Method for centering circular plane lens

Abstract

The invention relates to the field of precision measurement, in particular to a circular plane lens centering method, which comprises the following steps of: establishing a coordinate calculation template through a geometric algorithm, and recording an angle alpha, an angle beta and a side length L of an auxiliary device; measuring the radius of the lens and recording a measured value; the lens is placed in a V-shaped frame of the auxiliary device, so that the outer diameter of the lens is tangent to two side rods of the V-shaped frame; fixing the lenses by using plasticine or soft red wax; placing the auxiliary device on which the lens is fixed on an objective table of measuring equipment; two-dimensional geometric position center point coordinates of the standard ball A and the standard ball B are measured respectively, the coordinate X value and the coordinate Y value of the standard ball A and the standard ball B are recorded, and the coordinate position of the vertex C of the point V-shaped frame is solved synchronously; and inputting the coordinate values of the standard ball A and the standard ball B into the calculation template to obtain the coordinate X value and the coordinate Y value of the center of the lens. The method can be used for defining the center point of the lens by contact type measuring equipment only provided with an upper surface probe.

Description

Technical Field

[0001] The invention relates to the field of precision measurement, and in particular to a method for centering a circular plane lens. Background Art

[0002] With the continuous iterative development of the optical field, its application scope is becoming more and more extensive. It is necessary to design lenses of different shapes for combination (such as: plane and aspheric surface, plane and spherical surface, spherical surface and aspheric surface, etc.) to meet the needs of different usage scenarios. The surface shape accuracy of the lens often requires high-precision measuring equipment to check whether it meets the design requirements. Among high-precision surface detection equipment, it is generally divided into contact and non-contact types (the following is an explanation of contact equipment).

[0003] In the process of measuring the lens surface shape with a contact device (taking Panasonic-UA3P as an example), centering (which can be understood as defining the origin or starting point) is a key link in the measurement process. It often relies on the upper surface probe of the device to define the physical highest / lowest point of the product to be tested, or fits and defines the center based on relevant design parameters.

[0004] However, no matter which measurement method is selected, the center position must be defined first. Note: The above centering is not the absolute center position (which does not actually exist), but the center position is controlled within the set error range. (For example: the error range is set to 2um, when the deviation between the actual center and the theoretical center is ≤2um, then the centering is considered to be completed.) Therefore, when the lens is changed to a flat surface or a near-flat surface (for example, a spherical or aspherical surface with a curvature radius R of 20,000 mm), its center cannot be accurately defined according to the existing method, resulting in the inability to correctly select the measurement path, which leads to measurement failure or data distortion. Then the method of centering the circular flat surface (near-flat surface) lens will become crucial. Summary of the invention

[0005] The object of the present invention is to provide a method for centering a circular plane lens, which method can be used for defining the center point of the lens using a contact type measuring device having only an upper surface probe.

[0006] The technical solution of the present invention is: a method for centering a circular plane lens, comprising an auxiliary device, the auxiliary device comprising a supporting base plate, a V-shaped frame is fixed on the upper surface of the supporting base plate, and standard balls A and B are correspondingly arranged at the ends of the two side rods of the V-shaped frame, and the method steps are as follows: 1) Establish a coordinate calculation template through geometric algorithm, and record the auxiliary device angle α, angle β and side length L, where angle β is the angle of the V-frame and angle α is half of the angle of the V-frame; 2) Measure the radius of the lens and record the measurement; 3) Place the lens into the V-shaped frame of the auxiliary device so that the outer diameter of the lens is tangent to the two side rods of the V-shaped frame; 4) Use plasticine or soft red wax to fix the lens; 5) Place the auxiliary device with the lens fixed on the stage of the measuring equipment; 6) Measure the coordinates of the two-dimensional geometric center points of the standard sphere A and the standard sphere B respectively, and record the X and Y values ​​of the coordinates of the standard sphere A and the standard sphere B, and simultaneously calculate the coordinate position of the vertex C of the V-shaped frame; 7) Input the coordinate values ​​of standard sphere A and standard sphere B into the calculation template to obtain the X and Y coordinate values ​​of the center of the lens; 8) Enter the calculated coordinate value on the measuring device, move the probe to the coordinate, define it as the origin, and after focusing, measure along the set path.

[0007] Furthermore, both side rod ends of the V-shaped frame are provided with mounting parts, and the standard ball A and the standard ball B are installed in the corresponding mounting parts.

