阅读说明：本技术 一种小型化负补偿式中波制冷红外连续变焦光学系统 (Miniaturized negative compensation type medium-wave refrigeration infrared continuous zooming optical system ) 是由 吴海清 赵新亮 李同海 崔莉 田海霞 谈大伟 于 2019-10-30 设计创作，主要内容包括：一种小型化负补偿式中波制冷红外连续变焦光学系统,采用负组机械补偿、二次成像、连续变焦、三反射镜设计,减小了光学系统长度,同时具有较大的系统最小焦距；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,具有较高的透过率,提高了系统灵敏度；增加视场光阑结构,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％,减少了光束能量损失,抑制了系统噪声,提高了系统灵敏度及信噪比；通过三个平面反射镜三次改变系统光轴方向,有效缩短光学系统总长度,满足了对光学系统体积、重量、成像质量都有严苛要求的机载光电吊舱系统的需求,处于国内同类产品的领先水平。(A miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system adopts negative group mechanical compensation, secondary imaging, continuous zooming and three-reflector 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, the transmittance is high, and the sensitivity of the system is improved; 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 by the three plane reflectors, the total length of the optical system is effectively shortened, the requirement of an airborne photoelectric pod system which has strict requirements on the volume, weight and imaging quality of the optical system is met, and the system is in the leading level of domestic similar products.)

1. A miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system is characterized in that: the system adopts negative group mechanical compensation, secondary 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); the zooming group comprises a first negative meniscus lens (2) and a second negative meniscus lens (3); the compensation group comprises a third negative meniscus lens (4); the rear fixed group comprises a second positive meniscus lens (5), a fourth negative meniscus lens (6), a double convex positive lens (7), a third positive meniscus lens (10) and a fourth 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 second image plane; in the zooming process, the zooming group and the compensation group move along the optical axis, the front fixed group, the rear fixed group and the infrared detector (13) keep in situ, and the distance between the first meniscus negative lens (2) and the second meniscus negative lens (3) of the zooming group keeps constant.

2. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 1, which is 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 miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 1, which is characterized in that: a first plane reflector (8), a second plane reflector (9) and a third plane reflector (11) are arranged in the rear fixing group; the first plane reflector (8) and the second plane reflector (9) are adjacently arranged, and the first plane reflector (8) and the second plane reflector (9) are arranged between the double convex positive lens (7) and the third meniscus positive lens (10); the third plane reflector (11) is arranged between the third positive meniscus lens (10) and the fourth positive meniscus lens (12); and the normal lines of the first plane reflector (8), the second plane reflector (9) and the third plane reflector (11) form 45-degree included angles with the optical axis.

4. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 1, which is characterized in that: the focal lengths of the above lenses need to satisfy the following conditions: f1 is not less than 2.65f and not more than 2.8f, f2 is not less than-1.1 f and not more than-0.9 f, f3 is not less than-1.8 f and not more than 1.9 f: f4 is more than or equal to 1.65f and less than or equal to-1.6 f, f5 is more than or equal to 0.95f and less than or equal to 1.1f, f6 is more than or equal to-1.9 f and less than or equal to 1.95f, f7 is more than or equal to 1.35f and less than or equal to 1.3f, f8 is more than or equal to 2.5f and less than or equal to 2.53f, and f9 is more than or equal to 0.2f and less than or;

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 first negative meniscus lens (2),

f3 is the effective focal length of the second negative meniscus lens (3),

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

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

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

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

f8 is the effective focal length of the third positive meniscus lens (10),

f9 is the effective focal length of the fourth meniscus positive lens (12).

5. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 1, which is characterized in that: the light incidence side surfaces of the first negative meniscus lens (2), the second positive meniscus lens (5) and the double-convex positive lens (7) are all of even aspheric surface shapes.

6. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 5, which is characterized in that: the surface equation of the incident side of the first meniscus negative lens (2) is as follows:

wherein: c. C₁Is the curvature of the incident light side surface of the first meniscus negative lens (2), r₁Is a radial coordinate, k, of the incident-side surface of the first negative meniscus lens (2) perpendicular to the optical axis₁Is a conic constant of the incident-side surface of the first negative meniscus lens (2), A₁Is a fourth-order aspheric coefficient of the incident light side surface of the first meniscus negative lens (2), B₁Is a sixth-order aspheric coefficient, C, of the incident-light-side surface of the first negative meniscus lens (2)₁Is an eighth-order aspheric coefficient of the light-incident side surface of the first negative meniscus lens (2).

7. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 5, which is characterized in that: the surface equation of the light incident side of the second meniscus positive lens (5) is as follows:

wherein: c. C₂Is the curvature of the light incident side surface of the second meniscus positive lens (5), r₂Is a radial coordinate, k, of the incident-side surface of the second meniscus positive lens (5) perpendicular to the optical axis₂Is a conic constant of the incident-side surface of the second meniscus positive lens (5), A₂Is a fourth-order aspheric coefficient of the incident light side surface of the second meniscus positive lens (5), B₂Is a sixth-order aspheric coefficient, C, of the incident-light-side surface of the second meniscus positive lens (5)₂Is an eighth-order aspheric coefficient of the light-incident side surface of the second meniscus positive lens (5).

8. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 5, which is characterized in that: the surface type equation of the light incident side of the biconvex positive lens (7) is as follows:

wherein: c. C₃Is the curvature of the light incident side surface of the biconvex positive lens (7), r₃Is a radial coordinate, k, of the light incident side surface of the biconvex positive lens (7) perpendicular to the optical axis₃Is a conic constant of the incident light side surface of the biconvex positive lens (7), A₃A fourth-order aspheric coefficient B of the light incident surface of the biconvex positive lens (7)₃A sixth-order aspheric coefficient C of the light incident surface of the biconvex positive lens (7)₃Is an eighth-order aspheric surface coefficient of the light incident side surface of the biconvex positive lens (7).

9. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 1, which is characterized in that: the surface of the light emitting side of the fourth positive meniscus lens (12) adopts a diffractive aspheric surface, the aspheric surface and the diffractive surface act on the same lens surface, and the surface equation is as follows:

wherein, c₅Is the curvature of the light-emitting side surface of the fourth meniscus positive lens (12), r₅Is a radial coordinate, k, of the light-emitting side surface of the fourth meniscus positive lens (12) in the direction perpendicular to the optical axis₅Is a conic constant of the light-emitting side surface of the fourth meniscus positive lens (12), A₅Is a fourth-order aspheric coefficient of the light-emitting side surface of the fourth meniscus positive lens (12), B₅A sixth-order aspheric coefficient, C, of the light-emitting side surface of the fourth meniscus positive lens (12)₅An eighth-order aspheric coefficient of the light-emitting side surface of the fourth meniscus positive lens (12); HOR is the diffraction order of the light-emitting side surface of the fourth meniscus positive lens (12), C₁、C₂Is the diffraction coefficient of the light-emitting side surface of the fourth positive meniscus lens (12), n is the refractive index of the optical material of the fourth positive meniscus lens (12), n is₀Is the refractive index of air, λ₀The center wavelength is designed for the optical system.

10. The miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system of claim 1, which is 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 fourth 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 a miniaturized negative compensation type 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 continuous 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 a miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system, which adopts the design of negative group mechanical compensation, secondary imaging, continuous zooming and three-time system optical axis direction change, reduces the length of the optical system and has larger system minimum 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, 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 three plane reflectors, so that the total length of the optical system is effectively shortened; the invention meets the requirement of an airborne photoelectric pod system with strict requirements on the volume, weight and imaging quality of an optical system, and is in the leading level of domestic similar products.

In order to realize the purpose, the invention adopts the following technical scheme:

a miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system adopts negative group mechanical compensation, secondary imaging and continuous zooming design; 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 meniscus positive lens; the variable power group comprises a first negative meniscus lens and a second negative meniscus lens; the compensation group comprises a third negative meniscus lens; the rear fixed group comprises a second positive meniscus lens, a fourth negative meniscus lens, a double-convex positive lens, a third positive meniscus lens and a fourth positive meniscus 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 and is arranged on the second image plane; in the zooming process, the zooming group and the compensation group move along the optical axis, the front fixed group, the rear fixed group and the infrared detector are kept in situ, and the distance between the first meniscus negative lens and the second meniscus negative lens of the zooming group is kept constant.

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 cams; when the system is in short focus, the zoom group is at the position close to the object space, and the compensation group is at the position close to the image space; when the system changes from short focus to long focus, the zoom group and the compensation group are close to each other on the optical axis and then move to the image space together; 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 and the second plane reflector are arranged adjacently, and the first plane reflector and the second plane reflector are arranged between the double convex positive lens and the third meniscus positive lens; the third plane reflector is arranged between the third positive meniscus lens and the fourth positive meniscus lens; 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, and the total length of the optical system is effectively shortened.

