阅读说明：本技术 一种机载中波制冷红外连续变焦光学系统 (Airborne medium wave refrigeration infrared continuous zooming optical system ) 是由 吴海清 李同海 赵新亮 谈大伟 曾宪宇 王朋 于 2019-09-29 设计创作，主要内容包括：一种机载中波制冷红外连续变焦光学系统,采用正组机械补偿、三次成像、连续变焦、三平面反射镜设计,减小了光学系统长度,同时具有较大的系统焦距；经光学及镜头设计,在满足系统成像质量的前提下,得到仅采用9片镜头的组合,具有透过率高、系统高灵敏度高的特点,同时有效控制了光学系统总长度；系统设置有视场光阑结构,降低了杂散光对系统成像的影响,提高了系统信噪比；采用冷光阑,且实现效率100％,提高了系统灵敏度及信噪比；通过三个平面反射镜改变系统光轴方向,缩短光学系统总长度；该红外连续变焦光学系统具有最小焦距大,成像质量高,光学总长小,变倍、补偿结构简单,信噪比、灵敏度高的优点,处于国内同类产品的领先水平。(An airborne medium wave refrigeration infrared continuous zooming optical system adopts the design of positive group mechanical compensation, three-time imaging, continuous zooming and a three-plane reflector, reduces the length of the optical system and has larger system focal length; through optical and lens design, on the premise of meeting the imaging quality of the system, the combination of only 9 lenses is obtained, and the optical system has the characteristics of high transmittance and high sensitivity of the system, and simultaneously effectively controls the total length of the optical system; the system is provided with a field diaphragm structure, so that the influence of stray light on system imaging is reduced, and the signal-to-noise ratio of the system is improved; a cold diaphragm is adopted, the efficiency is realized by 100%, and the system sensitivity and the signal-to-noise ratio are improved; the direction of the optical axis of the system is changed through the three plane reflectors, and the total length of the optical system is shortened; the infrared continuous zooming optical system has the advantages of large minimum focal length, high imaging quality, small optical total length, zooming, simple compensation structure, high signal-to-noise ratio and high sensitivity, and is in the leading level of domestic similar products.)

1. An airborne medium wave refrigeration infrared continuous zooming optical system is characterized in that: the system adopts positive group mechanical compensation, three-time imaging and continuous zooming design; comprises a front fixed group, a zoom group, a compensation group, a rear fixed group and an infrared detector (13); the front fixed group comprises a first positive meniscus lens (1) and a second positive meniscus lens (2); the variable power group comprises a double concave negative lens (3); the compensation group comprises a third positive meniscus lens (4); the rear fixed group comprises a fourth positive meniscus lens (5), a fifth negative meniscus lens (6), a sixth positive meniscus lens (7), a seventh positive meniscus lens (9) and an eighth positive meniscus lens (12); the front fixed group, the zoom group, the compensation group and the rear fixed group are totally 9 optical lenses; the front fixed group, the zoom group, the compensation group, the rear fixed group and the infrared detector (13) are sequentially arranged from left to right and arranged in a coaxial manner; the infrared detector (13) is a medium wave refrigeration detector, and the infrared detector (13) is arranged on a third image plane; in the zooming process, the zooming group and the compensation group move reversely along the optical axis, and the front fixed group, the rear fixed group and the infrared detector (13) are kept in situ.

2. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 1, characterized in that: in the zooming process, the zooming group and the compensation group move along the optical axis according to different motion rules, and the motion rules are realized through the control of two cams; the envelope curves of the two cams are respectively the motion law curves of the zoom group and the compensation group.

3. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 1, characterized in that: a first plane reflector (8), a second plane reflector (10) and a third plane reflector (11) are arranged in the rear fixing group; the first plane reflector (8) is arranged between the sixth positive meniscus lens (7) and the seventh positive meniscus lens (9); the second plane mirror (10) is arranged behind the seventh positive meniscus lens (9); the third plane mirror (11) is arranged behind the second plane mirror (10); and the normal lines of the first plane reflector (8), the second plane reflector (10) and the third plane reflector (11) form 45-degree included angles with the optical axis.

4. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 1, characterized in that: the focal lengths of the above lenses need to satisfy the following conditions:

230f≤f1≤231f，2.45f≤f2≤2.60f，-0.75f≤f3≤-0.6f，1.6f≤f4≤1.7f，0.95f≤f5≤1.1f，1.2f≤f6≤1.35f，0.2f≤f7≤0.3f，0.95f≤f9≤1.05f，0.62f≤f12≤0.70f；

wherein: f is the focal length of the optical system in the short focus,

f1 is the effective focal length of the first positive meniscus lens (1),

f2 is the effective focal length of the second meniscus positive lens (2),

f3 is the effective focal length of the double concave negative lens (3),

f4 is the effective focal length of the third meniscus positive lens (4),

f5 is the effective focal length of the fourth meniscus positive lens (5),

f6 is the effective focal length of the fifth negative meniscus lens (6),

f7 is the effective focal length of the sixth meniscus positive lens (7),

f9 is the effective focal length of the seventh meniscus positive lens (9),

f12 is the effective focal length of the eighth meniscus positive lens (12).

5. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 1, characterized in that: the light incidence side surfaces of the biconcave negative lens (3) and the fifth meniscus negative lens (6) are both of even-order aspheric surface types.

6. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 5, characterized in that: the surface type equation of the incident side of the double concave negative lens (3) is as follows:

wherein: c. C₃Is the curvature of the light incident side surface of the biconcave negative lens (3), r₃Is a radial coordinate, k, of the incident side surface of the biconcave negative lens (3) perpendicular to the optical axis direction₃Is a conic constant of the incident light side surface of the biconcave negative lens (3), A₃Is a fourth-order aspheric coefficient of the incident light side surface of the biconcave negative lens (3), B₃A six-order aspheric surface coefficient, C, of the incident light side surface of the biconcave negative lens (3)₃Is an eight-order aspheric coefficient of the light-incident side surface of the biconcave negative lens (3).

7. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 5, characterized in that: the surface equation of the incident side of the fifth meniscus negative lens (6) is as follows:

wherein: c. C₆Is the curvature of the light-incident side surface of the fifth meniscus negative lens (6), r₆Is a radial coordinate, k, of the incident-side surface of the fifth meniscus negative lens (6) in a direction perpendicular to the optical axis₆Is a conic constant of the incident-side surface of the fifth meniscus negative lens (6), A₆Is a fourth-order aspheric coefficient of the incident light side surface of the fifth meniscus negative lens (6), B₆Is a sixth-order aspheric coefficient, C, of the incident-light-side surface of the fifth meniscus negative lens (6)₆Is an eighth-order aspheric coefficient of the light-incident side surface of the fifth meniscus negative lens (6).

8. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 1, characterized in that: the surface of the light incident side of the fourth meniscus positive lens (5) adopts a diffraction aspheric surface, and the aspheric surface and the diffraction surface act on the same lens surface; the surface equation of the light incident side of the fourth meniscus positive lens (5) is as follows:

wherein, c₅Is the curvature of the light-incident side surface of the fourth meniscus positive lens (5), r₅Is a radial coordinate, k, of the incident-side surface of the fourth meniscus positive lens (5) in a direction perpendicular to the optical axis₅Is a conic constant of the incident-side surface of the fourth meniscus positive lens (5), A₅Is a fourth-order aspheric coefficient of the light-incident side surface of the fourth meniscus positive lens (5), B₅Is a sixth-order aspheric coefficient, C, of the incident-light-side surface of the fourth meniscus positive lens (5)₅Is an eighth-order aspheric coefficient of the light incidence side surface of the fourth meniscus positive lens (5); HOR is the diffraction order of the incident light side surface of the fourth meniscus positive lens (5), C₁、C₂Is the diffraction coefficient of the light-incident side surface of the fourth positive meniscus lens (5), n is the refractive index of the optical material of the fourth positive meniscus lens (5), n is₀Is the refractive index of air, λ₀The center wavelength is designed for the optical system.

9. The airborne medium wave refrigeration infrared continuous zoom optical system of claim 4, characterized in that: the system is also provided with a field diaphragm and an aperture diaphragm; the field diaphragm is arranged at the image plane of the optical field diaphragm; the aperture diaphragm is a cold wave, and the aperture diaphragm is arranged between the eighth meniscus positive lens (12) of the fixed group and the infrared detector (13).

