Near object distance line scanning lens and machine vision equipment

Abstract

The invention discloses a near object distance line scanning lens and machine vision equipment. Wherein the lens sequentially comprises a first lens unit with positive diopter, a diaphragm and a second lens unit with positive diopter from an object side to an image side; wherein 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 an object side to an 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 conditional expressions: 350 mmlt; wDlt; WDlt; the thickness is 440 mm; 1.50 lt, 1.50 lt; a DW / Dilt; 2.50, 2.50; 2.90 lt, 2.90 lt; fG1 / flt; 5.10, 5.7, 5.8; 0.10 lt, 0.10 lt; fG2 / flt; in the formula 1.90, WD is the working object distance of the lens, DW is the diameter range of the object side observation visual field of the lens, DI is the diameter of an image side imaging ring, f is the focal length of the lens, fG1 is the focal length of the first lens unit, and fG2 is the focal length of the second lens unit. The invention aims to provide a near-object-distance line scanning lens with high optical performance and machine vision equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of line scanning lenses, and in particular to a short-object-distance line scanning lens and a machine vision device. Background Art

[0002] With the continuous development of machine vision, large-target line scan lenses are widely used in various industries, especially in the lithium battery industry in the automotive market with huge demand. In each production process of lithium batteries: lithium battery appearance defect detection, dimensional accuracy detection, joint welding quality detection, battery cell internal detection and label quality detection, etc., automated detection equipment is indispensable. As a key link to ensure the manufacturing efficiency and quality of lithium batteries, the demand for large field of view and high-precision detection of machine vision continues to increase. The use of line scan lenses to collect and analyze images of lithium battery products, detect product defects, flaws and defects, and judge whether the product is qualified or not is of great significance in lithium battery production and testing. As a core component, the optical performance of the line scan lens directly affects the measurement accuracy and effect of the system. The existing lithium battery line scan inspection lenses cannot meet current needs and have at least one of the following disadvantages:

[0003] 1) Existing lithium battery line scan lenses are optimized for a single working distance, and the imaging quality at close and long object distances is poor, and they cannot be used at multiple object distances at the same time;

[0004] 2) The existing lithium battery line scan lens has a low resolution, the object boundary image is blurred during dimensional accuracy detection, the image has too many excessive pixels, the recognition accuracy is low, and the detection effect is poor;

[0005] 3) The existing lithium battery line scanning lens has a relatively large target surface distortion, which easily affects the measurement accuracy.

[0006] 4) The existing lithium battery line scan lenses have different resolution performances at different light levels, and the resolution may deteriorate at low light levels.

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

[0008] 6) Existing lithium battery line scan lenses have large chromatic aberration, poor color reproduction, and poor color performance. Summary of the invention

[0009] In view of this, the object of the present invention is to provide a short-distance line scanning lens and a machine vision device with high optical performance. The lens can solve at least one technical disadvantage mentioned in the background technology.

[0010] According to one aspect of the present invention, there is provided a close object distance line scanning lens, which comprises, from the object side to the image side, a first lens unit with positive refractive power, an aperture, and a second lens unit with positive refractive power;

[0011] The first lens unit includes, from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens; the second lens unit includes, from the object side to the image side, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens;

[0012] The lens satisfies the following conditional formula:

[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] Where WD is the working object distance of the lens, DW is the diameter range of the object side observation field of view of the lens, DI is the diameter of the image circle on the image side, f is the focal length of the lens, and f G1 is the focal length of the first lens unit, f G2 is the focal length of the second lens unit.

[0016] In the above technical solution, the best working distance of the lens is set to 390mm near the object distance, and the magnification of the system is controlled to -0.5 times, taking into account the imaging conditions of 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 requirements of a large field of view at a specific working distance.

[0017] In some embodiments, the first lens has positive refractive power, the object side surface is convex, and the image side surface is concave;

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

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

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

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

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

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

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

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

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

[0027] The eleventh lens has negative refractive power, the object side surface is concave, and the image side surface is convex;

[0028] The twelfth lens has positive refractive power, the object side surface is concave, and the image side surface is convex;

[0029] The thirteenth lens has positive refractive power, and its object side surface is convex and its image side surface is convex.

[0030] In the above technical solutions, large target surfaces are prone to low resolution and poor resolving power. In this case, by reasonably allocating the optical focal length of each lens and using 13 optical lenses, the resolution of the lens 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.

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

[0032] 4.80 <DS / T 12 <6.70

[0033] Where DS is the aperture diameter of the lens when it passes through F4, T 12 is the core thickness of the seventh lens.

