A multi-reflection based ultra-wide field panoramic imaging system

Abstract

The application discloses a kind of based on multiple reflection's super large field of view panoramic imaging system, including same optical axis sequentially arranged panoramic head unit's first lens PHU1 and second lens PHU2, reflector, subsequent lens group, image detector;PHU1 is located in one side of object side and includes the front reflecting surface A5 of center and the first transmission surface A1 of peripheral annular, and one side of image side includes the second transmission surface A2 of center and the rear reflecting surface A7 of peripheral annular;PHU2 is located in one side of object side as third transmission surface A3, and one side of image side includes the fourth transmission surface A6 of center and the multiplexing reflecting surface A4 of peripheral annular;A1 receives the light of front channel, A7 receives the light of rear channel;Reflector and A7, A4 constitute three times reflecting light path.The application realizes double channel fusion large field of view imaging, and compact optical path structure.

Description

Technical Field

[0001] This invention relates to the field of panoramic ring imaging lens technology, and in particular to an ultra-large field-of-view panoramic imaging system based on multiple reflections. Background Technology

[0002] The panoramic ring lens generates a ring-shaped imaging area on the image detector through a unique optical catadioptric panoramic head unit, and uses a subsequent lens group to correct aberrations, simultaneously covering a 360-degree azimuth and a wide field of view without stitching or scanning. Compared to multi-camera arrays and traditional fisheye lens solutions, the panoramic ring lens exhibits significant advantages in terms of structural compactness and real-time performance, thus possessing unique application value in scenarios such as intelligent driving, mobile robots, security monitoring, and immersive interaction. The single image detector architecture significantly reduces the overall power consumption, size, and weight of the imaging system, which is particularly crucial for miniature devices that are extremely sensitive to load.

[0003] In scenarios requiring wide field-of-view environmental perception, such as drones and autonomous driving, optical systems are required to maintain high-quality image clarity while further expanding the field of view boundaries. This presents a significant challenge to the design of ultra-wide field-of-view panoramic ring lenses. Balancing the trade-offs between wide field-of-view coverage, structural compactness, and manufacturability remains a key challenge when designing novel panoramic ring lenses for these scenarios. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes an ultra-large field-of-view panoramic imaging system based on multiple reflections. By designing a portion of the rear surface of the panoramic head unit as a reflective area and adding additional reflectors to form a coaxial three-reflector structure, an additional large field-of-view imaging channel is introduced.

[0005] The specific technical solution is as follows: A panoramic imaging system with an ultra-large field of view based on multiple reflections includes a panoramic head unit, a reflector, a subsequent lens group, and an image detector mounted on the same optical axis; arranged sequentially from the object side to the image side are the first lens PHU1 and the second lens PHU2 of the panoramic head unit, the reflector, the subsequent lens group, and the image detector. The first lens PHU1 of the panoramic head unit has a central front reflecting surface A5 and a peripheral annular first transmission surface A1 on the object side, and a central second transmission surface A2 and a peripheral annular rear reflecting surface A7 on the image side. The second lens PHU2 of the panoramic head unit has a third transmission surface A3 on the object side, and a central fourth transmission surface A6 and a peripheral annular multiplexed reflecting surface A4 on the image side. The first transmissive surface A1 is used to receive light from the front channel, and the rear reflective surface A7 is used to receive light from the rear channel. The reflector is placed behind the panoramic head unit, and its reflective surface REF, together with the rear reflective surface A7 and the multiplexed reflective surface A4, forms a three-stage reflection light path. The coating area of ​​the multiplexed reflective surface A4 will not interfere with the outgoing light from the front channel or the reflected light between the rear reflective surface A7 and the reflector REF in the rear channel.

[0006] Furthermore, the optical paths of the front and rear channels both pass through all the elements of the subsequent lens group RLG; the second transmission surface A2 and the rear reflection surface A7 are both located on the same surface of the first lens PHU1 of the panoramic head unit; the multiplexed reflection surface A4 and the fourth transmission surface A6 are both located on the second lens PHU2 of the panoramic head unit.

