Optical lens centering and positioning device and method based on a multi-focal annular lens

Abstract

The application discloses a kind of optical lens centering positioning device and method based on multi-focus ring zone lens, the device is by autocollimator, multi-focus ring zone lens, precision five-dimensional adjusting frame, lens group to be measured, mirror seat, leveling centering device, air bearing, displacement sensor, marble frame, image display system, centering positioning measurement analysis system composition, mirror seat is installed on the centering leveling device of air bearing, and through displacement sensor to the center axis of mirror seat and the center axis of air bearing coincide, the spherical center of lens upper surface is located in the focal point of multi-focus ring zone lens, without adjusting the position of multi-focus ring zone lens, the high-precision lens can be quickly centered, and the assembling and adjusting time of lens is greatly reduced;The edge spread function of cross differentiation silk is analyzed by image processing and display system, so as to calculate the axial assembly error of lens, the application solves the problems of low optical lens centering positioning precision and low assembly efficiency.

Description

Technical Field

[0001] This invention relates to the field of optical inspection technology, and in particular to an optical lens centering and positioning device and method based on a multifocal ring lens. Background Technology

[0002] An optical lens is an optical element with two curved (or flat) boundaries, capable of refracting and focusing light. An optical lens group is a collection of two or more optical lenses. By combining different lenses, specific optical functions and performances are achieved. They are commonly used in optical systems such as industrial cameras, telescopes, microscopes, and lighting systems. In the design, assembly, and actual use, the centering of the optical lens group (the centers of all lenses being on a straight line) is crucial. Otherwise, it will affect the correct passage of light through the lens group and its focusing onto the imaging plane, thus affecting the performance and image quality of the optical system.

[0003] The commonly used centering method is to use a centering instrument. The light emitted by the light source is collimated by the collimation system to produce parallel light. Then, the light is converged by a single-focusing lens. When the focal point of the focused light coincides with the center of the lens surface, a portion of the light is reflected back along the original path. By observing whether the center position of the light spot changes with the rotation of the lens, it can be determined whether the assembly is correct. However, in actual assembly and adjustment, it is necessary to repeatedly replace the focusing lens or adjust the vertical distance of the lens and continuously adjust the position of the lens to ensure a precise focus. This adjustment process is time-consuming and tedious, requires a high level of skill from the operator, and is prone to introducing errors. Summary of the Invention

[0004] The purpose of this invention is to provide an optical lens centering and positioning device and method based on a multifocal annular lens. The multifocal annular lens in the device of this invention has multiple focal points, eliminating the need for repeated adjustment of the lens position, and thus enabling rapid and accurate detection of the imaging of multiple focal points, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An optical lens centering and positioning device based on a multifocal ring lens specifically includes:

[0007] The marble frame has an autocollimator installed at the top, a precision five-dimensional adjustment frame installed in the middle, a multi-focal ring lens installed inside the precision five-dimensional adjustment frame, and an air bearing installed at the bottom.

[0008] The upper part of the air bearing is equipped with a leveling and self-aligning device, which is used to adjust the central axis of the mirror mount and the central axis of the air bearing to be coaxial;

[0009] The top of the leveling and centering device is equipped with a mirror mount, which is used to mount the lens group to be tested;

[0010] It also includes an image display system and a centering and positioning measurement and analysis system. The image display system is connected to the autocollimator, and the image display system is connected to the centering and positioning measurement and analysis system.

[0011] It also includes a displacement sensor for measuring the coaxiality of the mirror mount and the air bearing, and inputting the measurement results into the centering and positioning measurement and analysis system.

[0012] Preferably, the autocollimator is used to output a parallel collimated laser beam and acquire a reflected image, and consists of a light source, a focusing lens, a cross reticle, a beam splitter, a collimating lens, and an image acquisition module;

[0013] Among them: the light source is used to emit a diverging laser beam;

[0014] A focusing lens is used to converge the light beam emitted by the light source onto the reticle, thereby achieving uniform illumination of the reticle.

