 12;

[0083] The workpiece spindle 16 is mounted on the workbench 4, and the direction of the rotation axis is parallel to the Y axis;

[0084] The C-axis turntable 14 is mounted on the Z-axis linear motion platform 13 via the triangular connecting frame 2, and the direction of the rotation axis is parallel to the Z-axis;

[0085] The U-axis micro-displacement platform 15 is installed on the C-axis turntable 14;

[0086] The tool spindle 17 and the white light interferometer 5 are mounted on the U-axis micro-displacement platform 15 via a fixing frame 3 , wherein the angle between the tool spindle 17 and the U-axis micro-displacement platform 15 is 40°, and the white light interferometer probe is perpendicular to the axis of the U-axis micro-displacement platform 15 .

[0087] White light interferometer 5 uses the SuperView WX100 series white light interferometer probe. This non-contact precision optical probe is developed based on white light interferometry and precision scanning. It primarily consists of an optical interferometer system and a Z-scanning system. Using a 5x objective lens, it offers a field of view of 1.96mm × 1.96mm at 0.5x magnification, a measurable slope limit of 7.4°, and a 10mm vertical scanning range achieved through a glass grating scale, a subdivision device, and a DC motor. The repeatability of step height measurement is less than 0.1%. This embodiment is otherwise identical to Specific Embodiment 5.

[0088] Although the present invention is disclosed as above, the scope of protection disclosed by the present invention is not limited thereto. Those skilled in the art of the present invention may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for measuring the surface roughness of a hemispherical resonator based on a white light interferometer, characterized in that: The method is based on a position measurement system integrating a white light interferometer and a hemispherical resonator ultra-precision grinding and polishing machine tool, and includes the following steps: The measurement of the surface roughness of the outer spherical surface of the S100 hemispherical shell includes the following steps: S110, for an in-situ hemispherical resonator after ultra-precision grinding or magnetorheological polishing, adjust the Z-axis linear motion platform (13) so that the measuring optical axis of the white light interferometer probe and the center of the hemispherical resonator are at the same horizontal height, adjust the C-axis turntable (14) so ​​that the measuring optical axis of the white light interferometer probe is perpendicular to the outer spherical surface of the hemispherical shell of the hemispherical resonator, control the X-axis linear motion platform (11) and the Y-axis linear motion platform (12) to adjust the distance between the white light interferometer probe and the lip edge of the outer spherical surface of the hemispherical shell of the hemispherical resonator, so that the interference fringes are clear and high-contrast; S120, defining the position of the workpiece spindle (16) as the initial measurement position of the hemispherical resonator, rotating the workpiece spindle (16) by an angle, measuring the surface roughness of one sub-aperture of the hemispherical resonator by a white light interferometer probe, and obtaining the circumferential surface roughness distribution result of the lip edge position of the outer spherical surface of the hemispherical shell until the hemispherical resonator rotates one circumference; S130, rotating the white light interferometer probe toward the high latitude direction of the hemispherical resonator via the C-axis turntable (14), and measuring the surface roughness of the sub-aperture of the hemispherical resonator at the latitude via the white light interferometer probe; S140, repeating steps S120-S130 until the white light interferometer probe measures the outer surface area of ​​the complete hemispherical resonator; S150, stitching all sub-apertures according to a sub-aperture stitching algorithm to obtain a surface roughness distribution result of an outer surface area of ​​the hemispherical resonator; The measurement of the surface roughness of the S200 hemispherical shell end face includes the following steps: S210, adjusting the Z-axis linear motion platform (13) so that the measuring optical axis of the white light interferometer probe and the axis of the hemispherical resonator support rod are at the same horizontal height, adjusting the C-axis turntable (14) so ​​that the measuring optical axis of the white light interferometer probe is perpendicular to the end face of the hemispherical shell of the hemispherical resonator, and controlling the X-axis linear motion platform (11) and the Y-axis linear motion platform (12) to adjust the distance between the white light interferometer probe and the end face of the hemispherical shell of the hemispherical resonator so that the interference fringes are clear and high-contrast; S220, defining the position of the workpiece spindle (16) as the initial measurement position of the hemispherical resonator, rotating the workpiece spindle (16) by one angle, and measuring the surface roughness of one sub-aperture of the end face of the hemispherical resonator by a white light interferometer probe until the hemispherical resonator rotates one circumference; S230 , stitching all sub-apertures together according to a sub-aperture stitching algorithm to obtain a surface roughness distribution of the end face of the hemispherical resonator.