[0007] Furthermore, the subsequent lens group RLG simultaneously receives light from the ultra-wide field of view of both the front and rear channels and provides aberration correction for it; the subsequent lens group includes: concave lens R1, meniscus lens R2, biconcave lens R3, meniscus lens R4, concave lens R5, biconvex lens R6, meniscus lens R7, and meniscus lens R8. The focal length of the meniscus lens R2 is negative, the focal length of the meniscus lens R4 is positive, the focal length of the meniscus lens R7 is positive, and the focal length of the meniscus lens R8 is negative.

[0008] Furthermore, the biconvex lens R6 and the meniscus lens R7 are cemented together.

[0009] Furthermore, the working focal length f of the front channel f Working focal length f of the rear channel r The following relationship must be satisfied: 2.5 < f r / f f <3.5.

[0010] Furthermore, the F-number of the front channel F f F-number of the back channel r They respectively satisfy the following relationship: 4.5 < F f <5, 5<F f <5.5.

[0011] Furthermore, in order to control the lens aperture, the diameter D of the panoramic head unit is... PHU The outer diameter D of the reflector REF REF The total length TTL of the ultra-large field-of-view panoramic imaging system based on multiple reflections satisfies the following relationship: 0.48 < D PHU / TTL<0.58, 0.5<D REF / TTL<0.6.

[0012] Furthermore, the total length TTL of the front channel 前 Total length of the back channel TTL 后 The following relationship must be satisfied: .

[0013] Furthermore, the image height of the image detector is matched with the image height of the optical system, and the pixel size of the image detector is matched with the image quality of the optical system. The resolution of the image detector is 2048×1200, and the pixel size is 4μm.

[0014] Furthermore, the images formed by the dual channels on the image plane are all annular images, and there are intervals between the image heights of the annular images; the minimum image height of the front channel on the detector is h. f1 The maximum image height is h f2 The minimum image height of the rear channel on the detector is h. r1 The maximum image height is h r2 The heights of each image satisfy the following relationship: h f2 <h r1 1 < h f2 <1.1, 1.1<h r2 <2.4.

[0015] The beneficial effects of this invention are: (1) In this invention, by only adding the reflective surface REF, a coaxial three-reflection structure is designed in conjunction with the rear surface of the panoramic head unit, thereby introducing a rear channel with a large field of view; the front channel can achieve an imaging field of view of (35°~90°)×360°, and the rear channel can achieve an imaging field of view of (90°~145°)×360°. The system realizes dual-channel fusion imaging with a large field of view, and they do not interfere with each other.

[0016] (2) The coaxial three-reflection structure designed in this invention compresses and folds the optical path, realizes a compact optical path structure, and reduces the difficulty of subsequent lens group to correct aberrations, thus realizing high-definition imaging. Attached Figure Description

[0017] Figure 1 This is a structural diagram of an ultra-large field-of-view panoramic imaging system based on multiple reflections, according to an embodiment of the present invention.

[0018] Figure 2 This is a surface annotation diagram of the panoramic head unit according to an embodiment of the present invention.

[0019] Figure 3 This is a partial enlarged view of the panoramic head unit in an embodiment of the present invention.

[0020] Figure 4 This is a structural diagram of the front channel system according to an embodiment of the present invention.

[0021] Figure 5 This is a structural diagram of the rear channel system according to an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of the imaging area distribution of the front and rear channels on the image plane according to an embodiment of the present invention.

[0023] Figure 7 This is a dot plot of the front channel in the visible light band according to an embodiment of the present invention.

[0024] Figure 8 This is a dot plot of the rear channel in the visible light band according to an embodiment of the present invention.

[0025] Figure 9 This is an MTF curve of the front channel in the visible light band according to an embodiment of the present invention.

[0026] Figure 10 This is an MTF curve of the rear channel in the visible light band according to an embodiment of the present invention.

