Real-time eccentricity detection system

Abstract

The invention discloses a real-time eccentricity detection system. The system comprises a light source; a light beam emitted by the light source sequentially passes through the first linear polarizer, the uniaxial crystal, the to-be-detected lens and the second linear polarizer to form an interference pattern; the polarization direction of the first linear polarizer is perpendicular to the polarization direction of the second linear polarizer. The light-emitting face of the light source is perpendicular to the center line of the light beam. The eccentric state can be visually displayed in real time without rotating the lens or the lens group to be detected, the optical axis eccentricity of the lens or the lens group caused by inclination or eccentricity can be detected at a time, the eccentric detection precision is high, the operation cost is effectively reduced, the detection efficiency is improved, the structure is simple, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the field of optical detection, and particularly to a real-time eccentricity detection system. Background Art

[0002] In recent years, with the development of the digital information industry, the application demands of various types of lenses such as industrial lenses, surveillance lenses, and photographic lenses have increased significantly. As an important component in the lens, the lens plays a key role in the performance of the entire lens. However, during the lens processing and assembly processes, eccentricity defects often occur, seriously affecting the lens performance. The existing eccentricity detection method fixes the lens or lens group to a rotating platform, and one rotation of the rotating platform completes one eccentricity detection. This detection method cannot display the eccentricity in real time, and the detection process has low efficiency. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a real-time eccentricity detection system to achieve real-time detection of the eccentricity state in view of the deficiencies of the existing technology.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is: a real-time eccentricity detection system, including a light source; the light beam emitted by the light source sequentially passes through a first linear polarizer, a uniaxial crystal, a lens to be measured, and a second linear polarizer to form an interference pattern; the polarization direction of the first linear polarizer is perpendicular to the polarization direction of the second linear polarizer; the light emitting surface of the light source is perpendicular to the center line of the light beam;

[0005] The eccentricity vector e from the center of the outer diameter of the lens to the optical center of the lens is determined by the following formula:

[0006]

[0007] where u1, u2, u3, and u4 are the total light intensities of the four regions of the interference pattern respectively, qn is the vector from the center of the outer diameter of the lens to the centroid of the nth region, and n = 1, 2, 3, 4.

[0008] The present invention can directly and real-time display the eccentricity state without rotating the lens or lens group to be measured, and can detect the optical axis eccentricity of the lens or lens group caused by either tilt or eccentricity at one time, with high eccentricity detection accuracy, effectively reducing the operation cost, improving the detection efficiency, and having a simple structure and low cost.

[0009] qn = (xn, yn) - (x0, y0), where (x0, y0) is the coordinate of the center of the outer diameter of the lens, and (xn, yn) is the coordinate of the centroid of the nth region.

[0010] The calculation formula for the centroid coordinate (x, y) of any region is:

[0011]

[0012] Wherein, m is the number of pixels in the x direction, n is the number of pixels in the y direction, i is the x coordinate of the pixel, j is the y coordinate of the pixel, and g(i, j) is the gray value at the pixel point (i, j).

[0013] In the present invention, the interference pattern is collected by an image acquisition device.

[0014] In the present invention, the center line of the light beam is perpendicular to the horizontal plane.

[0015] In the present invention, the surface of the uniaxial crystal is perpendicular to the center line of the light beam, and the optical axis of the uniaxial crystal is parallel to the center line of the light beam. The uniaxial crystal can move in the vertical direction.

[0016] The first polarizer covers the entire light-emitting surface of the light source.

[0017] The light source is a white light surface light source, and the light source can move up and down in the vertical direction, effectively reducing the system complexity and cost.

[0018] The lens is arranged on the lens carrier table.

