CN113281882A

CN113281882A - Optical lens and image acquisition component

Info

Publication number: CN113281882A
Application number: CN202110551943.3A
Authority: CN
Inventors: 吴筱; 李鹏飞; 丁有爽; 邵天兰
Original assignee: Mech Mind Robotics Technologies Co Ltd
Current assignee: Mech Mind Robotics Technologies Co Ltd
Priority date: 2021-05-20
Filing date: 2021-05-20
Publication date: 2021-08-20
Anticipated expiration: 2041-05-20
Also published as: CN113281882B

Abstract

The application provides an optical lens and an image acquisition component, wherein the optical lens comprises a reverse telephoto lens group and a rear lens group which are coaxially arranged from an object side to an image side in sequence; the anti-telephoto lens group comprises a first negative lens group and a second positive lens group which are arranged in sequence; the first negative lens group comprises at least one lens, and the second positive lens group comprises at least one lens; the rear lens group includes at least one lens. The application provides an optical lens, through setting up anti-telephoto lens group and rear lens group, anti-telephoto lens group is used for converging the light of penetrating into to in the light incidence to rear lens group after the convergence, can realize low distortion under the condition of camera lens realization wide field angle, thereby guarantee to be shot image quality and the resolution ratio of target.

Description

Optical lens and image acquisition component

Technical Field

The application belongs to the technical field of optical devices, and particularly relates to an optical lens and an image acquisition component.

Background

With the development of computer vision technology, an image acquisition component and a robot can be combined, and the image acquisition component serves as the eyes of the robot and can assist the robot to complete work in a specific industry. Taking industries such as manufacturing and logistics as examples, the image acquisition component and the robot can be combined to complete work such as stacking, feeding, object grabbing and the like.

The image acquisition component may generally include devices such as an optical lens, an image sensor, and an image processor, and the design of the optical lens will directly affect the imaging quality, and the imaging quality will affect the working accuracy of the robot. In some application scenarios, such as an article grabbing application scenario, in a case where the article is large in size, the optical lens is required to have a large field angle to complete image acquisition.

In general, the angle of field of an optical lens can be increased by decreasing the focal length of the optical lens, but decreasing the focal length of the lens tends to increase the lens distortion, resulting in a decrease in image quality.

Disclosure of Invention

To overcome, at least to some extent, the problems in the related art, the present application provides an optical lens and an image pickup device.

According to a first aspect of embodiments of the present application, there is provided an optical lens including a reverse telephoto lens group and a rear lens group coaxially arranged in order from an object side to an image side; the focal length of the lens is [4.6mm, 6mm ], the field angle of the lens is 80-90 degrees, and the f-number is 1.7-2.5;

the anti-telephoto lens group comprises a first negative lens group and a second positive lens group which are arranged in sequence; the first negative lens group comprises at least one lens, and the second positive lens group comprises at least one lens; the rear lens group includes at least one lens.

In the above optical lens barrel, a diaphragm is further included, and the diaphragm is disposed between the reverse telephoto lens group and the rear lens group.

Further, the aperture of the diaphragm is: 5 mm-9 mm.

In the optical lens, the distance between the reverse telephoto lens group and the rear lens group is 2mm to 13 mm; the distance between the first negative lens group and the second positive lens group is 0.8 mm-3 mm.

In the optical lens, the focal length of the first negative lens group is-27 mm to-15 mm; the focal length of the second positive lens group is 6-17 mm; the focal length of the rear lens group is 6 mm-17 mm.

Further, the first negative lens group comprises a first negative lens and a second positive lens which are arranged in sequence, and the focal length of the first negative lens is-12 mm to-8 mm; the focal length of the second positive lens is 50-57 mm; the distance between the first negative lens and the second positive lens is 2 mm-6 mm.

Furthermore, the second positive lens group comprises a third negative lens and a fourth positive lens which are arranged in sequence, and the focal length of the third negative lens is-30 mm to-34 mm; the focal length of the fourth positive lens is 10-14 mm; the distance between the third negative lens and the fourth positive lens ranges from 3mm to 6 mm.

