Rotary table rotating shaft and detection and calibration device for calibration of encoder of rotary table rotating shaft
By combining cylindrical lenses and fluorescence microscopes with fluorescent microspheres, the accuracy of turntable encoders at any angle point throughout their entire lifecycle and the calibration of the shaft attitude were solved, simplifying the operation process and improving the accuracy and stability of the turntable.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-10
- Publication Date
- 2026-04-14
AI Technical Summary
Existing turntable encoder calibration devices cannot achieve accurate calibration at any angle point throughout the entire cycle, and require additional instruments to measure shaft diameter runout and yaw pitch vibration, making operation inconvenient.
A combination of cylindrical lenses, fluorescence microscopes, and fluorescence microspheres is used to simultaneously calibrate the accuracy, shaft runout, and yaw and pitch vibration angles of the turntable encoder at any angle point throughout its entire cycle, through fluorescence microscope imaging and the coordination of a six-dimensional calibration displacement stage.
It enables accurate calibration at any angle point throughout the entire cycle of the turntable encoder, simplifies the operation process, eliminates the need for additional instruments, and improves the accuracy and stability of the turntable.
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Figure CN224121980U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of precision instruments, and in particular to a testing and calibration device for calibrating a turntable shaft and its encoder. Background Technology
[0002] High-precision turntables are not only a core technology carrier in the field of precision engineering, but their development will also directly boost the leapfrog development of key industries such as semiconductors, aerospace, and biomedicine, and provide basic support for scenarios such as smart factories and future laboratories, thus possessing profound value. The accuracy of the turntable's encoder resolution, as well as the accuracy of resolution due to shaft runout and vibration interference during rotation after assembly, constantly affect the turntable's rotational accuracy. Therefore, it is necessary to calibrate the turntable with the encoder already assembled. Currently, the commonly used calibration device for turntable encoders is the metrology technical specification: JJF1115-2004, which uses a calibration device combining a multi-faceted prism and an autocollimator. This device verifies the error of the circular grating encoding by measuring points at equal intervals, calibrating the encoder error within the interval angles to a single value. Therefore, this device is not a calibration verification of any angle point within the entire cycle of the circular grating in a strictly sense. Moreover, if it is also necessary to obtain the shaft diameter runout and yaw / pitch vibration angle, additional instrument transposition is required, so the operational efficiency is not very good. Utility Model Content
[0003] This application aims to provide a device that can simultaneously calibrate the accuracy of the turntable encoder at any angle point throughout the entire cycle, as well as the shaft radial runout and yaw pitch vibration angle, to address the aforementioned problems.
[0004] To achieve the above objectives, the technical solution of this application is as follows:
[0005] A detection and calibration device for calibrating a turntable shaft and its encoder includes a cylindrical lens positioned between an objective lens and a charge-coupled image sensor (CCAS). The bottom surface of the cylindrical lens is parallel to the CCAS, and the edge where the semicircular cross-section of the cylindrical lens intersects its bottom surface is parallel to the X-axis of the CCAS imaging plane. The normal vector of the CCAS is parallel to the imaging optical axis of the objective lens. A fluorescence excitation source is fitted around the objective lens. The objective lens, CCAS, cylindrical lens, and fluorescence excitation source constitute a fluorescence microscope with a fixed spatial position. Three fluorescent microspheres are fixed on a planar substrate, arranged in a triangular pattern, with varying intervals on the order of millimeters.
[0006] Optionally, among the three fluorescent microspheres, the fluorescent microsphere corresponding to the intersection of the longest and second longest interval segments is the first fluorescent microsphere, the fluorescent microsphere corresponding to the intersection of the longest and shortest interval segments is the second fluorescent microsphere, and the fluorescent microsphere corresponding to the intersection of the second longest and shortest interval segments is the third fluorescent microsphere.
[0007] Optionally, the substrate is fixed in parallel on a six-dimensional calibration stage, and the six-dimensional calibration stage with the substrate is located under a fluorescence microscope.
[0008] Optional, the six-dimensional calibration displacement stage includes: a six-dimensional precision calibration displacement stage.
[0009] Optionally, the substrate is fixed on a micro-adjustment stage, which is fixed on the turntable shaft of the turntable being calibrated.
[0010] Optionally, the fluorescence microscope is fixed on a six-dimensional adjustable displacement stage.
[0011] Optionally, the rotation axis of the calibrated stage is perpendicular to the imaging surface of the charge-coupled image sensor, and the rotation axis of the calibrated stage is parallel to the imaging optical axis of the fluorescence microscope.
[0012] Optional, the six-dimensional adjustment displacement stage includes: a six-dimensional precision adjustment displacement stage.
