CN111272103B - Method for measuring spherical center and curvature radius of large-caliber spherical optical element - Google Patents
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Abstract
The invention discloses a method for measuring the sphere center and the curvature radius of a large-caliber spherical optical element. During measurement, the four laser displacement sensors simultaneously provide relative distances of four sampling points on the spherical optical element; the data acquisition unit and the analysis processing unit automatically calculate a spherical coordinate equation through relative distance, and output the position of the center of the sphere and the curvature radius. In the measuring process, the sampling positions can be replaced through the movement of the three-dimensional displacement table, the measurement is carried out at a plurality of sampling positions, the results are averaged, and the measurement precision is improved. The method has simple operation steps, does not need any movement of the large-caliber spherical optical element, effectively reduces the complexity and the cost of a mechanical structure, and realizes the non-contact and rapid measurement of the spherical center and the curvature radius of the large-caliber spherical optical element.
Description
Technical Field
The invention belongs to the technical field of optics, and particularly relates to a method for measuring the sphere center and the curvature radius of a large-caliber spherical optical element.
Background
In order to obtain high-energy laser output in a large-sized laser driving device, it is necessary to manufacture an optical element having a large diameter and a high laser damage threshold. The processing quality of these optical elements has a particularly important influence on the laser damage threshold, and in particular, surface defects such as pits and scratches are critical factors affecting the laser damage threshold. At present, a microscopic imaging system is mainly adopted to scan and image the surface of a detected sample, so that the appearance and distribution of surface defects are obtained. As an important means for achieving beam focusing, a large-diameter spherical optical element is an indispensable part of a laser driving device. Nowadays, a large-caliber spherical optical element is generally designed to be a hemispherical structure with a spherical front surface and a rectangular plane rear surface, and the length and width dimensions of the spherical optical element are developed to hundreds to thousands of millimeters, and the weight of the spherical optical element is hundreds of kilograms. Because the detected surface of the large-caliber spherical optical element is a spherical surface and the imaging surface of the microscopic imaging system is a plane with a smaller size, the spherical surface has different projection proportions on the imaging surface when scanning imaging is carried out at different positions of the spherical surface. Only by obtaining the curvature center position (namely the sphere center) and the curvature radius of the detected spherical surface, the mapping relation between the detected spherical surface and the focal plane can be established, and finally, the high-precision detection of the surface defects of the large-caliber spherical optical element is realized. Therefore, when the large-caliber spherical optical element is detected, the measurement of the center and the curvature radius is an indispensable important process.
The existing spherical optical element curvature radius measuring methods are numerous, for example, chinese patent publication No. CN105737763A discloses a spherical mirror curvature radius measuring method based on moire fringes, chinese patent publication No. CN106908016A discloses a concave mirror curvature radius measuring method based on a light field camera, and chinese patent publication No. CN106595529A discloses a large curvature radius non-zero interference measuring method and device based on virtual newton rings. The methods adopt a non-contact method to measure the curvature radius of the spherical surface, can detect that the caliber of the spherical surface is small, and cannot simultaneously obtain the position coordinate of the center of the spherical surface.
For example, chinese patent publication No. CN105157617A discloses an automatic spherical centering method applied to surface defect detection of a spherical optical element, which uses spherical reflection cross-hair imaging, and uses a self-rotating table to drive a spherical optical element to be detected to rotate, observe the position change of the cross-hair, and fit the center of a circle of a cross-hair motion trajectory, thereby realizing spherical optical element centering and curvature radius measurement. However, this method has high requirements on mechanical structure, and it is necessary to design a self-rotating stage structure to rotate the sample, which increases the complexity of design, processing and adjustment. For large-aperture spherical optical elements with long and wide dimensions of hundreds to thousands of millimeters and weights of hundreds of kilograms, it is obvious that designing the structure of the self-rotating platform will greatly increase the mechanical complexity of the system and increase the time required for measurement. Therefore, the method is not suitable for measuring the center and the curvature radius of the large-caliber spherical optical element.
