An automatic centering method for lens MTF testing

Abstract

The present application relates to the technical field of lens testing, and particularly relates to an automatic centering method for lens MTF testing, a special driving disc is designed for lens structure, and a plurality of uniformly arranged hole positions are arranged on the special driving disc; when an MTF testing machine tests one to-be-tested lens, the special driving disc is moved to pre-align the center of the to-be-tested lens with the center of a Reticle of the MTF testing machine and the center of an optical axis of a center camera; an active path is designed for the to-be-tested lens, and the special driving disc is moved according to the active path; an image is acquired by the center camera each time the to-be-tested lens is moved, and a 'H' type feature is found by using a Hough transform principle; and the actual eccentric distance of the lens is calculated to realize automatic centering. According to the moving algorithm of the special driving disc and the image processing algorithm of the 'H' type feature, the present application can complete fast and accurate automatic centering; the method of the present application can compensate for the processing error of the driving disc, can reduce the processing precision requirement of the driving disc, and can realize automatic testing of the whole lens.

Description

Technical Field

[0001] This invention relates to the field of lens testing technology, and specifically to an automatic alignment method for lens MTF testing. Background Technology

[0002] During testing, the lens is placed on the holes of a dedicated drive plate. This drive plate is custom-machined for the lens structure, and the holes are spaced at fixed intervals to accommodate one lens under test. The position of the lens under test is adjusted by moving the drive plate using the control motor of the MTF testing machine. Ideally, once the first lens under test is correctly aligned manually, subsequent lenses can be aligned by simply moving the motor a fixed distance.

[0003] However, the dedicated drive disk, being a machined part, has certain machining errors. This can cause the drive disk to fail to achieve the desired effect after moving according to the aforementioned distance, resulting in severe misalignment in the imaging system. Therefore, a centering method is needed to achieve automatic program centering, improve testing efficiency, and realize fully automated testing of the drive disk. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art and to provide an automatic alignment method for lens MTF testing.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an automatic alignment method for lens MTF testing, comprising the following steps:

[0006] Step 1: Design a special drive plate for the lens structure. The special drive plate is provided with several evenly arranged holes. Place several lenses in the holes and place the special drive plate on the MTF test machine. Test the lenses in sequence through the MTF test machine.

[0007] Step 2: When testing one of the lenses under test on the MTF test machine, move the special drive disk to pre-align the center of the lens under test with the center of the Reticle and the center of the optical axis of the central camera on the MTF test machine. The image of the Reticle is "H" shaped.

[0008] Step 3: Design an active path for the lens under test and move the dedicated drive disk along the active path. Each time the lens under test is moved, an image is acquired through the central camera. The Hough transform principle is used to determine whether the image has an "H"-shaped feature. If an "H"-shaped feature is found, stop moving the lens under test.

[0009] Step 4: By calculating the centroid position of the "H" shape, the number of off-center pixels of the "H" shape in the image is calculated. Finally, based on the camera imaging principle, the actual off-center distance of the lens is calculated, and then the special drive disk is driven to move in the opposite direction according to the actual off-center distance to achieve automatic alignment.

[0010] Furthermore, the transverse and longitudinal spacing of the hole centers on the special drive disc is both 9.5 mm.

[0011] Furthermore, the movement path of the lens under test consists of movement in the X direction and movement in the Y direction. Each movement is only in the X or Y direction. The overall movement path moves outward around the initial position in a spiral trajectory structure.

[0012] Furthermore, the motion path of the lens under test is calculated based on the resolution of the central camera;

[0013] The resolution of the central camera is 720*540, and the actual distance between the two vertical lines of the Reticle “H” shape is D. H =0.1mm, the center camera is a CCD industrial camera, the pixel size of the center camera is 7.4um, based on the lens under test EFL1 and the industrial camera lens EFL2, the system magnification Mag = EFL2 / EFL1 ≈ 16 is calculated; the number of pixels between the two vertical lines of the "H" shape is obtained as ΔH = D H *1000*Mag / 7.4≈220Pixel; The distance between the horizontal line of the “H” shape and the top and bottom edges of the image is 540 / 2=270Pixel;

[0014] Finally, the calculated step size in the X direction was 50 μm, and the step size in the Y direction was 125 μm.