[0019] The uniaxial crystal uses a quartz crystal sheet.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention can directly and real-time display the decentration state without rotating the lens or lens group to be measured, and can detect the optical axis decentration amount of the lens or lens group caused by either tilt or decentration at one time, with high decentration detection accuracy, effectively reducing the operation cost, improving the detection efficiency, and having a simple structure and low cost. Description of the Drawings

[0021] Figure 1 It is a schematic layout diagram of the real-time decentration detection system according to an embodiment of the present invention;

[0022] Figure 2 It is a schematic structural diagram of the real-time decentration detection system according to an embodiment of the present invention;

[0023] Figure 3 It is a structural diagram of the lens carrier table displacement mechanism of the real-time decentration detection system according to an embodiment of the present invention;

[0024] Figure 4 It is an interference pattern of the real-time decentration detection system according to an embodiment of the present invention when using a uniaxial crystal thin sheet and having no decentration;

[0025] Figure 5 It is an interference pattern of the real-time decentration detection system according to an embodiment of the present invention when using a uniaxial crystal with a certain thickness and having no decentration;

[0026] Figure 6This is an interference pattern when there is eccentricity in the lens or lens group to be measured by the real-time eccentricity detection system according to the embodiments of the present invention;

[0027] Figure 7 This is a schematic diagram of the calculation method for the eccentricity value and eccentricity direction of the real-time eccentricity detection system and method according to the embodiments of the present invention;

[0028] Figure 1 In the figure: 1 is a light source, 2 is a first linear polarizer, 3 is a uniaxial crystal, 4 is a lens carrier, 5 is a jig, 6 is the lens or lens group to be measured, 7 is a second linear polarizer, and 8 is an image processing device;

[0029] Figure 2 In the figure: A1 is a common white light surface light source; A2 is a linear polarizer, which is fixed on the surface of the plane light source A1; A3 is a quartz crystal; A4 is the lens carrier and the jig; A5 is the lens or lens group to be measured; A6 is a linear polarizer, which is fixed in front of the industrial lens by threads; A7 is an industrial lens, which is fixed to the color industrial camera A8 through an interface; A8 is a color industrial camera, which is connected to the computer through a data cable; A9 is a linear guide;

[0030] Figure 3 In the figure: B1 is a micrometer in the X direction; B2 is a micrometer in the Y direction; B3 is a locking screw in the X direction; B4 is a locking screw in the Y direction. Specific embodiments

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Such as Figure 1As shown in the figure, this embodiment provides a real-time eccentricity detection system and method. From bottom to top, it sequentially includes: a light source 1; a first linear polarizer 2; a uniaxial crystal 3 with its optical axis perpendicular to the surface; a lens carrier 4; a jig 5 for fixing a lens or a lens group to the lens carrier; a lens or lens group 6 to be measured; a second linear polarizer 7 with a polarization direction perpendicular to that of the first linear polarizer; and an image processing device 8 that collects an image passing through the lens or lens group to be measured, calculates the eccentricity value and the eccentricity direction of the lens or lens group to be detected based on the image, and displays them. The image collected by the image processing device 8 is cut into four regions by a central dark cross. The centroid coordinates of the four regions are obtained according to the centroid formulas (1) and (2). The vectors from the center of the lens outer diameter to the centroids of the four regions are calculated respectively through formula (3), and the four centroid vectors are added together through formula (4) to obtain the eccentricity vector from the center of the lens outer diameter to the optical center of the lens, thereby obtaining the eccentricity value and the eccentricity direction.

[0033] In this embodiment, the image collected by the image processing device 8 is cut into four regions by a central dark cross. The centroids of the four regions are obtained according to the centroid formula respectively, and then the vectors from the center of the lens outer diameter to the centroids of the four regions are calculated respectively, and the four vectors are added together to obtain the vector from the center of the lens outer diameter to the optical center of the lens, thereby calculating the eccentricity value and the eccentricity direction. The specific calculation formulas are as follows:

[0034]

[0035]

[0036] qn = (xn, yn) - (x0, y0) (3)

[0037]

[0038] Where m is the number of pixels in the x direction, n is the number of pixels in the y direction, i is the x coordinate of the pixel, j is the y coordinate of the pixel, g(i, j) is the gray value at the pixel point (i, j), (x0, y0) is the coordinate of the center of the lens outer diameter, (xn, yn) is the centroid coordinate of region n, qn is the vector from the center of the lens outer diameter to the centroid of region n, u1 is the total light intensity of region 1, u2 is the total light intensity of region 2, u3 is the total light intensity of region 3, u4 is the total light intensity of region 4, e is the eccentricity vector, the modulus of the vector is the eccentricity value, and its direction is the eccentricity vector direction.