Therefore, it is necessary to design a device and a method with simple structure and high measurement efficiency to realize the measurement of the spherical center and the curvature radius of the large-caliber spherical optical element.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for measuring the spherical center and the curvature radius of a large-caliber spherical optical element, which realizes the non-contact and rapid measurement of the spherical center and the curvature radius of the large-caliber spherical optical element.
The technical scheme of the invention is as follows:
a method for measuring the sphere center and the curvature radius of a large-caliber spherical optical element adopts an automatic measuring device, wherein the automatic measuring device comprises a sample table, a three-dimensional displacement table, four laser displacement sensors arranged on the three-dimensional displacement table, a data acquisition unit electrically connected with the laser displacement sensors, a data analysis processing unit electrically connected with the data acquisition unit, and a control unit used for receiving the calculation result of the data analysis processing unit and moving the three-dimensional displacement table;
the method specifically comprises the following steps:
(1) calibrating the initial positions of the four laser displacement sensors; (ii) a
(2) Fixing the large-caliber spherical optical element on a sample table through a clamping mechanism by adopting a vertical placing posture;
(3) moving X, Y two shafts of the three-dimensional displacement table to enable four sampling points of the four laser displacement sensors to be located on the surface of the spherical optical element; wherein, the X, Y axis of the three-dimensional displacement table is perpendicular to the optical axis of the spherical optical element;
(4) moving the Z axis of the three-dimensional displacement table to enable all the four laser displacement sensors to be located within the working distance, and obtaining the relative distance between the four sampling points on the large-caliber spherical optical element and the laser displacement sensors; the Z axis of the three-dimensional displacement table is parallel to the optical axis of the spherical optical element, and the origin 0 is located at the mechanical starting point of the XYZ axis of the three-dimensional displacement table;
(5) the data acquisition unit receives the relative distances d between the four sampling points and the corresponding four laser displacement sensors in real time1、d2、d3、d4And current XY-axis coordinate (X) of the three-dimensional displacement table0，Y0) The data analysis processing unit calculates the coordinates (x) of the center of the spherec，yc，zc) And a radius of curvature r;
(6) moving X, Y two axes of the three-dimensional displacement platform to other sampling positions, repeating the step (5) and obtaining a plurality of groups of spherical center coordinates and curvature radius solutions; and averaging the multiple groups of data to finish the measurement of the spherical center and the curvature radius of the large-caliber spherical optical element.
In the automatic measuring device, the measuring directions of the four laser displacement sensors are parallel to the Z axis, and the relative distances from four sampling points on the spherical optical element to the laser displacement sensors are provided. The data acquisition unit is connected with four laser displacement sensors, receives the relative distance of four sampling points in real time, transmits the relative distance to the data analysis processing unit, and calculates the sphere center position and the curvature radius of the spherical optical element. In the measuring process, the sampling positions can be replaced through the movement of the three-dimensional displacement table, the measurement is carried out at a plurality of sampling positions, the results are averaged, and the measurement precision is improved.
The four laser displacement sensors are arranged on the three-dimensional displacement table in a rectangular shape, and the side length of the rectangle is parallel to or perpendicular to the X, Y axis; and the measuring directions of the four laser displacement sensors are all parallel to the Z axis.
The laser displacement sensor is a non-contact measuring sensor, and the linear distance between an object to be measured and the sensor is obtained by applying the laser triangular reflection principle.
The measuring direction of the laser displacement sensor is the emergent laser direction of the laser displacement sensor, namely the direction of the linear distance between the object to be measured and the sensor.
The large-caliber spherical optical element is fixed on the sample stage through a clamping mechanism.
The specific process of the step (1) is as follows:
(1-1) adopting a vertical placing posture, and fixing the large-caliber spherical optical element for calibration on the sample table through a clamping mechanism.