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

[0035] In some embodiments, the third lens is made of 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, the temperature drift design is carried out by reasonably combining glass grades with positive and negative dn / dT refractive index temperature coefficients, so that the optical system can still produce stable and clear images without loss of focus and blur within the temperature range of -20℃ to +50℃.

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

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

[0040] In some embodiments, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, and the 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 glued to each other, forming a first glued lens group; the image side surface of the fifth lens and the object side surface of the sixth lens are glued to each other, forming a second glued lens group;

[0042] The image side surface of the seventh lens and the object side surface of the eighth lens are glued to each other, forming a third glued lens group; the image side surface of the ninth lens and the object side surface of the tenth lens are glued to each other, forming a fourth glued lens group.

[0043] In the above technical solution, the lens shape is set with an approximately symmetrical structure, and the vertical axis aberration is well corrected, so that the coma, distortion and chromatic aberration of the entire system are very well corrected. The chromatic aberration of the optical system is corrected to a very small value by using a glass material with a large dispersion offset and an approximately symmetrical structure. It can better meet the chromatic aberration performance under high resolution and small pixel size.

[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 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 satisfies the above optical power distribution, which can effectively correct the spherical aberration of the optical system, so that the diffuse spot radius of the optical system is at a smaller value. At the same time, the reasonably distributed optical power can greatly reduce the sensitivity of the optical system and improve the production yield of the optical system.

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

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

[0050] Where DI is the image circle diameter of the image plane, and DL1 is the effective light diameter of the first lens.

[0051] In the above technical solution, the focal length and imaging circle diameter of the optical system satisfy the above relationship, which can effectively increase the imaging screen size of the optical system and enhance the image quality experience of the optical system. The effective aperture of the first lens is satisfied, which can achieve the miniaturization size requirement 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] Where, Nd1 is the refractive index of the first lens, Vd1 is the Abbe coefficient of the first lens; Nd 12 is the refractive index of the twelfth lens, Vd 12 is the Abbe coefficient of the twelfth lens.

[0056] In the above technical solution, the use of high refractive index glass grades can effectively reduce the incident angle of the positive lens light and correct the spherical aberration of the system, so that the light deflection is gentle, the sensitivity of the lens is reduced, and the system yield is improved.

[0057] According to another aspect of the present invention, there is provided a machine vision device, according to the above-mentioned close object distance line scanning lens; and

[0058] An image sensor is configured to receive an image formed by the close object distance line scan lens.

[0059] In the above technical solution, the advantages of the machine vision device rely on the close object distance line scanning lens, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0061] Figure 1 It is a structural schematic diagram of Example 1 of a close object distance line scanning lens of the present invention;

[0062] Figure 2 is a field curvature and distortion curve diagram of Example 1 of a close object distance line scanning lens of the present invention;

[0063] Figure 3 is an MTF curve diagram of Example 1 of a close object distance line scanning lens of the present invention;

[0064] Figure 4 is a star point diagram of Example 1 of a close object distance line scanning lens of the present invention;

[0065] Figure 5 is a chromatic aberration diagram of Example 1 of a close object distance line scanning lens of the present invention;

[0066] Figure 6 It is a structural schematic diagram of Example 2 of a close object distance line scanning lens of the present invention;

[0067] Figure 7 is a field curvature and distortion curve diagram of Example 2 of a close object distance line scanning lens of the present invention;

[0068] Figure 8 is an MTF curve diagram of Example 2 of a close object distance line scanning lens of the present invention;

[0069] Fig. 9 is a star point diagram of Example 2 of a close object distance line scanning lens of the present invention;

[0070] Fig.10 is a chromatic aberration diagram of Example 2 of a close object distance line scanning lens of the present invention;

[0071] Fig.11 It is a structural schematic diagram of Example 3 of a close object distance line scanning lens of the present invention;

[0072] Fig.12 is a graph of field curvature and distortion of Example 3 of a close object distance line scanning lens of the present invention;

[0073] Fig.13 is an MTF curve diagram of Example 3 of a close object distance line scanning lens of the present invention;

[0074] Fig.14 is a star point diagram of Example 3 of a close object distance line scanning lens of the present invention;

[0075] Fig.15 is a chromatic aberration diagram of Example 3 of a close object distance line scanning lens of the present invention;

[0076] Fig.16 It is a structural schematic diagram of Example 4 of a close object distance line scanning lens of the present invention;

[0077] Fig.17 is a field curvature and distortion curve diagram of Example 4 of a close object distance line scanning lens of the present invention;

