A device and method for measuring edge thickness difference of large-aperture lens

Abstract

The invention relates to a device for measuring the edge thickness difference of a large-aperture lens, comprising a carrier positioning module, a platform support module, a linear positioning module and a measuring head module. The platform support module is placed in the carrier positioning module, the linear positioning modules are placed on both sides of the carrier positioning module, and the measuring head module is placed on the linear positioning module. The platform support module is adjusted, and the linear positioning module and the measuring head module are moved to match the edges of lenses with different diameters for measuring points. The carrier positioning module is used for safely and stably taking and placing the lens, avoiding contact contamination of the lens mirror surface and scratches on the mirror surface caused by measurement friction during measurement; the linear positioning module fixes and mechanically positions lenses with different diameters; the platform support module ensures the stability of the platform in placing and rotating the lens, effectively avoiding scrapping caused by contact contamination of the mirror surface and scratches caused by measurement friction, and providing accurate rework correction amount and grinding azimuth, thereby sending them to a "CNC milling machine" for correction processing.

Description

Technical Field

[0001] The invention relates to a device and method for measuring edge thickness difference of a large-aperture lens. Background Art

[0002] At present, for lenses with a diameter less than 10mm, the transmission and reflection optical systems plus automatic angle rotation mechanisms can be used to conveniently measure them; for lenses with a diameter of more than 10mm and less than 120mm, the laser transmission method measuring instrument is used to calculate the inclination of the lens surface by measuring the deviation between the cross cursor and the absolute center of the image through the optical path; when measuring the surface of a large-diameter lens with a diameter of 300mm, due to its own weight, the friction between the contact surface below the lens and the instrument's object ring mouth during the rotation process can easily cause scratches on the coating film or damage to the lens body. In addition, lenses with a diameter of more than 120mm are prone to contamination of the mirror surface and scratches on the outer edge during the process of installing or removing the "stage", and are also prone to contamination of the mirror surface due to improper grasping; the larger the lens, the more obvious the disadvantages of bumps, contamination, and scratches. The structure of large-diameter lenses measured by laser has a large optical path system that determines the support frame to be huge, which is not suitable for placement in the measurement room at the production site; for manufacturers, the surface of the semi-finished product before polishing is in a rough state of frosted glass, and it is impossible to measure it using transmission or reflection optical methods. After the finished product is completed, abnormalities found during inspection and rework will inevitably increase the manufacturing cost. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a measuring device and a measuring method suitable for measuring the edge thickness difference of a large-aperture lens with a lens diameter of 170 to 300 mm, which can effectively avoid contact contamination of the mirror surface during measurement and scrapping of the mirror surface caused by friction during measurement.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a large-aperture lens edge thickness difference measurement device, characterized in that it includes:

[0005] The object positioning module comprises a bottom plate, a shell fixed on the bottom plate, and an annular glass frustum placed above the shell;

[0006] A platform support module, the platform support module includes a lifting device and a lens support platform, the lifting device drives the lens support platform to move up and down, the lifting device is placed in the shell of the object positioning module, and the lens support platform extends out of the shell of the object positioning module and is placed in the annular glass table;

[0007] A linear positioning module, wherein the linear positioning module comprises a linear positioning module bracket, a mobile positioning structure and a mobile measuring head adjustment structure, wherein the positioning module bracket is fixed to the bottom plate of the object-carrying positioning module and is placed on both sides of the object-carrying positioning module, and the mobile positioning structure and the mobile measuring head adjustment structure are respectively placed on a linear positioning module bracket and move back and forth along the linear positioning module bracket;

[0008] The measuring head module comprises a micrometer measuring head and a movable bracket for positioning the micrometer measuring head. The micrometer measuring head is placed on the movable bracket for positioning the dial head. The movable bracket for positioning the dial head is connected to the movable measuring head adjustment structure of the linear positioning module. The movable positioning structure of the linear positioning module and the movable bracket for positioning the dial head of the measuring head module form four-point positioning of the lens edge.

[0009] Furthermore, the lifting device of the platform support module includes a driving handwheel, a worm gear, a gear rack pair, a radial ball bearing, a thrust bearing and a linear bearing from bottom to top. The rack passes through the radial ball bearing, the thrust bearing and the linear bearing, and the driving handwheel is rotated. The movement of the worm gear drives the gear rack pair to move, thereby driving the lens support platform to move up and down.

