Calibration method of turntable shaft and its encoder

Abstract

The present application discloses a method for calibrating a turntable shaft and its encoder, which belongs to the field of precision instrument technology. The present application combines means and operations such as a fluorescence microscope with astigmatism imaging function, a precision translation stage and spatial coordinate solution, and realizes a method for simultaneously calibrating the accuracy of any angle point, shaft diameter jump and yaw and pitch vibration angle of the turntable encoder within the full cycle, without adding additional instruments and devices, thereby realizing full-cycle calibration of the accuracy of the encoder assembled on a high-precision turntable and the posture of the shaft, laying the necessary technical foundation for improving the accuracy and stability of the turntable, and is easy to operate.

Description

Technical Field

[0001] The present application relates to the field of precision instruments, and in particular to a calibration method for a turntable shaft and an encoder thereof. Background Art

[0002] High-precision turntables are not only core technologies in precision engineering, but their development will directly boost the advancement of key industries such as semiconductors, aerospace, and biomedical technology. They also provide fundamental support for scenarios like smart factories and future laboratories, possessing far-reaching value. The encoder's resolution accuracy, as well as the impact of shaft runout and vibration during rotation after assembly, constantly impact the turntable's rotational accuracy. Therefore, calibration of the turntable with the encoder installed is essential. Currently, the most commonly used calibration method for turntable encoders is based on the metrology technical specification JJF1115-2004, which uses a combination of a polyhedron and an autocollimator. This method verifies the circular grating encoder's error at equally spaced angular measurement points, calibrating the encoder error within these intervals to a single value. Therefore, this method does not strictly calibrate any angle within the full period of the circular grating. Furthermore, if shaft runout and yaw and pitch vibration are also required, additional instrument transposition is required, making it less convenient to operate. Summary of the Invention

[0003] The present application aims to provide a method for simultaneously calibrating the accuracy of any angle point, shaft diameter runout, and yaw and pitch vibration angles of a turntable encoder within a full cycle in response to the above-mentioned problems.

[0004] To achieve the above objectives, the technical solution of this application is:

[0005] A method for calibrating a turntable shaft and its encoder, comprising:

[0006] An objective lens, a charge coupled image sensor, a cylindrical lens and a fluorescence excitation light source are used to form a fluorescence microscope with astigmatism imaging function and a fixed spatial position.

[0007] Three fluorescent microspheres are fixed on a flat substrate so that the three fluorescent microspheres are imaged on a charge-coupled image sensor;

[0008] Based on the imaging of each fluorescent microsphere, the respective XY axis width ratio is obtained to determine a longitudinal object plane and a normal vector of the longitudinal object plane of the fluorescence microscope;

[0009] The microscopic magnification function of each fluorescent microsphere is obtained according to the functional relationship between the longitudinal object plane height function and the XY axis width ratio of each fluorescent microsphere;

[0010] Start the calibrated turntable to ensure that each fluorescent microsphere can be imaged on the charge-coupled image sensor during one rotation of the turntable axis;

[0011] The spatial plane coordinate value of each fluorescent microsphere mapped to the imaging plane coordinate of the charge coupled image sensor is obtained according to the microscopic magnification function and the imaging centroid coordinate of each fluorescent microsphere, and a plane ellipse function fitting is performed to determine that the rotation axis of the turntable is parallel to the imaging optical axis of the fluorescence microscope;

[0012] At the start moment of the turntable axis rotation, the spatial three-dimensional coordinate value of each fluorescent microsphere is obtained according to the spatial plane coordinate value of each fluorescent microsphere and the longitudinal object plane height function value, and the angle between the substrate plane and the X axis of the spatial coordinate system of the fluorescent microsphere and the angle between the substrate plane and the Y axis of the spatial coordinate system of the fluorescent microsphere are obtained;

[0013] When the turntable shaft rotates, calibration data for the accuracy of the turntable encoder within a complete rotation cycle is obtained based on the fitted ellipse and the angle value of each turntable shaft rotation step angle encoder; radial runout data within a complete rotation cycle of the turntable shaft is obtained based on the spatial plane coordinate value of each fluorescent microsphere and the center of the fitted ellipse; axial runout data within a complete rotation cycle of the turntable shaft is obtained based on the spatial three-dimensional coordinate value of each fluorescent microsphere; calibration data for the yaw and pitch vibration angles within a complete rotation cycle are obtained based on the angles between the substrate plane and the X-axis and the angles between the substrate plane and the Y-axis.

[0014] Optionally, the fluorescence microscope with astigmatism imaging function that is fixed in spatial position by using an objective lens, a charge-coupled image sensor, a cylindrical lens and a fluorescence excitation light source comprises: placing the cylindrical lens between the objective lens and the charge-coupled image sensor, the bottom surface of the cylindrical lens is parallel to the charge-coupled image sensor, and the edge where the semicircular cross-section of the cylindrical lens intersects with the bottom surface of the cylindrical lens is parallel to the X-axis direction of the imaging surface of the charge-coupled image sensor, the normal vector of the charge-coupled image sensor is parallel to the imaging optical axis of the objective lens, the outer side of the objective lens is covered with a fluorescence excitation light source, and after the fluorescence excitation light source is turned on, the excitation light beam is incident on the spatial area under the objective lens; the objective lens, the charge-coupled image sensor, the cylindrical lens and the fluorescence excitation light source constitute the fluorescence microscope with astigmatism imaging function that is fixed in spatial position.

[0015] Optionally, the three fluorescent microspheres are fixed on a planar substrate so that the three fluorescent microspheres are imaged on a charge-coupled image sensor, including: fixing the three fluorescent microspheres on a planar substrate, the three fluorescent microspheres are distributed in a triangle, the spacing distances of the three fluorescent microspheres are different, and the spacing distances are all in the order of millimeters, wherein the fluorescent microsphere corresponding to the intersection of the longest spacing distance segment and the second longest spacing distance segment is recorded as the first fluorescent microsphere, the fluorescent microsphere corresponding to the intersection of the longest spacing distance segment and the shortest spacing distance segment is recorded as the second fluorescent microsphere, and the fluorescent microsphere corresponding to the intersection of the second longest spacing distance segment and the shortest spacing distance segment is recorded as the third fluorescent microsphere; the substrate is fixed in parallel on a six-dimensional calibration displacement stage, the six-dimensional calibration displacement stage with the substrate is placed under a fluorescence microscope, after turning on the fluorescent excitation light source, it is irradiated on the three fluorescent microspheres, so that the three fluorescent microspheres emit fluorescence, and the three fluorescent microspheres are imaged on the charge-coupled image sensor.