[0078] Fig.18 is an MTF curve diagram of Example 4 of a close object distance line scanning lens of the present invention;

[0079] Fig.19 is a star point diagram of Example 4 of a close object distance line scanning lens of the present invention;

[0080] Fig. 20 is a chromatic aberration diagram of Example 4 of a close object distance line scanning lens of the present invention;

[0081] Fig.21 is a structural schematic diagram of a machine vision device example 5 of the present invention;

[0082] Fig. 22 It is a schematic diagram of the structure of the present invention in which a lens is decomposed into two parts according to the aperture position. DETAILED DESCRIPTION

[0083] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

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

[0085] Figure 1 , Figure 6 , Fig.11 , Fig.16 They are cross-sectional views of the close object distance line scan lens (optical system) according to Examples 1 to 4, respectively. The close object distance line scan lens according to each example is used for industrial line scan cameras including industrial line scan cameras such as 2K, 4K, 8K, 16K, 20K or above 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 an aperture (fixed aperture or visible aperture). IMA represents an image plane, and when the close object distance line scan lens 1 to 4 according to each example is used for 2K, 4K, 8K, 16K or other industrial line scan cameras and industrial line scan cameras with interchangeable lenses, a solid-state imaging element (photoelectric conversion element) such as a linear array CMOS image sensor or a linear array CCD image sensor is arranged on the imaging plane IMA.

[0086] Below, the characteristic structure and conditions of the close object distance line scanning lens are described based on various examples. The close object distance line scanning lens is composed of 13 elements in 9 groups. The structure before and after the aperture is approximately symmetrical. There are two groups of double cemented lenses before the aperture, and two groups of double cemented lenses after the aperture. The shapes of the first group of cemented lenses before and after the aperture are symmetrical, and the shapes of the second group of cemented lenses are the same, both of which are positive and negative film combinations. Please refer to Fig. 22The lens is divided into two parts according to the aperture position. The front lens group is installed from front to back, and the rear lens group is installed from back to front. The aperture component is installed on the rear lens frame. The front and rear components are connected through AA, which has the advantage of easy assembly. Through the first and second lenses, the light converges, and the third and fourth transmitted light rays become divergent, and converge on the image plane through the last lens. The light climbs repeatedly in the spiral shape in the lens to correct the field curvature and astigmatism. The field curvature of the entire system is relatively small to meet the actual use needs.

[0087] The close object distance line scan lens according to various examples includes, in order from the object side to the image side:

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

[0089] Among them, the first lens L1 has positive refractive power, the object side surface is convex, and the image side surface is concave; the second lens L2 has positive refractive power, the object side surface is convex, and the image side surface is convex; the third lens L3 has positive refractive power, the object side surface is convex, and the image side surface is convex; the fourth lens L4 has negative refractive power, the object side surface is concave, and the image side surface is concave; the fifth lens L5 has negative refractive power, the object side surface is concave, and the image side surface is concave; the sixth lens L6 has positive refractive power, the object side surface is convex, and the image side surface is convex; the seventh lens L7 has positive refractive power, the object side surface is convex, and the image side surface is convex; The eighth lens L8 has negative refractive power, the object side surface is concave, and the image side surface is concave; the ninth lens L8 has positive refractive power, the object side surface is convex, and the image side surface is convex; the tenth lens L10 has negative refractive power, the object side surface is concave, and the image side surface is concave; the eleventh lens L11 has negative refractive power, the object side surface is concave, and the image side surface is convex; the twelfth lens L12 has positive refractive power, the object side surface is concave, and the image side surface is convex; the thirteenth lens L13 has positive refractive power, the object side surface is convex, and the image side surface is 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 a 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 a 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 a third cemented lens group C3; the image side surface of the ninth lens L9 and the object side surface of the tenth lens L10 are cemented together to form a fourth cemented lens group C4.

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

[0092] The close object distance line scan lens according to each example may 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 conditional formula, WD is the working object distance of the lens, DW is the diameter range of the object side observation field of view of the lens, DI is the diameter of the image circle on the image side, f is the focal length of the lens, and f G1 is the focal length of the first lens unit, f G2 is the focal length of the second lens unit; DS is the aperture diameter of the lens when it passes through F4, T 12 is the core thickness of the seventh lens; f C1 、f C2 、f C3 、f C4 are the focal lengths of the first, second, third and fourth cemented lens groups respectively; DL1 is the effective light diameter of the first lens; Nd1 is the refractive index of the first lens, Vd1 is the Abbe coefficient of the first lens; Nd 12 is the refractive index of the twelfth lens, Vd 12 is the Abbe coefficient of the twelfth lens.

