CN113167987A

CN113167987A - Optical system, imaging device, and movable platform

Info

Publication number: CN113167987A
Application number: CN202080006474.0A
Authority: CN
Inventors: 毛庆
Original assignee: SZ DJI Technology Co Ltd
Current assignee: SZ DJI Technology Co Ltd
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2021-07-23
Also published as: WO2021253325A1

Abstract

An optical system (100), a photographing device (200), and a movable platform (300), the optical system (100) including a first lens (101), a second lens (102), a third lens (103), a fourth lens (104), a fifth lens (105), a sixth lens (106), and a seventh lens (107) disposed in order from an object side to an image side, the first lens (101) and the fifth lens (105) having negative optical power, the second lens (102), the third lens (103), the fourth lens (104), the sixth lens (106), and the seventh lens (107) having positive optical power; the optical system (100) satisfies the following expression: -8<f₁<‑5，20<f₂<30，16<f₃<24，5<f₄<8，‑8<f₅<‑5，10<f₆<15，70<f₇<90, f/TTL is more than or equal to 0.2 and less than or equal to 0.32; wherein f is the focal length of the optical system (100), f₁To f₇The focal lengths of the first lens (101) to the seventh lens (107) are respectively, and TTL is the distance on the optical axis from the center of the lens surface of the first lens (101) close to the object side to the image plane.

Description

Optical system, imaging device, and movable platform

Technical Field

The present application relates to the field of optical technologies, and in particular, to an optical system, a photographing device using the optical system, and a movable platform.

Background

With the development of technology, a miniaturized lens with high image quality, low cost and wide field of view is more and more favored by people. The large-field-of-view, miniaturized wide-angle lens on the market at present mainly focuses on 1/2.3 of the image sensor size, and if the size of the image sensor needs to be increased, for example, to 1 inch or more, the following problems need to be solved: after the size of the image sensor is increased, if a large aperture is required to be kept used, the depth of field becomes shallow, and macro photography cannot be considered; if the length of the lens is too large, the miniaturization of the product is not facilitated, and the cruising ability of the final product is influenced.

Disclosure of Invention

Based on this, embodiments of the present application provide an optical system, a photographing device, and a movable platform, which facilitate miniaturization of a product while increasing a field angle of the photographing device and improving imaging quality.

In a first aspect, embodiments of the present application provide an optical system including, in order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, the first lens and the fifth lens having negative optical power, the second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens having positive optical power;

the optical system satisfies the following expression:

-8<f₁<-5，20<f₂<30，16<f₃<24，5<f₄<8，-8<f₅<-5，10<f₆<15，70<f₇<90，0.2≤f/TTL≤0.32；

where f is the focal length of the optical system, f₁Is the focal length, f, of the first lens₂Is the focal length of the second lens, f₃Is the focal length of the third lens, f₄Is the focal length of the fourth lens, f₅Is the fifth lensFocal length of (f)₆Is the focal length of the sixth lens, f₇And TTL is an axial distance from the center of the lens surface of the first lens element on the object side to the image plane.

In a second aspect, embodiments of the present application also provide a photographing apparatus including an optical system and an image sensor, the optical system being arranged in an optical path between an object to be photographed and the image sensor;

the optical system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are arranged in sequence from an object side to an image side, wherein the first lens and the fifth lens have negative focal power, and the second lens, the third lens, the fourth lens, the sixth lens and the seventh lens have positive focal power;

the optical system satisfies the following expression:

where f is the focal length of the optical system, f₁Is the focal length, f, of the first lens₂Is the focal length of the second lens, f₃Is the focal length of the third lens, f₄Is the focal length of the fourth lens, f₅Is the focal length of the fifth lens, f₆Is the focal length of the sixth lens, f₇And TTL is an axial distance from the center of the lens surface of the first lens element on the object side to the image plane.

