CN113281882B

CN113281882B - Optical lens and image acquisition component

Info

Publication number: CN113281882B
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: 2023-06-27
Anticipated expiration: 2041-05-20
Also published as: CN113281882A

Abstract

The application provides an optical lens and an image acquisition component, wherein the optical lens comprises an anti-telephoto lens group and a rear lens group which are coaxially arranged in sequence from an object side to an image side; the anti-telephoto lens group comprises a first negative lens group and a second positive lens group which are sequentially arranged; 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 optical lens provided by the application is provided with the anti-telephoto lens group and the rear lens group, and the anti-telephoto lens group is used for converging incident light rays so that the converged light rays are incident into the rear lens group, and low distortion can be realized under the condition that the lens realizes a large field angle, so that the image quality and resolution of a shot target are ensured.

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, the image acquisition component and the robot can be combined, and the image acquisition component serves as eyes of the robot and can assist the robot to complete work in specific industries. Taking industries such as manufacturing and logistics as an example, the combination of the image acquisition component and the robot can finish the work such as stacking, feeding, grabbing articles and the like.

The image acquisition component may generally comprise an optical lens, an image sensor, an image processor and other devices, wherein the design of the optical lens directly influences the imaging quality, and the imaging quality influences the working accuracy of the robot. In some application scenarios, such as an article grabbing application scenario, in a case of a large article volume, the optical lens needs to have a large field angle to complete image acquisition.

In general, the angle of view 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 cause an increase in distortion of the lens, resulting in a decrease in image quality.

Disclosure of Invention

In order to overcome the problems in the related art to at least a certain extent, the present application provides an optical lens and an image capturing element.

According to a first aspect of embodiments of the present application, there is provided an optical lens including a 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 sequentially arranged; the first negative lens group includes at least one lens, and the second positive lens group includes at least one lens; the rear lens group includes at least one lens.

The optical lens further comprises a diaphragm, and the diaphragm is arranged between the anti-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 anti-telephoto lens group and the rear lens group is 2 mm-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 mm-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 sequentially arranged, 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.

Further, the second positive lens group comprises a third negative lens and a fourth positive lens which are sequentially arranged, 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 mm-14 mm; the distance between the third negative lens and the fourth positive lens ranges from 3mm to 6mm.

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

Further, 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 capturing component comprising an optical lens as described in any one of the above.

According to the above specific embodiments of the present application, at least the following advantages are achieved: the optical lens that this application provided, through setting up anti-telephoto lens group and back lens group, anti-telephoto lens group is arranged in converging the light of penetrating to in the light incidence back mirror group after the convergence, through setting up the focus [4.6mm,6mm ] of camera lens, make the angle of view of camera lens can satisfy in 80 ~ 90 within range, can reduce the camera lens distortion under the circumstances that the camera lens realized big angle of view like this, thereby under the circumstances that satisfies the angle of view demand, improve image quality, such as the resolution ratio of improvement image.

Further, through reasonably setting the focal length and the material of each lens in the anti-telephoto lens group and the rear lens group and the distance between each adjacent lens, the lens can realize a large field angle, has low distortion and meets the requirements of a machine vision system in robots in the industries of manufacturing, logistics and the like.

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 this specification, 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 according to 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 diagram of optical modulation transfer functions of an optical system under normal temperature and normal pressure conditions of the optical lens provided in the embodiment of the application.

Fig. 4 is a distortion graph 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 according to an embodiment of the present application.

Reference numerals illustrate:

1. a retroactive 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. a diaphragm.

Detailed Description

For the purposes of clarity, technical solutions and advantages of embodiments of the present application, the following drawings and detailed description will clearly illustrate the spirit of the disclosure of the present application, and any person skilled in the art, after having the knowledge of the embodiments of the present application, may make changes and modifications by the techniques taught by the present application, without departing from the spirit and scope of the present application.

The exemplary embodiments of the present application and their description are for the purpose of explaining the present application, but are not limiting of the present application. In addition, the same or similar reference numerals are used for the same or similar parts in the drawings and the embodiments.

The terms "first," "second," …, and the like, as used herein, do not denote a particular order or sequence, nor are they intended to limit the application to distinguishing between elements or operations that are described in the same technical language.

With respect to directional terms used herein, for example: upper, lower, left, right, front or rear, etc., are merely references to the directions of the drawings. Thus, directional terminology is used for purposes of illustration and is not intended to be limiting.

As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.

As used herein, "and/or" includes any or all combinations of such things.

Reference herein to "a plurality" includes "two" and "more than two"; the term "plurality of sets" as used herein includes "two sets" and "more than two sets".

The terms "about," "approximately" and the like as used herein are used to modify any quantity or error that could be slightly varied without the slight variation or error altering its nature. In general, the range of slight variations or errors modified by such terms 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 above mentioned values can be adjusted according to the actual requirements, and are not limited thereto.

