Refraction-reflection type visible light long-wave infrared dual-band imaging system

Abstract

The invention relates to the technical field of dual-band imaging, in particular to a catadioptric visible light long-wave infrared dual-band imaging system which comprises a catadioptric lens group, a spectroscope and an infrared imaging module which are arranged on the same optical axis. A first light emitting surface of the spectroscope points to the infrared imaging module; a second light-emitting surface of the spectroscope points to the visible light imaging module; the optical axis of the visible light imaging module is perpendicular to the optical axis of the catadioptric lens group. Aiming at the problem that a dual-band imaging system in the prior art needs to respectively set lens groups for a visible light band and an infrared band for aberration correction, so that the whole system is relatively complex, a refraction and reflection lens group is introduced into a front-stage lens group, and generation of chromatic aberration is avoided by using a refraction and reflection structure. And the catadioptric lens group is arranged at the common light path part in front of the spectroscope, so that the chromatic aberration on two wavebands can be effectively inhibited, correction does not need to be carried out in two imaging lens groups respectively, and the system volume is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of dual-band imaging, and in particular to a catadioptric visible light and long-wave infrared dual-band imaging system. Background Art

[0002] Traditional imaging systems can often only work within a single spectral band, or require multiple independent optical systems to cover different bands, which not only increases the complexity and volume of the system, but may also affect the stability and reliability of the system. Images in different bands have different acquisition methods, suitable weather conditions, object characteristics reflected, and anti-interference capabilities. Infrared imaging uses the radiation energy of the target. It has a certain ability to penetrate smoke, fog, snow, etc., has strong anti-interference ability, and can work at night. It is generally valued, but its imaging quality is poor. Visible light images have the advantages of rich spectral information, high resolution, and large dynamic range. The defect is that under night vision and low visibility conditions, the imaging performance is greatly limited. Visible light imaging can obtain high-resolution ground target images, but smoke, fog, and lighting have a greater impact on its imaging quality, and it is insensitive to the temperature difference between the target and the background. Infrared imaging can make up for these shortcomings of visible light imaging. Therefore, the prior art has begun to try

[0003] For example, Chinese patent CN202110703494.X discloses a dual-resolution imaging lens for visible light and near-infrared light. It is mainly composed of a front lens group, a beam splitter prism, a rear visible light lens group, a visible light image plane, a rear near-infrared light lens group and a near-infrared light image plane. The light beam is incident on the front lens group, and after being transmitted through the front lens group, it is reflected and refracted by the beam splitter prism. The transmitted light of the beam splitter prism is incident on the visible light image plane after passing through the rear visible light lens group for high-resolution visible light imaging. The reflected light of the beam splitter prism is incident on the near-infrared light image plane after passing through the rear near-infrared lens group for low-resolution near-infrared imaging. The information of the visible and near-infrared bands is fully utilized. The optimized design of the double-cemented lens and the overall structure can effectively reduce aberrations and improve imaging quality. The coaxial dual-image plane structure makes the imaging result free of parallax and easy to align and fuse.

[0004] However, in the actual implementation process, the inventors found that in this type of technical solution, since a double-cemented lens structure is introduced to correct aberrations, especially since there is a large span between the visible light band and the infrared band, it will naturally cause large chromatic aberrations. Two groups of double-cemented lens structures need to be designed for the visible light lens part and the infrared lens part to cooperate with corresponding lens groups for correction respectively. This leads to relatively complex lens groups in the lens, and the overall cost and size of the system are relatively high. Summary of the invention

[0005] In view of the above problems existing in the prior art, a catadioptric visible light and long-wave infrared dual-band imaging system is now provided.

[0006] The specific technical solutions are as follows:

[0007] A catadioptric visible light long-wave infrared dual-band imaging system, comprising a catadioptric lens group, a beam splitter, a visible light imaging module and an infrared imaging module;

[0008] The catadioptric lens group, the beam splitter and the infrared imaging module are arranged on the same optical axis;

[0009] The first light emitting surface of the beam splitter points to the infrared imaging module;

[0010] The second light emitting surface of the beam splitter points to the visible light imaging module;

[0011] The optical axis of the visible light imaging module is arranged perpendicularly to the optical axis of the catadioptric lens group.

