A close distance line scan lens and machine vision equipment

Abstract

The application discloses a near object distance line scanning lens and machine vision equipment. The lens is sequentially provided with a first lens unit with positive refractive power, a diaphragm and a second lens unit with positive refractive power from an object side to an image side. The first lens unit sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens from the object side to the image side. The second lens unit sequentially comprises a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens and a thirteenth lens from the object side to the image side. The lens satisfies the following conditions: 350mm < WD < 440mm; 1.50 < DW / DI < 2.50; 2.90 < |f G1 / f| < 5.10; 0.10 < |f G2 / f| < 1.90. In the formula, WD is the working object distance of the lens, DW is the object side observation field diameter range of the lens, DI is the image side imaging circle diameter, f is the focal length of the lens, f G1 is the focal length of the first lens unit, and f G2 is the focal length of the second lens unit. The application aims to provide a near object distance line scanning lens and machine vision equipment with high optical performance.

Description

Technical Field

[0001] This invention relates to the field of line scanning lens technology, and more particularly to a near-object distance line scanning lens and machine vision equipment. Background Technology

[0002] With the continuous development of machine vision, large-area line scanning lenses are widely used in various industries, especially in the high-demand lithium battery industry of the automotive market. Automated inspection equipment is indispensable in all stages of lithium battery production, including appearance defect detection, dimensional accuracy inspection, connector welding quality inspection, internal cell inspection, and label quality inspection. As a key link in ensuring the efficiency and quality of lithium battery manufacturing, machine vision faces increasing demands for large-field-of-view and high-precision inspection. Using line scanning lenses to acquire and analyze images of lithium battery products to detect defects, flaws, and defects, and to determine product qualification, is of great significance in lithium battery production and inspection. As a core component, the optical performance of the line scanning lens directly affects the measurement accuracy and effectiveness of the system. Currently available lithium battery line scanning inspection lenses cannot meet current needs and have at least one of the following drawbacks:

[0003] 1) Existing lithium battery line scan lenses are optimized for a single working distance, resulting in poor imaging quality at close and far object distances, and cannot be used for multiple object distances simultaneously.

[0004] 2) Existing lithium battery line scan lenses have low resolution, resulting in blurred object boundary images, excessive pixelation, low recognition accuracy, and poor detection performance during dimensional accuracy detection.

[0005] 3) Existing lithium battery line scan lenses have relatively large target surface distortion, which can easily affect measurement accuracy.

[0006] 4) Existing lithium battery line scan lenses exhibit varying resolution performance under different lighting conditions, with some showing a decrease in resolution under low lighting conditions;

[0007] 5) Existing lithium battery line scan lenses are prone to image defocusing under operating temperatures of -20℃ to +50℃;

[0008] 6) Existing lithium battery line scan lenses have significant color difference, poor color reproduction, and unsatisfactory color performance. Summary of the Invention

[0009] In view of this, the object of the present invention is to provide a near-object distance line scan lens with high optical performance and a machine vision device. This lens can at least solve one of the technical shortcomings mentioned in the background art.

[0010] According to one aspect of the present invention, a near-object distance linear scanning lens is provided, comprising, from the object side to the image side, a first lens unit having positive refractive power, an aperture, and a second lens unit having positive refractive power;

[0011] The first lens unit includes, in order from the object side to the image side, the following lenses: first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens; the second lens unit includes, in order from the object side to the image side, the following lenses: seventh lens, eighth lens, ninth lens, tenth lens, eleventh lens, twelfth lens, and thirteenth lens.

[0012] The lens satisfies the following condition:

[0013] 350mm <WD<440mm;1.50<DW / DI<2.50

[0014] 2.90<|f G1 / f|<5.10; 0.10<|f G2 / f|<1.90

[0015] In the formula, WD is the working object distance of the lens, DW is the diameter of the object-side observation field of view of the lens, DI is the diameter of the image-side imaging circle, and f is the focal length of the lens. G1 f is the focal length of the first lens unit. G2 This is the focal length of the second lens unit.

[0016] In the above technical solution, the optimal working distance of the lens is set to a near object distance of 390mm, and the system magnification is controlled at -0.5x, while also taking into account imaging conditions at the closest object distance of 350mm and the farthest object distance of 440mm. At the same time, the object-image conjugate distance is appropriately controlled to achieve the design requirement of a large field of view at a specific working distance.

[0017] In some embodiments, the first lens has positive diopter, with the object-side surface being convex and the image-side surface being concave;

[0018] The second lens has positive refractive power, and the object-side surface is convex, as is the image-side surface;

[0019] The third lens has positive refractive power, and the object side is convex, as is the image side;

[0020] The fourth lens has negative refractive power, and the object side is concave, as is the image side;

[0021] The fifth lens has negative refractive power, and the object side is concave, as is the image side;

[0022] The sixth lens has positive refractive power, and the object-side surface is convex, as is the image-side surface;

[0023] The seventh lens has positive refractive power, and the object-side surface is convex, as is the image-side surface;

[0024] The eighth lens has negative refractive power, and the object side is concave, as is the image side;

[0025] The ninth lens has positive refractive power, and the object side is convex, as is the image side;

[0026] The tenth lens has negative refractive power, and the object side is concave, as is the image side;

[0027] The eleventh lens has negative refractive power, with a concave object side and a convex image side;

[0028] The twelfth lens has positive refractive power, with a concave object side and a convex image side;

[0029] The thirteenth lens has positive refractive power, and the object side and the image side are both convex.

[0030] In the above technical solutions, large target surfaces are prone to low resolution and poor analytical power. This solution achieves a resolution of 20K by rationally allocating the optical power of each lens and using 13 optical lenses. This fully supports the use of large target surface line scan cameras with a resolution of 16K and a pixel size of 5um.

[0031] In some embodiments, the lens satisfies the following condition:

[0032] 4.80 <DS / T 12 <6.70

[0033] In the formula, DS is the aperture diameter when the lens passes through F4, and T 12 The core thickness of the seventh lens.

[0034] In the above technical solution, aberrations are optimized by setting multiple structures with different light-transmitting apertures, the aperture position is reasonably placed, and the vignetting coefficient is set to optimize the imaging quality, thus balancing the image quality performance under different light transmission conditions.