[0010] Furthermore, the mobile positioning structure includes a supporting part and a positioning part, the positioning part includes a U-shaped elastic telescopic rod and an elastic pressure foot with a bearing, the elastic pressure foot with a bearing is fixed at the front end of the elastic telescopic rod, the linear positioning module bracket is provided with a linear guide rail and a slider, and the supporting part of the mobile positioning structure and the mobile measuring head adjustment structure are both fixed on the slider.

[0011] Furthermore, the meter head positioning movable bracket includes two measuring head assemblies with built-in bearings, and the measuring head assemblies are distributed on both sides of the micrometer measuring head.

[0012] Furthermore, it also includes an angle-dividing positioning device, one end of which is connected to the linear positioning module, and the other end is close to the side surface of the annular glass frustum.

[0013] Furthermore, the diameter of the large-aperture lens is D, wherein 170≤D≤300 mm.

[0014] Furthermore, the large-aperture lens includes a plano-convex lens, a plano-concave lens and an aspherical lens.

[0015] A method for measuring edge thickness difference of a large-aperture lens, characterized by comprising the following steps:

[0016] Step 1: Turn the driving hand wheel to raise the lens support, place the lens on the lens support, turn the driving hand wheel to lower the lens support to approach the annular glass table, move the positioning structure and the measuring head module to support the outer edge of the lens, and continue to turn the driving hand wheel until the lens is fully in contact with the annular glass table;

[0017] Step 2: After adjusting the micrometer measuring head in the measuring head module to the position of the lens to be measured, dot the first point for measurement, and control the micrometer to have a 0.1mm press-in amount, and make a starting position mark on the outer cylindrical surface of the lens as the azimuth angle 0 degree position;

[0018] Step 3: Lift the dial gauge head, turn it 45 degrees, and then lower the dial gauge head to measure the second point;

[0019] Step 4: Repeat step 3 and measure the 3rd, 4th, 5th, 6th, 7th and 8th points in sequence;

[0020] Step 5: Record the data of 8 points and pass the eight-point data to the "Lvovich Chebyshev fitting approximation polynomial algorithm" to obtain the polynomial fitting function y=a5·x about the fifth power of height y and rotation angle x. 5 +a4·x 4 +a3·x 3 +a2·x 2 + a1·x+a0, taking the derivative of this formula we get a quartic equation. The two real roots obtained by solving the quartic equation using Ferrari's algorithm are the required maximum and minimum values ​​and the corresponding rotation angle positions.

[0021] Furthermore, the step 1 includes the following steps:

[0022] Step a: Turn the driving hand wheel to drive the worm and worm gear to move, and then drive the gear rack structure to rotate the lens support, and lay a capacitor paper with a thickness of 0.02mm on the lens support;

[0023] Step b: Place the lens on the lens support, and turn the driving hand wheel to lower the lens support until the bottom surface of the lens is close to the upper surface of the annular glass cone;

[0024] Step c: Move the linear positioning module so that the elastic pressure foot with a bearing in the movable positioning structure presses against the outer edge of the lens, and the measuring head assembly of the measuring head module presses against the outer edge of the lens;

[0025] Step d: Turn the driving hand wheel to lower the lens support until the lower surface of the lens is in full contact with the annular glass cone.

[0026] Furthermore, the position to be measured in step 2 is in an annular area near the outer edge of the lens.

[0027] Beneficial effects of the present invention:

[0028] (1) Through the object positioning module and the linear positioning module, the scrapping caused by contact contamination of the mirror surface and scratches caused by measurement friction can be effectively avoided;

[0029] (2) It is suitable for measuring the edge thickness difference between semi-finished products and finished products in the production process. Through software calculation, it provides accurate rework correction amount and grinding azimuth, which can be sent to the "CNC milling machine" for correction processing;

[0030] (3) The device is small in size and low in cost, making it suitable for online testing in optical manufacturers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0032] Figure 1 It is a schematic diagram of the structure of the present invention;

[0033] Figure 2 is a cross-sectional view of the present invention;

[0034] Figure 3 It is a structural schematic diagram of the object positioning module of the present invention;

[0035] Figure 4 It is a schematic diagram of the structure of the platform support module of the present invention;

