A small industrial lens with large image area, low distortion and high resolution

Abstract

The present invention discloses a miniaturized industrial lens with large target surface, low distortion and high resolution, which comprises, in order from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a stop C, a sixth lens L6, a seventh lens L7 and an eighth lens L8, wherein the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 constitute a front lens group, the sixth lens L6, the seventh lens L7 and the eighth lens L8 constitute a rear lens group, the fourth lens L4 and the fifth lens L5 are closely connected to form a first cemented group; the sixth lens L6 and the seventh lens L7 are closely connected to form a second cemented group. The industrial lens has the performance of large target surface, low distortion and high resolution.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial optical lenses, and in particular relates to a miniaturized industrial lens with a large target surface, low distortion and high resolution. Background Art

[0002] Industrial lenses are important components in industrial automation systems. They play a key role in the field of intelligent manufacturing and are responsible for capturing image data. They are equivalent to the "eyes" of the machine, and their performance directly determines the effectiveness of the entire visual system.

[0003] Due to the particularity of the industrial environment, industrial lenses need to meet higher standards than ordinary lenses, such as larger imaging area, lower image distortion, clearer image quality and smaller size.

[0004] At present, industrial lenses still have certain shortcomings and defects, and there is a huge market demand for small industrial lenses that can provide a larger imaging range, smaller distortion, and higher clarity.

[0005] Therefore, developing an industrial lens that can fully meet the above requirements has become an urgent task to be solved. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a miniaturized industrial lens with a large target surface, low distortion and high resolution, so that the lens has the performance of a large target surface, a small volume, low distortion and high resolution.

[0007] To achieve the above-mentioned object, the present invention provides the following technical solution: a small-sized industrial lens with a large target surface, low distortion and high resolution, wherein the industrial lens comprises, in order from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a stop C, a sixth lens L6, a seventh lens L7 and an eighth lens L8, wherein the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 constitute a front lens group, and the sixth lens L6, the seventh lens L7 and the eighth lens L8 constitute a rear lens group, wherein the first lens L1, the third lens L3, the fourth lens L4, the seventh lens L7 and the eighth lens L8 have positive focal lengths, and the second lens L2, the fifth lens L5 and the sixth lens L6 have negative focal lengths;

[0008] The fourth lens L4 and the fifth lens L5 are closely connected to form a first cemented group; the sixth lens L6 and the seventh lens L7 are closely connected to form a second cemented group;

[0009] The total focal length of the optical system is f, and the effective focal length of the first cemented group is f G1 , the effective focal length of the second cemented group is f G2, the maximum field of view of the industrial lens is FOV, which satisfies the following relationship: 0.5≤|(f G1 ×f / f G2 )×tan(FOV / 4)|≤1.5; the effective focal length of the front lens is f u1 , the effective focal length of the rear lens is f u2 , f u1 、f u2 The following relationship is satisfied between |f u1 / f|≤1.6,|f u2 / f|≥0.7.

[0010] As a specific implementation, in the optical system, the first lens L1 is a biconvex positive lens; the second lens L2 is a biconcave negative lens; the third lens L3 is a positive meniscus lens with the convex surface facing the object; the fourth lens L4 is a biconvex positive lens or a positive meniscus lens with the convex surface facing the object; the fifth lens L5 is a biconcave negative lens or a negative meniscus lens with the convex surface facing the object; the sixth lens L6 is a negative meniscus lens with the convex surface facing the image; the seventh lens L7 is a positive meniscus lens with the convex surface facing the image; and the eighth lens L8 is a biconvex positive lens or a positive meniscus lens with the convex surface facing the image.

[0011] As a specific implementation, the effective focal length of the front lens group is f u1 , the effective focal length of the rear lens is f u2 , the maximum image height of industrial lens is IH, f u1 、f u2 The following relationship is satisfied between IH: 17.6≤(f u1 +f u2 ) / IH≤19.1.

[0012] As a specific implementation, the maximum field of view of the industrial lens is FOV, the head aperture size of the industrial lens is D, and the total optical length of the industrial lens is TTL, satisfying the following relationship: FOV / (D×TTL)≥0.006.

