Method for detecting optical axis deviation in camera lens assembly
By taking the screen body of the design pattern and converting it into a heat map, and combining with the tool adjustment, the optical axis deviation of the industrial camera lens is accurately judged, which solves the expensive and error detection problem in the existing technology, and achieves high-precision optical axis deviation Shift detection.
Patent Information
- Application Number
- CN202411263885.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-10
- Publication Date
- 2024-12-27
AI Technical Summary
In the prior art, when detecting the optical axis deviation of industrial cameras and industrial lenses, the eccentricity measurement method is expensive and the measurement data has large errors, which cannot meet the needs of high-precision imaging.
By using the camera and lens combination to test, the screen with the design pattern is shot, and converted into a thermal map, determine whether there is an offset in the optical axis, adjust the tilt angle of the fixture, shoot successively, and compare the uniformity of the thermal map, accurately judge the optical axis deviation. Move direction and angle, reduce costs and improve measurement accuracy.
It realizes the accurate judgment of the optical axis offset of the camera lens without using expensive eccentricity, reduces detection costs, improves the accuracy of measurement data, and solves the problems of high prices and large errors in the prior art.
Smart Images
Figure CN119198008A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of machine vision imaging, and in particular to a method for detecting optical axis offset of a camera lens assembly. Background Art
[0002] At present, industrial cameras and industrial lenses in machine vision are used as high-precision imaging equipment to detect defects in DUT (Device Under Test). Therefore, the MTF (modulation transfer function) of visual imaging is very high, and it is necessary to ensure that the imaging screen matched with the detection equipment has extremely high uniformity. Whether the optical axis of the industrial camera and industrial lens is offset will affect the uniformity of the imaging screen. Therefore, when performing defect detection, it is necessary to measure whether the optical axis is offset.
[0003] In the related art, when measuring whether the optical axis of an industrial camera or an industrial lens is offset, an eccentricity meter is generally used for measurement. However, the eccentricity meter is expensive and the measurement data has a large error.
[0004] Therefore, it is necessary to design a new method for detecting the optical axis offset of the camera lens assembly to overcome the above problems. Summary of the invention
[0005] The present application provides a method for detecting the offset of the optical axis of a camera lens assembly, which can solve the technical problem in the related art that the method of using an eccentric meter to measure whether the optical axis is offset is expensive and the measurement data has errors.
[0006] In a first aspect, an embodiment of the present application provides a method for detecting optical axis offset of a camera lens assembly, which comprises the following steps:
[0007] A screen displaying a design pattern is photographed using a combination of a camera and a lens to be tested to obtain a test pattern, the test pattern is converted into a thermal map, and based on the thermal map, it is determined whether the optical axis of the combination of the camera and the lens to be tested is offset.
[0008] In combination with the first aspect, in one embodiment, before using the combination of the camera to be tested and the lens to photograph the screen displaying the design pattern to obtain the test image, the method further includes:
[0009] Adjust the fixture connected to the camera to keep the level between the fixture and the screen below the preset angle value.
[0010] In combination with the first aspect, in one implementation, judging whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map includes:
[0011] Determine whether the modulation transfer function value of the design pattern in the thermal map satisfies the modulation transfer function trend of the lens theory;
[0012] If so, the optical axis does not have an offset; otherwise, the optical axis does have an offset.
[0013] In combination with the first aspect, in one implementation, determining whether the modulation transfer function value of the design pattern in the heat map satisfies the modulation transfer function trend of the lens theory includes:
[0014] If the MTF value in the center area of the heat map is higher than that in the surrounding areas, and the MTF values in the heat map are symmetrically distributed, the MTF value of the design pattern in the heat map satisfies the MTF trend of the lens theory.
[0015] In combination with the first aspect, in one embodiment, after determining whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map, the method further includes:
[0016] If it is determined that the optical axis of the combination of the camera and lens to be tested is offset, the tilt angle of the fixture is adjusted, and the combination of the camera and lens to be tested is used to shoot a screen displaying a design pattern to obtain an adjustment map, which is converted into a heat map and the tilt direction of the optical axis is determined based on the heat map.
