CN111327796A - Optical imaging system based on concentric sphere secondary imaging - Google Patents
Optical imaging system based on concentric sphere secondary imaging Download PDFInfo
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- CN111327796A CN111327796A CN201811544894.5A CN201811544894A CN111327796A CN 111327796 A CN111327796 A CN 111327796A CN 201811544894 A CN201811544894 A CN 201811544894A CN 111327796 A CN111327796 A CN 111327796A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/50—Constructional details
- H04N23/54—Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0055—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element
- G02B13/006—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element at least one element being a compound optical element, e.g. cemented elements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/50—Constructional details
- H04N23/55—Optical parts specially adapted for electronic image sensors; Mounting thereof
Abstract
The invention relates to the field of imaging optical system design, in particular to an optical imaging system based on concentric sphere secondary imaging, which comprises a concentric sphere objective lens and a sub-aperture camera array, wherein the sub-aperture camera array is composed of at least two sub-aperture cameras, each sub-aperture camera comprises a secondary imaging lens and an image sensor, the optical axis of each sub-aperture camera passes through the center of the concentric sphere objective lens, each image sensor is arranged on the same spherical surface, the fields of view of the adjacent sub-aperture cameras are overlapped, the field angle of the optical imaging system formed by overlapping the fields of view of all the sub-aperture cameras is larger than or equal to 120 degrees × 70 degrees, the object-side angular resolution is 50 mu rad, the focal length of the optical imaging system is larger than or equal to 37mm, the requirements of wide field of view and high resolution are met simultaneously, and different from mechanical scanning, images in the whole field angle are acquired directly, and the optical imaging system can.
Description
Technical Field
The invention relates to the field of imaging optical system design, in particular to an optical imaging system based on concentric sphere secondary imaging.
Background
Wide field of view high resolution imaging has been modern optoelectronics (EO) and redThe goal pursued by external (IR) imaging systems. The imaging system resolution requirement is estimated by the normal human visual resolution, with an instantaneous field of view per pixel of about 0.016 ° (1 angular division) at such resolution as to provide a horizontal and vertical pair O (10) of dimensions2Imaging scenes with fields of view of the order of DEG) requires O (10)8) I.e., imaging pixels on the order of billions. Image sensors on the order of 1 billion pixels, while capable of being designed and manufactured, are relatively expensive and have a low level of technical maturity. The large-scale pixel sensor can also be obtained by directly splicing mature small-pixel sensor, but the technical difficulty of splicing implementation is high, and the method is only used in the fields of astronomy, aerospace and the like at present. Even if the image sensor technology of large-scale pixels (monolithic or direct splicing) is completely mature, aberration correction and high-quality and high-resolution imaging can be realized under a large field of view by using a monolithic or spliced large-scale pixel image sensor and a single optical system, and the required optical system is designed and machined and adjusted under the condition of the prior art with considerable difficulty. On the other hand, if the method of mechanical scanning is used for wide-field high-resolution imaging, the time required for complete imaging is long, and there is a time interval between frames, so that it is effective only for static scenes. For the related applications such as large-scale continuous monitoring, large-field imaging needs to be performed within the time range of single exposure, the detailed information of a target is not lost, only a staring imaging method can be adopted, and the application range of the method for acquiring the high-resolution large field by a mechanical scanning method is limited.
The size and the resolution of a field of view have a mutual constraint relation, and one index is usually sacrificed to enable the other index to meet the use requirement, such as a fisheye lens, although the large-field-of-view staring imaging exceeding 180 degrees can be realized, the spatial resolution is correspondingly reduced, and meanwhile, serious distortion exists. However, the time interval exists between frames of the image obtained by the scanning mode, and the image can only be applied to static scenes and cannot meet the application occasions with real-time requirements, so that the existing imaging optical system for dynamic application is difficult to simultaneously meet the requirements of wide field of view and high resolution.
Disclosure of Invention
The invention aims to provide an optical imaging system based on concentric sphere secondary imaging, which is used for solving the problem that the existing imaging optical system applied dynamically is difficult to simultaneously meet the requirements of wide field of view and high resolution.