[0012] On the other hand, the catadioptric lens group includes a first lens, a primary reflector and a secondary reflector;

[0013] The first lens is a plano-concave lens;

[0014] The reflector primary mirror is a reflector with a central opening;

[0015] The optical axes of the first lens and the reflector secondary mirror are aligned with the central opening of the reflector primary mirror.

[0016] On the other hand, the concave surface of the first lens, the primary reflector and the secondary reflector are all aspherical mirrors;

[0017] The vertex curvature of the concave surface of the first lens is 1 / 38.913;

[0018] The cone coefficient is 0;

[0019] The coefficient of the second even term is -1.3095e-05;

[0020] The coefficient of the third even term is 2.7889e-08;

[0021] The coefficient of the fourth even term is 1.9072e-10;

[0022] The curvature of the curved surface vertex of the primary mirror of the reflector is 1 / 30.264;

[0023] The cone coefficient is 0;

[0024] The coefficient of the second even term is 3.8131e-07;

[0025] The coefficient of the third even term is 1.3351e-10;

[0026] The coefficient of the fourth even term is -6.0730e-14;

[0027] The curvature of the vertex of the curved surface of the secondary mirror of the reflector is 1 / 20.733;

[0028] The cone coefficient is 0;

[0029] The coefficient of the second even term is 1.4139e-05;

[0030] The coefficient of the third even term is 2.6733e-08;

[0031] The coefficient of the fourth even term is 1.5797e-11;

[0032] The coefficient of the fifth even term is 6.5914e-13.

[0033] On the other hand, the beam splitter is a flat beam splitter;

[0034] The beam splitter is located at 15.8 mm along the optical axis of the aperture;

[0035] The spectroscope substrate material is chalcogenide glass;

[0036] The beam splitter is arranged at 45° relative to the main optical axis.

[0037] On the other hand, the material of the first lens is barium fluoride.

[0038] On the other hand, the visible light imaging module includes a first positive lens, a first negative lens, a first cover glass, and a second cover glass;

[0039] The first positive lens is a biconvex mirror;

[0040] The first negative lens is a double concave mirror;

[0041] A visible light imaging element is arranged behind the second cover glass.

[0042] On the other hand, the convex surface of the first positive lens facing the first negative lens is an aspherical surface;

[0043] The vertex curvature of the convex surface of the first positive lens facing the first negative lens is 1 / -173.247;

[0044] The cone coefficient is 0;

[0045] The coefficient of the second even term is 8.894e-05;

[0046] The coefficient of the third even term is -6.9346e-07;

[0047] The coefficient of the fourth even term is 3.9486e-09;

[0048] The coefficient of the fifth even term is -9.9823e-12.

[0049] On the other hand, the infrared imaging module includes a second positive lens and a second negative lens;

[0050] The second positive lens is a positive meniscus lens;

[0051] The second negative lens is a negative meniscus lens, and an infrared imaging element is arranged behind the second negative lens.

[0052] On the other hand, the convex surface of the second positive lens close to the beam splitter is an aspherical lens;

[0053] The curvature of the vertex of the convex surface of the second positive lens close to the beam splitter is 1 / 12.43;

[0054] The cone coefficient is 0;

[0055] The coefficient of the second even term is 4.7821e-06;

[0056] The coefficient of the third even term is -7.4629e-08;

[0057] The coefficient of the fourth even term is 1.0791e-09;

[0058] The side of the second negative lens close to the image plane is a diffraction surface;

[0059] The vertex curvature of the convex surface of the diffraction surface is 1 / 11.238;

[0060] The cone coefficient is 0;

[0061] The fourth-order aspheric coefficient is 0;

[0062] The sixth-order aspheric coefficient is 0;

[0063] The first diffraction surface coefficient is -0.0301;

[0064] The second diffraction surface coefficient is 0.0007;

[0065] The design center wavelength is 11000nm;

[0066] The refractive index of the lens is 3.1351;

[0067] The diffraction order is 1.

[0068] The above technical solution has the following advantages or beneficial effects:

[0069] In view of the problem that the dual-band imaging system of the prior art needs to set up lens groups for the visible light band and the infrared band respectively to correct the aberration, which leads to the problem that the overall system is relatively complicated, in this solution, a catadioptric lens group is introduced into the front-stage lens group, and the generation of chromatic aberration is avoided by using a catadioptric structure. And because the catadioptric lens group is set in the common optical path part before the beam splitter, the chromatic aberration in the two bands can be effectively suppressed, and there is no need to correct it separately in the two imaging lens groups, which reduces the volume of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The embodiments of the present invention will be described more fully with reference to the attached drawings, which are provided for illustration and description only and are not intended to limit the scope of the present invention.