[0015] The surface of the reticle has two short, perpendicular horizontal lines engraved on it, located at the focal length of the focusing lens, used to form the crosshair image.

[0016] The beam splitter is used to separate the emitted light rays and the reflected light rays into two paths. The light rays emitted through the crosshair remain unchanged along their original direction, while the reflected light rays propagate perpendicularly to the image acquisition module.

[0017] A collimating lens is used to collimate the light emitted through the reticle into horizontal light for centering;

[0018] The image acquisition module uses an image sensor to acquire crosshair reflection images and outputs the image data to the given positioning measurement and analysis system.

[0019] Preferably, in the multifocal annular lens, each annular band has a different focal length, and the focal points of different annular bands are distributed along the optical axis of the multifocal annular lens. The position of the focal point of the multifocal annular lens is determined by the position of the center of the sphere of the optical lens in the lens group under test.

[0020] Preferably, the air bearing is a hydrostatic air bearing, which can rotate the mirror mount and the lens group under test in the horizontal direction to provide high rotational accuracy for the centering system.

[0021] Preferably, the upper surface of the multifocal annular lens is a standard spherical and aspherical surface, and the lower surface is an annular surface. The annular surface is a discontinuous annular Fresnel surface or is composed of continuous non-guided curved surfaces.

[0022] Preferably, the multiple focal points of the multifocal ring lens are located, from bottom to top, at the curvature centers of the upper surfaces of the lens group under test from bottom to top.

[0023] A method for centering and positioning an optical lens based on a multifocal ring lens includes the following steps:

[0024] S1. Install the mirror mount onto the leveling and self-aligning device, and use the displacement sensor to measure and make the mirror mount coaxial with the air bearing;

[0025] S2. Place the first optical lens to be installed in the lens group under test on the lens mount, adjust the precision five-dimensional adjustment frame so that the focal point in the multifocal ring lens coincides with the center of the sphere on the front surface of the optical lens, and rotate the air bearing to analyze the movement trajectory of the crosshair. Adjust the position of the optical lens to be installed according to the movement trajectory until the centering error in the centering and positioning measurement and analysis system is minimized.

[0026] S3. Install the next lens in the lens group to be tested and repeat S2. At this time, the optical lens installation and adjustment does not require adjustment of the multifocal ring lens. The reflected image of the crosshairs can be directly acquired in the image acquisition module. Adjust the position of the installed optical lens according to the motion trajectory until the centering error is minimized in the centering and positioning measurement and analysis system.

[0027] S4. By performing a Fourier transform on the edge diffusion function of the crosshair image, the contrast value is obtained, and the axial positioning error of the optical lens is calculated.

[0028] The device of this invention has a simple structure and is easy to integrate. It requires minimal modification and adjustment to the system, only requiring the replacement of the focusing lens of the existing centering device with a multifocal ring lens. This solves the problem of repeatedly adjusting the position of the focusing lens during centering and allows for simultaneous detection of images from multiple focal points, providing an effective and convenient solution for the field of optical centering. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an optical lens centering and positioning device system based on a multifocal ring lens proposed in this invention.

[0030] Figure 2 This is a schematic diagram of the internal structure of the autocollimator proposed in this invention.

[0031] Figure 3 This is a side view of the multifocal ring lens proposed in this invention.

[0032] Figure label:

[0033] 1. Autocollimator; 2. Multifocal ring lens; 3. Precision five-dimensional adjustment frame; 4. Lens group to be tested; 5. Lens mount; 6. Leveling and centering device; 7. Air bearing; 8. Displacement sensor; 9. Marble frame; 10. Image display system; 11. Centering and positioning measurement and analysis system; 12. Light source; 13. Focusing lens; 14. Crosshair reticle; 15. Beam splitter prism; 16. Collimating lens; 17. Image acquisition module. Detailed Implementation

