Lens detection device and method for adjusting micro angle of output image
By adding a position adjustment slide platform to the lens detection device, the translation of the reticle plate supplements the insufficient angle repeatability accuracy of the rotary table, achieving high-precision image centering and reducing costs.
Patent Information
- Application Number
- CN202510889977.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-08-15
AI Technical Summary
When measuring lenses with larger focal lengths, the repetition accuracy of the rotating table is high, resulting in increased costs.
By adding position adjustment, the sliding table drives the reticle movement, so that the rotary table with low repetition accuracy can also achieve high-precision image centering. The adjustment method of the tiny angle of the image output by parallel light tubes is used to supplement the insufficient angle repetition accuracy of the rotary table.
The total cost of the lens detection device is reduced while maintaining high-precision image centering effect.
Smart Images
Figure CN120489515A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of optical detection instruments, and in particular to a lens detection device and a method for adjusting the minute angle of a collimator output image. Background Art
[0002] When domestic and foreign optical lens manufacturers and users communicate about the MTF, focal length, distortion, CRA, LCA and other indicators of optical lenses, the measurement results using the ImageMaster HR equipment of Germany's Trioptics company are the most recognized.
[0003] The optical path of ImageMaster HR is as follows Figure 1 As shown, a uniform backlight 1 illuminates the reticle 2. The reticle 1, bearing bright crosshairs, is located in the focal plane of a collimator 3. The resulting image light enters the lens under test 4 and forms an image on its focal plane 5. The focal plane 5 of the lens under test coincides with the object plane of the objective lens 6. The image of the focal plane is magnified by the objective lens 6 and the tube lens 7 and then formed on the area array image sensor 8. A computer analyzes the image from the area array image sensor to obtain the MTF data for the optical system. Typically, the collimator and the lens under test form a 1 / 5-1 / 100 reduction imaging system, while the objective lens and tube lens form a 50x magnification imaging system. The lens under test has the greatest impact on the image quality of the entire system.
[0004] like Figure 1 As shown in the figure, after the collimator is rotated, when the angle θ between its optical axis and the optical axis of the lens being tested is , the center of the resulting reduced image is located at the image height IH of the focal plane of the lens being tested. The corresponding relationship between angle θ and image height IH is determined by the optical imaging characteristics of the lens being tested. Due to errors in angle θ caused by the repeatability of the rotation stage, the corresponding image height IH will also deviate, resulting in a deviation in the center position of the electronic image output by the image sensor.
[0005] Assume that the focal length of the lens under test is f1, the repeatability of the rotating stage is Δθ, the magnification of the objective lens-tube lens is β, and the uncertainty displacement value Δd of the image position caused by the repeatability error of the rotating stage to the crosshair position, then the following calculation relationship can be obtained:
[0006] Δd=β*f1*tan(Δθ);
[0007] To ensure measurement accuracy, the crosshairs must be centered, meaning Δd is less than the set value. Therefore, when f1 is large, the repeatability of the rotary stage must be higher.
[0008] When measuring lenses with larger focal lengths, related technologies require higher repeatability of the rotating stage, which results in a significant increase in costs. Summary of the Invention
[0009] In view of this, the present application provides a lens detection device and a method for adjusting the small angles of the output image of a parallel light tube. By adding a position adjustment slide to drive the movement of the graticule, a rotating table with low repeatability can also achieve high image centering accuracy, thereby reducing costs.
[0010] In order to achieve the above objectives, this application is implemented through the following technical solutions:
[0011] A lens testing device, characterized by comprising a frame, a placement table provided on the frame for fixing and placing a lens to be tested, an upper mechanism provided above the placement table, and a lower mechanism provided below the placement table;
[0012] The upper mechanism includes a uniform backlight, a reticle, and a collimator, which are arranged in order from top to bottom. The uniform backlight is used to illuminate the reticle, which is engraved with crosshairs. The reticle is located at the focal plane of the collimator. The image light generated by illuminating the reticle enters the lens under test and is reduced to form an image on the focal plane of the lens under test.
[0013] The lower mechanism includes an objective lens, a tube lens, and an area array image sensor arranged in order from top to bottom. The object plane of the objective lens coincides with the focal plane of the lens under test. The image of the focal plane of the lens under test is magnified by the objective lens and the tube lens and then imaged on the area array image sensor.
[0014] A translation mechanism is provided between the lower mechanism and the frame, for driving the objective lens optical axis of the lower mechanism to move to a preset image height position of the lens under test;
[0015] A rotating platform is provided between the upper mechanism and the frame for driving the upper mechanism to rotate relative to the center of the lens under test, wherein during the rotation of the upper mechanism, the center of the reduced crosshair image is brought close to a preset image height position of the lens under test;
[0016] The upper mechanism also includes a position adjustment slide arranged on the collimator for driving the reticle to translate along the direction perpendicular to the optical axis of the collimator and the rotation axis of the rotating stage. By moving the position adjustment slide, the reticle is driven to translate, so that the output image of the collimator produces a slight rotation, so that the center of the reduced crosshair image is closer to the preset image height position of the lens under test, so as to supplement the insufficient angular repeatability accuracy of the rotating stage.
