CN117760336B - Calibration method and medium of five-axis interference measurement system and electronic equipment - Google Patents
Calibration method and medium of five-axis interference measurement system and electronic equipment Download PDFInfo
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Abstract
The invention relates to the field of calibration, in particular to a calibration method, a medium and electronic equipment of a five-axis interference measurement system. The method comprises the following steps: and acquiring an inverse kinematics equation set of the five-axis interference measurement system under the target calibration posture. And acquiring the position information of at least two points on the surface to be measured of the first calibration auxiliary workpiece, and taking the position information as calibration information. And determining parameters d, L and L to be calibrated according to the calibration information, the inverse kinematics solution equation set and the curved surface expression of the calibration piece to obtain the complete inverse kinematics solution of the five-axis interference measurement system, and completing the calibration work. The five-axis motion system can adjust the positions of the measuring head and the workpiece to be measured at more angles so as to obtain more calibration information and improve the calibration precision of system parameters. In addition, the error between the theoretical focusing point coordinate and the actual focusing point coordinate of the five-axis interference measurement system calibrated by the calibration method disclosed by the invention can be controlled within +/-3 mu m after focusing and leveling.
Description
Technical Field
The invention relates to the field of calibration, in particular to a calibration method, a medium and electronic equipment of a five-axis interference measurement system.
Background
With the rapid development of ultra-precise machining technology, such as single-point diamond turning technology, the surface topography machining precision of the curved optical element reaches submicron level, and the curved optical element has microstructures, such as a curved microlens array, a curved fresnel lens and the like. This presents new challenges for optical element surface topography detection. For the measurement of the complex surface morphology of such optical elements, the main non-contact optical interferometry techniques are laser phase-shift interferometry (PSI) and scanning white light interferometry (CSI).
The tilt range of the interferometry measurement surface depends on the interference objective NA. As shown in fig. 1, generally, for smoother surfaces, no interference fringes will appear when the curvature of the point to be measured is high and exceeds the cone limit of the objective NA. One solution for high curvature optical element surface topography measurement is therefore to combine a white light interferometry system with a multi-axis motion system. As shown in fig. 2, the relative position of the measuring head and the workpiece and the turntable are changed through the triaxial translation table, so that the optical axis of the measuring head is ensured to be close to the normal line of the workpiece to be measured during measurement. However, for the overall shape measurement of large curved surface elements, the efficiency of a manual leveling and focusing mode is too low for all to-be-measured points, so that the automatic measurement function of the five-axis interference measurement system needs to be developed. In order to realize the automatic measurement of the five-axis interference measurement system, some unknown parameters in the system need to be calibrated so as to obtain an accurate inverse kinematics solution equation set. It is desirable to provide a highly accurate calibration method.
Disclosure of Invention
Aiming at the technical problems, the invention adopts the following technical scheme:
According to one aspect of the invention, a calibration method of a five-axis interference measurement system is provided, the five-axis interference measurement system comprises an X translational axis, a Y translational axis, a Z translational axis, a first rotating shaft, a second rotating shaft and an interference imaging measuring head, and the X translational axis, the Y translational axis and the Z translational axis are connected with each other to form a three-dimensional moving platform. The first rotating shaft is fixedly connected to the Y translational shaft. The second rotating shaft is fixedly connected to the Z translational shaft. The interference imaging measuring head is fixedly connected to the second rotating shaft.
The measuring optical axis of the interference imaging measuring head is perpendicular to the central axis of the second rotating shaft. The first rotating shaft is used for clamping a workpiece to be tested. The central axis of the first rotating shaft is perpendicular to the central axis of the second rotating shaft.
The calibration method comprises the following steps:
And controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so as to enable the five-axis interference measurement system to be in an initial calibration posture. The initial calibration posture is a posture that the central axis of the first rotary shaft and the measuring optical axis of the interference imaging measuring head are in a collinear state in the Y-axis direction.
And clamping the first calibration auxiliary workpiece on the first rotating shaft, and adjusting the installation position to enable the five-axis interference measurement system to be in a target calibration posture. The target calibration posture is a posture that the rotation axis of the first calibration auxiliary workpiece and the central axis of the first rotating shaft are in a collinear state along the Y-axis direction. The first calibration auxiliary workpiece is a symmetrical rotator. The surface to be measured of the first calibration auxiliary workpiece is an aspheric surface with a known surface type relationship, and the surface type of the surface to be measured meets the following conditions:
zw＝f(c,k,xw)
wherein c and k are respectively the curvature value and the conical coefficient corresponding to the surface to be measured.
And acquiring an inverse kinematics equation set of the five-axis interference measurement system under the target calibration posture. The inverse kinematics system of equations satisfies the following relationship:
Wherein X w,yw,zw is the distance between a certain point on the surface to be measured and the origin of the workpiece in the directions of X axis, Y axis and Z axis. The origin of the workpiece is the intersection point of the surface to be measured and the central axis of the first rotation shaft. And X, Y and Z are the distances between a certain point on the surface to be measured and the origin of the machine in the directions of the X axis, the Y axis and the Z axis respectively. The origin of the machine is the intersection of the central axis of the second rotation axis and the collinear plane. The collinear plane is a plane parallel to the XZ plane and in which the central axis of the first rotation axis is located. b is the rotation angle of the second rotation axis with respect to the Z-axis direction. d is the distance between the machine origin and the focal point of the interferometric imaging probe in the X-axis direction. l is the distance between the machine origin and the focal point of the interferometric imaging probe in the Z-axis direction. L is the distance between the machine origin and the workpiece origin in the Z-axis direction.
And acquiring the position information of at least two points on the surface to be measured of the first calibration auxiliary workpiece, and taking the position information as calibration information.
According to the calibration information, the inverse kinematics equation set and z w＝f(c,k,xw), determining parameters d, L and L to be calibrated, and generating a kinematics model of the five-axis interference measurement system to complete the calibration work.