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

2.65f≤f1≤2.8f，-1.1f≤f2≤-0.9f，-1.9f≤f3≤-1.8f，：-1.65f≤f4≤-1.6f，0.95f≤f5≤1.1f，-1.95f≤f6≤-1.9f，1.3f≤f7≤1.35f，2.5f≤f8≤2.53f，0.2f≤f9≤0.3f；

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 first negative meniscus lens,

f3 is the effective focal length of the second negative meniscus lens,

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

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

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

f7 is the effective focal length of a biconvex positive lens,

f8 is the effective focal length of the third positive meniscus lens,

f9 is the effective focal length of the fourth meniscus positive lens.

Furthermore, the light incidence side surfaces of the first negative meniscus lens, the second positive meniscus lens and the double convex positive lens are all even aspheric surface types; for improving imaging aberrations and distortions.

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

wherein: c. C₁Is the curvature of the incident light side surface of the first meniscus negative lens, r₁Is a radial coordinate, k, of the incident-light side surface of the first meniscus negative lens in a direction perpendicular to the optical axis₁Is a conic constant of the incident light side surface of the first meniscus negative lens, A₁Is a fourth-order aspheric coefficient of the incident light side surface of the first meniscus negative lens, B₁A sixth-order aspheric coefficient, C, of the incident light side surface of the first meniscus negative lens₁Is an eighth-order aspheric coefficient of the light-incident side surface of the first negative meniscus lens.

Further, the surface equation of the light incident side of the second meniscus positive lens is as follows:

wherein: c. C₂Is the curvature of the incident light side surface of the second meniscus positive lens, r₂Is a radial coordinate, k, of the incident-light side surface of the second meniscus positive lens in a direction perpendicular to the optical axis₂Is a conic constant of the incident light side surface of the second meniscus positive lens, A₂Is a fourth-order aspheric coefficient of the incident light side surface of the second meniscus positive lens, B₂Is a secondSixth order aspheric surface coefficient, C of incident light side surface of meniscus positive lens₂Is an eighth-order aspheric coefficient of the light-incident side surface of the second meniscus positive lens.

Further, the surface equation of the light incident side of the biconvex positive lens is as follows:

wherein: c. C₃The curvature of the light incident side surface of the biconvex positive lens, r₃Is a radial coordinate, k, perpendicular to the optical axis direction of the light-incident side surface of the biconvex positive lens₃Is the conic constant of the incident-light side surface of the biconvex positive lens, A₃Fourth order aspheric surface coefficient B of the incident light side surface of the biconvex positive lens₃A sixth-order aspheric coefficient, C, of the incident-light-side surface of the biconvex positive lens₃Is an eighth order aspheric surface coefficient of the light incident side surface of the biconvex positive lens.

Furthermore, the surface of the light emergent side of the fourth meniscus positive lens adopts a diffraction aspheric surface, and the aspheric surface and the diffraction surface act on the same lens surface; for improving imaging aberrations, distortion and resolution; the light-emitting side surface equation 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 light-emitting side surface of the fourth meniscus positive lens in the direction perpendicular to the optical axis₅Is a conic constant of the light-emitting side surface of the fourth meniscus positive lens, A₅Is a fourth-order aspheric coefficient of the light-emitting side surface of the fourth meniscus positive lens, B₅A sixth-order aspheric coefficient, C, of the light-emitting side surface of the fourth meniscus positive lens₅An eighth-order aspheric coefficient of the light-emitting side surface of the fourth meniscus positive lens; HOR is the diffraction order of the light-emitting side surface of the fourth meniscus positive lens, C₁、C₂Is the diffraction coefficient of the light-emitting side surface of the fourth meniscus positive lens, and n is the refraction of the optical material of the fourth meniscus positive lensRate, 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, so that the influence of the stray light on the imaging of the optical system can be reduced, and the signal-to-noise ratio of the system is improved; the aperture diaphragm is a cold diaphragm, the cold diaphragm efficiency is 100%, the cold diaphragm is used for inhibiting system noise, and does not cut light beams, so that energy loss is reduced, and the system sensitivity is improved; the aperture diaphragm is arranged between the fourth 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 a miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system, which adopts the design of negative group mechanical compensation, secondary imaging, continuous zooming and three-time system optical axis direction change, reduces the length of the optical system and has larger system minimum 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, 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 by the three plane reflectors, the total length of the optical system is effectively shortened, the requirement of an airborne photoelectric pod system which has strict requirements on the volume, weight and imaging quality of the optical system is met, and the system is in the leading level of domestic similar products.

