Large field-of-view panoramic imaging system based on multiplexed reflectors

Abstract

The application discloses a large-view-field panoramic imaging system based on multiplexing reflecting surface, which comprises a panoramic ring head unit, a subsequent lens group and an image sensor coaxially installed, wherein the head unit comprises a second lens (PAL2) with a rear reflecting surface (A3) capable of simultaneously reflecting light from the glass side and the air side to form a forward-viewing field channel and a backward-viewing field channel respectively, and the object side of the first lens (RL1) of the subsequent lens group has a central circular area (S1) and an outer ring area (S2), wherein the central circular area (S1) and the outer ring area (S2) are two even aspheric surfaces with different surface parameters, and the central circular area (S1) and the outer ring area (S2) respectively produce deflection effects on the light from the forward-viewing field channel and the backward-viewing field channel, so that the large-view-field panoramic imaging system can realize an imaging field of view range of (35°-120°) x 360°.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of panoramic optical imaging, and particularly relates to a large-view-field panoramic imaging system based on a multiplexed reflecting surface. BACKGROUND

[0002] The panoramic annular optical system needs to image objects in an ultra-large view field range to a limited size image sensor through refraction and reflection of a lens at one time, so as to obtain an annular region image of the ultra-large view field, and there is a circular blind area in the center of the image.

[0003] This ability of imaging objects in an ultra-large view field range to an image sensor at one time is due to the organic combination of the refracting surface and the reflecting surface in the head unit, but as the imaging view field range expands, the design difficulty of the system greatly increases, which brings great design problems to designers; meanwhile, the expansion of the imaging view field range may also cause the increase of the volume and mass of the system, which is not conducive to the miniaturization and light weight of the system.

[0004] Patent application with publication number CN110824673A discloses an ultra-large view field global surface panoramic annular optical system, which comprises a panoramic annular head lens, a subsequent lens group and a sensor coaxially installed, the panoramic annular head lens comprises PAL1 and PAL2 arranged in sequence from the object side to the image side, and the subsequent lens group comprises RL1, RL2, RL3, RL4, RL5, RL6 and RL7 arranged in sequence from the object side to the image side; wherein, PAL1 and RL1 are meniscus glass lenses with positive focal power, PAL2, RL3, RL4, RL5 and RL6 are double convex lenses with positive focal power, and RL2 and RL7 are double concave lenses with negative focal power; the convex surface of PAL1 faces the object side, and the concave surface faces the image side; the concave surface of RL1 faces the object side, and the convex surface faces the image side, all the lenses are composed of spherical glass, so as to realize one-time staring imaging of an ultra-large view field (55°-120°) x 360° on a limited image surface, but the optical system only uses one light channel.

[0005] Utility model patent with publication number CN217879793U discloses a panoramic annular optical system, which comprises a head unit, a subsequent lens group and a sensor arranged in sequence from the object side to the image side, the first lens comprises a front transmitting surface, a front reflecting surface and a first rear transmitting surface, the second lens comprises a multiplexed reflecting surface and a second transmitting surface; the subsequent lens group comprises four lenses, and at least one cemented lens is included in the subsequent lens group, the view field angle of the optical system can reach (40°-100°) x 360°, but the view field still cannot meet the application demand. SUMMARY

[0006] In view of the above, the purpose of the present application is to provide a large field of view panoramic imaging system based on multiplexed reflecting surface, which realizes double-channel light path imaging based on multiplexed reflecting surface to share the imaging field of view range of traditional panoramic ring structure light path, to reduce the design difficulty of large field of view panoramic ring system, and to further improve the imaging field of view.