Technical Field

The invention relates to the technical field of airborne photoelectric pod thermal infrared imagers, in particular to an airborne medium wave refrigeration infrared continuous zooming optical system.

Background

The airborne photoelectric pod system requires that the thermal infrared imager can realize target search of a large field of view and small field of view tracking and identification of a long-distance target, so that an optical system of the thermal infrared imager needs to be designed as a zooming optical system to realize the function;

the target image of the continuous zooming infrared optical system can be kept clear all the time in the zooming process, and the transformation of any view field in the zooming range can be realized; when the system is applied to an airborne photoelectric hanging cabin, the system can ensure that a tracking target cannot be lost in the continuous zooming process, and a proper working view field can be selected according to the scene and the target characteristics, so that the man-machine efficiency is improved;

particularly, the current airborne photoelectric pod system develops towards high integration level, and the number of loaded photoelectric sensors is increased; the infrared thermal imager and other photoelectric sensors can be miniaturized and designed while the performance is guaranteed due to the fact that the size and the weight of an airborne optoelectronic system are limited.

Disclosure of Invention

In order to overcome the defects in the background art, the invention discloses an airborne medium-wave refrigeration infrared continuous zooming optical system which adopts positive group mechanical compensation, three-time imaging and continuous zooming design, reduces the length of the optical system and has larger minimum focal length of the system; through optical and lens design, on the premise of meeting the imaging quality of the system, the combination of only 9 lenses is obtained, so that the optical system has higher transmittance, the sensitivity of the system is improved, and the total length of the optical system is effectively controlled; the cylindrical cam is adopted to control the movement of the zooming group and the compensation group, and the compensation structure has the advantage of simple compensation structure; the field diaphragm structure is added, so that the influence of stray light on system imaging is reduced, and the signal-to-noise ratio of the system is improved; the cold diaphragm is adopted, the efficiency is realized by 100%, the energy loss of light beams is reduced, the system noise is inhibited, and the system sensitivity and the signal-to-noise ratio are improved; the direction of the optical axis of the system is changed three times through the three plane reflectors, the total length of the optical system is effectively shortened, and the split type refrigeration infrared detector is particularly suitable for being used.

In order to realize the purpose, the invention adopts the following technical scheme: an airborne medium-wave refrigeration infrared continuous zooming optical system adopts positive set mechanical compensation, three-time imaging and continuous zooming design, realizes larger minimum focal length and simultaneously has smaller total length of the optical system; the device comprises a front fixed group, a zoom group, a compensation group, a rear fixed group and an infrared detector; the front fixed group comprises a first positive meniscus lens and a second positive meniscus lens; the variable power group comprises a double concave negative lens; the compensation group comprises a third positive meniscus lens; the rear fixed group comprises a fourth meniscus positive lens, a fifth meniscus negative lens, a sixth meniscus positive lens, a seventh meniscus positive lens and an eighth meniscus positive lens; the front fixed group, the zoom group, the compensation group and the rear fixed group are totally 9 optical lenses; the front fixed group, the zooming group, the compensation group, the rear fixed group and the infrared detector are sequentially arranged from left to right and arranged in a coaxial way; the infrared detector is a medium wave refrigeration detector, the detector and the refrigeration device are arranged separately, and the infrared detector is arranged on a third image plane; in the zooming process, the zooming group and the compensation group move reversely along the optical axis, and the front fixed group, the rear fixed group and the infrared detector are kept in situ.

Furthermore, in the zooming process, the zooming group and the compensation group move along the optical axis according to different motion rules, and the motion rules are realized through the control of two cylindrical cams; when the system changes from short focus to long focus, the zoom group and the compensation group respectively move from two sides to the middle; the motion rules of the zoom group and the compensation group are realized by controlling two cylindrical cams; the envelope curves of the two cylindrical cams are respectively the motion law curves of the zoom group and the compensation group.