[0035] In some embodiments, the third lens is made of a glass material with a negative refractive index temperature coefficient dn / dT;

[0036] The fourth lens is made of glass material with a positive refractive index temperature coefficient dn / dT.

[0037] In the above technical solution, a reasonable combination of glass grades with positive and negative dn / dT refractive index temperature coefficients is used for temperature drift design, so that the optical system can still achieve stable and clear imaging without loss of focus or blurring within a temperature range of -20℃ to +50℃.

[0038] In some embodiments, the first to the thirteenth lenses are all spherical lenses.

[0039] In the above technical solution, all lens surfaces are spherical lenses, which reduces lens costs.

[0040] In some embodiments, the third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, and tenth lens are made of glass.

[0041] The image-side surface of the third lens and the object-side surface of the fourth lens are cemented together; forming a first cemented lens group. The image-side surface of the fifth lens and the object-side surface of the sixth lens are cemented together; forming a second cemented lens group.

[0042] The image-side surface of the seventh lens is cemented together with the object-side surface of the eighth lens, forming the third cemented lens group; the image-side surface of the ninth lens is cemented together with the object-side surface of the tenth lens, forming the fourth cemented lens group.

[0043] In the above technical solution, the lens shape is set with an approximately symmetrical structure, and the transverse aberration is well corrected, resulting in excellent correction of coma, distortion, and chromatic aberration of the entire system. The combination of a glass material with a large dispersion shift and an approximately symmetrical structure corrects the chromatic aberration of the optical system to a very small value. This better meets the chromatic aberration performance requirements under high resolution and small pixel size conditions.

[0044] In some embodiments, the lens satisfies the following condition:

[0045] -0.90 <f C1 / f C4 <-0.10; -0.80 <f C2 / f C3 <-0.20

[0046] In the formula, f C1 f C2 f C3 f C4 These are the focal lengths of the first cemented lens group, the second cemented lens group, the third cemented lens group, and the fourth cemented lens group, respectively.

[0047] In the above technical solution, the focal length of the cemented lens group, satisfying the aforementioned optical power allocation, can effectively correct the spherical aberration of the optical system, resulting in a smaller radius of confusion. Simultaneously, a rationally allocated optical power can significantly reduce the sensitivity of the optical system and improve its production yield.

[0048] In some embodiments, the lens satisfies the following condition:

[0049] f / DI>1.50; 2 <f / DL1<4

[0050] In the formula, DI is the diameter of the image plane imaging circle, and DL1 is the effective light transmission diameter of the first lens.

[0051] In the above technical solution, satisfying the aforementioned relationship between the focal length and imaging ring diameter of the optical system can effectively increase the image size of the optical system and enhance the image quality experience. Meeting the effective aperture requirement of the first lens allows for miniaturization of the optical system in the outer diameter direction.

[0052] In some embodiments, the lens satisfies the following condition:

[0053] Nd1>1.85; 20 <Vd1<40

[0054] Nd 12 >1.85; 26 <Vd 12 <46

[0055] In the formula, Nd1 is the refractive index of the first lens, and Vd1 is the Abbe coefficient of the first lens; Nd 12 Vd is the refractive index of the twelfth lens. 12 This is the Abbe coefficient for the twelfth lens.

[0056] In the above technical solution, using a high-refractive-index glass grade can effectively reduce the incident angle of the positive lens and correct the spherical aberration of the system. This results in smoother light deflection, reduced lens sensitivity, and improved system yield.

[0057] According to another aspect of the present invention, a machine vision device is provided, comprising a near-object distance line scan lens as described above; and

[0058] An image sensor is configured to receive images formed by the near-object distance line scan lens.

[0059] In the above technical solution, the advantages of the machine vision device rely on the near-object distance line scanning lens, which will not be elaborated here. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 This is a schematic diagram of the structure of an example 1 of a near-object distance line scanning lens according to the present invention;

[0062] Figure 2 This is a field curvature and distortion curve diagram of an example 1 of a near-object distance line scan lens according to the present invention;

[0063] Figure 3 This is an MTF curve of an example 1 of a near-object distance line scan lens according to the present invention;

[0064] Figure 4 This is a star map of an example 1 of a near-object distance line scan lens according to the present invention;

[0065] Figure 5 This is a chromatic aberration diagram of an example 1 of a near-object distance line scan lens according to the present invention;

[0066] Figure 6 This is a schematic diagram of the structure of a near-object distance line scan lens example 2 of the present invention;

[0067] Figure 7 This is a field curvature and distortion curve diagram of an example 2 of a near-object distance line scan lens according to the present invention;

[0068] Figure 8 This is an MTF curve of an example 2 of a near-object distance line scan lens according to the present invention;

[0069] Figure 9 This is a star map of an example 2 of a near-object distance line scan lens according to the present invention;

[0070] Figure 10 This is a chromatic aberration diagram of an example 2 of a near-object distance line scan lens according to the present invention;

[0071] Figure 11 This is a schematic diagram of the structure of a near-object distance line scan lens, example 3, according to the present invention;

[0072] Figure 12 This is a field curvature and distortion curve diagram of an example 3 of a near-object distance line scan lens according to the present invention;

[0073] Figure 13 This is an MTF curve of an example 3 of a near-object distance line scan lens according to the present invention;

[0074] Figure 14 This is a star map of Example 3 of a near-object distance line scan lens of the present invention;

[0075] Figure 15 This is a chromatic aberration diagram of an example 3 of a near-object distance line scan lens according to the present invention;

[0076] Figure 16 This is a schematic diagram of the structure of an example 4 of a near-object distance line scanning lens according to the present invention;

[0077] Figure 17 This is a field curvature and distortion curve diagram of an example 4 of a near-object distance line scan lens according to the present invention;

[0078] Figure 18 This is the MTF curve of Example 4 of a near-object distance line scan lens of the present invention;

[0079] Figure 19 This is a star map of Example 4 of a near-object distance line scan lens of the present invention;

[0080] Figure 20 This is a chromatic aberration diagram of Example 4 of a near-object distance line scan lens of the present invention;

[0081] Figure 21 This is a schematic diagram of the structure of an example 5 of the machine vision device of the present invention;

[0082] Figure 22 This is a schematic diagram of the structure of the present invention, which decomposes the lens into two parts based on the aperture position. Detailed Implementation

[0083] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0084] The purpose of this invention is to provide a near-object distance line scan lens and machine vision device with high optical performance. Embodiments according to the invention will now be described in detail with reference to the accompanying drawings.