[0039] It has a simple structure, can directly and real-time display the eccentricity state without rotating the lens or lens group to be measured, effectively improves the detection efficiency, reduces the operation cost, and has a high eccentricity detection accuracy.

[0040] The light beam emitted by the light source 1 passes through the first linear polarizer 2 in sequence to become linearly polarized light, and then passes through the uniaxial crystal 3, the lens or lens group 6 to be detected, and the second linear polarizer 7 in sequence to form an interference pattern, which is finally collected by the image acquisition device 8.

[0041] The structure of this embodiment is simple and the cost is low. It can directly and real-time display the eccentricity state without rotating the lens or lens group to be detected.

[0042] The light source 1 can be a parallel light source or an ordinary surface light source. In this embodiment, the light source 1 uses an ordinary white light surface light source. After precise leveling, the light-emitting surface of the light source is perpendicular to the optical axis of the system; the light source 1 is installed on a linear guide rail and can move up and down along the Z axis (as Figure 2 shown). The requirements for the light source in this embodiment are greatly reduced, effectively reducing the system complexity and cost.

[0043] As Figure 2 , in an implementation manner of the present invention, the linear guide rail A9 is vertically arranged. The ordinary white light surface light source A1 is arranged at the front end of the first mounting seat. The rear end of the first mounting seat is arranged on the linear guide rail A9 through rollers and can move on the linear guide rail. The first linear polarizer A2 is attached to the light-emitting surface of the light source. The quartz crystal A3 is arranged at the front end of the second mounting seat. The rear end of the second mounting group is arranged on the linear guide rail A9 through rollers and can move on the linear guide rail. The lens is arranged on the lens carrier A4 and fixed by a jig, and the lens is arranged directly above the quartz crystal. The color industrial camera A8 is fixed at the front end of the third mounting seat. The rear end of the third mounting seat is arranged on the linear guide rail A9 through rollers and can move on the linear guide rail. The industrial lens A7 is fixed on the color industrial camera A8. The second linear polarizer A6 is fixed on the industrial lens by a thread.

[0044] The first linear polarizer 2 uses an optical glass linear polarizer with an extinction ratio greater than 1000:1. It is fixed on the light-emitting surface of the light source 1 and completely covers the entire light-emitting surface of the light source 1; the first linear polarizer 2 can rotate 360 degrees around the optical axis of the system.

[0045] As Figure 3 , the lens carrier 4 can adjust the XY lateral displacement through a micrometer. Its center is hollowed out and does not block the effective diameter part of the lens. It is convenient to adjust the tilt and eccentricity of the lens and improve the operability. Figure 3 In, the X-direction micrometer B1 can adjust the displacement of the lens carrier in the X direction. The X-direction locking screw B3 is used to lock the X-direction micrometer B1. The Y-direction micrometer can adjust the displacement of the lens carrier in the Y direction. The Y-direction locking screw is used to lock the Y-direction micrometer.

[0046] The jig 5 is used to fix the lens or lens group. Its center is hollowed out and does not block the effective diameter part of the lens.