[0017] In combination with the first aspect, in one embodiment, the tilt angle of the adjustment fixture is adjusted, and a screen displaying a design pattern is photographed using a combination of a camera to be tested and a lens to obtain an adjustment map, and the adjustment map is converted into a thermal map and the tilt direction of the optical axis is determined based on the thermal map, including:
[0018] Adjusting a fixture connected to the camera so that the fixture is tilted relative to the screen in a first direction at a preset angle, and photographing the screen using a combination of the camera to be tested and the lens to obtain an adjustment diagram;
[0019] Convert the adjustment image into a heat map, and compare the uniformity of the heat map of the adjustment image with the heat map of the test image;
[0020] If the thermal map of the adjustment image is more uniform than the thermal map of the test image, the tilt direction of the optical axis is opposite to the first direction; if the thermal map of the test image is more uniform than the thermal map of the adjustment image, the tilt direction of the optical axis is the same as the first direction.
[0021] In combination with the first aspect, in one embodiment, after determining whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map, the method further includes:
[0022] If it is determined that the optical axis of the combination of the camera and the lens to be tested is offset, the jig connected to the camera is adjusted so that the jig is gradually tilted in the first direction relative to the screen by a preset angle, and the screen is photographed using the combination of the camera and the lens to be tested after each tilt by the preset angle to obtain multiple adjustment images;
[0023] Convert multiple adjustment maps into thermal maps, and find the thermal map that is closest to the trend of the theoretical modulation transfer function of the lens. The tilt angle corresponding to the thermal map that is closest to the trend of the theoretical modulation transfer function of the lens is the optical axis tilt angle with the best imaging uniformity.
[0024] In combination with the first aspect, in one embodiment, the method of using the combination of the camera and the lens to be tested to shoot a screen displaying a design pattern to obtain a test pattern, converting the test pattern into a thermal map, and determining whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map includes:
[0025] Using a combination of a camera and a lens to be tested to shoot a screen displaying a design pattern, to obtain a first test image;
[0026] After changing the back focal length of the lens, the combination of the camera to be tested and the lens is used again to shoot the screen displaying the design pattern to obtain a second test image;
[0027] Converting the first test image and the second test image into thermal maps, and comparing whether the thermal maps of the first test image and the second test image are the same;
[0028] If they are not the same, it means that the optical axis of the combination of the camera and lens to be tested is offset.
[0029] In combination with the first aspect, in one implementation, the design pattern is a plurality of blade blocks displayed in the screen body, and the plurality of blade blocks are evenly arranged into a plurality of rows and a plurality of columns.
[0030] In combination with the first aspect, in one embodiment, before using the combination of the camera to be tested and the lens to photograph the screen displaying the design pattern to obtain the test image, the method further includes:
[0031] Focus the combination of the camera and lens to be tested. When the image is magnified and a preset number of transition pixels appear, the focus is successful.