[0015] Furthermore, the Hough transform principle is used to determine whether an image exhibits an "H"-shaped feature, specifically including:

[0016] If an "H"-shaped feature exists, it means that there are three straight lines in the image, namely two vertical lines and one horizontal line. In polar coordinates, the equation of the straight line can be expressed as: r = xcosθ + ysinθ;

[0017] For passing through point (x) 0 ,y 0 The family of lines r can be represented as: θ =x 0 cosθ+y 0 sinθ means that (rθ, θ) can represent a path through (x) 0 ,y 0 (a straight line);

[0018] Given a point (x) 0 ,y0 By plotting all the straight lines passing through the polar radius and polar angle plane in polar coordinates, a sine curve can be obtained.

[0019] After performing the above operation on all points on the image edge features, multiple sine curves can be obtained, and the three sine curves intersect at a point (θ, a). θ If , then we can consider that there exists a straight line (θ, a). θ (Simultaneously passing through these three points;)

[0020] The Hough transform principle uses an algorithm to automatically track the intersection points between curves corresponding to each point in an image. If the number of curves intersecting at the same point exceeds a threshold we set, then the line represented by that intersection point can be considered a line in the image. When three lines that form an "H" shape are found in the image, it is considered that an "H" shape has appeared.

[0021] Determine if an "H" shape appears in the image. If not, control the lens under test to move tentatively along a preset trajectory. At each position point, repeat the Hough transform principle to determine the image until an "H" shape appears in the image.

[0022] Furthermore, the calculation of the centroid position of the "H" shape includes: in pixel coordinates, the average of the horizontal coordinates of the two vertical lines of the "H" is used as the horizontal coordinate x of the centroid of the "H", and the average of the vertical coordinates of the horizontal lines of the "H" is used as the vertical coordinate y of the centroid. After obtaining x and y, the difference between them and the coordinates of the image center can be used to calculate the number of eccentric pixels ΔX and ΔY of the "H".

[0023] Furthermore, the pixel difference is converted to the actual distance. The off-center pixel distance of the "H" centroid in the X direction is X_Pixel = 7.4 * ΔX, and the off-center pixel distance in the Y direction is Y_Pixel = 7.4 * ΔY.

[0024] The actual offset distance of the lens under test in the X direction is: X_Dis=X_Pixel / Mag(um);

[0025] The actual offset distance in the Y direction of the lens under test is: Y_Dis=Y_Pixel / Mag(um).

[0026] The beneficial effects of this invention are as follows: As described above, compared with the prior art, the automatic alignment method for lens MTF testing of this invention first moves a dedicated drive disk via the control motor of the MTF testing machine to pre-align the center of the lens under test with the center of the Reticle and the optical axis center of the central camera during the MTF testing process. An activity path is designed for the lens under test, and images are acquired. The Hough transform principle is used to determine whether an "H"-shaped feature appears in the image. By calculating the centroid position of the "H" shape, the number of off-center pixels of the "H" shape in the image is calculated. Finally, based on the camera imaging principle, the actual off-center distance of the lens is calculated, and the dedicated drive disk is driven to move in the opposite direction according to the actual off-center distance to achieve automatic alignment. This ensures that the lens imaging system during testing will not experience severe off-center phenomena, improving the accuracy of the test. This invention uses a dedicated drive disk movement algorithm and an image processing algorithm for the "H"-shaped feature to complete fast and accurate automatic alignment. The method of this invention provides necessary compensation for drive disk processing errors, which can reduce the requirements for drive disk processing precision and realize automated testing of the entire lens disk. Attached Figure Description