[0085] Figure 1 , Figure 6 , Figure 11 , Figure 16 These are cross-sectional views of the near-object distance line scan lenses (optical systems) according to Examples 1 to 4. The near-object distance line scan lenses according to each example are used in industrial line scan cameras, including those with resolutions such as 2K, 4K, 8K, 16K, 20K, or higher, and industrial line scan cameras with interchangeable lenses. In each cross-sectional view, the left side is the object-side OBJ and the right side is the image-side IMA. In each cross-sectional view, Gij represents the i-th lens unit. ST represents the aperture stop (fixed aperture stop or visible aperture stop). IMA represents the image plane, and when the near-object distance line scan lenses 1 to 4 according to each example are used in 2K, 4K, 8K, 16K, or other industrial line scan cameras and industrial line scan cameras with interchangeable lenses, solid-state imaging elements (photoelectric conversion elements), such as linear CMOS image sensors or linear CCD image sensors, are arranged on the image plane IMA.

[0086] The following describes the characteristic structure and conditions of a near-object distance line scan lens using various examples. A near-object distance line scan lens consists of 13 elements in 9 groups, with an approximately symmetrical structure before and after the aperture stop. There are two groups of cemented doublets before the aperture stop and two groups of cemented doublets after the aperture stop. The first group of cemented doublets before and after the aperture stop is symmetrical in shape, and the second group of cemented doublets has the same shape, both being combinations of positive and negative film. Please refer to... Figure 22The lens is divided into two parts at the aperture stop position. The front lens group is installed sequentially from front to back, and the rear lens group is installed sequentially from back to front. The aperture stop component is mounted on the rear element frame. The front and rear elements are connected by an AA (aperture assembly) joint, which facilitates assembly. Light rays converge through the first and second lenses, diverge through the third and fourth lenses, and finally converge on the image plane after passing through the last lens. The light rays climb the lens in a repeated spiral motion, thus correcting field curvature and astigmatism. This results in a relatively small field curvature for the entire system, meeting practical application requirements.

[0087] According to the examples, the near-object distance line scan lenses, in order from the object side to the image side, include:

[0088] First lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, thirteenth lens L13, G3 protective plate, aperture ST;

[0089] Among them, the first lens L1 has positive refractive power, with a convex object-side surface and a concave image-side surface; the second lens L2 has positive refractive power, with a convex object-side surface and a convex image-side surface; the third lens L3 has positive refractive power, with a convex object-side surface and a convex image-side surface; the fourth lens L4 has negative refractive power, with a concave object-side surface and a concave image-side surface; the fifth lens L5 has negative refractive power, with a concave object-side surface and a concave image-side surface; the sixth lens L6 has positive refractive power, with a convex object-side surface and a convex image-side surface; and the seventh lens L7 has positive refractive power, with a convex object-side surface and a concave image-side surface. The first lens has a convex surface, and the image side is also convex; the eighth lens L8 has negative refractive power, and both the object side and image side are concave; the ninth lens L8 has positive refractive power, and both the object side and image side are convex; the tenth lens L10 has negative refractive power, and both the object side and image side are concave; the eleventh lens L11 has negative refractive power, and both the object side and image side are concave; the twelfth lens L12 has positive refractive power, and both the object side and image side are concave; the thirteenth lens L13 has positive refractive power, and both the object side and image side are convex.

[0090] Among them, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, and the tenth lens L10 are made of glass; the image-side surface of the third lens L3 and the object-side surface of the fourth lens L4 are cemented together to form the first cemented lens group C1; the image-side surface of the fifth lens L5 and the object-side surface of the sixth lens L6 are cemented together to form the second cemented lens group C2; the image-side surface of the seventh lens L7 and the object-side surface of the eighth lens L8 are cemented together to form the third cemented lens group C3; and the image-side surface of the ninth lens L9 and the object-side surface of the tenth lens L10 are cemented together to form the fourth cemented lens group C4.

[0091] Among them, the first lens L1 to the thirteenth lens L13 are all spherical lenses.

[0092] According to each example, the near-object distance line scan lens can satisfy at least one of the following setting conditions 1) to 6):

[0093] 1) 350mm <WD<440mm;1.50<DW / DI<2.50;

[0094] 2.90<|f G1 / f|<5.10; 0.10<|f G2 / f|<1.90

[0095] 2) 4.80 <DS / T 12 <6.70

[0096] 3) The third lens is made of glass material with a negative refractive index temperature coefficient dn / dT; the fourth lens is made of glass material with a positive refractive index temperature coefficient dn / dT.

[0097] 4)-0.90 <f C1 / f C4 <-0.10; -0.80 <f C2 / f C3 <-0.20

[0098] 5) f / DI>1.50; 2 <f / DL1<4

[0099] 6) Nd1>1.85; 20 <Vd1<40;Nd 12 >1.85; 26 <Vd 12 <46

[0100] In the above conditions, WD is the working object distance of the lens, DW is the diameter of the object-side observation field of view of the lens, DI is the diameter of the image-side imaging circle, and f is the focal length of the lens. G1 f is the focal length of the first lens unit. G2 DS is the focal length of the second lens unit; DS is the aperture diameter when the lens passes through F4; T 12 f is the core thickness of the seventh lens; C1 f C2 f C3 f C4 DL1 represents the focal lengths of the first, second, third, and fourth cemented lens groups, respectively; Nd1 is the effective light-transmitting diameter of the first lens; Nd1 is the refractive index of the first lens; and Vd1 is the Abbe coefficient of the first lens. 12 Vd is the refractive index of the twelfth lens. 12 This is the Abbe coefficient for the twelfth lens.