(1-2) moving X, Y two axes of the three-dimensional displacement platform to enable the sampling point of the first laser displacement sensor to be positioned on the surface of the spherical optical element.
And (1-3) moving the Z axis of the three-dimensional displacement table to enable the first laser displacement sensor to be located within the working distance, and obtaining the relative distance between the sampling point on the large-caliber spherical optical element and the laser displacement sensor.
(1-4) using a three-dimensional displacement platform to bear a first laser displacement sensor, scanning two section lines of the large-caliber spherical optical element along the direction X, Y, and recording the coordinate position of the three-dimensional displacement platform and the relative distance d acquired by the first laser displacement sensor in real time1(ii) a In the X direction, d1When the minimum value is obtained, the corresponding X-axis coordinate of the three-dimensional displacement table is recorded as X1(ii) a In the Y direction, d1When the minimum value is obtained, the Y-axis coordinate of the corresponding three-dimensional displacement table is recorded as Y1；(X1，Y1) The calibration position of the first laser displacement sensor is obtained.
(1-5) repeating the method from the step (1-2) to the step (1-4) to obtain the calibration position (X) of the second laser displacement sensor2，Y2) And the calibration position (X) of the third laser displacement sensor3，Y3) And the calibration position (X) of the fourth laser displacement sensor4，Y4)。
(1-6) moving the three-dimensional displacement stage to the coordinate position ((X)1+X2)/2，(Y1+Y3) And/2), at the moment, the central points of the four laser displacement sensors are superposed with the axis line of the large-caliber spherical optical element.
Since the surface of the spherical optical element is a spherical surface and the vertex of the spherical surface is closest to the laser displacement sensor, when the XY axes of the three-dimensional displacement table are sequentially moved to the coordinate position (X)1，Y1)、(X2，Y2)、(X3，Y3)、(X4，Y4) The four sampling points are sequentially connected with the spherical surfaceThe vertexes are coincided, namely the four laser displacement sensors are respectively coincided with the axial lead of the spherical optical element. Therefore, when the three-dimensional displacement table moves to the coordinate position ((X)1+X2)/2，(Y1+Y3) And/2), the central points of the four laser displacement sensors are superposed with the axis line of the large-caliber spherical optical element.
(1-7) the section formed by the four sampling points is just a rectangular section vertical to the axis, and the center of the rectangle is the position of the axis of the large-caliber spherical optical element. At the moment, the relative distances d acquired by the four laser displacement sensors1、d2、d3、d4And setting the initial position of the four laser displacement sensors to be 0, and finishing the calibration of the initial positions of the four laser displacement sensors.
The purpose of calibrating the initial positions of the four laser displacement sensors is as follows: when the system is installed, the four laser displacement sensors cannot be strictly ensured to be positioned in the same plane; therefore, the initial relative distances of the four laser displacement sensors need to be calibrated before measurement, and the relative position information of the four laser displacement sensors is obtained. If the relative positions of the four laser displacement sensors are not changed, calibration work is only needed to be carried out when the system is used for the first time.
In the step (2), the vertical placement posture is that the optical axis of the spherical optical element is placed in parallel with the horizontal plane.
