A method of centering a circular planar lens

Abstract

The present application relates to the field of precision measurement, in particular to a kind of method for centering circular plane lens, method steps are as follows: the coordinate calculation template is established by geometric algorithm, and angle α, angle β and side length L of auxiliary device are recorded;The radius of the lens is measured and the measured value is recorded;The lens is placed in the V-shaped frame of the auxiliary device, so that the outer diameter of the lens is tangent to the two sides of the rod;Use plasticine or soft red wax to fix the lens;The auxiliary device with the fixed lens is placed on the measuring equipment stage;The two-dimensional geometric position center point coordinates of standard ball A and standard ball B are measured respectively, and the coordinates X and Y of standard ball A and standard ball B are recorded, and the coordinate position of the vertex C of point V-shaped frame is obtained;The coordinate values of standard ball A and standard ball B are input into the calculation template, and the coordinate X and Y of the lens center are obtained.The method can be used for contact measurement equipment with only upper surface probe to define lens center point.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precision measurement, in particular to a method for centering a circular plane lens. BACKGROUND

[0002] With the continuous iterative development of the optical field, its application range is also 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 use scenarios. The surface shape precision of the lens often needs high-precision measuring equipment to check whether it meets the design requirements. In high-precision surface detection equipment, it is generally divided into contact type and non-contact type (the following is described for contact type equipment).

[0003] In the process of measuring the surface of the lens by the contact type equipment (taking Matsushita-UA3P as an example), centering (which can be understood as defining the origin or starting point) is a key link in the measurement process, which often depends on the upper surface probe of the equipment to define the physical highest / lowest point of the measured product, or to define the center according to the related design parameters.

[0004] However, no matter which measurement method is selected, the center position must be defined first. Note: The above centering is not an absolute center position (which does not actually exist), but the center position is controlled within a set error range. (For example: the error range is set to 2um, when the actual center deviates from the theoretical center ≤2um, it is considered that the centering is completed.) Therefore, when the lens is changed to a plane or a near plane (for example: a spherical surface or an aspheric surface with a curvature radius R of 20000mm), the center cannot be accurately defined according to the existing method, which causes the measurement path to be unable to be correctly selected, resulting in that the lens cannot be measured or the data is distorted. Therefore, the method for centering the circular plane (near plane) lens becomes crucial. SUMMARY

[0005] The purpose of the present application is to provide a method for centering a circular plane lens, which can be used for a contact type measuring equipment with only an upper surface probe to define the center point of the lens.

[0006] The technical solution of the present application is: a method for centering a circular plane lens, comprising an auxiliary device, the auxiliary device comprises a supporting bottom plate, a V-shaped frame is fixed on the upper surface of the supporting bottom plate, standard balls A and B are arranged at the both sides of the rod end of the V-shaped frame, and the method steps are as follows:

[0007] 1) A coordinate calculation template is established by a geometric algorithm, and the angle α, the angle β and the side length L of the auxiliary device are recorded, wherein the angle β is the included angle of the V-shaped frame, and the angle α is half of the included angle of the V-shaped frame;

[0008] 2) Measure the radius of the lens and record the measurement;

[0009] 3) Put 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;

[0010] 4) Fix the lens using plasticine or soft red wax;

[0011] 5) Put the auxiliary device with the fixed lens into the stage of the measuring equipment;

[0012] 6) Measure the two-dimensional geometric position center coordinates of standard sphere A and standard sphere B respectively, and record the coordinate X value and Y value of standard sphere A and standard sphere B, and simultaneously calculate the coordinate position of the vertex C of the V-shaped frame;

[0013] 7) Input the coordinate values of standard sphere A and standard sphere B into the calculation template to obtain the coordinate X value and Y value of the lens center;

[0014] 8) Input the calculated coordinate values on the measuring equipment, move the probe above the coordinate to define it as the origin, and after focusing, measure along the set path.

[0015] Further, the ends of the two side rods of the V-shaped frame are provided with mounting parts, and the standard sphere A and the standard sphere B are mounted in the corresponding mounting parts.

[0016] Further, the bottom surface of the supporting bottom plate and the lower side of the mounting part are provided with counterbores, and the counterbores are provided with top pieces for pressing against the standard sphere A and the standard sphere B.

[0017] Further, the V-shaped frame is replaced by an isosceles triangular frame, and the supporting bottom plate is provided with a hollow part.