[0032] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:
[0033] A test image can be obtained by photographing a screen with a designed pattern. Based on the thermal map of the test image, it is possible to determine whether the optical axis is offset. There is no need to use an expensive eccentricity meter for measurement and judgment, which can greatly reduce costs. The test image measurement data obtained by photographing with a camera and a lens is accurate, and it is possible to accurately determine whether the optical axis is offset. This solves the technical problem in the related art that the method of using an eccentricity meter to measure whether the optical axis is offset is expensive and the measurement data has errors. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0035] Figure 1 A flow chart of a method for detecting optical axis offset of a camera lens assembly provided in an embodiment of the present application;
[0036] Figure 2 A flow chart of another method for detecting optical axis offset of camera lens assembly provided in an embodiment of the present application;
[0037] Figure 3 A flowchart of another method for detecting optical axis offset of a camera lens assembly provided in an embodiment of the present application;
[0038] Figure 4 The theoretical modulation transfer function trend of the lens provided in the embodiment of the present application;
[0039] Figure 5 A schematic diagram of a test diagram provided in an embodiment of the present application;
[0040] Figure 6 The thermal map obtained when the horizontality is 0.02° provided in the embodiment of the present application;
[0041] Figure 7 for Figure 6 Comparison chart of MTF values in the first and eleventh columns;
[0042] Figure 8 This is a thermal diagram obtained when the fixture provided in the embodiment of the present application is tilted 1° to the upper right;
[0043] Fig. 9 for Figure 8 Comparison chart of MTF values in the first and eleventh columns;
[0044] Fig.10 This is a thermal diagram obtained when the fixture provided in the embodiment of the present application is tilted 1° to the upper left;
[0045] Fig.11 for Fig.10 Comparison chart of MTF values in the first and eleventh columns;
[0046] Fig.12 A thermal map of a first test image taken at 0° by the lens provided in an embodiment of the present application;
[0047] Fig.13 A thermal map of a second test image taken at 180° by the lens provided in an embodiment of the present application;
[0048] Fig.14 for Fig.12 The three-dimensional graph displayed in matlab;
[0049] Fig.15 for Fig.13 The three-dimensional graph displayed in Matlab. DETAILED DESCRIPTION
[0050] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0051] The embodiment of the present application provides a method for detecting the offset of the optical axis of a camera lens assembly, which can solve the technical problem in the related art that the method of using an eccentric meter to measure whether the optical axis is offset is expensive and the measurement data has errors.
[0052] See also Figure 1 As shown, the embodiment of the present application provides a method for detecting the optical axis offset of a camera lens assembly, which comprises the following steps:
[0053] S1: Use the combination of the camera and the lens to be tested to shoot a screen displaying a design pattern to obtain a test pattern, convert the test pattern into a thermal map, and determine whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map. In this step, when shooting the test pattern, shooting is performed under darkroom conditions.
[0054] In this embodiment, the lens is installed at the lower end of the camera to form a combination of the camera and the lens to be tested, and the lens and the camera are located directly above the screen. A specially made design pattern is displayed on the screen to test the MTF, where the screen can be an iPad. The MTF (modulation transfer function) value and overall trend of the design pattern are shown in the heat map. The higher the MTF, the clearer the image. Figure 6 In the heat map, yellow represents good imaging, and blue represents poor imaging. The trend of the lens theoretical modulation transfer function is as follows: Figure 4 As shown, the center is high, and the MTF gradually decreases as it extends outward.
[0055] In this embodiment, a test image with a design pattern can be obtained by photographing a screen with a design pattern ( Figure 5 As shown), convert the test image into a heat map ( Figure 6 As shown in the figure, the MTF value and the overall trend of the design pattern are reflected in the heat map. Based on the heat map of the test image, it is possible to determine whether the optical axis is offset, without the need to use an expensive eccentric meter for measurement and judgment, which can greatly reduce costs. In addition, the use of an eccentric meter in the related art can only obtain the offset result of a single lens, and cannot determine the imaging situation of the camera lens combination. In this embodiment, the method of obtaining the test image and the heat map by shooting with a camera and a lens can obtain the offset result of the entire combination of the camera and the lens to be tested. The measurement data is more accurate, and it is possible to accurately determine whether the optical axis is offset, which solves the technical problem that the method of using an eccentric meter to measure whether the optical axis is offset in the related art is expensive and the measurement data has errors.
[0056] Furthermore, in one embodiment, before using the combination of the camera to be tested and the lens to photograph the screen displaying the design pattern to obtain the test image, the method may further include: adjusting the fixture connected to the camera so that the horizontality between the fixture and the screen is maintained below a preset angle value ( Figure 2 shown).
[0057] In this embodiment, a multi-axis adjustment platform can be used to install the camera, lens and screen. A jig is installed in the multi-axis adjustment platform. The jig has a mounting plane. The lens is mounted on the camera, and the camera is mounted on the mounting plane. When comparing the levelness of the jig and the screen, a level meter is directly used to measure the levelness of the mounting plane and the screen surface to keep the levelness below 0.02° (as close to 0° as possible). In this embodiment, since the jig and the screen have been adjusted to a sufficient level before shooting the test image, the screen can be directly shot once in this state to obtain a test image. The thermal map of the test image can directly reflect whether the optical axis is offset, and it is not necessary to shoot a second time to determine whether the optical axis is offset.