In step (5), the coordinates of the center of sphere (x)c，yc，zc) And the radius of curvature r is calculated as follows:
the XYZ axes of the three-dimensional displacement table are taken as reference coordinate axes, and the origin 0 is located at the mechanical starting point of the XYZ axes of the three-dimensional displacement table; a spherical sampling point corresponding to the first laser displacement sensor is marked as M and is positioned at the upper right; a spherical sampling point corresponding to the second laser displacement sensor is marked as N and is positioned at the lower right; a spherical sampling point corresponding to the third laser displacement sensor is marked as P and is positioned at the lower left; a spherical sampling point corresponding to the fourth laser displacement sensor is marked as Q, and the displacement is left-upper; the coordinates are respectively noted as (x)M，yM，zM)、(xN，yN，zN)、(xP，yP，zP)、(xQ，yQ，zQ) (ii) a The coordinates of the center of the sphere are (x)c，yc，zc) The curvature radius is recorded as r;
according to the initial position calibration result and the current three-dimensional displacement table coordinate (X)0，Y0) Obtaining:
and zM＝d1、zN＝d2、zP＝d3、zQ＝d4By the following formula:
simultaneous and resolution of xc，yc，zcAnd r.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a new device and a new method for measuring the sphere center and the curvature radius of the large-caliber spherical optical element, and for the large-caliber spherical optical element, only the laser displacement sensor needs to be carried for three-dimensional movement, and a sample spinning platform structure is not needed, so that the mechanical design and the assembly and adjustment difficulty are greatly reduced; four laser displacement sensors are adopted to sample on the spherical surface in real time, so that multiple groups of sampling data can be obtained, and the speed and the precision of measuring the spherical center and the curvature radius are greatly improved. The measuring device is simple, is convenient to operate, has high application value, and lays a foundation for the surface defect detection of the large-caliber spherical optical element with high speed, high precision and non-contact.
Drawings
FIG. 1 is a schematic view of an automatic measuring device according to the present invention;
FIG. 2 is a schematic diagram of the calibration of the initial position of the laser displacement sensor according to the present invention;
FIG. 3 is a calibration curve diagram of the initial displacement of the laser displacement sensor according to the present invention;
FIG. 4 is a diagram showing the relationship between the coordinates of the three-dimensional displacement table and the coordinates of the spherical center of the spherical optical element according to the present invention.
FIG. 5 is a flow chart of the method for measuring the spherical center and the curvature radius of the large-caliber spherical optical element according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, in which the following embodiments are provided to facilitate understanding of the present invention and are not intended to limit the present invention in any way.
The method adopts an automatic measuring device, as shown in figure 1, a large-caliber spherical optical element 9 to be measured is fixed on a sample table by adopting a vertical placing posture, and four laser displacement sensors respectively comprise: the displacement sensor comprises a first laser displacement sensor 1, a second laser displacement sensor 2, a third laser displacement sensor 3 and a fourth laser displacement sensor 4. The four laser displacement sensors are fixed on the three-dimensional displacement table, and the X, Y axis of the three-dimensional displacement table is perpendicular to the optical axis of the spherical optical element 9, so that the laser displacement sensors can be borne to perform two-dimensional translation; the Z axis is parallel to the optical axis of the spherical optical element 9, and can bear the axial translation of the laser displacement sensor. The origin 0 is located at the mechanical starting point of the XYZ axes of the three-dimensional displacement table.
The four laser displacement sensors are arranged in a plane XY, connecting lines of the arrangement positions of the four laser displacement sensors form a rectangle, wherein the connecting line of the arrangement positions of the first laser displacement sensor 1 and the second laser displacement sensor 2 is parallel to a Y axis, and the connecting line of the arrangement positions of the second laser displacement sensor 2 and the third laser displacement sensor 3 is parallel to an X axis. And calibrating the initial positions of the four laser displacement sensors to obtain the accurate position coordinates of the four laser displacement sensors. The measuring direction of the laser displacement sensor is parallel to the Z axis, and the relative distance between four sampling points on the spherical optical element and the laser displacement sensor is provided. Wherein the first laser displacement sensor 1 corresponds to sampling point 5, the second laser displacement sensor 2 corresponds to sampling point 6, the third laser displacement sensor 3 corresponds to sampling point 7, and the fourth laser displacement sensor 4 corresponds to sampling point 8.
The data acquisition unit is connected with the four laser displacement sensors, receives the relative distances of the four sampling points in real time, transmits the relative distances to the data analysis processing unit, and calculates the sphere center position and the curvature radius of the spherical optical element 9. In the measuring process, the sampling positions can be replaced through the movement of the three-dimensional displacement table, the measurement is carried out at a plurality of sampling positions, the results are averaged, and the measurement precision is improved.