In a third aspect, the present application further provides a movable platform, where the movable platform includes a platform body and a shooting device, and the shooting device is carried on the platform body; the photographing apparatus includes an optical system and an image sensor, the optical system being disposed in an optical path between an object to be photographed and the image sensor;

the optical system satisfies the following expression:

The optical system, the shooting device and the movable platform provided by the embodiment of the application have the advantages that the optical system is installed on the shooting device, the shooting device can be installed on the main body of the movable platform, the optical system utilizes the combination of seven lenses and specific parameter setting, the product size can be reduced, meanwhile, the field angle of the shooting device is increased, and the imaging quality is improved.

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 application.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an optical system according to an embodiment of the present application;

fig. 2 is a schematic configuration diagram of an optical system according to an embodiment of the present application;

FIG. 3 is a schematic diagram of another optical system according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of a further optical system according to an embodiment of the present application;

FIG. 5 is a schematic diagram illustrating an effect of an imaging quality of an optical system provided by an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating an effect of an imaging quality of an optical system provided by an embodiment of the present application;

fig. 7 is a schematic structural diagram of a photographing device according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of a movable platform according to an embodiment of the present application.

Description of the main elements and symbols:

100. an optical system; 101. a first lens; 102. a second lens; 103. a third lens element 104, a fourth lens element; 105. a fifth lens; 106. a sixth lens; 107. a seventh lens; 108. a lens;

200. a photographing device; 22. an object to be photographed; 220. an image of an object to be photographed; 211. a display screen; 212. shooting a key;

300. a movable platform; 310. a platform body.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

It is also to be understood that the terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the specification of the present application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an optical system according to an embodiment of the present disclosure. The optical system can be used for increasing the field angle of the shooting device and simultaneously improving the imaging quality.

As shown in fig. 1, the optical system 100 includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, and a seventh lens 107, which are arranged in order from an object side O to an image side I, wherein the first lens 101 and the fifth lens 105 have negative optical power, and the second lens 102, the third lens 103, the fourth lens 104, the sixth lens 106, and the seventh lens 107 have positive optical power.

Wherein the optical system 100 satisfies the following expression:

-8<f₁<-5，20<f₂<30，16<f₃<24，5<f₄<8，-8<f₅<-5，10<f₆<15，70<f₇<90，0.2≤f/TTL≤0.32 (1)

in expression (1), f is the focal length of the optical system 100, and f₁Is the focal length, f, of the first lens 101₂Is the focal length, f, of the second lens 102₃Is the focal length, f, of the third lens 103₄Is the focal length, f, of the fourth lens 104₅Is the focal length, f, of the fifth lens 105₆Is the focal length, f, of the sixth lens 106₇Is the seventh lens 107The focal length TTL is the distance on the optical axis from the center of the lens surface of the first lens 101 on the object side to the image plane.

The optical system 100 satisfies f/TTL of 0.2 ≦ f/TTL of 0.32, and can ensure miniaturization and lightness of the optical system while keeping the compression ratio of the periphery of the lens corresponding to the optical system 100 small. The smaller compression ratio of the periphery of the lens can ensure that the compression ratio of the periphery picture is smaller, and the optical system can capture more details under the same visual angle.

The optical system configured according to the parameters can be installed on the shooting device to increase the field angle of the shooting device and further shoot a wider scene, and the optical system utilizes the combination of seven lenses and specific parameter setting, thereby not only increasing the field angle of the shooting device and improving the imaging quality, but also reducing the volume of the shooting device. Therefore, the size of the image sensor is convenient to be improved by the shooting device, and the cruising ability of the product is improved by the miniaturization of the shooting device.

Note that the aperture stop S of the optical system 100 is located between the third lens 103 and the fourth lens 104.

In some embodiments, using the above seven lens combination and specific parameter settings, the length of the optical system 100 can be designed to be 20.5 mm; or ensuring that the field angle of the optical system is 155 degrees; still alternatively, the length of the optical system 100 may be designed to be 20.5mm, and the field angle of the optical system may be ensured to be 155 °.

In some embodiments, in order to further improve the imaging quality of the optical system, the seventh lens 107 may be designed to form an inflection point. Specifically, that is, the object side lens surface of the seventh lens 107 has an inflection point, or the image side lens surface of the seventh lens 107 has an inflection point; alternatively, both the object-side lens surface and the image-side lens surface of the seventh lens 107 have inflection points.

