Design and implementation method of multi-scale imaging system with telecentric optical path in long focal length image space and system

Abstract

The present invention discloses a method and system for designing and implementing a multi-scale imaging system with a telecentric optical path in a long-focus image space, and relates to the field of optical imaging technology. After determining the field of view of a single secondary imaging system, the present invention determines the angular range of the secondary imaging system relative to the center of the primary imaging system, thereby determining the focal length of the primary imaging system of the multi-scale imaging system, the focal lengths of the components of the secondary imaging system, and the distances between the components of the secondary imaging system. Furthermore, while ensuring the overlap rate of adjacent secondary imaging systems, the present invention derives the conditions for preventing mechanical interference in the multi-scale imaging system, thereby optically designing the primary and secondary imaging systems. Through joint optimization, a multi-scale imaging system with a telecentric optical path in a long-focus image space is obtained. This method can address issues such as the small focal length of existing multi-scale imaging systems, the susceptibility to image splicing misalignment, and the unclear influence of system parameters on whether mechanical interference occurs.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a design and implementation method and system for a long-focus image-space telecentric optical path multi-scale imaging system. Background Art

[0002] Imaging aircraft targets is a prerequisite for aircraft detection, identification, and pose calculation. The optical imaging system's ability to image aircraft targets directly impacts the precision and accuracy of these detection, identification, and pose calculations. Existing aircraft imaging systems, most of which focus on visible light, lack all-day, all-weather imaging capabilities. While shortwave infrared systems can achieve all-day, all-weather measurements, their smaller detectors and lower resolutions prevent accurate pose measurement.

[0003] Currently, methods for achieving high-resolution imaging include single-camera scanning systems, multi-camera stitching systems, multi-detector stitching systems, and multi-scale imaging systems. Among them, the multi-scale imaging system is of moderate size and has a wide range of application scenarios. The multi-scale imaging system mainly uses secondary imaging to achieve high-resolution imaging. Specifically, it first collects external light and preliminarily corrects the aberration through a primary imaging system with rotational symmetry to form an intermediate image plane. Then, multiple secondary imaging systems are arranged spherically around the primary imaging system, and there is overlap between adjacent secondary imaging systems. The secondary imaging system is used to correct the remaining aberrations, and the intermediate image plane is secondary imaged on the detector. Finally, the images obtained on multiple detectors are stitched to obtain a high-resolution image.

[0004] However, the following problems are often encountered in the design and application of multi-scale imaging systems:

[0005] (1) Traditional multi-scale imaging systems have a small focal length and usually perform high-resolution imaging for large fields of view, but cannot achieve high-resolution imaging for specific targets in small fields of view.

[0006] (2) During the operation of traditional multi-scale imaging systems, the distance to the object changes, causing the position of the intermediate image plane to move. In actual use, this will cause image splicing misalignment between secondary imaging systems.

[0007] (3) The influence of the internal parameters of traditional multi-scale imaging systems on whether mechanical interference occurs is unclear, which easily increases the difficulty and complexity of optical design. Summary of the Invention

[0008] In order to solve the above problems existing in the prior art, the present invention provides a method and system for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system.

[0009] To achieve the above object, the present invention provides the following solutions:

[0010] A design and implementation method for a long-focus image-space telecentric optical path multi-scale imaging system, comprising:

[0011] Determine the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the size of the detector image plane used, and the overlap ratio of adjacent secondary imaging systems;

[0012] Determining the field of view of a single secondary imaging system using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap rate of adjacent secondary imaging systems;

[0013] Determining the angular range of the secondary imaging system relative to the center of the primary imaging system using the field of view of the single secondary imaging system;

[0014] The secondary imaging system is divided into a front group system, an aperture and a rear group system, wherein the aperture is located at the front focus of the rear group system, and an image-space telecentric optical path multi-scale imaging system model is established;

[0015] Determine, based on the angular range, expressions for the focal length of the primary imaging system of the multiscale imaging system, the focal lengths of the components of the secondary imaging system, and the distances between the components of the secondary imaging system in the image-space telecentric optical path multiscale imaging system model, and derive a condition for no mechanical interference in the multiscale imaging system while ensuring the overlap rate of adjacent secondary imaging systems;

[0016] Based on the condition that no mechanical interference occurs in the multi-scale imaging system, the focal length of the primary imaging system is determined, and the primary imaging system and the secondary imaging system are optically designed; wherein the primary imaging system is designed as a telephoto objective lens system;

[0017] The primary imaging system and the secondary imaging system for optical design are jointly optimized to obtain a long-focus image-space telecentric optical path multi-scale imaging system.