[0101] Condition 1) defines the working object distance, field of view, image plane size, and focal lengths of the first and second lens units for the line scan lens. This design achieves the optimal working distance of 390mm (closest object distance 390mm) and a magnification of -0.5x by setting the closest object distance to 350mm and the farthest object distance to 440mm, as well as the ratio of the field of view diameter to the image circle. It also accommodates multiple object distances. Furthermore, the focal lengths of the first and second lens units are further limited to appropriately control the object-image conjugate distance, thereby meeting the design requirement of a large field of view at a specific working distance. If the four parameters exceed the upper limit, the optical system cannot be well applied to wide field-of-view and wide object distance applications, resulting in poor image quality. However, if they are below the lower limit, field curvature occurs, reducing the system's resolution. Moreover, to reliably obtain the effect of condition 1), it is preferable to set the values ​​of condition 1) to WD = 390mm; DW / DI = 2.0; |f G1 / f|=3.92;|f G2 / f|=0.87.

[0102] Condition 2) defines the ratio between the aperture diameter at F4 and the core thickness of the seventh lens (the first lens in the second lens unit). This design adjusts the aperture diameter as a variable, optimizing aberrations through multiple structures with different aperture diameters, rationally placing the aperture position, and setting a vignetting coefficient to optimize image quality, thus balancing image quality performance under different light levels. If the value is higher than the upper limit, the F-Number of the optical system is less than F4, increasing the light transmission of the optical system and increasing the lens's overall size. However, if the value is lower than the lower limit, the maximum light transmission that the optical system can support decreases, which is detrimental in low-light conditions. Furthermore, to reliably obtain the effect of condition 2), it is more preferable to set the value of condition 2) to DS / T. 12 =5.9.

[0103] Condition 3) defines the materials of the third and fourth lenses. A reasonable combination of glass grades with positive and negative dn / dT refractive index temperature coefficients is used for temperature drift design, ensuring that the optical system can maintain stable and clear imaging without defocusing or blurring within a temperature range of -20℃ to +50℃. Furthermore, to reliably achieve the effect of Condition 3), it is preferable to select third and fourth lenses with temperature coefficients of -5.9*10⁻⁶ / K and +2.7*10⁻⁶ / K, respectively.

[0104] Condition 4) defines the focal lengths of the first, second, third, and fourth cemented lens groups. This is beneficial for correcting spherical aberration in the optical system, resulting in a smaller spot radius. Simultaneously, a properly allocated optical power can significantly reduce the sensitivity of the optical system and improve its production yield. If the two parameter values ​​are higher than the upper limit, the optical power of the first and second cemented lens groups increases, the angle of incidence increases, and the lens groups become more sensitive. However, if they are lower than the lower limit, the optical power of the third and fourth lens groups increases, the angle of incidence increases, and the lens groups become more sensitive. Furthermore, to reliably obtain the effect of condition 4), it is more preferable to set the two parameter values ​​of condition 4) to f. C1 / f C4 = -0.51;

[0105] f C2 / f C3 = -0.68.

[0106] Condition 5) defines the relationship between the image plane size of the line scan lens, the effective light-transmitting diameter of the first lens, and the focal length. This is beneficial for effectively increasing the image size of the optical system and enhancing the image quality. Meeting the effective light-transmitting diameter of the first lens allows for miniaturization of the optical system in the outer diameter direction. If the ratio of the lens focal length to the image plane diameter is below the lower limit, the image captured by the optical system changes, and the image quality decreases. On the other hand, if the ratio of the lens focal length to the effective light-transmitting diameter of the first lens is above the upper limit, the focal length of the optical system increases, the effective aperture decreases, the magnification of the optical system increases, and the area that can detect objects decreases. However, if it is below the lower limit, the focal length of the optical system decreases, the effective aperture increases, the magnification of the optical system decreases, and the object resolution deteriorates. Furthermore, to reliably obtain the effect of condition 5), it is more preferable to set the two parameter values ​​of condition 5) to f / DI = 1.9 and f / DL1 = 3.06, respectively.

[0107] Condition 6) defines the glass parameters of the first and twelfth lenses. Using high-refractive-index glass effectively reduces the incident angle of the positive lens and corrects the spherical aberration of the system. This results in smoother light deflection, reduced lens sensitivity, and improved system yield. If the refractive indices of the two lenses are below the lower limit, the sensitivity of the optical system increases, which is detrimental to system yield. On the other hand, if the Abbe coefficients of the two lenses are above the upper limit, the residual chromatic aberration correction of the optical system is insufficient. However, if they are below the lower limit, the residual chromatic aberration correction of the optical system is overdone. Furthermore, to reliably obtain the effect of condition 6), it is more preferable to set the two parameter values ​​of condition 6) to Nd1 = 1.9; Vd1 = 31; Nd 12 =1.9; Vd 12 =35.

[0108] A detailed description of the zoom lens based on each example will now be given.

[0109] Please refer to the optical structure of Example 1. Figure 1 The specific parameters for Example 1 are shown in Table 1 below. In Example 1, the lens focal length f' = 156mm, aperture F = 4.0, field of view (FOV) = 15.3°, and total lens length (TTL) = 288mm. The conditional expressions are as follows:

[0110] 1) WD = 390mm; DW / DI = 2; |f G1 / f|=3.92;|f G2 / f|=0.87;

[0111] 2)DS / T 12 =5.88

[0112] 3) The third lens is made of glass material with a negative refractive index temperature coefficient dn / dT; the fourth lens is made of glass material with a positive refractive index temperature coefficient dn / dT.

[0113] 4)f C1 / f C4 =-0.51; f C2 / f C3 = -0.68

[0114] 5) f / DI = 1.9; f / DL1 = 3.1

[0115] 6) Nd1, Vd1, Nd 12 Vd 12 See table.

