CN116794914A

CN116794914A - Imaging system and video monitoring equipment

Info

Publication number: CN116794914A
Application number: CN202210255953.7A
Authority: CN
Inventors: 杨昆; 赵友水; 徐秀宾; 石昌寿
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-03-15
Filing date: 2022-03-15
Publication date: 2023-09-22
Also published as: WO2023173863A1

Abstract

The application discloses an imaging system and video monitoring equipment, and belongs to the technical field of video monitoring. The imaging system includes: an imaging lens and a first concave mirror. The first concave reflector is positioned in the visual field range of the imaging lens, and the first reflecting surface of the first concave reflector faces the imaging lens. The curvature of the first region on the first reflective surface is smaller than the curvature of the second region on the first reflective surface. The distance from the first region to the imaging lens is greater than the distance from the second region to the imaging lens. The first concave mirror is located on a first side of the target surface. The first concave mirror is used for reflecting incident light rays from the second side of the target surface to the imaging lens. The target surface is a plane passing through the main optical axis of the imaging lens. The imaging lens is used for imaging based on the reflected light from the first concave reflecting mirror. According to the imaging system, on the premise that a single imaging lens is adopted, the shooting angle range of a close range is not required to be sacrificed, and the shooting distance of the imaging system can be increased.

Description

Imaging system and video monitoring equipment

Technical Field

The present application relates to the field of video monitoring technologies, and in particular, to an imaging system and a video monitoring device.

Background

The video monitoring technology is widely applied to the fields of security management, road traffic, national defense safety, environmental protection, forest fire prevention and the like. The video monitoring device may also be referred to as an image acquisition device, for example, a camera or the like. The video monitoring device is used for collecting video images of the monitored area. Based on the principle of lens imaging, for the same object, if the object is far away from the lens, the imaging of the object in the imaging picture of the lens is smaller. Therefore, the video monitoring device adopting a single lens often has difficulty in collecting details of monitoring objects which are far away from the video monitoring device in a monitoring area, so that the monitoring distance of the video monitoring device is limited.

Disclosure of Invention

The application provides an imaging system and video monitoring equipment, which can solve the problem that the effective monitoring range of the existing video monitoring equipment is limited.

In a first aspect, an imaging system is provided. The imaging system includes: an imaging lens and a first concave mirror. The first concave reflector is positioned in the visual field range of the imaging lens, and the first reflecting surface of the first concave reflector faces the imaging lens. The curvature of the first region on the first reflective surface is smaller than the curvature of the second region on the first reflective surface. The distance from the first region to the imaging lens is greater than the distance from the second region to the imaging lens. The first concave mirror is located on a first side of the target surface. The first concave mirror is used for reflecting incident light rays from the second side of the target surface to the imaging lens. The target surface is a plane passing through the main optical axis of the imaging lens. The imaging lens is used for imaging based on the reflected light from the first concave reflecting mirror.

The concave mirror has a converging effect on light, and the smaller the curvature of the reflecting position is, the more obvious the converging effect is, so that the image reflected by the area with larger curvature has a smaller reduction degree compared with the object image, and the image reflected by the area with smaller curvature has a larger reduction degree compared with the object image. That is, for the same object, the imaging after reflection via the region of greater curvature is greater than the imaging after reflection via the region of lesser curvature.

In the imaging system provided by the application, image light rays of an object which is positioned in a shooting area and is close to the imaging system can be incident to an area (an area with smaller curvature) of the concave reflecting mirror, which is far away from the imaging lens, and image light rays of an object which is positioned in the shooting area and is far away from the imaging system can be incident to an area (an area with larger curvature) of the concave reflecting mirror, which is close to the imaging lens. The imaging of the object farther in the shooting area is smaller than the imaging of the object nearer in the shooting area, so that the imaging size of the object farther in the finally obtained video image is basically consistent with the imaging size of the object nearer in the video image, that is, the number of pixels included in the imaging of the object farther in the video image is approximately the same as the number of pixels included in the imaging of the object nearer in the video image. Therefore, the imaging definition of a far object and the imaging definition of a near object tend to be consistent in one frame of video image. Therefore, the imaging system provided by the application does not need to sacrifice the shooting angle range of the near distance on the premise of adopting a single imaging lens, for example, the imaging lens with a shorter focal length can be selected to ensure that the near distance has a larger shooting angle range, and then the imaging proportion of a far object and a near object is regulated by the concave reflector, so that the shooting angle range of the far distance is basically the same as the shooting angle range of the near distance, thereby improving the imaging definition of the far object and further improving the shooting distance of the imaging system. In addition, the imaging system provided by the application only needs to adopt one imaging lens, and the hardware cost is low. The imaging lens acquires one path of video stream aiming at the shooting area, the transmission and storage cost of the one path of video stream is lower than that of the multipath video stream, and related personnel can watch the image of the whole shooting area through the one path of video stream without switching the video stream, so that the operation convenience is improved.

Optionally, the first concave mirror is configured to reflect incident light from the second side of the target surface from the first side of the target surface into the imaging lens.

Optionally, the imaging lens includes a first imaging sensor, and the first imaging sensor is located on a second side of the target surface. The first imaging sensor is used for imaging based on the reflected light from the first concave reflector.