Further, the interferometric imaging probe has an image acquisition function.
Controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that the five-axis interference measurement system is in an initial calibration posture, comprising:
The second calibration auxiliary workpiece is clamped onto the first rotating shaft, and the clamping position is adjusted so that the rotation axis of the second calibration auxiliary workpiece and the central axis of the second rotating shaft are arranged in line in the Y-axis direction. The second calibration assistance workpiece has a spherical surface.
And controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that the image of the spherical surface center point acquired by the interference imaging probe is positioned at the center of the field of view of the interference imaging probe.
Further, the spherical surface has at least one concentric circular cutting mark thereon. The center of the concentric circle tool mark and the center of the spherical surface are both positioned on the central axis of the first rotating shaft.
Controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that an image of a spherical surface center point acquired by the interference imaging probe is positioned at the center of a field of view of the interference imaging probe, comprising:
And controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move according to the relative position of the concentric circle tool mark acquired by the interference imaging probe and the field of view center of the interference imaging probe, so that the image of the spherical surface center point acquired by the interference imaging probe is positioned at the field of view center of the interference imaging probe.
Further, after controlling at least one motion axis of the X translation axis, the Y translation axis, the Z translation axis, the first rotation axis, and the second rotation axis to move so that the image of the spherical surface center point acquired by the interferometric imaging probe is located at the center of the field of view of the interferometric imaging probe, the method further includes:
and controlling the Z translation axis to move, and acquiring interference fringe images shot by the interference imaging measuring head in real time.
And verifying the initial calibration posture according to the interference fringe image.
Further, verifying the initial calibration pose according to the interference fringe image, including:
the annular interference fringes with alternate brightness exist in the fringe images, the centers of the annular interference fringes coincide with the center points of the spherical surfaces, and verification is passed.
Furthermore, annular interference fringes with alternate brightness exist in the plurality of fringe images, the centers of the annular interference fringes are not coincident with the center points of the spherical surfaces, verification fails, and the five-axis interference measurement system needs to be readjusted to be in an initial calibration posture.
Further, obtaining position information of at least two points on the surface to be measured of the first calibration auxiliary workpiece, as calibration information, includes:
And acquiring position information of four points on the surface to be measured of the first calibration auxiliary workpiece, and taking the position information as calibration information.
Further, the four points serving as calibration information are uniformly distributed on the surface to be measured on the same side of the rotation axis of the first calibration auxiliary workpiece.
According to a second aspect of the present invention, there is provided a non-transitory computer readable storage medium storing a computer program which when executed by a processor implements a calibration method of a five-axis interferometry system as described above.
According to a third aspect of the present invention, there is provided an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing a calibration method for a five-axis interferometry system as described above when executing the computer program.
The invention has at least the following beneficial effects:
The five-axis motion system can adjust the positions of the measuring head and the workpiece to be measured at more angles so as to obtain more calibration information and further improve the calibration precision of system parameters. In addition, the calibration scheme can establish a parameter equation set to be calibrated by measuring at least two arbitrary points of the high-precision first calibration auxiliary workpiece known by the curved surface equation, the parameter to be calibrated can be calculated by solving the equation, and the calibration can be completed rapidly and efficiently. Meanwhile, the error between the theoretical focusing point coordinate and the actual focusing point coordinate after focusing and leveling of the five-axis interference measurement system calibrated by the calibration method disclosed by the invention can be controlled within +/-3 mu m, and the subsequent accuracy verification experimental result can be seen in detail.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of the light between the surface of the work piece to be measured and the cone limit of the objective N A in SWLI detection technology;
FIG. 2 is a schematic diagram of a five-axis white light interferometry system according to an embodiment;
FIG. 3 is a schematic diagram of a five-axis white light interferometry system according to an embodiment;
FIG. 4 is a schematic diagram of a scanning white light interferometry head in a five-axis white light interferometry system according to an embodiment;
FIG. 5 is a schematic diagram showing the propagation of an optical path of a scanning white light interferometric probe in an embodiment;
FIG. 6 is a schematic diagram of a five-axis white light interferometry system and a first calibration aid workpiece according to an embodiment in an XY plane;
FIG. 7 is a kinematic chain topology of a five-axis white light interferometry system according to an embodiment;
FIG. 8 is a schematic diagram of a five-axis white light interferometry system and a first calibration aid in an XY plane according to another embodiment;
FIG. 9 is a schematic diagram showing the location distribution of the marked points in one embodiment;
FIG. 10 is a schematic diagram showing a position distribution of verification points in an embodiment;
FIG. 11 is a physical diagram and a tool mark schematic diagram of a second calibration auxiliary workpiece according to an embodiment;
FIG. 12 is a flow chart of a calibration method of a five-axis interferometry system according to an embodiment.
Reference numerals
1. Scanning a white light interference measuring head; 2. a first calibration auxiliary workpiece; 3. a second calibration auxiliary workpiece; 4. verifying points; 51. mirau interference objective; 52. a CCD camera; 53. PZT; 54. and a propagation light path module.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
As a possible embodiment of the present invention, as shown in fig. 2 and 3, a calibration method of a five-axis interference measurement system is provided, specifically, because other interference imaging measuring heads are the same as the calibration principle of the white light interference measuring head, the calibration is mainly performed by relying on the zero fringe phenomenon of the measuring head and the annular fringe on the spherical end of the second calibration auxiliary workpiece 3. Therefore, only the calibration of the white light interferometry head (i.e. the scanning white light interferometry head) is used for illustration in the present embodiment.
Specifically, the five-axis white light interferometry system comprises an X translational axis, a Y translational axis, a Z translational axis, a first rotating shaft, a second rotating shaft and a scanning white light interferometry head 1, wherein the X translational axis, the Y translational axis and the Z translational axis are mutually connected to form a three-dimensional moving platform. The first rotating shaft is fixedly connected to the Y translational shaft. The second rotating shaft is fixedly connected to the Z translational shaft. The scanning white light interference measuring head 1 is fixedly connected to the second rotating shaft.