Furthermore, the rear lens group comprises a fifth positive lens and a sixth positive lens which are arranged in sequence, and the focal length of the fifth positive lens is 31-35 mm; the focal length of the sixth positive lens is 18-22 mm; and the distance between the fifth positive lens and the sixth positive lens is 2-7 mm.

Furthermore, the first negative lens and the second positive lens are spherical lenses made of optical glass, and the third negative lens, the fourth positive lens, the fifth positive lens and the sixth positive lens are aspheric lenses made of optical plastic.

According to a second aspect of embodiments of the present application, there is provided an image pickup element including the optical lens of any one of the above.

According to the above embodiments of the present application, at least the following advantages are obtained: the application provides an optical lens, through setting up anti-telephoto lens group and rear lens group, anti-telephoto lens group is used for converging the light of incidenting to in the light incidence of convergent back mirror group, through the focus [4.6mm, 6mm) that sets up the camera lens, make the angle of view of camera lens can satisfy at 80 ~ 90 within ranges, can reduce the camera lens distortion like this under the condition that the camera lens realized big angle of view, thereby under the condition that satisfies the angle of view demand, improve image quality, for example, improve the resolution ratio of image.

Furthermore, the focal length and material of each lens in the anti-telephoto lens group and the rear lens group and the distance between each adjacent lens are reasonably set, so that the lens can realize a large field angle, has low distortion, and meets the requirements of a machine vision system in robots in industries such as manufacturing and logistics.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the scope of the invention, as claimed.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification of the application, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

Fig. 1 is a schematic structural diagram of an optical lens provided in an embodiment of the present application.

Fig. 2 is a second schematic structural diagram of an optical lens according to an embodiment of the present disclosure.

Fig. 3 is a graph of an optical modulation transfer function of an optical system of the optical lens provided in the embodiment of the present application under normal temperature and pressure conditions.

Fig. 4 is a distortion curve diagram of an optical lens provided in an embodiment of the present application.

Fig. 5 is an image plane relative illuminance diagram of an optical lens provided in an embodiment of the present application.

Description of reference numerals:

1. a reverse telephoto lens group; 11. a first negative lens group; 111. a first negative lens; 112. a second positive lens; 12. a second positive lens group; 121. a third negative lens; 122. a fourth positive lens;

2. a rear lens group; 21. a fifth positive lens; 22. a sixth positive lens;

3. and (4) a diaphragm.

Detailed Description

For the purpose of promoting a clear understanding of the objects, aspects and advantages of the embodiments of the present application, reference will now be made to the accompanying drawings and detailed description, wherein like reference numerals refer to like elements throughout.

The illustrative embodiments and descriptions of the present application are provided to explain the present application and not to limit the present application. Additionally, the same or similar numbered elements/components used in the drawings and the embodiments are used to represent the same or similar parts.

As used herein, "first," "second," …, etc., are not specifically intended to mean in a sequential or chronological order, nor are they intended to limit the application, but merely to distinguish between elements or operations described in the same technical language.

With respect to directional terminology used herein, for example: up, down, left, right, front or rear, etc., are simply directions with reference to the drawings. Accordingly, the directional terminology used is intended to be illustrative and is not intended to be limiting of the present teachings.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

As used herein, "and/or" includes any and all combinations of the described items.

References to "plurality" herein include "two" and "more than two"; reference to "multiple sets" herein includes "two sets" and "more than two sets".

As used herein, the terms "substantially", "about" and the like are used to modify any slight variation in quantity or error that does not alter the nature of the variation. In general, the range of slight variations or errors that such terms modify may be 20% in some embodiments, 10% in some embodiments, 5% in some embodiments, or other values. It should be understood by those skilled in the art that the aforementioned values can be adjusted according to actual needs, and are not limited thereto.