[0017] In some embodiments, the target surface size of the collimator is not less than 1 / 2, and the movement of the position adjustment slide is less than 0.1 mm.
[0018] In some embodiments, the angular repeatability of the rotation stage is ±0.01°, and the repeatability of the position adjustment slide is 0.001 mm.
[0019] The present application also provides a method for adjusting a small angle of an image output by a collimator, which adopts the above-mentioned lens detection device and is characterized in that it includes the following steps:
[0020] ①Place the lens to be tested on the placement table;
[0021] ② Move the optical axis of the objective lens of the lower mechanism to the preset image height position of the lens to be tested;
[0022] ③ Rotate the upper mechanism so that the center of the crosshair pattern is close to the center of the area array image sensor;
[0023] ④ By adjusting the position of the slide, the reticle is translated, causing the collimator output image to rotate slightly, allowing the center of the crosshair pattern to appear in the center of the image of the area array image sensor.
[0024] It can be seen from the above technical solution that this application has at least the following advantages and positive effects:
[0025] This application adds a collimator position adjustment slide. By translating the reticle within a certain range, the collimator output image is rotated slightly, compensating for the lack of angular repeatability of the rotary table. Ordinary precision rotary tables and position adjustment slides are much easier to purchase and much less expensive than those with one or two orders of magnitude higher precision. Therefore, despite the additional components, the overall cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 The optical path diagram of the related technology;
[0027] Figure 2 This is a light path diagram of an embodiment of the present application;
[0028] Figure 3 This is a schematic structural diagram of an embodiment of the present application.
[0029] Explanation of reference numbers: 1. Uniform backlight; 2. Reticle; 3. Collimator; 4. Lens under test; 5. Focal plane of lens under test; 6. Objective lens; 7. Tube lens; 8. Area array image sensor; 9. Rotating stage; 10. Position adjustment slide; 101. Frame. DETAILED DESCRIPTION
[0030] In order to make the purpose, technical solutions and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The terms used in the implementation method section of this application are only used to explain the specific embodiments of this application and are not intended to limit this application.
[0031] See also Figures 2 to 3The embodiment of the present application provides a lens detection device, including a frame 101, a placement table provided on the frame 101 for fixing and placing a lens 4 to be tested, an upper mechanism provided above the placement table, and a lower mechanism provided below the placement table;
[0032] The upper mechanism includes, from top to bottom, a uniform backlight 1, a reticle 2, and a collimator 3. The uniform backlight 1 is used to illuminate the reticle 2, which is engraved with bright crosshairs and is located at the focal plane of the collimator 3. The image light generated by illuminating the reticle 2 enters the lens under test 4 and is then reduced to form an image on the focal plane 5 of the lens under test.
[0033] The lower mechanism includes an objective lens 6, a tube lens 7, and an area array image sensor 8, which are arranged in order from top to bottom. The object plane of the objective lens 6 coincides with the focal plane 5 of the lens under test. The image of the focal plane 5 of the lens under test is magnified by the objective lens 6 and the tube lens 7 and then formed on the area array image sensor 8.
[0034] A translation mechanism is provided between the lower mechanism and the frame 101 for driving the optical axis of the objective lens 6 of the lower mechanism to move to a preset image height position of the lens 4 under test;
[0035] A rotating platform 9 is provided between the upper mechanism and the frame 101 for driving the upper mechanism to rotate relative to the center of the lens 4 under test. During the rotation of the upper mechanism, the center of the reduced crosshair image approaches the preset image height position of the lens 4 under test.
[0036] The upper mechanism also includes a position adjustment slide 10 disposed on the collimator 3 for driving the reticle 2 to translate along a direction perpendicular to the optical axis of the collimator 3 and the rotation axis of the rotating table 9. By moving the position adjustment slide 10 to drive the translation of the reticle 2, the image output by the collimator 3 is rotated by a slight angle, so that the center of the reduced crosshair image is closer to the preset image height position of the lens 4 under test, thereby compensating for the insufficient angular repeatability of the rotating table 9.
[0037] The target surface size of the collimator 3 is not less than 1 / 2, and the movement amount of the position adjustment slide 10 is less than 0.1 mm.
[0038] The working process of the lens detection device includes the following steps:
[0039] ① Place the lens 4 under test on the placement table;
[0040] ② Move the optical axis of the objective lens 6 of the lower mechanism to the preset image height position of the lens 4 to be tested;
[0041] ③ Rotate the upper mechanism so that the center of the crosshair pattern is close to the center of the image of the area array image sensor 8;
[0042] ④ By adjusting the position of the slide 10, the reticle 2 is translated, causing the output image of the collimator 3 to rotate at a slight angle, so that the center of the crosshair pattern appears at the center of the image of the area array image sensor 8.