The measuring optical axis of the scanning white light interference measuring head 1 is perpendicular to the central axis of the second rotating shaft. The first rotating shaft is used for clamping a workpiece to be tested. The central axis of the first rotating shaft is perpendicular to the central axis of the second rotating shaft.
The five-axis motion platform in the five-axis white light interferometry system in this embodiment may be a Moore five-axis motion platform. As shown in fig. 2 and 3, the workpiece is mounted on a vacuum chuck which is fixed on the C-axis (i.e., the first rotation axis), so that the workpiece can only rotate about its symmetry axis; the measuring head (namely the scanning white light interference measuring head 1) is arranged on the B axis (namely the second rotating shaft), and the relative posture between the measuring head and the workpiece can be changed by rotating the B axis, so that the optical axis of the measuring head can be coincident with the normal line of the point to be measured during measurement. Three spindles XYZ (i.e., X, Y, and Z spindles) can change the relative position between the workpiece and the gauge head.
The structure of the scanning white light interference probe 1 in this embodiment is shown in fig. 4, and mainly comprises four parts of a Mirau interference objective lens 51, a propagation light path module 54, a CCD (charge coupled device ) camera and a PZT53 (piezoelectric ceramic transducer, a piezoelectric ceramic transducer, that is, a piezoelectric ceramic motor). The Mirau interference objective lens is a Nikon 20X objective lens, N A is 0.40, the field size is 300X300 mu m, and the Mirau interference objective lens has the function of dividing a light beam transmitted by a light source along a light path into two beams and transmitting the two beams separately, and generating interference signals after the light beam passes through a surface to be detected and a built-in reference mirror respectively. The propagation light path module 54 is used for controlling the propagation of the light beam emitted by the light source to interfere with the Mirau interference objective lens and transmitting the interference signal to the CCD camera 52. The CCD camera 52 is used to receive the overall interference signal and image. The PZT53 has a stroke of 100 μm and is used for driving the Mirau interference objective lens to scan along the optical axis (Z axis) direction.
As shown in fig. 5, the process of generating an interference signal by the scanning white light interference probe 1 is as follows: after light is emitted from the light source, the light is transmitted through a transmission light path module 54 formed by a lens and a spectroscope, one beam irradiates a sample to be measured and is reflected, the other beam irradiates a reference mirror and is reflected, interference is generated after the two beams of reflected light meet, and an interference signal is transmitted to the CCD camera 52 after passing through the transmission light path.
When the scanning white light interference measuring head 1 performs measurement, as shown in fig. 5, the piezoelectric motor (PZT 53) drives the interference objective lens to perform equidistant scanning along the Z-axis direction and trigger the camera to collect images. And extracting interference signals of a series of two-dimensional images at the same pixel point after scanning is completed, modulating the interference signals by a rapidly attenuated coherent envelope, calculating to obtain the peak position of the coherent envelope, and finding out zero-order stripes to determine the absolute height of the surface. The scanning range of the measuring head in the invention is + -20 μm based on the focal plane as zero standard.
As shown in fig. 12, the calibration method includes the steps of:
S100: and controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so as to enable the five-axis white light interferometry system to be in an initial calibration posture. The initial calibration posture is a posture in which the central axis of the first rotation axis and the measurement optical axis of the scanning white light interferometry head 1 are in a collinear state in the Y-axis direction.
S200: the first calibration auxiliary workpiece 2 is clamped on the first rotating shaft, and the installation position is adjusted so that the five-axis white light interferometry system is in the target calibration posture. The target calibration posture is a posture that the rotation axis of the first calibration auxiliary workpiece 2 and the central axis of the first rotation shaft are in a collinear state with the measurement optical axis of the scanning white light interference measuring head 1. The first calibration auxiliary workpiece 2 is a symmetrical rotator. The surface to be measured of the first calibration auxiliary workpiece 2 is an aspheric surface with a known surface shape relationship, and the surface shape of the surface to be measured meets the following conditions:
zw＝f(c,k,xw) (1)
wherein c and k are respectively the curvature value and the conical coefficient corresponding to the surface to be measured.
The surface shape of the first calibration auxiliary workpiece 2 is known, that is, the above z w＝f(c,k,xw) is an aspheric relation function of z w with respect to x w, and the specific surface shape may be any aspheric surface shape in the prior art, which is not limited herein.
S300: and acquiring an inverse kinematics equation set of the five-axis white light interferometry system under the target calibration posture. The inverse kinematics system of equations satisfies the following relationship:
Wherein X w,yw,zw is the distance between a certain point on the surface to be measured and the origin of the workpiece in the directions of X axis, Y axis and Z axis. The origin of the workpiece is the intersection point of the surface to be measured and the central axis of the first rotation shaft. And X, Y and Z are the distances between a certain point on the surface to be measured and the origin of the machine in the directions of the X axis, the Y axis and the Z axis respectively. The origin of the machine is the intersection of the central axis of the second rotation axis and the collinear plane. The collinear plane is a plane parallel to the XZ plane and in which the central axis of the first rotation axis is located. b is the rotation angle of the second rotation axis with respect to the Z-axis direction. d is the distance between the origin of the machine and the focusing point of the scanning white light interference measuring head 1 in the X-axis direction. l is the distance between the origin of the machine and the focusing point of the scanning white light interference measuring head 1 in the Z-axis direction. L is the distance between the machine origin and the workpiece origin in the Z-axis direction.