[0016] Optionally, the method of obtaining a respective XY-axis width ratio based on the imaging of each fluorescent microsphere and determining a longitudinal object plane and a normal vector of the longitudinal object plane of the fluorescence microscope includes: fitting the images of the three fluorescent microspheres through a two-dimensional Gaussian function to obtain the imaging center positions of the three fluorescent microspheres and the width values of the respective light spot imaging intensity distributions along the X-axis and Y-axis directions of the imaging surface of the charge-coupled image sensor, and obtaining respective XY-axis width ratios; causing the six-dimensional calibration stage to perform two non-parallel translational motions in two motion directions, selecting a fluorescent microsphere, and obtaining three XY-axis width ratios corresponding to three images of the fluorescent microsphere before and after the movement on the charge-coupled image sensor; if the three XY-axis width ratios are the same, it means that the plane determined by the two translational motion directions is a longitudinal object plane of the fluorescence microscope; traversing the pitch and yaw postures of the six-dimensional calibration stage with a minimum step size, performing the above-mentioned translation motion in each posture case, obtaining the three XY-axis width ratios corresponding to the selected fluorescent microsphere, and finding the posture vector ( m , n , q ) is used as the vector value in the six-dimensional calibration stage's own motion coordinate system, which is the normal vector of a determined longitudinal object plane.

[0017] Optionally, the method of obtaining the microscopic magnification function of each fluorescent microsphere according to the functional relationship between the longitudinal object plane height function and the XY axis width ratio of each fluorescent microsphere includes: moving the six-dimensional calibration stage along the posture vector ( m , n , q) direction, and the first fluorescent microsphere, the second fluorescent microsphere and the third fluorescent microsphere are all imaged, and the functional relationship between the different longitudinal object plane heights of each fluorescent microsphere in the longitudinal object plane relative to the focus and the ratio of the XY axis width of the fluorescent microsphere imaging is obtained, and the longitudinal object plane height function of each fluorescent microsphere is obtained; on each longitudinal object plane, the six-dimensional calibration stage is translated by a displacement value, and the displacement measurement value of each fluorescent microsphere is obtained on the charge-coupled image sensor, and the microscope magnification value on each longitudinal object plane is obtained by dividing the displacement measurement value of each fluorescent microsphere by the displacement value of the six-dimensional calibration stage.

[0018] Optionally, starting the calibrated turntable to ensure that each fluorescent microsphere can be imaged on the charge-coupled image sensor during one rotation of the turntable shaft includes: fixing the fluorescence microscope on a six-dimensional adjustment displacement stage, fixing the substrate with three fluorescent microspheres on a micro-adjustment stage, and fixing the micro-adjustment stage on the turntable shaft of the calibrated turntable; starting the calibrated turntable to rotate the turntable shaft one circle to ensure that the three fluorescent microspheres can be imaged by the fluorescence microscope during one rotation of the turntable shaft; if any fluorescent microspheres are not imaged, adjusting the micro-adjustment stage until all fluorescent microspheres can be imaged.

[0019] Optionally, the spatial plane coordinate value of each fluorescent microsphere mapped to the imaging plane coordinate of the charge-coupled image sensor is obtained according to the microscopic magnification function and imaging centroid coordinates of each fluorescent microsphere, and a plane ellipse function is fitted to determine that the rotation axis of the turntable is parallel to the imaging optical axis of the fluorescence microscope, including: after determining that all fluorescent microspheres can be imaged, starting the calibrated turntable again, rotating the turntable axis of the calibrated turntable by a minimum step angle and then stopping, recording the imaging of each fluorescent microsphere by the fluorescence microscope, fitting the imaging light intensity by a two-dimensional Gaussian function to obtain the imaging centroid coordinates and imaging XY axis width ratio of each fluorescent microsphere in the imaging plane coordinate of the charge-coupled image sensor, finding the microscopic magnification function value corresponding to the longitudinal object plane height of each fluorescent microsphere through the imaging XY axis width ratio of each fluorescent microsphere, dividing the imaging centroid coordinate by the microscopic magnification function value, and obtaining the mapping of each fluorescent microsphere to the charge-coupled image sensor. The spatial plane coordinate value under the imaging plane coordinate of the image sensor; select a fluorescent microsphere, and after the turntable axis rotates one circle, obtain a series of different spatial plane coordinate values of the selected fluorescent microsphere, and use a general elliptical function whose major and minor axes of the ellipse are not parallel to the coordinate axis to fit the plane elliptical function. The fitted ellipse is the plane mapping space trajectory drawn by the fluorescent microsphere when the turntable axis rotates, and the length value of the major and minor axes of the fitted ellipse at this time is recorded. The pitch and yaw postures of the six-dimensional adjustment displacement stage are traversed with the minimum step size. The turntable is rotated for a complete rotation cycle in each posture, so that a length value of the major and minor axes of the fitted ellipse can be obtained in each posture. When the major axis and minor axis of the fitted ellipse corresponding to a posture are the minimum values of all traversed postures, that is, when the rotation axis is perpendicular to the imaging surface of the charge-coupled image sensor, the length of the mapped imaging space plane trajectory is the shortest, and at this time the turntable rotation axis is parallel to the imaging optical axis of the fluorescence microscope.

[0020] Optionally, at the starting moment of the turntable axis, the spatial three-dimensional coordinate value of each fluorescent microsphere is obtained according to the spatial plane coordinate value of each fluorescent microsphere and the longitudinal object plane height function value of each fluorescent microsphere, and the angle between the substrate plane and the X-axis of the spatial coordinate system of the fluorescent microsphere and the angle between the substrate plane and the Y-axis of the spatial coordinate system of the fluorescent microsphere are obtained, including: after determining that the rotation axis is parallel to the imaging optical axis of the fluorescence microscope, starting the calibrated turntable again to rotate the turntable axis one circle, and stopping after each rotation of a minimum step angle, and recording the imaging data of the fluorescence microscope; the angular position of the turntable axis at the starting moment is recorded as the starting position, and the spatial three-dimensional coordinate value of each fluorescent microsphere is obtained by adding the spatial plane coordinate values on the imaging surface of the three charge-coupled image sensors and the longitudinal object plane height function values of the three fluorescent microspheres. The spatial distance of the three fluorescent microspheres is obtained by the spatial three-dimensional coordinate values of the three fluorescent microspheres, thereby determining the first fluorescent microsphere, the second fluorescent microsphere and the third fluorescent microsphere; the spatial three-dimensional coordinates of the three fluorescent microspheres are recorded as ( xA启 , y A启 , z A启 )、( x B启 , y B启 , z B启 )and( x C启 , y C启 , z C启 ); From the spatial three-dimensional coordinates of the three fluorescent microspheres, the spatial coordinates of the foot of the perpendicular from the third fluorescent microsphere to the spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere are obtained. The spatial coordinates of the foot of the perpendicular are recorded as ( x N启 , y N启 , z N启 ), which is expressed as follows:

[0021] ;

[0022] The spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere α AB启 , and the third fluorescent microsphere with the vertical foot ( x N启 , y N启 , z N启 ) determines the spatial straight line α CN启 , the angles between the Y axis and the Y axis of the YZ axis plane of the fluorescent microsphere space coordinate system are expressed as:

[0023]

[0024] ;

[0025] The spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere β AB启 , and the third fluorescent microsphere with the vertical foot ( x N启 , y N启 , z N启 ) determines the spatial straight line β CN启 , the angles between the X and Z axis planes of the fluorescent microsphere spatial coordinate system and its X axis are expressed as:

[0026]

[0027] .