[0071] Figure 1 is an overall schematic diagram of an embodiment of the present invention;

[0072] Figure 2 Schematic diagram of the optical path of the catadioptric lens group in an embodiment of the present invention;

[0073] Figure 3 Schematic diagram of the optical path of the visible light imaging system in an embodiment of the present invention;

[0074] Figure 4 This is a point array test diagram of a visible light imaging system in an embodiment of the present invention;

[0075] Figure 5 is a modulation transfer function curve diagram of a visible light imaging system in an embodiment of the present invention;

[0076] Figure 6 Schematic diagram of the optical path of the long-wave infrared imaging system in an embodiment of the present invention;

[0077] Figure 7 This is a point array test diagram of the long-wave infrared imaging system in an embodiment of the present invention;

[0078] Figure 8 It is a modulation transfer function curve diagram of the long-wave infrared imaging system in an embodiment of the present invention. DETAILED DESCRIPTION

[0079] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0081] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0082] The present invention comprises:

[0083] A catadioptric visible light and long wave infrared dual band imaging system, such as Figure 1 As shown, it includes a catadioptric lens group 1, a beam splitter 2, a visible light imaging module 3 and an infrared imaging module 4;

[0084] The catadioptric lens group 1, the beam splitter 2 and the infrared imaging module 3 are arranged on the same optical axis;

[0085] The first light emitting surface of the beam splitter 2 points to the infrared imaging module 4;

[0086] The second light emitting surface of the beam splitter 2 points to the visible light imaging module 3;

[0087] The optical axis of the visible light imaging module 3 is arranged perpendicular to the optical axis of the catadioptric lens group 1 .

[0088] Specifically, the dual-band imaging system in the prior art needs to set up lens groups for the visible light band and the infrared band respectively to perform aberration correction, which leads to the problem that the overall system is relatively complicated.

[0089] In this solution, a catadioptric lens group 1 is introduced into the front-stage lens group, and chromatic aberration is avoided by using a catadioptric structure.

[0090] Since the catadioptric lens group 1 is arranged in the common optical path portion in front of the beam splitter 2, the chromatic aberration in the two bands can be effectively suppressed, and there is no need to correct it separately in the visible light imaging module 3 and the infrared imaging module 4, thereby reducing the system volume.

[0091] During the implementation process, the catadioptric lens group is a lens group whose main structure is realized based on the Calingsee principle and cooperates with other lenses. Its main function is to receive the light in the visible light band and the long-wave infrared light in the infrared band emitted by the target object.

[0092] Among them, the visible light band refers to the light in the 0.4-0.8μm band, and the infrared band refers to the long-wave infrared light in the 8-14μm band.

[0093] The beam splitter 2 is a lens structure for visible light and long-wave infrared light, which can separate visible light and long-wave infrared light of two different wavelength bands through a specific optical structure or coating, so that the light is emitted from the first light-emitting surface and the second light-emitting surface respectively.

[0094] In one embodiment, the beam splitter 2 is a flat beam splitter;

[0095] The optical axis of the catadioptric lens group 1 is used as the main optical axis, and the beam splitter 2 is arranged at an angle of 45 degrees relative to the main optical axis.

[0096] The front surface of the beam splitter 2 is coated with a beam splitter film system that reflects the visible light band and transmits the long-wave infrared band.

[0097] The front surface of the beam splitter 2 serves as the first light emitting surface, and the rear surface of the beam splitter 2 serves as the second light emitting surface.

[0098] When the light is irradiated to the beam splitter 2 , the visible light component is reflected by the coating and emitted along the first light emitting surface, while the long-wave infrared light passes through the beam splitter 2 and emits along the second light emitting surface.

[0099] The optical axis of the visible light imaging module 3 is arranged perpendicularly to the main optical axis, receives the visible light reflected by the beam splitter 2, and projects the visible light onto an image imaging element, such as a CMOS, for imaging after simple processing through a lens.

[0100] The infrared imaging module 4 receives the long-wave infrared light projected by the spectroscope 2 and projects it onto an infrared imaging element, such as an infrared focal plane detector, for imaging after simple processing through a lens.