[0007] To achieve the above-mentioned purpose of the application, the embodiment provides a large field of view panoramic imaging system based on multiplexed reflecting surface, which comprises:

[0008] The panoramic ring head unit, the subsequent lens group and the image sensor are coaxially installed, the panoramic ring head unit comprises a first lens (PAL1) and a second lens (PAL2) arranged in order from the object side to the image side; the first lens (PAL1) is a meniscus lens with positive focal power, comprising a front transmitting surface (A1), a front reflecting surface (A6) and a first transmitting surface (A2); the second lens (PAL2) is a lenticular lens with positive focal power, comprising a multiplexed reflecting surface (A3) and a second transmitting surface (A8); the subsequent lens group comprises at least two lenses arranged in order from the object side to the image side, and the multiplexed reflecting surface (A3) of the second lens (PAL2) can simultaneously reflect light rays from the glass side and the air side to form a forward field of view channel and a backward field of view channel respectively;

[0009] The object side surface of the first lens (RL1) included in the subsequent lens group has a central circular area (S1) and an outer ring area (S2), and the central circular area (S1) and the outer ring area (S2) are two even aspheric surfaces with different surface parameters, which respectively produce deflection effects on light rays from the forward field of view channel and the backward field of view channel;

[0010] The large field of view panoramic imaging system can realize an imaging field of view range of (35°-120°)×360°.

[0011] Preferably, the surface parameters of the central circular area (S1) and the outer ring area (S2) of the first lens (RL1) are designed by the following method:

[0012] The design formula of the surface parameters z(r) of the rotationally symmetric even aspheric surface is constructed as follows:

[0013]

[0014] Wherein, z is the surface height, which represents the difference between the coordinate value of any point on the surface and the coordinate value of the vertex along the optical axis, r1 is the radial coordinate at the boundary between the inner and outer aspheric surfaces, r2 is the maximum radial coordinate of the outer ring area (S2), c1 and c2 are the curvature values of the inner and outer aspheric surfaces at the vertex respectively, k1 and k2 are the conic coefficients of the inner and outer aspheric surfaces respectively, a i , b j(i,j=4,6,8,……,16) are the higher-order aspheric coefficients of the inner and outer aspheric surfaces, respectively;

[0015] At r = r1, the sagittal height of the object side of RL1 undergoes a small abrupt change, and the expression for the abrupt change is:

[0016]

[0017] Light rays from the forward field of view are refracted by the central circular region (S1) of RL1. These rays intersect the central circular region (S1) at a series of points, with the intersection point having the largest radial coordinate value denoted as Q1. Light rays from the backward field of view are refracted by the outer circular region (S2) of RL1. These rays intersect the outer circular region (S2) at a series of points, with the intersection point having the smallest radial coordinate value denoted as Q2. The radial coordinates of Q1 and Q2 are respectively... and Constrain the position of the light ray's impact point to satisfy:

[0018]

[0019] Light rays from the forward field of view are refracted by the first transmission surface (A2), reflected by the multiplexed reflection surface (A3), and reflected by the front reflection surface (A6). After being transmitted through the second transmission surface (A8), they enter the subsequent mirror group. Light rays from the backward field of view are reflected by the multiplexed reflection surface (A3) and enter the subsequent mirror group. The light rays from the forward field of view and the multiplexed reflection surface (A3) have a series of intersection points, with the smallest radial coordinate value denoted as P1. The light rays from the backward field of view and the multiplexed reflection surface (A3) also have a series of intersection points, with the smallest radial coordinate value denoted as P2. The light rays from the forward field of view and the central transmission area (A8) of the second lens PAL2 have a series of intersection points, with the largest radial coordinate value denoted as P3. To avoid obstruction of the light rays from the two channels, the radial coordinate values ​​of P1, P2, and P3 are... The following constraints must be met:

[0020]

[0021] The intersection points of light rays from the forward field of view channel with field angles of 35° and 90° with the r-axis on the image plane are denoted as P4 and P5, respectively. The intersection points of light rays from the backward field of view channel with field angles of 90° and 120° with the r-axis are denoted as P7 and P6, respectively. The images of the two channels must not overlap; that is, a certain gap must be left between points P5 and P6. It is necessary to control the radial coordinates of points P5 and P6. and The following constraints must be met:

[0022]

[0023] In the optimization, the target is that Δz(r1) approaches 0, and the constraints of (3)-(6) are added in the evaluation function to perform parameter optimization on z(r), and the surface parameters of S1 and S2 are determined after the parameter optimization.