Drawings

FIG. 1 is a diagram of an optical path of the optical system with a focal length of 55 mm;

FIG. 2 is a diagram of the optical path of the optical system with a focal length of 260 mm;

FIG. 3 is a diagram of the optical path of the optical system with a focal length of 550 mm;

FIG. 4 is a diagram of the transfer function of the optical system at a focal length of 550 mm;

FIG. 5 is a diagram of the transfer function of the optical system at a focal length of 260 mm;

FIG. 6 is a diagram of the transfer function of the optical system at a focal length of 55 mm;

FIG. 7 is a diagram of a focal length of the optical system at 550 mm;

FIG. 8 is a diagram of the focal length of the optical system at 260 mm;

FIG. 9 is a diagram of a focal length of the optical system at 55 mm;

FIG. 10 is a graph showing the curvature of field and distortion at a focal length of 550mm for the optical system;

FIG. 11 is a graph showing the curvature of field and distortion when the focal length of the optical system is 260 mm;

FIG. 12 is a graph showing the curvature of field and distortion at a focal length of 55mm for the optical system;

FIG. 13 is a diagram showing the relationship between the phase period and the radial distance of the diffraction element of the optical system;

FIG. 14 is a schematic diagram of the movement traces of the zoom group and the compensation group of the optical system;

in the figure: 1. a first meniscus positive lens; 2. a first negative meniscus lens; 3. a second negative meniscus lens; 4. a third negative meniscus lens; 5. a second meniscus positive lens; 6. a fourth negative meniscus lens; 7. a biconvex positive lens; 8. a first planar mirror; 9. a second planar mirror; 10. a third meniscus positive lens; 11. a third plane mirror; 12. a fourth 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.

A miniaturized negative compensation type medium wave refrigeration infrared continuous zooming optical system is characterized in that: the system adopts negative group mechanical compensation, secondary 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; the variable power group comprises a first negative meniscus lens 2 and a second negative meniscus lens 3; the compensation group comprises a third negative meniscus lens 4; the rear fixed group comprises a second positive meniscus lens 5, a fourth negative meniscus lens 6, a double convex positive lens 7, a third positive meniscus lens 10 and a fourth 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 second image plane; in the zooming process, the zooming group and the compensation group move along the optical axis, the front fixed group, the rear fixed group and the infrared detector 13 keep in situ, and the distance between the first meniscus negative lens 2 and the second meniscus negative lens 3 of the zooming group keeps constant;

in the zooming process of the system, 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 9 and a third plane reflector 11 are arranged in the rear fixing group; the first plane reflector 8 and the second plane reflector 9 are adjacently arranged, and the first plane reflector 8 and the second plane reflector 9 are arranged between the double convex positive lens 7 and the third meniscus positive lens 10; the third plane mirror 11 is arranged between the third positive meniscus lens 10 and the fourth positive meniscus lens 12; the normal lines of the first plane reflector 8, the second plane reflector 9 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:

2.65f≤f1≤2.8f，-1.1f≤f2≤-0.9f，-1.9f≤f3≤-1.8f，：-1.65f≤f4≤-1.6f，0.95f≤f5≤1.1f，-1.95f≤f6≤-1.9f，1.3f≤f7≤1.35f，2.5f≤f8≤2.53f，0.2f≤f9≤0.3f；

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 first negative meniscus lens 2,

f3 is the effective focal length of the second negative meniscus lens 3,

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

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

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

f7 is the effective focal length of the biconvex positive lens 7,

f8 is the effective focal length of the third positive meniscus lens 10,

f9 is the effective focal length of the fourth positive meniscus lens 12;

the light incidence side surfaces of the first negative meniscus lens 2, the second positive meniscus lens 5 and the double convex positive lens 7 are all of even aspheric surface shapes;

the surface equation of the light incident side of the first meniscus negative lens 2 is as follows:

wherein: c. C₁Is the curvature of the light incident side surface of the first meniscus negative lens 2, r₁Is a radial coordinate, k, of the incident-side surface of the first negative meniscus lens 2 in a direction perpendicular to the optical axis₁Is a conic constant of the incident light side surface of the first negative meniscus lens 2, A₁Is a fourth-order aspheric coefficient of the incident light side surface of the first meniscus negative lens 2, B₁A sixth-order aspheric coefficient, C, of the incident-light-side surface of the first negative meniscus lens 2₁An eighth-order aspheric coefficient of the light incident side surface of the first negative meniscus lens 2;

the surface equation of the light incident side of the second meniscus positive lens 5 is as follows:

wherein: c. C₂A second meniscus positive lens) of the incident light side surface, r₂Is a radial coordinate, k, of the incident-side surface of the second meniscus positive lens 5 in the direction perpendicular to the optical axis₂Is a conic constant of the incident light side surface of the second meniscus positive lens 5, A₂Is a fourth-order aspheric coefficient of the light incident surface of the second meniscus positive lens 5, B₂A sixth-order aspheric coefficient, C, of the incident-light-side surface of the second meniscus positive lens 5₂An eighth-order aspheric coefficient of the light incident side surface of the second meniscus positive lens 5;

