An ultra-long focal length dual optical path lens

Abstract

The present application relates to a kind of super long focus double optical path lenses, and the optical structure of lens is composed of common optical path, light splitting element, mid-wave infrared imaging lens group and long-wave infrared imaging lens group, and the optical path system of mid-wave is sequentially provided with flat concave mirror A1, flat convex mirror A2, meniscus positive lens A3, meniscus negative lens A4, meniscus negative lens A5, light splitting element, meniscus positive lens C1, meniscus positive lens C2, meniscus negative lens C3, meniscus positive lens C4 from object side to image side along its optical axis direction;The optical path system of long-wave is sequentially provided with common optical path, light splitting element, meniscus positive lens D1, mirror D2, meniscus positive lens D3, meniscus negative lens D4, meniscus positive lens D5 from object side to image side along its optical axis direction, and double-band common optical path optical system meets mid-wave infrared, long-wave infrared double-band common aperture design, and after being split, each waveband is respectively clearly imaged, each waveband reaches the limit frequency of respective sensor, realizes the miniaturization of entire optical system, and is stable and reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of super long focal length dual optical path lenses. BACKGROUND

[0002] With the development of camouflage technology, the difficulty of detecting and identifying targets is increasing, and single-band detection has been difficult to meet various needs. The optical characteristics of targets in different spectral bands are quite different, such as the long-wave infrared effect of ground feature contour at room temperature is clear, and the infrared warning is usually used to view the target heat source in the middle-wave infrared. Multi-band infrared optical systems can obtain sufficient useful information and effectively identify target objects from a large number of images, and can play a decisive role in military operations.

[0003] To realize multi-band image fusion, different waveband imaging systems can be independent or common aperture. Common aperture means that different waveband optical systems share part of the optical path structure, which has high fusion degree, small overall space structure, and can better meet the requirements of different precision guidance systems. Among them, the shared part of the optical path can be transmissive or reflective. Since it is difficult to obtain large-aperture, high-quality infrared lens materials, the types of infrared lens materials are few and the wide-band chromatic aberration is not easy to eliminate, so the transmissive common aperture is not suitable for long focal length systems. The reflective common aperture system does not produce chromatic aberration in the reflection part, can achieve wide-spectrum design, and can achieve long focal length and large aperture. SUMMARY

[0004] In view of the shortcomings of the prior art, to ensure that the infrared search and track system can search and track targets at ultra-long distances, and meet the requirements of small size and light weight, a super long focal length dual optical path lens is proposed. The focal length of the middle-wave optical path system in the lens is greater than or equal to 2m, and the focal length of the long-wave optical path system is greater than or equal to 1m, which can search and track targets at ultra-long distances. The primary and secondary mirrors of the system reflection part are made of quartz glass, and the imaging part is designed by combining conventional infrared materials. The dual-band common optical path optical system meets the design of common aperture of middle-wave infrared and long-wave infrared, and the dual-band light is matched with a cooled middle-wave infrared detector and a cooled long-wave detector after being split. Each waveband reaches the limit frequency of the respective sensor, clear imaging, and realizes the miniaturization of the entire optical system.

[0005] In order to solve the above technical problems, the technical scheme of the present application is: the optical structure of the lens is composed of a common light path, a light splitting element, a mid-wave infrared imaging lens group and a long-wave infrared imaging lens group; a mid-wave light path system composed of the common light path, the light splitting element and the mid-wave infrared imaging lens group is sequentially provided with a plano-concave primary mirror A1, a plano-convex secondary mirror A2, a meniscus positive lens A3, a meniscus negative lens A4, a meniscus negative lens A5, the light splitting element, a meniscus positive lens C1, a meniscus positive lens C2, a meniscus negative lens C3 and a meniscus positive lens C4 along the optical axis direction from the object side to the image side; a long-wave light path system composed of the common light path, the light splitting element and the long-wave infrared imaging lens group is sequentially provided with the plano-concave primary mirror A1, the plano-convex secondary mirror A2, the meniscus positive lens A3, the meniscus negative lens A4, the meniscus negative lens A5, the light splitting element, a meniscus positive lens D1, a reflecting mirror D2, a meniscus positive lens D3, a meniscus negative lens D4 and a meniscus positive lens D5 along the optical axis direction from the object side to the image side.