In the application, since the first concave reflector is used for reflecting the incident light from the second side of the target surface from the first side of the target surface to enter the imaging lens, based on the lens imaging principle, the light enters the imaging lens from the first side of the target surface and finally is imaged on the second side of the target surface, so that the imaging sensor can be arranged on the second side of the target surface to image the reflected light of the first concave reflector.

Optionally, the imaging system further comprises: a second concave mirror. The second concave reflector is positioned in the visual field range of the imaging lens, and the second reflecting surface of the second concave reflector faces the imaging lens. The curvature of the third region on the second reflective surface is smaller than the curvature of the fourth region on the second reflective surface. The distance from the third region to the imaging lens is greater than the distance from the fourth region to the imaging lens. The second concave mirror is located on a second side of the target surface. The second concave mirror is configured to reflect incident light from the first side of the target surface from the second side of the target surface into the imaging lens. The imaging lens is also used for imaging based on the reflected light from the second concave reflecting mirror.

The function and structure of the second concave mirror may be referred to the function and structure of the first concave mirror.

The first concave reflecting mirror is used for reflecting the incident light rays from the second side of the target surface to the imaging lens, and the second concave reflecting mirror is used for reflecting the incident light rays from the first side of the target surface to the imaging lens, so that the imaging system provided by the application can realize video image acquisition on two shooting areas with different directions simultaneously by adopting a single imaging lens, thereby not only improving the shooting distance of the shooting area on one side, but also expanding the shooting range and enabling the coverage range of the imaging system to be wider.

Optionally, the imaging lens includes a second imaging sensor, the second imaging sensor being located on the first side of the target surface. The second imaging sensor is for imaging based on reflected light from the second concave mirror.

In the application, since the second concave reflecting mirror is used for reflecting the incident light from the first side of the target surface from the second side of the target surface to the imaging lens, based on the lens imaging principle, the light is finally imaged on the first side of the target surface after entering the imaging lens from the second side of the target surface, and therefore, the imaging sensor can be arranged on the second side of the target surface to image the reflected light of the first concave reflecting mirror.

Optionally, the second concave mirror is symmetrical with the first concave mirror about the primary optical axis. This design may reduce the aberrations of the imaging system to some extent.

Optionally, the first concave reflecting mirror and the second concave reflecting mirror are in an integrated structure, and the length A of the imaging lens in the main optical axis direction and the distance B from the integrated structure to the imaging lens along the main optical axis direction satisfy the following conditions: A/B is more than or equal to 1.3 and less than or equal to 1.7. The design can enable the overall imaging definition of the imaging system to be higher, and enable the imaging lens to achieve a better aberration correction effect.

Optionally, the imaging system further includes a housing, the imaging lens and the first concave mirror are fixedly disposed in the housing, a window is disposed on the housing, the window is located on a first side of the target surface, and the first concave mirror is used for reflecting incident light passing through the window to the imaging lens.

Optionally, another window may be disposed on the housing on the second side of the target surface, and the second concave mirror is configured to reflect the incident light passing through the window to the imaging lens.

Optionally, the first concave mirror is a concave spherical mirror, a concave aspherical mirror or a concave freeform mirror. The first concave reflector adopts an aspheric surface type or a free curved surface type, so that the first concave reflector has higher curvature freedom degree, distortion generated by reducing an object image is reduced, and the imaging image quality of an imaging system is improved.

Optionally, the first concave reflector is made of glass or plastic.

Optionally, the second concave mirror is a concave spherical mirror, a concave aspherical mirror, or a concave freeform mirror. The second concave reflector adopts an aspheric surface type or a free curved surface type, so that the second concave reflector has higher curvature degree of freedom, distortion caused by object image reduction is reduced, and the imaging image quality of an imaging system is improved.

Optionally, the second concave reflector is made of glass or plastic.

In a second aspect, there is provided a video surveillance apparatus comprising an imaging system as described in any of the first aspects.

Drawings

FIG. 1 is a schematic diagram of an imaging system according to an embodiment of the present application;

FIG. 2 is a front view of a concave mirror provided in an embodiment of the present application;

FIG. 3 is a schematic deployment diagram of an imaging system provided by an embodiment of the present application;

FIG. 4 is a schematic diagram of a video image according to an embodiment of the present application;

FIG. 5 is a schematic diagram of another imaging system according to an embodiment of the present application;

FIG. 6 is a schematic diagram of yet another imaging system provided in accordance with an embodiment of the present application;

FIG. 7 is a schematic diagram of an imaging system according to another embodiment of the present application;

FIG. 8 is a schematic illustration of another video image provided by an embodiment of the present application;

FIG. 9 is a schematic diagram of another imaging system according to another embodiment of the present application;

fig. 10 is a schematic structural view of yet another imaging system according to another embodiment of the present application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.

The imaging lens related to the embodiment of the application is realized based on a lens imaging principle.

The focal length of an imaging lens, i.e., the number of lens millimeters, refers to the distance from the optical center of the lens to the focal point at which light is focused when parallel light is incident. The length of the focal length of the lens determines the imaging size of the imaging lens on the photographed object. The longer the focal length of the lens, the larger the imaging of the object in the imaging picture of the imaging lens, and the more pixels the imaging of the object contains. Conversely, the shorter the focal length of the lens, the smaller the imaging of the object in the imaging picture of the imaging lens, and the fewer pixels included in the imaging of the object.

