A multi-object distance, low distortion lens and camera device for machine vision

Abstract

The present invention provides a multi-object distance, low distortion lens and camera device for machine vision, wherein the lens comprises an optical system, the optical system comprises a first lens group, an aperture stop and a second lens group, the first lens group comprises a first lens, a second lens and a third lens, the second lens group comprises a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged on the same optical axis from the object side to the image side; the first lens is a biconvex lens with positive focal power, the second lens is a biconvex lens with positive focal power, the third lens is a biconcave lens with negative focal power, the fourth lens is a biconvex lens with positive focal power, the fifth lens is a biconcave lens with negative focal power, the sixth lens is a meniscus lens with negative focal power, the seventh lens is a meniscus lens with positive focal power, and the eighth lens is a biconvex lens with positive focal power. The lens of the present invention has the advantages of a large object distance range, low distortion and high resolution.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial lenses, and in particular to a multi-object distance, low-distortion lens and a camera device for machine vision. Background Art

[0002] Machine vision lens is a key component in machine vision system. It is responsible for capturing and focusing light to form a digital image of the object inside the camera. It is widely used in intelligent monitoring and security systems, industrial automation and robot vision systems, traffic monitoring systems and intelligent traffic management, etc. Among them, multi-object distance, low distortion, high-resolution visible imaging lens has a wide imaging range, high image quality, better visual effects, wider applicability and excellent performance, thus providing more comprehensive and accurate visual support for tasks such as image processing, target recognition and scene understanding. Therefore, it provides irreplaceable advantages in multiple application fields and is the first choice for many professional applications.

[0003] However, industrial lenses currently have further requirements for distortion and object distance range, and there is an urgent need for lens designs with a larger object distance range and smaller distortion. Summary of the invention

[0004] In order to solve the above problems in the prior art, the present invention provides a multi-object distance, low distortion lens and camera device for machine vision, which has the advantages of a large object distance range, low distortion and high resolution.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a multi-object distance, low distortion lens for machine vision, comprising an optical system, wherein the optical system comprises a first lens group, an aperture stop, and a second lens group arranged on the same optical axis from the object side to the image side, wherein the first lens group comprises a first lens, a second lens, and a third lens arranged on the same optical axis from the object side to the image side, and the second lens group comprises a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged on the same optical axis from the object side to the image side;

[0007] The first lens is a biconvex lens with positive optical power, the second lens is a biconvex lens with positive optical power, the third lens is a biconcave lens with negative optical power, the fourth lens is a biconvex lens with positive optical power, the fifth lens is a biconcave lens with negative optical power, the sixth lens is a meniscus lens with negative optical power, the seventh lens is a meniscus lens with positive optical power, and the eighth lens is a biconvex lens with positive optical power.

[0008] The beneficial effects of the present invention are as follows: the focal length of the lens optical module of the present invention is 50mm, the resolution can reach 250lp / mm, and the full-field optical distortion is less than 0.14%; the working distance is wide, and the back focus focusing method is adopted, and the imaging requirements can be met from 200mm to ∞, and it has the advantages of a large object distance range, low distortion and high resolution.

[0009] Optionally, the focal length F1 of the first lens, the focal length F2 of the second lens, the focal length F3 of the third lens, the focal length F4 of the fourth lens, the focal length F5 of the fifth lens, the focal length F6 of the sixth lens, the focal length F7 of the seventh lens, the focal length F8 of the eighth lens and the total focal length F of the optical system satisfy the following focal length relationship:

[0010] F1 / F=0.700;

[0011] F2 / F=0.514;

[0012] F3 / F=-0.280;

[0013] F4 / F=0.243;

[0014] F5 / F=-0.197;

[0015] F6 / F=-0.309;

[0016] F7 / F=0.432;

[0017] F8 / F=0.595.

[0018] Optionally, the total optical length TTL of the lens and the maximum image height IH corresponding to the maximum field of view angle of the lens satisfy:

[0019] 5≤TTL / IH≤6.

[0020] Optionally, the back focal length BFL of the lens and the total focal length F of the optical system satisfy:

[0021] 0.2≤BFL / F≤0.4.

[0022] Optionally, the air gap between the first lens and the second lens is 0.1 mm, the air gap between the second lens and the third lens is 0 mm, the air gap between the third lens and the aperture stop is 3.0 mm, the air gap between the aperture stop and the fourth lens is 2 mm, the air gap between the fourth lens and the fifth lens is 0 mm, the air gap between the fifth lens and the sixth lens is 14 mm, the air gap between the sixth lens and the seventh lens is 0 mm, the air gap between the seventh lens and the eighth lens is 0.1 mm, and the air gap between the eighth lens and the imaging plane is 14.5 mm.