Since the seventh lens 107 has an inflection point design, the object-side lens surface of the seventh lens 107 has a convex object-side surface, or the image-side lens surface of the seventh lens 107 has a concave image-side surface, or the object-side lens surface of the seventh lens 107 has a convex object-side surface and the image-side lens surface of the seventh lens 107 has a concave image-side surface.

In some embodiments, in order to further improve the imaging quality of the optical system, the sixth lens 106 may be designed to form an inflection point. Specifically, the object side lens surface of the sixth lens 106 has an inflection point, or the image side lens surface of the sixth lens 106 has an inflection point; alternatively, both the object-side lens surface and the image-side lens surface of the sixth lens 106 have inflection points.

Since the sixth lens element 106 has an inflection design, the object-side lens surface of the sixth lens element 106 has a convex object-side surface, or the image-side lens surface of the sixth lens element 106 has a concave image-side surface, or the object-side lens surface of the sixth lens element 106 has a convex object-side surface and the image-side lens surface of the sixth lens element 106 has a concave image-side surface.

It is noted that in some embodiments, the sixth lens 106 and the seventh lens 107 may both have an inflection design.

In some embodiments, the optical system 100 includes at least one lens made of glass. For example, the first lens 101 is a glass lens, or the fourth lens 104 is a glass lens, or both the first lens 101 and the fourth lens 104 are glass lenses. In order to reduce the weight of the optical system, the optical system 100 includes at least one lens made of plastic. For example, the seventh lens 107 is a plastic lens.

In some embodiments, a greater number of plastic lenses may be employed in order to further reduce the weight of the optical system 100. For example, the first lens 101 is a glass lens, and the second lens 102, the third lens 103, the fourth lens 104, the fifth lens 105, the sixth lens 106, and the seventh lens 107 are plastic lenses; for example, the fourth lens 104 is a glass lens, and the first lens 101, the second lens 102, the third lens 103, the fifth lens 105, the sixth lens 106, and the seventh lens 107 are plastic lenses; for another example, the first lens 101 and the fourth lens 104 are glass lenses, and the second lens 102, the third lens 103, the fifth lens 105, the sixth lens 106, and the seventh lens 107 are plastic lenses.

In some embodiments, the seventh lens 107 is used as a focusing lens, and macro photography can be considered during shooting by using the focusing lens, so that the imaging quality of the optical system is improved. In other embodiments, the seventh lens 107 is used as a focusing lens, and the seventh lens 107 is a plastic lens, so that the weight of the focusing lens can be reduced, thereby further improving the battery life of the photographing device.

In some embodiments, to correct for chromatic aberrations, the imaging quality of the optical system is improved. The optical system 100 satisfies the following expression: v. of₄Not less than 65, wherein v₄The abbe number of the fourth lens 104, also called abbe number. When the abbe number of the fourth lens element 104 is greater than 65, chromatic aberration, especially vertical axis chromatic aberration, can be corrected, thereby improving the imaging quality of the optical system.

In some embodiments, to improve the imaging quality of the optical system, the seventh lens 107 is further defined, that is, the optical system 100 satisfies the following expression: v is more than or equal to 18₇≤25，1.5≤n₇Less than or equal to 1.7, wherein, v₇Is the Abbe number, n, of the seventh lens 107₇Is the refractive index of the seventh lens 107.

At least one of the two lens surfaces of the seventh lens 107 is aspheric, but both lens surfaces may be aspheric. The seventh lens 107 is a focusing lens, so the seventh lens 107 is a plastic lens, which is beneficial to lightening the weight of the focusing lens and reducing the power consumption of a motor during focusing, thereby increasing the battery endurance of the product in a miniaturized product.

