Large-overload large-aperture infrared lens system

Abstract

The invention relates to a large-overload large-aperture infrared lens system which is characterized in that a lens is composed of six lenses which are sequentially provided with a meniscus positive lens A, a meniscus negative lens B, a meniscus positive lens C, a meniscus negative lens D, a meniscus positive lens D and a meniscus negative lens E from an object plane to an image plane from the object plane to the image plane, the convex surface of the meniscus positive lens B faces the object surface and is made of zinc sulfide; the convex surface of the meniscus negative lens C faces the object plane, and the meniscus negative lens C is made of germanium single crystal; the biconvex positive lens D is made of chalcogenide glass; the convex surface of the meniscus positive lens E faces the object plane, and the meniscus positive lens E is made of chalcogenide glass; the convex surface of the meniscus positive lens F faces the object plane, and the meniscus positive lens F is made of chalcogenide glass; the working wave band of the lens ranges from 8 microns to 14 microns, and the lens has a large clear aperture, can receive more target signal energy, is large in system target surface and large in view field, and can search a target in a larger range.

Description

Technical field:

[0001] The invention relates to an infrared lens, in particular to a large-overload and large-aperture infrared lens system. Background technology:

[0002] When the focal length of an optical system is constant, the larger the aperture, the more energy it receives and the stronger its detection capability for small targets, that is, the higher the detection sensitivity of the system. However, the F number of currently uncooled long-wave infrared lenses is usually 1.0, and there are very few uncooled long-wave infrared lenses with an F number ≤0.8.

[0003] In addition, the long-wave transmission lens is used in an environment with strong vibrations, and has high requirements on the lens strength and structural strength of the lens. Once the strength does not meet the use requirements, it is easy to cause product damage or a decline in imaging quality. Summary of the invention:

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a large-overload large-aperture infrared lens system, which has an operating band between 8um and 14um, a large clear aperture, can receive more target signal energy, a large target surface and a large field of view, and can search for targets in a wider range.

[0005] The technical solution of the present invention is a large overload large aperture infrared lens system, characterized in that: the lens is composed of six lenses, which are arranged in sequence from the object plane to the image plane: a positive meniscus lens A with a convex surface facing the object plane, made of germanium single crystal; a positive meniscus lens B with a convex surface facing the object plane, made of zinc sulfide; a negative meniscus lens C with a convex surface facing the object plane, made of germanium single crystal; a double convex positive lens D, made of chalcogenide glass; a positive meniscus lens E with a convex surface facing the object plane, made of chalcogenide glass; a positive meniscus lens F with a convex surface facing the object plane, made of chalcogenide glass;

[0006] The specific performance parameters of this lens system are: (1) Working spectrum range: 8um~12um;

[0007] (2) F number: ≤0.8; (3) Target surface: Φ≥20mm; (4) Distortion: ≤1%;

[0008] The total focal length of the lens system is f, and the focal lengths of the lenses from the object plane to the image plane are f1, f2, f3, f4, f5, and f6, respectively. The relationship between each lens and the total focal length is as follows: 50 <f1 / f<100;5<f2 / f<10;-5<f3 / f<0;0<f4 / f<5;0<f5 / f<5;0<f6 / f<5。

[0009] Further, the parameter table of the above lenses:

[0010]

[0011] Aspherical lens related data:

[0012]

[0013]

[0014] The aspheric expression is:

[0015]

[0016] Z represents the position along the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, k represents the cone coefficient, α4, α6, α8, α 10 ... represents the aspheric coefficient. In aspheric data, En represents “×10 -n ", for example, -1.56E-07 represents -1.56×10 -7 .

[0017] Furthermore, the above-mentioned meniscus positive lens A and meniscus positive lens B are installed at the front end of the main lens barrel and locked by a front pressure ring, and a first spacer ring is provided between the meniscus positive lens A and the meniscus positive lens B for setting an air gap between the two; the meniscus negative lens C, the biconvex positive lens D, the meniscus positive lens E, and the meniscus positive lens F are installed at the rear end of the main lens barrel and locked by a rear pressure ring, and the meniscus negative lens C, the biconvex positive lens D, the meniscus positive lens E, and the meniscus positive lens F are provided with corresponding second spacers, third spacers, fourth spacers, and fifth spacers between each other, and the air gap between each lens is controlled by controlling each spacer ring.