The invention provides an optical imaging system based on concentric sphere secondary imaging, which comprises a concentric sphere objective lens and a sub-aperture camera array, wherein the sub-aperture camera array is composed of at least two sub-aperture cameras, each sub-aperture camera comprises a secondary imaging lens and an image sensor, an optical axis of each sub-aperture camera passes through the center of the concentric sphere objective lens, each image sensor is arranged on the same spherical surface, the fields of view of adjacent sub-aperture cameras are overlapped, the fields of view of all the sub-aperture cameras are overlapped to form a field angle of the optical imaging system which is larger than or equal to 120 degrees × 70 degrees, an object side resolution is 50 mu rad, and the focal length of the optical imaging system is larger than or equal to 37 mm.
The optical imaging system has the advantages that by the arrangement of the structure, the image sensors are arranged on the same spherical surface, the fields of view of the adjacent sub-aperture cameras are overlapped, the field angle of the optical imaging system formed by overlapping the fields of view of all the sub-aperture cameras is larger than or equal to 120 degrees × 70 degrees, the object-side angular resolution is 50 mu rad, the requirements of wide field of view and high resolution are met, different from mechanical scanning, the image in the whole field angle is directly acquired, and the optical imaging system can be used for dynamic scenes.
Furthermore, in order to improve the resolution requirement, the total pixel number of the optical imaging system is 43200 × 25200, the F # is 3, and the working wavelength band is 480 nm-650 nm.
Further, in order to accurately realize the optical imaging system, the sub-aperture camera comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens, wherein a surface close to the concentric sphere objective lens is taken as the front surface of each lens, the front surface and the rear surface of the first lens have the curvature radius of 41.137mm and 283.812mm respectively, the thickness of the first lens is 4mm, and the caliber of the first lens is 14.4 mm; the second lens is a double-cemented lens, the curvature radii of the front surface, the middle surface and the back surface of the second lens are respectively 27.41mm, -28.97mm and 66.02mm, the thickness is 4.5mm, and the caliber is 15 mm; the third lens is a double-cemented lens, the curvature radii of the front surface, the middle surface and the back surface of the third lens are 161.316mm, 8.94mm and-18.07 mm respectively, the thickness is 2.5mm, and the caliber is 14 mm; the curvature radiuses of the front surface and the rear surface of the fourth lens are-15.887 mm and-87.523 mm respectively, the thickness of the fourth lens is 4mm, and the caliber of the fourth lens is 14 mm; the curvature radiuses of the front surface and the rear surface of the fifth lens are-490.073 mm and-19.53 mm respectively, the thickness of the fifth lens is 5mm, and the caliber of the fifth lens is 15 mm; the curvature radiuses of the front surface and the rear surface of the sixth lens are-13.32 mm and-39.915 mm respectively, the thickness of the sixth lens is 3mm, and the caliber of the sixth lens is 14 mm; the front and rear surfaces of the seventh lens have radii of curvature of 11.072mm and 7.15mm, respectively, a thickness of 7.5mm and an aperture of 14 mm.
Furthermore, in order to optimize the arrangement of the sub-aperture cameras on the spherical surface, the arrangement is regular, simple, convenient and easy, and the chord length rate and the filling rate index can meet the requirements, the concentric sphere objective lens comprises five image receiving surfaces, the sub-aperture cameras in the sub-aperture camera array are equally divided into five parts, and the sub-aperture cameras of each part respectively correspond to one image receiving surface.
Furthermore, in order to accurately realize the optical imaging system, the concentric sphere objective lens is composed of an inner spherical optical glass layer and an outer spherical optical glass layer, the inner spherical optical glass layer and the outer spherical optical glass layer form five surfaces with the same curvature center, and the five surfaces are a first surface, a second surface, a third surface, a fourth surface and a fifth surface in sequence; the curvature radius of the first surface is 50mm, the thickness is 22.49mm, and the caliber is 96 mm; the curvature radius of the second surface is 27.51mm, the thickness is 27.51mm, and the caliber is 54.2 mm; the curvature radius of the third surface is infinite, the thickness is 27.51mm, and the caliber is 54.2 mm; the radius of curvature of the fourth surface is-27.51 mm, the thickness is 22.49mm, and the caliber is 54.2 mm; the curvature radius of the fifth surface is-50 mm, the thickness is 31.6mm, and the caliber is 96 mm.