[0018] Preferably, the field of view range of a single secondary imaging system is determined using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap ratio of adjacent secondary imaging systems, specifically including:

[0019] defining a field of view of a single secondary imaging system, and determining an effective field of view of a single detector based on the defined field of view of the single secondary imaging system;

[0020] determining overlapping fields of view between adjacent secondary imaging systems based on a coincidence ratio between adjacent secondary detectors and an effective field of view of a single detector;

[0021] Determining the relationship between the field of view of a single secondary imaging system and the field of view of the entire system based on the overlapping fields of view between adjacent secondary imaging systems, the total field of view of the multi-scale imaging system, and the number of cameras in the radial direction of the total field of view;

[0022] A field of view of the single secondary imaging system is determined based on the relationship.

[0023] Preferably, the field of view of a single secondary imaging system is:

[0024]

[0025] Where 2β is the field of view of a single secondary imaging system, 2ω is the total field of view of the multi-scale imaging system, n is the number of cameras in the radial direction of the total field of view, m is the overlap ratio between adjacent secondary detectors, and γ is half the included angle of the image plane diagonal of the detector used. Both half the included angle of the image plane diagonal of the detector used and the overlap ratio between adjacent secondary detectors are determined based on the image plane size of the detector used.

[0026] Preferably, the opening angle range satisfies the following conditions:

[0027] 2θ<2βcosγ(1-m);

[0028] Where 2θ is the angular range, 2β is the field of view of a single secondary imaging system, m is the overlap ratio between adjacent secondary detectors, and γ is half the angle between the image plane diagonals of the detectors used.

[0029] Preferably, the secondary imaging system is divided into a front system, an aperture, and a rear system, wherein the aperture is located at the front focus of the rear system. An image-space telecentric optical path multi-scale imaging system model is established, specifically comprising:

[0030] Taking the intermediate image plane as the object to be imaged, the position and size of the virtual image formed by the front group system on the intermediate image plane are determined by using the paraxial imaging formula of an ideal lens in geometric optics tracing;

[0031] The virtual image formed by the front system is regarded as the object to be imaged, and the final image plane position and final image plane size obtained after the virtual image is re-imaged by the rear system are determined by using the paraxial imaging formula of the ideal lens in geometric optics tracing;

[0032] The aperture is traced into the object space to form an image of the entrance pupil. The size of the aperture in the secondary imaging system is then linked to the overall focal length and F-number of the multi-scale system through the size of the entrance pupil to obtain the overall focal length and imaging magnification of the secondary imaging system.

[0033] When the secondary imaging system is in the image-space telecentric state, the aperture of the secondary imaging system is determined by the aperture of the diaphragm, and the aperture of the secondary imaging system and the aperture of the rear group system are determined. The sizes of the aperture of the secondary imaging system and the aperture of the rear group system are:

[0034]

[0035]

[0036] Where D1 is the aperture size of the front group system in the secondary imaging system, D 光阑 is the size of the aperture, d1 is the distance between the front system and the intermediate image plane in the secondary imaging system, β 次 is the imaging magnification of the secondary imaging system, F # is the F number of the multi-scale imaging system, D2 is the aperture size of the rear group system in the secondary imaging system, f2′ is the focal length of the rear group system, 2y is the size of the intermediate image plane, and D 光阑 is the size of the aperture, l1′ is the distance between the virtual image of the front system and the front system, and d2 is the distance between the aperture and the front system.

[0037] Preferably, the condition for the multi-scale imaging system to be free of mechanical interference is that the relationship between the focal lengths of the components of the multi-scale imaging system satisfies the following formula:

[0038]

[0039] Where, F # is the F number of the multi-scale imaging system, f 主 ′ is the focal length of the front-end main imaging system, f 总 ′ is the focal length of the multi-scale imaging system, f2′ is the focal length of the rear group system, and θ is half of the angular range.