[0024] Preferably, the object-side surface radius of curvature of the first lens (PAL1) is the image-side surface radius of curvature satisfies the following relationship:

[0025] Preferably, the object-side surface radius of curvature of the second lens (PAL2) is the image-side surface radius of curvature satisfies the following relationship:

[0026] Preferably, the total length TTL of the panoramic ring belt head unit 头部 and the total length TTL of the subsequent lens group 后继镜组 satisfies the following relationship:

[0027] Preferably, the subsequent lens group comprises seven lenses arranged in order from the object side to the image side, which are RL1, RL2, RL3, RL4, RL5, RL6 and RL7, respectively, wherein RL1, RL3, RL4, RL5 and RL7 are meniscus lenses, RL2 is a double-concave lens, and RL6 is a double-convex lens.

[0028] Preferably, the PAL1 and the PAL2 are cemented together, so that the second lens (PAL2) has the first transmission surface (A2).

[0029] Preferably, the RL2 and the RL3 are cemented together, and the RL6 and the RL7 are cemented together.

[0030] Compared with the prior art, the present application has at least the following beneficial effects:

[0031] Based on the multiplexed reflection surface (A3) of the second lens (PAL2) in the panoramic ring belt head unit, light rays from the glass side and the air side can be reflected at the same time to form a forward field of view channel and a backward field of view channel, respectively, and the object-side surface of the first lens (RL1) has a central circular region (S1) and an outer ring region (S2) to produce deflection effects on light rays from the forward field of view channel and the backward field of view channel, respectively, and the imaging field of view range of the traditional panoramic ring belt structure light path is shared, the design difficulty of the head unit of the panoramic ring belt system is reduced, and the large field of view panoramic imaging system can realize an imaging field of view range of (35°-120°)×360°. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0033] Figure 1 An optical structure diagram of a large field of view panoramic imaging system provided by the embodiment of the present application;

[0034] Figure 2 A label diagram of each surface along the optical path direction provided by the embodiment of the present application;

[0035] Figure 3 A partial enlarged view of the lens RL1 provided by the embodiment of the present application;

[0036] Figure 4 A partial enlarged view of the second lens PAL2 provided by the embodiment of the present application;

[0037] Figure 5 An image sensor imaging diagram provided by the embodiment of the present application;

[0038] Figure 6 An MTF curve diagram of a forward field of view channel of the embodiment of the present application under 486-656nm;

[0039] Figure 7 An MTF curve diagram of a backward field of view channel of the embodiment of the present application under 486-656nm;

[0040] Figure 8 A standard point column diagram of the forward field of view channel of the embodiment of the present application under 486-656nm;

[0041] Figure 9 A standard point column diagram of the backward field of view channel of the embodiment of the present application under 486-656nm;

[0042] Figure 10 A distortion curve diagram of the forward field of view channel of the embodiment of the present application under 486-656nm

[0043] Figure 11 A distortion curve diagram of the backward field of view channel of the embodiment of the present application under 486-656nm;

[0044] Figure 12 An optical path difference diagram of the forward field of view channel of the embodiment of the present application under 486-656nm;

[0045] Figure 13Optical path difference map of the backward field of view channel of the embodiment of the present application at 486-656 nm;

[0046] Figure 14 Power chromatic aberration map of the forward field of view channel of the embodiment of the present application at 486-656 nm;

[0047] Figure 15 Power chromatic aberration map of the backward field of view channel of the embodiment of the present application at 486-656 nm;

[0048] Figure 16 Relative luminance curve map of the forward field of view channel of the embodiment of the present application at 486-656 nm;

[0049] Figure 17 Relative luminance curve map of the backward field of view channel of the embodiment of the present application at 486-656 nm. DETAILED DESCRIPTION

[0050] In order to make the objects, technical solutions and advantages of the present application clearer, the present application 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 used to explain the present application and do not limit the protection scope of the present application.