Furthermore, a first plane reflector, a second plane reflector and a third plane reflector are arranged in the rear fixing group; the first plane reflector is arranged between the sixth positive meniscus lens and the seventh positive meniscus lens; the second plane mirror is arranged behind the seventh meniscus positive lens; the third plane mirror is arranged behind the second plane mirror; the normal lines of the first plane reflector, the second plane reflector and the third plane reflector form an included angle of 45 degrees with the optical axis; the three plane reflectors change the direction of the optical axis of the system three times, the total length of the optical system is effectively shortened, and the split type refrigeration infrared detector is particularly suitable for being used.

Further, the focal lengths of the above lenses need to satisfy the following conditions:

230f≤f1≤231f，2.45f≤f2≤2.60f，-0.75f≤f3≤-0.6f，1.6f≤f4≤1.7f，0.95f≤f5≤1.1f，1.2f≤f6≤1.35f，0.2f≤f7≤0.3f，0.95f≤f9≤1.05f， 0.62f≤f12≤0.70f；

wherein: f is the focal length of the optical system in the short focus,

f1 is the effective focal length of the first positive meniscus lens,

f2 is the effective focal length of the second positive meniscus lens,

f3 is the effective focal length of the biconcave negative lens,

f4 is the effective focal length of the third positive meniscus lens,

f5 is the effective focal length of the fourth positive meniscus lens,

f6 is the effective focal length of the fifth meniscus negative lens,

f7 is the effective focal length of the sixth positive meniscus lens,

f9 is the effective focal length of the seventh meniscus positive lens,

f12 is the effective focal length of the eighth positive meniscus lens.

Furthermore, the light incidence side surfaces of the double-concave negative lens and the fifth meniscus negative lens are both of even aspheric surface type; the method is used for improving imaging aberration and distortion of the system and ensuring the molding quality.

Further, the surface equation of the light incident side of the double concave negative lens is as follows:

wherein: c. C₃Is the curvature of the incident-light side surface of the biconcave negative lens, r₃Is a radial coordinate, k, of the incident-side surface of the biconcave negative lens perpendicular to the optical axis₃Is the conic constant of the incident-side surface of the biconcave negative lens, A₃Fourth order aspheric surface coefficient of the incident light side surface of the biconcave negative lens, B₃A sixth-order aspheric coefficient, C, of the incident-light-side surface of the biconcave negative lens₃Is an eight-order aspheric surface coefficient of the light incidence side surface of the biconcave negative lens.

Further, the surface equation of the light incident side of the fifth meniscus negative lens is as follows:

wherein: c. C₆Is the curvature of the incident-light-side surface of the fifth meniscus negative lens, r₆Is a radial coordinate, k, of the incident-side surface of the fifth meniscus negative lens in the direction perpendicular to the optical axis₆Is the conic constant of the incident-side surface of the fifth meniscus negative lens, A₆Is a fourth-order aspheric coefficient of the incident light side surface of the fifth meniscus negative lens, B₆A sixth-order aspheric coefficient, C, of the incident-light-side surface of the fifth meniscus negative lens₆Is an eighth-order aspheric coefficient of the light-incident side surface of the fifth meniscus negative lens.

Furthermore, the surface of the light incident side of the fourth meniscus positive lens adopts a diffractive aspheric surface for improving imaging aberration, distortion and resolution of the system, and the aspheric surface and the diffractive surface act on the same lens surface; the surface equation of the light incident side of the fourth meniscus positive lens is as follows:

wherein, c₅Is the curvature of the light incident side surface of the fourth meniscus positive lens, r₅Is a radial coordinate, k, of the incident-light side surface of the fourth meniscus positive lens in the direction perpendicular to the optical axis₅Is a conic constant of the incident-side surface of the fourth meniscus positive lens, A₅Is a fourth-order aspheric coefficient of the incident light side surface of the fourth meniscus positive lens, B₅A sixth-order aspheric coefficient, C, of the incident-light-side surface of the fourth meniscus positive lens₅An eighth-order aspheric coefficient of the light incidence side surface of the fourth meniscus positive lens; HOR is the diffraction order of the incident light side surface of the fourth meniscus positive lens, C₁、C₂Is the diffraction coefficient of the light incidence side surface of the fourth meniscus positive lens, n is the refractive index of the optical material of the fourth meniscus positive lens, n₀Is the refractive index of air, λ₀The center wavelength is designed for the optical system.