[0028] Optionally, in the fluorescent microsphere space coordinate system, when the turntable axis is at the starting position, the angle between the substrate plane with three fluorescent microspheres and the X-axis represents the initial deflection angle The angle between the substrate plane with three fluorescent microspheres and the Y axis represents the initial pitch angle. .

[0029] Optionally, obtaining calibration data of the accuracy of the turntable encoder within a complete rotation cycle based on the fitted ellipse and the angle value of each turntable shaft rotation step angle encoder includes: the turntable shaft rotates one circle at a minimum step angle, and a series of three-dimensional spatial coordinates of each fluorescent microsphere in the fluorescent microsphere space coordinate system at each turntable shaft rotation step angle is recorded, and the series of three-dimensional spatial coordinates of each fluorescent microsphere are uniformly marked as ( x A , y A , z A )、( x B , y B , z B )and( x C , y C , z C ); A series of XY axis plane coordinates of the three fluorescent microspheres ( x A , y A )、( x B , y B )and( x C , y C ) were fitted with a plane ellipse function, and the fitting ellipse with the largest major axis and its corresponding fluorescent microsphere were selected. The central plane coordinates of the fitting ellipse were obtained as ( x o , y o ), and any coordinate point on the selected fitting ellipse function to the ellipse center ( x o , y o ) and the major axis of the ellipse i , the angle at the starting position is i 启 ;Record the encoder angle value when each turntable shaft rotates the step angle d , the angle value of the encoder at the starting position is d 启 , ( i - i 启 )and( d - d 启 ) represents the calibration data of the turntable encoder accuracy within a complete rotation cycle;

[0030] The radial runout data of the turntable shaft within a complete rotation cycle is obtained according to the spatial plane coordinate value of each fluorescent microsphere and the center of the fitted ellipse, including: the XY axis plane coordinates of the selected fluorescent microsphere corresponding to each turntable shaft rotation step angle to ( x o , y o ) distance, the distance from the coordinate point on the selected fitting ellipse function corresponding to this angle to the center of the ellipse ( x o , y o ) distance difference, which represents the radial runout data of the turntable shaft within a complete rotation cycle;

[0031] The axial runout data of the turntable shaft within a complete rotation cycle is obtained according to the spatial three-dimensional coordinate value of each fluorescent microsphere, including: z A - z A启 or z B - z B启 or z C - z C启 Indicates that each turntable shaft rotation step angle corresponds to all axial runout data within a complete rotation cycle;

[0032] The calibration data of the yaw and pitch vibration angles within a complete rotation cycle are obtained based on the angle between the substrate plane and the X-axis and the angle between the substrate plane and the Y-axis, including: the yaw angle corresponding to the rotation step angle of each turntable axis and pitch angle , and Represent the calibration data of the yaw and pitch vibration angles within a complete rotation cycle, respectively, where α AB Indicates the spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere corresponding to each turntable axis rotation step angle,α CN Indicates the angle between the third fluorescent microsphere and the vertical foot corresponding to each step angle of the turntable axis rotation ( x N , y N , z N ) determines the space straight line, β AB Indicates the spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere corresponding to each turntable axis rotation step angle, β CN Indicates the angle between the third fluorescent microsphere and the vertical foot corresponding to each step angle of the turntable axis rotation ( x N , y N , z N ) is a straight line in space determined by .

[0033] This application implements a method that can achieve simultaneous calibration of the accuracy of any angle point within the full cycle of the turntable encoder, shaft diameter runout, and yaw and pitch vibration angles, without adding additional instruments or devices, thereby achieving full-cycle calibration of the accuracy of the encoder assembled on a high-precision turntable and the attitude of the rotating shaft, laying the necessary technical foundation for improving the accuracy and stability of the turntable, and is easy to operate.

[0034] In order to make the above features and advantages of the application more obvious and easy to understand, the following embodiments are given and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the three-dimensional measurement calibration device for the turntable shaft and its encoder.

[0036] Figure 2 FIG. 1 is a schematic diagram showing a substrate 10 fixed with three fluorescent microspheres fixed on a six-dimensional precision calibration stage 11 .

[0037] Figure 3 Schematic diagram of using a fluorescence microscope to calibrate the calibrated turntable shaft and its encoder.

[0038] Figure 4 This is a flow chart of a method for calibrating a turntable shaft and its encoder provided in this application.

[0039] In the figure: 1 objective lens, 2 cylindrical lens, 3 charge-coupled image sensor, 4 imaging optical axis, 5 fluorescence excitation light source, 6 fluorescence microscope, 7 fluorescent microspheres, 8 fluorescent microspheres, 9 fluorescent microspheres, 10 substrate, 11 six-dimensional precision calibration displacement stage, 12 focal longitudinal object plane, 13 calibrated turntable, 14 turntable axis, 15 rotation axis, 16 six-dimensional precision adjustment displacement stage, 17 micro adjustment stage.

[0040] In the drawings, like reference numerals refer to the same drawing elements. DETAILED DESCRIPTION

[0041] To make the purpose and technical solutions of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] The specific embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0043] The present application provides a method for calibrating a turntable shaft and an encoder thereof, which is used to detect and calibrate the turntable shaft and the encoder to be calibrated.

[0044] See also Figure 1 , Figure 1 This is a schematic diagram of a three-dimensional measurement calibration device for a turntable shaft and its encoder. A cylindrical lens 2 is placed between an objective lens 1 and a charge-coupled image sensor (CCD) 3. The bottom surface of the cylindrical lens 2 is parallel to the CCD 3. The edge where the semicircular cross-section of the cylindrical lens 2 intersects with the bottom surface of the cylindrical lens 2 is parallel to the X-axis direction of the imaging surface of the CCD 3. The normal vector of the CCD 3 is parallel to the imaging optical axis of the objective lens 1. An annular fluorescent excitation light source 5 is arranged on the outside of the objective lens 1. The objective lens 1, the CCD 3, the cylindrical lens 2, and the fluorescent excitation light source 5 constitute a spatially fixed fluorescent microscope 6 with astigmatic imaging capability. Three submillimeter fluorescent microspheres are fixed on a planar substrate 10. The three fluorescent microspheres are distributed in a triangle and are spaced at different distances, all on the order of millimeters.