2. The in-situ measurement method for the surface roughness of a hemispherical resonator based on a white light interferometer according to claim 1 is characterized in that: The sub-aperture stitching algorithm comprises the following steps: All sub-apertures are moved from the local coordinate system to the global coordinate system. The measurement data of the sub-aperture of the white light interferometer (5) is (x, y, z), where (x, y) is the horizontal coordinate and vertical coordinate on the image plane, and z is the height value; the measurement data of the kth sub-aperture is (x k ,y k ,z k ), the measurement data of the t-th sub-aperture is (x t ,y t ,z t ); Among them, g is the pose transformation matrix, (x q ,y q , z q ) is the coordinate point of the hemispherical resonator subaperture data in the global coordinate system; In the global coordinate system, the measurement data deviation in the sub-aperture overlapping area is: d=<(x k ,y k ,z k )-q,n>-<(x t ,y t ,z t )-q,n> (2) Where {q} is the point set of the projection of the mesoaperture measurement data onto the surface of the hemispherical resonator, and n is the unit normal vector of the hemispherical resonator surface at position q; <(x k ,y k , z k )-q,n> is a vector (x k ,y k ,z k )-the inner product of q and vector n, <(x t ,y t ,z t )-q, n> is a vector (x t ,y t ,z t )-the inner product of q and vector n; Based on the least squares method, the measurement data deviation of the sub-aperture overlapping area is minimized to obtain the surface roughness result of the hemispherical resonator; Among them, N o is the total number of overlapping point pairs.

3. The in-situ measurement method of the surface roughness of a hemispherical resonator based on a white light interferometer according to claim 2 is characterized in that: The method for determining the center of the hemispherical resonator in S110 is: A small ball-end grinding wheel is mounted on the tool spindle, and the center of the small ball-end grinding wheel is kept stationary when the C-axis turntable (14) rotates by adjusting the U-axis micro-displacement platform (15); the small ball-end grinding wheel is made to touch the outer spherical surface of the hemispherical shell of the hemispherical resonator, which is close to the lip position point m1 and the transition fillet position point m2 respectively, and a vertical line is drawn at the midpoint m3 of the line connecting the positions m1 and m2. The intersection of the vertical line and the rotation axis of the hemispherical resonator is the center position of the hemispherical resonator in the machine tool coordinate system.

4. The in-situ measurement method of surface roughness of a hemispherical resonator based on white light interferometer according to claim 3 is characterized in that: The overlapping area between adjacent sub-apertures in S120 is greater than 1 / 4.

5. The on-site measurement method for surface roughness of a hemispherical resonator based on white light interferometer according to claim 4 is characterized in that: The in-situ measurement system comprises: a hemispherical resonator ultra-precision grinding and polishing machine tool and a white light interferometer (5); the hemispherical resonator ultra-precision grinding and polishing machine tool comprises: a machine bed (1), an X-axis linear motion platform (11), a Y-axis linear motion platform (12), a Z-axis linear motion platform (13), a C-axis turntable (14), a U-axis micro-displacement platform (15), a workpiece spindle (16), a tool spindle (17), a triangular connecting frame (2), a fixed frame (3) and a workbench (4); An X-axis linear motion platform (11), a Y-axis linear motion platform (12), and a Z-axis linear motion platform (13) are installed on the machine tool bed (1); the X-axis linear motion platform (11) and the Y-axis linear motion platform (12) are installed in a cross-stacked manner; and the Z-axis linear motion platform (13) is installed perpendicular to the X-axis linear motion platform (11) and the Y-axis linear motion platform (12), together forming a spatial rectangular coordinate system. The workbench (4) is mounted on an X-axis linear motion platform (11) and a Y-axis linear motion platform (12); The workpiece spindle (16) is mounted on the workbench (4), and the direction of the rotation axis is parallel to the Y axis; The C-axis turntable (14) is mounted on the Z-axis linear motion platform (13) via a triangular connecting frame (2), and the direction of the rotation axis is parallel to the Z axis; The U-axis micro-displacement platform (15) is installed on the C-axis turntable (14); The tool spindle (17) and the white light interferometer (5) are mounted on a U-axis micro-displacement platform (15) via a fixing frame (3), wherein the angle between the tool spindle (17) and the U-axis micro-displacement platform (15) is 40°, and the white light interferometer probe is perpendicular to the axis of the U-axis micro-displacement platform (15).

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