[0040] Preferably, the primary imaging system and the secondary imaging system for optical design are jointly optimized to obtain a long-focus image-space telecentric optical path multi-scale imaging system, specifically including:

[0041] Determine the overall focal length according to the imaging requirements of the multi-scale imaging system. The focal length of the primary imaging system is determined by times, and the focal length parameters under the condition of no mechanical interference are determined in turn and designed to obtain a long-focus image-space telecentric optical path multi-scale imaging system.

[0042] A system for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system, applying the above-mentioned method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system; the system comprises:

[0043] A parameter determination module is used to determine the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap rate of adjacent secondary imaging systems;

[0044] a field of view range determination module, configured to determine the field of view range of a single secondary imaging system using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap ratio of adjacent secondary imaging systems;

[0045] An angular range determining module, configured to determine an angular range of the secondary imaging system relative to the center of the primary imaging system using the field of view of the single secondary imaging system;

[0046] a system model building module, configured to divide the secondary imaging system into a front group system, an aperture, and a rear group system, wherein the aperture is located at the front focus of the rear group system, and to establish an image-space telecentric optical path multi-scale imaging system model;

[0047] a condition determination module, configured to determine, based on the angular range, expressions for the focal length of a primary imaging system of the multiscale imaging system, the focal lengths of each component of the secondary imaging system, and the distances between each component of the secondary imaging system in the image-space telecentric optical path multiscale imaging system model, and to derive a condition for preventing mechanical interference in the multiscale imaging system while ensuring an overlap ratio of adjacent secondary imaging systems;

[0048] An optical design module is used to determine the focal length of the primary imaging system based on the condition that no mechanical interference occurs in the multi-scale imaging system, and to perform optical design on the primary and secondary imaging systems; wherein the primary imaging system is designed as a telephoto objective lens system;

[0049] The imaging system optimization building module is used to jointly optimize the primary imaging system and the secondary imaging system for optical design to obtain a long-focus image-space telecentric optical path multi-scale imaging system.

[0050] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0051] The present invention utilizes the total field of view of the multi-scale imaging system, the number of cameras along the radial direction of the total field of view, the image plane size of the detector used, and the overlap ratio of adjacent secondary imaging systems to determine the field of view range of a single secondary imaging system, thereby determining the angular range of the secondary imaging system relative to the center of the primary imaging system. Based on the angular range, the focal length of the primary imaging system of the multi-scale imaging system, the focal length of each component of the secondary imaging system, and the distance between each component of the secondary imaging system in the image-space telecentric optical path multi-scale imaging system model are determined. While ensuring the overlap ratio of adjacent secondary imaging systems, the conditions for no mechanical interference in the multi-scale imaging system are derived, and the focal length of the primary imaging system is determined. This allows for optical design of the primary and secondary imaging systems, and a long-focus image-space telecentric optical path multi-scale imaging system is obtained through joint optimization. This solves the problems of existing multi-scale imaging systems, such as small focal length, easy image splicing misalignment, and unclear influence of system parameters on whether mechanical interference occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 Flowchart of the design and implementation method of the long-focus image-space telecentric optical path multi-scale imaging system provided by the present invention;

[0054] Figure 2 A schematic diagram of overlapping fields of view of adjacent secondary imaging systems provided by an embodiment of the present invention;

[0055] Figure 3 Schematic diagram of a theoretical model of a long-focus image-space telecentric optical path multi-scale imaging system provided by an embodiment of the present invention;

[0056] Figure 4 A schematic diagram of the optical path structure of a long-focus image-space telecentric optical path multi-scale imaging system provided by an embodiment of the present invention;

[0057] Figure 5 A spot diagram of a multi-scale imaging system with a telecentric optical path in the long focal length image space provided by an embodiment of the present invention;

[0058] Figure 6 An optical transfer function diagram of a long-focus image-space telecentric optical path multi-scale imaging system provided by an embodiment of the present invention;

[0059] Figure 7 Field curvature / distortion diagram of the long-focus image-space telecentric optical path multi-scale imaging system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0060] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0061] The purpose of the present invention is to provide a method and system for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system, which can solve the problems of existing multi-scale imaging systems such as small focal length, easy image stitching misalignment, and unclear influence of system parameters on whether mechanical interference occurs.

[0062] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0063] like Figure 1 As shown, the design and implementation method of the long-focus image-space telecentric optical path multi-scale imaging system of the present invention includes:

[0064] Step 100: Determine the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the size of the detector image plane used, and the overlap ratio of adjacent secondary imaging systems.