[0006] Further, in the mid-wave light path system, the concave surfaces of the plano-concave primary mirror A1, the meniscus positive lens A3 and the meniscus positive lens D3 all face the object plane, the concave surface of the meniscus positive lens D1 faces a vertical plane of the object plane, the convex surface of the plano-convex secondary mirror A2 faces the image plane, and the convex surfaces of the meniscus negative lens A4, the meniscus negative lens A5, the meniscus negative lens D4 and the meniscus positive lens D5 all face the object plane.

[0007] Further, in the long-wave light path system, the concave surfaces of the plano-concave primary mirror A1, the meniscus positive lens A3, the meniscus positive lens C1 and the meniscus positive lens C2 all face the object plane, the convex surface of the plano-convex secondary mirror A2 faces the image plane, and the convex surfaces of the meniscus negative lens A4, the meniscus negative lens A5, the meniscus negative lens C3 and the meniscus positive lens C4 all face the object plane.

[0008] Further, in the mid-wave light path system, the air gap from left to right is as follows: the air gap between the plano-concave primary mirror A1 and the plano-convex secondary mirror A2 is 133.23 mm, the air gap between the plano-convex secondary mirror A2 and the meniscus positive lens A3 is 198.76 mm, the air gap between the meniscus positive lens A3 and the meniscus negative lens A4 is 1.4 mm, the air gap between the meniscus negative lens A4 and the meniscus negative lens A5 is 1.0 mm, the air gap between the meniscus negative lens A5 and the light splitting element B is 22.95 mm, the air gap between the light splitting element B and the meniscus positive lens C1 is 100 mm, the air gap between the meniscus positive lens C1 and the meniscus positive lens C2 is 35.58 mm, the air gap between the meniscus positive lens C2 and the meniscus negative lens C3 is 2.90 mm, and the air gap between the meniscus negative lens C3 and the meniscus positive lens C4 is 1.35 mm.

[0009] Further, in the long-wave optical path system, the spacings from left to right are as follows: the air spacing between the plano-concave primary mirror A1 and the plano-convex secondary mirror A2 is 133.23 mm, the air spacing between the plano-convex secondary mirror A2 and the meniscus positive lens A3 is 198.76 mm, the air spacing between the meniscus positive lens A3 and the meniscus negative lens A4 is 1.4 mm, the air spacing between the meniscus negative lens A4 and the meniscus negative lens A5 is 1.0 mm, the air spacing between the meniscus negative lens A5 and the beam-splitting element B is 22.95 mm, the air spacing between the beam-splitting element B and the meniscus positive lens D1 is 92.17 mm, the air spacing between the meniscus positive lens D1 and the mirror D2 is 25.41 mm, the air spacing between the mirror D2 and the meniscus positive lens D3 is 48.97 mm, the air spacing between the meniscus positive lens D3 and the meniscus negative lens D4 is 2.91 mm, and the air spacing between the meniscus negative lens D4 and the meniscus positive lens D5 is 3.83 mm.

[0010] Further, the specific performance parameters of the optical structure are as follows:

[0011] (1) working spectral range: 3.7-4.8 um, 7.7-10.5 um;

[0012] (2) F number: 4.0 / 2.0;

[0013] (3) adapted detector: a refrigeration type mid-wave infrared detector 640x512@15 um;

[0014] a refrigeration type long-wave infrared detector 640x512@15 um.

[0015] Further, let the total focal length of the mid-wave be f, the total focal length of the long-wave be f', the optical lens focal lengths of the mid-wave optical path imaging part from the object plane to the image plane are f1-f2-f3-f4-f5-f6-f7 in turn, and the optical lens focal lengths of the long-wave optical path imaging part from the object plane to the image plane are f8-f9-f10-f11-f12-f13-f14 in turn, which have the following relationships:

[0016] -1 < f1 / f < 0; 0 < f2 / f < 2; 0 < f3 / f < 2;

[0017] -1 < f4 / f < 0; -1 < f5 / f < 0; 0 < f6 / f < 2; -1 < f7 / f < 0;