[0036] Figure 5 It is a schematic diagram of the structure of the linear positioning module of the present invention;

[0037] Figure 6 It is a schematic diagram of the structure of the measuring head module of the present invention;

[0038] Figure 7 It is a schematic diagram of the structure of the table head positioning mobile bracket of the present invention;

[0039] Figure 8 is a schematic diagram of a measurement area in a measurement example of the present invention;

[0040] Fig. 9 It is a schematic diagram of eight-point measurement in a measurement example of the present invention;

[0041] Fig.10 It is an eight-point curve fitting diagram in the measurement example of the present invention. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0043] like Figure 1A device for measuring the edge thickness difference of a large-aperture lens is shown, wherein the large-aperture lens includes a plano-convex lens, a plano-concave lens and an aspherical mirror, and the diameter of the large-aperture lens is D, wherein 170≤D≤300mm, and the measuring device includes a load positioning module, a platform support module, a linear positioning module and a measuring head module, wherein the platform support module is placed in the load positioning module, the linear positioning modules are placed on both sides of the load positioning module, and the measuring head module is placed on the linear positioning module, and the platform support module is adjusted, and the linear positioning module and the measuring head module are moved to match the edges of lenses of different diameters for measuring points, and the load positioning module is used to safely and smoothly take and place the lens, and avoid contact contamination of the lens mirror surface during measurement and scratches on the mirror surface caused by measurement friction; the linear positioning module fixes and mechanically positions lenses of different diameters; and the platform support module ensures the stability of the platform in placing and rotating the lens. It also includes an angle-dividing positioning device 50, wherein one end of the angle-dividing positioning device 50 is connected to the linear positioning module, and the other end is close to the side surface of the annular glass truncated table 13.

[0044] like Figure 1 , 2 3 shows an object positioning module, which includes a base plate 11, a shell 12 fixed on the base plate 11, and an annular glass cone 13 placed above the shell 12. The optimal flatness of the annular glass cone 13 is 0.002.

[0045] like Figure 1 , 2 4, comprises a lifting device and a lens support 21, the lifting device drives the lens support 21 to move up and down, the lifting device is placed in the shell 12 of the object positioning module, the lens support 21 extends out of the shell 12 of the object positioning module and is placed in the annular glass table 13, the lifting device comprises a driving hand wheel 22, a worm gear 23, a gear rack pair 24, a radial ball bearing 25, a thrust bearing 26 and a linear bearing 27 from bottom to top, the rack passes through the radial ball bearing 25, the thrust bearing 26 and the linear bearing 27, the driving hand wheel 22 is rotated, the worm gear 23 moves, the gear rack pair 24 moves, and thus the lens support 21 moves up and down.

[0046] like Figure 1 , 2, 5, the linear positioning module comprises a linear positioning module bracket 31, a mobile positioning structure 32 and a mobile measuring head adjustment structure 33, the positioning module bracket 31 is fixed on the bottom plate 11 of the object-carrying positioning module and is placed on both sides of the object-carrying positioning module, the mobile positioning structure 32 and the mobile measuring head adjustment structure 33 are respectively placed on a linear positioning module bracket 31 and move back and forth along the linear positioning module bracket 31. The mobile positioning structure 32 comprises a support portion 321 and a positioning portion, the positioning portion comprises a U-shaped elastic telescopic rod 322 and an elastic pressure foot 323 with a bearing, the elastic pressure foot 323 with a bearing is fixed to the front end of the elastic telescopic rod 322, the linear positioning module bracket 31 is provided with a linear guide rail 311 and a slider 312, the support portion 321 of the mobile positioning structure 32 and the mobile measuring head adjustment structure 33 are both fixed on the slider 312.

[0047] like Figure 1 , 2 , 6, and 7, the measuring head module includes a micrometer measuring head 41 and a head positioning movable bracket 42, the micrometer measuring head 41 is placed on the head positioning movable bracket 42, the head positioning movable bracket 42 is connected to the mobile measuring head adjustment structure 33 of the linear positioning module, the head positioning movable bracket 42 includes two measuring head assemblies 421 with built-in bearings, the measuring head assemblies 421 are distributed on both sides of the micrometer measuring head 41, the mobile positioning structure 32 of the linear positioning module and the head positioning movable bracket 42 of the measuring head module form a four-point positioning of the lens edge.