[0013] Optionally, all three fluorescent microspheres are sub-millimeter size.
[0014] Optionally, the fluorescence excitation source has a ring structure.
[0015] This application realizes a device that can simultaneously calibrate the accuracy, shaft diameter runout, and yaw pitch vibration angle of an encoder at any angle point throughout the entire cycle of a turntable, without the need for additional instruments. This enables full-cycle calibration of the encoder accuracy and shaft attitude mounted on a high-precision turntable, laying the necessary technical foundation for improving the accuracy and stability of the turntable, and is easy to operate.
[0016] To make the above-mentioned features and advantages of the application more apparent and understandable, specific embodiments are provided below, and detailed descriptions are given in conjunction with the accompanying drawings. Attached Figure Description
[0017] Figure 1 A three-dimensional measurement and calibration schematic diagram of the detection and calibration device for calibrating the turntable shaft and its encoder provided in this application.
[0018] Figure 2 This is a schematic diagram of a substrate 10 with three fluorescent microspheres fixed on a six-dimensional precision calibration displacement stage 11.
[0019] Figure 3This is a schematic diagram illustrating the calibration of the turntable shaft and its encoder using a fluorescence microscope.
[0020] In the figure: 1 Objective lens, 2 Cylindrical lens, 3 Charge-coupled image sensor, 4 Imaging optical axis, 5 Fluorescent excitation source, 6 Fluorescent microscope, 7 Fluorescent microsphere, 8 Fluorescent microsphere, 9 Fluorescent microsphere, 10 Substrate, 11 Six-dimensional precision calibration stage, 12 Focal longitudinal plane, 13 Calibrated turntable, 14 Turntable axis, 15 Rotation axis, 16 Six-dimensional precision adjustment stage, 17 Micro-adjustment stage.
[0021] In the accompanying drawings, similar reference numerals refer to the same elements. Detailed Implementation
[0022] To make the objectives and technical solutions of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.
[0023] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings.
[0024] This application provides a detection and calibration device for calibrating a turntable shaft and its encoder, used to detect and calibrate the turntable shaft and its encoder to be calibrated.
[0025] Please see Figure 1 , Figure 1 This is a three-dimensional measurement and calibration schematic diagram of the detection and calibration device for calibrating the turntable shaft and its encoder provided in this application. The cylindrical lens 2 is located between the objective lens 1 and the 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 plane of the CCD 3. The normal vector of the CCD 3 is parallel to the imaging optical axis of the objective lens 1. A ring-shaped fluorescence excitation source 5 is fitted on the outside of the objective lens 1. The objective lens 1, the CCD 3, the cylindrical lens 2 and the fluorescence excitation source 5 constitute a fluorescence microscope 6 with a fixed spatial position. Three sub-millimeter-sized fluorescent microspheres are fixed on a planar substrate 10. The three fluorescent microspheres are distributed in a triangle. The spacing between the three fluorescent microspheres is unequal and on the order of millimeters.
[0026] As an example, among the three fluorescent microspheres, the fluorescent microsphere corresponding to the intersection of the longest and second longest interval segments is denoted as fluorescent microsphere 7, the fluorescent microsphere corresponding to the intersection of the longest and shortest interval segments is denoted as fluorescent microsphere 8, and the fluorescent microsphere corresponding to the intersection of the second longest and shortest interval segments is denoted as fluorescent microsphere 9.
[0027] In one embodiment of this application, the substrate 10 is fixed in parallel to a six-dimensional calibration displacement stage, which includes a six-dimensional precision calibration displacement stage 11; please refer to Figure 2 , Figure 2 This is a schematic diagram of a substrate 10 with three fluorescent microspheres fixed on a six-dimensional precision calibration displacement stage 11.
[0028] In this embodiment, the six-dimensional precision calibration displacement stage 11 with substrate 10 is located under the fluorescence microscope 6.
[0029] As an example, the displacement motion of the six-dimensional precision calibration displacement stage 11 includes: translational motion with two non-parallel motion directions.
[0030] The following will continue to combine Figure 1 and Figure 2 This application outlines the workflow:
[0031] The fluorescence microscope 6 has a scattering imaging function. After the fluorescence excitation light source 5 is turned on, the excitation beam can be incident on the spatial area under the objective lens 1 and irradiate the three fluorescent microspheres, thereby causing them to emit fluorescence, so that the three fluorescent microspheres can be imaged on the charge-coupled image sensor 3.
