阅读说明：本技术 一种大视场小像差龙虾眼成像系统 (Large-field-of-view small-aberration lobster eye imaging system ) 是由 常军 钟乐 李轶庭 黄翼 姜会林 宋大林 于 2021-06-17 设计创作，主要内容包括：本发明公开了一种大视场小像差龙虾眼成像系统,物镜的每个小眼为微小四棱台,微小四棱台的内壁面形为自由曲面,半球面形物镜可以看作是由互相紧贴但不同半径的立体圆环构成,立体圆环由多个微小四棱台绕一圈形成；从物镜最外围的一圈四棱台到中心的一圈四棱台,小四棱台近球心侧的边长相等,四棱台侧面的夹角逐渐减小,由此可使得物镜的焦距具有一定变化,越靠近中心的微通道焦距越长；由于微通道的焦距变化,物镜在距离为R处的像面是平面而非球面,实现了在大视场范围内对目标的高分辨、多谱段,平面成像,解决系统工作谱段受光学材料限制的问题,有效消除了传统龙虾眼结构成像不可避免的大场曲,减小了系统像差,提高像面能量均匀性,能够有效压缩系统尺寸重量,具有明显提升系统工作能力、实现应用部署的效果。(The invention discloses a large-field-of-view small-aberration lobster eye imaging system.A small eye of an objective lens is a micro quadrangular frustum pyramid, the inner wall surface of the micro quadrangular frustum pyramid is a free-form surface, a hemispherical mirror can be regarded as being formed by three-dimensional circular rings which are tightly attached to each other but have different radiuses, and the three-dimensional circular rings are formed by winding a plurality of micro quadrangular frustum pyramids for one circle; from the circle of quadrangular frustum at the outermost periphery of the objective lens to the circle of quadrangular frustum at the center, the side lengths of the small quadrangular frustum near the spherical center are equal, and the included angle of the side surfaces of the quadrangular frustum is gradually reduced, so that the focal length of the objective lens can be changed to a certain extent, and the focal length of the microchannel closer to the center is longer; due to the fact that the focal length of the micro-channel is changed, the image surface of the objective lens at the distance R is a plane rather than a spherical surface, high-resolution multi-spectral-band planar imaging of a target in a large field range is achieved, the problem that the working spectrum band of the system is limited by optical materials is solved, the inevitable large curvature of field of the traditional lobster eye structure imaging is effectively eliminated, system aberration is reduced, image surface energy uniformity is improved, the size and the weight of the system can be effectively compressed, the working capacity of the system is obviously improved, and the effect of application deployment is achieved.)

1. A lobster eye imaging system is characterized in that an objective lens (1) adopts a lobster eye structure, and each small eye of the objective lens (1) is a quadrangular frustum pyramid; a plurality of quadrangular frustums are closely arranged to form a hemispherical surface; the hemispherical surface is regarded as being formed by three-dimensional circular rings which are tightly attached to each other but have different radiuses, and the three-dimensional circular rings are formed by winding a circle by a plurality of quadrangular frustums; from the outermost circle of quadrangular frustum pyramid to the center circle of quadrangular frustum pyramid of the objective lens (1), the included angle of the side surface of the quadrangular frustum pyramid is gradually reduced, and the image surface of each circle of quadrangular frustum pyramid is the same plane.

2. The lobster eye imaging system of claim 1 further comprising a multiband detector (3) based on two-dimensional van der waals hetero PN junctions for multispectral imaging of light at said image plane.

3. The lobster eye imaging system as claimed in claim 2, further comprising an information processing and regulating system (4) and a pose adjusting mechanism (5); the information processing and regulating system (4) processes the image acquired by the detector (3), initially positions the target and sends a control signal to the posture adjusting mechanism (5); meanwhile, images acquired by the detector (3) are analyzed and identified, and target discrimination information is given;

the pose adjusting mechanism (5) is used for primarily positioning the target, adjusting the rotation direction of the objective lens (1) and the detector (3) and aligning the center of the imaging system with the target.