[0101] Conditional formula 1) defines the working object distance, field of view, imaging surface size, and focal length of the first lens unit and the second lens unit of the line scanning lens. In this case, 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 imaging circle, the requirements of the optimal working distance being 390mm for the closest object distance and the system magnification being controlled to -0.5 times are met, and multiple object distances can also be used. At the same time, the focal lengths of the first lens unit and the second lens unit are further limited to appropriately control the object-image conjugate distance, thereby achieving the design requirements of a large field of view at a specific working distance. If the four parameters are higher than the upper limit, the optical system cannot be well applied to occasions with a large field of view and wide object distance, and the imaging quality of the optical system deteriorates. However, if the four parameters are lower than the lower limit, the optical system produces field curvature, thereby reducing the resolution of the optical system. In addition, in order to reliably obtain the effect of conditional formula 1), it is more preferred to set the value of conditional formula 1) to WD = 390mm; DW / DI = 2.0; |f G1 / f|=3.92;|f G2 / f|=0.87.

[0102] Conditional equation 2) defines the ratio between the aperture diameter when the lens passes through F4 and the core thickness of the seventh lens (the first lens of the second lens unit). In this case, the aperture is adjusted as a variable, and the aberration is optimized by setting multiple structures with different apertures, the aperture position is reasonably placed, and the vignetting coefficient is set to optimize the imaging quality, so as to balance the image quality performance under different light transmission. If it is higher than the upper limit, the F-Number value of the optical system is less than F4, the light transmission of the optical system increases, and the outer dimensions of the lens increase. However, if it is lower than the lower limit, the maximum light transmission that the optical system can support becomes smaller, which is not conducive to occasions with dim light. In addition, in order to reliably obtain the effect of conditional equation 2), it is more preferred to set the value of conditional equation 2) to DS / T 12 =5.9.

[0103] Conditional formula 3) defines the materials of the third lens and the fourth lens. The temperature drift design is performed by using glass grades with positive and negative values ​​of dn / dT refractive index temperature coefficients in a reasonable combination, so that the optical system can still stably and clearly image without defocusing and blurring in the temperature range of -20℃ to +50℃. In addition, in order to reliably obtain the effect of conditional formula 3), it is more preferred that the temperature coefficients of the third lens and the fourth lens are -5.9*10-6 / K and +2.7*10-6 / K respectively.

[0104] Conditional formula (4) defines 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. It is beneficial to correct the spherical aberration of the optical system so that the radius of the diffuse spot of the optical system is at a smaller value. At the same time, the reasonably distributed optical focal length can greatly reduce the sensitivity of the optical system and improve the production yield of the optical system. If the two parameter values ​​are higher than the upper limit value, the optical focal length of the first and second cemented lens groups increases, the incident angle increases, and the lens group becomes sensitive. However, if it is lower than the lower limit value, the optical focal length of the third and fourth lens groups increases, the incident angle increases, and the lens group becomes sensitive. In addition, in order to reliably obtain the effect of conditional formula (4), it is more preferred to set the two parameter values ​​of conditional formula (4) to f respectively. C1 / f C4 =-0.51;

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

[0106] Conditional formula 5) defines the relationship between the image plane size of the line scan lens, the effective aperture of the first lens and the focal length. It is beneficial to effectively increase the size of the optical system imaging screen and enhance the image quality experience of the optical system. By meeting the effective aperture of the first lens, the miniaturization size requirements of the optical system in the outer diameter direction can be achieved. If the ratio of the focal length of the lens to the diameter of the image plane imaging circle is lower than the lower limit, the shooting picture of the optical system changes and the image quality becomes lower. On the other hand, if the ratio of the focal length of the lens to the effective aperture of the first lens is higher than 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 of ​​the detectable object becomes smaller. However, if it is lower than 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 ability deteriorates. In addition, in order to reliably obtain the effect of conditional formula 5), ​​it is more preferred to set the two parameter values ​​of conditional formula 5) to f / DI=1.9; f / DL1=3.06 respectively.