Referring to fig. 2, the calibration method for the initial positions of four laser displacement sensors is as follows:
and 5, repeating the method in the step 4 to obtain the calibration position (X) of the second laser displacement sensor 22，Y2) The calibration position (X) of the third laser displacement sensor 33，Y3) The calibration position (X) of the fourth laser displacement sensor 44，X4)；
The method for measuring the spherical center and the curvature radius of the large-caliber spherical optical element 9 comprises the following steps:
s01, fixing the large-caliber spherical optical element 9 on a sample table through a clamping mechanism by adopting a vertical placement posture;
s02, moving two shafts X, Y of the three-dimensional displacement table to enable four sampling points of the four laser displacement sensors to be located on the surface of the spherical optical element 9;
s03, moving the Z axis of the three-dimensional displacement table to enable all the four laser displacement sensors to be located within the working distance, and obtaining the relative distance between the four sampling points on the large-caliber spherical optical element 9 and the laser displacement sensors;
s04, as shown in figure 4, the data acquisition unit receives the relative distance d of the four sampling points in real time1、d2、d3、d4And the current XY-axis coordinate 10 of the three-dimensional displacement table is (X)0，Y0) The coordinates (x) of the center 11 of the sphere are calculated by a data analysis processing unitc，yc，zc) And a radius of curvature r; the specific treatment method comprises the following steps:
the XYZ axes of the three-dimensional displacement table are taken as reference coordinate axes, and the origin 0 is positioned at the mechanical starting point of the XYZ axes of the three-dimensional displacement table. A spherical sampling point corresponding to the first laser displacement sensor 1 is marked as M and is positioned at the upper right; a spherical sampling point corresponding to the second laser displacement sensor 2 is marked as N and is positioned at the lower right; a spherical sampling point corresponding to the third laser displacement sensor 3 is marked as P and is positioned at the lower left; a spherical sampling point corresponding to the fourth laser displacement sensor 4 is marked as Q, and the displacement is left-upper; the coordinates are respectively noted as (x)M，yM，zM)、(xN，yN，zN)、(xP，yP，zP)、(xQ，yQ，zQ). The coordinates of the center of the sphere are (x)c，yc，zc) The radius of curvature is denoted as r.
According to the initial position calibration result and the current three-dimensional displacement table coordinate (X)0，Y0) Obtaining:
and zM＝d1、zN＝d2、zP＝d3、zQ＝d4This may be achieved by the following formula:
simultaneous and resolution of xc，yc，zcAnd r.
S05, moving the XY two axes of the three-dimensional displacement table to other sampling positions, repeating the step 4 and obtaining a plurality of groups of spherical center coordinates (x)c，yc，zc) And radius of curvature solution r; and averaging multiple groups of data to finish the measurement of the spherical center and the curvature radius of the large-caliber spherical optical element 9.
In order to verify the effect of the method of the present invention, the present embodiment uses a large-caliber spherical optical element to perform simulation measurement on the method described in the present invention. The large-caliber spherical optical element is a plano-convex optical element with the length of 800mm, the width of 600mm and the curvature radius of 2000 mm. The actual sphere center coordinates are (457, 343, 2082) with respect to the XYZ origin of coordinates; the used laser displacement sensors are four laser displacement sensors with the same type, the working distance is 90 +/-20 mm, and the linear precision is +/-12 mu m; the three-dimensional displacement table is a large-stroke high-precision three-dimensional displacement table, and the positioning precision of the three-dimensional displacement table is +/-10 mu m. The four laser displacement sensors are arranged on the three-dimensional displacement platform, the distance between the four laser displacement sensors and a sample is about 80mm, and the connecting lines of the arrangement positions of the four laser displacement sensors form a square with the side length of 300 mm.
Firstly, the initial positions of four laser displacement sensors are calibrated by using the laser displacement sensor calibration method, and the obtained results are shown in table 1.