[0045] As an example, among the three fluorescent microspheres, the fluorescent microsphere corresponding to the intersection of the longest interval distance segment and the second longest interval distance segment is recorded as fluorescent microsphere 7, the fluorescent microsphere corresponding to the intersection of the longest interval distance segment and the shortest interval distance segment is recorded as fluorescent microsphere 8, and the fluorescent microsphere corresponding to the intersection of the second longest interval distance segment and the shortest interval distance segment is recorded as fluorescent microsphere 9.

[0046] As an example, the substrate 10 can be fixed on a six-dimensional calibration platform, which includes a six-dimensional precision calibration platform 11; Figure 2 , Figure 2 FIG. 1 is a schematic diagram showing a substrate 10 fixed with three fluorescent microspheres fixed on a six-dimensional precision calibration stage 11 .

[0047] Please continue reading Figure 3 , Figure 3 Schematic diagram of using a fluorescence microscope to calibrate the calibrated turntable shaft and its encoder.

[0048] As an example, the substrate 10 may also be fixed on a micro-adjustment stage 17 , and the micro-adjustment stage 17 is fixed on the turntable shaft 14 of the calibrated turntable 13 .

[0049] As an example, see Figure 4 , Figure 4 This is a flow chart of a method for calibrating a turntable shaft and its encoder provided by the present application. The method for calibrating a turntable shaft and its encoder provided by the present application includes steps S1 to S8:

[0050] Step S1: an objective lens 1, a charge coupled image sensor 3, a cylindrical lens 2 and a fluorescence excitation light source 5 are used to form a fluorescence microscope 6 with an astigmatic imaging function and a fixed spatial position.

[0051] Step S2: Three sub-millimeter fluorescent microspheres are fixed on a planar substrate 10 so that the three fluorescent microspheres are imaged on a charge coupled image sensor.

[0052] Step S3: Obtain respective XY axis width ratios according to the imaging of each fluorescent microsphere, and determine a longitudinal object plane and a normal vector of the longitudinal object plane of the fluorescence microscope 6 .

[0053] Step S4: Obtaining the microscopic magnification function of each fluorescent microsphere according to the functional relationship between the longitudinal object plane height function and the XY axis width ratio of each fluorescent microsphere.

[0054] Step S5: Start the calibrated turntable 13 to ensure that each fluorescent microsphere can be imaged on the charge coupled image sensor during one rotation of the turntable shaft 14.

[0055] Step S6: According to the microscopic magnification function and imaging centroid coordinates of each fluorescent microsphere, the spatial plane coordinate value of each fluorescent microsphere mapped to the imaging plane coordinate of the charge coupled image sensor 3 is obtained, and a plane ellipse function fitting is performed to determine that the rotation axis of the calibrated turntable 13 is parallel to the imaging optical axis 4 of the fluorescence microscope 6.

[0056] Step S7: At the start moment of the turntable rotation axis 14, the spatial three-dimensional coordinate value of each fluorescent microsphere is obtained according to the spatial plane coordinate value of each fluorescent microsphere and the respective longitudinal object plane height function value, and the angle between the plane of the substrate 10 and the X-axis of the spatial coordinate system of the fluorescent microsphere and the angle between the plane of the substrate 10 and the Y-axis of the spatial coordinate system of the fluorescent microsphere are obtained.

[0057] Step S8: When the turntable shaft 14 rotates, calibration data of the turntable encoder accuracy within a complete rotation cycle is obtained based on the fitted ellipse and the angle value of each turntable shaft 14 rotation step angle encoder; radial runout data within a complete rotation cycle of the turntable shaft 14 is obtained based on the spatial plane coordinate value of each fluorescent microsphere and the center of the fitted ellipse; axial runout data within a complete rotation cycle of the turntable shaft 14 is obtained based on the spatial three-dimensional coordinate value of each fluorescent microsphere; calibration data of the yaw and pitch vibration angles within a complete rotation cycle are obtained based on the angle between the plane of the substrate 10 and the X-axis and the angle between the plane of the substrate 10 and the Y-axis.

[0058] As an example, step S1 specifically includes: placing a cylindrical lens 2 between the objective lens 1 and the charge-coupled image sensor 3, the bottom surface of the cylindrical lens 2 is parallel to the charge-coupled image sensor 3, and the edge where the semicircular cross-section of the cylindrical lens 2 intersects with the bottom surface of the cylindrical lens 2 is parallel to the X-axis direction of the imaging surface of the charge-coupled image sensor 3, the normal vector of the charge-coupled image sensor 3 is parallel to the imaging optical axis 4 of the objective lens 1, and the outer side of the objective lens 1 is provided with an annular fluorescence excitation light source 5. When the fluorescence excitation light source 5 is turned on, the excitation light beam can be incident on the spatial region under the objective lens 1. The objective lens 1, the charge-coupled image sensor 3, the cylindrical lens 2 and the fluorescence excitation light source 5 constitute a fluorescence microscope 6 with an astigmatic imaging function that is fixed in spatial position.

[0059] As an example, step S2 specifically includes: fixing three submillimeter fluorescent microspheres on a planar substrate 10, and the three fluorescent microspheres are distributed in a triangle, and the spacing distances between the three fluorescent microspheres are different, and the spacing distances are all in the order of millimeters, wherein the fluorescent microsphere corresponding to the intersection of the longest spacing distance segment and the second longest spacing distance segment is recorded as fluorescent microsphere 7, the fluorescent microsphere corresponding to the intersection of the longest spacing distance segment and the shortest spacing distance segment is recorded as fluorescent microsphere 8, and the fluorescent microsphere corresponding to the intersection of the second longest spacing distance segment and the shortest spacing distance segment is recorded as fluorescent microsphere 9. Then, the substrate 10 is fixed in parallel on a six-dimensional precision calibration displacement stage 11. The six-dimensional precision calibration displacement stage 11 with the substrate 10 is placed under a fluorescence microscope 6, and after turning on the fluorescence excitation light source 5, it is irradiated on the three fluorescent microspheres, causing them to emit fluorescence, so that the three fluorescent microspheres can be imaged on the charge-coupled image sensor 3.