[0058] Preferably, the design pattern is a plurality of blade blocks ( Figure 5 The plurality of blade blocks are evenly arranged in multiple rows and columns. Figure 5As shown in the figure, 9 rows and 11 columns of blade blocks are designed in the screen, and a total of 9*11 blade blocks are obtained. Each blade block is designed with a specific tilt angle. The multiple rows and columns of blade blocks displayed in the screen will be displayed in the test image after shooting the test image. When the test image is converted into a thermal map, each blade block will correspond to an MTF value, see Figure 6 The design pattern in this embodiment is designed as blade blocks that are independent of each other and arranged in multiple rows and columns. The MTF values corresponding to each blade block in the formed thermal map are also neatly arranged in rows and columns. This arrangement makes it easier to compare and analyze different rows and columns in the thermal map to find out their changing trends.
[0059] On the basis of the above technical solution, in some optional embodiments, judging whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map may include: judging whether the modulation transfer function value of the design pattern in the thermal map satisfies the trend of the lens theoretical modulation transfer function; if so, the optical axis is not offset; otherwise, the optical axis is offset. In this embodiment, after the horizontal adjustment, the thermal map of the test pattern obtained by the first shooting can be used to directly judge whether the optical axis is offset. If the change trend of the modulation transfer function value of the design pattern in the thermal map is consistent with the trend of the lens theoretical modulation transfer function, it means that the optical axis is not offset. If the change trend of the modulation transfer function value of the design pattern in the thermal map is inconsistent with the trend of the lens theoretical modulation transfer function, it means that the optical axis is offset.
[0060] Further, in some embodiments, the step of determining whether the modulation transfer function value of the design pattern in the heat map satisfies the lens theory modulation transfer function trend may include: if the modulation transfer function value of the central area of the heat map is higher than the modulation transfer function value of the surrounding area, and the modulation transfer function values in the heat map are symmetrically distributed, then the modulation transfer function value of the design pattern in the heat map satisfies the lens theory modulation transfer function trend. Figure 6 As shown, in this embodiment, the modulation transfer function values of 9 rows and 11 columns corresponding to the blade blocks in 9 rows and 11 columns will be presented in the thermal map. The modulation transfer function value of the first column and the modulation transfer function value of the last column (i.e., the 11th column) in the thermal map can be compared. If the difference between the two columns of data is large, it means that the imaging uniformity is poor. At the same time, the modulation transfer function value of the central area in the thermal map is not high and the surrounding area is low. At this time, the modulation transfer function value of the design pattern in the thermal map does not meet the trend of the lens theoretical modulation transfer function, indicating that the optical axis is offset (i.e. Figure 6 and Figure 7From the results shown, we can see that the data difference between the first column and the last column is large, and the imaging uniformity is poor); if the difference between the modulation transfer function values of the first column and the last column is small, it means that the symmetry is good. At the same time, the modulation transfer function value of the central area in the thermal map is higher than that of the surrounding area. At this time, the modulation transfer function value of the design pattern in the thermal map meets the modulation transfer function trend of the lens theory, and the imaging uniformity is good.
[0061] Furthermore, in one embodiment, after determining whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map, the following steps may be further included:
[0062] S2: If it is determined that the optical axis of the combination of the camera and lens to be tested is offset, the tilt angle of the fixture is adjusted, and the combination of the camera and lens to be tested is used to shoot a screen displaying a design pattern to obtain an adjustment map, which is converted into a heat map and the tilt direction of the optical axis is determined based on the heat map.
[0063] In this embodiment, the horizontality of the jig is initially adjusted so that the horizontality of the jig and the screen is maintained below a preset angle value; when it is determined that the optical axis is offset, the jig can be further adjusted so that the jig is tilted to the upper right or lower left relative to the screen, and the screen is photographed again to obtain an adjustment map. The inclination direction of the optical axis can be determined based on the heat map of the adjustment map. That is, this embodiment can not only verify that the optical axis is indeed tilted by adjusting the jig, but also determine the specific inclination direction of the optical axis, thereby providing a clear direction for subsequent adjustment of the optical axis.