[0034] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0035] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection" and "installation" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, "connection" can be a direct connection or an indirect connection through an intermediate medium. "Fixed" means that the devices are connected to each other and their relative positional relationship remains unchanged after the connection. The directional terms mentioned in the embodiments of the present invention, such as "inner," "outer," "top," and "bottom," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0036] In this embodiment of the invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0037] An optical lens centering and positioning device based on a multifocal ring lens specifically includes an autocollimator 1, a multifocal ring lens 2, a precision five-dimensional adjustment frame 3, a lens group to be tested 4, a lens base 5, a leveling and centering device 6, an air bearing 7, a displacement sensor 8, a marble frame 9, an image display system 10, and a centering and positioning measurement and analysis system 11.

[0038] The autocollimator 1 is used to output a parallel collimated laser beam and acquire the reflected image. It consists of a light source 12, a focusing lens 13, a crosshair reticle 14, a beam splitter 15, a collimating lens 16, and an image acquisition module 17. Specifically: the light source 12 emits a diverging laser beam; the focusing lens 13 converges the beam emitted by the light source 12 onto the crosshair reticle 14 to achieve uniform illumination of the crosshair reticle 14; the crosshair reticle 14 has two mutually perpendicular short horizontal lines engraved on its surface, located at the focal length of the focusing lens 13, used to form a crosshair image; the beam splitter 15 separates the emitted light and the reflected light into two paths, the light emitted through the crosshair reticle 14 remains unchanged along its original direction, and the reflected light propagates perpendicularly to the image acquisition module 17; the collimating lens 16 collimates the light emitted through the crosshair reticle 14 into a horizontal beam for centering; and the image acquisition module 17 uses an image sensor to acquire the crosshair reflected image and outputs the image data to the centering positioning measurement and analysis system 11.

[0039] The multifocal annular lens 2 has each annular band having a different focal length, i.e., having multiple annular band focal points at different positions; the focal points of different annular bands are distributed along the optical axis of the multifocal annular lens 2; the position of the focal point of the multifocal annular lens 2 is determined by the position of the center of the sphere of the optical lens in the lens group 4 under test.

[0040] The precision five-dimensional adjustment frame 3 is used to adjust the position of the multifocal ring lens 2 so that the focal point of the multifocal ring lens 2 coincides with the center of the sphere of the lens to be tested in the lens group 4.

[0041] The lens group 4 under test is used to reflect the beam back to the autocollimator 1.

[0042] The lens mount 5 is used to fix and adjust the position of the lens group 4 to be tested.

[0043] The leveling and self-aligning device 6 is installed on the air bearing 7 and is used to adjust the central axis of the mirror base 5 and the central axis of the air bearing 7 to be coaxial.

[0044] The air bearing 7 is a hydrostatic air bearing, which is fixed to the mirror base 5. It can rotate the mirror base 5 and the lens group 4 under test in the horizontal direction to provide high rotational accuracy for the centering system.

[0045] Displacement sensor 8 is used to measure the coaxiality of the mirror mount and the air bearing, and inputs the measurement results into the centering and positioning measurement and analysis system 11.

[0046] The marble frame 9 is used to fix the autocollimator 1, the precision five-dimensional adjustment frame 3, and the air bearing 7, and to ensure that the optical axis of the autocollimator 1 coincides with the rotation axis of the air bearing 7.

[0047] The image display system 10 is used to receive the reflected image input from the autocollimator 1 and display the motion trajectory of the crosshair reflection image.

[0048] The centering and positioning measurement and analysis system 11 shown receives data from the displacement sensor 8 and the image display system 10. It then uses an image recognition algorithm to analyze the eccentricity error and tilt error of the crosshair movement trajectory and gives the centering accuracy. At the same time, it calculates the axial assembly error of the optical lens by performing a Fourier transform on the edge diffusion function of the crosshair image to obtain the contrast value.

[0049] In this embodiment, the parallel light beam is converged at the center of the front surface of the optical lens by the multifocal ring lens 2. The light beam is reflected back to the collimator 1 by the optical lens of the lens group under test 4 and imaged on the image acquisition module 17 by the beam splitter prism 15.