[0027] Figure 11 This is a field curvature and F-θ distortion curve of the front channel in the visible light band, according to an embodiment of the present invention.

[0028] Figure 12 This is a field curvature and F-θ distortion curve of the rear channel in the visible light band, according to an embodiment of the present invention. Detailed Implementation

[0029] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The objectives and effects of the present invention will become clearer as a result. The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] like Figures 1-2 As shown, a panoramic imaging system with an ultra-large field of view based on multiple reflections includes a panoramic head unit (PHU) mounted on the same optical axis, a reflector, a subsequent lens group, and an image detector. Arranged sequentially from the object side to the image side are the first lens PHU1 and the second lens PHU2 of the panoramic head unit PHU, the reflector REF, the subsequent lens group RLG, and the image detector.

[0031] The first lens PHU1 of the panoramic head unit includes: an annular first transmission surface A1, a second transmission surface A2, a front reflecting surface A5, and an annular rear reflecting surface A7; wherein the first transmission surface A1 and the front reflecting surface A5 are located on the object side and are on the same plane, with the front reflecting surface A5 located at the center and the first transmission surface A1 located on the periphery of the front reflecting surface A5; the second transmission surface A2 and the rear reflecting surface A7 are located on the image side and are on the same plane, with the second transmission surface A2 located at the center and the rear reflecting surface A7 located on the periphery of the second transmission surface A2. The second lens PHU2 of the panoramic head unit includes: a third transmission surface A3, a fourth transmission surface A6, and an annular multiplex reflecting surface A4; wherein the third transmission surface A3 is located on the object side and is in close contact with the second transmission surface A2; the fourth transmission surface A6 and the multiplex reflecting surface A4 are located on the image side and are on the same plane, with the fourth transmission surface A6 located at the center and the multiplex reflecting surface A4 located on the periphery of the fourth transmission surface A6. The first transmissive surface A1 is used to receive light from the front channel, the rear reflective surface A7 is used to receive light from the rear channel, and the multiplexed reflective surface A4 can reflect light from both sides of the glass and the air, respectively for the reflection of the light paths of the front and rear channels.

[0032] Furthermore, the ultra-wide field-of-view panoramic imaging provided in this embodiment has multiple reflective surfaces and shared surfaces, so it is necessary to fully avoid interference between the relative positions of the various surfaces. In particular, the reused reflective surface A4 should ensure that its coating area does not interfere with the outgoing light from the front channel, and does not interfere with the reflected light between the rear reflective surface A7 and the reflector REF in the rear channel.

[0033] Furthermore, since the front and rear channels share the first lens PHU1 of the panoramic head unit, in order to ensure the light deflection capability of the first transmission surface A1 of PHU1, and at the same time to ensure that the edge thickness of PHU1 can be processed, the material of PHU1 is selected as glass with a refractive index greater than 1.65.

[0034] The reflective surface REF is placed behind the panoramic head unit, and together with the rear reflective surface A7 and the multiplexed reflective surface A4, it forms the three-stage reflection optical path of the rear channel.

[0035] The successor lens group RLG simultaneously receives light from both the front and rear channels across an ultra-wide field of view and provides aberration correction. The successor lens group includes: a concave lens R1, a meniscus lens R2, a biconcave lens R3, a meniscus lens R4, a concave lens R5, a biconvex lens R6, a meniscus lens R7, and a meniscus lens R8. The focal length of meniscus lens R2 is negative, while that of meniscus lens R4 and R7 is positive, and that of meniscus lens R8 is negative. The biconvex lens R6 is cemented together with meniscus lens R7.

[0036] Furthermore, in order to achieve information perception at different object distances, the working focal length f of the front channel is... fWorking focal length f of the rear channel r Must satisfy: 2.5 < f r / f f <3.5. To ensure a certain amount of light intake and image quality, the F-number of the front channel is F... f It must satisfy 4.5 < F f <5, F-number of the back channel F r Satisfying 5 < F f <5.5.