[0060] As an example, step S3 specifically includes: imaging the three fluorescent microspheres using two-dimensional Gaussian function fitting. This not only obtains the centroid positions of the three fluorescent microspheres, but also the widths of their respective spot imaging intensity distributions along the X- and Y-axis directions of the imaging plane of the charge-coupled image sensor 3, thereby obtaining their respective XY-axis width ratios, i.e., the ratios of the widths in the X- and Y-axis directions. On different longitudinal object planes, i.e., those perpendicular to the imaging optical axis 4, the X- and Y-axis width ratios are different due to the astigmatism of the cylindrical lens 2. The six-dimensional precision calibration stage 11 is then subjected to two non-parallel translational motions. A fluorescent microsphere is selected, and three XY-axis width ratios corresponding to the three images of the fluorescent microsphere before and after its movement on the charge-coupled image sensor 3 are obtained. If these three XY-axis width ratios are the same, it indicates that the plane defined by the two translational motion directions is a longitudinal object plane of the fluorescence microscope 6. Traverse the pitch and yaw postures of the six-dimensional precision calibration stage 11 with the minimum step size, perform the above-mentioned translation motion in each posture, and obtain the three XY axis width ratios corresponding to the selected fluorescent microspheres, and find the posture vector of the six-dimensional precision calibration stage 11 when the three XY axis width ratios are the same ( m , n , q ) is used as the vector value in the six-dimensional precision calibration translation stage 11's own motion coordinate system. This vector value is the normal vector of a determined longitudinal object plane and is also the imaging optical axis 4 vector.

[0061] As an example, step S4 specifically includes: moving the six-dimensional precision calibration platform 11 along the posture vector ( m , n , q ) direction, and make the fluorescent microspheres 7, 8 and 9 have images, the functional relationship between the different longitudinal object plane heights of each fluorescent microsphere at the longitudinal object plane 12 relative to the focus and the ratio of the XY axis width of the fluorescent microsphere imaging can be obtained. The three longitudinal object plane height functions are respectively f A ( w A ), f B ( w B )and f C ( w C ),in, w A 、 w B and w Care the XY-axis width ratios of fluorescent microspheres 7, 8, and 9, respectively. Furthermore, the six-dimensional precision calibration stage 11 is translated by a displacement value on each longitudinal object plane, and a displacement measurement value of each fluorescent microsphere is obtained on the charge-coupled image sensor 3. The displacement measurement value of each fluorescent microsphere is divided by the displacement value of the six-dimensional precision calibration stage 11 to obtain the microscopic magnification value on each longitudinal object plane. The microscopic magnification value varies with the height of the longitudinal object plane. The microscopic magnification value is a function value related to the longitudinal object plane height or the XY-axis width ratio of the fluorescent microsphere imaging. The microscopic magnification functions of the three fluorescent microspheres are respectively recorded as N A ( w A ), N B ( w B )and N C ( w C ).

[0062] As an example, step S5 specifically includes: securing the fluorescence microscope 6 to a six-dimensional adjustable translation stage, which includes a six-dimensional precision adjustable translation stage 16; then securing the substrate 10 with the three fluorescent microspheres to a micro-adjustable stage 17, which is then secured to the turntable shaft 14 of the calibrated turntable 13. The calibrated turntable 13 is activated to rotate the turntable shaft 14 one revolution, ensuring that all three fluorescent microspheres are imaged by the fluorescence microscope 6 during the rotation of the turntable shaft 14. If any fluorescent microspheres are not imaged, the micro-adjustable stage 17 is adjusted until all fluorescent microspheres are imaged.

[0063] As an example, step S6 specifically includes: after determining that all fluorescent microspheres can be imaged, starting the calibrated turntable 13 again, rotating the turntable shaft 14 of the calibrated turntable 13 by a minimum step angle and then stopping, and then recording the imaging of each fluorescent microsphere by the fluorescence microscope 6, and fitting the imaging light intensity by a two-dimensional Gaussian function to obtain the imaging center coordinates and imaging XY axis width ratio of each fluorescent microsphere in the imaging plane coordinates of the charge-coupled image sensor 3. The imaging XY axis width ratio of each fluorescent microsphere can be used to find the microscopic magnification function value corresponding to the longitudinal object plane height of each fluorescent microsphere, and the imaging center coordinates are divided by the microscopic magnification function value to obtain the spatial plane coordinate value of each fluorescent microsphere mapped to the imaging plane coordinates of the charge-coupled image sensor 3. A fluorescent microsphere is selected, and after the turntable shaft 14 rotates one circle, a series of different spatial plane coordinate values of the selected fluorescent microsphere can be obtained. These data are fitted with a plane ellipse function using a general ellipse function in which the major and minor axes of the ellipse are not parallel to the coordinate axis. The fitted ellipse is the plane mapping space trajectory drawn by the fluorescent microsphere when the turntable shaft 14 rotates. The length values of the major and minor axes of the fitted ellipse at this time are recorded, and the pitch and yaw postures of the six-dimensional precision adjustment translation stage 16 are traversed with a minimum step size. The turntable is rotated for a complete rotation cycle in each posture, so that a length value of the major and minor axes of the fitted ellipse can be obtained in each posture. When the major axis and minor axis of the fitted ellipse corresponding to a posture are both the minimum values of all traversed postures, that is, when the rotation axis 15 is perpendicular to the imaging surface of the charge-coupled image sensor 3, the length of the mapped image space plane trajectory is the shortest. At this time, the turntable rotation axis 15 is parallel to the imaging optical axis 4 of the fluorescence microscope 6;

[0064] As an example, step S7 specifically includes: after determining that the rotation axis 15 is parallel to the imaging optical axis 4 of the fluorescence microscope 6, the calibrated turntable 13 is restarted to rotate the turntable shaft 14 one circle. After each minimum step angle rotation, the turntable shaft 14 stops and the imaging data of the fluorescence microscope 6 is recorded. The angular position of the turntable shaft 14 at the startup moment is recorded as the starting position. Since the spatial coordinate system in which the three fluorescent microspheres are located is a coordinate system obtained by translating the spatial coordinate system determined by the charge-coupled image sensor 3 along the imaging optical axis 4 to the focal longitudinal object plane 12, that is, the spatial plane coordinate values on the imaging plane of the charge-coupled image sensor 3 are equal to the spatial plane coordinate values on the XY axis plane of the spatial coordinate system of the fluorescent microspheres, the three spatial plane coordinate values of each fluorescent microsphere are obtained by adding the longitudinal object plane height function values of the three fluorescent microspheres to the obtained three spatial plane coordinate values on the imaging plane of the charge-coupled image sensor 3. The spatial distance between the three fluorescent microspheres can be obtained through the three spatial three-dimensional coordinate values of the fluorescent microspheres, thereby determining the fluorescent microspheres 7, 8, and 9. At this time, the spatial three-dimensional coordinates of the three fluorescent microspheres are recorded as ( x A启 ,y A启 , z A启 )、( x B启 , y B启 , z B启 )and( x C启 , y C启 , z C启 ), in addition, the spatial coordinates of the foot of the perpendicular from the fluorescent microsphere 9 to the straight line in space determined by the fluorescent microspheres 7 and 8 can be obtained from the spatial three-dimensional coordinates of these three fluorescent microspheres. The coordinates of the foot of the perpendicular are recorded as ( x N启 , y N启 , z N启 ), which is expressed as follows:

[0065]

[0066] Specifically, the space straight line determined by the fluorescent microspheres 7 and 8 α AB启 , and fluorescent microspheres 9 with vertical feet ( x N启 , y N启 , z N启 ) determines the spatial straight line α CN启 , the angles between the Y axis and the Y axis of the YZ axis plane of the fluorescent microsphere space coordinate system are expressed as:

[0067]

[0068]

[0069] Specifically, the space straight line determined by the fluorescent microspheres 7 and 8 β AB启 , and fluorescent microspheres 9 with vertical feet ( x N启 , y N启 , z N启 ) determines the spatial straight line β CN启 , the angles between the X and Z axis planes of the fluorescent microsphere spatial coordinate system and its X axis are expressed as:

[0070]

[0071]

[0072] From this, we can get the angle between the plane of the substrate 10 with three fluorescent microspheres and the X-axis when the turntable shaft 14 is at the starting position in the fluorescent microsphere space coordinate system, that is, the initial deflection angle is The angle between the substrate 10 plane with three fluorescent microspheres and the Y axis, that is, the initial pitch angle is .

[0073] As an example, step S8 specifically includes: rotating the turntable shaft 14 at a minimum step angle for one circle, recording a series of three-dimensional spatial coordinates of each fluorescent microsphere in the fluorescent microsphere spatial coordinate system at each turntable shaft rotation step angle, and uniformly marking the series of three-dimensional spatial coordinates of each fluorescent microsphere as ( x A , y A , z A )、( x B , y B , z B )and( x C , y C , z C ). Place three fluorescent microspheres in a series of XY axis plane coordinates ( x A , y A )、( x B , y B )and( x C , y C ) were fitted with a plane ellipse function, and the fitting ellipse with the largest major axis and its corresponding fluorescent microsphere were selected. The central plane coordinates of the fitting ellipse were obtained as ( x o , y o ), and any coordinate point on the selected fitting ellipse function to the ellipse center ( x o , y o ) and the major axis of the ellipse i , the angle at the starting position is i 启 . The angle value of the encoder when each turntable shaft 14 rotates the step angle is d , the angle value of the encoder at the starting position is d 启 , ( i - i 启 )and( d - d 启 ) is the calibration data of the turntable encoder accuracy within a complete rotation cycle. The XY axis plane coordinates of the selected fluorescent microsphere corresponding to each turntable shaft 14 rotation step angle are ( x o , y o ) distance, the distance from the coordinate point on the selected fitting ellipse function corresponding to this angle to the center of the ellipse ( x o , y o ) distance difference constitutes the radial runout data of the turntable shaft 14 within a complete rotation cycle. z A - z A启 or z B - z B启 or z C - z C启 That is, each turntable shaft 14 rotation step angle corresponds to all axial runout data within a complete rotation cycle. Similar to step S7, the deflection angle corresponding to each turntable shaft 14 rotation step angle can be obtained. and pitch angle , and is the calibration data of the yaw and pitch vibration angles within a complete rotation cycle, where α AB Indicates the spatial straight line determined by the fluorescent microspheres 7 and 8 corresponding to each step angle of rotation of the turntable shaft 14, α CN Indicates the angle between the fluorescent microsphere 9 and the vertical foot ( x N , y N , z N ) determines the space straight line, β AB Indicates the spatial straight line determined by the fluorescent microspheres 7 and 8 corresponding to each step angle of rotation of the turntable shaft 14, β CNIndicates the angle between the fluorescent microsphere 9 and the vertical foot ( x N , y N , z N ) is a straight line in space determined by .

[0074] This application implements a method that can achieve simultaneous calibration of the accuracy of any angle point within the full cycle of the turntable encoder, shaft diameter runout, and yaw and pitch vibration angles, without adding additional instruments or devices, thereby achieving full-cycle calibration of the accuracy of the encoder assembled on a high-precision turntable and the attitude of the rotating shaft, laying the necessary technical foundation for improving the accuracy and stability of the turntable, and is easy to operate.

[0075] Although the present application has been disclosed above with reference to the embodiments, they are not intended to limit the present application. Anyone with ordinary knowledge in the technical field may make slight changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be determined by the scope of the appended patent application.

Claims

1. A method for calibrating a turntable shaft and its encoder, characterized in that: include, An objective lens, a charge coupled image sensor, a cylindrical lens and a fluorescence excitation light source are used to form a fluorescence microscope with astigmatism imaging function and a fixed spatial position. Three fluorescent microspheres are fixed on a flat substrate so that the three fluorescent microspheres are imaged on a charge-coupled image sensor; Based on the imaging of each fluorescent microsphere, the respective XY axis width ratio is obtained to determine a longitudinal object plane and a normal vector of the longitudinal object plane of the fluorescence microscope; The microscopic magnification function of each fluorescent microsphere is obtained according to the functional relationship between the longitudinal object plane height function and the XY axis width ratio of each fluorescent microsphere; Start the calibrated turntable to ensure that each fluorescent microsphere can be imaged on the charge-coupled image sensor during one rotation of the turntable axis; The spatial plane coordinate value of each fluorescent microsphere mapped to the imaging plane coordinate of the charge coupled image sensor is obtained according to the microscopic magnification function and the imaging centroid coordinate of each fluorescent microsphere, and a plane ellipse function fitting is performed to determine that the rotation axis of the turntable is parallel to the imaging optical axis of the fluorescence microscope; At the start moment of the turntable axis rotation, the spatial three-dimensional coordinate value of each fluorescent microsphere is obtained according to the spatial plane coordinate value of each fluorescent microsphere and the longitudinal object plane height function value, and the angle between the substrate plane and the X axis of the spatial coordinate system of the fluorescent microsphere and the angle between the substrate plane and the Y axis of the spatial coordinate system of the fluorescent microsphere are obtained; When the turntable shaft rotates, the calibration data of the turntable encoder accuracy within a complete rotation cycle is obtained based on the fitted ellipse and the angle value of each turntable shaft rotation step angle encoder; the radial runout data within a complete rotation cycle of the turntable shaft is obtained based on the spatial plane coordinate value of each fluorescent microsphere and the center of the fitted ellipse; and the axial runout data within a complete rotation cycle of the turntable shaft is obtained based on the spatial three-dimensional coordinate value of each fluorescent microsphere. The calibration data of the yaw and pitch vibration angles within a complete rotation cycle are obtained based on the angles between the substrate plane and the X-axis and the angles between the substrate plane and the Y-axis.