In some embodiments, the aberration problem caused by a large wide angle is corrected while the aberration is reduced, so that the imaging quality of the optical system is improved. The optical system 100 satisfies the following expression:

1.7≥n₁≥1.45，v₁≥65；1.9≥n₂≥1.45，v₂≤40；1.58≥n₃≥1.45，v₃≥55；1.9≥n₅≥1.45，v₅≤40；1.58≥n₆≥1.45，v₆≥55 (2)

in the expression (2), n₁、n₂、n₃、n₅、n₆The refractive indexes of the first lens 101, the second lens 102, the third lens 103, the fifth lens 105 and the sixth lens 106 are respectively, and the range of the refractive index values is limited, so that the light is collected at a large visual angle position, and meanwhile, the aberration is reduced, namely, the distortion of an imaging edge is reduced; v. of₁、v₂、v₃、v₅、v₆The dispersion coefficients of the first lens 101, the second lens 102, the third lens 103, the fifth lens 105 and the sixth lens 106 are respectively, and the range of the dispersion coefficient values is limited, which is beneficial to correcting the chromatic aberration problem caused by a large wide angle.

In some embodiments, the optical system 100 satisfies the following expression:

in the expression (3), c₇₁Is the curvature of the object side lens surface of the seventh lens 107, c₇₂Is the curvature of the image side lens surface of the seventh lens 107. The optical system meeting the condition of the expression (3) is beneficial to correcting the angle of emergent rays, better matching with an image sensor, reducing the focusing sensitivity of the lens and still keeping better optical performance under the conditions of high-frequency vibration and falling.

In some embodiments, to ensure spatial arrangement of mechanical structures, stroke of a focus lens, and imaging quality of an optical system, the optical system satisfies the following expression:

CT₆₁＞2.0mm，CT₆₂> 1.9mm, and CT₆₁+CT₇₁＝CT₆₂+CT₇₂ (4)

In expression (4), CT₆₁The distance between the image-side lens surface of the sixth lens element 106 and the object-side lens surface of the seventh lens element 107 at an infinite object distance, CT₆₂The distance between the image-side lens surface of the sixth lens element 106 and the object-side lens surface of the seventh lens element 107 at the closest object distance, CT₇₁Of a seventh lens 107 at infinite object distanceSeparation of image-side lens surface from image plane, CT₇₂Mm represents mm, which is the interval from the image-side lens surface to the image plane of the seventh lens 107 at the closest object distance.

In some embodiments, specifically, CT₆₁＝2.304mm，CT₆₂＝1.900mm，CT₇₁＝2.350mm，CT₇₂2.754mm, where mm denotes millimeters.

In one embodiment, for further correction, one mirror surface or all aspheric lens surfaces of the above aspheric lens are high-order aspheric surfaces, which satisfy the following expression:

in expression (5), z is an aspheric rotational symmetry axis, and c is a vertex curvature; y is a radial coordinate, and the unit of the radial coordinate is the same as the unit length of the lens; k is a conic constant, a₁To a₈Each representing a coefficient corresponding to each radial coordinate.

In some embodiments, in order to improve the imaging quality of the optical system, a filter may be further disposed on the optical system. As shown in fig. 2, the optical system further comprises a lens 108, the lens 108 is disposed between the seventh lens 107 and the image sensor, and specifically, the lens 108 may be an IR lens for imaging in a specific wavelength range.

Specific numerical configurations of the optical system are given below in conjunction with the drawings and tables, and as shown in fig. 3, the numbers of

surfaces

1, 2, ·, and 15 denote surface numbers in the optical system, and respectively denote a mirror surface of the first lens 101, a mirror surface of the second lens 102, a mirror surface of the

seventh lens

107, and 16 denotes a mirror 108.

Specifically, as shown in fig. 3, two lens surfaces of the first lens 101 are surface 1 and surface 2, respectively, two lens surfaces of the second lens 102 are surface 3 and surface 4, respectively, two lens surfaces of the third lens 103 are surface 5 and surface 6, respectively, the aperture stop S is surface 7, two lens surfaces of the fourth lens 104 are surface 8 and surface 9, respectively, two lens surfaces of the fifth lens 105 are surface 10 and surface 11, two lens surfaces of the sixth lens 106 are surface 12 and surface 13, respectively, two lens surfaces of the seventh lens 107 are surface 14 and surface 15, respectively, and the mirror 108 is a flat mirror and is denoted as surface 16.