[0032] Furthermore, the imaging of the three fluorescent microspheres is fitted with a two-dimensional Gaussian function. This not only yields the centroid position of each microsphere's imaging, but also the width of the light intensity distribution along the X and Y axes of the imaging plane of the charge-coupled image sensor 3, thus obtaining the XY-axis width ratio, i.e., the width ratio in the X and Y axes. On different longitudinal planes, i.e., the imaging plane perpendicular to the imaging optical axis 4, the width ratio in the X and Y axes of the astigmatic imaging by the cylindrical lens 2 is different. The six-dimensional precision calibration stage 11 is made to perform two non-parallel translational movements. A fluorescent microsphere is selected, and the three XY-axis width ratios corresponding to the three images before and after the movement on the charge-coupled image sensor 3 are obtained. If the three XY-axis width ratios are the same, it indicates that the plane determined by the two translational movement directions is a longitudinal plane of the fluorescence microscope 6. The pitch and yaw attitudes of the six-dimensional precision calibration stage 11 are traversed with the minimum step size. The above translational motion is performed in each attitude case, and the width ratios of the three XY axes corresponding to the selected fluorescent microspheres are obtained. The attitude vector (m,n,q) of the six-dimensional precision calibration stage 11 when the three XY axis width ratios are the same is found as the vector value in the motion coordinate system of the six-dimensional precision calibration stage 11. This vector value is the normal vector of a determined longitudinal object surface, and it is also the imaging optical axis 4 vector.
[0033] Furthermore, the six-dimensional precision calibration stage 11 is moved back and forth along the attitude vector (m,n,q), and imaging is performed on fluorescent microspheres 7, 8, and 9. The functional relationship between the different longitudinal plane heights of each fluorescent microsphere at the relative focal longitudinal plane 12 and the XY axis width of the imaging of that fluorescent microsphere can be obtained. Let f be the longitudinal plane height function of the three fluorescent microspheres. A (w A ), f B (w B ) and f C (w C ), where w A w B and w C These represent the XY axis width ratios of fluorescent microspheres 7, 8, and 9, respectively. Further, the six-dimensional precision calibration stage 11 is translated by one displacement value on each longitudinal surface. The displacement measurement value of each fluorescent microsphere is obtained on the charge-coupled image sensor 3. Dividing each fluorescent microsphere displacement measurement value by the displacement value of the six-dimensional precision calibration stage 11 yields the micromagnification value on each longitudinal surface. The micromagnification value varies depending on the height of the longitudinal surface and is a function related to the height of the longitudinal surface or the XY axis width ratio of the fluorescent microsphere imaging. The micromagnification functions for the three fluorescent microspheres are denoted as N. A (w A ), NB (w B ) and N C (w C ).
[0034] In another embodiment of this application, please refer to Figure 3 , Figure 3 This diagram illustrates the calibration of six pairs of calibrated turntable shafts and their encoders using a fluorescence microscope.
[0035] As an example, the substrate 10 is fixed on a micro-adjustment stage 17, which is fixed on the turntable shaft 14 of the calibrated turntable 13.
[0036] In this embodiment, the fluorescence microscope 6 is fixed on a six-dimensional adjustment stage, which includes a six-dimensional precision adjustment stage 16; the substrate 10 with three fluorescent microspheres is fixed on a micro-adjustment stage 17, which is fixed on the rotation axis 14 of the calibrated turntable 13.
[0037] As an example, the rotation axis 15 of the calibrated turntable 13 is perpendicular to the imaging surface of the charge-coupled image sensor 3.
[0038] As an example, the rotation axis 15 of the calibrated turntable 13 is parallel to the imaging optical axis 4 of the fluorescence microscope 6.
[0039] The following will continue to combine Figure 3 The workflow of this embodiment is as follows:
[0040] Start the calibrated turntable 13 to rotate the turntable shaft 14 one revolution. Ensure that all three fluorescent microspheres can be imaged by the fluorescence microscope 6 during the rotation of the turntable shaft 14. If any fluorescent microsphere is not imaged, the micro-adjustment stage 17 needs to be adjusted until all fluorescent microspheres can be imaged.