the surface equation of the light incident side of the biconvex positive lens 7 is as follows:

wherein: c. C₃The curvature of the light incident side surface of the biconvex positive lens 7, r₃Is a radial coordinate, k, of the light-incident side surface of the biconvex positive lens 7 perpendicular to the optical axis direction₃Is a conic constant of the incident-side surface of the biconvex positive lens 7, A₃Fourth order aspherical surface coefficient B of the light incident side surface of the biconvex positive lens 7₃A sixth-order aspherical surface coefficient, C, of the light incident surface side of the biconvex positive lens 7₃An eighth order aspherical surface coefficient of the light incident side surface of the biconvex positive lens 7;

the surface of the light emitting side of the fourth positive meniscus lens 12 adopts a diffractive aspheric surface, the aspheric surface and the diffractive surface act on the same lens surface, and the surface equation is as follows:

wherein, c₅Is the curvature of the light-incident-side surface of the fourth meniscus positive lens 12, r₅Is a radial coordinate, k, of the light-emitting side surface of the fourth meniscus positive lens 12 in the direction perpendicular to the optical axis₅Is a conic constant of the light-exit side surface of the fourth meniscus positive lens 12, A₅Is a fourth-order aspheric coefficient, B, of the light-emitting side surface of the fourth meniscus positive lens 12₅A sixth-order aspheric coefficient, C, of the light-emitting side surface of the fourth meniscus positive lens 12₅Is in a fourth meniscus shapeAn eighth order aspherical surface coefficient of the light exit side surface of the positive lens 12; HOR is the diffraction order of the light-emitting side surface of the fourth meniscus positive lens 12, C₁、C₂Is the diffraction coefficient of the light-emitting side surface of the fourth positive meniscus lens 12, n is the refractive index of the optical material of the fourth positive meniscus lens 12, n₀Is the refractive index of air, λ₀Designing a center wavelength for the optical system;

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 fourth meniscus positive lens 12 of the fixed group and the infrared detector 13.

Based on the technical characteristics of the miniaturized negative compensation type 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, the design rule of each lens surface type and the like, the following preferred specific 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: 4; focal length: 55 mm-550 mm; the medium wave refrigeration detector is matched with the medium wave refrigeration detector with 640 multiplied by 512 and the pixel size of 15 mu m; the overall size of the system is as follows: 208mm × 176mm × 155mm (length × width × height);

table 1 lists detailed data of embodiments of optical systems according to the invention at focal lengths of 55mm to 550mm, including face type, radius of curvature, thickness, caliber, material of each lens; wherein the unit of curvature radius, thickness and caliber of the lens is mm;

TABLE 1

Table 2 lists aspheric coefficients of the light-incident-side surface of the first negative meniscus lens 2 according to the invention;

TABLE 2

Table 3 lists aspherical coefficients of the light-incident-side surface of the second positive meniscus lens 5 according to the present invention;

TABLE 3

Table 4 lists the aspherical coefficients of the light-incident-side surface of the biconvex positive lens 7 according to the invention;

TABLE 4

Table 5 lists the diffractive aspheric coefficients of the light exit side of the fourth meniscus positive lens 12 according to the invention;

TABLE 5

When the miniaturized negative compensation type 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 first negative meniscus lens 2, is diverged by the first negative meniscus lens 2 to reach the second negative meniscus lens 3, is diverged by the second negative meniscus lens 3 to reach the third negative meniscus lens 4, is diverged by the third negative meniscus lens 4 to reach the second positive meniscus lens 5, is converged by the second positive meniscus lens 5 to reach the fourth negative meniscus lens 6, is diverged by the fourth negative meniscus lens 6 to reach the double convex positive lens 7, is converged by the double convex positive lens 7 to reach the first plane reflector 8, is reflected by the first plane reflector 8 to reach the second plane reflector 9, is reflected by the second plane reflector 9 to reach the third positive meniscus lens 10, is converged by the third positive meniscus lens 10 to reach the third plane reflector 11, is reflected by the third plane reflector 11 to reach the fourth positive meniscus lens 12, the image is focused by the fourth meniscus positive lens 12 and then is imaged on the infrared detector 13.

When the miniaturized negative compensation type 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 and the compensation group are positioned in the middle of the front fixed group and the rear fixed group; in the process of changing from short focus to long focus, the zoom group and the compensation group are mutually opposite and close together on the optical axis and then move to the image space together; 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.