TABLE 1
The device and the method for measuring the spherical center and the curvature radius of the large-caliber spherical optical element are used for centering. In step S03, the relative distances from the laser displacement sensor to the four sampling points on the spherical optical element are obtained as shown in table 2.
TABLE 2
Using the data analysis method described in step S04, the sphere center coordinates (456.3633, 342.5152, 2059.67), radius 1977.79, can be solved from the relative distances of the four laser displacement sensors, and the initial calibration results. The sampling positions were changed using a three-dimensional displacement table, and the coordinates and radii of the spherical centers obtained were as shown in table 3.
TABLE 3
| Number of samplings | X coordinate of sphere center | Y coordinate of sphere center | Z coordinate of sphere center | Radius of |
| 1 | 456.36 | 342.52 | 2059.67 | 1977.79 |
| 2 | 454.55 | 341.09 | 1993.99 | 1912.48 |
| 3 | 459.58 | 344.90 | 2170.74 | 2088.31 |
| 4 | 465.57 | 349.41 | 2380.96 | 2297.79 |
| Mean value of | 459.02 | 344.48 | 2151.34 | 2069.09 |
| Relative error | 0.44％ | 0.43％ | 3.33％ | 3.45％ |
In this embodiment, the XYZ coordinate relative errors of the sphere center obtained by the automatic measuring apparatus and method of the present invention are 0.44%, 0.43%, and 3.33%, and the radial relative error is 3.45%. Relative errors mainly come from three-dimensional displacement table positioning errors and laser displacement sensor measurement errors, and the centering precision can be greatly improved by selecting a three-dimensional displacement table and a laser displacement sensor with higher precision. Therefore, the method can realize high-precision measurement of the spherical center and the curvature radius of the large-caliber spherical optical element.
The above description is only exemplary of the preferred embodiments of the present invention, and is not intended to limit the present invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A method for measuring the sphere center and the curvature radius of a large-caliber spherical optical element is characterized in that an automatic measuring device is adopted, and the automatic measuring device comprises a sample table, a three-dimensional displacement table, four laser displacement sensors arranged on the three-dimensional displacement table, a data acquisition unit electrically connected with the laser displacement sensors, a data analysis processing unit electrically connected with the data acquisition unit, and a control unit used for receiving the calculation result of the data analysis processing unit and moving the three-dimensional displacement table;
the method specifically comprises the following steps:
(1) calibrating the initial positions of the four laser displacement sensors;
(2) fixing the large-caliber spherical optical element on a sample table through a clamping mechanism by adopting a vertical placing posture;
(3) moving X, Y two shafts of the three-dimensional displacement table to enable four sampling points of the four laser displacement sensors to be located on the surface of the spherical optical element; wherein, the X, Y axis of the three-dimensional displacement table is perpendicular to the optical axis of the spherical optical element;
(4) moving the Z axis of the three-dimensional displacement table to enable all the four laser displacement sensors to be located within the working distance, and obtaining the relative distance between the four sampling points on the large-caliber spherical optical element and the laser displacement sensors; the Z axis of the three-dimensional displacement table is parallel to the optical axis of the spherical optical element;
(5) the data acquisition unit receives the relative distances d between the four sampling points and the corresponding four laser displacement sensors in real time1、d2、d3、d4And current XY-axis coordinate (X) of the three-dimensional displacement table0,Y0) The data analysis processing unit calculates the coordinates (x) of the center of the spherec,yc,zc) And a radius of curvature r;
(6) moving X, Y two axes of the three-dimensional displacement platform to other sampling positions, repeating the step (5) and obtaining a plurality of groups of spherical center coordinates and curvature radius solutions; and respectively solving and averaging the coordinates of the spherical centers and the curvature radii of the groups to finish the measurement of the coordinates of the spherical centers and the curvature radii of the large-caliber spherical optical elements.