In order to achieve automated measurement, a high-precision inverse kinematics solution of the five-axis white light interferometry system is required, and thus a kinematic model of the system needs to be studied. As shown in fig. 6, the five-axis white light interferometry system B is set to an initial state when the axis rotation angle is 0 (the probe optical axis is parallel to the workpiece rotation axis), and the coordinates of the remaining three translational axes and the rotation axis C are set to 0. The coordinate system of the five-axis white light interferometry system is set as follows:
Machine coordinate system MCS (O mXmYmZm): the machine origin is defined on the intersection point of a plane passing through the optical axis and parallel to the XZ plane and the B-axis rotation axis, the positive direction of the X-axis is vertically downward, the positive direction of the Z-axis is horizontally rightward, the Y-axis is orthogonal to the X-axis and the Z-axis, and the positive direction is vertical to the paper surface.
A coordinate system XCS(OxXxYxZx),YCS(OyXyYyZy),ZCS(OzXzYzZz),BCS(ObXbYbZb),CCS(OcXcYcZc), for each of the XYZBC axes is fixedly attached to each axis motion stage. For ease of calculation, the coordinate system of the five axes at the initial state XYZBC is coincident with the machine coordinate system.
B-axis coordinate system BCS (O bXbYbZb): is fixedly connected to the B-axis rotating shaft, and the B-axis coordinate system coincides with the machine coordinate system in the initial state
Z-axis coordinate system ZCS (O zXzYzZz): is fixedly connected to a Z-axis translational shaft, and the Z-axis coordinate system coincides with a machine coordinate system in an initial state
Y-axis coordinate system YCS (O yXyYyZy): is fixedly connected to a Y-axis translational shaft, and the Y-axis coordinate system coincides with the machine coordinate system in an initial state
X-axis coordinate system XCS (O xXxYxZx): is fixedly connected to an X-axis translational shaft, and the X-axis coordinate system coincides with a machine coordinate system in an initial state
C-axis coordinate system CCS (O cXcYcZc): is fixedly connected to the C-axis rotating shaft, and the C-axis coordinate system coincides with the machine coordinate system in the initial state
Workpiece coordinate system WCS (O wXwYwZw): is fixedly connected with a part, the origin of the workpiece is established on the intersection point of the rotation symmetry axis of the workpiece (namely the first calibration auxiliary workpiece 2) and the surface of the workpiece, and the positive direction of each axis is the same as the machine coordinate system
Gauge head coordinate system TCS (O tXtYtZt): a virtual coordinate system is established on the focus of the scanning white light interference measuring head 1, the Z axis is defined as the optical axis direction, and the X axis direction and the Y axis direction are the same as the X axis direction and the Y axis direction of the machine coordinate system in the initial state.
In this embodiment, a kinematic chain topology diagram of the whole five-axis white light interferometry system is shown in fig. 7, and the kinematic model of the system can be established by analyzing the relationship between the focal point of the measuring head and the coordinate coincidence of the point to be measured, which coincides with the focal point of the measuring head, on the workpiece under the machine coordinate system.
Assuming that the coordinate and initial posture of the focusing point of the measuring head are P t under the coordinate system of the measuring head, and assuming that the coordinate and initial posture of the point to be measured, which are coincident with the focusing point of the measuring head, on the workpiece are P w under the coordinate system of the workpiece, then:
In equation 2, x w,yw and z w are coordinates of the point to be measured in three directions XYZ in the workpiece coordinate system, and i w,jw and k w together represent a direction vector of the point to be measured connecting with the origin of the workpiece coordinate system.
The static bias matrix from the coordinate system of the measuring head to the coordinate system of the B axis is set as T BT_S, and the dynamic motion matrix is set as T BT_M. Let the static bias matrix from the workpiece coordinate system to the C-axis coordinate system be T CW_S and the dynamic motion matrix be T CW_M. Because the measuring head is fixed on the B-axis turntable, the workpiece is fixed on the C-axis through the clamp, and no relative movement exists, so that T BT_M＝TCW_M =i. I is a 4X4 identity matrix, and T BT_S and T CW_S are:
As can be seen from fig. 5, d is the vertical distance from the center point of the B-axis turntable to the optical axis of the scanning white light interference measuring head 1; l is the distance between the focusing point of the scanning white light measuring head and the center point of the B-axis turntable and the drop foot of the optical axis of the scanning white light interference measuring head 1; l is the offset distance between the origin of the machine coordinate system and the origin of the workpiece coordinate system in the Z direction in the initial state.
Similarly, a static bias matrix from the B-axis coordinate system to the Z-axis coordinate system is set as T ZB_S, and a dynamic motion matrix is set as T ZB_M. Let the static bias matrix from the C-axis coordinate system to the Y-axis coordinate system be T YC_S, and the dynamic motion matrix be T YC_M. Since the Y-axis coordinate system, the C-axis coordinate system, and the Z-axis coordinate system coincide with the B-axis coordinate system in the initial state, T ZB_S＝TYC_S =i. Let C be the angle of rotation of the C axis, B be the angle of rotation of the B axis, both in the counterclockwise direction, then T ZB_M and T YC_M are:
Let the static bias matrix from the X-axis coordinate system to the machine coordinate system be T MX_S and the dynamic motion matrix be T MX_M. Let the static bias matrix from the Y-axis coordinate system to the X-axis coordinate system be T XY_S, and the dynamic motion matrix be T XY_M. Let the static bias matrix from the Z-axis coordinate system to the machine coordinate system be T MZ_S and the dynamic motion matrix be T MZ_M. Since the XYZ three-axis coordinate system coincides with the machine coordinate system in the initial state, T MX_S＝TXY_S＝TMZ_S =i, assuming that x, y, and z are XYZ three-axis motion amounts, respectively, T MX_M,TXY_M and T MZ_M are:
the coordinates of the measuring head focal point and the point to be measured, which coincides with the measuring head focal point, on the workpiece in the machine coordinate system are respectively And/>The homogeneous coordinate conversion relation can be obtained by:
in the course of the measurement of the system, And/>Should be coincident under the machine coordinate system, inherent:
solving equation 8 can obtain the inverse kinematics solution equation set of the five-axis white light interferometry system as follows:
After the inverse solution of the rotation angle of the double turntable is obtained, the motion amount of the triaxial translational axis is known from the equation set 9 and is also related to the unknown parameters d, L. To obtain a high-precision inverse kinematics solution, these three key parameters need to be calibrated.