[0013] As a specific implementation, the maximum image plane height of the industrial lens is IH, and the aperture value of the industrial lens is FNO, and the two satisfy the following relationship: IH / FNO≥2.4.

[0014] As a specific implementation, the refractive index of the eighth lens L8 is N d8 , the Abbe number is V D8 , N d8 and V D8 Satisfy: N d8 ≤1.8;V D8 ≥27.5.

[0015] As a specific implementation, when the fourth lens L4 adopts a biconvex positive lens, the fifth lens L5 adopts a biconcave negative lens, and the eighth lens L8 adopts a biconvex positive lens, the air distance from the first lens L1 to the second lens L2 is 0.7200 mm; the air distance from the second lens L2 to the third lens L3 is 4.4179 mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1000 mm; the air distance from the fifth lens L5 to the aperture C is 9.2135 mm; the air distance from the aperture C to the sixth lens is 5.2978 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 0.1904 mm; and the air distance from the eighth lens L8 to the image plane IMG is 25.6333 mm.

[0016] As a specific implementation manner, when the fourth lens L4 adopts a positive meniscus lens with a convex surface facing the object, the fifth lens L5 adopts a negative meniscus lens with a convex surface facing the object, and the eighth lens L8 adopts a double convex positive lens, the air distance from the first lens L1 to the second lens L2 is 0.1890 mm; the air distance from the second lens L2 to the third lens L3 is 3.3234 mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1197 mm; the air distance from the fifth lens L5 to the aperture C is 10.2199 mm; the air distance from the aperture C to the sixth lens is 3.2825 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 3.2919 mm; and the air distance from the eighth lens L8 to the image plane IMG is 24.3376 mm.

[0017] As a specific implementation manner, when the fourth lens L4 adopts a double convex positive lens, the fifth lens L5 adopts a double concave negative lens, and the eighth lens L8 adopts a meniscus positive lens with the convex surface facing the image side, the air distance from the first lens L1 to the second lens L2 is 0.1873 mm; the air distance from the second lens L2 to the third lens L3 is 6.2133 mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1232 mm; the air distance from the fifth lens L5 to the aperture C is 8.0854 mm; the air distance from the aperture C to the sixth lens is 4.3740 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 2.8323 mm; and the air distance from the eighth lens L8 to the image plane IMG is 24.3643 mm.

[0018] Compared with the prior art, the present invention provides a miniaturized industrial lens with a large target surface, low distortion and high resolution, which has the following beneficial effects:

[0019] 1) The present invention cements the fourth lens L4 and the fifth lens L5, and the sixth lens L6 and the seventh lens L7, and requires that the focal length of the two cemented lenses, the total focal length of the industrial lens, and the maximum field angle of the optical lens satisfy 0.5≤|(f G1×f / f G2 )×tan(FOV / 4)|≤1.5, which can effectively improve the distortion of the optical system, reduce the assembly sensitivity of the system, and meet the demand for low distortion;

[0020] 2) The present invention controls the focal length of the front lens group and the rear lens group so that the maximum image plane height of the industrial lens satisfies 17.6≤(f u1 +f u2 ) / IH≤19.1, to meet the needs of large-surface imaging; and by reasonably allocating the proportion of the focal length of the front lens group, the rear lens group and the focal length of the entire lens, that is, |f u1 / f|≤1.6,|f u2 / f|≥0.7, to meet the demand for high resolution;

[0021] 3) The present invention realizes miniaturization of the optical lens by limiting the relationship between the maximum field of view angle of the optical lens and the aperture size of the optical lens head and the total optical length of the optical lens, that is, FOV / (D×TTL)≥0.006;

[0022] 4) The present invention uses glass that is friendly to thermal drift, such as requiring the eighth lens L8 to meet N d8 ≤1.8;V D8 ≥27.5, to effectively improve the stability of the lens group. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the optical path diagram of the small-sized industrial lens with large target surface, low distortion and high resolution in Example 1;

[0024] Figure 2 The MTF curve of the small industrial lens with large target surface, low distortion and high resolution in the visible light band in Example 1;

[0025] Figure 3 The field curvature and distortion diagram of the small industrial lens with large target surface, low distortion and high resolution in the visible light band in Example 1;

[0026] Figure 4 This is the optical path diagram of the small-sized industrial lens with large target surface, low distortion and high resolution in Example 2;