[0051] The technical solutions in the embodiments of the present application will be apparently and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0052] It should be noted that in the drawings, the thickness, size and shape of the lens have been slightly exaggerated for the convenience of illustration. Specifically, the shape of the spherical surface or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or aspherical surface is not limited to the shape of the spherical surface or aspherical surface shown in the drawings. The drawings are merely examples and are not strictly drawn to scale.

[0053] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The features, principles and other aspects of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] The present application will be described in detail below in combination with the accompanying drawings and specific embodiments. The embodiments of the present application are not limited to the following embodiments.

[0055] As Figure 1 and Figure 2As shown, the embodiment provides a large field of view panoramic imaging system based on multiplexed reflecting surface, which comprises a panoramic ring head unit, a subsequent lens group and an image sensor coaxially installed. The panoramic ring head unit comprises a first lens PAL1 and a second lens PAL2 arranged in order from the object side to the image side. The first lens PAL1 is a meniscus lens with positive focal power, which comprises a front transmitting surface A1, a front reflecting surface A6 and a first transmitting surface A2. The front reflecting surface A6 is preferably located in the center region of the lens. The object side curvature radius of the first lens PAL1 is the image side curvature radius satisfies the following relationship: The second lens PAL2 is a biconvex lens with positive focal power, which comprises a multiplexed reflecting surface A3 and a second transmitting surface A8. The object side curvature radius of the second lens PAL2 is the image side curvature radius satisfies the following relationship:

[0056] The subsequent lens group comprises at least two lenses arranged in order from the object side to the image side. Preferably, as shown, Figure 1 and 2 The subsequent lens group comprises 7 lenses, which are RL1, RL2, RL3, RL4, RL5, RL6 and RL7, respectively. The lenses RL1, RL3, RL4, RL5 and RL7 are meniscus lenses, the lens RL2 is a biconcave lens, and the lens RL6 is a biconvex lens. The lens RL1 is a single lens, the front surface (i.e. the object side surface) B1 thereof is a transmitting surface, which has a center circular region S1 and an outer ring region S2 with different surface parameters, i.e. has two even aspheric surfaces, and the back surface B2 is a transmitting surface. The lens RL2 and the lens RL3 are cemented together, the front surface C1 is a transmitting surface, the back surface C3 is a transmitting surface, and the middle cemented surface C2 is a transmitting surface. The lens RL4 is a single lens, the front surface D1 is a transmitting surface, and the back surface D2 is a transmitting surface. The lens RL5 is a single lens, the front surface E1 is a transmitting surface, and the back surface E2 is a transmitting surface. The lens RL6 and the lens RL7 are cemented together, the front surface F1 is a transmitting surface, the back surface F3 is a transmitting surface, and the middle cemented surface F2 is a transmitting surface.

[0057] In the large field of view panoramic imaging system provided by the embodiment, the multiplexed reflection surface A3 of the second lens PAL2 can simultaneously reflect light from the glass side and the air side to form a forward field of view channel and a backward field of view channel respectively; the light in the two channels is deflected through the central circular area S1 and the outer ring area S2 of the lens RL1, and the deflected light is received by the image sensor after aberration correction by other lenses in the subsequent lens group. Specifically, the incident light from the forward field of view channel is refracted by the front transmission surface A1, reflected by the multiplexed reflection surface A3 to the front reflection surface A6, refracted by the second transmission surface A8 after being reflected by the front reflection surface A6, and then emitted, and the emitted light is converged on the image sensor by the subsequent lens group; the incident light from the backward field of view channel is reflected by the multiplexed reflection surface A3 and then enters the subsequent lens group, and then is corrected by the subsequent lens group and converged on the image sensor, wherein the photosensitive chip of the sensor can be Smartsens SC1330AT.