[0008] Furthermore, countersunk holes are provided on the bottom surface of the supporting base plate and on the lower side of the mounting portion, and top pieces for supporting the standard balls A and B are installed in the countersunk holes.

[0009] Furthermore, the V-shaped frame is replaced by an isosceles triangle frame, and the supporting base plate is provided with a hollow portion.

[0010] Furthermore, the angle β is 60° and the angle α is 30°.

[0011] Furthermore, the analytical process of the calculation equation of the lens center coordinates is as follows: 1) Assume that the coordinates of the standard sphere A are (X1, Y1), and the coordinates of the standard sphere B are (X2, Y2); the coordinates of the vertex C of the V-shaped frame are (X3, Y3); point C, the standard spheres A and B form an equilateral triangle, any angle of which is represented by ∠β, and any side length is represented by AC, then AC=BC=AB; 2) Since the lens is tangent to both sides of the V-frame, assume that the tangent point intersects AC at point P2 and BC at point P3. The radius of the lens is represented by r, the center of the lens is Q, and CQ, AQ, and BQ are connected. Then CQ is the angle bisector of ∠β, and AQ=BQ. The coordinates of the lens center Q are (X, Y) and are calculated as follows: ① The angle θ between the line AB and the X-axis of the mechanical coordinate system of the testing equipment is: , the length L of AB is: ; because , then the coordinates of point C (X3, Y3) are: , ; ② Based on the known conditions, we can get: ,so ; Also because , set as formula (1), but ; ③ Due to , set as formula (2), Similarly: ; ④ Also because , set as formula (3), therefore, Formula (1) is transformed into: , set as formula (4); Formula (2) is transformed into: , set as formula (5); Formula (3) is transformed into: , set as formula (6); From formula (4)-formula (5), we can get: , set as formula (7); From formula (4) to formula (6), we can get: , set as formula (8); ⑤ Note: , Then formula (7) becomes , set as formula (9); , set as formula (10); From formula (9), we get: , set as formula (11); ⑥ Substituting formula (11) into formula (10), we get: , Right now , Right now , therefore, , find the Y value and then plug it into formula (11) to get the X value.

[0012] Compared with the prior art, the present invention has the following advantages: The basic principle of this method is based on the fixed triangular relationship between two standard balls (the center point of the ball is convenient for measurement by the upper surface probe) and the V-groove, combined with the actual radius of the lens, and through geometric algorithms, the center position of the lens is accurately calculated. A single upper surface probe device can achieve micron-level centering effect on special surfaces and shapes of circular lenses. Not only is the centering accuracy high (the auxiliary device is processed by ultra-precision equipment, the error is <1um, the lens roundness is generally <1um, the detection equipment error is <50nm, and the comprehensive centering accuracy is <3um), but it is also simple, convenient and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the existing upper surface probe; Figure 2 Examples of probes probing lens surfaces of different shapes; Figure 3 Examples of the center point locations of different types of lenses; Figure 4 A schematic diagram of path selection for measuring lens surface shape using existing contact devices; Figure 5 It is a schematic diagram of the structure of the auxiliary device of the present invention; Figure 6 is a cross-sectional view of the auxiliary device of the present invention; Figure 7 It is a schematic diagram of the lens of the present invention being placed on an auxiliary device and then fixed with red wax and placed into a measuring device; Figure 8 Schematic diagram of the standard sphere A, sphere B, point C and the tangent points of the lens and each edge of the present invention; Fig. 9 Schematic diagram of coordinates of ball A, ball B, and point C of the present invention; In the figure: 1-lens 2-plasticine or soft red wax 10-auxiliary device 11-supporting base plate 12-V-frame 13-standard ball A 14-standard ball B 15-installation part 16-counterbore 17-top piece. DETAILED DESCRIPTION

[0014] In order to make the above features and advantages of the present invention more easily understood, embodiments are given below with reference to the accompanying drawings for detailed description, but the present invention is not limited thereto.

[0015] refer to Figures 5 to 9 A method for centering a circular plane lens includes an auxiliary device 10, the auxiliary device includes a supporting base plate 11, a V-shaped frame 12 is fixed on the upper surface of the supporting base plate, and standard balls A13 and B14 are correspondingly arranged at the ends of the two side rods of the V-shaped frame. The method steps are as follows: 1) A coordinate calculation template is established through a geometric algorithm, and the auxiliary device angle α, angle β and side length L are recorded (constant, input only once), where angle β is the angle of the V-frame, and angle α is half of the angle of the V-frame; specifically, the angle β is 60° and the angle α is 30°.