[0027] Figure 5 The MTF curve of the small industrial lens with large target surface, low distortion and high resolution in the visible light band in Example 2;

[0028] Figure 6 The field curvature and distortion diagram of the small industrial lens with large target surface, low distortion and high resolution in the visible light band in Example 2;

[0029] Figure 7This is the optical path diagram of the small-sized industrial lens with large target surface, low distortion and high resolution in Example 3;

[0030] Figure 8 The MTF curve of the small industrial lens with large target surface, low distortion and high resolution in the visible light band in Example 3;

[0031] Fig. 9 The field curvature and distortion diagram of the small industrial lens with large target surface, low distortion and high resolution in the visible light band in Example 3. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention provides a small-sized industrial lens with a large target surface, low distortion and high resolution, which comprises, in order from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture C, a sixth lens L6, a seventh lens L7 and an eighth lens L8.

[0034] Among them, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 constitute a front lens group, the sixth lens L6, the seventh lens L7 and the eighth lens L8 constitute a rear lens group, among which the first lens L1, the third lens L3, the fourth lens L4, the seventh lens L7 and the eighth lens L8 have positive refractive power, and the second lens L2, the fifth lens L5 and the sixth lens L6 have negative refractive power.

[0035] Specifically, in the optical system, the first lens L1 is a biconvex positive lens; the second lens L2 is a biconcave negative lens; the third lens L3 is a positive meniscus lens with the convex surface facing the object; the fourth lens L4 is a biconvex positive lens or a positive meniscus lens with the convex surface facing the object; the fifth lens L5 is a biconcave negative lens or a negative meniscus lens with the convex surface facing the object; the sixth lens L6 is a negative meniscus lens with the convex surface facing the image; the seventh lens L7 is a positive meniscus lens with the convex surface facing the image; the eighth lens L8 is a biconvex positive lens or a positive meniscus lens with the convex surface facing the image; the fourth lens L4 and the fifth lens L5 are in close contact to form a first cemented group; the sixth lens L6 and the seventh lens L7 are in close contact to form a second cemented group.

[0036] Here, the first lens L1 is required to have a larger aperture and curvature, which is beneficial for the lens to obtain light at a large angle; the second lens L2 can calibrate the light collected by the first lens L1, which is beneficial for improving the imaging quality of the rear optical system; the third lens L3 can focus the light collected by the second lens L2, so that the light is more evenly incident on the rear optical system; the fourth lens L4 and the fifth lens L5 are glued together to reduce the distortion produced by the lens. Both of them use glass lenses, which can effectively improve the imaging stability of the lens group in the working environment.

[0037] The aperture C is placed between the fifth lens L5 and the sixth lens L6 to control the imaging quality and the performance of the optical system by limiting the propagation range and direction of the light beam. The sixth lens L6 and the seventh lens L7 are glued together to eliminate or balance the distortion produced by the lens and reduce the tolerance sensitivity. Here, the sixth lens L6 and the seventh lens L7 are also made of glass lenses, which can effectively improve the stability and durability of the lens group.

[0038] The eighth lens L8 can focus the light collected by the seventh lens L7, which is beneficial to the field curvature correction of the lens and optimizes the imaging performance of the lens group.

[0039] Except for the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7, the materials of the remaining lenses in the optical system can be glass materials or plastic materials with conventional refractive index. Example 1

[0040] In the optical system of this example, the fourth lens L4 is a double convex positive lens, the fifth lens L5 is a double concave negative lens, and the eighth lens L8 is a double convex positive lens. Figure 1 shown.

[0041] See Table 1, which lists the relevant parameters of each lens in this example, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0042] Table 1

[0043]

[0044] Infinity means infinity.

[0045] In this example, the air distance from the first lens L1 to the second lens L2 is 0.7200 mm; the air distance from the second lens L2 to the third lens L3 is 4.4179 mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1000 mm; the air distance from the fifth lens L5 to the aperture C is 9.2135 mm; the air distance from the aperture C to the sixth lens is 5.2978 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 0.1904 mm; and the air distance from the eighth lens L8 to the image plane IMG is 25.6333 mm.