[0058] Specifically, the surface parameters of the central circular area (S1) and the outer ring area (S2) of the first lens (RL1) are designed by the following method:

[0059] In order to further control aberration and improve image quality, the object side surface of the lens RL1 is divided into a central circular area (S1) and an outer ring area (S2), and the two areas adopt different rotationally symmetric even aspherical surface coefficients, and the design formula of the surface parameters z(r) is as follows:

[0060]

[0061] Wherein, z is the surface sag, which represents the difference between the coordinate values of any point on the surface and the vertex along the optical axis, r1 is the radial coordinate at the boundary between the inner and outer aspherical surfaces, r2 is the maximum radial coordinate of the outer ring area S2, c1 and c2 are the curvature values of the inner and outer aspherical surfaces at the vertex, k1 and k2 are the conic coefficients of the inner and outer aspherical surfaces, a i , b j (i,j=4,6,8,……,16) are high-order aspherical surface coefficients of the inner and outer aspherical surfaces respectively;

[0062] At r=r1, the sag of the object side surface of RL1 has a small mutation, and the expression of the mutation is as follows:

[0063]

[0064] By dividing the object side surface of the lens RL1 into inner and outer parts, the number of design variables is greatly increased, but additional constraints are also brought. For example Figure 3As shown, the light rays from the forward field of view channel are refracted through the central circular region S1 of RL1, and the light rays and the central circular region S1 have a series of intersection points, wherein the intersection point with the maximum radial coordinate value is denoted as Q1, the light rays from the backward field of view channel are refracted through the outer annular region S2 of RL1, and the light rays and the outer annular region S2 have a series of intersection points, wherein the intersection point with the minimum radial coordinate value is denoted as Q2, the radial coordinates of Q1 and Q2 are respectively and The falling point positions of the light rays are constrained to satisfy:

[0065]

[0066] Since the reflection surface of the head unit is multiplexed to reflect the light rays, the structural parameters of the head unit simultaneously affect the imaging of the light rays of the two channels, and therefore the structural design of the head unit is very important. As shown, Figure 4 the light rays of the forward field of view channel are refracted through the first transmission surface A2, reflected by the multiplexed reflection surface A3 and the front reflection surface A6, and then transmitted by the second transmission surface A8 to enter the subsequent lens group, the light rays of the backward field of view channel are reflected by the multiplexed reflection surface A3 to enter the subsequent lens group, the light rays of the forward field of view channel and the multiplexed reflection surface A3 have a series of intersection points, wherein the intersection point with the minimum radial coordinate value is denoted as P1, the light rays of the backward field of view channel also have a series of intersection points with the multiplexed reflection surface A3, and the intersection point with the minimum radial coordinate value is denoted as P2, the light rays from the forward field of view channel and the central transmission region A8 of the second lens PAL2 have a series of intersection points, wherein the intersection point with the maximum radial coordinate value is denoted as P3, in order to avoid the obstruction of the light rays of the two channels, the radial coordinate values of P1, P2 and P3 should satisfy the following constraint conditions:

[0067]

[0068] In addition to the above constraints, the light ray falling points on the image plane should also be strictly controlled, as shown, Figure 5 the light rays of the forward field of view channel and the backward field of view channel form an inner and outer annular region on the image plane respectively. An polar coordinate system is established with the intersection point of the optical axis and the image plane as the origin O. The intersection points of the light rays from the forward field of view channel with a field of view angle of 35° and 90° and the r-axis are denoted as P4 and P5 respectively, and the intersection points of the light rays from the backward field of view channel with a field of view angle of 90° and 120° and the r-axis are denoted as P7 and P6 respectively. Since the imaging performance of the two channels is not exactly the same, and the annular image of the backward field of view channel is inverted inside and outside, the images of the two channels cannot overlap, that is, a certain interval should be left between the points P5 and P6, and the radial coordinates of the points P5 and P6 and should satisfy the following constraint conditions:

[0069]

[0070] In the optimization, the constraint conditions of equations (3)-(6) are added in the evaluation function to control the radial position of the light on the key surface, so as to ensure that the light in the forward field of view channel and the light in the backward field of view channel do not interfere with each other, and the surface parameters of S1 and S2 are optimized.