The field angle of the imaging lens refers to the maximum angle range that the imaging lens can shoot. The size of the field angle determines the field of view of the imaging lens. The larger the field angle, the larger the field range of the imaging lens. Conversely, the smaller the angle of view, the smaller the field of view of the imaging lens.

Since the pixel size and pixel resolution of the imaging sensor in the imaging lens are both fixed, that is, the size of the imaging frame of the imaging lens is fixed, the longer the lens focal length of the imaging lens, the more pixels the same object contains in the imaging frame of the imaging lens, and the farther the maximum shooting distance of the imaging lens, the smaller the field angle of the imaging lens. Conversely, the shorter the lens focal length of the imaging lens, the fewer pixels included in the imaging of the same object in the imaging picture of the imaging lens, the closer the maximum shooting distance of the imaging lens, and the larger the field angle of the imaging lens. The maximum shooting distance of the imaging lens can be understood as the distance from the farthest object which can be clearly shot by the imaging lens to the imaging lens. The more pixels the imaging of the object in the imaging frame contains, the more clear the object is imaged.

At present, when video monitoring equipment is installed, a proper imaging lens is required to be selected according to actual application scenes. For example, for video monitoring equipment installed in a large area such as a hall or a square, a short focal length lens, for example, a 4 millimeter (mm) lens, can be selected to ensure a larger monitoring angle (i.e., a field angle) so that the monitoring coverage range is wider. For example, for video monitoring equipment installed in long and narrow areas (i.e. depth monitoring scenes) such as hallways, aisles, roads and the like, long-focal-length lenses, such as 8mm lenses, 16mm lenses and the like, can be selected to ensure a far monitoring distance, so that imaging of remote monitoring objects is clear (i.e. imaging comprises more pixels). For example, table 1 shows the numerical relationship between the lens size, the monitoring angle, and the monitoring distance.

TABLE 1

Lens size

2.8mm

4mm

6mm

8mm

12mm

16mm

Monitoring angle

75°

70°

50°

38.5°

26.2°

19.8°

Monitoring distance

About 3 meters

About 6 meters

About 10 meters

About 20 meters

About 35 m

About 50 meters

Most video surveillance devices typically employ a single lens. Based on the principle of lens imaging, if an object is far away from the lens, the imaging of the object in an imaging picture of the lens is smaller. For example, in a road monitoring scene, in a video image collected by a video monitoring device, license plate images of a near vehicle are larger, that is, license plate images of the near vehicle contain more pixels, and license plate images of a far vehicle are smaller, that is, license plate images of the far vehicle contain fewer pixels, so that the license plate number of the far vehicle may not be accurately identified based on the video image collected by the video monitoring device, and the monitoring distance of the video monitoring device is limited. At present, aiming at a depth monitoring scene such as a road monitoring scene, if the monitoring distance of video monitoring equipment is required to be increased, only the monitoring angle can be sacrificed, for example, an imaging lens with a longer focal length is selected. However, the monitoring angle range of the video monitoring device is too small, and more monitoring dead angles exist.

In the related art, a plurality of lenses are integrated in one video monitoring device, the plurality of lenses are respectively selected to have different focal lengths, the lens with a short focal length is used for collecting imaging of objects with a relatively short distance in a monitoring area, and the lens with a long focal length is used for collecting imaging of objects with a relatively long distance in the monitoring area, so that the video monitoring device can have a relatively large monitoring angle range and a relatively large monitoring distance. However, when multiple lenses are adopted to collect video images of the same monitoring area, multiple paths of video streams can be generated, on one hand, the transmission and storage costs of the multiple paths of video streams are high, on the other hand, when related personnel check the video streams of the monitoring area, the video streams collected by different lenses need to be switched back and forth, the operation is complex, and on the other hand, the hardware cost of integrating multiple lenses in one video monitoring device is high.

The embodiment of the application provides an imaging system, which is characterized in that through the matching of an imaging lens and a concave reflector, light rays from a shooting area are reflected to the imaging lens by the concave reflector, and then the imaging lens images the reflected light rays. The reflecting surface of the concave reflecting mirror faces the imaging lens, and the curvature of the area, away from the imaging lens, of the reflecting surface is smaller than that of the area, close to the imaging lens, of the reflecting surface. The concave mirror is located on one side of a plane passing through the main optical axis of the imaging lens, and the photographing region of the imaging system is located on the other side of the plane. Curvature is the inverse of the radius of curvature. The reflecting surface of the concave reflecting mirror in the embodiment of the application is a concave surface. The curvature is used to reflect the degree of curvature of the concave surface. The greater the curvature, the greater the degree of curvature of the concave surface.