[0065] Step 101: Determine the field of view of a single secondary imaging system using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap ratio of adjacent secondary imaging systems.

[0066] In practical applications, the process of determining the field of view of a single secondary imaging system can be as follows:

[0067] (1) The field of view of a single secondary imaging system is defined as 2β. In this case, the effective field of view of a single detector is 2α = 2β cosγ, where γ represents half the diagonal angle of the image plane of the detector used.

[0068] (2) Figure 2 As shown in FIG, when the overlap rate between adjacent secondary detectors is defined as m, the size of the overlapping field of view between adjacent secondary imaging systems is 2mβcosγ.

[0069] (3) The field of view that the multi-scale imaging system needs to cover is defined as 2ω. When the number of cameras in the radial direction of the total field of view is determined to be n, the field of view of a single secondary imaging system and the field of view of the entire system should satisfy the following relationship:

[0070] 2nβcosγ-2(n-1)mβcosγ=2ω.

[0071] Based on the above relationship, the field of view of a single secondary imaging system is obtained as:

[0072]

[0073] Based on this, the field of view of a single secondary imaging system can be obtained.

[0074] Step 102: Using the field of view of a single secondary imaging system, determine the angular range of the secondary imaging system relative to the center of the primary imaging system.

[0075] In actual application, the process of determining the angular range of the secondary imaging system relative to the center of the primary imaging system can be as follows:

[0076] like Figure 2 As shown, the angular range of a single secondary imaging system relative to the center of the primary imaging system is defined as 2θ. When there is no mechanical interference between adjacent secondary imaging systems, the angular range 2θ should satisfy the following relationship:

[0077] 2θ<2βcosγ(1-m).

[0078] Therefore, when determining the field of view of the entire imaging system, the number of cameras in the radial direction of the total field of view, and the overlap rate between the fields of view of adjacent secondary imaging systems, the field of view of a single secondary imaging system can be deduced, while at the same time limiting the angular range of a single secondary imaging system relative to the center of the primary imaging system to guide subsequent optical design.

[0079] Step 103: The secondary imaging system is divided into a front system, an aperture, and a rear system. The aperture is located at the front focal point of the rear system, and a multi-scale imaging system model with an image-space telecentric optical path is established. The aperture is placed at the front focal point of the rear system to achieve an image-space telecentric optical path.

[0080] Specifically, such as Figure 3 As shown in Figure 1, the multiscale imaging system consists of a front-end primary imaging system, an intermediate image plane, a back-end secondary imaging system, and an image plane. The back-end secondary imaging system can be divided into a front system, an aperture, and a back system. The aperture is located at the front focus of the back system. After the aperture captures light into the back system, the principal ray is emitted parallel to the optical axis, achieving image telecentricity.

[0081] Based on the above description, in actual application, the process of establishing the image-space telecentric optical path multi-scale imaging system model can be as follows:

[0082] (1) Taking the intermediate image plane as the object to be imaged, the position and size (i.e., dimensions) of the virtual image formed by the front group of the secondary imaging system are calculated using the paraxial imaging formula of an ideal lens in geometric optics tracing. The formula is as follows:

[0083]

[0084] Among them, l1′ is the distance between the virtual image of the front system and the front system, f1′ is the focal length of the front system, d1 is the distance between the front system and the intermediate image plane in the secondary imaging system, 2y1′ is the size of the virtual image formed by the front system, β1 is the imaging magnification of the front system, and 2y is the size of the intermediate image plane.

[0085] (2) The virtual image formed by the front group system is regarded as the object to be imaged. The final image plane position and size obtained after the secondary imaging system rear group images it again are calculated using the paraxial imaging formula of the ideal lens in geometric optics tracing. The formula is as follows:

[0086]

[0087] Among them, the distance from the virtual image of the front system to the rear system is l2, the focal length of the rear system is f2′, the distance from the aperture to the front system is d2, β2 is the imaging magnification of the rear system, and 2y′ is the size of the image surface.

[0088] In order to ensure the telecentric imaging effect in the image space, the distance between the rear system and the aperture is fixed to the focal length f2′ of the rear system.