[0043] Figure 2 As shown, this application builds on the prior art by adding a reticle position adjustment slide. Assuming: the focal length of the lens being measured is f1, the repeatability of the rotation stage is Δθ, the magnification of the objective-tube lens is β, the uncertainty displacement Δd of the image position caused by the repeatability error of the rotation stage on the crosshair position, the focal length of the collimator is f2, and the repeatability of the position adjustment slide is Δd3, then the following calculation relationship is obtained:
[0044] When using a rotating stage, Δd1=β*f1*tan(Δθ);
[0045] When using a position adjustment slide, Δd2 = β*f1*Δd3 / f2;
[0046] Comparing the two, Δd1 / Δd2=tan(Δθ) / Δd3*f2;
[0047] Typically, the angular repeatability of an industrial-grade rotation stage is Δθ = ±0.01°, making it cost-effective for use in industrial equipment. The repeatability of an industrial-grade position adjustment slide is 0.001mm. The focal lengths of the collimators in the ImageMaser HR are 50mm and 300mm, respectively. Using the accuracies of the industrial-grade rotation stage and position adjustment slide, the following calculation is performed:
[0048] f2=50mm: Δd1 / Δd2=tan(0.01°) / 0.001*50=8.73;
[0049] f2=300mm: Δd1 / Δd2=tan(0.01°) / 0.001*300=52.4;
[0050] When using an industrial-grade rotary stage, the centering accuracy can be increased to 8.73 times or 52.4 times by adding an industrial-grade position adjustment slide to move the graticule.
[0051] Normally, the target surface size of the collimator is not less than 1 / 2 inch. If the movement of the position adjustment slide is less than 0.1 mm, it will not affect the image quality of the collimator output image.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, rather than to limit them. Although the embodiments of the present application have been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A lens detection device, characterized in that: It comprises a frame (101), a placement platform arranged on the frame (101) for fixing and placing a lens (4) to be tested, an upper mechanism arranged above the placement platform, and a lower mechanism arranged below the placement platform; The upper mechanism comprises a uniform backlight (1), a reticle (2) and a collimator (3) arranged in sequence from top to bottom, wherein the uniform backlight (1) is used to illuminate the reticle (2), a crosshair bright line is engraved on the reticle (2), and the reticle (2) is located at the focal plane of the collimator (3). After the image light generated by illuminating the reticle (2) enters the lens under test (4), it is reduced and imaged on the focal plane (5) of the lens under test; The lower mechanism comprises an objective lens (6), a tube lens (7), and an area array image sensor (8) arranged in sequence from top to bottom; the object plane of the objective lens (6) coincides with the focal plane (5) of the lens under test; and the image of the focal plane (5) of the lens under test is magnified by the objective lens (6) and the tube lens (7) and then imaged on the area array image sensor (8); A translation mechanism is provided between the lower mechanism and the frame (101) for driving the optical axis of the objective lens (6) of the lower mechanism to move to a preset image height position of the lens (4) to be measured; A rotating platform (9) is provided between the upper mechanism and the frame (101) for driving the upper mechanism to rotate relative to the center of the lens (4) to be tested. During the rotation of the upper mechanism, the center of the reduced crosshair image is brought close to a preset image height position of the lens (4) to be tested. The upper mechanism further comprises a position adjustment slide (10) arranged on the collimator (3) for driving the grating plate (2) to move in a translational direction perpendicular to the optical axis of the collimator (3) and the rotation axis of the rotating platform (9). By moving the position adjustment slide (10) to drive the translation of the grating plate (2), the image output by the collimator (3) is rotated at a slight angle, so that the center of the reduced crosshair image is closer to the preset image height position of the measured lens (4), thereby compensating for the lack of angular repeatability accuracy of the rotating platform (9).
2. The lens detection device according to claim 1, characterized in that: The target surface size of the collimator (3) is not less than 1 / 2, and the movement amount of the position adjustment slide (10) is less than 0.1 mm.
3. The lens detection device according to claim 1, wherein: The angular repeatability of the rotating table (9) is ±0.01°, and the repeatability of the position adjustment slide (10) is 0.001 mm.
4. A method for adjusting the micro-angle of a collimator output image, using the lens detection device according to any one of claims 1 to 3, characterized in that: The following steps are involved: ① Place the lens to be tested (4) on the placement table; ② moving the optical axis of the objective lens (6) of the lower mechanism to a preset image height position of the lens (4) to be measured; ③ Rotate the upper mechanism so that the center of the crosshair pattern is close to the center of the image of the area array image sensor (8); ④ By adjusting the position of the slide (10), the graticule (2) is moved in translation, so that the output image of the collimator (3) is rotated at a small angle, so that the center of the crosshair pattern appears in the center of the image of the area array image sensor (8).