In tables 1 to 5, the type indicates the shape of the surface, "STANDRAD" indicates a plane, "EVENASPH" indicates an aspherical surface; the radius of curvature represents the degree of curvature of the lens surface, which can be represented by R, the smaller the value of R, the more curved the lens surface; a separation or Thickness (thinness), which is expressed as a separation distance between lenses of an optical system on an optical axis, and a Thickness which is a center Thickness of the lenses; nd represents a refractive index of the lens; vd denotes the abbe number of the lens, also called abbe number; "Infinity" means plane; "CT 6N" denotes a distance between the image side lens surface of the sixth lens 106 and the object side lens surface of the seventh lens 107 at different object distances (infinity and closest); "CT 7N" indicates the image-side lens surface-to-imaging surface interval of the seventh lens element 107 at different object distances (infinity and closest). k is a conic constant, a₁To a₈Each representing a coefficient corresponding to each radial coordinate.

Specific numerical configurations of the different optical systems shown in tables 1, 2, 3, 4 and 5 are shown, and the structures of the corresponding optical systems are shown in fig. 1 or 4, specifically, the optical system shown in fig. 1 is referred to as embodiment one, and the optical system shown in fig. 4 is referred to as embodiment two; specific numerical configurations of the optical systems shown in tables 1, 2, and 6.

Table 1 shows the data of the parameters of the respective surfaces of the optical system of the first embodiment

Table 2 shows aspheric coefficient data of each surface of an optical system according to an embodiment

surf

K

Item 4

Item of 6

8 items

Item

10

1

-15.1325

-9.36605E-05

-1.04496E-06

5.68352E-07

-7.66691E-09

2

-0.67157

8.60735E-04

-3.76988E-05

8.66002E-05

-8.22868E-06

3

74.36007

-2.25644E-04

-4.24418E-05

3.65860E-06

2.34251E-06

4

-58.5037

3.96890E-04

-6.27439E-05

-1.08559E-05

3.70021E-06

5

-1.41259

9.94682E-04

-6.72161E-04

6.37936E-04

-2.24926E-05

6

0.232845

-1.11445E-03

2.37391E-04

4.61223E-05

3.64133E-05

8

-2.90525

1.07605E-03

1.77414E-04

-1.74936E-04

3.33049E-05

9

-0.63971

-1.02225E-03

-2.20757E-04

1.31195E-04

3.34726E-05

10

-11.6463

-3.34333E-03

-3.37290E-04

2.98569E-04

-3.77150E-05

11

0

7.91786E-04

8.83822E-05

-1.27839E-05

-3.02227E-06

12

-28.1604

-1.89093E-03

8.22043E-05

-4.85203E-05

-5.36580E-06

13

-84.035

3.67442E-04

-4.98829E-05

-2.02518E-05

-9.92744E-08

14

4.404447

-8.60813E-04

2.05360E-06

2.95501E-06

-4.73578E-08

15

0

-6.48660E-04

-3.18345E-06

1.34597E-06

-3.78493E-09

Table 3 shows the lens set configuration data of the optical system (embodiment one) when the object distance is infinity

CT0	INF
		CT61	2.304
CT71	2.35

Table 4 shows the lens group configuration data of the optical system (example two) when the object distance is the closest

Table 5 shows the lens set configuration data of an optical system according to an embodiment

Length of optical system	20.5mm
		Angle of view of optical system	155°

Wherein, in table 1, table 3 and table 4, CT0 represents the object distance of the optical system, such as infinity when CT0 is INF or 0.5m when CT0 is 0.5 m; in CT6N and CT7N, N is 1 or 2, 1 represents data at INF, and 2 represents data at 0.5 m.

Fig. 5 and 6 show an exemplary optical system of an embodiment, which has better imaging effect in Field Curvature (Field Curvature) and Distortion (Distortion) at a wavelength of 546nm as shown in fig. 5 and 6.

It should be noted that, two specific embodiments (the optical systems of the first embodiment and the second embodiment) are given above, and it is needless to say that the optical design may be performed after changing one of the parameters, so as to obtain more different optical systems.