Further, in order to ensure that the sub-aperture camera is within the optimal lateral magnification interval, the focal length of the concentric sphere objective lens is between 74mm and 92.5 mm.
Further, in order to match the field of view of the sub-aperture cameras with the above-mentioned image receiving surface to achieve a better fill factor, the aperture of the first lens in each sub-aperture camera is less than or equal to 5.71 ° to the spherical central angle of the concentric spherical objective lens.
Further, in order to ensure that the view fields are overlapped to a certain extent and simultaneously reduce the number of the sub-aperture cameras, the view fields of the sub-aperture cameras are uniformly arranged on the primary image surface of the concentric sphere objective lens at equal angles.
Further, to ensure the accuracy of the sub-aperture camera, the full field of view of the single sub-aperture camera is 9.12 °, the physical cone angle boundary of the first lens in the sub-aperture camera in the field of view is 5.71 °, and the short side of the image sensor covers an angle of view of 8.726 °.
Further, in order to ensure that the requirement of the filling rate is met, the maximum included angle between adjacent sub-aperture cameras is 7.71 degrees, the minimum included angle is 6.34 degrees, the chord length rate of the optical imaging system is 0.216, and the filling rate value is 76.61 percent.
Drawings
FIG. 1 is a schematic diagram of an optical imaging system based on concentric sphere secondary imaging of the present invention;
FIG. 2 is a schematic diagram of a regular icosahedron of the present invention;
FIG. 3 is a graph of the regular triangle ABC of the regular icosahedron of the present invention as a function of the circumscribed sphere O of the regular icosahedron;
FIG. 4 is a schematic view of the field of view on the primary image plane of a concentric sphere objective of the present invention;
FIG. 5 is a schematic view of the equiangular arrangement of the sub-aperture camera fields of view on a spherical surface in accordance with the present invention;
FIG. 6 is a schematic view of an equi-angularly averaged total field of view of the sub-aperture camera field of view of the present invention within the entire triangle ABC;
FIG. 7 is a schematic view of the equiangular arrangement of the sub-aperture camera fields of view of the present invention over the entire field of view;
FIG. 8 is a schematic diagram of a first order layout of the secondary imaging of a concentric sphere objective lens of the present invention;
FIG. 9 is a schematic diagram of the maximum size of the concentric sphere objective secondary imaging optical system of the present invention;
FIG. 10 is a diagram of a single-pass design optical path of an optical system based on concentric sphere secondary imaging according to the present invention;
FIG. 11 is an optical path diagram of the optical system of the present invention based on concentric sphere secondary imaging with a reduced aperture of the first lens in a one-way design;
FIG. 12 is a graph of field curvature and relative distortion for a first lens aperture reduced sub-aperture camera of the present invention;
FIG. 13 is a schematic diagram of a three-dimensional model of a first view angle of an optical imaging system based on concentric sphere secondary imaging according to the present invention;
FIG. 14 is a schematic diagram of a three-dimensional model of a second viewing angle of the optical imaging system based on concentric sphere secondary imaging according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The invention provides an optical imaging system based on concentric sphere secondary imaging, as shown in fig. 1, the optical imaging system comprises a concentric sphere objective lens and a sub-aperture camera array, the sub-aperture camera array is composed of at least two sub-aperture cameras, each sub-aperture camera comprises a secondary imaging lens and an image sensor, an optical axis of each sub-aperture camera passes through the center of the concentric sphere objective lens, each image sensor is arranged on the same spherical surface, the fields of view of adjacent sub-aperture cameras are overlapped, the fields of view of all the sub-aperture cameras are overlapped to form a field angle of the optical imaging system which is larger than or equal to 120 degrees × 70 degrees, the object side angular resolution is 50 μ rad, the focal length of the optical imaging system is larger than or equal to 37mm, the total pixel number of the optical imaging system is 43 43200 × 25200, the F # is 3, and the working wave band is 480 nm-650.
The design field angle of the imaging optical system reaches 120 degrees × 70 degrees, the object-side angular resolution is 50 mu rad, the total pixel number of the system is 43200 × 25200 approximately 10.88 billion, in the aspect of sensor model selection, through contrast selection, the sensor selects a CMOS image sensor with the resolution of 4072 × 3046 and the pixel size of 1.85 mu m, and the focal length of the corresponding imaging optical system is not less than 37mm, as shown in Table 1.