Because the concave reflector has a converging effect on light rays, and the smaller the curvature of the reflecting position is, the more obvious the converging effect is, so that the imaging after being reflected by the area with larger curvature is relatively smaller than the reduction degree of the object image, and the imaging after being reflected by the area with smaller curvature is relatively larger than the reduction degree of the object image. That is, for the same object, the imaging after reflection via the region of greater curvature is greater than the imaging after reflection via the region of lesser curvature. According to the structure of the imaging system provided by the embodiment of the application, the image light of the object located in the shooting area and close to the imaging system can be incident to the area (the area with smaller curvature) of the concave reflector away from the imaging lens, and the image light of the object located in the shooting area and further away from the imaging system can be incident to the area (the area with larger curvature) of the concave reflector close to the imaging lens. The imaging of the object farther in the shooting area is smaller than the imaging of the object nearer in the shooting area, so that the imaging size of the object farther in the finally obtained video image is basically consistent with the imaging size of the object nearer in the video image, that is, the number of pixels included in the imaging of the object farther in the video image is approximately the same as the number of pixels included in the imaging of the object nearer in the video image. Therefore, the imaging definition of a far object and the imaging definition of a near object tend to be consistent in one frame of video image. Therefore, on the premise of adopting a single imaging lens, the imaging system provided by the embodiment of the application does not need to sacrifice the shooting angle range of a close range, for example, an imaging lens with a shorter focal length can be selected to ensure that the close range has a larger shooting angle range, and then the imaging proportion of a far object and a near object is regulated by the concave reflector, so that the shooting angle range of the far distance is basically the same as the shooting angle range of the close range, thereby improving the imaging definition of the far object and further improving the shooting distance of the imaging system. In addition, the imaging system provided by the embodiment of the application only needs to adopt one imaging lens, and the hardware cost is low. The imaging lens acquires one path of video stream aiming at the shooting area, the transmission and storage cost of the one path of video stream is lower than that of the multipath video stream, and related personnel can watch the image of the whole shooting area through the one path of video stream without switching the video stream, so that the operation convenience is improved.

The following exemplifies the structure of an imaging system provided by an embodiment of the present application.

For example, fig. 1 is a schematic structural diagram of an imaging system according to an embodiment of the present application. As shown in fig. 1, the imaging system 00 includes: an imaging lens 10 and a first concave mirror 21. The first concave mirror 21 is located within the field of view of the imaging lens 10, and the reflecting surface of the first concave mirror 21 faces the imaging lens 10. The reflecting surface of the first concave reflecting mirror 21 is referred to as a first reflecting surface in the embodiment of the present application. The curvature of the first region M on the first reflective surface is smaller than the curvature of the second region N on the first reflective surface. The distance from the first region M to the imaging lens 10 is greater than the distance from the second region N to the imaging lens 10.

Alternatively, the first reflecting surface is divided into a plurality of regions sequentially arranged in a direction from far to near to the imaging lens 10, and the curvatures of the plurality of regions sequentially increase in the arrangement direction (i.e., the direction from far to near to the imaging lens 10). The first region M and the second region N are any two regions satisfying a distance condition among the plurality of regions.

For example, fig. 2 is a front view of a first concave mirror provided by an embodiment of the present application. As shown in fig. 2, the reflective surface of the first concave mirror has regions 1-4. The curvature of region 1 is less than the curvature of region 2, the curvature of region 2 is less than the curvature of region 3, and the curvature of region 3 is less than the curvature of region 4. When the imaging system is assembled, the reflecting surface of the first concave reflecting mirror faces the imaging lens, the areas 1-4 are arranged in a direction from far to near to the imaging lens, and then the first concave reflecting mirror is fixedly arranged relative to the imaging lens.

The number of the areas divided on the reflecting surface of the first concave reflecting mirror is not limited in the embodiment of the application. The more the number of divided areas on the reflecting surface of the first concave mirror, the more gentle the curvature change of the reflecting surface can be made. For example, in practical design, the curvature of the reflecting surface of the first concave mirror may be gradually increased in a direction from far to near from the imaging lens, so that the number of areas divided on the reflecting surface of the first concave mirror tends to be infinite. Through the curvature design to the reflecting surface of first concave mirror for first concave mirror can adjust the imaging proportion of distant object and near object, so that imaging system's shooting angle scope is the same with near shooting angle scope basically at the long-distance, helps realizing that same object when the different positions in imaging system's shooting region, the formation of image size in imaging lens's the formation of image picture tends to unanimous, and then improves the formation of image definition of distant object in the shooting region, promotes imaging system's shooting distance.

With continued reference to fig. 1, the first concave mirror 21 is located on a first side of the target surface. The first concave mirror 21 is for reflecting incident light from the second side of the target surface to the imaging lens 10. The target surface is a plane passing through the main optical axis L of the imaging lens 10. The first side of the target surface and the second side of the target surface refer to opposite sides of the target surface. The target surface is not directly shown in fig. 1. The object plane can be regarded as a plane passing through the main optical axis L of the imaging lens 10 and perpendicular to the paper surface, that is, the orthographic projection of the object plane on the paper surface coincides with the main optical axis L of the imaging lens 10 shown in fig. 1. The imaging lens 10 is for imaging based on the reflected light from the first concave mirror 21.

With continued reference to fig. 1, an imaging system provided in an embodiment of the present application has a photographing region 1. The photographing region 1 is located at a second side of the target surface. The first concave mirror 21 is used to reflect the image light of the photographing region 1 to the imaging lens 10. The imaging lens 10 is for imaging the photographing region 1 based on the reflected light from the first concave mirror 21.

For example, fig. 3 is a schematic deployment diagram of an imaging system according to an embodiment of the present application. It is assumed that the imaging system is applied to road monitoring scenes. As shown in fig. 3, the imaging system 00 is mounted on the mast 01. The imaging system 00 is pitched downward by a certain angle to shoot the monitored area. Referring to fig. 3, there are a vehicle a and a vehicle b within the monitoring area of the imaging system 00, and the distance from the vehicle a to the imaging system 00 is greater than the distance from the vehicle b to the imaging system 00.