[0101] In one embodiment, Figure 2 As shown, the catadioptric lens group 1 includes a first lens 11, a primary reflector 12 and a secondary reflector 13;

[0102] The first lens 11 is a plano-concave lens;

[0103] The reflector primary mirror 12 is a reflector having a central opening;

[0104] The optical axes of the first lens 11 and the reflector secondary mirror 13 are aligned with the central opening of the reflector primary mirror 11 .

[0105] Specifically, in order to achieve a better chromatic aberration correction effect, in this embodiment, a catadioptric structure similar to an inverted Cassegrain structure is introduced into the catadioptric lens group 1.

[0106] That is, compared with the traditional Cassegrain structure, the large reflector with an opening is placed in front, and the small reflector located in the center is placed in the back.

[0107] The reflector main mirror 12 of this structure is a reflector with a central opening, and the side of the reflector close to the rear is a reflective surface;

[0108] The secondary reflector 13 is a reflector having a convex reflective surface, and the primary reflector 12 is located in front of the secondary reflector 13 .

[0109] When light passes through the opening of the primary mirror, it first reaches the reflecting surface of the secondary mirror 13, which is used as the aperture of the entire system.

[0110] With the convex vertex of the secondary reflector as the boundary, the circumferential light will be reflected to the reflecting surface behind the primary reflector 12, and will be reflected by the primary reflector 12 to the rear beam splitter 2. The above steps can avoid chromatic aberration.

[0111] Furthermore, in order to achieve preliminary correction of the optical path and increase the amount of light entering, a first lens 11 is introduced in the front stage of the secondary mirror of the reflector in this embodiment.

[0112] The first lens 11 is a plano-concave lens, which can achieve preliminary focusing of light and can also cover the cavity of the subsequent catadioptric structure.

[0113] In addition, since the above-mentioned input system is located in a common optical path portion, that is, it is necessary to receive visible light and long-wave infrared light at the same time.

[0114] The first lens 11 needs to receive light in the visible light band (0.4-0.8 μm) and the thermal imaging band (8-14 μm), and uses optical glass made of barium fluoride (BaF2) material, which has good transmittance to visible light and long-wave infrared light.

[0115] At the same time, the coatings on the surfaces of the primary reflector 12 and the secondary reflector 13 need to have good reflectivity for light in both the visible light band and the thermal imaging band.

[0116] In one embodiment, the beam splitter 2 is located at 15.8 mm along the optical axis of the aperture;

[0117] The beam splitter 2 is arranged at 45° relative to the main optical axis.

[0118] The secondary reflector 13 is used as an aperture of the system.

[0119] The optical systems of the visible light imaging module 3 and the infrared imaging module 4 are analyzed respectively below.

[0120] In one embodiment, Figure 3 As shown, the visible light imaging module 3 includes a first positive lens 31, a first negative lens 32, a first cover glass 33, and a second cover glass 34;

[0121] The first positive lens 31 is a biconvex mirror;

[0122] The first negative lens 32 is a biconcave mirror;

[0123] A visible light imaging element 35 is disposed behind the second cover glass 34 .

[0124] Specifically, in order to achieve effective correction of aberrations in the optical system, in this embodiment, for the visible light imaging system, a pair of a first positive lens 31 and a first negative lens 32 are added to the rear stage of the beam splitter 2 .

[0125] After correcting the optical path aberration, the light is projected into the visible light imaging element 35 through two cover glasses.

[0126] Based on the above settings, the maximum field of view angle of the overall system is 17.1°, the focal length is 16mm, the total length of the system is 58.8mm, and the entrance pupil diameter is 10.7mm.

[0127] The system parameters of the visible light imaging system are shown in Table 1:

[0128]

[0129] Table 1

[0130] To achieve the correction of aberrations, the concave surface of the first lens 11, the primary mirror 12 and the secondary mirror 13, and the convex surface of the first positive lens 31 facing the first negative lens 32 are aspherical surfaces, which can well balance the aberrations formed by the light passing through the refractive lens group.