[0089] (3) In a multi-scale imaging system, the aperture needs to be placed in the secondary imaging system. The entrance pupil can be obtained by tracing the aperture in the object space. The size of the entrance pupil can be used to establish a relationship between the size of the aperture in the secondary imaging system and the overall focal length and F number of the multi-scale system, which satisfies the following formula:

[0090]

[0091] Among them, f 总 ′ is the focal length of the entire multi-scale imaging system, F # is the F number of the multi-scale imaging system, f 主 ′ is the focal length of the front-end main imaging system, D 入 is the entrance pupil size, D 光阑 is the size of the aperture.

[0092] This allows us to derive a formula for calculating the aperture size of the entire multi-scale imaging system under the telecentric image space condition. This ensures that the image size remains stable even if the object being imaged moves, eliminating image stitching misalignment.

[0093] (4) At this time, the overall focal length and imaging magnification of the secondary imaging system satisfy the formula:

[0094]

[0095] Among them, f 次′ is the focal length of the secondary imaging system, β 次 is the imaging magnification of the secondary imaging system.

[0096] (5) Figure 6 As shown in Figure 2, when the secondary imaging system is in the image-space telecentric state,

[0097] It can be concluded that the aperture of the rear group system is equal to the image plane size plus a certain light aperture. The aperture size of the rear group system can be calculated by similar triangles. The calculation formula is:

[0098]

[0099] Where D2 is the aperture of the rear system in the secondary imaging system.

[0100] Step 104: Determine expressions for the focal length of the primary imaging system of the multi-scale imaging system, the focal lengths of the components of the secondary imaging system, and the distances between the components of the secondary imaging system in the image-space telecentric optical path multi-scale imaging system model based on the angular range. Derivate conditions for preventing mechanical interference in the multi-scale imaging system while ensuring the overlap rate of adjacent secondary imaging systems.

[0101] In practical applications, the derivation process of the conditions for no mechanical interference in the multi-scale imaging system is as follows:

[0102] (1) In the actual design process, the main factor affecting whether mechanical interference occurs in the secondary imaging system is the aperture of the first lens. In the design process, the aperture of the front group system should be as small as possible. At this time, d2 = 0, that is, the equivalent lens of the front group system is used as the aperture of the entire multi-scale imaging system. At this time, the parameters of each component of the secondary imaging system satisfy the following formula:

[0103]

[0104] Where D1 is the aperture size of the front group system in the secondary imaging system, D 光 It is the size of the equivalent lens of the front group system.

[0105] (2) The calculated aperture of the front group system is used to calculate the condition where no mechanical interference occurs, that is, the opening angle of the first lens relative to the main imaging system is less than 2θ. The formula is as follows:

[0106]

[0107] Simplifying it, the relationship between the focal lengths of the components of the multi-scale imaging system is:

[0108]

[0109] When the corresponding parameters in the multi-scale imaging system meet this condition, no mechanical interference will occur in the entire multi-scale imaging system, which can guide the optical design and reduce the difficulty and complexity of the optical design.

[0110] Step 105: Based on the condition that the multi-scale imaging system does not cause mechanical interference, the focal length of the primary imaging system is determined, and the primary imaging system and the secondary imaging system are optically designed. The primary imaging system is designed as a telephoto objective lens system.

[0111] Step 106: Jointly optimize the primary imaging system and the secondary imaging system to obtain a long-focus image-space telecentric optical path multi-scale imaging system. For example, the two systems are jointly optimized to obtain a long-focus image-space telecentric optical path multi-scale imaging system. The details are as follows:

[0112] Determine the overall focal length according to the imaging requirements of the multi-scale imaging system. The focal length of the primary imaging system was determined by multiple times, and the focal length parameters under the condition of no mechanical interference were determined and designed accordingly. The primary imaging system was designed using the telephoto objective as the prototype. This objective is inherently suitable for long-distance and long-focal-length imaging, and can largely assume the focal length of the entire system, reducing the possibility of mechanical interference in the overall multi-scale imaging system without increasing the difficulty of optical system design.

[0113] Compared to the spherical lenses used in traditional multi-scale imaging systems, telephoto objective lenses have a smaller curvature, enabling the processing of larger aperture lenses. By combining the two, an evaluation function was set using optical design software to optimize optical performance metrics such as the RMS radius in the point diagram and the MTF value at the cutoff frequency, completing the design of a multi-scale imaging system with a telecentric optical path in the telephoto image space.