[0048] A method for measuring edge thickness difference of a large-aperture lens comprises the following steps:

[0049] Step 1: Turn the driving hand wheel to raise the lens support, place the lens on the lens support, turn the driving hand wheel to lower the lens support to approach the annular glass table, move the positioning structure and the measuring head module to support the outer edge of the lens, and continue to turn the driving hand wheel until the lens is fully in contact with the annular glass table;

[0050] Step 2: After adjusting the micrometer measuring head in the measuring head module to the position of the lens to be measured, dot the first point for measurement, and control the micrometer to have a 0.1mm press-in amount, and make a starting position mark on the outer cylindrical surface of the lens as the azimuth angle 0 degree position;

[0051] Step 3: Lift the dial gauge head, turn it 45 degrees, and then lower the dial gauge head to measure the second point;

[0052] Step 4: Repeat step 3 and measure the 3rd, 4th, 5th, 6th, 7th and 8th points in sequence;

[0053] Step 5: Record the data of 8 points and pass the eight-point data to the "Lvovich Chebyshev fitting approximation polynomial algorithm" to obtain the polynomial fitting function y=a5·x about the fifth power of height y and rotation angle x. 5 +a4·x 4 +a3·x 3 +a2·x 2 + a1·x+a0, taking the derivative of this formula we get a quartic equation. The two real roots obtained by solving the quartic equation using Ferrari's algorithm are the required maximum and minimum values ​​and the corresponding rotation angle positions.

[0054] In the above steps, step 1 includes the following steps:

[0055] Step a: Turn the driving hand wheel to drive the worm and worm gear to move, and then drive the gear rack structure to rotate the lens support, and lay a capacitor paper with a thickness of 0.02mm on the lens support;

[0056] Step b: Place the lens on the lens support, and turn the driving hand wheel to lower the lens support until the bottom surface of the lens is close to the upper surface of the annular glass cone;

[0057] Step c: Move the linear positioning module so that the elastic pressure foot with a bearing in the movable positioning structure presses against the outer edge of the lens, and the measuring head assembly of the measuring head module presses against the outer edge of the lens;

[0058] Step d: Turn the driving hand wheel to lower the lens support until the lower surface of the lens is in full contact with the annular glass cone.

[0059] Figure 8 , 9 , 10 are examples of specific algorithms. In this example, the lens unloading stroke is 30 mm, the diameter of the annular glass cone is 140 mm, the micrometer range is 12.5 mm, the accuracy is 1.8 um, and the position of the lens to be measured is in the ring area near the outer edge of the lens. This example measures a lens with a diameter of 300 mm and an effective coating aperture of 286 mm. The data of 8 points measured in sequence are P0 (0, 0.1000), P1 (45, 0.1367), P2 (90, 0.1582), P3 (135, 0.1519), P4 (180, 0.1214), P5 (225, 0.0847), P6 (270, 0.0632), and P7 (315, 0.0695). According to the above steps, the maximum and minimum values ​​​​and the corresponding angular positions are calculated. The algorithm changes the traditional practice of repeatedly measuring by hand to find the highest and lowest points, reduces the damage to the glass surface, and realizes automatic measurement and calculation. The grinding position, direction and amount are calculated from the obtained data, and then sent to the "CNC milling machine" for processing to obtain qualified products.

[0060] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A device for measuring the edge thickness difference of a large-aperture lens, characterized in that: include: The object positioning module comprises a bottom plate, a shell fixed on the bottom plate, and an annular glass frustum placed above the shell; A platform support module, the platform support module includes a lifting device and a lens support platform, the lifting device drives the lens support platform to move up and down, the lifting device is placed in the shell of the object positioning module, and the lens support platform extends out of the shell of the object positioning module and is placed in the annular glass table; A linear positioning module, wherein the linear positioning module comprises a linear positioning module bracket, a mobile positioning structure and a mobile measuring head adjustment structure, wherein the positioning module bracket is fixed to the bottom plate of the object-carrying positioning module and is placed on both sides of the object-carrying positioning module, and the mobile positioning structure and the mobile measuring head adjustment structure are respectively placed on a linear positioning module bracket and move back and forth along the linear positioning module bracket; The measuring head module comprises a micrometer measuring head and a movable bracket for positioning the micrometer measuring head. The micrometer measuring head is placed on the movable bracket for positioning the micrometer measuring head. The movable bracket for positioning the micrometer measuring head is connected to the movable measuring head adjustment structure of the linear positioning module. The movable positioning structure of the linear positioning module and the movable bracket for positioning the micrometer measuring head of the measuring head module form a four-point positioning of the lens edge. The head positioning movable bracket includes two measuring head assemblies with built-in bearings, and the measuring head assemblies are distributed on both sides of the micrometer measuring head. It also includes an angle-dividing positioning device, one end of which is connected to the linear positioning module, and the other end of which is close to the side surface of the annular glass frustum.