[0023] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are all spherical lenses made of glass.

[0024] Optionally, the effective focal length of the lens is 50 mm, and the object distance range is 200 mm-∞.

[0025] In a second aspect, the present invention provides a camera module, including a photosensitive component and the lens of the first aspect;

[0026] The lens is mounted on the photosensitive component so that the photosensitive component is suitable for receiving light passing through the optical system and outputting imaging data.

[0027] Among them, the technical effect corresponding to the camera module provided in the second aspect refers to the relevant description of the multi-object distance, low distortion lens for machine vision provided in the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the optical structure of a multi-object distance, low-distortion lens for machine vision according to an embodiment of the present invention;

[0029] Figure 2 A modulation transfer function curve diagram of a multi-object distance, low distortion lens for machine vision according to an embodiment of the present invention;

[0030] Figure 3 It is a distortion curve diagram of a multi-object distance, low-distortion lens for machine vision according to an embodiment of the present invention.

[0031] Description of reference numerals:

[0032] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Aperture stop; 10. Imaging surface. DETAILED DESCRIPTION

[0033] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0034] Embodiment 1

[0035] Please refer to Figure 1 A multi-object distance, low distortion lens for machine vision, comprising an optical system, the optical system comprising a first lens group, an aperture stop 9 and a second lens group arranged on the same optical axis from the object side to the image side, the first lens group comprising a first lens 1, a second lens 2 and a third lens 3 arranged on the same optical axis from the object side to the image side, and the second lens group comprising a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7 and an eighth lens 8 arranged on the same optical axis from the object side to the image side. Among them, the first lens 1 is a biconvex lens with positive focal power, the second lens 2 is a biconvex lens with positive focal power, the third lens 3 is a biconcave lens with negative focal power, the fourth lens 4 is a biconvex lens with positive focal power, the fifth lens 5 is a biconcave lens with negative focal power, the sixth lens 6 is a meniscus lens with negative focal power, the seventh lens 7 is a meniscus lens with positive focal power, and the eighth lens 8 is a biconvex lens with positive focal power.

[0036] In this embodiment, the focal length F1 of the first lens 1, the focal length F2 of the second lens 2, the focal length F3 of the third lens 3, the focal length F4 of the fourth lens 4, the focal length F5 of the fifth lens 5, the focal length F6 of the sixth lens 6, the focal length F7 of the seventh lens 7, the focal length F8 of the eighth lens 8 and the total focal length F of the optical system satisfy the following focal length relationship:

[0037] F1 / F=0.700;

[0038] F2 / F=0.514;

[0039] F3 / F=-0.280;

[0040] F4 / F=0.243;

[0041] F5 / F=-0.197;

[0042] F6 / F=-0.309;

[0043] F7 / F=0.432;

[0044] F8 / F=0.595.

[0045] In this embodiment, the air gap between the first lens 1 and the second lens 2 is 0.1 mm, the air gap between the second lens 2 and the third lens 3 is 0 mm, the air gap between the third lens 3 and the aperture stop 9 is 3.0 mm, the air gap between the aperture stop 9 and the fourth lens 4 is 2 mm, the air gap between the fourth lens 4 and the fifth lens 5 is 0 mm, the air gap between the fifth lens 5 and the sixth lens 6 is 14 mm, the air gap between the sixth lens 6 and the seventh lens 7 is 0 mm, the air gap between the seventh lens 7 and the eighth lens 8 is 0.1 mm, and the air gap between the eighth lens 8 and the imaging plane 10 is 14.5 mm.

[0046] In this embodiment, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7 and the eighth lens 8 are all spherical lenses made of glass, which are easy to process and detect.

[0047] In this embodiment, the total optical length TTL of the lens and the maximum image height IH corresponding to the maximum field angle of the lens satisfy: 5≤TTL / IH≤6. The back focal length BFL of the lens and the total focal length F of the optical system satisfy: 0.2≤BFL / F≤0.4.

[0048] In this embodiment, the effective focal length of the lens is 50 mm, the relative numerical aperture is F / 2.8, the full field angle is 12.5°, the diagonal size of the imaging surface 10 is 11 mm, the total optical length is 58.5 mm from the first lens 1 to the imaging surface 10, the working band is 400 nm-700 nm, the working distance is wide, and the back focus focusing method is adopted, and the imaging requirements can be met from 200 mm to ∞.

[0049] The optical parameters of each lens in this embodiment are shown in Table 1 below. The surface numbers in Table 1 are arranged in order from the object side to the image side. When the surface is a plane, the radius is infinite. Among them, the air gap between the second lens 2 and the third lens 3, the air gap between the fourth lens 4 and the fifth lens 5, and the air gap between the sixth lens 6 and the seventh lens 7 are all 0 mm, that is, the two lenses in the above three groups of lenses are attached, so there is only one surface here, so there are 14 surfaces in total.