[0114] Further, based on the description of steps 100 to 106 above, when designing a multi-scale imaging system with a telephoto image-space telecentric optical path, which mainly comprises a telephoto primary imaging system and a secondary imaging system with a telephoto image-space telecentric optical path, as shown in FIG. Figures 4 to 7 As shown, the multi-scale imaging system works in the short-wave infrared band and can work all day and all weather. Its overall focal length is -200mm, F # =4.5, the field of view is 7.5°, the number of cameras used in the radial field of view is 3, the overlap rate between adjacent cameras is 16%, and the field of view of a single secondary imaging system is 3.6°. At this time, the opening angle 2θ of a single secondary imaging system to the center of the primary imaging system should be less than 2.36°, so θ = 1.17° is taken. The focal length f of the primary imaging system is determined according to the focal length relationship of each component of the multi-scale imaging system. 主′=300mm, the focal length of the rear group of the secondary imaging system should satisfy f2′<76mm. The focal length of the rear group of the actually designed secondary imaging system is f2′=56.7mm, and the focal length of the front group is f1′=31mm. It can be used as a reference to select a suitable initial structure while ensuring that there is no mechanical interference between adjacent secondary imaging systems. It can be optimized to ensure that the imaging performance of the multi-scale imaging system meets the requirements and complete the optical design.

[0115] in, Figure 4 : is a schematic diagram of the optical path structure of the long-focus image-space telecentric optical path multi-scale imaging system provided by an example of the present invention, Figure 5 This is the point diagram of the multi-scale imaging system with a telecentric optical path in the long focal length provided by the present invention. The imaging performance of the system is evaluated by its RMS radius. Figure 6 The optical transfer function diagram of the long-focus image-space telecentric optical path multi-scale imaging system provided by the embodiment of the present invention evaluates the imaging performance of the system by the MTF value at the cutoff frequency. Figure 7 This is a field curvature / distortion diagram of a multi-scale imaging system with a telecentric optical path in the telephoto image space, provided by an example of the present invention. This system's imaging performance is evaluated by assessing distortion at maximum field of view. Verification shows that the RMS radius in the spot diagram of this multi-scale imaging system with a telecentric optical path in the telephoto image space is smaller than the detector pixel size, the MTF at the cutoff frequency is greater than 0.3, and the distortion is less than 2%, meeting imaging requirements.

[0116] The long-focus image-space telecentric optical path multi-scale imaging system proposed in this invention optimizes the operating band to the short-wave infrared band, enabling the system to operate around the clock and in all weather conditions. A long-focus multi-scale imaging device was designed, capable of producing high-resolution images of the desired target. An image-space telecentric design was adopted for the secondary imaging system in traditional multi-scale imaging devices to eliminate image stitching misalignment that is common during the imaging process. Finally, an imaging model of the multi-scale imaging device was established based on the image-space telecentric mode of the secondary imaging system. Geometric optical tracing was used to determine the influence of the focal length and aperture of each system component on whether mechanical interference occurs, thereby providing parameter constraints and guiding optical design.

[0117] Based on the above description, compared with the prior art, the present invention also has the following advantages:

[0118] (1) The present invention designs the main imaging system of the traditional multi-scale imaging system into a non-rotationally symmetric telephoto objective system, which has a larger overall focal length of the system, realizes a long-focus multi-scale imaging system, and can achieve high-resolution imaging of specific targets.

[0119] (2) The secondary imaging system of the multi-scale imaging system of the present invention adopts an image-space telecentric design. When the object distance of the imaged object changes, the change in image size caused by the object being in different positions can be eliminated, thereby eliminating the image stitching misalignment that may exist between the various secondary imaging systems.

[0120] (3) Under the condition that the secondary imaging system adopts image-space telecentricity, the present invention equates the secondary imaging system to two ideal lenses and an aperture, establishes a theoretical model for it, derives the aperture size of the secondary imaging system through geometric optical tracing, and constrains the internal parameters of the system by the condition that there is no mechanical interference between the secondary imaging systems, and obtains the range of the parameters of each component to guide the design of the optical system and reduce the difficulty and complexity of the optical design.

[0121] Furthermore, the present invention provides a system for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system, facilitating the application of the aforementioned method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system. The system includes a parameter determination module, a field of view range determination module, an angular range determination module, a system model establishment module, a condition determination module, an optical design module, and an imaging system optimization and construction module.