[0131] Among them, the surface formula of the aspheric surface is:

[0132]

[0133] Where z is the arrow height;

[0134] c is the curvature at the vertex of the surface;

[0135] r is the distance between the projection of the surface point coordinates on the plane perpendicular to the optical axis and the optical axis;

[0136] k is the cone coefficient;

[0137] a1a2a3a4a5a6a7 a8 represent the coefficients corresponding to the even-order terms.

[0138] The surface parameters of multiple aspheric surfaces in the visible light system are shown in Table 2. The surface numbers on the left side of Table 2 correspond to the numbers of each surface in Table 1.

[0139]

[0140]

[0141] Table 2

[0142] The point array test diagram of the above system is as follows Figure 4 As shown, the modulation transfer function curve is as follows Figure 5 shown.

[0143] It can be seen that the modulation transfer function curve of the visible light imaging system has a central field of view of about 0.4 at 200 cycles / mm, an edge field of view greater than 0.2, and a diffuse spot radius of the imaging system less than or equal to 0.003801 mm, which enables high-quality imaging.

[0144] In one embodiment, Figure 6 As shown, the infrared imaging module 4 is located at 23 mm along the optical axis of the aperture, and has an off-axis amount of 0.6065 mm relative to the optical axis. The infrared imaging module 4 includes a second positive lens 41 and a second negative lens 42;

[0145] The second positive lens 41 is a positive meniscus lens;

[0146] The second negative lens 42 is a negative meniscus lens, and an infrared imaging element is disposed behind the second negative lens 42 .

[0147] Specifically, in order to achieve effective correction of aberrations in the optical system, in this embodiment, for the infrared imaging system, the long-wave infrared light after passing through the spectrometer produces certain aberrations, and the imaging quality of the horizontal field of view and the vertical field of view are not the same. It is necessary to correct the aberrations of the horizontal field of view and the vertical field of view at the same time. Therefore, an off-axis second positive lens 41 and a second negative lens 42 are added to the rear stage of the spectrometer 2, and the optical path image is corrected and then projected into the infrared imaging element.

[0148] The maximum field of view angles of the horizontal and vertical fields of view are both 14°, the focal length is 8.4mm, the total length of the system is 54.2mm, and the entrance pupil diameter is 11.04mm.

[0149] The system parameters of the infrared imaging system are shown in Table 3:

[0150]

[0151]

[0152] Table 3

[0153] To achieve the correction of aberration, the concave surface of the first lens 11, the primary mirror 12 and the secondary mirror 13, and the convex surface of the second positive lens 41 close to the beam splitter 2 are aspherical surfaces, which can well balance the aberration formed by the light passing through the refractive lens group.

[0154] Among them, the surface formula of the aspheric surface is:

[0155]

[0156] Where z is the arrow height;

[0157] c is the curvature at the vertex of the surface;

[0158] r is the distance between the projection of the surface point coordinates on the plane perpendicular to the optical axis and the optical axis;

[0159] k is the cone coefficient;

[0160] a1a2a3a4a5a6a7 and a8 represent the coefficients corresponding to the even-order terms.

[0161] The surface parameters of multiple aspheric surfaces in the long-wave infrared light system are shown in Table 4. The surface numbers on the left side of Table 4 correspond to the numbers of each surface in Table 3.

[0162]

[0163] Table 4

[0164] Furthermore, a surface of the second negative lens close to the image plane is a diffraction surface, which is used to further correct chromatic aberration.

[0165] The shape of the diffraction surface is defined by the following formula:

[0166]

[0167] Where z is the arrow height;

[0168] c is the curvature at the vertex of the surface;

[0169] r is the distance between the projection of the surface point coordinates on the plane perpendicular to the optical axis and the optical axis;

[0170] k is the cone coefficient;

[0171] A is the fourth-order aspheric coefficient;

[0172] B is the sixth-order aspheric coefficient;

[0173] C is the eighth-order aspheric coefficient;

[0174] D is the tenth-order aspheric coefficient;

[0175] HOR is the diffraction order;

[0176] C1, C2, and C3 are diffraction surface coefficients;

[0177] λ0 is the designed central wavelength;

[0178] n is the refractive index of the lens;

[0179] n0 is the refractive index of air.

[0180] The parameters of the diffraction surface are shown in Table 5:

[0181]

[0182] Table 5

[0183] The point array test diagram of the above system is as follows Figure 7 As shown, the modulation transfer function curve is as follows Figure 8 shown.