[0041] Furthermore, after confirming that all fluorescent microspheres can be imaged, the calibrated turntable 13 is restarted, and the turntable axis 14 of the calibrated turntable 13 is rotated by a minimum step angle and then stationary. Then, the imaging of each fluorescent microsphere by the fluorescence microscope 6 is recorded. By fitting the imaging light intensity with a two-dimensional Gaussian function, the centroid coordinates of each fluorescent microsphere in the imaging plane coordinates of the charge-coupled image sensor 3 and the imaging XY axis width ratio are obtained. By the imaging XY axis width ratio of each fluorescent microsphere, the micromagnification function value corresponding to the longitudinal object height of each fluorescent microsphere can be found. The imaging centroid coordinates are divided by the micromagnification function value to obtain the spatial plane coordinates of each fluorescent microsphere mapped to the imaging plane coordinates of the charge-coupled image sensor 3. Select a fluorescent microsphere. After the turntable axis 14 rotates one revolution, a series of different spatial plane coordinate values of the selected fluorescent microsphere can be obtained. These data are fitted with a general elliptic function with the major and minor axes of the ellipse not parallel to the coordinate axes. The fitted ellipse is the spatial trajectory of the plane mapped by the fluorescent microsphere when the turntable axis 14 rotates. The length values of the major and minor axes of the fitted ellipse are recorded at this time. The pitch and yaw attitudes of the six-dimensional precision adjustment stage 16 are traversed with the minimum step size. The turntable is rotated once for each attitude, so that a length value of the major and minor axes of the fitted ellipse can be obtained for each attitude. When the major and minor axes of the fitted ellipse corresponding to a certain attitude are the minimum values of all traversed attitudes, that is, when the rotation axis 15 is perpendicular to the imaging plane of the charge-coupled image sensor 3, the length of the mapped spatial plane trajectory is the shortest. At this time, the rotation axis 15 of the turntable is parallel to the imaging optical axis 4 of the fluorescence microscope 6.
[0042] Further, 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 axis 14 one revolution. After each minimum step angle, it remains stationary, and the imaging data of the fluorescence microscope 6 is recorded. The angular position of the turntable axis 14 at the start is recorded as the starting position. Since the spatial coordinate system of the three fluorescent microspheres 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 longitudinal object plane 12 of the focal point, that is, the spatial plane coordinate values on the imaging surface of the charge-coupled image sensor 3 are equal to the spatial plane coordinate values on the XY axis plane of the fluorescent microsphere spatial coordinate system, the spatial plane coordinate values on the imaging surface of the three charge-coupled image sensors 3 are obtained. Adding the longitudinal object plane height function values of the three fluorescent microspheres, the spatial three-dimensional coordinate values of each fluorescent microsphere are obtained. Through the spatial three-dimensional coordinate values of these three fluorescent microspheres, the spatial distance between the three fluorescent microspheres can be obtained, 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 ), (xB启 ,y B启 , z B启 ) and (x C启 ,y C启 , z C启 Furthermore, from the three-dimensional spatial coordinates of the three fluorescent microspheres, the spatial coordinates of the foot of the perpendicular from fluorescent microsphere 9 to the spatial line determined by fluorescent microspheres 7 and 8 can be obtained. The spatial coordinates of the foot of the perpendicular are denoted as (x...). N启 ,y N启 , z N启 ), which means as follows:
[0043]
[0044] Specifically, the spatial straight line α determined by fluorescent microspheres 7 and 8 AB启 And fluorescent microspheres 9 with foot (x N启 ,y N启 , z N启 The spatial line α determined by ) CN启 The angles between the fluorescent microsphere and its Y-axis on the YZ-plane of the spatial coordinate system are expressed as follows:
[0045]
[0046] Specifically, the spatial straight line β determined by fluorescent microspheres 7 and 8 AB启 And fluorescent microspheres 9 with foot (x N启 ,y N启 , z N启 The spatial line β determined by ) CN启 The angles between the fluorescent microsphere and its X-axis on the XZ plane of the spatial coordinate system are expressed as follows:
[0047]
[0048] Therefore, in the spatial coordinate system of the fluorescent microspheres, when the turntable axis 14 is in the initial position, the angle between the plane of the substrate 10 with three fluorescent microspheres and the X-axis, i.e., the initial sway angle, is α. AB启 +α CN启 The angle between the plane of the substrate 10 with three fluorescent microspheres and the Y-axis, i.e., the initial pitch angle, is β. AB启 +β CN启 .