[0050] Table 1

[0051]

[0052] like Figure 2As shown, the cut-off frequency of the multi-object distance, low-distortion lens for machine vision in this embodiment is 250lp / mm at the full field of view, the corresponding modulation transfer function value is better than 0.3, and the modulation transfer function curves of each field of view are relatively concentrated, indicating that the multi-object distance, low-distortion lens for machine vision in this embodiment can achieve high-precision detection of targets. Wherein, OTF is the optical transfer function.

[0053] like Figure 3 As shown, the distortion value of a multi-object distance, low-distortion lens for machine vision in this embodiment is less than 0.14% within the full field of view, achieving low distortion.

[0054] At the same time, the relative illumination value of the multi-object distance, low-distortion lens for machine vision in the present embodiment is greater than 90% in the whole field of view, thus avoiding the occurrence of dark corners.

[0055] Embodiment 2

[0056] This embodiment provides a camera module, including a photosensitive component and a multi-object distance, low distortion lens for machine vision in Embodiment 1. The lens is mounted on the photosensitive component, so that the photosensitive component is suitable for receiving light passing through the optical system and outputting imaging data.

[0057] In summary, it can be seen that the imaging lens of this embodiment has the characteristics of multiple object distances, high resolution, low distortion and high-precision detection.

[0058] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0059] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0061] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0062] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A multi-object distance, low distortion lens for machine vision, characterized in that: An optical system is included, wherein the optical system only includes a first lens group, an aperture stop, and a second lens group which are arranged on the same optical axis from the object side to the image side, wherein the first lens group only includes a first lens, a second lens, and a third lens which are arranged on the same optical axis from the object side to the image side, and the second lens group only includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens which are arranged on the same optical axis from the object side to the image side; The first lens is a biconvex lens with positive focal power, the second lens is a biconvex lens with positive focal power, the third lens is a biconcave lens with negative focal power, the fourth lens is a biconvex lens with positive focal power, the fifth lens is a biconcave lens with negative focal power, the sixth lens is a meniscus lens with negative focal power, the object side of which is concave and the image side is convex, the seventh lens is a meniscus lens with positive focal power, the object side of which is concave and the image side is convex, and the eighth lens is a biconvex lens with positive focal power; The focal length F1 of the first lens, the focal length F2 of the second lens, the focal length F3 of the third lens, the focal length F4 of the fourth lens, the focal length F5 of the fifth lens, the focal length F6 of the sixth lens, the focal length F7 of the seventh lens, the focal length F8 of the eighth lens and the total focal length F of the optical system satisfy the following focal length relationship: F1 / F=0.700; F2 / F=0.514; F3 / F=-0.280; F4 / F=0.243; F5 / F=-0.197; F6 / F=-0.309; F7 / F=0.432; F8 / F=0.

595.

2. The multi-object distance, low distortion lens for machine vision according to claim 1, characterized in that: The total optical length TTL of the lens and the maximum image height IH corresponding to the maximum field of view of the lens satisfy: 5≤TTL / IH≤6.

3. The multi-object distance, low distortion lens for machine vision according to claim 2, characterized in that: The back focal length BFL of the lens and the total focal length F of the optical system satisfy: 0.2≤BFL / F≤0.

4.

4. A multi-object distance, low distortion lens for machine vision according to any one of claims 1 to 3, characterized in that: The air gap between the first lens and the second lens is 0.1 mm, the air gap between the second lens and the third lens is 0 mm, the air gap between the third lens and the aperture stop is 3.0 mm, the air gap between the aperture stop and the fourth lens is 2 mm, the air gap between the fourth lens and the fifth lens is 0 mm, the air gap between the fifth lens and the sixth lens is 14 mm, the air gap between the sixth lens and the seventh lens is 0 mm, the air gap between the seventh lens and the eighth lens is 0.1 mm, and the air gap between the eighth lens and the imaging plane is 14.5 mm.

5. A multi-object distance, low distortion lens for machine vision according to any one of claims 1 to 3, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are all spherical lenses made of glass.

6. A multi-object distance, low distortion lens for machine vision according to any one of claims 1 to 3, characterized in that: The effective focal length of the lens is 50 mm, and the object distance range is 200 mm-∞.

7. A camera module, characterized in that: Comprising a photosensitive component and the lens according to any one of claims 1 to 6; The lens is mounted on the photosensitive component so that the photosensitive component is suitable for receiving light passing through the optical system and outputting imaging data.

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