[0184] The modulation transfer function curve of the long-wave infrared light imaging system has a value of about 0.2 at 20 cycles / mm and a value of about 0.1 at 50 cycles / mm. The diffuse spot radius of the imaging system is less than or equal to 83.4 μm, and infrared thermal imaging can be achieved.

[0185] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A catadioptric visible light and long-wave infrared dual-band imaging system, characterized in that: It includes a catadioptric lens group, a beam splitter, a visible light imaging module and an infrared imaging module; The catadioptric lens group, the beam splitter and the infrared imaging module are arranged on the same optical axis; The first light emitting surface of the beam splitter points to the infrared imaging module; The second light emitting surface of the beam splitter points to the visible light imaging module; The optical axis of the visible light imaging module is arranged perpendicularly to the optical axis of the catadioptric lens group.

2. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 1, characterized in that: The catadioptric lens group includes a first lens, a primary reflector and a secondary reflector; The first lens is a plano-concave lens; The reflector primary mirror is a reflector with a central opening; The optical axes of the first lens and the reflector secondary mirror are aligned with the central opening of the reflector primary mirror.

3. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 2, characterized in that: The concave surface of the first lens, the primary reflector and the secondary reflector are all aspherical mirrors; The vertex curvature of the concave surface of the first lens is 1 / 38.913, the cone coefficient is 0, the coefficient of the second even-order term is -1.3095e-05, the coefficient of the third even-order term is 2.7889e-08, and the coefficient of the fourth even-order term is 1.9072e-10; The curvature of the vertex of the curved surface of the primary mirror of the reflector is 1 / 30.264, the cone coefficient is 0, the coefficient of the second even-order term is 3.8131e-07, the coefficient of the third even-order term is 1.3351e-10, and the coefficient of the fourth even-order term is -6.0730e-14; The vertex curvature of the curved surface of the secondary mirror of the reflector is 1 / 20.733, the cone coefficient is 0, the coefficient of the second even-order term is 1.4139e-05, the coefficient of the third even-order term is 2.6733e-08, the coefficient of the fourth even-order term is 1.5797e-11, and the coefficient of the fifth even-order term is 6.5914e-13.

4. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 1, characterized in that: The beam splitter is a flat beam splitter; The beam splitter is located at 15.8 mm along the optical axis of the aperture; The spectroscope substrate material is chalcogenide glass; The beam splitter is arranged at 45° relative to the main optical axis.

5. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 2, characterized in that: The material of the first lens is barium fluoride.

6. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 1, characterized in that: The visible light imaging module includes a first positive lens, a first negative lens, a first cover glass, and a second cover glass; The first positive lens is a biconvex mirror; The first negative lens is a double concave mirror; A visible light imaging element is arranged behind the second cover glass.

7. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 6, characterized in that: The convex surface of the first positive lens facing the first negative lens is an aspherical surface; The vertex curvature of the convex surface of the first positive lens facing the first negative lens is 1 / -173.247, the cone coefficient is 0, the coefficient of the second even-order term is 8.894e-05, the coefficient of the third even-order term is -6.9346e-07, the coefficient of the fourth even-order term is 3.9486e-09, and the coefficient of the fifth even-order term is -9.9823e-12.

8. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 1, characterized in that: The infrared imaging module includes a second positive lens and a second negative lens; The second positive lens is a positive meniscus lens; The second negative lens is a negative meniscus lens, and an infrared imaging element is arranged behind the second negative lens.

9. The catadioptric visible light and long-wave infrared dual-band imaging system according to claim 8, characterized in that: The convex surface of the second positive lens close to the beam splitter is an aspherical mirror; The vertex curvature of the convex surface of the second positive lens close to the beam splitter is 1 / 12.43, the cone coefficient is 0, the coefficient of the second even-order term is 4.7821e-06, the coefficient of the third even-order term is -7.4629e-08, and the coefficient of the fourth even-order term is 1.0791e-09; The side of the second negative lens close to the image plane is a diffraction surface, the vertex curvature of the convex surface of the diffraction surface is 1 / 11.238, the cone coefficient is 0, the fourth-order aspheric coefficient is 0, the sixth-order aspheric coefficient is 0, the first diffraction surface coefficient is -0.0301, the second diffraction surface coefficient is 0.0007, the design central wavelength is 11000nm, the lens refractive index is 3.1351, and the diffraction order is 1.

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