TABLE 1
The view fields of the sub-aperture cameras in the concentric sphere secondary imaging scheme are spliced to meet the requirement of overall wide view field coverage. In order to ensure that the spliced images do not have gaps, the view fields of adjacent sub-aperture cameras need to have enough overlapping rate, so that the requirement on the view field which needs to be covered by the sub-aperture cameras is provided. On the other hand, the subaperture cameras are distributed on a spherical surface concentric with the concentric spherical objective lens, there should be no interference between the subaperture camera optical systems, and the coverage of the distributed spherical surface by the circular aperture of the subaperture cameras should have a sufficiently high filling rate. Therefore, in order to achieve the two purposes, the sub-aperture camera arrays need to be arranged on the spherical surface, and on one hand, the requirement of the view field to be covered by the secondary imaging lens is reduced while the overlapping rate of adjacent view fields is ensured to be sufficient, so that the complexity of the sub-aperture camera is simplified, and the imaging quality of the whole optical system is improved; on the other hand, after the sub-aperture cameras are arranged on the spherical surface, the high filling rate of the circular aperture to the spherical surface can ensure that the optical systems of the sub-aperture cameras do not interfere with each other, meanwhile, the light-passing aperture of the optical systems of the sub-aperture cameras can be increased as much as possible, the vignetting of the edge view field of the sub-aperture cameras is reduced, the light energy is effectively utilized, and therefore the imaging quality is improved.
The uniform distribution lattice of a regular triangle on a certain face of the regular icosahedron is used as initial distribution, the chord length rate and the filling rate are used as objective functions, and the micro-movement amount of the lattice inside the regular triangle is subjected to numerical optimization, so that the center point coordinate of the secondary imaging lens on the spherical surface is obtained. In this method, the chord length ratio obtained when the mean frequency s of the equilateral triangle is 8 is 0.1661, the filling ratio is 75.95%, the chord length ratio when the mean frequency s is 10 is 0.1671, and the filling ratio is 75.80%. Because the method needs numerical optimization, the calculated amount is large, and the coordinate position rule of the central point of the obtained secondary imaging lens on the spherical surface is complex. The regular frequency of the regular triangle of the regular icosahedron is fixed, the position of the central point of the sub-aperture camera is determined by using the idea of the regular triangle of the regular icosahedron and adopting a manual adjustment method. The position of the central point of the secondary imaging lens obtained by the method is regular and can be circulated, the method is simple and convenient, the arrangement is easy, and the chord length rate and the filling rate index can meet the requirements.
The regular icosahedron is a regular polyhedron composed of 20 equilateral triangles, and has 12 vertexes, 30 edges and 20 faces, wherein every 5 regular triangles share one vertex which is a shared vertex, as shown in fig. 2. Therefore, the concentric sphere objective lens adopted by the invention comprises five image receiving surfaces, the sub-aperture cameras in the sub-aperture camera array are equally divided into five parts, the sub-aperture cameras of each part respectively correspond to one image receiving surface, and one image receiving surface is a corresponding regular triangle.
Assuming that one vertex of the regular icosahedron is A, the regular triangle ABC is one surface of the regular icosahedron, the sphere O is an external sphere of the regular icosahedron, the A, B, C points are all on the sphere O, the sphere center O coincides with the sphere center of the concentric sphere objective lens, and the sphere coincides with the primary image surface of the concentric sphere objective lens, as shown in FIG. 3.
According to the relation between the radius of the regular icosahedron circumscribed sphere and the side length of the regular icosahedron circumscribed sphere, ∠ AOB is ∠ AOC is ∠ BOC is 63.43495 °, ∠ AOB and ∠ AOC are respectively divided into 10 equal parts, each equal part angle is 6.343495 °, 90% of the equal part angle, namely 5.71 °, is taken as the physical cone angle boundary 2 θ of the first lens of the subaperture camera in the field of view, namely 2 θ is 5.71 °, and the filling rate is calculated by 6.343495 °.