[0071] In the specific experiment, k1, a4, a6, k2, b4, b6, b 10 are not equal to 0, and the other aspheric parameters in equation (1) are 0. Table 1 shows the specific values.

[0072] Table 1

[0073]

[0074] In the embodiment, the total length TTL of the head unit is also controlled 头部 and the total length TTL of the subsequent lens group 后继镜组 satisfies the following relationship: When the total length of the head is constant, the total length of the subsequent lens group is effectively limited, and the total length of the overall optical system is compressed, which is beneficial to the miniaturization, lightness and low cost of the panoramic annular optical system, and has the characteristics of being easy to carry.

[0075] By reasonably configuring the curvature radius of the first lens PAL1 and the curvature radius of the second lens PAL2, since the imaging field of view range of the forward field of view channel is (35°-90°)×360°, and the imaging range of the backward field of view channel is (90°-120°)×360°, the combination of the two channels enables the panoramic imaging system to realize an imaging field of view range of (35°-120°)×360°, and the visible light resolution reaches 1.2 million pixels, which has the advantages of image stability, large imaging range and good image quality.

[0076] The embodiment also provides a large field of view panoramic imaging system designed by the embodiment, and specific parameters including a center thickness, a refractive index, an Abbe number, an effective half aperture, a curvature radius, a conic coefficient and an even aspheric high-order coefficient are shown in Tables 2 and 3.

[0077] Table 2

[0078] Surface No. Center Thickness Refractive Index Abbe Number Effective Half Aperture A1 23.00 1.60～1.64 55～59 32～34 A2 18.68 1.56～1.60 56～60 32～34 A3 -18.68 MIRROR 0 23～25 A4 -23.00 1.60～1.64 55～59 32～34 A5 2.26 1.60～1.64 55～59 9～11 A6 20.74 MIRROR 0 10～12 A7 18.68 1.56～1.60 56～60 9～11 A8 26.32 8～10 B1-S1 5.6046 1.60～1.65 63～67 3～5 B1-S2 5.6046 1.60～1.65 63～67 4～6 B2 12.3775 4～6 C1 6.5157 1.56～1.60 70～74 3～5 C2 2.6466 1.81～1.85 22～26 2～4 C3 10.0050 2～4 D1 4.7580 1.56～1.60 70～74 1～3 D2 0.0740 1～3 E1 3.5990 1.56～1.60 43～47 2～4 E2 1.2329 1～3 F1 8.0825 1.56～1.60 70～74 2～4 F2 5.7048 1.81～1.85 22～26 1～3 F3 4.6818 1～3 G1 - 1～2

[0079] Table 3

[0080]

[0081]

[0082] Wherein, A1 and A5 are the same surface, A2 and A4 and A7 are the same surface. But the thickness is not the same, because the thickness term in the optical design software represents the thickness value from the surface to the next surface; due to the 2 times reflection of the light path, the light will pass through the A1 surface twice, but each time it passes through the surface, the next surface it targets may be different, so the thickness of the same surface is not consistent. For example, A2 thickness is positive, because the light needs to go to A3 surface; A4 thickness is negative, because the light needs to go back, to A5 surface.