Referring to fig. 7, fig. 7 is a schematic structural diagram of a camera according to an embodiment of the present disclosure. The photographing device 200 can realize an imaging effect of a large image plane and high image quality, and can also realize product miniaturization.

As shown in fig. 7, the photographing device 200 includes an optical system 100 and an image sensor, and the optical system 100 is arranged in an optical path between the object 22 to be photographed and the image sensor. The optical system 100 adopts any one of the optical systems provided in the above embodiments, and the image sensor may be, for example, a cmos sensor or a CCD sensor.

Specifically, the shooting device 200 is an electronic device capable of shooting, and includes a mobile phone, a digital camera, a motion camera, a wearable device, or a handheld pan-tilt camera.

In some embodiments, as shown in FIG. 7, the camera 200 may be a motion camera including a display 211 and a capture button 212. The optical system 100 is used to image an object 22 to be photographed (such as a scene) on an image sensor of the photographing device 200; the display screen 211 is used for displaying imaging, for example, displaying an image 220 of an object to be photographed, and the display screen 211 may be a touch display screen; the photographing key 212 is used to trigger photographing.

The imaging device in the above embodiment uses the optical system provided by the embodiment of the present application, so that the field angle of the imaging device can be increased, the imaging quality of the imaging device can be improved, and the miniaturization of the product can be realized.

Please refer to fig. 8, fig. 8 is a schematic structural diagram of a movable platform according to an embodiment of the present application. The movable platform is provided with a shooting device to realize shooting.

As shown in fig. 8, the movable platform 300 includes a platform main body 310 and the photographing device 200, the photographing device 200 is mounted on the platform main body 310, and the photographing device 200 is any one of the photographing devices provided in the above embodiments.

Illustratively, the movable platform 300 includes any one of a drone, a robot, an unmanned vehicle, and a handheld pan/tilt head.

Wherein, this aircraft includes unmanned aerial vehicle, and this unmanned aerial vehicle includes rotor type unmanned aerial vehicle, for example four rotor type unmanned aerial vehicle, six rotor type unmanned aerial vehicle, eight rotor type unmanned aerial vehicle, also can be fixed wing unmanned aerial vehicle, can also be the combination of rotor type and fixed wing unmanned aerial vehicle, does not do the injecing here.

The robot can also be called an educational robot, a Mecanum wheel omnidirectional chassis is used, a plurality of intelligent armors are arranged on the whole body, and each intelligent armor is internally provided with a hitting detection module, so that physical hitting can be rapidly detected. Simultaneously still include the diaxon cloud platform, can rotate in a flexible way, cooperation transmitter accuracy, stability, launch crystal bullet or infrared light beam in succession, cooperation trajectory light efficiency gives the user more real shooting experience.

For example, install optical system on unmanned aerial vehicle, because optical system can increase the angle of vision of camera lens, and then can shoot the scenery on a large scale, can improve shooting device's imaging quality again simultaneously, the combination of a plurality of lenses makes relative distance less moreover, and then has reduced optical system's volume, has realized miniaturization and lightness. From this, when unmanned aerial vehicle is used for taking photo by plane, can shoot better image through using this optical system, and then improved user's experience and felt.

While the invention has been described with reference to specific embodiments, the scope of the invention is not limited thereto, and those skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the invention. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An optical system comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens which are arranged in this order from an object side to an image side, the first lens and the fifth lens having negative refractive power, the second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens having positive refractive power;

the optical system satisfies the following expression:

2. The optical system according to claim 1, wherein an object side lens surface of the seventh lens element has an inflection point, and/or an image side lens surface of the seventh lens element has an inflection point.

3. The optical system according to claim 2, wherein the object side lens surface of the seventh lens has a convex object side surface and/or the image side lens surface of the seventh lens has a concave image side surface.

4. The optical system according to claim 1, wherein an object side lens surface of the sixth lens element has an inflection point, and/or an image side lens surface of the sixth lens element has an inflection point.

5. The optical system according to claim 4, wherein the object side lens surface of the sixth lens has a convex object side surface and/or the image side lens surface of the sixth lens has a concave image side surface.