S400: position information of at least two points on the surface to be measured of the first calibration auxiliary workpiece 2 is acquired as calibration information.
Specifically, as shown in fig. 9, position information of four points on the surface to be measured of the first calibration auxiliary workpiece 2 is obtained as calibration information, and the position information is five key coordinate values of the corresponding points. And the four points serving as calibration information are uniformly distributed on the surface to be measured on the same side of the rotation axis of the first calibration auxiliary workpiece 2. In order to prevent the first calibration auxiliary workpiece 2 from being affected by a machining error during machining, which may result in a final calibration result, it is necessary to disperse positions of several points as much as possible when the calibration information is selected on the surface to be measured of the first calibration auxiliary workpiece 2.
As can be seen from equation 9 of inverse kinematics, the calibration of the whole system is to confirm three key parameters d, L. Transforming equation 9 yields the system of equations:
Here, to simplify the equation set 10, we lock the C-axis at the initial state (i.e., the target calibration posture, where c=0) during calibration, and then the C-axis is not rotated during calibration, so the equation set can be simplified as:
before calibration, the probe optical axis may be aligned in the Y-axis direction to the C-axis turret swivel axis, after which the Y-axis is no longer moving, i.e. Y w =y=0.
When the optical axis of the measuring head is regulated to coincide with the C-axis rotating axis in the Y-axis direction, the problem can be simplified from a three-dimensional space to a two-dimensional XZ plane. As shown in fig. 8, the entire system can be plotted on the XZ plane. For any one measuring point, when the axes are moved so that the focal point of the measuring head almost coincides with the measuring point and the optical axis is consistent with the normal line of the measuring point on the surface of the workpiece, the zero stripe phenomenon can be seen in the field of view of the camera. After the zero streak phenomenon is seen when a certain measuring point is measured, if the coordinates x and z of the point in a machine coordinate system, the rotating angle B of the B-axis turntable and the five parameters x w and z w in a workpiece coordinate system can be known, two sets of equations about the key parameters d, L and L can be obtained from the equation set 11. There are three unknowns and thus the parameters d, L can be calibrated using at least two different measurement points. In this embodiment, 4 different measurement points, that is, 4 calibration information are selected for calibration.
In the calibration process, the positioning accuracy of the Moore five-axis motion platform is very high, specifically, in the calibration process, the positioning accuracy of three linear motion axes of the Moore five-axis motion platform is 0.3 μm in the full stroke range, and is two orders of magnitude smaller than the scanning range of tens of micrometers of the measuring head, and the positioning accuracy of the B-axis turntable is 2arc, so that the coordinates read from the corresponding upper computer system can be approximately considered to be the rotation angles B of the x-axis and the z-axis of the measuring point under the machine coordinate system.
The coordinates x w and z w of the point to be measured in the workpiece coordinate system can be determined according to the surface expression (1) of the surface to be measured of the first calibration auxiliary workpiece 2.
In the formula 1, C=1/R, and R is the curvature radius of the curved surface vertex; k= -e 2, e is the eccentricity of the curved surface. Since the surface expression is known, C and K are known constants and the surface equation is simply a function of x w.
Under this condition, we first derive the curvature at point X w for the surface equation with respect to X w, and find the arctangent to the curvature value to obtain the inclination angle between the tangent corresponding to the point and the X-axis direction, which should be equal to the angle B of rotation of the B-axis. Thus, solving equation 12 yields the coordinate x w,xw of the calibration point in the workpiece coordinate system, and then substituting the coordinate x w,xw into the surface expression 17 to obtain the coordinate z w of the calibration point in the workpiece coordinate system.
tan-1(f(C,K,xw))＝b (12)
When knowing the five values corresponding to the selected calibration points, two equations for the parameters d, L to be calibrated can be obtained.
In this embodiment, as shown in fig. 9, we select four calibration points, and obtain the five coordinate values corresponding to each calibration point by the above method to obtain 8 equations about d, L and L.
For ease of computation, we write in the form of a matrix:
AMpara＝B (13)
Wherein A is:
b i in equation 14 is the angle by which the B axis rotates when the i-th index point finds zero striping.
M para is a parameter matrix to be calibrated:
Mpara＝[d l L]T (15)
wherein d, L and L are three parameters to be calibrated.
Beta is:
B＝[xw1-x1 zw1-z1 xw2-x2 zw2-z2 xw3-x3 zw3-z3 xw4-x4 zw4-z4]T (16)
Wherein X wi and Z wi are coordinate values of the X and Z directions under the coordinate system of the workpiece after the zero fringe phenomenon is found at the ith calibration point, and X i and Z i are coordinate values of the X and Z directions under the coordinate system of the machine after the zero fringe phenomenon is found at the ith calibration point. After five key coordinate values corresponding to the four calibration points are obtained, matrices a and B can be obtained, and then the substitute calibration parameter matrix M para can be obtained by equation 13 as follows:
Mpara＝[d l L]T＝pinv(A)B (17)
In equation 17, pinv (a) represents the pseudo-inverse of matrix a.
S500: and determining parameters d, L and L to be calibrated according to the calibration information, the inverse kinematics equation set and z w＝f(c,k,xw to generate a kinematics model of the five-axis white light interferometry system so as to complete the calibration work.
Specifically, in this embodiment, a high-precision aspheric member with a caliber of 310mm, which is known as a curved surface expression, is selected as the first calibration auxiliary workpiece 2. As shown in fig. 9, first, we adjust the rotation axis of the first calibration auxiliary workpiece 2 to coincide with the axis of the C-axis turntable, then we select four points as calibration points (point 1 to point 4), and respectively move the five-axis system to the corresponding 4 points to be measured (calibration points) and find the zero streak phenomenon (when the focal point of the measuring head coincides with the point to be measured and the optical axis of the measuring head coincides with the surface normal of the point to be measured of the workpiece).