[0083] The performance test results of the large field of view panoramic imaging system shown in Table 2 and Table 3 are as follows Figures 6-17 . Among them, Figure 6 、 7 respectively are the MTF curves of the forward and backward field of view channels, and the numerical values reflect the degree of restoration of the details of the object when the optical system is imaging, and the higher the MTF value, the better the ability to restore the details of the object. Figure 8 、 9 respectively are the spot diagrams of the forward and backward field of view channels, reflecting the size of the diffraction spot formed when the optical system images a point object, and the smaller the spot diagram, the better the imaging effect of the optical system. Figure 10 、 11 respectively are the distortion curves of the forward and backward field of view channels, reflecting the degree of deformation of the image and the object, and the smaller the distortion value, the higher the similarity of the image and the object. Figure 12 、 13 respectively are the wave aberration diagrams of the forward and backward field of view channels at different field angles, which comprehensively reflect the aberration size of the optical system, and the smaller the wave aberration value, the smaller the aberration of the optical system, and the better the imaging quality. Figure 14 、 15 respectively are the magnification chromatic aberration diagrams of the forward and backward field of view channels, reflecting the difference in the vertical image height when the optical system images at different wavelengths, and the smaller the magnification chromatic aberration value, the better the consistency of the image point position when the optical system images in polychromatic light. Figure 16 、 17 respectively are the relative illumination diagrams of the forward and backward field of view channels, reflecting the energy distribution on the image plane of the optical system, and the better the consistency of the relative illumination, the more uniform the light and dark degree on the image plane of the optical system, and the more conducive to imaging.

[0084] The performance test results of Figures 6-17 comprehensive indicate that the large field of view imaging system based on multiplexing reflection surface provided by the embodiment has high imaging quality by using the forward field of view channel and the backward field of view channel.

[0085] The above detailed description of the specific embodiments of the present application has described the technical solutions and beneficial effects of the present application, and it should be understood that the above description is only the most preferred embodiment of the present application and is not intended to limit the present application. Any modifications, supplements and equivalent replacements made within the principle range of the present application shall be included in the protection range of the present application.

Claims

1. A large field of view panoramic imaging system based on multiplexed reflection surface, comprising a panoramic ring head unit, a subsequent lens group and an image sensor coaxially installed, the panoramic ring head unit comprising a first lens (PAL1) and a second lens (PAL2) arranged in order from the object side to the image side; the first lens (PAL1) is a meniscus lens with positive focal power, comprising a front transmitting surface (A1), a front reflecting surface (A6) and a first transmitting surface (A2); the second lens (PAL2) is a lenticular lens with positive focal power, comprising a multiplexed reflecting surface (A3) and a second transmitting surface (A8); the subsequent lens group comprises at least two lenses arranged in order from the object side to the image side, characterized in that, The object side radius of curvature of the first lens (PAL1) The image side radius of curvature satisfies the following relationship: The object side radius of curvature of the second lens (PAL2) The image side radius of curvature The following relationship is satisfied: The multiplexed reflection surface (A3) of the second lens (PAL2) can simultaneously reflect light rays from the glass side and the air side, respectively forming a forward field of view channel and a backward field of view channel. the object side surface of the first lens (RL1) of the subsequent lens group has a central circular area (S1) and an outer ring area (S2), the central circular area (S1) and the outer ring area (S2) are two even aspheric surfaces with different surface parameters, and respectively produce deflection effect on light rays from the forward field of view channel and the backward field of view channel; the large field of view panoramic imaging system can realize an imaging field of view range of (35°-120°)×360°.