[0016] 2) Measure the radius of the lens and record the measurement; 3) Place the lens 1 into the V-shaped frame of the auxiliary device so that the outer diameter of the lens is tangent to the two side rods of the V-shaped frame; 4) Use plasticine or soft red wax 2 to fix the lens; 5) Place the auxiliary device with the lens fixed on the stage of the measuring equipment in the following general directions Figure 7 .

[0017] 6) Measure the coordinates of the two-dimensional geometric center points of the standard sphere A and the standard sphere B respectively, and record the X and Y values ​​of the coordinates of the standard sphere A and the standard sphere B, and simultaneously calculate the coordinate position of the vertex C of the V-shaped frame.

[0018] 7) Input the coordinate values ​​of standard sphere A and standard sphere B into the calculation template to obtain the X and Y coordinate values ​​of the center of the lens; 8) Enter the calculated coordinate value on the measuring device, move the probe to the coordinate, define it as the origin, and after focusing, measure along the set path.

[0019] In this embodiment, both side rod ends of the V-shaped frame are provided with mounting portions 15, and the standard ball A and the standard ball B are mounted in the corresponding mounting portions.

[0020] In this embodiment, countersunk holes 16 are provided on the bottom surface of the supporting base plate and on the lower side of the mounting portion, and top pieces 17 for supporting the standard balls A and B are installed in the countersunk holes to fix the standard balls A and B, and the upper surfaces of the standard balls A and B are exposed to the mounting holes provided on the mounting portion.

[0021] In another embodiment, the V-shaped frame can be designed as an isosceles triangle frame according to actual needs, and the supporting bottom plate can be hollowed out according to the shape of the lens.

[0022] In this embodiment, the analytical process of the calculation equation of the lens center coordinates is as follows: Known: 1) Assume that the coordinates of the standard sphere A are (X1, Y1) and the coordinates of the standard sphere B are (X2, Y2) - obtained through step 6); The coordinates of the vertex C of the V-frame are (X3, Y3); point C, standard sphere A and standard sphere B form an equilateral triangle, any angle of which is represented by ∠β, and any side length is represented by AC, then AC=BC=AB; ∠β and side length AC are design values, which can be obtained by actual measurement with auxiliary devices; 2) Since the lens is tangent to both sides of the V-frame, assume that the tangent point intersects AC at point P2 and intersects BC at point P3. The radius of the lens is represented by r. The center of the lens is Q. Connect CQ, AQ, and BQ, then CQ is the angle bisector of ∠β, and AQ=BQ; - The radius r of the lens is obtained through step 2), ∠α=½∠β.

[0023] 3) The coordinate Q of the lens center is (X, Y) and is calculated as follows: ① Since sphere A, sphere B and point C form an equilateral triangle, sphere A (X1, Y1) and sphere B (X2, Y2) are known; Therefore, the angle θ between the line AB and the X-axis of the mechanical coordinate system of the detection equipment is: , the length L of AB is: .

[0024] ② Due to , then the coordinates of point C (X3, Y3) are: , .

[0025] ③From the known conditions, we can get: therefore, .

[0026] ④ Also because , set as formula (1), but ; because , set as formula (2); Similarly: .

[0027] ⑤ Also because , set as formula (3), therefore, Formula (1) is transformed into: , set as formula (4); Formula (2) is transformed into: , set as formula (5); Formula (3) is transformed into: , as formula (6).

[0028] ⑥ From formula (4)-formula (5), we get: , set as formula (7); From formula (4) to formula (6), we can get: , set as formula (8).

[0029] ⑦ Note: , Then formula (7) becomes , set as formula (9) , set as formula (10); From formula (9), we get: , as formula (11).

[0030] ⑧ Substituting formula (11) into formula (10), we get: , Right now , Right now , therefore, , find the Y value and then plug it into formula (11) to get the X value.

[0031] In a specific implementation, for example, the side length L of the V-frame is 10.3923 mm, the angle β is 60°, the angle α is 30°; the radius r of the lens is 3 mm; the coordinates of each point are measured: ball A (-4.5963, -38567), ball B (5.6382, -2.0521). The coordinates of point C (-1.0419, 5.9088) are obtained by , Calculated. The parameters are as follows Table 1 Substituting the specific parameters into the above lens center coordinate calculation equation, the lens center Q coordinate can be calculated as (0, 0).