[0027] Figure 1 This is a flowchart of the steps of an automatic alignment method for lens MTF testing in a preferred embodiment of the present invention;

[0028] Figure 2 This is a partial structural diagram of the MTF testing machine in a preferred embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the movement path of the lens under test in a preferred embodiment of the present invention;

[0030] Reference numerals: 1. Dedicated drive disk; 2. Reticle; 3. Central camera; 4. Lens under test. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, 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. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] Reference Figure 1-3 As shown, a preferred embodiment of the present invention provides an automatic alignment method for lens MTF testing, comprising the following steps:

[0035] Step 1: Design a dedicated drive plate 1 for the lens structure. The dedicated drive plate 1 is provided with several evenly arranged holes. Place several lenses in the holes and place the dedicated drive plate 1 on the MTF testing machine. Test the lenses in sequence through the MTF testing machine.

[0036] The working principle of the MTF tester is to reverse the positions of the object and the image in the lens imaging system, place the object to be imaged on the image plane of the lens under test, and place the camera at the object plane position of the lens under test to take a picture, so as to obtain the MTF values ​​of the center image field and / or the peripheral image field of the lens under test in the normal direction S and / or the tangential direction T.

[0037] Step 2: When testing one of the lenses 4 under test on the MTF test machine, the special drive disk 1 is moved so that the center of the lens 4 under test is pre-aligned with the center of the Reticle 2 and the optical axis center of the central camera 3 of the MTF test machine. The image of the Reticle 2 is "H" shaped.

[0038] The MTF testing machine includes a Reticle2 center and a central camera 3. The Reticle2 is the object to be imaged, and the image is a common "H" shape for testing. The central camera 3 is the camera directly above the Reticle2. There are also cameras around the central camera 3 to take pictures of the Reticle2. During testing, the lens under test 4 should be located in the exact middle of the Reticle2 and the central camera 3, that is, in the test center. It is necessary to move the special drive disk 1 to pre-align the center of the lens under test 4 with the center of the Reticle2 and the optical axis center of the central camera 3 of the MTF testing machine.

[0039] Step 3: Design an active path for the lens under test 4 and move the special drive disk 1 along the active path. Each time the lens under test 4 moves, it acquires an image through the central camera 3. Use the Hough transform principle to determine whether the image has an "H" shape feature. If an "H" shape feature appears, stop moving the lens under test 4.

[0040] Since the lens under test 4 may not be located at the test center, it needs to be moved to the test center. This is an optimal moving process. To avoid missing the test center, the activity path needs to be designed according to the specific parameters of the lens under test 4 and the MTF test machine to ensure that the test center is found in a shorter time. Each time the lens under test 4 is moved, an image is acquired through the central camera 3. Since automatic centering is required instead of manual observation of the image, the Hough transform principle needs to be used to allow the control system of the MTF test machine to automatically determine whether the image has an "H" shaped feature. If an "H" shaped feature appears, it means that the position closest to the test center has been found, and the movement of the lens under test 4 is stopped.

[0041] Step 4: By calculating the centroid position of the "H" shape, the number of off-center pixels of the "H" shape on the image is calculated. Finally, based on the camera imaging principle, the actual off-center distance of the lens is calculated, and then the dedicated drive disk 1 is driven to move in the opposite direction according to the actual off-center distance to achieve automatic alignment.

[0042] The MTF testing machine's control system automatically calculates the centroid position of the "H" shape, i.e., the center position of the image. Since this is the image after being imaged by the lens under test 4, the number of off-center pixels of the "H" shape on the image needs to be calculated. Finally, based on the camera imaging principle, the actual off-center distance of the lens is calculated. By driving the dedicated drive disk 1 to move in the opposite direction according to the actual off-center distance, the lens under test 4 is moved to the test center, thus achieving automatic alignment. The entire process is automatically operated by the MTF testing machine's control system, improving testing efficiency and accuracy.