2. The large field-of-view panoramic imaging system based on multiplexed reflecting surfaces of claim 1, wherein, the surface parameters of the central circular area (S1) and the outer ring area (S2) of the first lens (RL1) are designed by the following way: a design formula of the surface parameters z(r) of the rotationally symmetric even aspheric surface is constructed: where z is the surface sag, representing the difference between the coordinate value of an arbitrary point on the surface and the coordinate value of the vertex along the optical axis, r1 is the radial coordinate at the boundary between the inner and outer aspheric surfaces, r2 is the maximum radial coordinate of the outer annular region (S2), c1 and c2 are the curvature values of the inner and outer aspheric surfaces at the vertex, k1 and k2 are the conic coefficients of the inner and outer aspheric surfaces, a i , b j (i,j = 4, 6, 8, …, 16) are high-order aspheric coefficients of the inner and outer aspheric surfaces, respectively. at r=r1, the sag of the object side surface of the first lens (RL1) has a slight mutation, and the expression of the mutation is: The light rays from the forward field of view pass through the central circular area (S1) of the first lens (RL1) and the light rays and the central circular area (S1) have a series of intersection points, wherein the intersection point with the maximum radial coordinate value is marked as Q1, the light rays from the backward field of view pass through the outer ring area (S2) of the first lens (RL1) and the light rays and the outer ring area (S2) have a series of intersection points, wherein the intersection point with the minimum radial coordinate value is marked as Q2, the radial coordinates of Q1 and Q2 are respectively and The falling point positions of the light rays are constrained to satisfy: The light of the forward field of view channel is refracted by the first transmission surface (A2), reflected by the multiplexing reflection surface (A3) and the front reflection surface (A6), and then transmitted by the second transmission surface (A8) to enter the subsequent lens group. The light of the backward field of view channel is reflected by the multiplexing reflection surface (A3) to enter the subsequent lens group. The light of the forward field of view channel and the multiplexing reflection surface (A3) have a series of intersection points, wherein the one with the minimum radial coordinate value is denoted as P1. The light of the backward field of view channel and the multiplexing reflection surface (A3) also have a series of intersection points, wherein the one with the minimum radial coordinate value is denoted as P2. The light from the forward field of view channel and the second transmission surface (A8) of the second lens (PAL2) have a series of intersection points, wherein the one with the maximum radial coordinate value is denoted as P3. In order to avoid the obstruction of the light of the two channels, the radial coordinate values of P1, P2 and P3 should satisfy the following constraint condition: The following constraint condition should be satisfied: The intersection points of the light rays from the forward field of view channel with field of view angles of 35° and 90° and the r-axis on the image plane are denoted as P4 and P5, respectively, and the intersection points of the light rays from the backward field of view channel with field of view angles of 90° and 120° and the r-axis on the image plane are denoted as P7 and P6, respectively. The images of the two channels cannot overlap, and a certain interval must be left between points P5 and P6. The radial coordinates of points P5 and P6 need to be controlled and The following constraint conditions are met: in the optimization, the target is that Δz(r1) approaches to 0, the constraint conditions of formulas (3)-(6) are added in the evaluation function, the parameter optimization is carried out on z(r), and the surface parameters of the central circular area (S1) and the outer ring area (S2) are determined after the parameter optimization.

3. The large field-of-view panoramic imaging system based on multiplexed reflecting surfaces of claim 1, wherein, the total length TTL of the panoramic girdle head unit 头部 and the total length TTL of the subsequent lens group 后继镜组 satisfies the following relationship:

4. The multiplexed reflector-based large field-of-view panoramic imaging system of claim 1, wherein, the subsequent lens group comprises seven lenses arranged in order from the object side to the image side, which are the first lens (RL1), the second lens (RL2), the third lens (RL3), the fourth lens (RL4), the fifth lens (RL5), the sixth lens (RL6) and the seventh lens (RL7) respectively; wherein, the first lens (RL1), the third lens (RL3), the fourth lens (RL4), the fifth lens (RL5) and the seventh lens (RL7) are meniscus lenses, the second lens (RL2) is a double concave lens, and the sixth lens (RL6) is a double convex lens.

5. The multiplexed reflector-based large field-of-view panoramic imaging system of claim 1, wherein, the first lens (PAL1) and the second lens (PAL2) are cemented together, so that the second lens (PAL2) has the first transmitting surface (A2).

6. The large field-of-view panoramic imaging system based on multiplexed reflecting surfaces of claim 4, wherein, the second lens (RL2) and the third lens (RL3) are cemented together, and the sixth lens (RL6) and the seventh lens (RL7) are cemented together.

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