As shown in fig. 4, the boundary of the sub-aperture camera viewing field range is designed to 2 β ═ 1.6 × (2 θ) ═ 9.12 °, and the angular resolution requirement and the number of pixels of the short side of the sensor photosurface determine the viewing angle 2 δ covered by the short side of the sensor to 3046 × 50 μ rad ═ 8.726 °.
The total number of 11 sub-aperture camera fields of view are equiangularly distributed on the spherical surface along ∠ AOB and ∠ AOC, and the sensor short side direction is parallel to the AB or AC direction, as shown in FIG. 5.
The method comprises the steps of dividing ∠ BOC into 10 equal parts, equally distributing 11 view fields in total on a spherical surface, overlapping a reference surface parallel to a long side of a sensor in a sub view field with an OA axis, dividing ∠ EOF into 9 equal parts, equally distributing 10 view fields in total on the spherical surface, overlapping a reference surface parallel to a long side of the sensor in the sub view field with the OA axis, equally distributing ∠ GOH into 8 equal parts, equally distributing 9 view fields in total, overlapping a reference surface parallel to a long side of the sensor in the sub view field with the OA axis, and repeating the steps until the angles cannot be re-overlapped, as shown in FIG. 6.
The total field of view inside BPQ (i.e. triangle ABC except AC side) is set around the OA array at an angle of 360 °/5 ═ 72 °, the number of arrays is 5, and the overall field of view of Φ 120 ° is obtained, as shown in fig. 7, 276 sub-aperture cameras are shared in this layout, for 120 ° × 70 ° field of view, the sub-aperture cameras can be clipped to obtain an approximately rectangular field of view within the layout of the above-mentioned Φ 120 ° field of view, and 221 sub-aperture cameras are needed to realize 120 ° × 70 ° field of view.
In the arrangement result of the sub-aperture cameras obtained by the distribution method, the maximum included angle A between the adjacent sub-aperture cameras is measuredmaxAnd the minimum angle Amin7.71 and 6.34, respectively, a chord ratio of 0.216 for this distribution can be calculated. This distribution was found to have a fill factor value of 76.61% on a face of the icosahedron.
Due to the size limitation of the rear-end circuit board of the image sensor, the volume of the whole imaging optical system cannot be reduced without limit, and the relationship between the optical total length of the system and the transverse size of the rear-end circuit is given by the following simulation calculation.
According to the principle of concentric sphere secondary imaging, the system consists of a concentric sphere objective lens and a sub-aperture camera array, and as the system image sensor is selected to be a CMOS image sensor with the pixel size of 1.85um, under the requirement of 50urad angular resolution, the focal length f of the system is 37mm, and the transverse magnification M of the optical system of the sub-aperture camera is generally 0.4-0.5. Thus, the focal length f of the concentric sphere objective lensMf/M is between 74mm and 92.5 mm. The glass material of the concentric sphere objective lens is F2(n1,V1)/BK7(n2,V2) When combined, can give n1＝1.62,ν1＝36.7,n2＝1.52,ν264.2. The concentric sphere objective has a certain focal length, the outer sphere radius is between 43.4mm and 54.2mm under the constraint of achromatic or Desel spherical aberration, and the outer sphere radius is increased along with the increase of the focal length of the concentric sphere objective, so that the outer sphere radius R of the concentric sphere objective is increased1And its focal length fMRoughly related to the system focal length f and the transverse magnification M, R1＝0.586*fM＝0.586f/M。
As shown in fig. 8, assuming that the maximum lateral dimension of the circuit board behind the image sensor is X, and the angle of rotation of two adjacent sub-aperture cameras relative to the spherical center of the concentric objective lens is 2 α, the distance s between the image sensor (i.e. the focal plane of the optical system) and the spherical center of the concentric objective lens is minimum under the condition of ensuring no interference between the circuit boards
smin＝X/(2tanα)
Therefore, the total length L of the system is L at the minimummin＝R1+smin＝0.586f/M+X/(2tanα)。
The transverse magnification M of the optical system of the sub-aperture camera is 0.45, the rotating angle 2 α of every two cameras is 6.34 degrees, and the system focal length f is 37mm, so the minimum total length of the system corresponding to the transverse dimension X of different circuit boards is shown in the table 2, and as can be seen from the table, the total length of the system needs to be increased by about 9mm when the transverse dimension of the circuit board is increased by 1mm, so that the circuit boards can be ensured not to be interfered.