[0049] Furthermore, the turntable axis 14 rotates one revolution at a minimum step angle, and a series of three-dimensional spatial coordinates of each fluorescent microsphere in the spatial coordinate system are recorded at each rotation step angle of the turntable axis. These three-dimensional spatial coordinates of each fluorescent microsphere are then uniformly labeled as (x... A ,y A , z A), (x B ,y B , z B ) and (x C ,y C , z C The XY plane coordinates (x, y, y) of the three fluorescent microspheres were then plotted. A ,y A ), (x B ,y B ) and (x C ,y C Perform planar elliptic function fitting on each, select the fitted ellipse with the largest major axis and its corresponding fluorescent microsphere, and obtain the coordinates of the central plane of the fitted ellipse as (x... o ,y o ), and the coordinates of any point on the selected fitted elliptic function from the center of the ellipse (x o ,y o Let θ be the angle between the line connecting the two points and the major axis of the ellipse, and denote this angle as θ at the initial position. 启 Record the encoder angle value as δ when each turntable axis rotates by a step angle of 14, and record the encoder angle value as δ at the starting position. 启 , (θ-θ 启 ) and (δ-δ 启 The difference between the values is the calibration data for the turntable encoder accuracy within a complete rotation cycle. The XY-axis plane coordinates of the selected fluorescent microsphere corresponding to the rotation step angle of each turntable axis 14 are then compared to (x...). o ,y o The distance from the selected fitted elliptic function point (x, y) to the center of the ellipse (x, y) at this angle. o ,y o The difference in distance constitutes the radial runout data of the turntable shaft 14 within one complete rotation cycle. A -z A启 or z B -z B启 or z C -z C启 This refers to all the axial runout data within a complete rotation cycle corresponding to the rotation step angle of each turntable axis 14. Similar to step S7, the yaw angle α corresponding to the rotation step angle of each turntable axis 14 can be obtained. AB +α CN and pitch angle β AB +β CN α AB +α CN -α AB启 -α CN启 and β AB +β CN -β AB启 -β CN启This is the calibration data for the yaw and pitch vibration angles over a complete rotation cycle, where α AB α represents the spatial straight line determined by fluorescent microspheres 7 and 8 corresponding to the rotation step angle of each turntable axis 14. CN This indicates the fluorescent microsphere 9 and the foot (x) corresponding to the rotation step angle of each turntable axis 14. N ,y N , z N The spatial line determined by β AB This represents the spatial straight line determined by fluorescent microspheres 7 and 8 corresponding to the rotation step angle of each turntable axis 14, β. CN This indicates the fluorescent microsphere 9 and the foot (x) corresponding to the rotation step angle of each turntable axis 14. N ,y N , z N The spatial straight line determined by ).
[0050] This application realizes a device that can simultaneously calibrate the accuracy, shaft diameter runout, and yaw pitch vibration angle of an encoder at any angle point throughout the entire cycle of a turntable, without the need for additional instruments. This enables full-cycle calibration of the encoder accuracy and shaft attitude mounted on a high-precision turntable, laying the necessary technical foundation for improving the accuracy and stability of the turntable, and is easy to operate.
[0051] Although this application has been disclosed above with reference to embodiments, it is not intended to limit this application. Anyone skilled in the art may make some modifications and refinements without departing from the spirit and scope of this application. Therefore, the scope of protection of this application shall be determined by the appended claims.
Claims
1. A detection and calibration device for calibrating a turntable shaft and its encoder, characterized in that, A cylindrical lens is located 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. The edge where the semicircular cross section of the cylindrical lens intersects with its bottom surface 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 fluorescent excitation source is fitted on the outside of the objective lens. An objective lens, a charge-coupled image sensor, a cylindrical lens, and a fluorescence excitation source constitute a fluorescence microscope with a fixed spatial position; three fluorescent microspheres are fixed on a planar substrate, the three fluorescent microspheres are distributed in a triangle, and the spacing between the three fluorescent microspheres is unequal, all on the order of millimeters.
2. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 1, characterized in that, Of the three fluorescent microspheres, the fluorescent microsphere corresponding to the intersection of the longest and second longest interval segments is the first fluorescent microsphere, the fluorescent microsphere corresponding to the intersection of the longest and shortest interval segments is the second fluorescent microsphere, and the fluorescent microsphere corresponding to the intersection of the second longest and shortest interval segments is the third fluorescent microsphere.
3. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 1, characterized in that, The substrate is fixed in parallel on a six-dimensional calibration stage, which is located under a fluorescence microscope.
4. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 3, characterized in that, The six-dimensional calibration displacement stage includes: a six-dimensional precision calibration displacement stage.
5. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 1, characterized in that, The substrate is fixed on a micro-adjustment stage, which is fixed on the rotation axis of the calibrated turntable.
6. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 5, characterized in that, The fluorescence microscope is fixed on a six-dimensional adjustable displacement stage.
7. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 6, characterized in that, The rotation axis of the calibration stage is perpendicular to the imaging surface of the charge-coupled image sensor, and the rotation axis of the calibration stage is parallel to the imaging optical axis of the fluorescence microscope.
8. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 6, characterized in that, The six-dimensional adjustment displacement stage includes: a six-dimensional precision adjustment displacement stage.
9. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 1, characterized in that, All three fluorescent microspheres are sub-millimeter size.
10. The detection and calibration device for calibrating the turntable shaft and its encoder as described in claim 1, characterized in that, The fluorescence excitation source has a ring structure.