6. The optical system of claim 1, wherein the optical system comprises at least one lens made of glass.

7. The optical system according to claim 6, characterized in that the first lens is a glass lens and/or the fourth lens is a glass lens.

8. The optical system of claim 1, wherein the seventh lens acts as a focusing lens.

9. The optical system according to claim 1, wherein the third lens and the fourth lens are located on both sides of an aperture stop of the optical system.

10. The optical system according to any one of claims 1 to 9, characterized in that the optical system satisfies the following expression：v₄Not less than 65, wherein v₄Is the abbe number of the fourth lens.

11. The optical system according to any one of claims 1 to 9, characterized in that the optical system satisfies the following expression:

18≤v₇≤25，1.5≤n₇≤1.7

wherein v is₇Is the Abbe number, n, of the seventh lens₇Is the refractive index of the seventh lens.

12. The optical system of claim 11, wherein the seventh lens is a plastic lens.

13. The optical system according to claim 11, wherein at least one of two lens surfaces of the seventh lens is aspherical.

14. The optical system according to any one of claims 1 to 9, characterized in that the optical system satisfies the following expression:

1.7≥n₁≥1.45，v₁≥65；1.9≥n₂≥1.45，v₂≤40；1.58≥n₃≥1.45，v₃≥55；1.9≥n₅≥1.45，v₅≤40；1.58≥n₆≥1.45，v₆≥55；

wherein n is₁、n₂、n₃、n₅、n₆The refractive indexes of the first lens, the second lens, the third lens, the fifth lens and the sixth lens are respectively; v. of₁、v₂、v₃、v₅、v₆The first lens, the second lens, the third lens, the fifth lens and the sixth lens are respectively the dispersion coefficients.

15. The optical system according to any one of claims 1 to 9, characterized in that the optical system satisfies the following expression:

wherein, c₇₁Is a curvature of an object side lens surface of the seventh lens element, c₇₂Is a curvature of an image side lens surface of the seventh lens.

16. The optical system according to any one of claims 1 to 9, characterized in that the optical system satisfies the following expression:

CT₆₁＞2.0mm，CT₆₂> 1.9mm, and CT₆₁+CT₇₁＝CT₆₂+CT₇₂

Wherein, CT₆₁A distance between an image side lens surface of the sixth lens and an object side lens surface of the seventh lens at an infinite object distance, CT₆₂The distance between the image side lens surface of the sixth lens and the object side lens surface of the seventh lens at the closest object distance, CT₇₁The distance between the image side lens surface and the imaging surface of the seventh lens at infinite object distance, CT₇₂Mm represents mm, which is the distance from the image side lens surface to the imaging surface of the seventh lens at the closest object distance.

17. The optical system of claim 16, wherein CT is₆₁＝2.304mm，CT₆₂＝1.900mm，CT₇₁＝2.350mm，CT₇₂2.754mm, where mm denotes millimeters.

18. The optical system according to claim 1, characterized in that the length of the optical system is 20.5mm and/or the angle of field of the optical system is 155 °.

19. A photographing apparatus characterized by comprising an optical system and an image sensor, the optical system being arranged in an optical path of an object to be photographed and the image sensor;

the optical system satisfies the following expression:

20. The imaging device according to claim 19, wherein an object side lens surface of the seventh lens element has an inflection point, and/or an image side lens surface of the seventh lens element has an inflection point.

21. The imaging device according to claim 20, wherein the object side lens surface of the seventh lens has a convex object side surface, and/or wherein the image side lens surface of the seventh lens has a concave image side surface.

22. The imaging device according to claim 19, wherein an object side lens surface of the sixth lens element has an inflection point, and/or an image side lens surface of the sixth lens element has an inflection point.

23. The imaging device according to claim 22, wherein an object-side lens surface of the sixth lens has a convex object-side surface, and/or an image-side lens surface of the sixth lens has a concave image-side surface.

24. The camera of claim 19, wherein the optical system comprises at least one glass lens.

25. The camera of claim 24, wherein the first lens is a glass lens and/or the fourth lens is a glass lens.

26. The camera of claim 19, wherein the seventh lens acts as a focus lens.

27. The imaging apparatus according to claim 19, wherein the third lens and the fourth lens are located on both sides of an aperture stop of the optical system.