[0107] Conditional equation 6) defines the glass parameters of the first lens and the twelfth lens materials. The use of high refractive index glass grades can effectively reduce the incident angle of the positive lens light and correct the spherical aberration of the system. As a result, the light is deflected smoothly, the sensitivity of the lens is reduced, and the system yield is improved. If the refractive index of the two lenses is lower than the lower limit, the sensitivity of the optical system increases, which is not conducive to the system yield. On the other hand, if the Abbe coefficients of the two lenses are higher than the upper limit, the residual chromatic aberration of the optical system is insufficiently corrected. However, if it is lower than the lower limit, the residual chromatic aberration of the optical system is over-corrected. In addition, in order to reliably obtain the effect of conditional equation 6), it is more preferred to set the two parameter values ​​of conditional equation 6) to Nd1=1.9; Vd1=31; Nd 12 =1.9; Vd 12 =35.

[0108] A detailed description will now be given of zoom lenses according to various examples.

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

[0110] 1) WD = 390 mm; 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 Parameters

[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 The third lens 43.800 5.2 Glass 1.6 68 54 6 The 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 The 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 The eighth lens -70.500 2.2 Glass 1.7 32 -45 14 55.200 1.3 15 The 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 Twelfth lens -99.900 4.5 Glass 1.9 35 127 21 -55.000 0.3 22 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] See also Figure 2 , the field curvature distortion diagram of the optical system of Example 1, the left figure is the field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the field curvature of the lens is within 0.2mm, and the maximum astigmatism is near the 0.85 field of view. The right figure is the optical relative distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the relative optical distortion of the lens is about 0.005%, which can meet the requirements for high-precision measurement.

[0119] See also Figure 3, the MTF curve of Example 1, the horizontal axis is frequency, the unit is line pair. The vertical axis is the MTF value, the unit is none. As can be seen from the figure, the MTF curves of each field of view of the large target surface are concentrated, and the curves are straight, and the medium, low and high frequency MTFs all have high MTF values. The MTF of the central field of view is greater than 0.4 at 120Lp / mm, and the MTF of the full field of view is greater than about 0.25 at 120Lp / mm. The MTF curve does not collapse in the low-frequency area. The outline of the lens is good, and the high-frequency MTF value is also greater than 0.25, indicating that the details are good. The MTF curves of all fields of view are straight and close to straight lines, and the area of ​​the city surrounded by the horizontal axis within the full field of view has been relatively maximized. The MTF curves of different fields of view are relatively concentrated, and the meridian curve and the sagittal curve are close, indicating that the overall image quality consistency is relatively good. It can be well matched with the 16K5um large target line scanning lens, with excellent imaging quality and high resolution.

[0120] See also Figure 4 , the star point diagram of Example 1. It can be seen from the figure that the star point diffusion spot of the line scan lens is well optimized, and the star point shape within the field of view within 0.7F is circular. The maximum RMS star point radius of each field of view is 3.448um, which is smaller than the 5um pixel size of the line scan camera sensor. The geometric root mean square radius in the center field of view and the 0.7F field of view is roughly the same as the sensor pixel, and the geometric root mean square radius of the full field of view is 17.815um, which is roughly 3.5 times the pixel size. It can meet the use requirements of 16K5um large target line scan lenses, with high resolution and good imaging quality.

[0121] See also Figure 5 , the chromatic aberration diagram of Example 1, the horizontal axis is the chromatic aberration value, the unit is micrometer; the vertical axis is the normalized field of view, the unit is infinite. The vertical lines on the left and right sides are the range of the radius of the Airy disk. It can be concluded from the figure that the maximum chromatic aberration of the lens in the entire field of view of 425nm-675nm is within plus or minus 1.5um, 0.3 times the pixel size, belongs to the 675nm wavelength, meets the 5um pixel size, and the remaining wavelengths are within the Airy disk. The optical system has good chromatic aberration correction and high color reproduction.

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

[0123] 1) WD = 390 mm; 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 Parameters

[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 The third lens 43.400 5.2 Glass 1.6 68 54 6 The 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 The 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 The eighth lens -64.500 2.2 Glass 1.7 32 -43 14 55.400 1.3 15 The 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 Twelfth lens -95.200 4.5 Glass 1.9 35 126 21 -53.500 0.3 22 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] See also Figure 7 , the field curvature distortion diagram of the optical system of Example 2, the left figure is the field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the field curvature of the lens is within 0.2mm, and the maximum astigmatism is near the 0.85 field of view. The right figure is the optical relative distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the relative optical distortion of the lens is about 0.005%, which can meet the requirements for high-precision measurement.