As another example, fig. 4 is a schematic diagram of a video image acquired by the imaging system 00 shown in fig. 3 for a monitored area. As shown in fig. 4, the video image includes an image of the vehicle a and an image of the vehicle b. As can be seen from fig. 4, the imaging system 00 is substantially uniform in the imaging angle ranges of different depths, and therefore the reduction ratio of the imaging of the vehicle a with respect to the object image is substantially the same as the reduction ratio of the imaging of the vehicle b with respect to the object image, that is, the imaging definition of the far vehicle a is substantially the same as the imaging definition of the near vehicle b. The depth here refers to the distance of the photographic subject to the imaging system 00.

Optionally, with continued reference to fig. 1, the imaging lens 10 includes a front group 11, an aperture stop 12, a rear group 13, and an imaging sensor 14. The aperture stop 12 is located between the front group 11 and the rear group 13. After entering the imaging lens 10, the light is transmitted through the front group 11, the aperture diaphragm 12 and the rear group 13 in sequence, and finally imaged by the imaging sensor 14. Wherein the front group 11 includes, but is not limited to, a spherical lens, an aspherical lens, or a cemented lens. The rear group 13 includes, but is not limited to, a spherical lens, an aspherical lens, or a cemented lens. Optionally, the spherical lens is made of glass or plastic. The aspheric lens is made of glass or plastic. The lenses in the front group 11 and the rear group 13 are arranged according to design requirements so that the front group 11 and the rear group 13 can achieve aberration correction by a combination of internal lenses. The aperture stop 12 is used to block the ineffective light entering the imaging lens 10 and pass the effective light from the photographing region to improve the imaging contrast of the imaging sensor 14.

Optionally, the first concave mirror is a concave spherical mirror, a concave aspherical mirror or a concave freeform mirror. The first concave reflector adopts an aspheric surface type or a free curved surface type, so that the first concave reflector has higher curvature freedom degree, distortion generated by reducing an object image is reduced, and the imaging image quality of an imaging system is improved. Optionally, the first concave reflector is made of glass or plastic.

In the imaging system 00 shown in fig. 1, the focal length f of the imaging system 00, the focal length f1 of the first concave mirror 21, and the focal length f2 of the imaging lens 10 satisfy: 1/f=1/f1+1/f 2. The focal length f1 of the first concave reflecting mirror 21 is different from the focal length f2 of the imaging lens 10 in sign, and the focal length f of the imaging system 00 is the same as the focal length f2 of the imaging lens 10 in sign.

Optionally, with continued reference to fig. 1, the first concave mirror 21 is configured to reflect incident light from the second side of the target surface from the first side of the target surface into the imaging lens 10. Based on the lens imaging principle, after entering the imaging lens 10 from the first side of the target surface, the light is sequentially transmitted through the front group 11, the aperture stop 12 and the rear group 13, and finally imaged on the second side of the target surface. That is, in the imaging system shown in fig. 1, the photographing region 1 is finally imaged at the second side portion of the imaging sensor 14 located at the target surface.

Since the photographing region 1 is imaged only on the second side of the target surface, an imaging sensor may be provided only on the second side of the target surface. For example, fig. 5 is a schematic structural diagram of another imaging system according to an embodiment of the present application. As shown in fig. 5, the imaging lens 10 includes a first imaging sensor 141 located on a second side of the target surface. The first concave mirror 21 is configured to reflect incident light from the second side of the target surface from the first side of the target surface into the imaging lens 10. The first imaging sensor 141 is for imaging based on the reflected light from the first concave mirror 10. The remaining structures in the imaging system 00 shown in fig. 5 may refer to corresponding structures in the imaging system 00 shown in fig. 1, and the embodiments of the present application will not be described herein.

Alternatively, the imaging system provided by the embodiment of the application may be a unitary structure. For example, fig. 6 is a schematic structural diagram of yet another imaging system according to an embodiment of the present application. As shown in fig. 6, the imaging system 00 further includes a housing 30 on the basis of the imaging system 00 shown in fig. 1. The imaging lens 10 and the first concave mirror 21 are fixedly disposed within the housing 30. The housing 30 is provided with a viewing window 41. The viewing window 41 is located on a first side of the target surface. The first concave mirror 21 is used to reflect the incident light passing through the viewing window 41 to the imaging lens 10. The position of the window 41 may be determined according to the optical path from the photographing region 1 of the imaging system 00 to the first concave mirror 21 of the imaging system 00 so that the light from the photographing region 1 may be incident on the first concave mirror 21. The position of the window 41 may be determined, for example, in conjunction with the actual installation height of the imaging system 00, the actual installation angle, the relative position of the photographing region 1 and the imaging system 00, and the like.

Alternatively, the first concave mirror 21 is fixedly arranged in the housing 30 by means of a structural element or by means of gluing. The imaging lens 10 is fixedly disposed in the housing 30 by means of a structural member or an adhesive.