4. The lobster eye imaging system of claim 1, 2 or 3 wherein said inner wall surface of said rectangular pyramid is free-form.

5. A lobster eye imaging system is characterized by further comprising a relay lens group (2), wherein an objective lens (1) adopts a lobster eye structure; the center position of the objective lens (1) is a harmonic diffraction lens, and a hemispherical surface formed by closely arranging a plurality of small eyes is arranged around the harmonic diffraction lens; each small eye is a quadrangular frustum pyramid; the hemispherical surface is regarded as being formed by three-dimensional circular rings which are tightly attached to each other but have different radiuses, and the three-dimensional circular rings are formed by winding a circle by a plurality of quadrangular frustums; from a circle of quadrangular frustum on the outermost periphery of the objective lens (1) to a circle of quadrangular frustum at the center, the included angle of the side surface of the quadrangular frustum is gradually reduced, and the image surfaces of the quadrangular frustum are in the same plane;

the relay lens group (2) is used for converging the light rays emitted by the harmonic diffraction lens to the image surface.

6. The lobster eye imaging system of claim 5 further comprising a multiband detector (3) based on two-dimensional van der Waals heterojunction PN for multispectral imaging of light at said image plane.

7. The lobster eye imaging system as claimed in claim 6, further comprising an information processing and regulating system (4) and a pose adjusting mechanism (5); the information processing and regulating system (4) processes the image acquired by the detector (3), initially positions the target and sends a control signal to the posture adjusting mechanism (5); meanwhile, images acquired by the detector (3) are analyzed and identified, and target discrimination information is given;

the pose adjusting mechanism (5) is used for primarily positioning the target, adjusting the rotation direction of the objective lens (1) and the detector (3) and aligning the center of the imaging system with the target.

8. The lobster eye imaging system of claim 5, 6 or 7 wherein said inner wall surface of said rectangular pyramid is free-form.

9. The lobster eye imaging system of claim 5, 6 or 7 wherein the harmonic diffractive optic has a face shape that is ordinary diffractive or harmonic diffractive.

10. The lobster eye imaging system of claim 5, 6 or 7 wherein the number of layers of the harmonic diffractive optic is a single layer diffractive surface or a plurality of layers of diffractive surfaces.

Technical Field

The invention belongs to the technical field of detection, and particularly relates to a large-field small-aberration lobster eye imaging system.

Background

In working scenes such as target warning, post-disaster search and rescue and the like, the detection field range, the channel number and the imaging resolution of the optical system are constantly required to be improved. The larger the field of view range which can be monitored and detected by the optical system is, the earlier the system can find a target, and a large amount of time is won for later defense measures or rescue work; the wider the working spectrum of the optical system, the higher the imaging resolution, the larger the obtained target information amount is, the more beneficial to the accurate classification and identification of the target is, the false alarm rate of the system is reduced, and the accuracy of the system identification is improved. However, as is known, the field range and the imaging resolution of the optical system are in a mutually contradictory relationship, the range of the working spectrum of the optical system is limited by the characteristics of the optical material, and the field range, the working spectrum and the imaging resolution are difficult to be obtained in the conventional design manner, which usually causes the problems of complex system structure, increased weight, increased cost and the like, and is not favorable for the actual production, deployment and use of the system. The traditional method realizes the design of a multi-spectrum large-field-of-view high-resolution optical system and makes the system light-weighted very difficult.

In the aspect of bionic system design, an article 'design of a super-large field-of-view zooming bionic optical system' (DOI: 10.3788/IRLA201645.0818004) adopts a technical scheme based on a fisheye lens, the largest field-of-view range is 164 degrees through the fisheye lens at the forefront end, the focal length of the system is changed by changing the shape design of the lens at the rear end, and the imaging with variable resolution in large field-of-view detection can be met.

The patent application No. 201110310911.0 entitled lobster eye infrared reconnaissance alarm adopts an infrared light wave band reconnaissance scheme based on lobster eye lenses, collects infrared target radiation energy through lobster eyes, and receives the infrared target radiation energy by an uncooled infrared spherical detector at a focal plane position. However, the system has a single working spectrum, only works in an infrared band, has no response to a visible light target, has large processing difficulty and high manufacturing cost of the spherical detector, and is difficult to popularize and use according to the domestic prior art level.