[0116] Table 1 Example 1 Parameter Table

[0117] surface type radius of curvature thickness Material Refractive index Dispersion coefficient focal length 1 First lens 106.800 4.8 Glass 1.9 31 195 2 260.400 15.8 3 Second lens 591.100 7.9 Glass 1.5 64 352 4 -264.400 9.7 5 Third lens 43.800 5.2 Glass 1.6 68 54 6 Fourth lens -119.000 2.2 Glass 1.8 67 -37 7 39.600 8.5 8 Fifth lens -76.900 5.2 Glass 1.6 34 -89 9 Sixth lens 246.300 7.7 Glass 1.8 50 112 10 -134.146 6.8 11 STO Infinity 3.0 12 Seventh Lens 62.700 4.6 Glass 1.7 51 45 13 Eighth lens -70.500 2.2 Glass 1.7 32 -45 14 55.200 1.3 15 Ninth Lens 108.800 4.2 Glass 1.9 21 39 16 Tenth Lens -54.900 2.7 Glass 1.7 31 -44 17 70.100 17.6 18 Eleventh Lens -46.600 5.1 Glass 1.8 25 -82 19 -159.200 1.2 20 The Twelfth Lens -99.900 4.5 Glass 1.9 35 127 21 -55.000 0.3 22 The Thirteenth Lens 225.400 4.7 Glass 1.8 52 149 23 -225.400 149.0 24 Protective glass Infinity 1.0 Glass 1.5 64 Infinity 25 Infinity 12.9 IMA Imaging surface Infinity

[0118] Please see Figure 2 Example 1 shows the field curvature distortion diagram of the optical system. The left diagram shows the field curvature, with the horizontal axis representing the field curvature value in millimeters and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the field curvature of this lens is within 0.2mm, and the maximum astigmatism occurs near a field of view of 0.85. The right diagram shows the relative optical distortion, with the horizontal axis representing the percentage of relative optical distortion in % and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the relative optical distortion of the lens is approximately 0.005%, which meets the requirements for high-precision measurement.

[0119] Please see Figure 3Example 1 shows the MTF curves, with the horizontal axis representing frequency (unit: line pairs) and the vertical axis representing MTF value (unit: none). The graph shows that the MTF curves for the large target surface are concentrated across all fields of view and are straight, with high MTF values ​​across low, medium, and high frequencies. The MTF in the center field of view is greater than 0.4 at 120 Lp / mm, and the MTF across the entire field of view is approximately greater than 0.25 at 120 Lp / mm. The MTF curves do not show collapse in the low-frequency region. This indicates good contour rendering of the lens, and the high-frequency MTF value is also greater than 0.25, indicating good detail. The MTF curves for all fields of view are nearly straight, maximizing the area enclosed by the horizontal axis within the entire field of view. The MTF curves for different fields of view are relatively concentrated, with the meridional and sagittal curves close together, indicating good consistency in overall image quality. This lens is well-suited for use with a 16K 5µm large target surface line scan lens, offering excellent image quality and high resolution.

[0120] Please see Figure 4 Example 1 shows the star pattern. As can be seen from the image, the star spot dispersion of this line scan lens is well optimized, with circular star shapes within the 0.7F field of view. The largest RMS star radius in each field of view is 3.448µm, smaller than the 5µm pixel size of the line scan camera sensor. The geometric mean square (GMS) radius of the central field of view and the 0.7F field of view is approximately the same as that of the sensor pixel, while the GMS radius of the entire field of view is 17.815µm, approximately 3.5 times the pixel size. This meets the requirements for using a 16K 5µm large target area line scan lens, offering high resolution and good image quality.

[0121] Please see Figure 5 Example 1 shows a color difference diagram. The horizontal axis represents the color difference value in micrometers, and the vertical axis represents the normalized field of view in infinitesimal units. The vertical lines on the left and right sides represent the range of Ally's disk radius values. From the diagram, it can be seen that the maximum color difference of this lens in the entire field of view (425nm-675nm) is within ±1.5µm, which is 0.3 times the pixel size. This falls within the 675nm wavelength range and meets the requirement of being within 5µm pixel size. All other wavelengths are within the Ally's disk range. This optical system exhibits good color difference correction and high color reproduction.

[0122] Please refer to the optical structure of Example 2. Figure 6 The specific parameters for Example 2 are shown in Table 2 below. In Example 2, the lens focal length f' = 157mm, aperture F = 4.0, field of view (FOV) = 18.3°, and total lens length (TTL) = 288mm. The conditional expressions are as follows:

[0123] 1) WD = 390mm; DW / DI = 2; |f G1 / f|=4.04;|f G2 / f|=0.84;

[0124] 2)DS / T12 =5.82

[0125] 3) The third lens is made of glass material with a negative refractive index temperature coefficient dn / dT; the fourth lens is made of glass material with a positive refractive index temperature coefficient dn / dT.

[0126] 4)f C1 / f C4 =-0.55; f C2 / f C3 =-0.6

[0127] 5)f / DI=1.91; f / DL1=3.01;

[0128] 6) Nd1, Vd1, Nd 12 Vd 12 See table.

[0129] Table 2 Example 2 Parameter Table

[0130] surface type radius of curvature thickness Material Refractive index Dispersion coefficient focal length 1 First lens 108.700 4.9 Glass 1.9 31 197 2 268.200 16.7 3 Second lens 592.800 6.8 Glass 1.5 64 362 4 -274.200 11.0 5 Third lens 43.400 5.2 Glass 1.6 68 54 6 Fourth lens -121.600 2.2 Glass 1.8 37 -37 7 39.400 8.7 8 Fifth lens -76.500 4.7 Glass 1.6 34 -90 9 Sixth lens 264.900 5.7 Glass 1.8 50 114 10 -133.031 8.7 11 STO Infinity 3.0 12 Seventh Lens 63.900 4.6 Glass 1.7 51 43 13 Eighth lens -64.500 2.2 Glass 1.7 32 -43 14 55.400 1.3 15 Ninth Lens 107.600 4.2 Glass 1.9 21 39 16 Tenth Lens -53.900 2.2 Glass 1.7 31 -44 17 71.000 18.1 18 Eleventh Lens -45.500 4.3 Glass 1.8 25 -81 19 -149.700 1.6 20 The Twelfth Lens -95.200 4.5 Glass 1.9 35 126 21 -53.500 0.3 22 The Thirteenth Lens 222.800 4.7 Glass 1.8 52 147 23 -222.800 149.0 24 Protective glass Infinity 1.0 Glass 1.5 64 Infinity 25 Infinity 12.5 IMA Imaging surface Infinity

[0131] Please see Figure 7 Example 2 shows the field curvature distortion diagram of the optical system. The left diagram shows the field curvature, with the horizontal axis representing the field curvature value in millimeters and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the field curvature of this lens is within 0.2mm, and the maximum astigmatism occurs near a field of view of 0.85. The right diagram shows the relative optical distortion, with the horizontal axis representing the percentage of relative optical distortion in % and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the relative optical distortion of the lens is approximately 0.005%, which meets the requirements for high-precision measurement.