[0043] The automatic alignment method for lens MTF testing of the present invention first moves a dedicated drive disk 1 via the control motor of the MTF testing machine to pre-align the center of the lens under test 4 with the center of Reticle 2 and the optical axis center of the central camera 3. An activity path is designed for the lens under test 4 and images are acquired. The Hough transform principle is used to determine whether an "H"-shaped feature appears in the image. By calculating the centroid position of the "H" shape, the number of off-center pixels of the "H" shape in the image is calculated. Finally, based on the camera imaging principle, the actual off-center distance of the lens is calculated, and the dedicated drive disk 1 is driven to move in the opposite direction according to the actual off-center distance to achieve automatic alignment. This ensures that the lens imaging system does not exhibit severe off-center phenomena during testing, improving the accuracy of the test. The present invention uses the movement algorithm of the dedicated drive disk 1 and the image processing algorithm of the "H"-shaped feature to complete the fast and accurate automatic alignment work. The method of the present invention provides necessary compensation for the processing error of the drive disk, which can reduce the processing accuracy requirements of the drive disk and realize the automated testing of the entire lens disk.

[0044] As a preferred embodiment of the present invention, it may also have the following additional technical features:

[0045] In this embodiment, the horizontal and vertical spacing between the center of the holes on the dedicated drive plate 1 is 9.5 mm. During MTF testing, to improve testing efficiency and complete the testing of multiple lenses at once, the MTF testing machine has a station for placing the dedicated drive plate 1, and a control motor drives the dedicated drive plate 1 to move. The dedicated drive plate 1 has several holes for placing lenses, and the horizontal and vertical spacing between adjacent holes is fixed to facilitate the processing of the dedicated drive plate 1. The dedicated drive plate 1 has its center of the holes set to 9.5 mm according to the size of the station on the MTF testing machine. Since the dedicated drive plate 1 is a machined part, there will be certain processing errors, and the processed spacing may not be 9.5 mm. Therefore, when the first lens is tested and the control motor drives the dedicated drive plate 1 to move 9.5 mm to test the next lens, due to the processing error of the dedicated drive plate 1, the center of the next lens will not be aligned with the center of Reticle 2 and the optical axis center of the central camera 3. Therefore, a serious eccentricity phenomenon will occur during testing, affecting the measurement accuracy.

[0046] In this embodiment, the movement path of the lens under test 4 consists of movement in the X and Y directions. Each movement occurs only in the X or Y direction, and the overall movement path follows a spiral trajectory structure, moving outward from the initial position. The single movement of the lens under test 4 in the X or Y direction facilitates path control and improves step accuracy. To avoid missing the test center, it is necessary to scan outward from the initial position, continuously expanding the scanning range until an "H"-shaped feature is found. The spiral trajectory structure composed of horizontal and vertical lines prevents omissions of position points and avoids missing the test center. (Refer to...) Figure 3 As shown, starting from the initial position of point 01, we search outwards for the "H" shaped feature.

[0047] In this embodiment, the movement path of the lens 4 under test is calculated based on the resolution of the central camera 3;

[0048] The resolution of the central camera 3 is 720*540, and the actual distance between the two vertical lines of the Reticle 2 “H” shape is D. H =0.1mm, the center camera 3 is a CCD industrial camera, the pixel size of the center camera 3 is 7.4um, based on the lens under test 4 EFL1 and the industrial camera lens EFL2, the system magnification Mag = EFL2 / EFL1≈16 is calculated; the number of pixels between the two vertical lines of the "H" shape is obtained as ΔH = D H *1000*Mag / 7.4≈220Pixel; The distance between the horizontal line of the “H” shape and the top and bottom edges of the image is 540 / 2=270Pixel;

[0049] When the motor moves in the X direction (searching for two vertical lines), after finding one vertical line, the minimum movement distance for the motor to search for the other vertical line is DH / 2 = 50µm. To improve search efficiency and avoid missing "H", the step size in the X direction is set to 50µm in this method. When the motor moves in the Y direction (searching for horizontal lines), if the "H" horizontal line disappears, the minimum movement distance for the motor to find the "H" horizontal line and make it approximately centered should be 270Pixel*7.4µm / Pixel / Mag = 125µm. To improve the efficiency of the search algorithm and quickly find the test center, the search step size in the Y direction is set to 125µm in this method. Finally, the movement step size in the X direction is 50µm, and the movement step size in the Y direction is 125µm.