[0018] Further, the angle β is 60°, and the angle α is 30°.

[0019] Further, the calculation equation analysis process of the lens center coordinate is as follows:

[0020] 1) Assume that the coordinates of standard sphere A are (X1, Y1), the coordinates of standard sphere B are (X2, Y2), and the coordinates of the vertex C of the V-shaped frame are (X3, Y3); point C and standard sphere A and standard sphere B form an equilateral triangle, any angle is represented by ∠β, and any side length is represented by AC, so AC = BC = AB;

[0021] 2) Since the lens is tangent to the two sides of the V-shaped frame, assume that the tangent points intersect AC at point P2 and BC at point P3, the radius of the lens is represented by r, the lens center is Q, and CQ, AQ, and BQ are connected, then CQ is the angle bisector of ∠β, AQ = BQ; the coordinates of the lens center Q are (X, Y) and are calculated as follows:

[0022] The angle θ between the line AB and the X axis of the mechanical coordinate system of the detection device is: The length L of AB is: Since The coordinates (X3, Y3) of point C are:

[0023] X3 = X1 + L x cos(θ + β), Y3 = Y1 + L x sin(θ + β);

[0024] From the known conditions, we have: Therefore Since Let it be formula (1),

[0025] Then AQ 2 = AC 2 + CQ 2 - 2 x |AC| x |CQ| x cos α;

[0026] Since Let it be formula (2),

[0027] Similarly: BQ 2 = BC 2 + CQ 2 - 2 x |AC| x |CQ| x cos α;

[0028] Since Let it be formula (3), therefore,

[0029] Formula (1) becomes: X3 2 - 2X3X + X 2 + Y3 2 - 2Y3Y + Y 2 = |CQ| 2 Let it be formula (4);

[0030] Formula (2) becomes: X1 2 - 2X1X + X 2 + Y1 2 - 2Y1Y + Y 2 = |AQ| 2 Let it be formula (5);

[0031] Formula (3) becomes: X2 2 - 2X2X + X 2 + Y2 2 - 2Y2Y + Y 2 = |BQ| 2 Let it be formula (6);

[0032] From formula (4) to formula (5), we have:

[0033] X3 2- X1 2 - 2(X3-X1)X+Y3 2 - Y1 2 - 2(Y3-Y1)Y = |CQ| 2 - |AQ| 2 , is given as equation (7);

[0034] From equations (4) - (6) we have:

[0035] X3 2 - X2 2 - 2(X3-X2)X+Y3 2 - Y2 2 - 2(Y3-Y2)Y = |BQ| 2 - |BQ| 2 , is given as equation (8);

[0036] (5) Let:

[0037] X3 2 - X1 2 + Y3 2 - Y1 2 = a

[0038] 2 x (X3-X1) = b

[0039] 2 x (Y3-Y1) = c

[0040] |CQ| 2 - |AQ| 2 = d

[0041] X3 2 - X2 2 + Y3 2 - Y2 2 = e

[0042] 2 x (X3-X2) = f

[0043] 2 x (Y3-Y2) = g

[0044] |CQ| 2 - |BQ| 2 = h, then equation (7) becomes a - bX - cY = d, given as equation (9); e - fX - gY = h, given as equation (10); from equation (9) we have: given as equation (11);

[0045] (6) Substituting equation (11) into equation (10) we have: i.e. eb - fa + fd + fc Y - gbY = hb, i.e. (fc - gb) x Y = hb - eb + fa - fd,

[0046] Therefore, After the Y value is obtained, the X value can be obtained by substituting the Y value into equation (11).

[0047] Compared with the prior art, the present application has the following advantages:

[0048] The basic principle of the method is based on the fixed triangular relationship of two standard balls (the center points of the balls are easily measured by the upper surface probe) and the V-shaped groove, combined with the actual radius of the lens, to accurately calculate the center position of the lens through geometric algorithm. The single upper surface probe device realizes micron-level centering effect on the special surface and shape of the circular lens. The centering precision is high (the auxiliary device is processed by super-precision equipment, the error is <1 um, the lens roundness is generally <1 um, the detection equipment error is <50 nm, and the centering comprehensive precision is <3 um), and it is simple, convenient and easy to operate. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 It is a schematic diagram of the existing upper surface probe;