2. The method for measuring the spherical center and the curvature radius of the large-caliber spherical optical element according to claim 1, wherein the four laser displacement sensors are arranged on the three-dimensional displacement table in a rectangular shape, and the side length of the rectangle is parallel to or perpendicular to the X, Y axis; and the measuring directions of the four laser displacement sensors are all parallel to the Z axis.
3. The method for measuring the spherical center and the curvature radius of the large-caliber spherical optical element according to claim 1, wherein the specific process of the step (1) is as follows:
(1-1) fixing a large-caliber spherical optical element for calibration on a sample table through a clamping mechanism by adopting a vertical placing posture;
(1-2) moving X, Y two shafts of the three-dimensional displacement platform to enable a sampling point of the first laser displacement sensor to be located on the surface of the spherical optical element;
(1-3) moving the Z axis of the three-dimensional displacement table to enable the first laser displacement sensor to be located within the working distance, and obtaining the relative distance between the sampling point on the large-caliber spherical optical element and the laser displacement sensor;
(1-4) using a three-dimensional displacement platform to bear a first laser displacement sensor to scan the large-caliber spherical surfaceTwo section lines of the optical element along the direction X, Y record the coordinate position of the three-dimensional displacement table and the relative distance d acquired by the first laser displacement sensor in real time1(ii) a In the X direction, d1When the minimum value is obtained, the corresponding X-axis coordinate of the three-dimensional displacement table is recorded as X1(ii) a In the Y direction, d1When the minimum value is obtained, the Y-axis coordinate of the corresponding three-dimensional displacement table is recorded as Y1；(X1,Y1) The calibration position of the first laser displacement sensor is obtained;
(1-5) repeating the method from the step (1-2) to the step (1-4) to obtain the calibration position (X) of the second laser displacement sensor2,Y2) And the calibration position (X) of the third laser displacement sensor3,Y3) And the calibration position (X) of the fourth laser displacement sensor4,Y4)；
(1-6) moving the three-dimensional displacement stage to the coordinate position ((X)1+X2)/2,(Y1+Y3) 2), the central points of the four laser displacement sensors coincide with the axis of the large-caliber spherical optical element;
(1-7) relative distance d acquired by four laser displacement sensors1、d2、d3、d4And setting the initial position of the four laser displacement sensors to be 0, and finishing the calibration of the initial positions of the four laser displacement sensors.
4. The method for measuring the spherical center and the radius of curvature of a large-caliber spherical optical element according to claim 1, wherein in the step (2), the spherical optical element is vertically placed in a state that the optical axis of the spherical optical element is parallel to the horizontal plane.
5. The method for measuring the spherical center and the curvature radius of a spherical optical element with a large aperture according to claim 1, wherein in the step (5), the coordinates (x) of the spherical center are determinedc,yc,zc) And the radius of curvature r is calculated as follows:
the XYZ axes of the three-dimensional displacement table are taken as reference coordinate axes, and the origin 0 is located at the mechanical starting point of the XYZ axes of the three-dimensional displacement table; a spherical sampling point corresponding to the first laser displacement sensor is marked as M and is positioned at the upper right; second laser positionA spherical sampling point corresponding to the motion sensor is marked as N and is positioned at the lower right; a spherical sampling point corresponding to the third laser displacement sensor is marked as P and is positioned at the lower left; a spherical sampling point corresponding to the fourth laser displacement sensor is marked as Q, and the displacement is left-upper; the coordinates are respectively noted as (x)M,yM,zM)、(xN,yN,zN)、(xP,yP,zP)、(xQ,yQ,zQ) (ii) a The coordinates of the center of the sphere are (x)c,yc,zc) The curvature radius is recorded as r;
according to the initial position calibration result and the current three-dimensional displacement table coordinate (X)0,Y0) Obtaining:
and zM＝d1、zN＝d2、zP＝d3、zQ＝d4By the following formula:
simultaneous and resolution of xc,yc,zcAnd r.
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