[0050] In this embodiment, the Hough transform principle is used to determine whether an image exhibits an "H"-shaped feature, specifically including:

[0051] If an "H"-shaped feature exists, it means that there are three straight lines in the image, namely two vertical lines and one horizontal line. In polar coordinates, the equation of the straight line can be expressed as: r = xcosθ + ysinθ;

[0052] For passing through point (x) 0 ,y 0 The family of lines (x, θ) can be represented as: rθ = x0cosθ + y0sinθ, which means that (rθ, θ) can represent a line passing through (x, θ). 0 ,y 0 (a straight line);

[0053] If a point (x0, y0) is given, a sine curve can be obtained by drawing all the straight lines passing through it in the polar coordinate plane with respect to the polar radius and polar angle.

[0054] After performing the above operation on all points on the image edge features, multiple sine curves can be obtained, and the three sine curves intersect at a point (θ, a). θ If , then we can consider that there exists a straight line (θ, a). θ (Simultaneously passing through these three points;)

[0055] The Hough transform principle uses an algorithm to automatically track the intersection points between curves corresponding to each point in an image. If the number of curves intersecting at the same point exceeds a threshold we set, then the line represented by that intersection point can be considered a line in the image. When three lines that form an "H" shape are found in the image, it is considered that an "H" shape has appeared.

[0056] Determine whether an "H" shape appears in the image. If not, control the lens 4 under test to move tentatively along a preset trajectory. At each position point, repeat the judgment of the image using the Hough transform principle until an "H" shape appears in the image.

[0057] In this embodiment, the calculation of the centroid position of the "H" shape includes: on the pixel coordinates, the average of the horizontal coordinates of the two vertical lines of the "H" is used as the horizontal coordinate x of the centroid of the "H", and the average of the vertical coordinates of the horizontal lines of the "H" is used as the vertical coordinate y of the centroid. After obtaining x and y, the difference between them and the coordinates of the image center can be used to calculate the number of eccentric pixels ΔX and ΔY of the "H".

[0058] In this embodiment, the pixel difference is converted to the actual distance. The off-center pixel distance of the centroid of "H" in the X direction is X_Pixel = 7.4 * ΔX, and the off-center pixel distance in the Y direction is Y_Pixel = 7.4 * ΔY.

[0059] The actual offset distance of the lens under test in the 4X direction is: X_Dis=X_Pixel / Mag(um);

[0060] The actual eccentricity distance of the lens under test in the 4Y direction is: Y_Dis=Y_Pixel / Mag(um).

[0061] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.