[0132] See also Figure 8 , the MTF curve of Example 2, the horizontal axis is frequency, the unit is line pair. The vertical axis is the MTF value, the unit is none. It can be intuitively concluded from the figure: the MTF curves of each field of view of the large target surface are concentrated, and the curves are straight, and the medium, low and high frequency MTFs all have high MTF values. The MTF of the central field of view is greater than 0.4 at 120Lp / mm, and the MTF of the full field of view is greater than about 0.25 at 120Lp / mm. The MTF curve does not collapse in the low-frequency area. The outline of the lens is good, and the high-frequency MTF value is also greater than 0.25, indicating that the details are well performed. The MTF curves of all fields of view are straight and close to straight lines, and the area of ​​the city surrounded by the horizontal axis within the full field of view has been relatively maximized. The MTF curves of different fields of view are relatively concentrated, and the meridian curve and the sagittal curve are close, indicating that the overall image quality consistency is relatively good. It can be well matched with the 16K5um large target line scanning lens, with excellent imaging quality and high resolution.

[0133] See also Fig. 9 , the star point diagram of Example 2. It can be seen from the figure that the star point diffusion spot of the line scan lens is well optimized, and the star point shape within the field of view within 0.7F is circular. The maximum RMS star point radius of each field of view is 3.666um, which is smaller than the 5um pixel size of the line scan camera sensor. The geometric root mean square radius in the center field of view and the 0.7F field of view is roughly the same as the sensor pixel, and the geometric root mean square radius of the full field of view is 19.866um, which is roughly 4 times the pixel size. It can meet the use requirements of 16K5um large target line scan lenses, with high resolution and good imaging quality.

[0134] See also Fig.10 , the chromatic aberration diagram of Example 2, the horizontal axis is the chromatic aberration value, the unit is micrometer; the vertical axis is the normalized field of view, the unit is infinite. The vertical lines on the left and right sides are the range of the radius of the Airy disk. It can be concluded from the figure that the maximum chromatic aberration of the lens in the entire field of view of 425nm-675nm is within plus or minus 1.5um, 0.3 times the pixel size, belongs to the 675nm wavelength, meets the 5um pixel size, and the remaining wavelengths are within the Airy disk. The optical system has good chromatic aberration correction and high color reproduction.

[0135] For the optical structure of Example 3, please refer to Fig.11 , the specific parameters of Example 3 are shown in Table 3 below. In Example 3, the focal length of the lens f'=157mm, the aperture F=4.0, the field of view angle FOV=15.3°, and the total length of the lens TTL=288mm. The conditional formula is as follows:

[0136] 1) WD = 390 mm; 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 Parameters

[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 The third lens 43.400 5.2 Glass 1.6 68 54 6 The 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 The 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 The eighth lens -63.971 2.2 Glass 1.7 32 -43 14 55.449 1.3 15 The 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 Twelfth lens -95.100 4.5 Glass 1.9 35 126 21 -53.500 0.3 22 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] See also Fig.12 , the field curvature distortion diagram of the optical system of Example 3, the left figure is the field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the field curvature of the lens is within 0.2mm, and the maximum astigmatism is near the 0.85 field of view. The right figure is the optical relative distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the relative optical distortion of the lens is about 0.004%, which can meet the requirements for high-precision measurement.

[0145] See also Fig.13 , the MTF curve of Example 3, the horizontal axis is frequency, the unit is line pair. The vertical axis is the MTF value, the unit is none. As can be seen from the figure, the MTF curves of each field of view of the large target surface are concentrated, and the curves are straight, and the medium, low and high frequency MTFs all have high MTF values. The MTF of the central field of view is greater than 0.4 at 120Lp / mm, and the MTF of the full field of view is greater than about 0.25 at 120Lp / mm. The MTF curve does not collapse in the low-frequency area. The outline of the lens is good, and the high-frequency MTF value is also greater than 0.25, indicating that the details are well performed. The MTF curves of all fields of view are straight and close to straight lines, and the area of ​​the city surrounded by the horizontal axis within the full field of view has been relatively maximized. The MTF curves of different fields of view are relatively concentrated, and the meridian curve and the sagittal curve are close, indicating that the overall image quality consistency is relatively good. It can be well matched with the 16K5um large target line scanning lens, with excellent imaging quality and high resolution.

[0146] See also Fig.14 , the star point diagram of Example 3. It can be seen from the figure that the star point diffusion spot of the line scan lens is well optimized, and the star point shape within the field of view within 0.7F is circular. The maximum RMS star point radius of each field of view is 3.677um, which is smaller than the 5um pixel size of the line scan camera sensor. The geometric root mean square radius in the center field of view and the 0.7F field of view is roughly the same as the sensor pixel, and the geometric root mean square radius of the full field of view is 20.073um, which is roughly 4 times the pixel size. It can meet the use requirements of 16K5um large target line scan lenses, with high resolution and good imaging quality.