TABLE 2
| Transverse dimension/mm of circuit board | Minimum total length/mm of optical system |
| 20 | 228.8 |
| 22 | 246.9 |
| 25 | 274.0 |
| 30 | 319.1 |
| 32 | 337.2 |
| 35 | 364.3 |
Meanwhile, since the system has the limitation that the lateral dimension of the opto-mechanical system does not exceed 500mm, the maximum lateral dimension of the opto-mechanical system depends on the distance between the focal planes of the outermost sub-aperture optical systems, as shown in fig. 9.
An included angle between two outermost sub-aperture optical systems is 2 θ, then a maximum transverse dimension H is known from a geometric relationship { X/(2tan α) } 2sin θ is X sin θ/tan α, H is 500mm limited by the volume of the optical machine, 2 α is 6.34 ° and θ is 63.4 ° are obtained by simulation calculation of the arrangement of the sub-aperture cameras on the spherical surface, then the maximum transverse dimension X of the circuit board is 31mm, a space of 32mm is reserved for the circuit board in order to leave a margin, and the corresponding optical total length is about 337 mm.
According to the arrangement method of the equiangular sub-aperture cameras, the design field angle of a single sub-aperture camera is 2 β -9.12 degrees, the maximum field angle of a first lens of the sub-aperture camera to a concentric sphere lens is 2 theta-5.71 degrees, the total optical length is 337mm according to the system volume requirement and simulation calculation, the central distance between every two paths of sub-aperture camera optical systems is 32mm, meanwhile, the outer concentric sphere lens is higher due to the rise height, and in order to guarantee the optical processing to be feasible, the outer layer sphere optical glass material of the concentric sphere lens needs to be selected to be an optical glass material with a blank material with enough thickness.
The concentric sphere objective lens is designed in a double-layer mode, the zoom ratio of the optical system of the sub-aperture camera is set to be about 0.5, and the optical system is designed to obtain an optical path as shown in fig. 10. At this point, the first lens of the sub-aperture camera optical system is complete.
Because the optical systems of the sub-aperture camera are distributed on the spherical surface, the physical diameter of the first lens is limited, in order to ensure that the sub-aperture optical systems do not interfere with each other when the optical systems are distributed on the spherical surface, the aperture of the first lens is smaller than 5.71 degrees relative to the opening angle of the spherical center, meanwhile, the contrast degree in the sub-aperture field of view is ensured to be as uniform as possible, the light path diagram of the first lens after the clear aperture is reduced is shown in fig. 11, and the red dotted line in the diagram is an envelope curve of the concentric spherical objective lens with the opening angle of 5.71. After the clear aperture of the first lens is reasonably selected, the sub-aperture camera has enough space on the spherical surface, but the corresponding marginal field rays can be vignetted on the first lens, so that the MTF of the marginal field is split and reduced. Although the reduction of the clear aperture of the first lens of the sub-aperture camera causes the illumination reduction of the marginal field of view and the MTF curve splitting and image quality reduction, the field of view beyond the field angle of the first lens of the optical system of the sub-aperture camera can be imaged with higher image quality in the adjacent sub-aperture camera due to the overlapping field of view of the adjacent sub-aperture camera, so the image quality of the imaging system is not substantially reduced. At this time, the single sub-aperture camera has a full field of view of 9.12 ° with barrel distortion, and the maximum relative distortion is-1.66%, as shown in fig. 12.
Measuring the spatial angle of a central optical axis in structural design software, inputting the spatial angle into optical design software for modeling, performing simulation verification on the imaging and vignetting conditions of the sub-aperture cameras distributed on one regular triangle of the regular icosahedron, and confirming the distribution condition of electronic hardware in the space and the condition of a primary image surface. As shown in fig. 13 and 14, in the concentric sphere secondary imaging system modeled by the spatial angle of the optical axis in the construction software, a 30mm diameter circle in the focal plane has no interference in this arrangement.