[0050] Figure 2 It is an example of the probe detecting the surface of different shaped lenses;

[0051] Figure 3 It is an example of the center point position of different types of lenses;

[0052] Figure 4 It is a schematic diagram of the path selection of the existing contact type device for measuring the surface of the lens;

[0053] Figure 5 It is a schematic diagram of the auxiliary device structure of the present application;

[0054] Figure 6 It is a sectional view of the auxiliary device of the present application;

[0055] Figure 7 It is a schematic diagram of the lens placed on the auxiliary device and fixed by red wax and then placed in the measuring device of the present application;

[0056] Figure 8 It is a schematic diagram of the standard ball A, ball B, point C and the tangent point of the lens and each edge of the present application;

[0057] Figure 9 It is a coordinate diagram of the ball A, ball B and point C of the present application;

[0058] In the figure: 1-lens 2-plaster or soft red wax 10-auxiliary device 11-reliance bottom plate 12-V-shaped frame 13-standard ball A 14-standard ball B 15-mounting part 16-counterbore 17-top piece. DETAILED DESCRIPTION

[0059] In order to make the above features and advantages of the present application more apparent, the following embodiments are described in detail below, with reference to the accompanying drawings, but the present application is not limited thereto.

[0060] Reference Figures 5 to 9

[0061] A method for centering a circular flat lens, comprising an auxiliary device 10, the auxiliary device comprising a supporting base plate 11, a V-shaped frame 12 fixed on the upper surface of the supporting base plate, standard ball A 13 and standard ball B 14 arranged on both sides of the V-shaped frame, the method steps are as follows:

[0062] 1) A coordinate calculation template is established by a geometric algorithm, and the angle α, angle β and side length L of the auxiliary device are recorded (constant, only input once), wherein the angle β is the included angle of the V-shaped frame, and the angle α is half of the included angle of the V-shaped frame; specifically, the angle β is 60°, and the angle α is 30°.

[0063] 2) The radius of the lens is measured and the measured value is recorded;

[0064] 3) The lens 1 is placed in 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;

[0065] 4) The lens is fixed using plasticine or soft red wax 2;

[0066] 5) The auxiliary device with the fixed lens is placed on the stage of the measuring equipment, and the approximate direction is as follows Figure 7 .

[0067] 6) The two-dimensional geometric position center coordinates of the standard ball A and the standard ball B are measured respectively, and the coordinates X and Y of the standard ball A and the standard ball B are recorded, and the coordinate position of the vertex C of the V-shaped frame is simultaneously obtained.

[0068] 7) The coordinate values of the standard ball A and the standard ball B are input into the calculation template to obtain the coordinate X and Y of the lens center;

[0069] 8) The calculated coordinate values are input on the measuring equipment, the probe is moved above the coordinate, which is defined as the origin, and after focusing, the path can be measured according to the set path.

[0070] In the embodiment, the two 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.

[0071] In the embodiment, the bottom surface of the supporting base plate and the lower side of the mounting portion are provided with counterbores 16, and the counterbores are provided with top pieces 17 for pressing against the standard ball A and the standard ball B, so as to fix the standard ball A and the standard ball B, and the upper surfaces of the standard ball A and the standard ball B are exposed to the mounting holes arranged on the mounting portions.

[0072] In another embodiment, the V-shaped frame can be designed as an isosceles triangle frame according to actual needs, and the bearing bottom plate can be hollowed out to avoid the lens shape.

[0073] In this embodiment, the calculation equation of the lens center coordinates is as follows:

[0074] It is known that:

[0075] 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 by step 6);

[0076] The coordinates of the vertex C of the V-shaped frame are (X3, Y3); point C and the standard sphere A and the standard sphere B form an equilateral triangle, any angle of which is denoted by ∠β, and any side length is denoted by AC, then AC = BC = AB; — ∠β and the side length AC are design values, which can be obtained by auxiliary devices;

[0077] 2) Since the lens is tangent to the two sides of the V-shaped frame, assume that the tangent points intersect AC at point P2 and BC at point P3, the radius of the lens is denoted 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 lens radius r is obtained by step 2), and ∠α = 1 / 2∠β.