[0018] -1 < f8 / f' < 0; 0 < f9 / f' < 2; 0 < f10 / f' < 2;

[0019] -1 < f11 / f' < 0; -1 < f12 / f' < 0; -1 < f13 / f' < 2; -1 < f14 / f' < 2.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] a) Dual-band common optical path optical system meets the design of common aperture of middle wave infrared and long wave infrared, and after dual-band splitting, clear images are formed respectively, each waveband reaches the limit frequency of the respective sensor, and the miniaturization of the entire optical system is realized. The target information of two wavebands can be captured simultaneously, the detection and identification performance of the target is improved in a complex background environment, more comprehensive and accurate target information is obtained, and the false alarm rate is reduced.

[0022] b) The focal length of the middle wave optical path system is greater than or equal to 2m, and the focal length of the long wave optical path system is greater than or equal to 1m, and the super long focal length can search and track targets at a super long distance.

[0023] c) The catadioptric structure form is adopted, the primary and secondary mirrors of the reflection part adopt quartz glass, and the transmission part adopts a combination of conventional infrared materials, the process of the entire optical system is good, easy to process, and low in cost.

[0024] d) The optical system adopts a secondary imaging structure form, realizes 100% cold stop efficiency, effectively compresses the overall radial size of the optical system, and realizes the miniaturization of the optical system.

[0025] e) The system works in the waveband of 3.7um-4.8um and 7.7um-10.5um, covers a wide waveband range, and the front lens of the full-transmission system has a large chromatic aberration. The system adopts a catadioptric system, the reflection part of the front group does not produce chromatic aberration, is easy to realize large aperture, and the catadioptric system has good heat resistance and simple structure.

[0026] The application will be further described in detail in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 It is an optical structure diagram of the embodiment of the application;

[0028] Fig. 2 It is an MTF curve diagram of the middle wave optical path system in the embodiment of the application;

[0029] Fig. 3 It is an MTF curve diagram of the long wave optical path system in the embodiment of the application;

[0030] Fig. 4 It is a distortion diagram of the middle wave optical path system in the embodiment of the application;

[0031] Fig. 5 It is a distortion diagram of the long wave optical path system in the embodiment of the application.

[0032] In the figure: A-common optical path, C-mid-wave infrared imaging lens group, D-long-wave infrared imaging lens group, A1-flat concave primary mirror A1, A2-flat convex secondary mirror A2, A3-crescent positive lens A3, A4-crescent negative lens A4, A5-crescent negative lens A5, B-diffractive element, C1-crescent positive lens C1, C2-crescent positive lens C2, C3-crescent negative lens C3, C4-crescent positive lens C4, D1-crescent positive lens D1, D2-mirror D2, D3-crescent positive lens D3, D4-crescent negative lens D4, D5-crescent positive lens D5. DETAILED DESCRIPTION

[0033] In order to make the above features and advantages of the present application more obvious and easy to understand, the following specific examples are described in detail below with reference to the accompanying drawings.

[0034] For a transmissive refrigeration type mid-long wave infrared common aperture system, the first piece of material is usually silicon. When the focal length of the system is greater than 2m, in order to meet the 100% cold stop efficiency, the optical system exit pupil and the detector cold stop need to be matched, a secondary imaging structure type is adopted, and the radial size of the first piece of the system is greater than 500mm. It is a difficult problem to manufacture such a large aperture of silicon material or surface machining.

[0035] The present application adopts a catadioptric structure type, the primary and secondary mirrors of the reflection part are made of quartz glass, and the transmission part is made of a conventional infrared material combination. The aperture of the transmission part lens is small and easy to process. In the design optimization process, the optical power of each lens is reasonably distributed, and the use of even aspheric surfaces is combined to balance the system aberration, so that the overall volume of the optical system is small enough. The sensitivity of each optical part is reduced by adjusting the curvature and thickness, so that the lens is easier to process and adjust.

[0036] The design scheme of the lens is as follows:

[0037] As shown in Figs. 1-5 A super-long focal length dual optical path lens, the optical structure of the lens is composed of a common optical path A, a diffractive element B, a mid-wave infrared imaging lens group C and a long-wave infrared imaging lens group D. Two independent detectors receive optical energy information of the optical system and convert it into electrical signals to output target images.