2. The method for calibrating a turntable shaft and its encoder according to claim 1, wherein: The invention discloses a fluorescence microscope with an astigmatic imaging function that is fixed in spatial position and is constructed by using an objective lens, a charge coupled image sensor, a cylindrical lens, and a fluorescence excitation light source. The invention comprises the following steps: placing the cylindrical lens between the objective lens and the charge coupled image sensor, wherein the bottom surface of the cylindrical lens is parallel to the charge coupled image sensor, and the edge where the semicircular cross section of the cylindrical lens intersects with the bottom surface of the cylindrical lens is parallel to the X-axis direction of the imaging surface of the charge coupled image sensor; the normal vector of the charge coupled image sensor is parallel to the imaging optical axis of the objective lens; a fluorescence excitation light source is sheathed on the outer side of the objective lens; when the fluorescence excitation light source is turned on, the excitation light beam is incident on the spatial area under the objective lens; and the objective lens, the charge coupled image sensor, the cylindrical lens, and the fluorescence excitation light source constitute the fluorescence microscope with an astigmatic imaging function that is fixed in spatial position.

3. The method for calibrating a turntable shaft and its encoder according to claim 2, wherein: The three fluorescent microspheres are fixed on a planar substrate, and the three fluorescent microspheres are imaged on a charge-coupled image sensor, including: fixing the three fluorescent microspheres on a planar substrate, the three fluorescent microspheres are distributed in a triangle, the spacing distances between the three fluorescent microspheres are different, and the spacing distances are all on the order of millimeters, wherein the fluorescent microsphere corresponding to the intersection of the longest spacing distance segment and the second longest spacing distance segment is recorded as the first fluorescent microsphere, the fluorescent microsphere corresponding to the intersection of the longest spacing distance segment and the shortest spacing distance segment is recorded as the second fluorescent microsphere, and the fluorescent microsphere corresponding to the intersection of the second longest spacing distance segment and the shortest spacing distance segment is recorded as the third fluorescent microsphere; the substrate is fixed in parallel on a six-dimensional calibration displacement stage, the six-dimensional calibration displacement stage with the substrate is placed under a fluorescence microscope, and after turning on a fluorescence excitation light source, it is irradiated on the three fluorescent microspheres, thereby causing the three fluorescent microspheres to emit fluorescence, and the three fluorescent microspheres are imaged on the charge-coupled image sensor.

4. The method for calibrating a turntable shaft and its encoder according to claim 3, wherein: The method obtains respective XY axis width ratios based on the imaging of each fluorescent microsphere, and determines a longitudinal object plane and a normal vector of the longitudinal object plane of the fluorescence microscope, including: fitting the images of the three fluorescent microspheres through two-dimensional Gaussian functions respectively, obtaining the imaging center positions of the three fluorescent microspheres and the width values of the respective light spot imaging light intensity distributions along the X-axis and Y-axis directions of the imaging surface of the charge-coupled image sensor, and obtaining respective XY axis width ratios; causing the six-dimensional calibration displacement stage to perform two non-parallel translational motions in two motion directions, selecting a fluorescent microsphere, and obtaining three XY axis width ratios corresponding to three images of the fluorescent microsphere before and after the movement on the charge-coupled image sensor. If the three XY axis width ratios are the same, it means that the plane determined by the two translational motion directions is a longitudinal object plane of the fluorescence microscope; traversing the pitch and yaw postures of the six-dimensional calibration displacement stage with a minimum step size, performing the above-mentioned translation motion in each posture case, obtaining the three XY axis width ratios corresponding to the selected fluorescent microsphere, and finding the posture vector ( m , n , q ) is used as the vector value in the six-dimensional calibration stage's own motion coordinate system, which is the normal vector of a determined longitudinal object plane.

5. The method for calibrating a turntable shaft and its encoder according to claim 4, wherein: The method of obtaining the microscopic magnification function of each fluorescent microsphere according to the functional relationship between the longitudinal object plane height function and the XY axis width ratio of each fluorescent microsphere comprises: moving the six-dimensional calibration stage along the posture vector ( m , n , q ) direction, and the first fluorescent microsphere, the second fluorescent microsphere and the third fluorescent microsphere are all imaged, and the functional relationship between the different longitudinal object plane heights of each fluorescent microsphere in the longitudinal object plane relative to the focus and the ratio of the XY axis width of the fluorescent microsphere imaging is obtained, and the longitudinal object plane height function of each fluorescent microsphere is obtained; on each longitudinal object plane, the six-dimensional calibration stage is translated by a displacement value, and the displacement measurement value of each fluorescent microsphere is obtained on the charge-coupled image sensor, and the microscope magnification value on each longitudinal object plane is obtained by dividing the displacement measurement value of each fluorescent microsphere by the displacement value of the six-dimensional calibration stage.

6. The method for calibrating a turntable shaft and its encoder according to claim 5, wherein: The method of starting the calibrated turntable to ensure that each fluorescent microsphere can be imaged on the charge-coupled image sensor during one rotation of the turntable shaft includes: fixing the fluorescence microscope on a six-dimensional adjustment displacement stage, fixing the substrate with three fluorescent microspheres on a micro-adjustment stage, and fixing the micro-adjustment stage on the turntable shaft of the calibrated turntable; starting the calibrated turntable to rotate the turntable shaft one circle, ensuring that the three fluorescent microspheres can be imaged by the fluorescence microscope during one rotation of the turntable shaft; if any fluorescent microspheres are not imaged, adjusting the micro-adjustment stage until all fluorescent microspheres are imaged.

7. The method for calibrating a turntable shaft and its encoder according to claim 6, wherein: The method includes: after determining that all fluorescent microspheres can be imaged, restarting the calibrated turntable, rotating the turntable axis of the calibrated turntable by a minimum step angle and then stopping, recording the imaging of each fluorescent microsphere by the fluorescence microscope, fitting the imaging light intensity by a two-dimensional Gaussian function to obtain the imaging center coordinates and imaging XY axis width ratio of each fluorescent microsphere in the imaging plane coordinates of the charge coupled image sensor, finding the microscopic magnification function value corresponding to the longitudinal object plane height of each fluorescent microsphere through the imaging XY axis width ratio of each fluorescent microsphere, dividing the imaging center coordinates by the microscopic magnification function value, and obtaining the image of each fluorescent microsphere mapped to the charge coupled image. The spatial plane coordinate value under the sensor imaging plane coordinate; select a fluorescent microsphere, and after the turntable axis rotates one circle, obtain a series of different spatial plane coordinate values of the selected fluorescent microsphere, and use a general elliptical function whose major and minor axes of the ellipse are not parallel to the coordinate axis to fit the plane elliptical function. The fitted ellipse is the plane mapping space trajectory drawn by the fluorescent microsphere when the turntable axis rotates, and the length value of the major and minor axes of the fitted ellipse at this time is recorded. The pitch and yaw postures of the six-dimensional adjustment displacement stage are traversed with the minimum step size. The turntable is rotated for a complete rotation cycle in each posture, so that a length value of the major and minor axes of the fitted ellipse can be obtained in each posture. When the major axis and minor axis of the fitted ellipse corresponding to a posture are the minimum values of all traversed postures, that is, when the rotation axis is perpendicular to the imaging surface of the charge-coupled image sensor, the length of the mapped imaging space plane trajectory is the shortest, and at this time the turntable rotation axis is parallel to the imaging optical axis of the fluorescence microscope.