[0078] 3) The coordinates of the lens center Q are (X, Y) and are calculated as follows:

[0079] ① Since the sphere A and the sphere B form an equilateral triangle with point C, the sphere A (X1, Y1) and the sphere B (X2, Y2) are known;

[0080] Therefore, the angle θ between the line AB and the X-axis of the mechanical coordinate system of the detection device is:

[0081] The length L of AB is:

[0082] ② Since The coordinates (X3, Y3) of point C are:

[0083] X3 = X1 + L × cos(θ + β), Y3 = Y1 + L × sin(θ + β).

[0084] ③ From the known conditions, we have: Therefore,

[0085] ④ Since Let it be formula (1),

[0086] Then AQ 2 = AC 2 +CQ2 -2 x |AC| x |CQ| x cos a;

[0087] Since Let be formula (2);

[0088] Similarly: BQ 2 = BC 2 + CQ 2 -2 x |AC| x |CQ| x cos a.

[0089] Since Let be formula (3), therefore,

[0090] Formula (1) becomes: X3 2 -2 X3X + X 2 + Y3 2 -2 Y3Y + Y 2 = |CQ| 2 Let be formula (4);

[0091] Formula (2) becomes: X1 2 -2 X1X + X 2 + Y1 2 -2 Y1Y + Y 2 = |AQ| 2 Let be formula (5);

[0092] Formula (3) becomes: X2 2 -2 X2X + X 2 + Y2 2 -2 Y2Y + Y 2 = |BQ| 2 Let be formula (6).

[0093] From formula (4) to formula (5):

[0094] X3 2 - X1 2 -2 (X3- X1)X + Y3 2 - Y1 2 -2 (Y3- Y1)Y = |CQ| 2 - |AQ| 2 Let be formula (7);

[0095] From formula (4) to formula (6):

[0096] X3 2 - X2 2 -2 (X3- X2)X + Y3 2 - Y2 2 -2 (Y3- Y2)Y = |CQ| 2 - |BQ| 2 Let be formula (8).

[0097] ⑦ Note:

[0098] X3 2 -X1 2 +Y3 2 -Y1 2 =a

[0099] 2×(X3-X1)=b

[0100] 2×(Y3-Y1)=c

[0101] |CQ| 2 -|AQ| 2 =d

[0102] X3 2 -X2 2 +Y3 2 -Y2 2 =e

[0103] 2×(X3-X2)=f

[0104] 2×(Y3-Y2)=g

[0105] |CQ| 2 -|BQ| 2 =h,

[0106] Then equation (7) is transformed into a-bX-cY=d, which is set as equation (9); e-fX-gY=h, which is set as equation (10);

[0107] From equation (9), we get: Let it be equation (11);

[0108] ⑥ Substituting equation (11) into equation (10), we get:

[0109] That is, eb-fa+fd+fcY-gbY=hb,

[0110] That is (fc-gb)×Y=hb-eb+fa-fd,

[0111] therefore, The X value can be obtained by substituting the Y value into equation (11).

[0112] In a specific embodiment, for example: the side length L of the V-shaped frame is 10.3923 mm, the angle β is 60°, and the angle α is 30°; the radius r of the lens is 3 mm; the coordinates of each point are measured as: sphere A (-4.5963, -38567), sphere B (5.6382, -2.0521). The point C coordinate (-1.0419, 5.9088) is calculated by X3=X1+L×cos(θ+β), Y3=Y1+L×sin(θ+β). The parameters are as shown in Table 1

[0113]

[0114] The specific parameters are substituted into the calculation equation of the lens center coordinate to calculate the lens center Q coordinate (0, 0).

[0115] The above only describes the preferred embodiments of the present application. According to the teachings of the present application, a person of ordinary skill in the art can design a different form of a method for centering a circular planar lens without creative labor, and any equivalent changes, modifications, replacements, and variations made within the scope of the present application should be included in the scope of the present application.