[0046] The technical indicators achieved by the optical system in this example are as follows:

[0047] 1) Maximum field of view of industrial lens: FOV = 11.1800°;

[0048] 2) Effective focal length of the first cemented group: f G1 =-25.6691 mm;

[0049] 3) Effective focal length of the second cemented group: f G2 =316.9816 mm;

[0050] 4) Effective focal length of the front lens: f u1 =76.7593 mm;

[0051] 5) Effective focal length of the rear lens group: f u2 =33.7615 mm;

[0052] 7) Total focal length of the optical system: f = 48.1242 mm;

[0053] 7) The head aperture size of the industrial lens: D = 24.0000 mm;

[0054] 8) Total optical length of industrial lens: TTL = 69.0229 mm;

[0055] 9) Maximum image height of industrial lens: IH = 5.8108 mm;

[0056] 10) Aperture value of optical lens: FNO = 2.3813;

[0057] 11) Refractive index of the eighth lens L8: N d8 =1.76;

[0058] 12) Abbe number of the eighth lens L8: V D8 =27.55.

[0059] Then we get:|(f G1 ×f / f G2)×tan(FOV / 4)|=1.4075;(f u1 +f u2 ) / IH=19.0199;|f u1 / f|=1.5950;|f u2 / f|=0.7015; FOV / (D×TTL)=0.0067; IH / FNO=2.4402.

[0060] Here, the fourth lens L4 and the fifth lens L5, the sixth lens L6 and the seventh lens L7 are cemented lenses. The cementation of the lenses can effectively improve the distortion of the optical system and reduce the assembly sensitivity of the system.

[0061] The optical power of the fifth lens L5 is reasonably controlled to make TTL ≤ 69.1 mm to meet the miniaturization requirements.

[0062] The focus range of incident light is controlled by the aperture, so as to achieve the large target surface requirement of the lens. And by reasonably allocating the optical power of the front group and the rear group, it can achieve the requirements of large target surface and clear imaging.

[0063] The final imaging effect of the lens in this example is achieved through Figure 2 The MTF graph of the lens shows that the MTF curves in each field of view all drop gently and have good consistency. As can be seen from the graph, the MTF value of the edge field of view at the spatial frequency of 83pl / mm is greater than 0.60, which means that the lens has good imaging effect and resolution in the full field of view. Figure 3 From the field curvature distortion diagram, we can see that the distortion of this lens does not exceed 0.1%. Example 2

[0064] In this example, the fourth lens L4 is a positive meniscus lens with its convex surface facing the object, the fifth lens L5 is a negative meniscus lens with its convex surface facing the object, and the eighth lens L8 is a double convex positive lens. Figure 4 shown.

[0065] See Table 2, which lists the relevant parameters of each lens in this example, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0066] Table 2

[0067]

[0068] In this example, the air distance from the first lens L1 to the second lens L2 is 0.1890 mm; the air distance from the second lens L2 to the third lens L3 is 3.3234 mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1197 mm; the air distance from the fifth lens L5 to the aperture C is 10.2199 mm; the air distance from the aperture C to the sixth lens is 3.2825 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 3.2919 mm; and the air distance from the eighth lens L8 to the image plane IMG is 24.3376 mm.

[0069] The technical indicators achieved by the optical system in this example are as follows:

[0070] 1) Maximum field of view of industrial lens: FOV = 11.1800°;

[0071] 2) Effective focal length of the first cemented group: f G1 =-29.0135 mm;

[0072] 3) Effective focal length of the second cemented group: f G2 =843.0969 mm;

[0073] 4) Effective focal length of the front lens: f u1 =69.4252 mm;

[0074] 5) Effective focal length of the rear lens group: f u2 =36.6769 mm;

[0075] 7) Total focal length of the optical system: f = 48.1302 mm;

[0076] 7) The head aperture size of the industrial lens: D = 24.0000 mm;

[0077] 8) Total optical length of industrial lens: TTL = 69.0432 mm;

[0078] 9) Maximum image height of industrial lens: IH = 5.8108 mm;

[0079] 10) Aperture value of optical lens: FNO = 2.3907;

[0080] 11) Refractive index of the eighth lens L8: N d8 =1.76;

[0081] 12) Abbe number of the eighth lens L8: V D8 =27.55.