8. The method for calibrating a turntable shaft and its encoder according to claim 7, wherein: At the starting moment of the turntable axis, the spatial three-dimensional coordinate value of each fluorescent microsphere is obtained according to the spatial plane coordinate value of each fluorescent microsphere and the longitudinal object plane height function value, and the angle between the substrate plane and the X-axis of the spatial coordinate system of the fluorescent microsphere and the angle between the substrate plane and the Y-axis of the spatial coordinate system of the fluorescent microsphere are obtained, including: after determining that the rotation axis is parallel to the imaging optical axis of the fluorescence microscope, starting the calibrated turntable again to rotate the turntable axis one circle, and stopping after each rotation of a minimum step angle, and recording the imaging data of the fluorescence microscope; the angular position of the turntable axis at the starting moment is recorded as the starting position, and the spatial three-dimensional coordinate value of each fluorescent microsphere is obtained by adding the spatial plane coordinate values on the imaging surface of the three charge-coupled image sensors and the longitudinal object plane height function values of the three fluorescent microspheres. The spatial distance of the three fluorescent microspheres is obtained by the spatial three-dimensional coordinate values of the three fluorescent microspheres, thereby determining the first fluorescent microsphere, the second fluorescent microsphere and the third fluorescent microsphere; the spatial three-dimensional coordinates of the three fluorescent microspheres are recorded as ( x A启 , y A启 , z A启 )、( x B启 , y B启 , z B启 )and( x C启 , y C启 , z C启 ); From the spatial three-dimensional coordinates of the three fluorescent microspheres, the spatial coordinates of the foot of the perpendicular from the third fluorescent microsphere to the spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere are obtained. The spatial coordinates of the foot of the perpendicular are recorded as ( x N启 , y N启 , z N启 ), which is expressed as follows: ； The spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere α AB启 , and the third fluorescent microsphere with the vertical foot ( x N启 , y N启 , z N启 ) determines the spatial straight line α CN启 , the angles between the Y axis and the Y axis of the YZ axis plane of the fluorescent microsphere space coordinate system are expressed as: ； The spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere β AB启 , and the third fluorescent microsphere with the vertical foot ( x N启 , y N启 , z N启 ) determines the spatial straight line β CN启 , the angles between the X and Z axis planes of the fluorescent microsphere spatial coordinate system and its X axis are expressed as: 。 9. The method for calibrating a turntable shaft and its encoder according to claim 8, wherein: In the fluorescent microsphere space coordinate system, when the turntable axis is at the starting position, the angle between the substrate plane with three fluorescent microspheres and the X-axis represents the initial deflection angle. ; The angle between the substrate plane with three fluorescent microspheres and the Y axis represents the initial pitch angle .

10. The method for calibrating a turntable shaft and its encoder according to claim 9, wherein: The calibration data of the turntable encoder accuracy within a complete rotation cycle is obtained based on the fitting ellipse and the angle value of each turntable shaft rotation step angle encoder, including: the turntable shaft rotates one circle at a minimum step angle, and a series of three-dimensional spatial coordinates of each fluorescent microsphere in the fluorescent microsphere space coordinate system at each turntable shaft rotation step angle are recorded, and the series of three-dimensional spatial coordinates of each fluorescent microsphere are uniformly marked as ( x A , y A , z A )、( x B , y B , z B )and( x C , y C , z C ); A series of XY axis plane coordinates of the three fluorescent microspheres ( x A , y A )、( x B , y B )and( x C , y C ) were fitted with a plane ellipse function, and the fitting ellipse with the largest major axis and its corresponding fluorescent microsphere were selected. The central plane coordinates of the fitting ellipse were obtained as ( x o , y o ), and any coordinate point on the selected fitting ellipse function to the ellipse center ( x o , y o ) and the major axis of the ellipse θ , the angle at the starting position is θ 启 ;Record the encoder angle value when each turntable shaft rotates the step angle δ , the angle value of the encoder at the starting position is δ 启 , ( θ - θ 启 )and( δ - δ 启 ) represents the calibration data of the turntable encoder accuracy within a complete rotation cycle; The radial runout data of the turntable shaft within a complete rotation cycle is obtained according to the spatial plane coordinate value of each fluorescent microsphere and the center of the fitted ellipse, including: the XY axis plane coordinates of the selected fluorescent microsphere corresponding to each turntable shaft rotation step angle to ( x o , y o ) distance, the distance from the coordinate point on the selected fitting ellipse function corresponding to this angle to the center of the ellipse ( x o , y o ) distance difference, which represents the radial runout data of the turntable shaft within a complete rotation cycle; The axial runout data of the turntable shaft within a complete rotation cycle is obtained according to the spatial three-dimensional coordinate value of each fluorescent microsphere, including: z A - z A启 or z B - z B启 or z C - z C启 Indicates that each turntable shaft rotation step angle corresponds to all axial runout data within a complete rotation cycle; The calibration data of the yaw and pitch vibration angles within a complete rotation cycle are obtained based on the angle between the substrate plane and the X-axis and the angle between the substrate plane and the Y-axis, including: the yaw angle corresponding to the rotation step angle of each turntable axis and pitch angle , and Represent the calibration data of the yaw and pitch vibration angles within a complete rotation cycle, respectively, where α AB Indicates the spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere corresponding to each turntable axis rotation step angle, α CN Indicates the angle between the third fluorescent microsphere and the vertical foot corresponding to each step angle of the turntable axis rotation ( x N , y N , z N ) determines the space straight line, β AB Indicates the spatial straight line determined by the first fluorescent microsphere and the second fluorescent microsphere corresponding to each turntable axis rotation step angle, β CN Indicates the angle between the third fluorescent microsphere and the vertical foot corresponding to each step angle of the turntable axis rotation ( x N , y N , z N ) is a straight line in space determined by .

Images