[0047] The uniaxial crystal 3 can be a quartz crystal or a calcite crystal, and its crystal optical axis is perpendicular to the surface and parallel to the system optical axis. Different thicknesses of the uniaxial crystal 3 may result in an interference pattern that contains one or more rings of fringes. Preferably, a thin slice of the uniaxial crystal is used, which forms only one ring of fringes. In this embodiment, the uniaxial crystal 3 is a thin slice of quartz crystal, with a relatively small difference between the refractive indices of the o-ray and the e-ray, making it less likely to produce multiple rings of fringes. After precise leveling, its surface is perpendicular to the system optical axis, and the crystal optical axis is perpendicular to the surface and parallel to the system optical axis. The uniaxial crystal 3 is mounted on a linear guide and can move up and down along the Z-axis.

[0048] This embodiment uses a common material for the uniaxial crystal, which has good transmittance and optical properties in a wide wavelength range, is easy to obtain, and has a low cost. In addition, using a thin slice of quartz crystal can simplify the interference pattern, facilitating the image acquisition device to process and calculate the eccentricity value and the eccentricity direction, thereby improving the eccentricity detection accuracy.

[0049] The second linear polarizer 7 is an optical glass linear polarizer with an extinction ratio greater than 1000:1. It is close to the uniaxial crystal 6 and can move up and down along the Z-axis. It can rotate 360 degrees around the system optical axis, and its polarization direction is perpendicular to the polarization direction of the first linear polarizer, enabling a higher-contrast interference pattern to be obtained.

[0050] The image acquisition device 8 includes an industrial lens, a color industrial camera, and a computer. The industrial lens and the color industrial camera are fixed together through an interface and can move up and down along the Z-axis to ensure a complete interference pattern is obtained. After the camera captures an image, it is transmitted to the computer, and the computer obtains the eccentricity value and the eccentricity direction by processing the interference pattern.

[0051] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications that fall within the scope of the present application.

[0052] Obviously, those skilled in the art can make various changes and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A real-time eccentricity detection system, characterized in that, It includes a light source; the light beam emitted by the light source sequentially passes through a first linear polarizer, a uniaxial crystal, a lens to be measured, and a second linear polarizer to form an interference pattern; the polarization direction of the first linear polarizer is perpendicular to the polarization direction of the second linear polarizer; the light-emitting surface of the light source is perpendicular to the center line of the light beam; The eccentricity vector e from the center of the lens outer diameter to the optical center of the lens is determined by the following formula: where u1, u2, u3, and u4 are the total light intensities of the four regions of the interference pattern respectively, qn is the vector from the center of the lens outer diameter to the centroid of the nth region, and n = 1, 2, 3, 4.

2. The real-time eccentricity detection system according to claim 1, wherein qn = (xn, yn) - (x0, y0), (x0, y0) is the coordinate of the center of the lens outer diameter, and (xn, yn) is the coordinate of the centroid of the nth region.

3. The real-time eccentricity detection system according to claim 2, wherein, The calculation formula for the centroid coordinate (x, y) of any region is: where m is the number of pixels in the x direction, n is the number of pixels in the y direction, i is the x coordinate of the pixel, j is the y coordinate of the pixel, and g(i, j) is the gray value at the pixel point (i, j).

4. The real-time eccentricity detection system according to claim 1, characterized in that, The interference pattern is collected by an image acquisition device.

5. The real-time eccentricity detection system according to any one of claims 1 to 4, characterized in that, The center line of the light beam is perpendicular to the horizontal plane.

6. The real-time eccentricity detection system according to claim 5, characterized in that The surface of the uniaxial crystal is perpendicular to the center line of the light beam, and the optical axis of the uniaxial crystal is parallel to the center line of the light beam, and the uniaxial crystal can move in the vertical direction.

7. The real-time eccentricity detection system according to claim 1, characterized in that, The first polarizer covers the entire light-emitting surface of the light source.

8. The real-time eccentricity detection system according to claim 1, characterized in that The light source is a white light surface source, and the light source can move up and down in the vertical direction.

9. The real-time eccentricity detection system according to claim 1, characterized in that The lens is arranged on a lens carrier platform.

10. The real-time eccentricity detection system according to claim 1, characterized in that, The uniaxial crystal uses a quartz crystal wafer.

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