[0038] The middle wave light path system is sequentially provided with a common light path A, a light splitting element B and a middle wave infrared imaging part C from an object plane to an image plane; wherein, the flat concave primary mirror A1 is concave to the object plane and is made of quartz glass; the flat convex secondary mirror A2 is convex to the image plane and is made of quartz glass; the concave meniscus positive lens A3 is concave to the object plane and is made of germanium single crystal; the convex meniscus negative lens A4 is convex to the object plane and is made of zinc selenide; the convex meniscus negative lens A5 is convex to the object plane and is made of germanium single crystal; the light splitting element B is made of silicon single crystal; the concave meniscus positive lens C1 is concave to the object plane and is made of silicon single crystal; the concave meniscus positive lens C2 is concave to the object plane and is made of silicon single crystal; the convex meniscus negative lens C3 is convex to the object plane and is made of germanium single crystal; and the convex meniscus positive lens C4 is convex to the object plane and is made of silicon single crystal.

[0039] The long wave light path system is sequentially provided with a common light path A, a light splitting element B and a long wave infrared imaging part D from an object plane to an image plane; wherein, the flat concave primary mirror A1 is concave to the object plane and is made of quartz glass; the flat convex secondary mirror A2 is convex to the image plane and is made of quartz glass; the concave meniscus positive lens A3 is concave to the object plane and is made of germanium single crystal; the convex meniscus negative lens A4 is convex to the object plane and is made of zinc selenide; the convex meniscus negative lens A5 is convex to the object plane and is made of germanium single crystal; the light splitting element B is made of silicon single crystal; the concave meniscus positive lens D1 is concave to the object plane and is made of germanium single crystal; the reflecting mirror D2 is made of quartz glass; the concave meniscus positive lens D3 is concave to the object plane and is made of chalcogenide glass; the convex meniscus negative lens D4 is convex to the object plane and is made of zinc selenide; and the convex meniscus positive lens D5 is convex to the object plane and is made of germanium single crystal; the concave meniscus positive lens D3, the convex meniscus negative lens D4 and the convex meniscus positive lens D5 are all arranged in parallel with the middle wave infrared imaging lens group in the middle wave light path system and are reflected by the reflecting mirror D2 to be imaged on the image plane end of the long wave infrared imaging lens group.

[0040] In the embodiment of the present application, the specific performance parameters of the optical structure are as follows:

[0041] (1) working spectral range: 3.7um~4.8um, 7.7um~10.5um;

[0042] (2) F number: 4.0 / 2.0;

[0043] (3) adaptive detector: refrigeration type middle wave infrared detector 640x512@15um;

[0044] Refrigeration type long wave infrared detector 640x512@15um.

[0045] In the embodiment of the present application, the spacing of the middle wave optical path structure from left to right is as follows: the air gap between the primary mirror A1 and the secondary mirror A2 is 133.23 mm, the air gap between the secondary mirror A2 and the meniscus positive lens A3 is 198.76 mm, the air gap between the meniscus positive lens A3 and the meniscus negative lens A4 is 1.4 mm, the air gap between the meniscus negative lens A4 and the meniscus negative lens A5 is 1.0 mm, the air gap between the meniscus negative lens A5 and the beam splitter B is 22.95 mm, the air gap between the beam splitter B and the meniscus positive lens C1 is 100 mm, the air gap between the meniscus positive lens C1 and the meniscus positive lens C2 is 35.58 mm, the air gap between the meniscus positive lens C2 and the meniscus negative lens C3 is 2.90 mm, and the air gap between the meniscus negative lens C3 and the meniscus positive lens C4 is 1.35 mm.