[0064] Further, in some embodiments, the adjusting the tilt angle of the fixture, and using the combination of the camera to be tested and the lens to shoot the screen displaying the design pattern to obtain an adjustment map, converting the adjustment map into a heat map and determining the tilt direction of the optical axis based on the heat map, may include:
[0065] S21: adjusting a fixture connected to the camera so that the fixture is tilted relative to the screen in a first direction at a preset angle, and photographing the screen using a combination of the camera to be tested and the lens to obtain an adjustment diagram.
[0066] S22: converting the adjustment image into a thermal map, and comparing the uniformity of the thermal map of the adjustment image with the thermal map of the test image; if the thermal map of the adjustment image is more uniform than the thermal map of the test image, the inclination direction of the optical axis is opposite to the first direction; if the thermal map of the test image is more uniform than the thermal map of the adjustment image, the inclination direction of the optical axis is the same as the first direction.
[0067] In this embodiment, the first direction can be the upper right direction or the upper left direction. When adjusting, it can be selected according to the actual situation. This embodiment is first described by taking the upper right direction as the first direction. When adjusting, the fixture can be tilted 1° to the upper right (↗) relative to the screen. At this time, take a picture in a dark room to obtain an adjustment map, and calculate the MTF in the adjustment map to obtain a thermal map. The result is as follows: Figure 8 As shown in the figure, by comparing and analyzing the column data, it can be found that after tilting the fixture to the upper right, the MTF data of the leftmost and rightmost columns are close ( Fig. 9 As shown in the figure, the thermal image is close to the theoretical MTF trend, with high center and low surrounding, and symmetry and good uniformity. Figure 6 The uniformity of the thermal map of the test image shown in the figure is poor, so it can be determined that the tilt direction of the optical axis is tilted to the left. Further, if the first direction is the upper left, when adjusting, the fixture can be tilted 1° to the upper left (↖) relative to the screen. At this time, take a picture under dark room conditions to obtain the adjustment map, and calculate the MTF in the adjustment map to obtain the thermal map. The result is as follows: Fig.10 As shown, by comparing the column data ( Fig.11 As shown in Figure 2, it can be found that after the fixture is tilted to the upper left, the MTF data of the leftmost and rightmost columns are compared with Figure 7 The difference in is larger and the uniformity is worse; in comparison, Fig.11 The thermal map of the test pattern shown in has good uniformity, so it can be determined that the tilt direction of the optical axis is tilted to the left.
[0068] Furthermore, in one embodiment, after determining whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map, the following steps may be further included:
[0069] S3: If it is determined that the optical axis of the combination of the camera and lens to be tested is offset, the fixture connected to the camera is adjusted so that the fixture is gradually tilted by a preset angle in a first direction relative to the screen, and the screen is photographed using the combination of the camera and lens to be tested after each tilt by the preset angle to obtain multiple adjustment images.
[0070] S4: converting multiple adjustment maps into thermal maps, and finding the thermal map closest to the trend of the theoretical modulation transfer function of the lens. The tilt angle corresponding to the thermal map closest to the trend of the theoretical modulation transfer function of the lens is the optical axis tilt angle with the best imaging uniformity.
[0071] Specifically, the jig can be first tilted 1° to the upper right relative to the screen, and the screen can be photographed to obtain an adjustment graph; then the jig can be tilted 1° to the upper right relative to the screen (at this time, the jig has been tilted 2° to the upper right relative to the screen), and the screen can be photographed to obtain an adjustment graph; then the jig can be tilted 1° to the upper right relative to the screen (at this time, the jig has been tilted 3° to the upper right relative to the screen), and the screen can be photographed to obtain an adjustment graph, and so on, obtaining an adjustment graph after each tilt of 1°, and each adjustment graph is converted into a thermal map after obtaining it. As the angle of the jig is gradually tilted, when it is found that the uniformity of the thermal map changes from gradually getting better to getting worse, the jig can be stopped from being tilted further. At this time, the thermal map with the best uniformity is the thermal map that is closest to the trend of the theoretical modulation transfer function of the lens. At the same time, the total tilt angle of the jig corresponding to the thermal map is the optical axis tilt angle with the best imaging uniformity.