[0147] See also Fig.15, the chromatic aberration diagram of Example 3, the horizontal axis is the chromatic aberration value, the unit is micrometer; the vertical axis is the normalized field of view, the unit is infinite. The vertical lines on the left and right sides are the range of the radius of the Airy disk. It can be concluded from the figure that the maximum chromatic aberration of the lens in the entire field of view of 425nm-675nm is within plus or minus 1.5um, 0.3 times the pixel size, belongs to the 675nm wavelength, meets the 5um pixel size, and the remaining wavelengths are within the Airy disk. The optical system has good chromatic aberration correction and high color reproduction.

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

[0149] 1) WD = 390 mm; 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 Parameters

[0156]

[0157]

[0158] See also Fig.17, the field curvature distortion diagram of the optical system of Example 4, the left figure is the field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the field curvature of the lens is within 0.2mm, and the maximum astigmatism is near the 0.85 field of view. The right figure is the optical relative distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the relative optical distortion of the lens is about 0.004%, which can meet the requirements for high-precision measurement.

[0159] See also Fig.18 , the MTF curve of Example 4, the horizontal axis is frequency, the unit is line pair. The vertical axis is the MTF value, the unit is none. As can be seen from the figure, the MTF curves of each field of view of the large target surface are concentrated, and the curves are straight, and the medium, low and high frequency MTFs all have high MTF values. The MTF of the central field of view is greater than 0.4 at 120Lp / mm, and the MTF of the full field of view is greater than about 0.25 at 120Lp / mm. The MTF curve does not collapse in the low-frequency area. The surface of the lens has a good profile, and the high-frequency MTF value is also greater than 0.25, indicating that the details are well performed. The MTF curves of all fields of view are straight and close to straight lines, and the area of ​​the city surrounded by the horizontal axis within the full field of view has been relatively maximized. The MTF curves of different fields of view are relatively concentrated, and the meridian curve and the sagittal curve are close, indicating that the overall image quality consistency is relatively good. It can be well matched with the 16K5um large target line scanning lens, with excellent imaging quality and high resolution.

[0160] See also Fig.19 , the star point diagram of Example 4. It can be seen from the figure that the star point diffusion spot of the line scan lens is well optimized, and the star point shape within the field of view within 0.7F is circular. The maximum RMS star point radius of each field of view is 3.671um, which is smaller than the 5um pixel size of the line scan camera sensor. The geometric root mean square radius in the center field of view and the 0.7F field of view is roughly the same as the sensor pixel, and the geometric root mean square radius of the full field of view is 20.066um, which is roughly 4 times the pixel size. It can meet the use requirements of 16K5um large target line scan lenses, with high resolution and good imaging quality.

[0161] See also Fig. 20 , the chromatic aberration diagram of Example 4, the horizontal axis is the chromatic aberration value, the unit is micrometer; the vertical axis is the normalized field of view, the unit is infinite. The vertical lines on the left and right sides are the range of the radius of the Airy disk. It can be concluded from the figure that the maximum chromatic aberration of the lens in the entire field of view of 425nm-675nm is within plus or minus 1.3um, 0.3 times the pixel size, belongs to the 675nm wavelength, meets the 5um pixel size, and the remaining wavelengths are within the Airy disk. The optical system has good chromatic aberration correction and high color reproduction.

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

[0163] 1. The best working distance is set to 390mm for the closest object distance, and the system magnification is controlled to -0.5 times, taking into account the imaging conditions of 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 requirements of a large field of view at a specific working distance.

[0164] 2. Large target surfaces are prone to low resolution and poor resolving power. By reasonably allocating the optical power of each lens, using 13 optical lenses, 22 curvature radii, and correcting the spherical aberration of the system, the resolution of the lens 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. The lens shape is set with an approximately symmetrical structure, and the vertical axis aberration is well corrected, so that the coma, distortion and chromatic aberration of the entire system are very well corrected.

[0166] 4. Optimize aberrations by setting multiple structures with different apertures, reasonably place the aperture position, set the vignetting coefficient to optimize the imaging quality, and balance the image quality performance under different apertures.

[0167] 5. The influence of the frame, camera structure and spacer on temperature drift is introduced, and the glass grades with positive and negative dn / dT refractive index temperature coefficients are reasonably matched for temperature drift design, so that the optical system can still produce stable and clear images without loss of focus and blur within the temperature range of -20℃ to +50℃.