[0037] Furthermore, to avoid severely uneven weight distribution in the system, it is necessary to control the lens aperture; the diameter D of the panoramic head unit is required. PHU The outer diameter D of the reflector REF REF The total length TTL of the ultra-large field-of-view panoramic imaging system based on multiple reflections satisfies the following relationship: 0.48 < D PHU / TTL<0.58, 0.5<D REF / TTL < 0.6. Total TTL length of the front channel. 前 Total length of the back channel TTL 后 The following relationship must be satisfied: .

[0038] like Figure 3 As shown, the ultra-large field-of-view panoramic imaging system based on multiple reflections provided in this embodiment includes two imaging channels. (As...) Figure 4 As shown, the light from the front channel enters the panoramic head unit PHU through the first transmission surface A1 of PHU1, and is then reflected by the multiplexing reflection surface A4 onto the front reflection surface A5. After being reflected by the front reflection surface A5, it exits the panoramic head unit through the fourth transmission surface A6, and the outgoing light is converged onto the image plane by the subsequent lens group; as shown... Figure 5 As shown, the light from the rear channel undergoes three reflections in sequence through the rear reflecting surface A7, the reflecting mirror REF, and the multiplex reflecting surface A4. The outgoing light is then converged onto the image plane by a subsequent lens group. The front channel achieves an imaging field of view of (35°~90°)×360°, and the rear channel achieves an imaging field of view of (90°~145°)×360°. The imaging bands of both the front and rear channels are in the visible light band. The image detector is located on the image plane. In this embodiment, the image detector used is a GMAX4002, which has a resolution of 2048×1200 and a pixel size of 4μm.

[0039] The images formed by the two channels on the image plane are all circular images, and there are intervals between the image heights of the circular images; specifically, such as Figure 6 As shown, the central region is the central blind zone, the outer periphery of the central blind zone is the annular front channel imaging region, the outer periphery of the front channel imaging region is the annular rear channel imaging region, and there is a gap between the front channel imaging region and the rear channel imaging region.

[0040] Furthermore, the minimum image height of the front channel on the image detector is h. f1 The maximum image height is h f2 The minimum image height of the rear channel on the image detector is h. r1 The maximum image height is h r2 The heights of each image satisfy the following relationship: h f2 <h r1 1 < h f2 <1.1, 1.1<h r2 <2.4. The image height of the image detector matches the image height of the optical system, and the pixel size of the image detector matches the image quality of the optical system.

[0041] This embodiment also provides the structural parameters of the designed ultra-large field-of-view panoramic imaging system, including radius of curvature, thickness, refractive index and Abbe number of the material, effective semi-aperture, and even-order aspheric coefficient, as shown in Tables 1, 2, and 3: Table 1. Structural parameters of the panoramic imaging system in this embodiment. Table 2. Even-order aspherical coefficients of the panoramic imaging system provided in this example. Table 3. Conicity K of some surfaces in this embodiment The thickness parameters of the panoramic head unit shown in Table 1 are the actual distances from each surface arranged sequentially from the object side to the image side to the next surface, and do not reflect the direction of light. It should be noted that in optical design software, surface thickness represents the distance of light rays from that surface to the next surface. Because the system involves multiple reflections, the thickness of some surfaces may be negative. Since multiple reflections are involved in the rear channel, the reflector REF acts as an independent reflective element in space; therefore, the thickness of the reflector REF is used to describe its distance to the multiplexed reflective surface A4.

[0042] The system performance test results of this embodiment are shown in... Figure 7-12 In the middle. Among them Figure 7 , 8 The dot plots for the front and rear channels are shown respectively. The convergence of the dot plots reflects the convergence of light rays. The smaller the spot size, the better the image quality of the optical system. Figure 9 , 10 It is the MTF curve of the front and rear channels. Its value reflects the optical system's ability to reproduce the details of an object. The higher the MTF value, the clearer the optical system reproduces the details of the object. Figure 11 , 12These are the distortion curves of the front and rear channels, representing the degree of deformation when the system images an object. The smaller the distortion value, the more accurate the shape representation of the imaging result, but distortion does not affect the image sharpness. As shown in the figure, the root mean square radius of the dot plot of the system in this embodiment is smaller than the Airy disk, and the MTF is higher than 0.3 at the Nyquist frequency (125 lp / mm), indicating that the system has good imaging quality.