[0122] The parameter determination module is used to determine the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap rate of adjacent secondary imaging systems.

[0123] The field of view range determination module is used to determine the field of view range of a single secondary imaging system using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap rate of adjacent secondary imaging systems.

[0124] The angular range determination module is used to determine the angular range of the secondary imaging system relative to the center of the primary imaging system by using the field of view of a single secondary imaging system.

[0125] The system model building module is used to divide the secondary imaging system into a front group system, an aperture and a rear group system. The aperture is located at the front focus of the rear group system, and a multi-scale imaging system model of the image-side telecentric optical path is established.

[0126] The condition determination module is used to determine the expressions of the focal length of the primary imaging system of the multi-scale imaging system, the focal lengths of each component in the secondary imaging system, and the distances between each component in the multi-scale imaging system model of the image-space telecentric optical path according to the angular range, and to derive the conditions for no mechanical interference in the multi-scale imaging system while ensuring the overlap rate of adjacent secondary imaging systems.

[0127] The optical design module is used to determine the focal length of the primary imaging system based on the condition that no mechanical interference occurs in the multi-scale imaging system, and to perform optical design for the primary and secondary imaging systems. The primary imaging system is designed as a telephoto objective system.

[0128] The imaging system optimization construction module is used to jointly optimize the primary imaging system and the secondary imaging system for optical design to obtain a long-focus image-space telecentric optical path multi-scale imaging system.

[0129] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0130] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A design and implementation method for a long-focus image-space telecentric optical path multi-scale imaging system, characterized in that: include: Determine the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap rate between adjacent sub-detectors; Determining the field of view of a single secondary imaging system using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detectors used, and the overlap rate between adjacent secondary detectors; Determining the angular range of the secondary imaging system relative to the center of the primary imaging system using the field of view of the single secondary imaging system; The secondary imaging system is divided into a front group system, an aperture and a rear group system, wherein the aperture is located at the front focus of the rear group system, and an image-space telecentric optical path multi-scale imaging system model is established; Determine, based on the angular range, expressions for the focal length of the primary imaging system of the multiscale imaging system, the focal lengths of the components of the secondary imaging system, and the distances between the components of the secondary imaging system in the image-space telecentric optical path multiscale imaging system model, and derive conditions for preventing mechanical interference in the multiscale imaging system while ensuring the overlap rate between adjacent secondary detectors. Based on the condition that no mechanical interference occurs in the multi-scale imaging system, the focal length of the primary imaging system is determined, and the primary imaging system and the secondary imaging system are optically designed; wherein the primary imaging system is designed as a telephoto objective lens system; The optically designed primary imaging system and secondary imaging system are jointly optimized to obtain a long-focus image-space telecentric optical path multi-scale imaging system.

2. The method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system according to claim 1, characterized in that: The field of view range of a single secondary imaging system is determined using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap rate between adjacent secondary detectors, specifically including: defining a field of view of a single secondary imaging system, and determining an effective field of view of a single detector based on the defined field of view of the single secondary imaging system; determining overlapping fields of view between adjacent secondary imaging systems based on a coincidence ratio between adjacent secondary detectors and an effective field of view of a single detector; Determining the relationship between the field of view of a single secondary imaging system and the field of view of the entire system based on the overlapping fields of view between adjacent secondary imaging systems, the total field of view of the multi-scale imaging system, and the number of cameras in the radial direction of the total field of view; A field of view of the single secondary imaging system is determined based on the relationship.

3. The method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system according to claim 2, characterized in that: The field of view of a single secondary imaging system is: Where 2β is the field of view of a single secondary imaging system, 2ω is the total field of view of the multi-scale imaging system, n is the number of cameras in the radial direction of the total field of view, m is the overlap ratio between adjacent secondary detectors, and γ is half the included angle of the image plane diagonal of the detector used. Both half the included angle of the image plane diagonal of the detector used and the overlap ratio between adjacent secondary detectors are determined based on the image plane size of the detector used.

4. The method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system according to claim 1, characterized in that: The opening angle range satisfies the following conditions: 2θ<2βcosγ(1-m); Where 2θ is the angular range, 2β is the field of view of a single secondary imaging system, m is the overlap ratio between adjacent secondary detectors, and γ is half the angle between the image plane diagonals of the detectors used.