[0168] 6. Use glass materials with large dispersion offset and approximately symmetrical structure to correct the chromatic aberration of the optical system to a very small value. This can better meet the chromatic aberration performance under high resolution and small pixel size.

[0169] Example 5

[0170] Reference Fig.21 , a description will be given of a machine vision device A according to Example 5 of the present invention. Fig.21 1 is a schematic diagram of a machine vision device (industrial line scan camera) using any one of the close object distance line scan lenses according to Examples 1 to 4 for an imaging optical system.

[0171] exist Fig.21, reference numeral A2 denotes a machine vision device body, and reference numeral A1 denotes an imaging optical system (interchangeable lens) including any one of the close object distance line scan lenses according to Examples 1 to 4. Reference numeral A3 denotes 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 (optical image formed by the imaging optical system A1) from the imaging optical system A1 and performs photoelectric conversion.

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

[0173] Various examples may provide a machine vision device with high optical performance.

[0174] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A close object distance line scanning lens, characterized in that: From the object side to the image side, there are a first lens unit with positive refractive power, a stop, and a second lens unit with positive refractive power; The first lens unit includes, from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens; the second lens unit includes, from the object side to the image side, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens; The lens satisfies the following conditional formula: 350mm <WD<440mm;1.50<DW / DI<2.50 2.90<|f G1 / f|<5.10;0.10<|f G2 / f|<1.90 Where WD is the working object distance of the lens, DW is the diameter range of the object side observation field of view of the lens, DI is the diameter of the image circle on the image side, f is the focal length of the lens, and f G1 is the focal length of the first lens unit, f G2 is the focal length of the second lens unit.

2. The close object distance line scanning lens according to claim 1, characterized in that: The first lens has positive refractive power, the object side surface is convex, and the image side surface is concave; The second lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The third lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The fourth lens has negative refractive power, and its object side surface is concave, and its image side surface is concave; The fifth lens has negative refractive power, and its object side surface is concave, and its image side surface is concave; The sixth lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The seventh lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The eighth lens has negative refractive power, and its object side surface is concave, and its image side surface is concave; The ninth lens has positive refractive power, the object side surface is convex, and the image side surface is convex; The tenth lens has negative refractive power, and its object side surface is concave, and its image side surface is concave; The eleventh lens has negative refractive power, the object side surface is concave, and the image side surface is convex; The twelfth lens has positive refractive power, the object side surface is concave, and the image side surface is convex; The thirteenth lens has positive refractive power, and its object side surface is convex and its image side surface is convex.

3. A close object distance line scanning lens as claimed in claim 1 or 2, characterized in that: The lens satisfies the following conditional formula: 4.80<DS / T 12 <6.70 Where DS is the aperture diameter of the lens when it passes through F4, T 12 is the core thickness of the seventh lens.

4. A close object distance line scanning lens as claimed in claim 1 or 2, 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.

5. The close object distance line scanning lens according to claim 1 or 2, characterized in that: The first lens to the thirteenth lens are all spherical lenses.

6. A close object distance line scanning lens as claimed in claim 1 or 2, characterized in that: The third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are made of glass; The image side surface of the third lens and the object side surface of the fourth lens are glued together to form a first glued lens group; the image side surface of the fifth lens and the object side surface of the sixth lens are glued together to form a second glued lens group; The image side surface of the seventh lens and the object side surface of the eighth lens are glued together to form a third glued lens group; the image side surface of the ninth lens and the object side surface of the tenth lens are glued together to form a fourth glued lens group.

7. The close object distance line scanning lens according to claim 6, characterized in that: The lens satisfies the following conditional formula: -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 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.

8. The close object distance line scanning lens according to claim 1 or 2, characterized in that: The lens satisfies the following conditional formula: f / DI>1.50;2 <f / DL1<4 Where DI is the image circle diameter of the image plane, and DL1 is the effective light diameter of the first lens.

9. The close object distance line scanning lens according to claim 1 or 2, characterized in that: The lens satisfies the following conditional formula: Nd1>1.85; 20 <Vd1<40 Nd 12 >1.85;26<Vd 12 <46 Where, Nd1 is the refractive index of the first lens, Vd1 is the Abbe coefficient of the first lens; Nd 12 is the refractive index of the twelfth lens, Vd 12 is the Abbe coefficient of the twelfth lens.

10. A machine vision device, characterized in that: A close object distance line scanning lens according to any one of claims 1 to 9; and An image sensor is configured to receive an image formed by the close object distance line scan lens.

Images