28. The photographing device according to any one of claims 19 to 27, wherein the optical system satisfies the following expression: v. of₄Not less than 65, wherein v₄Is the abbe number of the fourth lens.

29. The photographing device according to any one of claims 19 to 27, wherein the optical system satisfies the following expression:

18≤v₇≤25，1.5≤n₇≤1.7

30. The camera of claim 29, wherein the seventh lens is a plastic lens.

31. The camera of claim 29, wherein at least one of two lens surfaces of said seventh lens is aspherical.

32. The photographing device according to any one of claims 19 to 27, wherein the optical system satisfies the following expression:

33. The photographing device according to any one of claims 19 to 27, wherein the optical system satisfies the following expression:

34. The photographing device according to any one of claims 19 to 27, wherein the optical system satisfies the following expression:

CT₆₁＞2.0mm，CT₆₂> 1.9mm, and CT₆₁+CT₇₁＝CT₆₂+CT₇₂

35. The imaging apparatus of claim 34, wherein CT is₆₁＝2.304mm，CT₆₂＝1.900mm，CT₇₁＝2.350mm，CT₇₂2.754mm, where mm denotes millimeters.

36. The camera device according to claim 19, characterized in that the length of the optical system is 20.5mm and/or the angle of field of the optical system is 155 °.

37. A movable platform is characterized by comprising a platform body and a shooting device, wherein the shooting device is carried on the platform body; the photographing apparatus includes an optical system and an image sensor, the optical system being disposed in an optical path between an object to be photographed and the image sensor;

the optical system satisfies the following expression:

38. The movable platform of claim 37, wherein an object side lens surface of the seventh lens element has an inflection point, and/or an image side lens surface of the seventh lens element has an inflection point.

39. The movable platform of claim 38, wherein the object side lens surface of the seventh lens has a convex object side surface and/or the image side lens surface of the seventh lens has a concave image side surface.

40. The movable platform of claim 37, wherein an object side lens surface of the sixth lens element has an inflection point, and/or an image side lens surface of the sixth lens element has an inflection point.

41. The movable platform of claim 40, wherein the object side lens surface of the sixth lens has a convex object side surface and/or the image side lens surface of the sixth lens has a concave image side surface.

42. The movable platform of claim 37, wherein the optical system comprises at least one lens of glass.

43. The movable platform of claim 42, wherein the first lens is a glass lens, and/or the fourth lens is a glass lens.

44. The movable platform of claim 37, wherein the seventh lens acts as a focusing lens.

45. The movable platform of claim 37, wherein the third and fourth lenses are located on either side of an aperture stop of the optical system.

46. A movable platform according to any of claims 37-45 wherein the optical system satisfies the following expression: v. of₄Not less than 65, wherein v₄Is the abbe number of the fourth lens.

47. A movable platform according to any of claims 37-45 wherein the optical system satisfies the following expression:

18≤v₇≤25，1.5≤n₇≤1.7

48. The movable platform of claim 47, wherein the seventh lens is a plastic lens.

49. The movable platform of claim 47, wherein at least one of the two lens surfaces of the seventh lens is aspheric.

50. A movable platform according to any of claims 37-45 wherein the optical system satisfies the following expression:

51. A movable platform according to any of claims 37-45 wherein the optical system satisfies the following expression:

52. A movable platform according to any of claims 37-45 wherein the optical system satisfies the following expression:

CT₆₁＞2.0mm，CT₆₂> 1.9mm, and CT₆₁+CT₇₁＝CT₆₂+CT₇₂

53. The movable platform of claim 52, wherein CT is₆₁＝2.304mm，CT₆₂＝1.900mm，CT₇₁＝2.350mm，CT₇₂2.754mm, where mm denotes millimeters.

54. The movable platform of claim 37, wherein the optical system has a length of 20.5mm and/or a field angle of 155 °.

55. The movable platform of claim 37, wherein the movable platform comprises any one of a drone, a robot, an unmanned vehicle, and a handheld pan-tilt head.