2. A device for measuring edge thickness difference of a large-aperture lens according to claim 1, characterized in that: The lifting device of the platform support module includes a driving handwheel, a worm gear, a gear rack pair, a radial ball bearing, a thrust bearing and a linear bearing from bottom to top. The rack passes through the radial ball bearing, the thrust bearing and the linear bearing. When the driving handwheel is rotated, the movement of the worm gear drives the gear rack pair to move, thereby driving the lens support platform to move up and down.

3. The device for measuring edge thickness difference of a large-aperture lens according to claim 1, characterized in that: The mobile positioning structure includes a supporting part and a positioning part. The positioning part includes a U-shaped elastic telescopic rod and an elastic pressure foot with a bearing. The elastic pressure foot with a bearing is fixed to the front end of the elastic telescopic rod. The linear positioning module bracket is provided with a linear guide rail and a slider. The supporting part of the mobile positioning structure and the mobile measuring head adjustment structure are both fixed on the slider.

4. The device for measuring edge thickness difference of a large-aperture lens according to claim 1, characterized in that: The diameter of the large-aperture lens is D, wherein 170≤D≤300 mm.

5. The device for measuring edge thickness difference of a large-aperture lens according to claim 1, characterized in that: The large-aperture lens includes a plano-convex lens, a plano-concave lens and an aspherical lens.

6. A method for measuring the edge thickness difference of a large-aperture lens, used in the measuring device as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Turn the driving hand wheel to raise the lens support, place the lens on the lens support, turn the driving hand wheel to lower the lens support to approach the annular glass table, move the positioning structure and the measuring head module to support the outer edge of the lens, and continue to turn the driving hand wheel until the lens is fully in contact with the annular glass table; Step 2: After adjusting the micrometer measuring head in the measuring head module to the position of the lens to be measured, dot the first point for measurement, and control the micrometer to have a 0.1mm press-in amount, and make a starting position mark on the outer cylindrical surface of the lens as the azimuth angle 0 degree position; Step 3: Lift the dial gauge head, turn it 45 degrees, and then lower the dial gauge head to measure the second point; Step 4: Repeat step 3 and measure the 3rd, 4th, 5th, 6th, 7th and 8th points in sequence; Step 5: Record the data of 8 points and pass the eight-point data to the "Lvovich Chebyshev fitting approximation polynomial algorithm" to obtain the polynomial fitting function y=a5·x about the fifth power of height y and rotation angle x. 5 +a4·x 4 +a3·x 3 +a2·x 2 + a1·x+a0, taking the derivative of this formula we get a quartic equation. The two real roots obtained by solving the quartic equation using Ferrari's algorithm are the required maximum and minimum values ​​and the corresponding rotation angle positions.

7. A method for measuring edge thickness difference of a large-aperture lens according to claim 6, characterized in that: The step 1 includes the following steps: Step a: Turn the driving hand wheel to drive the worm and worm gear to move, and then drive the gear rack structure to rotate the lens support, and lay a capacitor paper with a thickness of 0.02mm on the lens support; Step b: Place the lens on the lens support, and turn the driving hand wheel to lower the lens support until the bottom surface of the lens is close to the upper surface of the annular glass cone; Step c: Move the linear positioning module so that the elastic pressure foot with a bearing in the movable positioning structure presses against the outer edge of the lens, and the measuring head assembly of the measuring head module presses against the outer edge of the lens; Step d: Turn the driving hand wheel to lower the lens support until the lower surface of the lens is in full contact with the annular glass cone.

8. A method for measuring edge thickness difference of a large-aperture lens according to claim 6, characterized in that: The position to be measured in step 2 is in the annular area near the outer edge of the lens.

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