[0043] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A panoramic imaging system with an ultra-large field of view based on multiple reflections, characterized in that, It includes a panoramic head unit, a reflector, a follow-up lens group, and an image detector, all mounted on the same optical axis; arranged sequentially from the object side to the image side are the first lens PHU1 and the second lens PHU2 of the panoramic head unit, the reflector, the follow-up lens group, and the image detector. The first lens PHU1 of the panoramic head unit has a central front reflecting surface A5 and a peripheral annular first transmission surface A1 on the object side, and a central second transmission surface A2 and a peripheral annular rear reflecting surface A7 on the image side. The second lens PHU2 of the panoramic head unit has a third transmission surface A3 on the object side, and a central fourth transmission surface A6 and a peripheral annular multiplexed reflecting surface A4 on the image side. The first transmissive surface A1 is used to receive light from the front channel, and the rear reflective surface A7 is used to receive light from the rear channel. The reflector is placed behind the panoramic head unit, and its reflective surface REF, together with the rear reflective surface A7 and the multiplexed reflective surface A4, forms a three-stage reflection light path. The coating area of ​​the multiplexed reflective surface A4 will not interfere with the outgoing light from the front channel or the reflected light between the rear reflective surface A7 and the reflector REF in the rear channel.

2. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, The optical paths of the front and rear channels both pass through all the components of the subsequent lens group RLG; the second transmission surface A2 and the rear reflection surface A7 are both located on the same surface of the first lens PHU1 of the panoramic head unit; the multiplexed reflection surface A4 and the fourth transmission surface A6 are both located on the second lens PHU2 of the panoramic head unit.

3. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, The subsequent lens group RLG simultaneously receives light from the front channel and the rear channel with a very large field of view and provides aberration correction function for them; the subsequent lens group includes: concave lens R1, meniscus lens R2, biconcave lens R3, meniscus lens R4, concave lens R5, biconvex lens R6, meniscus lens R7, and meniscus lens R8. The focal length of the meniscus lens R2 is negative, the focal length of the meniscus lens R4 is positive, the focal length of the meniscus lens R7 is positive, and the focal length of the meniscus lens R8 is negative.

4. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 3, characterized in that, The biconvex lens R6 and the meniscus lens R7 are cemented together.

5. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, The working focal length f of the front channel f Working focal length f of the back channel r The following relationship must be satisfied: 2.5 < f r / f f <3.

5.

6. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, The F-number of the front channel F f F-number of the back channel r They respectively satisfy the following relationship: 4.5 < F f <5, 5<F f <5.

5.

7. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, In order to control the lens aperture, the diameter D of the panoramic head unit is... PHU The outer diameter D of the reflector REF REF The total length TTL of the ultra-large field-of-view panoramic imaging system based on multiple reflections satisfies the following relationship: 0.48 < D PHU / TTL<0.58, 0.5<D REF / TTL<0.

6.

8. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, The total length TTL of the front channel 前 Total length of the back channel TTL 后 The following relationship must be satisfied: .

9. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, The image height of the image detector is matched with the image height of the optical system, and the pixel size of the image detector is matched with the image quality of the optical system. The resolution of the image detector is 2048×1200, and the pixel size is 4μm.

10. The ultra-large field-of-view panoramic imaging system based on multiple reflections according to claim 1, characterized in that, The images formed by the dual channels on the image plane are all annular images, and there are intervals between the image heights of the annular images; the minimum image height of the front channel on the detector is h. f1 The maximum image height is h f2 The minimum image height of the rear channel on the detector is h. r1 The maximum image height is h r2 The heights of each image satisfy the following relationship: h f2 <h r1 1 < h f2 <1.1, 1.1<h r2 <2.4.

Images