[0132] Please see Figure 8 Example 2 shows the MTF curves, with the horizontal axis representing frequency (unit: line pairs) and the vertical axis representing MTF value (unit: none). The graph clearly shows that the MTF curves for the large target surface are concentrated across all fields of view and are straight, with high MTF values ​​across low, medium, and high frequencies. The MTF in the center field of view is greater than 0.4 at 120 Lp / mm, and the MTF across the entire field of view is approximately greater than 0.25 at 120 Lp / mm. The MTF curves do not exhibit collapse in the low-frequency region. This indicates good contour rendering of the lens, and the high-frequency MTF value is also greater than 0.25, indicating good detail. The MTF curves for all fields of view are nearly straight, maximizing the area enclosed by the horizontal axis within the entire field of view. The relatively concentrated MTF curves across different fields of view, with the meridional and sagittal curves close together, indicate good overall image quality consistency. This lens is well-suited for use with a 16K 5µm large target surface line scan lens, offering excellent image quality and high resolution.

[0133] Please see Figure 9 Example 2 shows the star pattern. As can be seen from the figure, the star spot dispersion of this line scan lens is well optimized, with circular star shapes within the 0.7F field of view. The largest RMS star radius in each field of view is 3.666µm, smaller than the 5µm pixel size of the line scan camera sensor. The geometric mean square (GMS) radius of the central field of view and the 0.7F field of view is approximately the same as that of the sensor pixel, while the GMS radius of the entire field of view is 19.866µm, approximately four times the pixel size. This meets the requirements for using a 16K 5µm large target area line scan lens, offering high resolution and good imaging quality.

[0134] Please see Figure 10 Example 2 shows a color difference diagram. The horizontal axis represents the color difference value in micrometers, and the vertical axis represents the normalized field of view in infinitesimal units. The vertical lines on the left and right sides represent the range of the Ally's disk radius. From the diagram, it can be seen that the maximum color difference of this lens in the entire field of view (425nm-675nm) is within ±1.5µm, which is 0.3 times the pixel size. This falls within the 675nm wavelength range and meets the requirement of being within 5µm pixel size. All other wavelengths are within the Ally's disk range. This optical system exhibits good color difference correction and high color reproduction.

[0135] Please refer to the optical structure of Example 3. Figure 11 The specific parameters for Example 3 are shown in Table 3 below. In Example 3, the lens focal length f' = 157mm, aperture F = 4.0, field of view (FOV) = 15.3°, and total lens length (TTL) = 288mm. The conditional expressions are as follows:

[0136] 1) WD = 390mm; DW / DI = 2; |f G1 / f|=4.05;|f G2 / f|=0.84;

[0137] 2)DS / T 12 =5.82

[0138] 3) The third lens is made of glass material with a negative refractive index temperature coefficient dn / dT; the fourth lens is made of glass material with a positive refractive index temperature coefficient dn / dT.

[0139] 4)f C1 / f C4 =-0.56; f C2 / f C3 =-0.6

[0140] 5) f / DI = 1.91; f / DL1 = 3;

[0141] 6) Nd1, Vd1, Nd 12 Vd 12 See table.

[0142] Table 3 Example 3 Parameter Table

[0143] surface type radius of curvature thickness Material Refractive index Dispersion coefficient focal length 1 First lens 108.700 4.9 Glass 1.9 31 197 2 267.100 18.2 3 Second lens 580.100 5.1 Glass 1.5 64 359 4 -274.900 11.0 5 Third lens 43.400 5.2 Glass 1.6 68 54 6 Fourth lens -121.800 2.2 Glass 1.8 37 -37 7 39.400 8.6 8 Fifth lens -76.700 4.8 Glass 1.6 34 -91 9 Sixth lens 276.200 5.4 Glass 1.8 50 116 10 -132.899 8.9 11 STO Infinity 3.0 12 Seventh Lens 63.950 4.6 Glass 1.7 51 43 13 Eighth lens -63.971 2.2 Glass 1.7 32 -43 14 55.449 1.3 15 Ninth Lens 107.646 4.2 Glass 1.9 21 39 16 Tenth Lens -53.784 2.2 Glass 1.7 31 -44 17 71.216 17.9 18 Eleventh Lens -45.300 4.3 Glass 1.8 25 -81 19 -149.600 1.7 20 The Twelfth Lens -95.100 4.5 Glass 1.9 35 126 21 -53.500 0.3 22 The Thirteenth Lens 223.000 4.7 Glass 1.8 52 147 23 -223.000 149.0 24 Protective glass Infinity 1.0 Glass 1.5 64 Infinity 25 Infinity 12.8 IMA Imaging surface Infinity

[0144] Please see Figure 12 Example 3 shows the field curvature distortion diagram of the optical system. The left diagram shows the field curvature, with the horizontal axis representing the field curvature value in millimeters and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the field curvature of this lens is within 0.2mm, and the maximum astigmatism occurs near a field of view of 0.85. The right diagram shows the relative optical distortion, with the horizontal axis representing the percentage of relative optical distortion in % and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the relative optical distortion of the lens is approximately 0.004%, which meets the requirements for high-precision measurement.