[0046] In the embodiment of the present application, the spacing of the long wave optical path structure from left to right is as follows: the air gap between the primary mirror A1 and the secondary mirror A2 is 133.23 mm, the air gap between the secondary mirror A2 and the meniscus positive lens A3 is 198.76 mm, the air gap between the meniscus positive lens A3 and the meniscus negative lens A4 is 1.4 mm, the air gap between the meniscus negative lens A4 and the meniscus negative lens A5 is 1.0 mm, the air gap between the meniscus negative lens A5 and the beam splitter B is 22.95 mm, the air gap between the beam splitter B and the meniscus positive lens D1 is 92.17 mm, the air gap between the meniscus positive lens D1 and the mirror D2 is 25.41 mm, the air gap between the mirror D2 and the meniscus positive lens D3 is 48.97 mm, the air gap between the meniscus positive lens D3 and the meniscus negative lens D4 is 2.91 mm, and the air gap between the meniscus negative lens D4 and the meniscus positive lens D5 is 3.83 mm.

[0047] In the embodiment of the present application, the system optical element is characterized in that: the total focal length of the middle wave is f, the total focal length of the long wave is f', the optical lens focal lengths of the middle wave optical path imaging part from the object plane to the image plane are f1-f2-f3-f4-f5-f6-f7 in turn, and the optical lens focal lengths of the long wave optical path imaging part from the object plane to the image plane are f8-f9-f10-f11-f12-f13-f14 in turn, which have the following relationships:

[0048] -1 < f1 / f < 0; 0 < f2 / f < 2; 0 < f3 / f < 2;

[0049] -1 < f4 / f < 0; -1 < f5 / f < 0; 0 < f6 / f < 2; -1 < f7 / f < 0;

[0050] -1 < f8 / f' < 0; 0 < f9 / f' < 2; 0 < f10 / f' < 2;

[0051] -1 < f11 / f' < 0; -1 < f12 / f' < 0; -1 < f13 / f' < 2; -1 < f14 / f' < 2.

[0052] The present application adopts catadioptric secondary imaging structure form, the main and secondary mirrors of the reflection part adopt quartz glass, the transmission part adopts conventional infrared material combination, the imaging part mirror aperture is small, and is easy to process. In the design optimization process, the optical power of each lens is reasonably distributed, and the even aspheric surface is used to balance the system aberration, so that the overall volume of the optical system is small enough. The sensitivity of each optical element is reduced by adjusting the curvature and thickness, so that the lens is more easy to process and adjust.

[0053] The data in the following table is the optical parameter of the embodiment of the present application.

[0054] Table One: Optical element parameter table of the middle wave optical path

[0055]

[0056]

[0057] Table Two: Optical element parameter table of the long wave optical path

[0058]

[0059] Table Three: Long wave optical path system aspherical surface related data

[0060]

[0061] Table Four: Middle wave optical path system aspherical surface related data

[0062]

[0063]

[0064] The aspherical surface expression is:

[0065]

[0066] Z represents the position in the direction of the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the curvature radius, k represents the conic coefficient, α4, α6, α8, α 10 ... represents the aspherical surface coefficient. In the aspherical surface data, E-n represents "×10 -n ", for example, 1.4248E-11 represents 1.4248×10 -11 .

[0067] The present application is not limited to the above best mode, anyone can draw other various forms of super-long focal length dual optical path lens and its working method under the inspiration of the present application. Any equivalent changes and modifications made in the scope of the present application shall be covered by the present application.