[0082] Then we get:|(f G1 ×f / f G2)×tan(FOV / 4)|=0.5892;(f u1 +f u2 ) / IH=18.2595;|f u1 / f|=1.4424;|f u2 / f|=0.7620;FOV / (D×TTL)=0.0067;IH / FNO=2.4306.

[0083] The final imaging effect of the lens in this example is achieved through Figure 5 , 6 To evaluate, from Figure 5 It can be seen that the MTF curves under each field of view are all declining smoothly and have good consistency. It can be seen from the figure that the MTF value is greater than 0.65 at the spatial frequency of 83pl / mm in the edge field of view, which means that the lens has good imaging effect and resolution in the full field of view. Figure 6 From the field curvature distortion diagram, we can see that the distortion of this lens does not exceed 0.06%. Example 3

[0084] In this example, the fourth lens L4 is a double convex positive lens, the fifth lens L5 is a double concave negative lens, and the eighth lens L8 is a meniscus positive lens with the convex surface facing the image side. Figure 7 shown.

[0085] See Table 3, which lists the relevant parameters of each lens in this example, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0086] Table 3

[0087]

[0088] In this example, the air distance from the first lens L1 to the second lens L2 is 0.1873 mm; the air distance from the second lens L2 to the third lens L3 is 6.2133 mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1232 mm; the air distance from the fifth lens L5 to the aperture C is 8.0854 mm; the air distance from the aperture C to the sixth lens is 4.3740 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 2.8323 mm; and the air distance from the eighth lens L8 to the image plane IMG is 24.3643 mm.

[0089] The technical indicators achieved by the optical system in this example are as follows:

[0090] 1) Maximum field of view of industrial lens: FOV = 11.1800°;

[0091] 2) Effective focal length of the first cemented group: f G1=-27.9464 mm;

[0092] 3) Effective focal length of the second cemented group: f G2 =-665.5831 mm;

[0093] 4) Effective focal length of the front lens: f u1 =64.1782 mm;

[0094] 5) Effective focal length of the rear lens group: f u2 =38.6292 mm;

[0095] 7) Total focal length of the optical system: f = 48.1392 mm;

[0096] 7) The head aperture size of the industrial lens: D = 24.0000 mm;

[0097] 8) Total optical length of industrial lens: TTL = 69.0324 mm;

[0098] 9) Maximum image height of industrial lens: IH = 5.8108 mm;

[0099] 10) Aperture value of optical lens: FNO = 2.3864;

[0100] 11) Refractive index of the eighth lens L8: N d8 =1.76;

[0101] 12) Abbe number of the eighth lens L8: V D8 =27.55.

[0102] Then we get:|(f G1 ×f / f G2 )×tan(FOV / 4)|=0.7300;(f u1 +f u2 ) / IH=17.6925;|f u1 / f|=1.3332;|f u2 / f|=0.8024;FOV / (D×TTL)=0.0067;IH / FNO=2.4350.

[0103] The final imaging effect of the lens in this example is achieved through Figure 8 , 9 To evaluate, from Figure 8 It can be seen that the MTF value of the edge field of view is greater than 0.60 at the spatial frequency of 83pl / mm; Fig. 9 It can be seen from the field curvature distortion diagram that the distortion does not exceed 0.45%.