Furthermore, the system is also provided with a field diaphragm and an aperture diaphragm; the field diaphragm is arranged on the image plane of the optical field diaphragm and used for filtering stray light outside a field of view and providing a system signal-to-noise ratio; the aperture diaphragm is in a cold-looking wave shape, the cold-looking wave efficiency is 100%, and light loss is avoided; the aperture is used for filtering noise in the system and improving the sensitivity and the signal-to-noise ratio of the system; and the aperture diaphragm is arranged between the eighth meniscus positive lens of the fixed group and the infrared detector.

Due to the adoption of the technical scheme, the invention has the following beneficial effects: the invention discloses an airborne medium-wave refrigeration infrared continuous zooming optical system, which adopts the design of positive group mechanical compensation, three-time imaging, continuous zooming and a three-plane reflector, reduces the length of the optical system and has larger minimum focal length of the system; through the optical and lens structure design, on the premise of meeting the imaging quality of the system, the combination of only 9 lenses is obtained, so that the optical system has higher transmittance, the system sensitivity is improved, and the total length of the optical system is effectively controlled; the cylindrical cam is adopted to control the movement of the zooming group and the compensation group, and the compensation structure has the advantage of simple compensation structure; the field diaphragm structure is added, so that the influence of stray light on system imaging is reduced, and the signal-to-noise ratio of the system is improved; the cold diaphragm is adopted, the efficiency is 100 percent, the energy loss of light beams is reduced, and the sensitivity and the signal-to-noise ratio of the system are improved; the direction of the optical axis of the system is changed for three times through the three plane reflectors, so that the total length of the optical system is effectively shortened, and the split type refrigeration infrared detector is suitable for being used; the continuous zooming infrared optical system has the advantages of high imaging quality, small optical total length, zooming, simple compensation structure, signal-to-noise ratio and high sensitivity, meets the requirements of an airborne photoelectric pod system with strict requirements on the volume, weight and imaging quality of the optical system, and is at the leading level of domestic similar products.

Drawings

FIG. 1 is a diagram of an optical path of the optical system at a focal length of 40 mm;

FIG. 2 is a diagram of the optical path of the optical system at a focal length of 240 mm;

FIG. 3 is a diagram of the optical path of the optical system at a focal length of 400 mm;

FIG. 4 is a graph of the transfer function for a focal length of 400 mm;

FIG. 5 is a graph of the transfer function for a focal length of 240 mm;

FIG. 6 is a diagram of the transfer function of the optical system at a focal length of 40 mm;

FIG. 7 is a dot diagram of the optical system at a focal length of 400 mm;

FIG. 8 is a dot diagram of the optical system at a focal length of 240 mm;

FIG. 9 is a diagram of a focal length of the optical system at 40 mm;

FIG. 10 is a diagram showing the relationship between the phase period and the radial distance of the diffraction element of the optical system.

In the figure: 1. a first meniscus positive lens; 2. a second meniscus positive lens; 3. a biconcave negative lens; 4. a third meniscus positive lens; 5. a fourth meniscus positive lens; 6. a fifth negative meniscus lens; 7. a sixth meniscus positive lens; 8. a first planar mirror; 9. a seventh meniscus positive lens; 10. a second planar mirror; 11. A third plane mirror; 12. an eighth meniscus positive lens; 13. an infrared detector.

Detailed Description

The present invention will be explained in detail by the following examples, which are disclosed for the purpose of protecting all technical improvements within the scope of the present invention.