Certain terms used to describe the application will be discussed below, or elsewhere in this specification, to provide additional guidance to those skilled in the art in connection with the description of the application.

In the field of industrial robots, for example, when the industrial robots are required to complete the work of unstacking, stacking, disordered workpiece loading, article grabbing and the like, the range of the field angle of the machine vision lens is required to be certain, and meanwhile, a larger field angle and imaging quality are required. Generally, when the imaging size is the same, the larger the field angle of the lens is, the smaller the corresponding focal length is, and the smaller the focal length is, the distortion of the optical lens is increased correspondingly, and the imaging quality is affected, so that there is a need for an optical lens capable of satisfying both the field angle and the imaging quality.

The optical lens that this application provided, through setting up anti-telephoto lens group and back lens group, anti-telephoto lens group is arranged in converging the light of penetrating to in the light incidence back mirror group after the convergence, through setting up the focus [4.6mm,6mm ] of camera lens, make the angle of view of camera lens can satisfy in 80 ~ 90 within range, can reduce the camera lens distortion under the circumstances that the camera lens realized big angle of view like this, thereby under the circumstances that satisfies the angle of view demand, improve image quality, such as the resolution ratio of improvement image.

As shown in fig. 1, the optical lens provided in the embodiment of the present application includes a back 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 anti-telephoto lens group 1 and the rear lens group 2 is 2mm to 13mm. The focal length of the whole optical lens is [4.6mm,6mm ]. The angle of view of the whole optical lens is 80-90 degrees, and the f-number is 1.7-2.5.

Wherein the anti-telephoto lens group 1 comprises a first negative lens group 11 and a second positive lens group 12 which are sequentially arranged. 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 an optical glass material. The focal length of the second positive lens group 12 is 6mm to 17mm. The second positive lens group 12 includes at least one lens, which may be made of optical glass or optical plastic material.

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

The lenses in the anti-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 both 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 resolution of a shot target are ensured. By reasonably setting the focal length and the material of each lens in the anti-telephoto lens group 1 and the rear lens group 2 and the distance between each adjacent lens, the lens can meet the requirements of a machine vision system in robots in industries such as manufacturing, logistics and the like.

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

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

The distance between the anti-telephoto lens group 1 and the rear lens group 2 refers to a linear distance between an intersection point of a surface of the lens of the anti-telephoto lens group 1 near the rear lens group 2 and the optical lens main axis and an intersection point of a surface of the lens of the rear lens group 2 near the anti-telephoto lens group 1 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 anti-telephoto lens group 1 is 0.8mm to 3mm.

As shown in fig. 2, the distance between the first negative lens group 11 and the second positive lens group 12 refers to a linear distance between an intersection point of the surface of the lens of the first negative lens group 11, which is close to the second positive lens group 12, and the optical lens main axis and an intersection point of the surface of the lens of the second positive lens group 12, which is close to the first negative lens group 11, and the optical lens main axis.

In a specific embodiment, the first negative lens group 11 includes a first negative lens 111 and a second positive lens 112 sequentially disposed, wherein the focal length of the first negative lens 111 is-12 mm to-8 mm, and is made of lanthanum crown glass. The second positive lens 112 has a focal length of 50mm to 57mm and 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 6mm.

As shown in fig. 2, assuming that the intersection point of the principal axis of the first negative lens 111 and the surface of the first negative lens 111 adjacent to the second positive lens 112 is a point a, and the intersection point of the principal axis of the second positive lens 112 and the surface of the second positive lens 112 adjacent to the first negative lens 111 is a point B, the distance between the first negative lens 111 and the second positive lens 112 refers to 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 focal length of the third negative lens 121 is-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 an optical plastic.

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

As shown in fig. 2, assuming that an intersection point of the principal axis of the third negative lens 121 and the surface of the third negative lens 121 near the fourth positive lens 122 is a point C and an intersection point of the principal axis of the fourth positive lens 122 and the surface of the fourth positive lens 122 near the third negative lens 121 is a point D, a distance between the third negative lens 121 and the fourth positive lens 122 refers to a 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 disposed in this order, wherein the focal length of the fifth positive lens 21 is 31mm to 35mm, which is made of an optical plastic. The focal length of the sixth positive lens 22 is 18mm to 22mm, which is made of optical plastic.

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

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

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

As an alternative implementation manner of the embodiment of the present application, the optical lens provided in the embodiment of the present application further includes a diaphragm 3, where the diaphragm 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 entire lens is minimized, and at the same time, the overall size of the lens can be made small.

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

Of course, as the first negative lens 111, 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 all be aspherical lenses, as required. Aspherical 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 aspherical 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 reduction of imaging quality caused by temperature deformation of each aspherical lens made of optical plastic is avoided; in addition, since the glass thermal deformation temperature is high, when the temperature of the working environment is high, the spherical lenses made of optical glass are not easily deformed by 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 beneficial to 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 providing the third lens, the fourth lens, the fifth lens, and the sixth lens as aspherical lenses made of optical plastic, a preferable 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 an optical filter, and the optical filter is disposed behind the rear lens group 2 along the light incident direction. When the optical lens is used for different application scenes, the spectral range of the light passing through the optical filter can be adjusted according to the requirements, so that the optical lens can be better imaged 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 light incident direction. The glass sheet is used to protect the sensors in the camera that are used in conjunction with the lens.