When the four calibration points find zero stripe phenomenon by calculating and reading the upper computer coordinates, the corresponding four coordinate parameters and the rotating angle B of the B-axis turntable, and the five key coordinate values of the four points are shown in table 1:
TABLE 1
From equation 14, equation 16 and Table 1, a matrix A can be obtained as:
b is:
B＝[-93.6398 29.5067 -73.9914 19.0945 -54.7871 11.0661 -23.9294 2.1352]T (19)
Thus, the parameter matrix M para to be calibrated can be obtained as:
Mpara＝[d l L]T＝[25.7156 232.7352 230.9519]T (20)
Therefore, the vertical distance d between the center point of the B-axis turntable and the optical axis is 25.7156mm, the distance L between the focal point of the measuring head and the perpendicular foot of the center of the B-axis turntable and the optical axis is 232.7352mm, and the offset distance L between the origin of the workpiece coordinate system and the origin of the machine coordinate system in the Z direction in the initial state is 230.9519mm.
Therefore, the calibration work of the five-axis white light interferometry system is completed, and the error between the theoretical focusing point coordinate and the actual focusing point coordinate of the calibrated five-axis white light interferometry system after focusing and leveling can be controlled within +/-3 mu m, and the verification result can be seen specifically.
Specifically, the calibrated parameters are substituted into an inverse kinematics solution equation set of the system, then a specific point is selected, each axis theoretical coordinate for finding the zero stripe phenomenon is calculated by the inverse kinematics solution equation set, each axis is moved to the calculated theoretical coordinate, if the zero stripe phenomenon is not found, the Z axis is finely adjusted until the zero stripe phenomenon is found, the actual Z axis coordinate value at the moment is recorded, and the Z-direction error is obtained by subtracting the actual Z axis coordinate value from the theoretical Z axis coordinate value.
As shown in fig. 10, six points were selected at 20 mm gradient from x w =40 mm, one point at each of the edge x w =150 mm and the curvature intermediate portion x w =90 mm of the part to be measured, and a total of 8 verification points 4 were selected.
Solving and solving theoretical coordinates of the eight verification points 4 by using an inverse kinematics solution equation set obtained by calibrating the parameters, then moving each axis to the theoretical coordinates, fine-tuning a Z axis if necessary until a zero stripe phenomenon is found, and recording the theoretical Z-direction coordinates, the actual Z-direction coordinates and error values thereof. Further, the theoretical coordinate values in the Z direction of eight verification points 4 and the corresponding actual coordinate values and errors when the zero stripe phenomenon is found are obtained, as shown in table 2:
TABLE 2
As can be seen from the verification results in Table 2, the inverse kinematics solution equation set obtained by the three key parameters d, L and L calibrated by the calibration method is that when each verification point 4 obtained by the solution finds the zero stripe phenomenon, the errors of the actual coordinate value and the calculated theoretical coordinate value are all within + -3 μm. And meanwhile, the Z-direction scanning range of the measuring head is +/-20 mu m during the measurement of the scanning white light measuring head, so that the measuring requirement of the measuring head is met.
On the basis of the calibration precision, a manuscript high-precision motion control model of the five-axis white light interferometry system can be established, for any to-be-measured point on a workpiece, each axis can be controlled to move by the calibrated motion control model, so that a measuring head directly moves to a theoretical position which is inverse-solved in kinematics, at the moment, the optical axis of the measuring head is close to the normal line of the to-be-measured point on the surface of the workpiece, and complete and effective interference signals can be obtained in a scanning range, further, the surface morphology of the to-be-measured point is analyzed, and automatic measurement of any to-be-measured point on the workpiece is realized.
As another possible embodiment of the present invention, the scanning white light interferometry head 1 has an image acquisition function.
S100: controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that the five-axis white light interferometry system is in an initial calibration attitude, comprising:
S101: the second calibration assistance work piece 3 is clamped to the first rotation shaft, and the clamping position is adjusted so that the rotation axis of the second calibration assistance work piece 3 is arranged in line with the center axis of the first rotation shaft. The second calibration assistance workpiece 3 has a spherical surface.
Specifically, as shown in fig. 11, the second calibration auxiliary workpiece 3 has at least one concentric circular tool mark on the spherical surface. The center of the concentric circle tool mark and the center of the spherical surface are both positioned on the central axis of the first rotating shaft. The spherical surface is a standard spherical piece with a diameter of 13mm, and the surface is provided with a single-point diamond turning leaving a circular knife grain, which can be used for assisting in confirming the spherical crown point (namely, the spherical center point).
S111: and controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move according to the relative position of the concentric circle tool mark acquired by the scanning white light interference measuring head 1 and the center of the field of view of the scanning white light interference measuring head 1, so that the image of the spherical surface center point acquired by the scanning white light interference measuring head 1 is positioned at the center of the field of view of the scanning white light interference measuring head 1.
S102: and controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that an image of a spherical surface center point (an image corresponding to a spherical crown point) acquired by the scanning white light interference measuring head 1 is positioned at the center of a field of view of the scanning white light interference measuring head 1.
The alignment scheme in this embodiment is that a high-precision standard spherical surface (namely, a second calibration auxiliary workpiece 3) is installed in the center of a vacuum chuck of the system before the first calibration auxiliary workpiece 2 is installed in the five-axis white light interferometry system. The circular ring-shaped tool grain left by single-point diamond turning on the spherical surface can be used for assisting in confirming whether the measuring point is a spherical crown point or not. The confirmation method is as follows: the position of the second calibration auxiliary workpiece 3 is adjusted first, and when an image corresponding to a spherical crown point in the image acquired by the CCD camera 52 is positioned at the center of the field of view of the scanning white light interference measuring head 1, the second calibration auxiliary workpiece 3 is confirmed to enable the symmetry rotation axis of the second calibration auxiliary workpiece 3 to coincide with the rotation axis of the C-axis turntable.