Claims

1. A method of centering a circular planar lens comprising an auxiliary device, characterized in that, The auxiliary device comprises a bearing bottom plate, a V-shaped frame is fixed on the upper surface of the bearing bottom plate, standard ball A and standard ball B are arranged on the two side rod ends of the V-shaped frame, and the method steps are as follows: 1) A coordinate calculation template is established by a geometric algorithm, and the angle α, angle β and side length L of the auxiliary device are recorded, wherein the angle β is the included angle of the V-shaped frame, and the angle α is half of the included angle of the V-shaped frame; the angle β is 60°, and the angle α is 30°; 2) The radius of the lens is measured and the measurement value is recorded; 3) The lens is placed in 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) The lens is fixed by using plasticine or soft red wax; 5) The auxiliary device with the fixed lens is placed on the object table of the measuring equipment; 6) The two-dimensional geometric position center coordinates of the standard ball A and the standard ball B are measured respectively, and the coordinates X and Y of the standard ball A and the standard ball B are recorded, and the coordinate position of the vertex C of the V-shaped frame is synchronously obtained; 7) The coordinate values of the standard ball A and the standard ball B are input into the calculation template, and the coordinate X and Y of the lens center are obtained; the calculation equation analysis process of the lens center coordinate is as follows: 1) Assuming that the coordinates of the standard ball A are (X1, Y1), the coordinates of the standard ball B are (X2, Y2), and the coordinates of the vertex C of the V-shaped frame are (X3, Y3); the standard ball A, the standard ball B and the vertex C of the V-shaped frame form an equilateral triangle, and any angle is represented by ∠β, and any side length is represented by AC, so that AC=BC=AB; 2) Since the lens is tangent to the two sides of the V-shaped frame, it is assumed 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 lens center is Q, CQ, AQ and BQ are connected, CQ is the angle bisector of ∠β, AQ=BQ; the lens center is Q, and the coordinates (X, Y) are calculated as follows: The angle θ between the line AB and the X axis of the mechanical coordinate system of the detection device is: The length L of the line AB is: Since The coordinates (X3, Y3) of the point C are: X3=X1+L×cos(θ+β), Y3=Y1+L×sin(θ+β); (2) From the known conditions, we have: Therefore Also, since Let be of the form (1), then AQ 2 = AC 2 + CQ 2 - 2 x |AC| x |CQ| x cos a; ③Because is set to formula (2), Similarly: BQ 2 = BC 2 + CQ 2 - 2 x |AC| x |CQ| x cos a; (4) Further, since is set to formula (3), thus, X3 2 -2X3X+X 2 +Y3 2 -2Y3Y+Y 2 = |CQ| 2 , is given as formula (4); X1 2 -2X1X+X 2 +Y1 2 -2Y1Y+Y 2 = | AQ | 2 , is given as formula (5); X2 2 -2X2X+X 2 +Y2 2 -2Y2Y+Y 2 = |BQ| 2 , is given as equation (6); From equation (4) to equation (5): X3 2 - X1 2 - 2(X3- X1)X + Y3 2 - Y1 2 - 2(Y3- Y1)Y = |CQ| 2 - |AQ| 2 , set as Equation (7); From equation (4) to equation (6): X3 2 - X2 2 - 2(X3- X2)X + Y3 2 - Y2 2 - 2(Y3- Y2)Y = |CQ| 2 - |BQ| 2 , set as Equation (8); ⑤Record: X3 2 - X1 2 + Y3 2 - Y1 2 = a 2×(X3-X1)=b 2×(Y3-Y1)=c |CQ| 2 -|AQ| 2 = d X3 2 - X2 2 + Y3 2 - Y2 2 = e 2×(X3-X2)=f 2×(Y3-Y2)=g |CQ| 2 -|BQ| 2 = h, then equation (7) becomes a-bX-cY=d, which is equation (9); e-fX-gY=h, which is equation (10); from equation (9) we have: which is equation (11); (6) Substitute equation (11) into equation (10) to get: i.e., eb-fa+fd+fc Y-gb Y=hb, That is, (fc-gb)×Y=hb-eb+fa-fd, Thus, After the value of Y is found, the value of X can be found by substituting into equation (11). 8) The calculated coordinate values are input on the measuring equipment, the probe is moved above the coordinate, which is defined as the origin, and after focusing, the path can be measured according to the set path.

2. The method of centering a round, flat lens of claim 1, wherein, The two side rod ends of the V-shaped frame are provided with mounting parts, and the standard ball A and the standard ball B are mounted in the corresponding mounting parts.

3. A method of centering a circular planar lens according to claim 2, wherein, The bottom surface of the bearing bottom plate and the lower side of the mounting part are provided with counterbores, and the counterbores are provided with top pieces for pressing the standard ball A and the standard ball B.

4. A method of centering a circular planar lens according to claim 1, 2 or 3, wherein, The V-shaped frame is replaced by an isosceles triangular frame, and the bearing bottom plate is provided with a hollow part.

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