An airborne medium-wave refrigeration infrared continuous zooming optical system adopts positive set mechanical compensation, three-time imaging and continuous zooming design; comprises a front fixed group, a zoom group, a compensation group, a rear fixed group and an infrared detector 13; the front fixed group comprises a first positive meniscus lens 1 and a second positive meniscus lens 2; the variable power group comprises a double concave negative lens 3; the compensation group comprises a third positive meniscus lens 4; the rear fixed group comprises a fourth positive meniscus lens 5, a fifth negative meniscus lens 6, a sixth positive meniscus lens 7, a seventh positive meniscus lens 9 and an eighth positive meniscus lens 12; the front fixed group, the zoom group, the compensation group and the rear fixed group are totally 9 optical lenses; the front fixed group, the zooming group, the compensation group, the rear fixed group and the infrared detector 13 are sequentially arranged from left to right and arranged in a coaxial manner; the infrared detector 13 is a medium wave refrigeration detector, and the infrared detector 13 is arranged on a third image plane; in the zooming process, the zooming group and the compensation group move reversely along the optical axis, and the front fixed group, the rear fixed group and the infrared detector 13 are kept in situ; the system is also provided with a field diaphragm and an aperture diaphragm; the field diaphragm is arranged at the image plane of the optical field diaphragm; the aperture diaphragm is a cold wave, and is arranged between the eighth meniscus positive lens 12 of the fixed group and the infrared detector 13;

in the zooming process, the zooming group and the compensation group move along the optical axis according to different motion rules, and the motion rules are realized through the control of two cams; the envelope curves of the two cams are respectively motion law curves of the zoom group and the compensation group;

a first plane reflector 8, a second plane reflector 10 and a third plane reflector 11 are arranged in the rear fixing group; the first plane mirror 8 is arranged between the sixth meniscus positive lens 7 and the seventh meniscus positive lens 9; the second plane mirror 10 is arranged behind the seventh meniscus positive lens 9; the third plane mirror 11 is arranged behind the second plane mirror 10; the normal lines of the first plane reflector 8, the second plane reflector 10 and the third plane reflector 11 form an included angle of 45 degrees with the optical axis;

the focal lengths of the above lenses need to satisfy the following conditions:

230f≤f1≤231f，2.45f≤f2≤2.60f，-0.75f≤f3≤-0.6f，1.6f≤f4≤1.7f，0.95f≤f5≤1.1f，1.2f≤f6≤1.35f，0.2f≤f7≤0.3f，0.95f≤f9≤1.05f， 0.62f≤f12≤0.70f；

wherein: f is the focal length of the optical system in the short focus,

f1 is the effective focal length of the first positive meniscus lens 1,

f2 is the effective focal length of the second positive meniscus lens 2,

f3 is the effective focal length of the biconcave negative lens 3,

f4 is the effective focal length of the third positive meniscus lens 4,

f5 is the effective focal length of the fourth positive meniscus lens 5,

f6 is the effective focal length of the fifth meniscus negative lens 6,

f7 is the effective focal length of the sixth positive meniscus lens 7,

f9 is the effective focal length of the seventh meniscus positive lens 9,

f12 is the effective focal length of the eighth positive meniscus lens 12.

The light incidence side surfaces of the biconcave negative lens 3 and the fifth meniscus negative lens 6 are both of even-order aspheric surface shapes;

the surface equation of the light incident side of the biconcave negative lens 3 is as follows:

wherein: c. C₃Is a biconcave negativeCurvature of light-incident side surface of lens 3, r₃Is a radial coordinate, k, perpendicular to the optical axis direction of the light-incident side surface of the biconcave negative lens 3₃Is the conic constant of the incident-side surface of the biconcave negative lens 3, A₃Fourth order aspheric surface coefficient B of the light incident side surface of the biconcave negative lens 3₃A sixth-order aspheric coefficient, C, of the light incident surface of the biconcave negative lens 3₃Is an eighth order aspheric surface coefficient of the light incident side surface of the biconcave negative lens 3.

The surface equation of the light incident side of the fifth meniscus negative lens 6 is as follows:

wherein: c. C₆Is the curvature of the light-incident side surface of the fifth meniscus negative lens 6, r₆Is a radial coordinate, k, of the incident-side surface of the fifth meniscus negative lens 6 in the direction perpendicular to the optical axis₆Is a conic constant of the incident-side surface of the fifth meniscus negative lens 6, A₆Is a fourth-order aspheric coefficient of the incident light side surface of the fifth meniscus negative lens 6, B₆A sixth-order aspheric coefficient, C, of the incident-light-side surface of the fifth meniscus negative lens 6₆Is an eighth-order aspheric coefficient of the light-incident-side surface of the fifth meniscus negative lens 6.