S103: and controlling the Z translation axis to move, and acquiring interference fringe images shot by the scanning white light interference measuring head 1 in real time.
S104: and verifying the initial calibration posture according to the interference fringe image.
Specifically, S104 includes:
S114: the annular interference fringes with alternate brightness exist in the fringe images, the centers of the annular interference fringes coincide with the center points of the spherical surfaces, and verification is passed.
S115: the annular interference fringes with alternate brightness exist in the fringe images, the centers of the annular interference fringes are not coincident with the center points of the spherical surfaces, verification fails, and the five-axis white light interferometry system is required to be readjusted to be in an initial calibration posture.
During verification, the probe is moved in the Z-axis direction until an annular interference fringe is observed in the CCD camera 52 and the center of the annular moire is located at the center of the field of view, at which point it is indicated that the probe optical axis coincides with the C-axis turntable rotation axis in the Y-axis direction. In the embodiment, whether the optical axis of the measuring head is coincident with the rotating shaft of the C-axis turntable or not is confirmed through two modes of knife lines and annular interference fringes, so that the coincidence precision is improved.
Furthermore, although the steps of the methods in the present disclosure are depicted in a particular order in the drawings, this does not require or imply that the steps must be performed in that particular order, or that all illustrated steps be performed, to achieve desirable results. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step to perform, and/or one step decomposed into multiple steps to perform, etc.
From the above description of embodiments, those skilled in the art will readily appreciate that the example embodiments described herein may be implemented in software, or may be implemented in software in combination with the necessary hardware. Thus, the technical solution according to the embodiments of the present disclosure may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (may be a CD-ROM, a U-disk, a mobile hard disk, etc.) or on a network, including several instructions to cause a computing device (may be a personal computer, a server, a mobile terminal, or a network device, etc.) to perform the method according to the embodiments of the present disclosure.
In an exemplary embodiment of the present disclosure, an electronic device capable of implementing the above method is also provided.
Those skilled in the art will appreciate that the various aspects of the invention may be implemented as a system, method, or program product. Accordingly, aspects of the invention may be embodied in the following forms, namely: an entirely hardware embodiment, an entirely software embodiment (including firmware, micro-code, etc.) or an embodiment combining hardware and software aspects may be referred to herein as a "circuit," module "or" system.
An electronic device according to this embodiment of the invention. The electronic device is merely an example, and should not impose any limitations on the functionality and scope of use of embodiments of the present invention.
The electronic device is in the form of a general purpose computing device. Components of an electronic device may include, but are not limited to: the at least one processor, the at least one memory, and a bus connecting the various system components, including the memory and the processor.
Wherein the memory stores program code that is executable by the processor to cause the processor to perform steps according to various exemplary embodiments of the present invention described in the above section of the exemplary method of this specification.
The storage may include readable media in the form of volatile storage, such as Random Access Memory (RAM) and/or cache memory, and may further include Read Only Memory (ROM).
The storage may also include a program/utility having a set (at least one) of program modules including, but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of which may include an implementation of a network environment.
The bus may be one or more of several types of bus structures including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or a local bus using any of a variety of bus architectures.
The electronic device may also communicate with one or more external devices (e.g., keyboard, pointing device, bluetooth device, etc.), with one or more devices that enable a user to interact with the electronic device, and/or with any device (e.g., router, modem, etc.) that enables the electronic device to communicate with one or more other computing devices. Such communication may be through an input/output (I/O) interface. And, the electronic device may also communicate with one or more networks such as a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network, such as the Internet, through a network adapter. The network adapter communicates with other modules of the electronic device via a bus. It should be appreciated that although not shown, other hardware and/or software modules may be used in connection with an electronic device, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, data backup storage systems, and the like.
From the above description of embodiments, those skilled in the art will readily appreciate that the example embodiments described herein may be implemented in software, or may be implemented in software in combination with the necessary hardware. Thus, the technical solution according to the embodiments of the present disclosure may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (may be a CD-ROM, a U-disk, a mobile hard disk, etc.) or on a network, including several instructions to cause a computing device (may be a personal computer, a server, a terminal device, or a network device, etc.) to perform the method according to the embodiments of the present disclosure.
In an exemplary embodiment of the present disclosure, a computer-readable storage medium having stored thereon a program product capable of implementing the method described above in the present specification is also provided. In some possible embodiments, the aspects of the invention may also be implemented in the form of a program product comprising program code for causing a terminal device to carry out the steps according to the various exemplary embodiments of the invention as described in the "exemplary method" section of this specification, when the program product is run on the terminal device.
The program product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium would include the following: an electrical connection having one or more wires, a portable disk, a hard disk, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
The computer readable signal medium may include a data signal propagated in baseband or as part of a carrier wave with readable program code embodied therein. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A readable signal medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.
Program code embodied on a readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Program code for carrying out operations of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of remote computing devices, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet service provider).
Furthermore, the above-described drawings are only schematic illustrations of processes included in the method according to the exemplary embodiment of the present invention, and are not intended to be limiting. It will be readily appreciated that the processes shown in the above figures do not indicate or limit the temporal order of these processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, for example, among a plurality of modules.
It should be noted that although in the above detailed description several modules or units of a device for action execution are mentioned, such a division is not mandatory. Indeed, the features and functionality of two or more modules or units described above may be embodied in one module or unit in accordance with embodiments of the present disclosure. Conversely, the features and functions of one module or unit described above may be further divided into a plurality of modules or units to be embodied.