Detailed parameters of the optical system obtained according to the design concept are shown in table 3, the sub-aperture camera comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens, wherein a surface close to a concentric sphere objective lens in each lens is taken as the front surface of the lens, the front surface and the rear surface of the first lens have curvature radii of 41.137mm and 283.812mm respectively, the thickness of the first lens is 4mm, the material is H-Z52A, and the caliber of the first lens is 14.4 mm; the second lens is a double-cemented lens, the curvature radii of the front surface, the middle surface and the back surface of the second lens are respectively 27.41mm, -28.97mm and 66.02mm, the thickness of the second lens is 4.5mm, the materials are respectively H-BAK8 and H-ZLAF75A, and the caliber of the second lens is 15 mm; the third lens is a double-cemented lens, the curvature radii of the front surface, the middle surface and the back surface of the third lens are 161.316mm, 8.94mm and-18.07 mm respectively, the thickness is 2.5mm, the materials are H-Z52A and H-LAF50B, and the caliber is 14 mm; the curvature radius of the front surface and the curvature radius of the rear surface of the fourth lens are-15.887 mm and-87.523 mm respectively, the thickness of the fourth lens is 4mm, the fourth lens is made of H-Z52A, and the caliber of the fourth lens is 14 mm; the curvature radiuses of the front surface and the rear surface of the fifth lens are-490.073 mm and-19.53 mm respectively, the thickness of the fifth lens is 5mm, the fifth lens is made of H-ZF88, and the caliber of the fifth lens is 15 mm; the curvature radiuses of the front surface and the rear surface of the sixth lens are-13.32 mm and-39.915 mm respectively, the thickness of the sixth lens is 3mm, the sixth lens is made of H-F4, and the caliber of the sixth lens is 14 mm; the radius of curvature of the front surface and the rear surface of the seventh lens are 11.072mm and 7.15mm respectively, the thickness is 7.5mm, the material is H-ZF88, and the caliber is 14 mm.
The materials adopted by the invention are all colorless optical glass, the material composition of the colorless optical glass is relatively complex, a single molecular formula can not indicate the real material, and the optical glass materials are generally represented by glass marks of various optical glass manufacturers. The optical glass of the invention is colorless optical glass produced in a stark light way, and the designation of the adopted brand is equivalent to the designation of the adopted material of the optical lens, which belongs to the known content in the field of optical design.
The concentric sphere objective lens consists of an inner spherical surface optical glass layer and an outer spherical surface optical glass layer, wherein the inner spherical surface optical glass layer and the outer spherical surface optical glass layer form five surfaces with the same curvature center, namely a first surface, a second surface, a third surface, a fourth surface and a fifth surface in sequence; the curvature radius of the first surface is 50mm, the thickness is 22.49mm, the material is H-F4, and the caliber is 96 mm; the curvature radius of the second surface is 27.51mm, the thickness is 27.51mm, the material is H-K9L, and the caliber is 54.2 mm; the curvature radius of the third surface is infinite, the thickness is 27.51mm, the material is H-K9L, and the caliber is 54.2 mm; the radius of curvature of the fourth surface is-27.51 mm, the thickness is 22.49mm, the material is H-F4, and the caliber is 54.2 mm; the curvature radius of the fifth surface is-50 mm, the thickness is 31.6mm, and the caliber is 96 mm.
TABLE 3
The present invention has been described in relation to particular embodiments thereof, but the invention is not limited to the described embodiments. The technical means in the above embodiments are changed, replaced, modified in a manner that will be easily imaginable to those skilled in the art, and the functions of the technical means are substantially the same as those of the corresponding technical means in the present invention, and the objectives of the invention are also substantially the same, so that the technical solution formed by fine tuning the above embodiments still falls into the protection scope of the present invention.
Claims (10)
1. An optical imaging system based on concentric sphere secondary imaging is characterized by comprising a concentric sphere objective lens and a sub-aperture camera array, wherein the sub-aperture camera array is composed of at least two sub-aperture cameras, each sub-aperture camera comprises a secondary imaging lens and an image sensor, the optical axis of each sub-aperture camera passes through the center of the concentric sphere objective lens, each image sensor is arranged on the same spherical surface, the fields of view of the adjacent sub-aperture cameras are overlapped, the fields of view of all the sub-aperture cameras are overlapped to form a field angle of the optical imaging system, which is larger than or equal to 120 degrees × 70 degrees, the object-side angular resolution is 50 μ rad, and the focal length of the optical imaging system is larger than or equal to 37 mm.