Disclosure of Invention

In view of the above, the invention aims to provide a large-field-of-view small-aberration lobster eye imaging system, which can perform detection and alarm work in a large field-of-view range, acquire multispectral information and high-resolution images of key targets in the field-of-view range, effectively improve detection accuracy, and has significant advantages and broad prospects in target alarm and post-disaster search and rescue tasks.

A lobster eye imaging system is characterized in that an objective lens (1) adopts a lobster eye structure, and each small eye of the objective lens (1) is a quadrangular frustum pyramid; a plurality of quadrangular frustums are closely arranged to form a hemispherical surface; the hemispherical surface is regarded as being formed by three-dimensional circular rings which are tightly attached to each other but have different radiuses, and the three-dimensional circular rings are formed by winding a circle by a plurality of quadrangular frustums; from the outermost circle of quadrangular frustum pyramid to the center circle of quadrangular frustum pyramid of the objective lens (1), the included angle of the side surface of the quadrangular frustum pyramid is gradually reduced, and the image surface of each circle of quadrangular frustum pyramid is the same plane.

Further, the multi-band detector (3) based on the two-dimensional van der Waals heterojunction is further included and used for performing multi-band imaging on the light rays on the image surface.

Further, the system also comprises an information processing and regulating system (4) and a pose adjusting mechanism (5); the information processing and regulating system (4) processes the image acquired by the detector (3), initially positions the target and sends a control signal to the posture adjusting mechanism (5); meanwhile, images acquired by the detector (3) are analyzed and identified, and target discrimination information is given;

the pose adjusting mechanism (5) is used for primarily positioning the target, adjusting the rotation direction of the objective lens (1) and the detector (3) and aligning the center of the imaging system with the target.

Preferably, the inner wall surface of the quadrangular frustum pyramid is a free-form surface.

A lobster eye imaging system is characterized in that an objective lens (1) adopts a lobster eye structure and further comprises a relay lens group (2); the center position of the objective lens (1) is a harmonic diffraction lens, and a hemispherical surface formed by closely arranging a plurality of small eyes is arranged around the harmonic diffraction lens; each small eye is a quadrangular frustum pyramid; the hemispherical surface is regarded as being formed by three-dimensional circular rings which are tightly attached to each other but have different radiuses, and the three-dimensional circular rings are formed by winding a circle by a plurality of quadrangular frustums; from a circle of quadrangular frustum on the outermost periphery of the objective lens (1) to a circle of quadrangular frustum at the center, the included angle of the side surface of the quadrangular frustum is gradually reduced, and the image surfaces of the quadrangular frustum are in the same plane;

the relay lens group (2) is used for converging the light rays emitted by the harmonic diffraction lens to the image surface.

Further, the multi-band detector (3) based on the two-dimensional van der Waals heterojunction is further included and used for performing multi-band imaging on the light rays on the image surface.

Further, the system also comprises an information processing and regulating system (4) and a pose adjusting mechanism (5); the information processing and regulating system (4) processes the image acquired by the detector (3), initially positions the target and sends a control signal to the posture adjusting mechanism (5); meanwhile, images acquired by the detector (3) are analyzed and identified, and target discrimination information is given;

the pose adjusting mechanism (5) is used for primarily positioning the target, adjusting the rotation direction of the objective lens (1) and the detector (3) and aligning the center of the imaging system with the target.

Preferably, the inner wall surface of the quadrangular frustum pyramid is a free-form surface.

Preferably, the harmonic diffractive lens has a normal diffraction or harmonic diffraction surface type.

Preferably, the number of layers of the harmonic diffraction lens is a single-layer diffraction surface or a multi-layer diffraction surface.