Certain words used to describe the present application are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the present application.

In the industrial robot field, for example when needing industrial robot to accomplish work such as breaking a jam, pile up neatly, unordered work piece material loading, article snatch, have certain demand to the scope of the angle of view of machine vision camera lens, need great angle of view and image quality simultaneously. Generally, when the imaging size is the same, the larger the angle of view of the lens, the smaller the corresponding focal length, and the smaller the focal length, the larger the optical lens distortion, which affects the imaging quality.

The application provides an optical lens, through setting up anti-telephoto lens group and rear lens group, anti-telephoto lens group is used for converging the light of incidenting to in the light incidence of convergent back mirror group, through the focus [4.6mm, 6mm) that sets up the camera lens, make the angle of view of camera lens can satisfy at 80 ~ 90 within ranges, can reduce the camera lens distortion like this under the condition that the camera lens realized big angle of view, thereby under the condition that satisfies the angle of view demand, improve image quality, for example, improve the resolution ratio of image.

As shown in fig. 1, an optical lens provided in this embodiment of the present application includes a reverse telephoto lens group 1 and a rear lens group 2 coaxially arranged in order from an object side to an image side. Wherein, the distance between the reverse telephoto lens group 1 and the rear lens group 2 is 2mm to 13 mm. The focal length of the whole optical lens is 4.6mm, 6 mm. The field angle of the whole optical lens is 80-90 degrees, and the f-number is 1.7-2.5.

Wherein the reverse telephoto lens group 1 includes a first negative lens group 11 and a second positive lens group 12 which are arranged in this order. Specifically, the focal length of the first negative lens group 11 is-27 mm to-15 mm. The first negative lens group 11 includes at least one lens, and the lens may be made of optical glass material. The focal length of the second positive lens group 12 is 6mm to 17 mm. The second positive lens group 12 includes at least one lens, and the lens may be made of optical glass or optical plastic material.

The focal length of the rear lens group 2 is 6mm to 17 mm. The rear lens group 2 is a positive lens group, which includes at least one lens, and the lens can be made of optical glass or optical plastic material.

It should be noted that the lenses in the reverse telephoto lens group 1 and the rear lens group 2 may be spherical lenses or aspherical lenses.

In the optical lens provided by the embodiment of the application, the anti-telephoto lens group 1 and the rear lens group 2 converge incident light, and low distortion can be realized under the condition that the lens realizes a large field angle, so that the image quality and the resolution of a shot target are ensured. Through rationally setting the focal length, the material of each lens and the distance between each adjacent lens in anti-telephoto lens group 1 and the rear lens group 2, the camera lens can meet the requirements of a machine vision system in industrial robots such as manufacturing and logistics.

Since distortion is aberration that increases with the third power of the field height, the distortion of a large field lens is generally large. In the optical lens provided by the embodiment of the application, the surface type parameters, the structural parameters and the material of each lens in the lens and the distance between the lenses are reasonably set, so that the lens distortion can be effectively reduced, and the image quality is improved.

In a specific embodiment, the focal length of the entire optical lens is 5mm to 5.99mm, and the distance between the reverse telephoto lens group 1 and the rear lens group 2 is 2mm to 5 mm.

Note that the distance between the reverse telephoto lens group 1 and the rear lens group 2 refers to a straight-line distance between an intersection point of a surface of a lens close to the rear lens group 2 in the reverse telephoto lens group 1 and the optical lens main axis and an intersection point of a surface of a lens close to the reverse telephoto lens group 1 in the rear lens group 2 and the optical lens main axis.

In a specific embodiment, the distance between the first negative lens group 11 and the second positive lens group 12 in the reverse telephoto lens group 1 is 0.8mm to 3 mm.

Note that, as shown in fig. 2, the distance between the first negative lens group 11 and the second positive lens group 12 refers to a straight-line distance between an intersection point of a surface of a lens in the first negative lens group 11 close to the second positive lens group 12 and the principal axis of the optical lens and an intersection point of a surface of a lens in the second positive lens group 12 close to the first negative lens group 11 and the principal axis of the optical lens.