[0050] In this embodiment, the upper surface of the multifocal annular lens 2 is a standard spherical and aspherical surface, and the lower surface can be an annular surface; the annular surface can be a discontinuous annular Fresnel surface, or it can be composed of a continuous non-differentiable curved surface.

[0051] In this embodiment, the multiple focal points of the multifocal ring lens 2 are located from bottom to top at the curvature centers of the upper surfaces of the lens group 4 to be tested, from bottom to top.

[0052] This invention also designs an optical lens centering and positioning method based on a multifocal ring lens. Figure 3 This is a side view of the multifocal annular lens proposed in this invention. Taking the multifocal annular lens 2 with N=7 Fresnel zones on its Fresnel surface as an example, the focal length of the innermost zone (1st zone) is f1, the focal length of the second and third zones (second innermost zone) is f2, the focal length of the fourth and fifth zones (second outermost zone) is f3, and the focal length of the sixth and seventh zones (outermost zone) is f4. The lens group 4 under test consists of four lenses. In the design, the center of curvature of the upper surface of each lens is located, from bottom to top, at the centers of curvature of f1, f2, f3, and f4, respectively.

[0053] Install the mirror mount 5 onto the leveling and self-aligning device 6, and use the displacement sensor 8 to measure and make the mirror mount 5 coaxial with the air bearing 7;

[0054] Place the first optical lens (focal length f1) to be installed in the lens group 4 under test on the lens mount 5, adjust the precision five-dimensional adjustment frame 3 so that the focal point in the multifocal ring lens 2 coincides with the center of the sphere on the front surface of the optical lens; and rotate the air bearing 7 to analyze the movement trajectory of the crosshair, and adjust the position of the optical lens to be installed according to the movement trajectory until the centering error in the centering and positioning measurement and analysis system 11 is minimized.

[0055] Place the second optical lens (focal length f2) to be installed in the lens group 4 under test on the lens mount 5. At this time, the optical lens installation and adjustment does not require adjustment of the multifocal ring lens 2. Rotate the air bearing 7 to analyze the movement trajectory of the crosshair, and adjust the position of the optical lens to be installed according to the movement trajectory until the centering error is minimized in the centering and positioning measurement and analysis system 11.

[0056] Place the third optical lens (focal length f3) to be installed in the lens group 4 under test onto the lens mount 5. At this time, the optical lens installation and adjustment do not require adjustment of the multifocal ring lens 2. Rotate the air bearing 7 to analyze the movement trajectory of the crosshair, and adjust the position of the optical lens to be installed according to the movement trajectory until the centering error is minimized in the centering and positioning measurement and analysis system 11.

[0057] Place the fourth optical lens (focal length f4) to be installed in the lens group 4 on the lens mount 5. At this time, the optical lens installation does not require adjustment of the multifocal ring lens 2. Rotate the air bearing 7 to analyze the movement trajectory of the crosshair, and adjust the position of the optical lens to be installed according to the movement trajectory until the centering error is minimized in the centering and positioning measurement and analysis system 11.

[0058] Finally, by performing a Fourier transform on the edge spread function of the crosshair image to obtain the contrast value, the axial positioning error of the optical lens is calculated, thus completing the lens centering process.

[0059] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. In the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An optical lens centering and positioning device based on a multifocal ring lens, characterized in that, Specifically, it includes: Marble frame (9), autocollimator (1) is installed on the upper part of marble frame (9), precision five-dimensional adjustment frame (3) is installed in the middle part of marble frame (9), multi-focal ring lens (2) is installed inside precision five-dimensional adjustment frame (3), and air bearing (7) is installed on the lower part of marble frame (9). A leveling and self-aligning device (6) is installed on the upper part of the air bearing (7) to adjust the central axis of the mirror mount (5) and the central axis of the air bearing (7) to be coaxial. The top of the leveling and centering device (6) is equipped with a mirror mount (5), which is used to mount the lens group (4) to be tested. It also includes an image display system (10) and a centering and positioning measurement and analysis system (11). The image display system (10) is connected to the autocollimator (1), and the image display system (10) is connected to the centering and positioning measurement and analysis system (11). It also includes a displacement sensor (8) for measuring the coaxiality of the mirror mount (5) and the air bearing (7) and inputting the measurement results into the centering and positioning measurement and analysis system (11).