[0145] Please see Figure 13 Example 3 shows the MTF curves, with the horizontal axis representing frequency (unit: line pairs) and the vertical axis representing MTF value (unit: none). The graph shows that the MTF curves for the large target surface are concentrated across all fields of view and are straight, with high MTF values ​​across low, medium, and high frequencies. The MTF in the center field of view is greater than 0.4 at 120 Lp / mm, and the MTF across the entire field of view is approximately greater than 0.25 at 120 Lp / mm. The MTF curves do not show collapse in the low-frequency region. This indicates good contour rendering of the lens, and the high-frequency MTF value is also greater than 0.25, indicating good detail. The MTF curves for all fields of view are nearly straight, maximizing the area enclosed by the horizontal axis within the entire field of view. The MTF curves for different fields of view are relatively concentrated, with the meridional and sagittal curves close together, indicating good overall image quality consistency. This lens is well-suited for use with a 16K 5µm large target surface line scan lens, offering excellent imaging quality and high resolution.

[0146] Please see Figure 14 Example 3 shows the star pattern. As can be seen from the figure, the star spot dispersion of this line scan lens is well optimized, with circular star shapes within the 0.7F field of view. The largest RMS star radius in each field of view is 3.677µm, smaller than the 5µm pixel size of the line scan camera sensor. The geometric mean square (GMS) radius of the central field of view and the 0.7F field of view is approximately the same as that of the sensor pixel, while the GMS radius of the entire field of view is 20.073µm, approximately four times the pixel size. This meets the requirements for using a 16K 5µm large target area line scan lens, offering high resolution and good imaging quality.

[0147] Please see Figure 15Example 3 shows a color difference diagram. The horizontal axis represents the color difference value in micrometers, and the vertical axis represents the normalized field of view in infinitesimal units. The vertical lines on the left and right sides represent the range of Ally's disk radius values. From the diagram, it can be seen that the maximum color difference of this lens in the entire field of view (425nm-675nm) is within ±1.5µm, which is 0.3 times the pixel size. This falls within the 675nm wavelength range and meets the requirement of being within 5µm pixel size. All other wavelengths are within the Ally's disk range. This optical system exhibits good color difference correction and high color reproduction.

[0148] Please refer to the optical structure of Example 4. Figure 16 The specific parameters for Example 4 are shown in Table 4 below. In Example 4, the lens focal length f' = 157mm, aperture F = 4.0, field of view (FOV) = 18.3°, and total lens length (TTL) = 288mm. The conditions are as follows:

[0149] 1) WD = 390mm; DW / DI = 2; |f G1 / f|=4.07;|f G2 / f|=0.84;

[0150] 2)DS / T 12 =5.82

[0151] 3) The third lens is made of glass material with a negative refractive index temperature coefficient dn / dT; the fourth lens is made of glass material with a positive refractive index temperature coefficient dn / dT.

[0152] 4)f C1 / f C4 =-0.56; f C2 / f C3 = -0.59;

[0153] 5) f / DI = 1.91; f / DL1 = 3;

[0154] 6) Nd1, Vd1, Nd 12 Vd 12 See table.

[0155] Table 4 Example 4 Parameter Table

[0156]

[0157]

[0158] Please see Figure 17Example 4 shows the field curvature distortion diagram of the optical system. The left diagram shows the field curvature, with the horizontal axis representing the field curvature value in millimeters and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the field curvature of this lens is within 0.2mm, and the maximum astigmatism occurs near a field of view of 0.85. The right diagram shows the relative optical distortion, with the horizontal axis representing the percentage of relative optical distortion in % and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the relative optical distortion of the lens is approximately 0.004%, which meets the requirements for high-precision measurement.

[0159] Please see Figure 18 Example 4 shows the MTF curves, with the horizontal axis representing frequency in line pairs and the vertical axis representing MTF values ​​(units not specified). The graph shows that the MTF curves for the large target surface are concentrated across all fields of view and are straight, with high MTF values ​​across low, medium, and high frequencies. The MTF in the center field of view is greater than 0.4 at 120 Lp / mm, and the MTF across the entire field of view is approximately greater than 0.25 at 120 Lp / mm. The MTF curves do not show collapse in the low-frequency region. This indicates good contour rendering of the lens, and the high-frequency MTF value is also greater than 0.25, indicating good detail. The MTF curves for all fields of view are nearly straight, maximizing the area enclosed by the horizontal axis within the entire field of view. The MTF curves for different fields of view are relatively concentrated, with the meridional and sagittal curves close together, indicating good overall image quality consistency. This lens is well-suited for use with a 16K 5µm large target surface line scan lens, offering excellent image quality and high resolution.

[0160] Please see Figure 19 Example 4 shows the star pattern. As can be seen from the figure, the star spot dispersion of this line scan lens is well optimized, with circular star shapes within the 0.7F field of view. The largest RMS star radius in each field of view is 3.671µm, smaller than the 5µm pixel size of the line scan camera sensor. The geometric mean square (GMS) radius of the central field of view and the 0.7F field of view is approximately the same as that of the sensor pixel, while the GMS radius of the entire field of view is 20.066µm, approximately four times the pixel size. This meets the requirements for using a 16K 5µm large target area line scan lens, offering high resolution and good imaging quality.

[0161] Please see Figure 20 Example 4 shows a color difference diagram. The horizontal axis represents the color difference value in micrometers, and the vertical axis represents the normalized field of view in infinitesimal units. The vertical lines on the left and right sides represent the range of the Ally's disk radius. From the diagram, it can be seen that the maximum color difference of this lens in the entire field of view (425nm-675nm) is within ±1.3µm, which is 0.3 times the pixel size. This falls within the 675nm wavelength range and meets the requirement of being within 5µm pixel size. All other wavelengths are within the Ally's disk range. This optical system exhibits good color difference correction and high color reproduction.

[0162] Based on Examples 1 to 4, this case has the following advantages:

[0163] 1. The optimal working distance is set to a near object distance of 390mm, with the system magnification controlled at -0.5x, while also considering imaging at both the closest object distance of 350mm and the farthest object distance of 440mm. Simultaneously, the object-image conjugate distance is appropriately controlled to achieve the design requirement of a large field of view at a specific working distance.

[0164] 2. Large target surfaces are prone to low resolution and poor analytical power. By rationally allocating the optical power of each lens, using 13 optical lenses and 22 radii of curvature, and correcting the spherical aberration of the system, the lens resolution reaches 20K resolution level, which can fully support the use of large target surface line scan cameras with a resolution of 16K and a pixel size of 5um.