[0072] If it is found that after the fixture is tilted 1° to the upper right relative to the screen, the uniformity of the thermal map obtained is worse than that when it is not tilted, the fixture can be adjusted in the opposite direction, that is, tilt the fixture to the upper left relative to the screen, and gradually obtain the adjustment map and thermal map after each tilt, and compare and analyze them to obtain the optical axis tilt angle with the best imaging uniformity.
[0073] By adopting the method provided in the above embodiment, the inclination angle of the optical axis with good imaging uniformity can be obtained, and imaging can be performed using this angle.
[0074] Further, see Figure 3 As shown, in some embodiments, the method of using the combination of the camera and the lens to be tested to shoot a screen displaying a design pattern to obtain a test pattern, converting the test pattern into a thermal map, and judging whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map may include:
[0075] S11: Using a combination of a camera and a lens to be tested to photograph a screen displaying a design pattern, to obtain a first test image.
[0076] S12: After changing the back focal length of the lens, the combination of the camera to be tested and the lens is used again to shoot the screen displaying the design pattern to obtain a second test image.
[0077] In this step, the lens can be rotated to increase or decrease the back focal length of the lens, and the direction of the lens in the lens will also change. After changing the back focal length and the direction of the lens, the second test image is captured again to obtain the second test image.
[0078] S13: Converting the first test image and the second test image into thermal maps, and comparing whether the thermal maps of the first test image and the second test image are the same; if they are not the same, it indicates that the optical axis of the combination of the camera and the lens to be tested is offset.
[0079] In this embodiment, the conversion to a thermal map in step S13 can be performed simultaneously with step S11 and step S12, that is, after obtaining the first test image, the first test image can be directly converted into a thermal map, and after obtaining the second test image, the second test image can be directly converted into a thermal map. This embodiment uses the method of changing the rear focal length of the lens to determine whether the optical axis is offset. This method can directly rotate the lens, and it is not necessary to ensure that the level between the fixture and the screen is very high. It can also measure whether the optical axis is offset, and the detection method is more convenient; that is, this method is suitable for scenes with a very high level between the fixture and the screen (the level is kept below 0.02°), and can also be used for scenes with low level between the fixture and the screen, and can detect whether the optical axis is offset.
[0080] By comparing the following Table 1, it can be seen that after the lens is rotated, the position of the best imaging area changes, that is, after the lens is rotated 180°, the position of the best imaging area of the image obtained is different from the position of the best imaging area when the lens is at 0°.
[0081] Table 1
[0082]
[0083] Further, in some optional embodiments, before the test pattern is obtained by using the combination of the camera and lens to be tested to shoot the screen displaying the design pattern, it may also include: focusing the combination of the camera and lens to be tested, and when the image is enlarged and a preset number of transition pixels are present, the focus is successful. In this embodiment, before shooting the test pattern to measure MTF, focus processing is first performed, and the image is enlarged to see the transition pixels. When about 1 to 2 transition pixels are seen, the focus is successful. In this embodiment, focusing first and then measuring MTF can ensure that the test pattern shot after focusing is as clear as possible. After converting to a thermal map, the MTF value in the thermal map is also more accurate.
[0084] The method for detecting the optical axis offset of the camera lens assembly provided in the embodiment of the present application can be used for the detection of high-precision MTF imaging and high-standard imaging uniformity in machine vision, thereby improving the requirements of machine vision imaging by determining whether the optical axis of the camera and the lens is offset.
[0085] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.
[0086] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.
[0087] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.
Claims
1. A method for detecting optical axis offset of camera lens assembly, characterized in that: It includes the following steps: A screen displaying a design pattern is photographed using a combination of a camera and a lens to be tested to obtain a test pattern, the test pattern is converted into a thermal map, and based on the thermal map, it is determined whether the optical axis of the combination of the camera and the lens to be tested is offset.