2. The optical lens centering and positioning device based on a multifocal ring lens according to claim 1, characterized in that, The self-collimator (1) is used to output a parallel collimated laser beam and acquire a reflected image. It consists of a light source (12), a focusing lens (13), a cross reticle (14), a beam splitter (15), a collimating lens (16), and an image acquisition module (17). Wherein: the light source (12) is used to emit a diverging laser beam; The focusing lens (13) is used to converge the light beam emitted by the light source (12) onto the cross reticle (14) to achieve uniform illumination of the cross reticle (14); The surface of the crosshair reticle (14) is engraved with two short horizontal lines that are perpendicular to each other and located at the focal length of the focusing lens (13) to form a crosshair image. The beam splitter (15) is used to separate the emitted light and the reflected light into two paths. The light emitted by the cross reticle (14) remains unchanged along its original direction, while the reflected light propagates vertically to the image acquisition module (17). The collimating lens (16) is used to collimate the light emitted through the crosshair (14) into a horizontal light for centering; The image acquisition module (17) uses an image sensor to acquire the crosshair reflection image and outputs the image data to the given positioning measurement and analysis system (11).

3. The optical lens centering and positioning device based on a multifocal ring lens according to claim 1, characterized in that, The multifocal annular lens (2) has a different focal length for each annular band. The focal points of different annular bands are distributed along the optical axis of the multifocal annular lens (2). The position of the focal point of the multifocal annular lens (2) is determined by the position of the center of the optical lens in the lens group (4) to be tested.

4. The optical lens centering and positioning device based on a multifocal ring lens according to claim 1, characterized in that, The air bearing (7) is a hydrostatic air bearing that can rotate the mirror mount (5) and the lens group (4) under test in the horizontal direction, providing high rotational accuracy for the centering system.

5. The optical lens centering and positioning device based on a multifocal ring lens according to claim 3, characterized in that, The upper surface of the multifocal annular lens (2) is a standard spherical and aspherical surface, and the lower surface is an annular surface. The annular surface is a discontinuous annular Fresnel surface or is composed of a continuous non-guided surface.

6. The optical lens centering and positioning device based on a multifocal ring lens according to claim 3, characterized in that, The multiple focal points of the multifocal ring lens (2) are located from bottom to top at the curvature centers of the upper surface of the lens group (4) from bottom to top.

7. A method for centering and positioning optical lenses based on multifocal annular lenses, characterized in that, Includes the following steps: S1. Install the mirror mount (5) onto the leveling and self-aligning device (6), and measure the distance using the displacement sensor (8) to make the mirror mount (5) coaxial with the air bearing (7); S2. Place the first optical lens to be installed in the lens group (4) on the lens mount (5), adjust the precision five-dimensional adjustment frame (3) to make the focal point in the multifocal ring lens (2) coincide with the center of the front surface of the optical lens, and rotate the air bearing (7) to analyze the movement trajectory of the crosshair. Adjust the position of the optical lens to be installed according to the movement trajectory until the centering error is minimized in the centering and positioning measurement and analysis system (11). S3. Install the next lens of the lens group to be tested (4) and repeat S2. At this time, the optical lens installation does not need to adjust the multifocal ring lens (2). The reflected image of the crosshair can be directly acquired in the image acquisition module (17). Adjust the position of the installed optical lens according to the motion trajectory until the centering error is minimized in the centering positioning measurement and analysis system (11). S4. By performing a Fourier transform on the edge diffusion function of the crosshair image, the contrast value is obtained, and the axial positioning error of the optical lens is calculated.

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