2. The optical imaging system based on concentric sphere secondary imaging of claim 1, wherein the total number of pixels of the optical imaging system is 43200 × 25200, F # is 3, and the operating wavelength band is 480 nm-650 nm.
3. The optical imaging system based on concentric sphere secondary imaging of claim 1, wherein the sub-aperture camera comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens, each lens has a surface close to the concentric sphere objective lens as the front surface of the lens, the front surface and the rear surface of the first lens have curvature radii of 41.137mm and 283.812mm, the thickness of 4mm and the aperture of 14.4 mm; the second lens is a double-cemented lens, the curvature radii of the front surface, the middle surface and the back surface of the second lens are respectively 27.41mm, -28.97mm and 66.02mm, the thickness is 4.5mm, and the caliber is 15 mm; the third lens is a double-cemented lens, the curvature radii of the front surface, the middle surface and the back surface of the third lens are 161.316mm, 8.94mm and-18.07 mm respectively, the thickness is 2.5mm, and the caliber is 14 mm; the curvature radiuses of the front surface and the rear surface of the fourth lens are-15.887 mm and-87.523 mm respectively, the thickness of the fourth lens is 4mm, and the caliber of the fourth lens is 14 mm; the curvature radiuses of the front surface and the rear surface of the fifth lens are-490.073 mm and-19.53 mm respectively, the thickness of the fifth lens is 5mm, and the caliber of the fifth lens is 15 mm; the curvature radiuses of the front surface and the rear surface of the sixth lens are-13.32 mm and-39.915 mm respectively, the thickness of the sixth lens is 3mm, and the caliber of the sixth lens is 14 mm; the front and rear surfaces of the seventh lens have radii of curvature of 11.072mm and 7.15mm, respectively, a thickness of 7.5mm and an aperture of 14 mm.
4. The optical imaging system based on concentric sphere secondary imaging of claim 1, wherein the concentric sphere objective lens comprises five image receiving surfaces, the sub-aperture cameras in the sub-aperture camera array are divided into five parts, and each part of the sub-aperture cameras corresponds to one image receiving surface.
5. The optical imaging system based on concentric sphere secondary imaging of claim 1, wherein the concentric sphere objective lens is composed of an inner spherical optical glass layer and an outer spherical optical glass layer, the inner spherical optical glass layer and the outer spherical optical glass layer form five surfaces with the same curvature center, namely a first surface, a second surface, a third surface, a fourth surface and a fifth surface; the curvature radius of the first surface is 50mm, the thickness is 22.49mm, and the caliber is 96 mm; the curvature radius of the second surface is 27.51mm, the thickness is 27.51mm, and the caliber is 54.2 mm; the curvature radius of the third surface is infinite, the thickness is 27.51mm, and the caliber is 54.2 mm; the radius of curvature of the fourth surface is-27.51 mm, the thickness is 22.49mm, and the caliber is 54.2 mm; the curvature radius of the fifth surface is-50 mm, the thickness is 31.6mm, and the caliber is 96 mm.
6. The optical imaging system based on concentric sphere secondary imaging according to claim 1 or 5, characterized in that the focal length of the concentric sphere objective is between 74mm and 92.5 mm.
7. The optical imaging system based on concentric sphere secondary imaging of claim 3, wherein the aperture of the first lens in each sub-aperture camera is less than or equal to 5.71 ° to the spherical opening angle of the concentric sphere objective lens.
8. The optical imaging system based on concentric sphere secondary imaging of claim 6, characterized in that the field of view of each sub-aperture camera is arranged equiangularly uniformly on the primary image plane of the concentric sphere objective.
9. The optical imaging system based on concentric sphere secondary imaging of claim 3 or 7, characterized in that the full field of view of a single sub-aperture camera is 9.12 °, the physical cone angle boundary of the first lens in the sub-aperture camera in the field of view is 5.71 °, and the short side of the image sensor covers 8.726 ° of the field angle.
10. The optical imaging system based on concentric sphere secondary imaging of claim 9, wherein the maximum included angle between adjacent subaperture cameras is 7.71 °, the minimum included angle is 6.34 °, the chord ratio of the optical imaging system is 0.216, and the filling factor value is 76.61%.
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