As an optional implementation manner of the embodiment of the application, through reasonably selecting each lens and reasonably setting related parameters of each lens, the field angle of the lens can reach 80-90 degrees, namely, 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 large field angle, the distortion of the full field is less than 0.8%. Therefore, the optical lens provided by the embodiment of the application can realize large-field low-distortion imaging.

According to the above embodiments, each lens in the optical lens is disposed, and schematic diagrams representing the imaging effect of the lens as shown in fig. 3, 4 and 5 can be obtained.

As shown in fig. 3, the optical Modulation transfer function of the lens under normal temperature and pressure conditions is shown, wherein the Modulation transfer function (Modulation TransferFunction, MTF) refers to the relationship between the Modulation degree and the logarithm of lines per millimeter in an image, and is used for evaluating the scene detail reduction capability. The modulation degree is the ratio of the difference between the maximum intensity and the minimum intensity to the sum of the maximum intensity and the minimum intensity. The MTF is the ratio of the modulation of an image to the modulation of an object and is a function of the spatial frequency, which is typically expressed in lp/mm. The modulation transfer function may be used to characterize the optical system, with a larger MTF indicating a better imaging quality of the system.

In FIG. 3, the abscissa represents spatial frequency in lp/mm; the ordinate indicates the modulation degree. The optical lens provided by the embodiment of the application has the following requirements on MTF: the MTF of the central view field is more than or equal to 35% @145lp/mm, and the MTF of the edge view field is more than or equal to 10% @145lp/mm. The uppermost curve in the MTF plot is the MTF curve for the central field of view, and it can be seen that at 145lp/mm, the MTF for the central field of view is > 35%. The bottom curve in the MTF plot is the MTF curve for the edge field of view, and it can be seen that at 145lp/mm, the MTF for the edge field of view is > 10%. 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 graph of an optical lens according to an embodiment of the present application. In the figure, the abscissa indicates relative distortion, the unit is; the ordinate indicates 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 by the embodiment of the application is less than 0.8%, so that the design requirement can be met.

Fig. 5 is an image plane relative illuminance diagram of an optical lens according to an embodiment of the present application. As shown in fig. 5, the abscissa represents the field angle; the ordinate indicates 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 surface in the whole view field range is more than or equal to 50 percent.

As can be seen from FIG. 5, the relative illuminance of the image plane of the optical lens provided by the embodiment of the application in the whole view field range is more than 50%, so that the design requirement can be met.

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.

By way of example, the image capturing component may comprise a monocular camera, a binocular camera, a 3D camera, a video camera, or the like, without specific limitation herein.

The foregoing is merely illustrative of the specific embodiments of this application and any equivalent variations and modifications can be made by those skilled in the art without departing from the spirit and principles of this application.

Claims

1. An optical lens is characterized by comprising a reverse telephoto lens group and a rear lens group which are coaxially arranged in sequence 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 is a first negative lens group and a second positive lens group which are sequentially arranged; the first negative lens group is a first negative lens and a second positive lens which are sequentially arranged, and the second positive lens group is a third negative lens and a fourth positive lens which are sequentially arranged; the rear lens group is a fifth positive lens and a sixth positive lens which are sequentially arranged;

the first negative lens and the second positive lens are spherical lenses or aspheric lenses, and the third negative lens, the fourth positive lens, the fifth positive lens and the sixth positive lens are aspheric lenses.

2. The optical lens of claim 1, further comprising a stop disposed between the anti-telephoto lens group and the rear lens group.

3. The optical lens according to claim 2, wherein the aperture of the diaphragm is: 5 mm-9 mm.

4. An optical lens according to claim 1, 2 or 3, wherein the distance between the anti-telephoto lens group and the rear lens group is 2mm to 13mm; 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 or 3, wherein 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 mm-17 mm; the focal length of the rear lens group is 6 mm-17 mm.

6. The optical lens of claim 5, wherein 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. The optical lens of claim 6, wherein the focal length of the third negative lens is-30 mm to-34 mm; the focal length of the fourth positive lens is 10 mm-14 mm; the distance between the third negative lens and the fourth positive lens ranges from 3mm to 6mm.

8. The optical lens of claim 7, wherein the focal length of the fifth positive lens is 31mm to 35mm; the focal length of the sixth positive lens is 18-22 mm; the distance between the fifth positive lens and the sixth positive lens is 2 mm-7 mm.

9. The optical lens of claim 8, wherein 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 aspherical lenses made of optical plastic.

10. An image acquisition component comprising an optical lens according to any one of claims 1 to 9.