The imaging system provided by the embodiment of the application adopts a single imaging lens, does not need to sacrifice the shooting angle range of a short distance, for example, the imaging lens with a shorter focal length can be selected to ensure that the short distance has a larger shooting angle range, and then the imaging proportion of a far object and a near object in the shooting area 1 is regulated by the first concave reflector, so that the shooting angle range of the far distance is basically the same as the shooting angle range of the short distance, thereby improving the imaging definition of the far object and further improving the shooting distance of the imaging system. In addition, the imaging system provided by the embodiment of the application only needs to adopt one imaging lens, so that the hardware cost is lower. The imaging lens acquires one path of video stream aiming at the shooting area, the transmission and storage cost of the one path of video stream is lower than that of the multipath video stream, and related personnel can watch the image of the whole shooting area through the one path of video stream without switching the video stream, so that the operation convenience is improved.

In the imaging system as shown in fig. 1, 5 and 6, when the first concave mirror 21 is used to reflect incident light from the second side of the target surface from the first side of the target surface into the imaging lens 10, the photographing region 1 is imaged only on the imaging sensor located on the second side of the target surface. In this case, another concave mirror for reflecting incident light from the first side of the target surface from the second side of the target surface into the imaging lens 10 to image the photographing region 2 located at the second side of the target surface on the imaging sensor located at the second side of the target surface may also be disposed at the second side of the target surface.

For example, fig. 7 is a schematic structural diagram of an imaging system according to another embodiment of the present application. As shown in fig. 7, on the basis of the imaging system 00 shown in fig. 1, the imaging system 00 further includes: a second concave mirror 22. The second concave mirror 22 is located within the field of view of the imaging lens 10, and the reflecting surface of the second concave mirror 22 faces toward the imaging lens 10. The reflecting surface of the second concave reflecting mirror 22 is referred to as a second reflecting surface in the embodiment of the present application. The curvature of the third region P on the second reflective surface is smaller than the curvature of the fourth region Q on the second reflective surface. The distance from the third region P to the imaging lens 10 is greater than the distance from the fourth region Q to the imaging lens.

Alternatively, the second reflecting surface is divided into a plurality of regions sequentially arranged in a direction from far to near to the imaging lens 10, and the curvatures of the plurality of regions sequentially increase in the arrangement direction (i.e., the direction from far to near to the imaging lens 10). The third region P and the fourth region Q are any two regions satisfying the distance condition among the plurality of regions. The structure of the second concave mirror may refer to the structure of the first concave mirror shown in fig. 2, and the embodiments of the present application are not described herein again.

With continued reference to fig. 7, the second concave mirror 22 is located on the second side of the target surface. The second concave mirror 22 is used to reflect incident light from a first side of the target surface from a second side of the target surface into the imaging lens 10. The imaging lens 10 is also used for imaging based on the reflected light from the second concave mirror 22. The remaining structures in the imaging system 00 shown in fig. 7 may refer to corresponding structures in the imaging system 00 shown in fig. 1, and the embodiments of the present application will not be described herein.

With continued reference to fig. 7, an imaging system provided in an embodiment of the present application has a photographing region 1 and a photographing region 2. The photographing region 1 is located at a second side of the target surface. The photographing region 2 is located at a first side of the target surface. The first concave mirror 21 is used to reflect the image light of the photographing region 1 to the imaging lens 10. The second concave reflecting mirror 22 is used for reflecting the image light of the shooting area 2 to the imaging lens 10. The imaging lens 10 is configured to image the photographing region 1 based on the reflected light from the first concave mirror 21 and to image the photographing region 2 based on the reflected light from the second concave mirror 22, respectively.

Alternatively, the imaging sensor 14 in the imaging system 00 shown in fig. 7 may image the photographing region 1 and the photographing region 2 at the same time. The image light of the photographing region 1 is transmitted to the first concave mirror 21, and the first concave mirror 21 reflects the image light from the first side of the target surface into the imaging lens 10, and after the image light enters the imaging lens 10 from the first side of the target surface, the image light sequentially passes through the front group 11, the aperture stop 12 and the rear group 13, and finally is imaged on the second side of the target surface, that is, the photographing region 1 is finally imaged on the second side portion of the imaging sensor 14 located on the target surface. Similarly, the image light of the shooting area 2 is transmitted to the second concave reflecting mirror 22, the second concave reflecting mirror 22 reflects the image light from the second side of the target surface into the imaging lens 10, and after the image light enters the imaging lens 10 from the second side of the target surface, the image light sequentially passes through the front group 11, the aperture stop 12 and the rear group 13, and finally is imaged on the first side of the target surface, that is, the shooting area 2 is finally imaged on the first side portion of the imaging sensor 14 located on the target surface.

For example, fig. 8 is a schematic diagram of a video image acquired by the imaging system 00 shown in fig. 7. The video image is generated by an imaging sensor. As shown in fig. 8, the video image includes two independent imaging areas, one of which displays a video image corresponding to the photographing area 1 and the other of which displays a video image corresponding to the photographing area 2.

In the imaging system 00 shown in fig. 7, the photographing region 1 and the photographing region 2 are imaged by one imaging sensor 14 at the same time, and thus the frame rate and period of video images acquired for the photographing region 1 and the photographing region 2 by the imaging system 00 shown in fig. 7 are the same.