5. The method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system according to claim 1, characterized in that: The secondary imaging system is divided into a front group system, an aperture, and a rear group system. The aperture is located at the front focus of the rear group system. An image-space telecentric optical path multi-scale imaging system model is established, specifically including: Taking the intermediate image plane as the object to be imaged, the position and size of the virtual image formed by the front group system on the intermediate image plane are determined by using the paraxial imaging formula of an ideal lens in geometric optics tracing; The virtual image formed by the front system is regarded as the object to be imaged, and the final image plane position and final image plane size obtained after the virtual image is re-imaged by the rear system are determined by using the paraxial imaging formula of the ideal lens in geometric optics tracing; The aperture is traced into the object space to form an image of the entrance pupil. The size of the aperture in the secondary imaging system is then linked to the overall focal length and F-number of the multi-scale system through the size of the entrance pupil to obtain the overall focal length and imaging magnification of the secondary imaging system. When the secondary imaging system is in the image-space telecentric state, the aperture of the secondary imaging system is determined by the aperture of the diaphragm, and the aperture of the secondary imaging system and the aperture of the rear group system are determined. The sizes of the aperture of the secondary imaging system and the aperture of the rear group system are: Where D1 is the aperture size of the front group system in the secondary imaging system, D 光阑 is the size of the aperture, d1 is the distance between the front system and the intermediate image plane in the secondary imaging system, β 次 is the imaging magnification of the secondary imaging system, F # is the F number of the multi-scale imaging system, D2 is the aperture size of the rear group system in the secondary imaging system, f2′ is the focal length of the rear group system, 2y is the size of the intermediate image plane, and D 光阑 is the size of the aperture, l1′ is the distance between the virtual image of the front system and the front system, and d2 is the distance between the aperture and the front system.

6. The method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system according to claim 1, characterized in that: The condition for a multi-scale imaging system to be free of mechanical interference is that the relationship between the focal lengths of the components of the multi-scale imaging system satisfies the following formula: Where, F # is the F number of the multi-scale imaging system, f 主 ′ is the focal length of the front-end main imaging system, f 总 ′ is the focal length of the multi-scale imaging system, f2′ is the focal length of the rear group system, and θ is half of the angular range.

7. The method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system according to claim 1, characterized in that: The optically designed primary and secondary imaging systems are jointly optimized to obtain a long-focus image-space telecentric optical path multi-scale imaging system, specifically including: Determine the overall focal length according to the imaging requirements of the multi-scale imaging system. The focal length of the primary imaging system is determined by times, and the focal length parameters under the condition of no mechanical interference are determined in turn and designed to obtain a long-focus image-space telecentric optical path multi-scale imaging system.

8. A design and implementation system for a long-focus image-space telecentric optical path multi-scale imaging system, characterized in that: The method for designing and implementing a long-focus image-space telecentric optical path multi-scale imaging system according to any one of claims 1 to 7 is applied; the system comprises: A parameter determination module is used to determine the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detector used, and the overlap rate between adjacent sub-detectors; a field of view range determination module, configured to determine the field of view range of a single secondary imaging system using the total field of view of the multi-scale imaging system, the number of cameras in the radial direction of the total field of view, the image plane size of the detectors used, and the overlap ratio between adjacent secondary detectors; An angular range determining module, configured to determine an angular range of the secondary imaging system relative to the center of the primary imaging system using the field of view of the single secondary imaging system; a system model building module, configured to divide the secondary imaging system into a front group system, an aperture, and a rear group system, wherein the aperture is located at the front focus of the rear group system, and to establish an image-space telecentric optical path multi-scale imaging system model; a condition determination module, configured to determine, based on the angular range, expressions for the focal length of a primary imaging system of the multiscale imaging system, the focal lengths of each component of the secondary imaging system, and the distances between each component of the secondary imaging system in the image-space telecentric optical path multiscale imaging system model, and to derive a condition for preventing mechanical interference in the multiscale imaging system while ensuring an overlap ratio between adjacent secondary detectors; An optical design module is used to determine the focal length of the primary imaging system based on the condition that no mechanical interference occurs in the multi-scale imaging system, and to perform optical design on the primary and secondary imaging systems; wherein the primary imaging system is designed as a telephoto objective lens system; The imaging system optimization building module is used to jointly optimize the primary imaging system and the secondary imaging system for optical design to obtain a long-focus image-space telecentric optical path multi-scale imaging system.

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