[0062] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. An auto-centering method for lens MTF testing, characterized in that, The method comprises the following steps: Step 1, a special drive disc (1) is designed for lens structure, a plurality of uniformly arranged hole positions are arranged on the special drive disc (1), a plurality of lenses are placed in the hole positions, the special drive disc (1) is placed on an MTF test machine, and the lenses are sequentially tested by the MTF test machine; Step 2, when one of the lenses (4) to be tested is tested by the MTF test machine, the special drive disc (1) is moved to make the center of the lens (4) to be tested pre-aligned with the center of a Reticle (2) and the optical axis center of a center camera (3) of the MTF test machine, and the image of the Reticle (2) is in the shape of "H"; Step 3, an active path is designed for the lens (4) to be tested, and the special drive disc (1) is moved according to the active path, the image is acquired by the center camera (3) every time the lens (4) to be tested is moved, whether the image appears the "H" feature is judged by using the Hough transform principle, and if the "H" feature appears, the lens (4) to be tested is stopped; Step 4, the eccentric pixel number of the "H" in the image is calculated by calculating the centroid position of the "H", and finally the actual eccentric distance of the lens is calculated by the camera imaging principle, and then the special drive disc (1) is reversely moved according to the actual eccentric distance, so that automatic centering is realized; whether the image appears the "H" feature is judged by using the Hough transform principle, and the specific process comprises the following steps: If the "H" feature exists, it means that there are three straight lines in the image, that is, two vertical lines and one horizontal line, and the straight line equation can be expressed as r = xcosθ + ysinθ in polar coordinates; For a cluster of straight lines passing through the point (x0, y0) can be expressed as: r θ = x0cosθ + y0sinθ, which means that (rθ, θ) can represent a straight line passing through (x0, y0); If a point (x0, y0) is given, all straight lines passing through the point can be drawn on the polar radial and polar angle plane to obtain a sinusoidal curve; After the above operation is performed on all points on the edge feature of the image, a plurality of sinusoidal curves can be obtained, and three sinusoidal curves intersect at a point (θ, a θ ). It can be considered that there is a straight line (θ, a θ ) passing through the three points simultaneously. The Hough transform principle is to automatically track the intersection point between each point in the image and the corresponding curve by using an algorithm, if the number of curves intersecting at the same point exceeds the threshold value set by us, it can be considered that the straight line represented by the intersection point is a straight line in the image, and when three straight lines constituting the "H" are found in the image, it is considered that the "H" appears; whether the image appears the "H" feature is judged by using the Hough transform principle, and the specific process comprises the following steps: The calculation of the centroid position of the "H" comprises the following steps: in the pixel coordinates, the average value of the horizontal coordinates of the two vertical lines of the "H" is taken as the centroid horizontal coordinate x of the "H", and the average value of the vertical coordinates of the horizontal line of the "H" is taken as the centroid vertical coordinate y, and after x and y are obtained, the difference between the centroid coordinates and the image center coordinates can be calculated to obtain the eccentric pixel number ΔX and ΔY of the "H".

2. The automatic centering method for lens MTF test according to claim 1, characterized in that, The horizontal and vertical spacings of the hole centers of the special drive disc (1) are both 9.5 mm.

3. The automatic centering method for lens MTF test according to claim 1, wherein, The active path of the lens (4) to be tested is composed of X direction movement and Y direction movement, and single active movement is only in the X direction or the Y direction, and the overall active path spirally surrounds the initial position from the initial position to the periphery.

4. The automatic centering method for lens MTF test according to claim 3, characterized in that, The active path of the lens (4) to be tested is calculated according to the resolution of the center camera (3); The resolution of the center camera (3) is 720*540, and the actual distance between the two vertical lines of the Reticle (2) "H" type is D H =0.1mm, the center camera (3) is a CCD industrial camera, the pixel size of the center camera (3) is 7.4um, according to the EFL1 of the lens to be tested (4) and the EFL2 of the industrial camera lens, the system magnification Mag=EFL2 / EFL1≈16 is calculated; the interval pixel number of the two vertical lines of the "H" type is ΔH=D H *1000*Mag / 7.4≈220Pixel; the pixel number of the horizontal line distance from the upper and lower image edges of the "H" type is 540 / 2=270Pixel; Finally, the moving step distance in the X direction is calculated as 50 um, and the moving step distance in the Y direction is calculated as 125 um.

5. The automatic centering method for lens MTF testing according to claim 1, wherein, The pixel difference is converted into the actual distance, and the eccentric pixel distance of the "H" centroid in the X direction is X_Pixel=7.4*ΔX, and the eccentric pixel distance in the Y direction is Y_Pixel=7.4*ΔY; The actual eccentric distance of the to-be-tested lens (4) in the X direction is X_Dis=X_Pixel / Mag (um); The actual eccentric distance of the to-be-tested lens (4) in the Y direction is Y_Dis=Y_Pixel / Mag (um).

Images