The surface of the light incident side of the fourth meniscus positive lens 5 adopts a diffraction aspheric surface, and the aspheric surface and the diffraction surface act on the same lens surface; the surface equation of the light incident side of the fourth meniscus positive lens 5 is as follows:

wherein, c₅Is the curvature of the light-incident side surface of the fourth meniscus positive lens 5, r₅Is a radial coordinate, k, of the light-incident side surface of the fourth meniscus positive lens 5 in the direction perpendicular to the optical axis₅Is a conic constant of the incident-side surface of the fourth meniscus positive lens 5, A₅Is a fourth-order aspheric coefficient of the light incident surface of the fourth meniscus positive lens 5, B₅A sixth-order aspheric coefficient, C, of the incident-light-side surface of the fourth meniscus positive lens 5₅An eighth-order aspheric coefficient of the light-incident-side surface of the fourth meniscus positive lens 5; HOR is the diffraction order of the light-incident surface of the fourth meniscus positive lens 5, C₁、C₂Is the diffraction coefficient of the light-incident side surface of the fourth positive meniscus lens 5, n is the refractive index of the optical material of the fourth positive meniscus lens 5, n₀Is the refractive index of air, λ₀The center wavelength is designed for the optical system.

Based on the technical characteristics of the airborne medium wave refrigeration infrared continuous zooming optical system such as the configuration of each optical lens and device, the design of light path, the focal length of each optical lens and the design rule of each lens surface type, the following preferred embodiments are provided by combining the specific technical indexes realized by the system:

the specific technical indexes are as follows:

wave band: 3.7-4.8 μm; relative pore diameter: 1: 5.5; focal length: 40 mm-400 mm; image plane size: 19.2X 15.4;

table 1 lists detailed data of embodiments of the optical system according to the present invention including the face type, radius of curvature, thickness, caliber, material of each lens at focal lengths of 40mm to 400 mm. Wherein the unit of curvature radius, thickness and caliber of the lens is mm;

TABLE 1

Table 2 lists the aspherical coefficients of the light-incident side surface of the biconcave negative lens 3 according to the present invention;

TABLE 2

Table 3 lists aspherical coefficients of the image side surface of the fifth meniscus positive lens 6 according to the present invention;

TABLE 3

Table 4 lists the diffractive aspheric coefficients of the light-entering side of the fourth positive meniscus lens 5 according to the invention;

TABLE 4

When the airborne medium wave refrigeration infrared continuous zooming optical system works, the specific light transmission process is as follows: the light emitted by the object plane reflecting natural light is converged by the first positive meniscus lens 1 to reach the second positive meniscus lens 2, converged by the second positive meniscus lens 2 to reach the double concave negative lens 3, diverged by the double concave negative lens 3 to reach the third positive meniscus lens 4, converged by the third positive meniscus lens 4 to reach the fourth positive meniscus lens 5, converged by the fourth positive meniscus lens 5 to reach the fifth positive meniscus lens 6, converged by the fifth positive meniscus lens 6 to reach the sixth positive meniscus lens 7, converged by the sixth positive meniscus lens 7 to reach the first plane mirror 8, reflected by the first plane mirror 8 to reach the seventh positive meniscus lens 9, converged by the seventh positive meniscus lens 9 to reach the second plane mirror 10, reflected by the second plane mirror 10 to reach the third plane mirror 11, reflected by the third plane mirror 11 to reach the eighth positive meniscus lens 12, the image is focused by the eighth meniscus positive lens 12 and then is imaged on the infrared detector 13.

When the airborne medium wave refrigeration infrared continuous zooming optical system works, the motion laws of the zooming group and the compensation group are as follows: when the optical system is in short focus, the zoom group is close to the object space position, and the compensation group is close to the image space position; in the process of changing from short coke to long coke, the zoom group and the compensation group respectively move towards the middle from two sides; the focal length change is realized by the movement of the zoom group along the optical axis, and the image plane defocusing caused by the movement of the zoom group is compensated by the movement of the compensation group along the optical axis, so that the clear imaging of the whole zooming process is realized.

The present invention is not described in detail in the prior art.