The invention has the following beneficial effects:

according to the lobster eye imaging system with the large field of view and the small aberration, each small eye of an objective lens is a tiny quadrangular frustum pyramid, the inner wall surface of the tiny quadrangular frustum pyramid is a free-form surface, and a multispectral (visible light, short wave infrared and medium and long wave infrared) high-reflectivity film layer is plated on the inner wall surface of the tiny quadrangular frustum pyramid; the semi-spherical objective lens can be regarded as being composed of three-dimensional circular rings which are mutually attached but have different radiuses, and the three-dimensional circular rings are formed by a plurality of tiny quadrangular frustums which are wound by one circle; from the circle of quadrangular frustum at the outermost periphery of the objective lens to the circle of quadrangular frustum at the center, the side lengths of the small quadrangular frustum near the spherical center are equal, and the included angle of the side surfaces of the quadrangular frustum is gradually reduced, so that the focal length of the objective lens can be changed to a certain extent, and the focal length of the microchannel closer to the center is longer; due to the focal length change of the micro-channel, the image plane of the objective lens at the distance R is a plane rather than a spherical surface, so that high-resolution multi-spectral band (visible light, short wave infrared and medium and long wave infrared) plane imaging of a target in a large field range is realized, the problem that the working spectral band of the system is limited by optical materials is solved, the inevitable large curvature of field of the traditional lobster eye structure imaging is effectively eliminated, the system aberration is reduced, the image plane energy uniformity is improved, the size and the weight of the system can be effectively compressed, and the lobster eye structure has the effects of obviously improving the working capacity of the system and realizing application deployment;

the center position of an objective lens is replaced by a harmonic diffraction lens, the harmonic diffraction lens has one hundred percent of diffraction efficiency at the long position of a series of specific harmonics within the range of visible light and infrared bands, the objective lens is combined with a relay lens group, the focal length of a central area is further increased, as the focal length value of the center of the objective lens is far greater than the focal length value of the outermost periphery of the objective lens, the imaging resolution of the central area of an image plane is far higher than that of the peripheral area of the image plane, and high diffraction efficiency and high resolution imaging of a central view field can be realized in the visible light and infrared bands;

the whole lens group can be rotationally scanned in a three-dimensional direction by processing and extracting information of the obtained image and regulating and controlling the pose adjusting mechanism, so that a multi-angle image is captured, and a large detection view field range is achieved;

compared with the prior art, the lobster eye imaging system with the large field of view and the small aberration provided by the invention can solve the fundamental contradiction between large field of view detection and high-resolution imaging of an optical system. Through the optimization design of aspects such as system surface shape, structure, mode, make the system have a lot of beneficial effects: the large-view-field hemispherical objective structure and multi-angle scanning detection further expand the detection view field range of the system; the problem that the working spectrum band of the system is limited by optical materials is broken through, and multi-spectrum band (visible light, short wave infrared and medium and long wave infrared) imaging is realized; the large field curvature of the traditional lobster eye structure is eliminated, the aberration of a lobster eye imaging system is reduced, and the uniformity of the image plane illumination is improved; use novel lightweight structure, compression system size weight improves system portability and mobility, does benefit to practical application and deploys.

Drawings

Fig. 1(a) is a front view of the objective lens, and fig. 1(b) is a cross-sectional view of the objective lens.

Fig. 2 is an optical system and an optical path diagram according to an embodiment of the present invention.

The system comprises an objective lens 1, a relay lens 2, a detector 3, an information processing and regulating system 4 and a pose adjusting mechanism 5.

Fig. 3 is a schematic diagram of the change of the angle of the small eye of the objective lens.

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

Example 1:

a large field-of-view, small aberration lobster eye imaging system, as shown in figure 2, comprising: the system comprises an objective lens 1, a detector 3, an information processing and regulating system 4 and a pose adjusting mechanism 5.