2. The method according to claim 1, characterized in that Before using the combination of the camera to be tested and the lens to photograph the screen displaying the design pattern to obtain the test image, the method further includes: Adjust the fixture connected to the camera to keep the level between the fixture and the screen below the preset angle value.
3. The method according to claim 2, characterized in that The method of judging whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map includes: Determine whether the modulation transfer function value of the design pattern in the thermal map satisfies the modulation transfer function trend of the lens theory; If so, the optical axis does not have an offset; otherwise, the optical axis does have an offset.
4. The method according to claim 3, characterized in that The step of judging whether the modulation transfer function value of the design pattern in the thermal map satisfies the modulation transfer function trend of the lens theory includes: If the MTF value in the center area of the heat map is higher than that in the surrounding areas, and the MTF values in the heat map are symmetrically distributed, the MTF value of the design pattern in the heat map satisfies the MTF trend of the lens theory.
5. The method according to claim 2, characterized in that After determining whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map, the method further includes: If it is determined that the optical axis of the combination of the camera and lens to be tested is offset, the tilt angle of the fixture is adjusted, and the combination of the camera and lens to be tested is used to shoot a screen displaying a design pattern to obtain an adjustment map, which is converted into a heat map and the tilt direction of the optical axis is determined based on the heat map.
6. The method according to claim 5, characterized in that The adjusting device includes adjusting the tilt angle of the fixture, and using a combination of a camera and a lens to be tested to shoot a screen displaying a design pattern to obtain an adjustment map, converting the adjustment map into a thermal map, and determining the tilt direction of the optical axis based on the thermal map, including: Adjusting a fixture connected to the camera so that the fixture is tilted relative to the screen in a first direction at a preset angle, and photographing the screen using a combination of the camera to be tested and the lens to obtain an adjustment diagram; Convert the adjustment image into a heat map, and compare the uniformity of the heat map of the adjustment image with the heat map of the test image; If the thermal map of the adjustment image is more uniform than the thermal map of the test image, the tilt direction of the optical axis is opposite to the first direction; if the thermal map of the test image is more uniform than the thermal map of the adjustment image, the tilt direction of the optical axis is the same as the first direction.
7. The method according to claim 2, characterized in that After determining whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map, the method further includes: If it is determined that the optical axis of the combination of the camera and the lens to be tested is offset, the jig connected to the camera is adjusted so that the jig is gradually tilted in the first direction relative to the screen by a preset angle, and the screen is photographed using the combination of the camera and the lens to be tested after each tilt by the preset angle to obtain multiple adjustment images; Convert multiple adjustment maps into thermal maps, and find the thermal map that is closest to the trend of the theoretical modulation transfer function of the lens. The tilt angle corresponding to the thermal map that is closest to the trend of the theoretical modulation transfer function of the lens is the optical axis tilt angle with the best imaging uniformity.
8. The method according to claim 1, characterized in that The method uses the combination of the camera and the lens to be tested to shoot a screen displaying a design pattern to obtain a test pattern, converts the test pattern into a thermal map, and determines whether the optical axis of the combination of the camera and the lens to be tested is offset based on the thermal map, including: Using a combination of a camera and a lens to be tested to shoot a screen displaying a design pattern, to obtain a first test image; After changing the back focal length of the lens, the combination of the camera to be tested and the lens is used again to shoot the screen displaying the design pattern to obtain a second test image; Converting the first test image and the second test image into thermal maps, and comparing whether the thermal maps of the first test image and the second test image are the same; If they are not the same, it means that the optical axis of the combination of the camera and lens to be tested is offset.
9. The method according to claim 1, characterized in that The design pattern is a plurality of blade blocks displayed in the screen body, and the plurality of blade blocks are evenly arranged in a plurality of rows and columns.
10. The method according to claim 1, characterized in that Before using the combination of the camera to be tested and the lens to photograph the screen displaying the design pattern to obtain the test image, the method further includes: Focus the combination of the camera and lens to be tested. When the image is magnified and a preset number of transition pixels appear, the focus is successful.