Alternatively, two independent imaging sensors may be provided in the imaging lens 10, one for imaging the photographing region 1 and the other for imaging the photographing region 2. For example, fig. 9 is a schematic structural diagram of another imaging system according to another embodiment of the present application. As shown in fig. 9, on the basis of the imaging system 00 shown in fig. 5, the imaging system 00 further includes: a second concave mirror 22 and a second imaging sensor 142. That is, in the imaging system 00 shown in fig. 9, the imaging lens 10 includes the first imaging sensor 141 and the second imaging sensor 142. Wherein the first imaging sensor 141 is located at the second side of the target surface, the first imaging sensor 141 is configured to image based on the reflected light from the first concave mirror 10, that is, to image the photographing region 1. The second imaging sensor is located on the first side of the target surface and is used for imaging based on the reflected light from the second concave mirror, i.e. imaging the photographing region 2. The remaining structures in the imaging system 00 shown in fig. 9 may refer to corresponding structures in the imaging system 00 shown in fig. 5, and the embodiments of the present application will not be described herein.

In the imaging system 00 shown in fig. 9, the photographing region 1 is imaged by the first imaging sensor 141, and the photographing region 2 is imaged by the second imaging sensor 142. Since the first imaging sensor 141 and the second imaging sensor 142 are independently imaged, the frame rate and period of the video images acquired by the imaging system 00 as shown in fig. 9 for the photographing region 1 and the photographing region 2 may be the same or may be different. The imaging system 00 shown in fig. 9 has higher flexibility in video image acquisition for the photographing region 1 and the photographing region 2 than the imaging system 00 shown in fig. 7.

Alternatively, the imaging system provided by the embodiment of the application may be a unitary structure. For example, fig. 10 is a schematic structural diagram of yet another imaging system according to another embodiment of the present application. As shown in fig. 10, on the basis of the imaging system 00 shown in fig. 6, the imaging system 00 further includes: a second concave mirror 22 and a viewing window 42. The second concave mirror 22 is fixedly disposed within the housing 30. The housing 30 is provided with a window 41 and a window 42. The viewing window 41 is located on a first side of the target surface. The first concave mirror 21 is used to reflect the incident light passing through the viewing window 41 to the imaging lens 10. The position of the window 41 may be determined according to the optical path from the photographing region 1 of the imaging system 00 to the first concave mirror 21 of the imaging system 00 so that the light from the photographing region 1 may be incident on the first concave mirror 21. The viewing window 41 is located on a second side of the target surface. The second concave mirror 22 is used to reflect the incident light passing through the viewing window 42 to the imaging lens 10. The position of the window 42 may be determined according to the optical path from the photographing region 2 of the imaging system 00 to the second concave mirror 22 of the imaging system 00 so that the light from the photographing region 2 may be incident on the second concave mirror 22. The remaining structures in the imaging system 00 shown in fig. 10 may refer to corresponding structures in the imaging system 00 shown in fig. 6, and the embodiments of the present application will not be described herein.

Optionally, the second concave mirror is a concave spherical mirror, a concave aspherical mirror, or a concave freeform mirror. The second concave reflector adopts an aspheric surface type or a free curved surface type, so that the second concave reflector has higher curvature degree of freedom, distortion caused by object image reduction is reduced, and the imaging image quality of an imaging system is improved. Optionally, the second concave reflector is made of glass or plastic.

Optionally, the second concave mirror 22 is fixedly disposed within the housing 30 by means of a structural member or by gluing.

Alternatively, in the imaging system 00 shown in fig. 7, 9, or 10, the second concave mirror 22 and the first concave mirror 21 are symmetrical with respect to the main optical axis L of the imaging lens 10. That is, the symmetry axes of the first concave mirror 22 and the first concave mirror 21 are on the same line with the main optical axis L of the imaging lens 10. This design can reduce the aberration of the imaging system 00 to some extent. The imaging system in the embodiment of the present application is essentially an optical system. The imaging (optical imaging) of an optical system in actual operation is different from the imaging (paraxial imaging) of paraxial optics (also called gaussian optics) by a certain degree. The deviation of the optical imaging from paraxial imaging is called aberration.

Alternatively, the first concave mirror 21 and the second concave mirror 22 are integrally formed. The length a of the imaging lens 10 in the direction of the main optical axis L and the distance B from the integral structure to the imaging lens 10 along the direction of the main optical axis L satisfy: A/B is more than or equal to 1.3 and less than or equal to 1.7. The length a of the imaging lens 10 in the direction of the main optical axis L is the distance from the light incident surface of the imaging lens 10 to the imaging sensor in the imaging lens 10. Since the second concave mirror 22 and the first concave mirror 21 are symmetrical about the main optical axis L of the imaging lens 10, the integral structure including the first concave mirror 21 and the second concave mirror 22 has a distance B from the imaging lens 10 in the direction of the main optical axis L, that is, a distance from a point on the reflecting surface of the integral structure farthest from the imaging lens 10 to the light incident surface of the imaging lens 10. In designing the imaging system, the length a of the imaging lens 10 in the direction of the main optical axis L and the distance B of the concave mirror to the imaging lens 10 in the direction of the main optical axis L are made to satisfy: the ratio A/B is more than or equal to 1.3 and less than or equal to 1.7, so that the overall imaging definition of the imaging system is higher, and the imaging lens can achieve a better aberration correction effect.

The imaging system provided by the embodiment of the application adopts the single imaging lens to realize the simultaneous video image acquisition of two shooting areas with different directions, thereby not only improving the shooting distance of a single-side shooting area, but also expanding the shooting range and leading the coverage range of the imaging system to be wider.