In a specific embodiment, the first negative lens group 11 comprises a first negative lens 111 and a second positive lens 112 arranged in sequence, wherein the focal length of the first negative lens 111 is-12 mm to-8 mm, and is made of lanthanum crown glass. The focal length of the second positive lens 112 is 50mm to 57mm, and the second positive lens is made of heavy flint glass or heavy barium flint glass.

The distance between the first negative lens 111 and the second positive lens 112 is 2mm to 6 mm.

As shown in fig. 2, assuming that an intersection point of the major axis of the first negative lens 111 and the surface of the first negative lens 111 close to the second positive lens 112 is point a and an intersection point of the major axis of the second positive lens 112 and the surface of the second positive lens 112 close to the first negative lens 111 is point B, the distance between the first negative lens 111 and the second positive lens 112 is the distance of the line segment AB.

In a specific embodiment, the second positive lens group 12 includes a third negative lens 121 and a fourth positive lens 122 sequentially disposed, wherein the third negative lens 121 has a focal length of-30 mm to-34 mm, and is made of optical plastic. The fourth positive lens 122 has a focal length of 10mm to 14mm and is made of optical plastic.

The distance between the third negative lens 121 and the fourth positive lens 122 ranges from 3mm to 6 mm.

As shown in fig. 2, assuming that an intersection of the major axis of the third negative lens 121 and the surface of the third negative lens 121 close to the fourth positive lens 122 is point C and an intersection of the major axis of the fourth positive lens 122 and the surface of the fourth positive lens 122 close to the third negative lens 121 is point D, the distance between the third negative lens 121 and the fourth positive lens 122 is the distance of the line segment CD.

In a specific embodiment, the rear lens group 2 includes a fifth positive lens 21 and a sixth positive lens 22, which are sequentially disposed, wherein the focal length of the fifth positive lens 21 is 31mm to 35mm, and is made of optical plastic. The focal length of the sixth positive lens 22 is 18 mm-22 mm, and the sixth positive lens is made of optical plastics.

The distance between the fifth positive lens 21 and the sixth positive lens 22 is 2mm to 7 mm.

As shown in fig. 2, assuming that an intersection of the major axis of the fifth positive lens 21 and the surface of the fifth positive lens 21 close to the sixth positive lens 22 is point E and an intersection of the major axis of the sixth positive lens 22 and the surface of the sixth positive lens 22 close to the fifth positive lens 21 is point F, the distance between the fifth positive lens 21 and the sixth positive lens 22 is the distance of the line segment EF.

In a specific embodiment, the diameter of the first negative lens 111 may be set to 15 mm. The total length of the whole optical lens is 35 mm-40 mm.

As an optional implementation manner of the embodiment of the present application, the optical lens provided in the embodiment of the present application further includes a stop 3, and the stop 3 is disposed between the anti-telephoto lens group 1 and the rear lens group 2. The aperture of the diaphragm 3 is: 5 mm-9 mm. The arrangement of the diaphragm 3 can ensure that coma or astigmatism of the whole lens is minimum, and meanwhile, the whole size of the lens can be smaller.

As an alternative implementation manner of the embodiment of the present application, the first negative lens 111 and the second positive lens 112 may each adopt a spherical lens, and the third negative lens 121, the fourth positive lens 122, the fifth positive lens 21, and the sixth positive lens 22 may each adopt an aspherical lens. Since the curvature radius of the aspheric lens varies with the central axis, it can be used to improve the optical quality, and therefore, the number of optical elements in the optical lens provided by the embodiment of the present application can be reduced by adopting aspheric lenses for the third negative lens 121, the fourth positive lens 122, the fifth positive lens 21 and the sixth positive lens 22, and a good imaging quality can be achieved with a smaller number of lenses, and the less the number of lenses, the less the optical energy loss, and the design cost can be reduced.