The objective lens 1 of the target detection system of the invention adopts a lobster eye structure, as shown in fig. 1(a), each small eye of the objective lens 1 is a tiny quadrangular frustum pyramid; a plurality of tiny quadrangular frustums are closely arranged to form a hemispherical surface; as shown in fig. 1(b), the hemisphere may be regarded as being formed by three-dimensional circular rings with different radii and closely attached to each other, and the three-dimensional circular rings are formed by a plurality of tiny quadrangular frustums which are wound by one circle; the circular ring is a part of a three-dimensional spherical surface rather than a plane structure, and the curvature radius of the three-dimensional spherical surface is R.

The quadrangular frustum pyramid is a hollow structure with openings at the upper end surface and the lower end surface, and forms a micro-channel for light transmission; the light enters the inside of the quadrangular frustum pyramid from the opening at the outer end, is reflected by the inner wall reflecting surface, exits from the end surface at the inner end and is received by the detector 3. From the outermost circle of the four-edge table of the objective lens 1 to the center circle of the four-edge table, the included angle (the included angle between two adjacent sides) of the side surface of the four-edge table is gradually reduced, so that the focal length of the objective lens 1 has certain change, and the focal length of the micro-channel closer to the center is longer. Due to the focal length variation of the micro-channels, the image plane of the objective lens 1 at a distance R is planar rather than spherical. The inner wall surface shape of the ommatidium is a free-form surface reflecting surface with optimized design, and the imaging quality and the light energy utilization rate are improved by correcting aberration, so that imaging is clearer and the contrast is enhanced. The special design of the objective lens 1 realizes high-resolution multi-spectral band (visible light, short wave infrared and medium and long wave infrared) plane imaging of the target in a large field range.

The detector 3 is a multiband detector based on a two-dimensional van der waals heterojunction PN junction, and can image visible light and infrared light and convert target radiation light into image information.

The information processing and regulating system 4 processes the image acquired by the multi-spectral-band detector 3, initially positions the target, and sends a control signal to the orientation adjusting mechanism 5. And analyzing and identifying the image acquired by the multi-spectral-segment detector 3 and giving out target discrimination information.

The pose adjusting mechanism 5 comprises a plurality of large-stroke brakes, the brakes are connected with the imaging system, the brakes are controlled to move by applying voltages with different magnitudes according to signals of the information processing and regulating system 4, the objective lens 1 and the detector 3 are driven to rotate, the center of the system is aligned with the target, and high-resolution imaging of the target is facilitated.

The inner wall surface of the ommatidium is a free-form surface reflecting surface which is optimally designed and used for correcting aberration, improving imaging quality and improving the utilization rate of light energy.

Example 2:

a large field of view, small aberration lobster eye imaging system comprising: the bionic diffraction objective lens comprises a bionic diffraction objective lens 1, a relay lens group 2, a detector 3, an information processing and regulating system 4 and a pose adjusting mechanism 5.

On the basis of embodiment 1, the area of the central position of the objective lens is replaced by a single-layer or multi-layer harmonic diffraction lens structure to form the bionic diffraction objective lens, the harmonic diffraction surface type can enable the focal lengths of partial resonant wavelength light in visible light and infrared bands to be the same by utilizing different orders of light, and has higher diffraction efficiency, so that the axial chromatic aberration of the visible light and the infrared bands can be corrected. Then transmitted to the relay lens group 2, so that the radiation light of the target finally converges at one point on the image surface. In the area of the non-central position of the bionic diffraction objective lens 1, multi-spectral-band light is reflected on the inner wall of the ommatidium, and as the focal length value of the center of the bionic diffraction objective lens 1 is far larger than the focal length value of the outermost periphery of the bionic diffraction objective lens 1, high-diffraction-efficiency and high-resolution imaging of a central view field can be realized in visible light and infrared bands.

The diffraction surface type at the center of the bionic diffraction objective lens 1 is processed on a film material, and compared with a traditional lens under the same caliber, the bionic diffraction objective lens is lighter and thinner, the wall thickness of a peripheral micro-channel of the bionic diffraction objective lens 1 is only millimeter level, the center thickness of the bionic diffraction objective lens 1 can reach micrometer level, the weight of the bionic diffraction objective lens can be almost ignored, the processing tolerance is looser, and the realization of the lightweight and miniaturization of a system are facilitated. Compared with the traditional objective lens, the bionic diffraction objective lens has the advantages that the working spectrum band is a multispectral band (visible light band and infrared band), and the bionic diffraction objective lens has the advantages of large view field, high resolution, light weight, large caliber, low processing precision requirement, low system cost and the like.