The embodiment of the application provides video monitoring equipment, which comprises: an imaging system 00 as shown in any of fig. 1, 5-7, and 9-10.

Alternatively, the video monitoring device may be applied to depth monitoring scenes, such as corridor, aisle, road, etc. The video monitoring device can be applied to any other monitoring scene, and the application scene of the video monitoring device is not limited in the embodiment of the application.

The imaging system in the video monitoring equipment provided by the embodiment of the application adopts the single imaging lens, does not need to sacrifice the monitoring angle range of the short distance, for example, the imaging lens with a shorter focal length can be selected to ensure that the short distance has a larger monitoring angle range, and then the concave reflector adjusts the imaging proportion of the far object and the near object in the monitoring area so that the monitoring angle range of the far distance is basically the same as the monitoring angle range of the short distance, thereby improving the imaging definition of the far object, further improving the monitoring distance of the imaging system and enabling the video monitoring equipment to acquire the clear picture of the object farther in the monitoring area. In addition, the imaging system provided by the embodiment of the application only needs to adopt one imaging lens, so that the hardware cost is lower. The imaging lens acquires one path of video stream aiming at the monitoring area, the transmission and storage cost of the one path of video stream is lower than that of the multipath video stream, and related personnel can watch the image of the whole monitoring area through the one path of video stream without switching the video stream, so that the operation convenience is improved.

Furthermore, the imaging system in the video monitoring equipment provided by the embodiment of the application can also adopt a single imaging lens to realize the video image acquisition of two monitoring areas with different directions, thereby not only improving the shooting distance of a single-side monitoring area, but also expanding the monitoring range and leading the monitoring coverage of the video monitoring equipment to be wider.

The terms "first" and "second" and the like in this specification are used for distinguishing between similar elements or the same item having substantially the same function and function, and it should be understood that the elements described in the terms of "first" and "second" and the like do not have a logical or chronological dependency or limitation with respect to the number and order of execution. It will also be understood that, although the description above uses the terms first and second, etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, a first side of the target surface may be referred to as a second side of the target surface, and similarly, a second side of the target surface may be referred to as a first side of the target surface, without departing from the scope of the various described examples. The first side and the second side are only used to distinguish between two different spaces divided by the target surface.

The term "and/or" in the present application is merely an association relation describing the association object, and indicates that three kinds of relations may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

The foregoing description of the preferred embodiments of the present application is not intended to limit the application, but is intended to cover any modifications, equivalents, alternatives, and improvements within the spirit and principles of the application.

Claims

1. An imaging system, comprising: the imaging lens comprises an imaging lens and a first concave reflecting mirror, wherein the first concave reflecting mirror is positioned in the visual field range of the imaging lens, a first reflecting surface of the first concave reflecting mirror faces the imaging lens, the curvature of a first area on the first reflecting surface is smaller than that of a second area on the first reflecting surface, and the distance from the first area to the imaging lens is larger than that from the second area to the imaging lens;

the first concave reflecting mirror is positioned on a first side of a target surface, and is used for reflecting incident light rays from a second side of the target surface to the imaging lens, and the target surface is a plane passing through a main optical axis of the imaging lens;

The imaging lens is used for imaging based on the reflected light from the first concave reflecting mirror.

2. The imaging system of claim 1, wherein the first concave mirror is configured to reflect incident light rays from the second side of the target surface from the first side of the target surface into the imaging lens.

3. The imaging system of claim 2, wherein the imaging lens includes a first imaging sensor located on a second side of the target surface, the first imaging sensor configured to image based on reflected light from the first concave mirror.

4. The imaging system of claim 2 or 3, wherein the imaging system further comprises: a second concave mirror positioned within a field of view of the imaging lens, with a second reflective surface of the second concave mirror facing the imaging lens, a third region on the second reflective surface having a curvature that is less than a curvature of a fourth region on the second reflective surface, the third region being a greater distance from the imaging lens than the fourth region;

The second concave reflector is positioned on a second side of the target surface and is used for reflecting incident light rays from the first side of the target surface from the second side of the target surface to enter the imaging lens;

the imaging lens is also used for imaging based on the reflected light rays from the second concave reflecting mirror.

5. The imaging system of claim 4, wherein the imaging lens includes a second imaging sensor positioned on a first side of the target surface, the second imaging sensor configured to image based on reflected light from the second concave mirror.

6. The imaging system of claim 4 or 5, wherein the second concave mirror is symmetrical with the first concave mirror about the primary optical axis.

7. The imaging system of claim 6, wherein the first concave mirror and the second concave mirror are integrally formed, and a length a of the imaging lens in the main optical axis direction and a distance B from the integrally formed structure to the imaging lens in the main optical axis direction satisfy: A/B is more than or equal to 1.3 and less than or equal to 1.7.

8. The imaging system of any of claims 1 to 7, further comprising a housing, wherein the imaging lens and the first concave mirror are fixedly disposed within the housing, wherein a window is disposed on the housing, wherein the window is disposed on a first side of the target surface, and wherein the first concave mirror is configured to reflect incident light rays passing through the window to the imaging lens.

9. The imaging system of any of claims 1 to 8, wherein the first concave mirror is a concave spherical mirror, a concave aspherical mirror, or a concave freeform mirror.

10. A video monitoring device, comprising: an imaging system as claimed in any one of claims 1 to 9.