Of course, according to actual needs, the first negative lens 111 may be a spherical lens, and the second positive lens 112, the third negative lens 121, the fourth positive lens 122, the fifth positive lens 21, and the sixth positive lens 22 may be aspheric lenses. Aspheric lenses may be used for the first negative lens 111, the second positive lens 112, the third negative lens 121, the fourth positive lens 122, the fifth positive lens 21, and the sixth positive lens 22.

Specifically, the first negative lens 111 and the second positive lens 112 are spherical lenses made of optical glass, and the third negative lens 121, the fourth positive lens 122, the fifth positive lens 21, and the sixth positive lens 22 are aspheric lenses made of optical plastic.

The first negative lens 111 and the second positive lens 112 are spherical lenses made of optical glass, so that the influence of the external environment temperature on the inside of the lens can be effectively reduced, and the imaging quality reduction caused by temperature deformation of each aspheric lens made of optical plastic is avoided; in addition, since the glass has a high thermal deformation temperature, when the temperature of the working environment is high, the spherical lenses made of optical glass are not easily deformed by heat for both the first negative lens 111 and the second positive lens 112.

The processing technology of the aspheric lens made of the optical plastic material is simple, and the cost is low; in addition, the density of the optical plastic material is smaller than that of the optical glass material, and the optical plastic material is favorable for reducing the weight of the lens. By providing the first negative lens 111 and the second positive lens 112 as spherical lenses made of optical glass and the third lens, the fourth lens, the fifth lens, and the sixth lens as aspherical lenses made of optical plastic, a good imaging effect can be achieved with as few lenses as possible.

As an optional implementation manner of the embodiment of the present application, the optical lens provided in the embodiment of the present application further includes a filter, and the filter is disposed behind the rear lens group 2 along the incident direction of the light ray. When the optical lens is used in different application scenes, the light-passing spectrum range of the optical filter can be adjusted according to requirements, so that the optical lens can better image in a working spectrum.

As an optional implementation manner of the embodiment of the present application, the optical lens provided in the embodiment of the present application further includes a glass sheet, and the glass sheet is disposed behind the optical filter along the incident direction of the light ray. The glass sheet is used to protect a sensor in a camera used in cooperation with a lens.

As an optional implementation manner of the embodiment of the application, by reasonably selecting each lens and reasonably setting relevant parameters of each lens, the field angle of the lens can reach 80 to 90 degrees, that is, compared with the existing lens, the optical lens provided by the embodiment of the application can realize large-field monitoring; meanwhile, on the premise of a large field angle, the distortion of the full field of view is less than 0.8 percent. Therefore, the optical lens provided by the embodiment of the application can realize large-field low-distortion imaging.

By arranging the lenses in the optical lens according to the above embodiment, schematic diagrams representing the imaging effect of the lens can be obtained as shown in fig. 3, 4 and 5.

As shown in fig. 3, the Modulation Transfer Function (MTF) is a relationship between Modulation degree and logarithm of lines per millimeter in an image, and is used to evaluate detail reduction capability of a scene. The modulation is the ratio of the difference between the maximum and minimum intensity and the sum of the maximum and minimum intensity. The MTF is the ratio of the modulation of the image to the modulation of the object and is a function of the spatial frequency, which is usually expressed in lp/mm. The modulation transfer function can be used to characterize the optical system, with a higher MTF indicating a better imaging quality of the system.

In FIG. 3, the abscissa represents spatial frequency in lp/mm; the ordinate indicates the degree of modulation. The requirements of the optical lens on the MTF provided by the embodiment of the application are as follows: the MTF of the central field is more than or equal to 35% @145lp/mm, and the MTF of the edge field is more than or equal to 10% @145 lp/mm. The uppermost curve in the MTF plot is the MTF curve for the central field, which can be seen to be > 35% MTF for the central field at 145 lp/mm. The lowest curve in the MTF plot is the MTF curve for the marginal field, which can be seen to be > 10% MTF for the marginal field at 145 lp/mm. Therefore, the imaging quality of the optical lens provided by the embodiment of the application can meet the design requirement.

