Large overload large aperture infrared lens system

Abstract

The present application relates to a kind of big overload big aperture infrared lens system, it is characterized in that: the lens is made of six pieces of lens, from object plane to image plane is sequentially provided with: convex surface towards object's meniscus positive lens A, material is germanium single crystal;Convex surface towards object's meniscus positive lens B, material is zinc sulfide;Convex surface towards object's meniscus negative lens C, material is germanium single crystal;Biconvex positive lens D, material is chalcogenide glass;Convex surface towards object's meniscus positive lens E, material is chalcogenide glass;Convex surface towards object's meniscus positive lens F, material is chalcogenide glass;The lens operating wave band is between 8um~14um, with big light aperture, can receive more target signal energy, system target surface big field of view is big, can search larger range target.

Description

TECHNICAL FIELD

[0001] The present application relates to an infrared lens, in particular to a large overload large aperture infrared lens system. BACKGROUND

[0002] The optical system receives more energy when the aperture is larger under the same focal length, and the detection ability of the weak and small target is stronger, that is, the system detection sensitivity is higher; however, the F number of the current non-cooled long-wave infrared lens is usually 1.0, and the non-cooled long-wave infrared lens with F number ≤0.8 is extremely rare.

[0003] In addition, the long-wave transmission type lens has a strong use environment vibration, and the strength of the lens and the structure of the lens is required to be higher, and once the strength does not meet the use requirement, the product is easily damaged or the imaging quality is reduced. SUMMARY

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

[0005] The technical scheme of the present application is a large overload large aperture infrared lens system, characterized in that the lens is composed of six lenses, and from the object plane to the image plane, there are in sequence: a convex surface toward the object plane of a meniscus positive lens A, which is made of germanium single crystal; a convex surface toward the object plane of a meniscus positive lens B, which is made of zinc sulfide; a convex surface toward the object plane of a meniscus negative lens C, which is made of germanium single crystal; a double-convex positive lens D, which is made of sulfur glass; a convex surface toward the object plane of a meniscus positive lens E, which is made of sulfur glass; and a convex surface toward the object plane of a meniscus positive lens F, which is made of sulfur glass.

[0006] The specific performance parameters of the lens system are as follows: (1) working spectral 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 in sequence, and 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; and 0<f6 / f<5.

[0009] Further, the lens parameter table is as follows:

[0010]

[0011] ; lens aspherical surface related data:

[0012]

[0013]

[0014] Aspherical surface expression is:

[0015]

[0016] Z represents the position of the optical axis direction, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, k represents the conic coefficient, alpha4, alpha6, alpha8, alpha 10 ... represents the aspherical coefficient. In the aspherical surface data, E-n represents "x10 -n ", for example -1.56E-07 represents -1.56x10 -7 .

[0017] Further, 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 the front compression ring, and the first spacer ring is arranged between the meniscus positive lens A and the meniscus positive lens B to set the air gap therebetween; 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 the rear compression ring, and the corresponding second spacer ring, third spacer ring, fourth spacer ring and fifth spacer ring are arranged between the meniscus negative lens C, the biconvex positive lens D, the meniscus positive lens E and the meniscus positive lens F, so as to control the air gap between the lenses by controlling the spacer rings.

[0018] The present application is composed of six lenses, adopts a four-infrared-material-combined folding / diffraction hybrid optical system, and combines the use of aspherical surface correction system aberration; and the working waveband of the lens is between 8um and 14um, has a large light aperture, can realize high energy concentration, high response sensitivity, strong weak and small target detection capability, and the advantages of receiving more target signal energy. BRIEF DESCRIPTION OF DRAWINGS

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

[0020] Figure 2 is the lens assembly structure schematic diagram of the present application;

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

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

[0023] Figure 5MTF value of the lens system of the present application (+60℃) is shown in the following table:

[0024] Figure 6 Distortion diagram of the lens system of the present application is shown in the following table:

[0025] Figure 7 Relative illumination curve diagram of the lens system of the present application is shown in the following table. DETAILED DESCRIPTION

[0026] Technical solution of the present application: a large overload large aperture infrared lens system, the lens is composed of six lenses, from the object plane to the image plane, there are: convex surface towards the object side of the meniscus positive lens A, the material is germanium single crystal; convex surface towards the object side of the meniscus positive lens B, the material is zinc sulfide; convex surface towards the object side of the meniscus negative lens C, the material is germanium single crystal; biconvex positive lens D, the material is chalcogenide glass; convex surface towards the object side of the meniscus positive lens E, the material is chalcogenide glass; convex surface towards the object side of the meniscus positive lens F, the material is chalcogenide glass;

[0027] The specific performance parameters of this lens system are as follows: (1) working spectral 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 length of each lens from the object plane to the image plane is f1, f2, f3, f4, f5 and f6, respectively, and each lens has the following relationship with the total focal length: 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, the lens has the following advantages:

[0031] a) The present application has a large light aperture, which can collect more target signal energy, has strong detection ability for small target, and has higher detection sensitivity;

[0032] b) The present application adopts fold / diffraction hybrid structure, which can achieve achromatism and thermal difference effect with less material, reduce the size of the system, and realize normal imaging in high and low temperature environment;

[0033] c) The lens has good anti-vibration and impact ability, which solves the problem that the traditional small fixed focus lens cannot achieve the expected environmental adaptability effect due to small size and compact structure;

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

[0035] The above lens parameter table:

[0036]

[0037] Aspherical lens data:

[0038] [alpha]4 [alpha]6 [alpha]8 10 ]]> ​ Diffractive surface S2 -2.49E-07 3.13E-10 7.87E-13 -1.27E-15 Aspheric surface S4 7.08E-06 -1.77E-10 -6.07E-12 2.90E-14 Diffractive surface S6 -3.89E-06 3.34E-09 -1.08E-11 7.90E-15 Aspheric surface S7 5.66E-06 -1.69E-08 1.93E-11 -2.75E-14 Aspheric surface S8 -2.56E-06 -1.12E-08 1.46E-11 -1.29E-14 Diffractive surface S9 -4.80E-06 -2.33E-09 -8.37E-13 -1.51E-14 Aspheric surface S11 -1.45E-05 -1.67E-09 -1.71E-10 7.37E-13

[0039] The expression for an aspherical surface is:

[0040]

[0041] Z represents the position along the optical axis, r represents the height perpendicular to the optical axis, c represents the radius of curvature, and k represents the conic coefficient, α4, α6, α8, α... 10 ... represents the aspherical coefficient. In aspherical data, En represents "×10 -n For example, -1.56E-07 represents -1.56 × 10⁻⁶. -7 .

[0042] Depend on Figures 3-5 It can be seen that the lens's MTF curve is close to the diffraction limit, and its value is greater than 0.35 at 42 lp / mm across the entire field of view, indicating 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 relative illumination at the edges of the system is greater than 80%, and the illumination on the system image plane is relatively uniform.

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

[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 the 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. The air gap between each lens is controlled by controlling each spacer.

[0045] This invention consists of six lenses, employs a hybrid optical system combining four infrared materials, and incorporates an aspherical aberration correction system. The lens operates in the 8µm to 14µm wavelength range, features a large aperture, and offers advantages such as high energy concentration, high response sensitivity, strong detection capability for small targets, and the ability to receive more target signal energy.

Claims

1. A large overload, large aperture, infrared lens system characterized by: The lens is composed of six lenses, which are provided with, from an object plane to an image plane, a convex-to-object positive meniscus lens A made of germanium single crystal, a convex-to-object positive meniscus lens B made of zinc sulfide, a convex-to-object negative meniscus lens C made of germanium single crystal, a biconvex positive lens D made of chalcogenide glass, a convex-to-object positive meniscus lens E made of chalcogenide glass, and a convex-to-object positive meniscus lens F made of chalcogenide glass; The specific performance parameters of the lens system are: (1) working spectral range: 8-12 um; (2) F number: ≤0.8; (3) target surface: Φ≥20 mm; (4) distortion: ≤1%; The total focal length of the lens system is f, the focal lengths of the lenses from the object plane to the image plane are f1, f2, f3, f4, f5 and f6 in sequence, and the lenses and the total focal length have the following relationships: 50<f1 / f<100; 5<f2 / f<10; -5<f3 / f<0; 0<f4 / f<5; 0<f5 / f<5; 0<f6 / f<5; the lens parameters are shown in the table: Lens aspherical surface related data: The aspherical surface expression is: Z represents the position along the optical axis, r represents the height perpendicular to the optical axis, c represents the radius of curvature, and k represents the conic coefficient, α4, α6, α8, α... 10 ... represents the aspherical coefficient.

2. The large overload, large aperture, infrared lens system of claim 1, wherein: The convex-to-object positive meniscus lens A and the convex-to-object positive meniscus lens B are installed at the front end of the main lens barrel and locked by a front compression ring, a first spacer ring is arranged between the convex-to-object positive meniscus lens A and the convex-to-object positive meniscus lens B for setting the air gap therebetween; the convex-to-object negative meniscus lens C, the biconvex positive lens D, the convex-to-object positive meniscus lens E and the convex-to-object positive meniscus lens F are installed at the rear end of the main lens barrel and locked by a rear compression ring, and corresponding second, third, fourth and fifth spacer rings are arranged between the convex-to-object negative meniscus lens C, the biconvex positive lens D, the convex-to-object positive meniscus lens E and the convex-to-object positive meniscus lens F for controlling the air gaps between the lenses.

Images