[0018] The present invention is composed of six lenses, adopts a refractive / diffractive hybrid optical system composed of four infrared materials, and combines the use of aspheric correction system aberrations; and the lens has an operating band between 8um and 14um, a large aperture, can achieve high energy concentration, high response sensitivity, strong detection capability for weak and small targets, and can receive more target signal energy. Description of the drawings:

[0019] Figure 1 is an optical structure diagram of the present invention;

[0020] Figure 2 It is a schematic diagram of the lens assembly structure of the present invention;

[0021] Figure 3 is the MTF value (20°C) of the lens system of the present invention;

[0022] Figure 4 is the MTF value of the lens system of the present invention (-40°C);

[0023] Figure 5is the MTF value (+60°C) of the lens system of the present invention;

[0024] Figure 6 is a distortion diagram of the lens system of the present invention;

[0025] Figure 7 It is a relative illumination curve diagram of the lens system of the present invention. Specific implementation method:

[0026] The technical solution of the present invention is: a large overload large aperture infrared lens system, the lens is composed of six lenses, which are arranged in sequence from the object plane to the image plane: a positive meniscus lens A with a convex surface facing the object plane, the material of which is a germanium single crystal; a positive meniscus lens B with a convex surface facing the object plane, the material of which is zinc sulfide; a negative meniscus lens C with a convex surface facing the object plane, the material of which is a germanium single crystal; a double convex positive lens D, the material of which is chalcogenide glass; a positive meniscus lens E with a convex surface facing the object plane, the material of which is chalcogenide glass; a positive meniscus lens F with a convex surface facing the object plane, the material of which is chalcogenide glass;

[0027] The specific performance parameters of this lens system are: (1) Working spectrum range: 8um~12um;

[0028] (3) F number: ≤0.8; (3) Target surface: Φ≥20mm; (4) Distortion: ≤1%;

[0029] The total focal length of the lens system is f, and the focal lengths of the lenses from the object plane to the image plane are f1, f2, f3, f4, f5, and f6, respectively. The relationship between each lens and the total focal length is as follows: 50 <f1 / f<100;5<f2 / f<10;-5<f3 / f<0;0<f4 / f<5;0<f5 / f<5;0<f6 / f<5。

[0030] Compared with other lenses, this lens has the following advantages:

[0031] a) The present invention has a large clear aperture, can collect more target signal energy, has strong detection capability for weak targets, and has higher detection sensitivity;

[0032] b) The present invention adopts a hybrid refractive / diffractive structure, and the system can achieve achromatic and thermal difference effects while using less material, reducing the volume of the system while achieving normal imaging in high and low temperature environments;

[0033] c) The lens has good vibration and shock resistance, which solves the problem that the subsequent physical measures of traditional small fixed-focus lenses cannot achieve the expected environmental adaptability due to their small size and compact structure;

[0034] The present invention adopts a refractive optical structure, does not need to adjust the reflector, and is easy to assemble.

[0035] Parameter table of the above lenses:

[0036]

[0037] Aspherical lens related data:

[0038] <![CDATA[α4]]> <![CDATA[α6]]> <![CDATA[α8]]> <![CDATA[α 10 ]]> Diffraction surface S2 -2.49E-07 3.13E-10 7.87E-13 -1.27E-15 Aspherical S4 7.08E-06 -1.77E-10 -6.07E-12 2.90E-14 Diffraction surface S6 -3.89E-06 3.34E-09 -1.08E-11 7.90E-15 Aspherical S7 5.66E-06 -1.69E-08 1.93E-11 -2.75E-14 Aspherical S8 -2.56E-06 -1.12E-08 1.46E-11 -1.29E-14 Diffraction surface S9 -4.80E-06 -2.33E-09 -8.37E-13 -1.51E-14 Aspherical S11 -1.45E-05 -1.67E-09 -1.71E-10 7.37E-13

[0039] The aspheric expression is:

[0040]

[0041] Z represents the position along the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, k represents the cone coefficient, α4, α6, α8, α 10 ... represents the aspheric coefficient. In aspheric data, En represents “×10 -n ", for example, -1.56E-07 represents -1.56×10 -7 .