Fig. 4 is a distortion curve diagram of an optical lens provided in an embodiment of the present application. In the figure, the abscissa represents relative distortion in%; the ordinate represents the field angle.

The design requirements of the optical lens provided by the embodiment of the application are as follows: the relative distortion over the full field of view is < 1%.

As shown in fig. 4, the relative distortion of the optical lens provided in the embodiment of the present application is less than 0.8%, which can meet the design requirement.

Fig. 5 is an image plane relative illuminance diagram of an optical lens provided in the embodiment of the present application. As shown in fig. 5, the abscissa represents the angle of the field of view; the ordinate represents the image plane relative illuminance.

The design requirements of the optical lens provided by the embodiment of the application are as follows: the relative illumination of the image plane in the whole view field range is more than or equal to 50 percent.

As can be seen from fig. 5, the image plane relative illuminance of the optical lens provided in the embodiment of the present application in the whole field range is greater than 50%, and can meet the design requirement.

Based on the optical lens provided by the embodiment of the application, the application also provides an image acquisition component which comprises any one of the optical lenses.

Illustratively, the image capturing component may include a monocular camera, a binocular camera, a 3D camera, a video camera, or the like, which is not particularly limited herein.

The foregoing is merely an illustrative embodiment of the present application, and any equivalent changes and modifications made by those skilled in the art without departing from the spirit and principles of the present application shall fall within the protection scope of the present application.

Claims

1. An optical lens is characterized by comprising a reverse telephoto lens group and a rear lens group which are coaxially arranged from an object side to an image side in sequence; the focal length of the lens is [4.6mm, 6mm ], the field angle of the lens is 80-90 degrees, and the f-number is 1.7-2.5;

2. An optical lens according to claim 1, further comprising a stop disposed between the reverse telephoto lens group and the rear lens group.

3. An optical lens according to claim 2, characterized in that the aperture of the diaphragm is: 5 mm-9 mm.

4. An optical lens barrel according to claim 1, 2 or 3, wherein a distance between the reverse telephoto lens group and the rear lens group is 2mm to 13 mm; the distance between the first negative lens group and the second positive lens group is 0.8 mm-3 mm.

5. An optical lens according to claim 1, 2, 3 or 4, characterized in that the focal length of the first negative lens group is-27 mm to-15 mm; the focal length of the second positive lens group is 6-17 mm; the focal length of the rear lens group is 6 mm-17 mm.

6. An optical lens according to claim 5, wherein the first negative lens group comprises a first negative lens and a second positive lens which are arranged in sequence, and the focal length of the first negative lens is-12 mm to-8 mm; the focal length of the second positive lens is 50-57 mm; the distance between the first negative lens and the second positive lens is 2 mm-6 mm.

7. An optical lens according to claim 6, wherein the second positive lens group comprises a third negative lens and a fourth positive lens which are arranged in sequence, and the focal length of the third negative lens is-30 mm to-34 mm; the focal length of the fourth positive lens is 10-14 mm; the distance between the third negative lens and the fourth positive lens ranges from 3mm to 6 mm.

8. An optical lens according to claim 7, wherein the rear lens group comprises a fifth positive lens and a sixth positive lens which are arranged in sequence, and the focal length of the fifth positive lens is 31mm to 35 mm; the focal length of the sixth positive lens is 18-22 mm; and the distance between the fifth positive lens and the sixth positive lens is 2-7 mm.

9. An optical lens barrel according to claim 8, wherein the first negative lens and the second positive lens each employ a spherical lens made of optical glass, and the third negative lens, the fourth positive lens, the fifth positive lens and the sixth positive lens each employ an aspherical lens made of optical plastic.

10. An image pickup element comprising the optical lens according to any one of claims 1 to 9.