Claims

1. An ultra-telephoto dual optical path lens, characterized in that: The optical structure of the lens is composed of a common light path, a light splitting element, a mid-wave infrared imaging lens group and a long-wave infrared imaging lens group, a mid-wave light path system composed of the common light path, the light splitting element and the mid-wave infrared imaging lens group is sequentially provided with a plano-concave primary mirror A1, a plano-convex secondary mirror A2, a meniscus positive lens A3, a meniscus negative lens A4, a meniscus negative lens A5, the light splitting element, a meniscus positive lens C1, a meniscus positive lens C2 and a meniscus negative lens C3 along the optical axis direction from the object side to the image side, and a long-wave light path system composed of the common light path, the light splitting element and the long-wave infrared imaging lens group is sequentially provided with the plano-concave primary mirror A1, the plano-convex secondary mirror A2, the meniscus positive lens A3, the meniscus negative lens A4, the meniscus negative lens A5, the light splitting element, a meniscus positive lens D1, a reflecting mirror D2, a meniscus positive lens D3, a meniscus negative lens D4 and a meniscus positive lens D5 along the optical axis direction from the object side to the image side. In the mid-wave light path system, the concave surfaces of the plano-concave primary mirror A1, the meniscus positive lens A3 and the meniscus positive lens D3 all face the object plane, the concave surface of the meniscus positive lens D1 faces a vertical plane of the object plane, the convex surface of the plano-convex secondary mirror A2 faces the image plane, and the convex surfaces of the meniscus negative lens A4, the meniscus negative lens A5, the meniscus negative lens D4 and the meniscus positive lens D5 all face the object plane. In the long-wave light path system, the concave surfaces of the plano-concave primary mirror A1, the meniscus positive lens A3, the meniscus positive lens C1 and the meniscus positive lens C2 all face the object plane, the convex surface of the plano-convex secondary mirror A2 faces the image plane, and the convex surfaces of the meniscus negative lens A4, the meniscus negative lens A5, the meniscus negative lens C3 and the meniscus positive lens C4 all face the object plane. Let the total focal length of the mid-wave be f, the total focal length of the long-wave be f´, the optical lens focal lengths of the mid-wave light path imaging part from the object plane to the image plane be f1-f2-f3-f4-f5-f6-f7 in turn, and the optical lens focal lengths of the long-wave light path imaging part from the object plane to the image plane be f8-f9-f10-f11-f12-f13-f14 in turn, and they have the following relationships: -1 < f1 / f < 0; 0 < f2 / f < 2; 0 < f3 / f < 2; -1 < f4 / f < 0; -1 < f5 / f < 0; 0 < f6 / f < 2; -1 < f7 / f < 0; -1 < f8 / f´ < 0; 0 < f9 / f´ < 2; 0 < f10 / f´ < 2; -1 < f11 / f´ < 0; -1 < f12 / f´ < 0; -1 < f13 / f´ < 2; -1 < f14 / f´ < 2.

2. The ultra-long focal length dual optical path lens according to claim 1, characterized in that: In the middle wave optical path system, the interval from left to right is as follows: the air interval of the plano-concave primary mirror A1 and the plano-convex secondary mirror A2 is 133.23mm, the air interval of the plano-convex secondary mirror A2 and the meniscus positive lens A3 is 198.76mm, the air interval of the meniscus positive lens A3 and the meniscus negative lens A4 is 1.4mm, the air interval of the meniscus negative lens A4 and the meniscus negative lens A5 is 1.0mm, the air interval of the meniscus negative lens A5 and the beam splitting element B is 22.95mm, the air interval of the beam splitting element B and the meniscus positive lens C1 is 100mm, the air interval of the meniscus positive lens C1 and the meniscus positive lens C2 is 35.58mm, the air interval of the meniscus positive lens C2 and the meniscus negative lens C3 is 2.90mm, and the air interval of the meniscus negative lens C3 and the meniscus positive lens C4 is 1.35mm.

3. The ultra-long focal length dual optical path lens according to claim 1, characterized in that: In the long wave optical path system, the interval from left to right is as follows: the air interval of the plano-concave primary mirror A1 and the plano-convex secondary mirror A2 is 133.23mm, the air interval of the plano-convex secondary mirror A2 and the meniscus positive lens A3 is 198.76mm, the air interval of the meniscus positive lens A3 and the meniscus negative lens A4 is 1.4mm, the air interval of the meniscus negative lens A4 and the meniscus negative lens A5 is 1.0mm, the air interval of the meniscus negative lens A5 and the beam splitting element B is 22.95mm, the air interval of the beam splitting element B and the meniscus positive lens D1 is 92.17mm, the air interval of the meniscus positive lens D1 and the mirror D2 is 25.41mm, the air interval of the mirror D2 and the meniscus positive lens D3 is 48.97mm, the air interval of the meniscus positive lens D3 and the meniscus negative lens D4 is 2.91mm, and the air interval of the meniscus negative lens D4 and the meniscus positive lens D5 is 3.83mm.

4. The ultra-long focal length dual optical path lens according to claim 1, characterized in that: The specific performance parameters of the optical structure are as follows: (1) working spectral range: 3.7um~4.8um, 7.7um~10.5um; (2) F number: 4.0 / 2.0; Adapted detector: cooled middle wave infrared detector 640×512@15um; Cooled long wave infrared detector 640×512@15um.

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