The relay lens group 2 is composed of a plurality of lenses, and the light length of the harmonic diffraction lens passing through the central area of the objective lens 1 is compressed, so that the focal surface of the central harmonic diffraction area of the bionic diffraction objective lens 1 is coplanar with the focal surfaces of the micro-channels on the periphery.

The multispectral detector 3, the information processing and regulating system 4, and the pose adjusting mechanism 5 are the same as those in embodiment 1.

The working operation process of the target detection system comprises the following steps:

the basic mode of the system work is that the periphery of the objective lens 1 is large in visual field, multi-spectral band and high in sensitivity detection, and the center local visual field is high in resolution imaging. When a target enters the detection field range of the system, firstly, light rays radiated by the target are received by the objective lens 1, aberration is corrected through the light rays of the micro-channel structure at the periphery of the objective lens 1, the light energy utilization rate is improved, the light rays are focused and imaged on the multi-spectral-segment plane detector 3, a multi-spectral-segment image of the target is obtained, and an azimuth detection image of the target is provided. The information processing and regulating system 4 analyzes the target image in the image, calculates the target position, applies a control signal to the attitude adjusting mechanism 5, and changes the stroke of the brake to make the optical axis direction of the optical system consistent with the target predicted position. At this time, the light radiated by the target is received by the objective lens 1 again, and the light passes through the relay lens group 2 and then is imaged on the detector 3, so that a multi-spectral-band high-resolution image of the target is obtained. And identifying the target by an information processing and regulating system according to the multi-spectral-segment azimuth image and the multi-spectral-segment high-resolution image of the target.

When the target detection system is applied to a target alarm situation, the static field of view range of the alarm system is 170 degrees. Under the conventional state, the information processing and regulating system 4 applies regularly changed voltage to the pose adjusting mechanism 5, so that the stroke of a brake of the pose adjusting mechanism 5 is changed, the warning system is driven to carry out two-dimensional scanning, and the field range of the warning system can reach over 180 degrees, which is difficult to reach by the traditional lens system at present.

Once the aircraft target enters the large-field-of-view warning range of the system, light emitted by the target light source is firstly reflected on the inner wall of the peripheral small channel of the objective lens 1, is converged and modulated by the objective lens 1, is focused on a plane at the position R, and is imaged on the multi-spectral-band detector 3. As the target is multi-spectral-band imaging, the system is sensitive to both visible and infrared characteristics, and the capability of finding the target by the system is greatly improved. According to the position of the target image on the whole image, the information processing and regulating system 4 analyzes the target azimuth information to obtain target azimuth information, and the position and orientation adjusting mechanism 5 is applied with an electric signal to control the brake of the position and orientation adjusting mechanism 5 to move, so that the direction of the warning system is controlled, and the central axis of the system is approximately the same as the target azimuth. At this time, the light emitted by the target light source is converged to the relay lens group 2 by the harmonic diffraction surface at the center of the objective lens 1 again, and is transmitted to the multi-spectral-band detector 3 for imaging, so as to obtain a high-resolution multi-spectral-band image of the target. Thus, a multi-spectral lower-resolution image and a high-resolution image of the target are obtained. The information processing and regulating system analyzes the target characteristics and characteristics according to the target characteristics and characteristics, carries out target identification and judgment and gives out early warning signals or non-key target signals.

The application scenario of the system can be post-disaster search and rescue, and the buried target is detected. The system optical parameters may be different. The surface shape of the objective lens 1 can be different, including the shape, arrangement mode, harmonic diffraction surface type and layer number of the peripheral micro-channel can be different, and the objective lens can be common diffraction, harmonic diffraction, single-layer diffraction surface or multi-layer diffraction surface and the like. The material of the multi-spectral detector 3 may be different.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.