[0042] Depend on Figure 3-5 It can be seen that the MTF curve of the lens is close to the diffraction limit, and the full field of view is greater than 0.35 at 42lp / mm, which has a high resolution. Figure 6 It can be seen that the distortion of this lens is less than 1.0%; Figure 7 It can be seen that the edge relative illumination of the system is greater than 80%, and the system image plane illumination is relatively uniform.

[0043] The meniscus positive lens A and the meniscus positive lens B are mounted at the front end of the main lens barrel 73 and are locked by a front pressure ring 71. A first spacer ring 72 is provided between the meniscus positive lens A and the meniscus positive lens B to set an air gap between the two.

[0044] The meniscus negative lens C, biconvex positive lens D, meniscus positive lens E, and meniscus positive lens F are installed at the rear end of the main lens barrel 73 and locked by a rear pressure ring 78. The meniscus negative lens C, biconvex positive lens D, meniscus positive lens E, and meniscus positive lens F are provided with corresponding second spacers 74, third spacers 75, fourth spacers 76, and fifth spacers 77 between each other, and the air gaps between the lenses are controlled by controlling each spacer.

[0045] The present invention is composed of six lenses, adopts a refractive / diffractive hybrid optical system composed of four infrared materials, and combines the use of aspheric correction system aberrations; and the lens has an operating band between 8um and 14um, a large aperture, can achieve high energy concentration, high response sensitivity, strong detection capability for weak and small targets, and can receive more target signal energy.

Claims

1. A large overload large aperture infrared lens system, characterized in that: The lens is composed of six lenses, which are arranged in order from the object plane to the image plane: a positive meniscus lens A with a convex surface facing the object plane, made of germanium single crystal; a positive meniscus lens B with a convex surface facing the object plane, made of zinc sulfide; a negative meniscus lens C with a convex surface facing the object plane, made of germanium single crystal; a double convex positive lens D, made of chalcogenide glass; a positive meniscus lens E with a convex surface facing the object plane, made of chalcogenide glass; and a positive meniscus lens F with a convex surface facing the object plane, made of chalcogenide glass. The specific performance parameters of this lens system are: (1) Working spectrum range: 8um~12um; (2) F number: ≤0.8; (3) Target surface: Φ≥20mm; (4) Distortion: ≤1%; The total focal length of the lens system is f, and the focal lengths of the lenses from the object plane to the image plane are f1, f2, f3, f4, f5, and f6, respectively. The relationship between each lens and the total focal length is as follows: 50 <f1 / f<100;5<f2 / f<10;-5<f3 / f<0;0<f4 / f<5;0<f5 / f<5;0<f6 / f<5。 2. The large overload large aperture infrared lens system according to claim 1, characterized in that: Parameter table of each lens: Aspherical lens related data: The aspheric expression is: Z represents the position along the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, k represents the cone coefficient, α4, α6, α8, α 10 ...represents the aspheric coefficient. In aspheric data, En represents "×10 -n ", for example, -1.56E-07 represents -1.56×10 -7 .

3. The large overload large aperture infrared lens system according to claim 1, characterized in that: The meniscus positive lens A and the meniscus positive lens B are installed at the front end of the main lens barrel and locked by a front pressure ring. A first spacer is provided between the meniscus positive lens A and the meniscus positive lens B for setting an air gap between the two; the meniscus negative lens C, the biconvex positive lens D, the meniscus positive lens E, and the meniscus positive lens F are installed at the rear end of the main lens barrel and locked by a rear pressure ring. The meniscus negative lens C, the biconvex positive lens D, the meniscus positive lens E, and the meniscus positive lens F are provided with corresponding second spacers, third spacers, fourth spacers, and fifth spacers between each other, and the air gap between each lens is controlled by controlling each spacer.

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