[0104] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A small-sized industrial lens with large target surface, low distortion and high resolution, characterized in that: The industrial lens has 8 lenses in total, which include, in order from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture C, a sixth lens L6, a seventh lens L7 and an eighth lens L8, wherein the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 constitute a front lens group, and the sixth lens L6, the seventh lens L7 and the eighth lens L8 constitute a rear lens group, wherein the first lens L1, the third lens L3, the fourth lens L4, the seventh lens L7 and the eighth lens L8 have positive focal lengths, and the second lens L2, the fifth lens L5 and the sixth lens L6 have negative focal lengths; The first lens L1 is a biconvex positive lens; the second lens L2 is a biconcave negative lens; the third lens L3 is a positive meniscus lens with the convex surface facing the object; the fourth lens L4 is a biconvex positive lens or a positive meniscus lens with the convex surface facing the object; the fifth lens L5 is a biconcave negative lens or a negative meniscus lens with the convex surface facing the object; the sixth lens L6 is a negative meniscus lens with the convex surface facing the image; the seventh lens L7 is a positive meniscus lens with the convex surface facing the image; the eighth lens L8 is a biconvex positive lens or a positive meniscus lens with the convex surface facing the image; The fourth lens L4 and the fifth lens L5 are closely connected to form a first cemented group; the sixth lens L6 and the seventh lens L7 are closely connected to form a second cemented group; The total focal length of the industrial lens is f, and the effective focal length of the front lens is f u1 , the effective focal length of the rear lens is f u2 , f u1 、f u2 The following relationship is satisfied between |f u1 / f|≤1.6,0.7≤|f u2 / f|≤0.8024; In industrial lenses, the effective focal length of the front lens is f u1 , the effective focal length of the rear lens is f u2 , the maximum image height of industrial lens is IH, f u1 、f u2 The following relationship is satisfied between IH: 17.6≤(f u1 +f u2 ) / IH≤19.

1.

2. The miniaturized industrial lens with large target surface, low distortion and high resolution according to claim 1, characterized in that: The maximum field of view of the industrial lens is FOV, the head aperture size of the industrial lens is D, and the total optical length of the industrial lens is TTL, satisfying the following relationship: 0.006≤FOV / (D×TTL) ≤0.0067.

3. The miniaturized industrial lens with large target surface, low distortion and high resolution according to claim 1, characterized in that: The maximum image height of an industrial lens is IH, and the aperture value of an industrial lens is FNO. The two satisfy the following relationship: 2.4≤IH / FNO≤2.4402.

4. The miniaturized industrial lens with large target surface, low distortion and high resolution according to claim 1, characterized in that: The refractive index of the eighth lens L8 is N d8 , the Abbe number is V D8 , N d8 and V D8 Satisfy: N d8 ≤1.8;V D8 ≥27.

5.

5. The miniaturized industrial lens with large target surface, low distortion and high resolution according to claim 1, characterized in that: When the fourth lens L4 is a biconvex positive lens, the fifth lens L5 is a biconcave negative lens, and the eighth lens L8 is a biconvex positive lens, the air distance from the first lens L1 to the second lens L2 is 0.7200 mm; the air distance from the second lens L2 to the third lens L3 is 4.4179 mm; The air distance from the third lens L3 to the fourth lens L4 is 0.1000 mm; the air distance from the fifth lens L5 to the aperture C is 9.2135 mm; the air distance from the aperture C to the sixth lens is 5.2978 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 0.1904 mm; and the air distance from the eighth lens L8 to the image plane IMG is 25.6333 mm.

6. The miniaturized industrial lens with large target surface, low distortion and high resolution according to claim 1, characterized in that: When the fourth lens L4 adopts a positive meniscus lens with a convex surface facing the object, the fifth lens L5 adopts a negative meniscus lens with a convex surface facing the object, and the eighth lens L8 adopts a double convex positive lens, the air distance from the first lens L1 to the second lens L2 is 0.1890 mm; the air distance from the second lens L2 to the third lens L3 is 3.3234 mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1197 mm; the air distance from the fifth lens L5 to the aperture C is 10.2199 mm; the air distance from the aperture C to the sixth lens is 3.2825 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 3.2919 mm; and the air distance from the eighth lens L8 to the image plane IMG is 24.3377 mm.

7. The miniaturized industrial lens with large target surface, low distortion and high resolution according to claim 1, characterized in that: When the fourth lens L4 adopts a double convex positive lens, the fifth lens L5 adopts a double concave negative lens, and the eighth lens L8 adopts a meniscus positive lens with the convex surface facing the image side, the air distance from the first lens L1 to the second lens L2 is 0.1873mm; the air distance from the second lens L2 to the third lens L3 is 6.2133mm; the air distance from the third lens L3 to the fourth lens L4 is 0.1232mm; the air distance from the fifth lens L5 to the aperture C is 8.0854mm; the air distance from the aperture C to the sixth lens is 4.3740mm; the air distance from the seventh lens L7 to the eighth lens L8 is 2.8323mm; and the air distance from the eighth lens L8 to the image plane IMG is 24.3643mm.

Images