[0032] The above description is only a preferred embodiment of the present invention. For ordinary technicians in this field, according to the teachings of the present invention, designing a method for centering a circular plane lens in different forms does not require creative labor. Without departing from the principles and spirit of the present invention, all equal changes, modifications, substitutions and variations made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for centering a circular plane lens, comprising an auxiliary device, characterized in that: The auxiliary device comprises a supporting base plate, a V-shaped frame is fixed on the upper surface of the supporting base plate, and standard balls A and B are respectively arranged at the ends of the rods on both sides of the V-shaped frame. The method steps are as follows: 1) Establish a coordinate calculation template through geometric algorithm, and record the auxiliary device angle α, angle β and side length L, where angle β is the angle of the V-frame and angle α is half of the angle of the V-frame; 2) Measure the radius of the lens and record the measurement; 3) Place the lens into the V-shaped frame of the auxiliary device so that the outer diameter of the lens is tangent to the two side rods of the V-shaped frame; 4) Use plasticine or soft red wax to fix the lens; 5) Place the auxiliary device with the lens fixed on the stage of the measuring equipment; 6) Measure the coordinates of the two-dimensional geometric center points of the standard sphere A and the standard sphere B respectively, and record the X and Y values ​​of the coordinates of the standard sphere A and the standard sphere B, and simultaneously calculate the coordinate position of the vertex C of the V-shaped frame; 7) Input the coordinate values ​​of standard sphere A and standard sphere B into the calculation template to obtain the X and Y coordinate values ​​of the center of the lens; 8) Enter the calculated coordinate value on the measuring device, move the probe to the coordinate, define it as the origin, and after focusing, measure along the set path.

2. A method for centering a circular plane lens according to claim 1, characterized in that: The ends of the two side rods of the V-shaped frame are both provided with mounting parts, and the standard ball A and the standard ball B are installed in the corresponding mounting parts.

3. A method for centering a circular plane lens according to claim 2, characterized in that: The bottom surface of the supporting base plate and the lower side of the mounting portion are provided with countersunk holes, and top pieces for supporting the standard balls A and B are installed in the countersunk holes.

4. A method for centering a circular plane lens according to claim 1, 2 or 3, characterized in that: The V-shaped frame is replaced by an isosceles triangle frame, and the supporting bottom plate is provided with a hollow portion.

5. A method for centering a circular plane lens according to claim 1, 2 or 3, characterized in that: The angle β is 60°, and the angle α is 30°.

6. A method for centering a circular plane lens according to claim 5, characterized in that: The analytical process of the calculation equation of the lens center coordinates is as follows: 1) Assume that the coordinates of the standard sphere A are (X1, Y1), and the coordinates of the standard sphere B are (X2, Y2); the coordinates of the vertex C of the V-shaped frame are (X3, Y3); point C, the standard spheres A and B form an equilateral triangle, any angle of which is represented by ∠β, and any side length is represented by AC, then AC=BC=AB; 2) Since the lens is tangent to both sides of the V-frame, assume that the tangent point intersects AC at point P2 and BC at point P3. The radius of the lens is represented by r, the center of the lens is Q, connect CQ, AQ, and BQ, then CQ is the angle bisector of ∠β, AQ=BQ; the center of the lens is Q and the coordinates are (X, Y) and are calculated as follows: ① The angle θ between the line AB and the X-axis of the mechanical coordinate system of the testing equipment is: , the length L of AB is: ; because , then the coordinates of point C (X3, Y3) are: ， ； ② Based on the known conditions, we can get: ,so ; Also because , set as formula (1), but ; ③ Due to , set as formula (2), Similarly: ; ④ Also because , set as formula (3), therefore, Formula (1) is transformed into: , set as formula (4); Formula (2) is transformed into: , set as formula (5); Formula (3) is transformed into: , set as formula (6); From formula (4)-formula (5), we can get: , set as formula (7); From formula (4) to formula (6), we can get: , set as formula (8); ⑤ Note: ， Then formula (7) becomes , set as formula (9); , set as formula (10); From formula (9), we get: , set as formula (11); ⑥ Substituting formula (11) into formula (10), we get: , Right now , Right now , therefore, , find the Y value and then plug it into formula (11) to get the X value.

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