The present invention is not limited to the above embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (10)
1. The calibration method of the five-axis interference measurement system is characterized in that the five-axis interference measurement system comprises an X translational shaft, a Y translational shaft, a Z translational shaft, a first rotating shaft, a second rotating shaft and an interference imaging measuring head, wherein the X translational shaft, the Y translational shaft and the Z translational shaft are connected with each other to form a three-dimensional moving platform; the first rotating shaft is fixedly connected to the Y translational shaft; the second rotating shaft is fixedly connected to the Z translational shaft; the interference imaging measuring head is fixedly connected to the second rotating shaft;
The measuring optical axis of the interference imaging measuring head is perpendicular to the central axis of the second rotating shaft; the first rotating shaft is used for clamping a workpiece to be tested; the central axis of the first rotating shaft is perpendicular to the central axis of the second rotating shaft;
the calibration method comprises the following steps:
Controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so as to enable the five-axis interference measurement system to be in an initial calibration posture; the initial calibration posture is a posture that the central axis of the first rotating shaft and the measuring optical axis of the interference imaging measuring head are in a collinear state in the Y-axis direction;
clamping a first calibration auxiliary workpiece on the first rotating shaft, and adjusting the installation position to enable the five-axis interference measurement system to be in a target calibration posture; the target calibration posture is a posture that the rotation axis of the first calibration auxiliary workpiece, the central axis of the first rotating shaft and the measurement optical axis of the interference imaging measuring head are all in a collinear state in the Y-axis direction; the first calibration auxiliary workpiece is a symmetrical revolving body; the surface to be measured of the first calibration auxiliary workpiece is an aspheric surface with a known surface type relationship, and the surface type of the surface to be measured meets the following conditions:
zw＝f(c,k,xw)
c and k are curvature values and cone coefficients corresponding to the surface to be measured respectively;
acquiring an inverse kinematics equation set of the five-axis interference measurement system under the target calibration posture; the system of inverse kinematics equations satisfies the following relationship:
Wherein X w,yw,zw is the distance between a certain point on the surface to be measured and the origin of the workpiece in the directions of X axis, Y axis and Z axis; the origin of the workpiece is the intersection point of the surface to be measured and the central axis of the first rotating shaft; x, Y and Z are distances between a certain point on the surface to be measured and the origin of the machine in the directions of the X axis, the Y axis and the Z axis respectively; the origin of the machine is the intersection point of the central axis of the second rotating shaft and the coplanar plane; the collinear plane is a plane parallel to the XZ plane and in which the central axis of the first rotation shaft is located; b is the rotation angle of the second rotation axis relative to the Z-axis direction; d is the distance between the origin of the machine and the focusing point of the interference imaging measuring head in the X-axis direction; l is the distance between the origin of the machine and the focusing point of the interference imaging measuring head in the Z-axis direction; l is the distance between the origin of the machine and the origin of the workpiece in the Z-axis direction;
acquiring position information of at least two points on the surface to be measured of the first calibration auxiliary workpiece, and taking the position information as calibration information;
And determining parameters d, L and L to be calibrated according to the calibration information, the inverse kinematics equation set and z w＝f(c,k,xw), and generating a kinematics model of the five-axis interference measurement system to complete the calibration work.
2. The method of claim 1, wherein the interferometric imaging probe has an image acquisition function;
Controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that the five-axis interference measurement system is in an initial calibration posture, comprising:
clamping a second calibration auxiliary workpiece onto the first rotating shaft, and adjusting the clamping position so that the rotation axis of the second calibration auxiliary workpiece and the central axis of the second rotating shaft are arranged in a collinear manner in the Y-axis direction; the second calibration auxiliary workpiece has a spherical surface;
And controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that the image of the spherical surface center point acquired by the interference imaging measuring head is positioned at the center of the field of view of the interference imaging measuring head.
3. The method of claim 2, wherein the spherical surface has at least one concentric circular tool mark thereon; the center of the concentric circle tool mark and the center of the spherical surface are both positioned on the central axis of the first rotating shaft;
Controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move so that an image of a spherical surface center point acquired by the interference imaging probe is positioned at the center of a field of view of the interference imaging probe, comprising:
And controlling at least one motion axis of the X translational axis, the Y translational axis, the Z translational axis, the first rotation axis and the second rotation axis to move according to the relative position of the concentric circle tool mark acquired by the interference imaging measuring head and the field of view center of the interference imaging measuring head, so that the image of the spherical surface center point acquired by the interference imaging measuring head is positioned at the field of view center of the interference imaging measuring head.
4. A method according to claim 3, wherein after controlling movement of at least one of the X translational axis, the Y translational axis, the Z translational axis, the first rotational axis, and the second rotational axis such that the image of the spherical surface center point acquired by the interferometric imaging probe is centered within the field of view of the interferometric imaging probe, the method further comprises:
controlling the Z translation axis to move, and acquiring interference fringe images shot by the interference imaging measuring head in real time;
and verifying the initial calibration posture according to the interference fringe image.
5. The method of claim 4, wherein verifying the initial calibration pose from the interference fringe image comprises:
if the annular interference fringes with alternate brightness exist in the interference fringe image, and the center of the annular interference fringes coincides with the center point of the spherical surface, verification is passed.
6. The method of claim 4, wherein if there are annular interference fringes with alternating light and dark in the interference fringe image, and the center of the annular interference fringes does not coincide with the center point of the spherical surface, the verification fails and a readjustment is required to bring the five-axis interferometry system into an initial calibration attitude.
7. The method according to claim 1, wherein acquiring position information of at least two points on the surface to be measured of the first calibration assistance workpiece as calibration information comprises:
And acquiring the position information of four points on the surface to be measured of the first calibration auxiliary workpiece, and taking the position information as calibration information.
8. The method of claim 7, wherein the four points as calibration information are uniformly distributed on the surface to be measured on the same side of the first calibration auxiliary workpiece axis of rotation.
9. A non-transitory computer readable storage medium storing a computer program, characterized in that the computer program, when executed by a processor, implements a method of calibrating a five-axis interferometry system according to any of claims 1-8.
10. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements a calibration method of a five-axis interferometry system according to any of claims 1-8 when the computer program is executed by the processor.
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