[0165] 3. By adopting an approximately symmetrical structure to set the lens shape, the vertical aberration is well corrected, resulting in very good correction of coma, distortion, and chromatic aberration of the entire system.

[0166] 4. By setting multiple structures with different light-transmitting apertures to optimize aberrations, rationally placing the aperture stop position, and setting the vignetting coefficient to optimize imaging quality, the image quality performance under different light transmission conditions is balanced.

[0167] 5. By incorporating the influence of lens frame, camera mounting ring, and spacer on temperature drift, and by using a reasonable combination of glass grades with positive and negative dn / dT refractive index temperature coefficients, the optical system can still achieve stable and clear imaging without loss of focus or blurring within a temperature range of -20℃ to +50℃.

[0168] 6. By employing a combination of glass materials with significant dispersion shift and an approximately symmetrical structure, the chromatic aberration of the optical system is corrected to a very small value. This better meets the chromatic aberration performance requirements under high resolution and small pixel size conditions.

[0169] Example 5

[0170] For reference Figure 21 A description of a machine vision device A according to Example 5 of the present invention will be given. Figure 21 This is a schematic diagram of a machine vision device (industrial line scan camera) for a camera optics system, based on any of the near-object distance line scan lenses in Examples 1 to 4.

[0171] exist Figure 21In the figures, reference numeral A2 indicates the main body of the machine vision device, and reference numeral A1 indicates a camera optical system (interchangeable lens) including any of the near-object distance line scan lenses according to Examples 1 to 4. Reference numeral A3 indicates an image sensor (photoelectric conversion element) such as a linear array CMOS image sensor or a linear array CCD image sensor, which is built into the camera body A2 and receives light (the optical image formed by the camera optical system A1) from the camera optical system A1 and performs photoelectric conversion.

[0172] By using a near-object distance line scan lens according to any one of Examples 1 to 4 in a machine vision device such as a digital still camera, a machine vision device with a line scan lens having high optical performance can be obtained.

[0173] The examples provide machine vision devices with high optical performance.

[0174] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims will be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A near-object distance line scan lens, characterized in that, From the object side to the image side, the components are, in sequence, a first lens unit with positive refractive power, an aperture stop, and a second lens unit with positive refractive power; The first lens unit consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens in sequence from the object side to the image side; the second lens unit consists of a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens in sequence from the object side to the image side. The lens satisfies the following condition: 350mm <WD<440mm;1.50<DW / DI<2.50 2.90<|f G1 / f|<5.10;0.10<|f G2 / f|<1.90 In the formula, WD is the working object distance of the lens, DW is the diameter of the object-side observation field of view of the lens, DI is the diameter of the image-side imaging circle, and f is the focal length of the lens. G1 f is the focal length of the first lens unit. G2 This is the focal length of the second lens unit; The first lens has positive refractive power, with a convex object-side surface and a concave image-side surface; The second lens has positive refractive power, and the object-side surface is convex, as is the image-side surface; The third lens has positive refractive power, and the object side is convex, as is the image side; The fourth lens has negative refractive power, and the object side is concave, as is the image side; The fifth lens has negative refractive power, and the object side is concave, as is the image side; The sixth lens has positive refractive power, and the object-side surface is convex, as is the image-side surface; The seventh lens has positive refractive power, and the object-side surface is convex, as is the image-side surface; The eighth lens has negative refractive power, and the object side is concave, as is the image side; The ninth lens has positive diopter, and the object-side surface is convex, as is the image-side surface; The tenth lens has negative refractive power, and the object side is concave, as is the image side; The eleventh lens has negative refractive power, with a concave object side and a convex image side; The twelfth lens has positive refractive power, with a concave object side and a convex image side; The thirteenth lens has positive refractive power, and the object side and the image side are both convex.

2. A near-object distance line scan lens as described in claim 1, characterized in that, The lens satisfies the following condition: 4.80<DS / T 12 <6.70 In the formula, DS is the aperture diameter when the lens passes through F4, and T... 12 The core thickness of the seventh lens.

3. A near-object distance line scan lens as described in claim 1, characterized in that, The third lens is made of glass material with a negative refractive index temperature coefficient dn / dT; The fourth lens is made of glass material with a positive refractive index temperature coefficient dn / dT.

4. A near-object distance line scan lens as described in claim 1, characterized in that, The first to the thirteenth lenses are all spherical lenses.

5. A near-object distance line scan lens as described in claim 1, characterized in that, The third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth lenses are made of glass. The image-side surface of the third lens and the object-side surface of the fourth lens are cemented together to form a first cemented lens group; the image-side surface of the fifth lens and the object-side surface of the sixth lens are cemented together to form a second cemented lens group. The image-side surface of the seventh lens and the object-side surface of the eighth lens are cemented together to form a third cemented lens group; the image-side surface of the ninth lens and the object-side surface of the tenth lens are cemented together to form a fourth cemented lens group.

6. A near-object distance line scan lens as described in claim 5, characterized in that, The lens satisfies the following condition: -0.90<f C1 / f C4 <-0.10;-0.80<f C2 / f C3 <-0.20 In the formula, f C1 f C2 f C3 f C4 These are the focal lengths of the first cemented lens group, the second cemented lens group, the third cemented lens group, and the fourth cemented lens group, respectively.

7. A near-object distance line scan lens as described in claim 1, characterized in that, The lens satisfies the following condition: f / DI>1.50; 2 <f / DL1<4 In the formula, DI is the diameter of the image plane imaging circle, and DL1 is the effective light transmission diameter of the first lens.

8. A near-object distance line scan lens as described in claim 1, characterized in that, The lens satisfies the following condition: Nd1>1.85; 20 <Vd1<40 Nd 12 >1.85;26<Vd 12 <46 In the formula, Nd1 is the refractive index of the first lens, and Vd1 is the Abbe coefficient of the first lens; Nd 12 Vd is the refractive index of the twelfth lens. 12 This is the Abbe coefficient for the twelfth lens.

9. A machine vision device, characterized in that, A near-object distance linear scanning lens according to any one of claims 1-8; and An image sensor is configured to receive images formed by the near-object distance line scan lens.

Images