CN111413789A - Infrared optical lens and infrared optical equipment - Google Patents

Abstract

The invention discloses an infrared optical lens and an infrared optical device. The infrared optical lens includes a first lens, a second lens, a third lens and a fourth lens from the object side to the image side. The first lens, the second lens The object side and the image side of the lens, the third lens and the fourth lens are all aspherical surfaces, and the effective focal length f1 of the first lens and the total effective focal length f of the infrared optical lens satisfy 1.2<f1/f<1.5, and 3.69mm ≤f≤3.70mm, the wavelength range of the light source is 812nm～832nm. The infrared optical lens and infrared optical device of the present invention can improve the resolution of the lens, reduce optical distortion, and ensure the relative illuminance by optimizing parameters such as the thickness, focal length, effective diameter of the lens, etc., and can be widely used in optics in the infrared band. in the device.

Description

Infrared optical lens and infrared optical equipment

technical field

The invention belongs to the technical field of optical lenses, and in particular relates to an infrared optical lens and an infrared optical device.

Background technique

In recent years, with the rapid development of depth recognition technology, 3D depth cameras have become more and more widely used in AR enhancement technology. The structured light scheme is one of the mainstream directions of depth recognition technology. The principle of depth recognition is: the projection lens module projects a special image (coding pattern or dot matrix image) onto the object; uses an imaging receiving module to receive The image information reflected back by the object is described; the depth information of the object is obtained by processing the received image information through the back-end algorithm. The imaging receiving lens is one of the core components of the structured light depth recognition technology, and its optical performance will greatly affect the accuracy of depth recognition.

Optical distortion (Distortion) and resolution (Resolution) are two important indicators for evaluating optical performance, and the optical lens of the prior art still cannot effectively guarantee optical distortion and resolution in the infrared band.

Therefore, in view of the above technical problems, it is necessary to provide an infrared optical lens and an infrared optical device.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an infrared optical lens and an infrared optical device.

In order to achieve the above purpose, the technical solution provided by an embodiment of the present invention is as follows:

An infrared optical lens comprising a first lens, a second lens, a third lens and a fourth lens from the object side to the image side, the first lens, the second lens, the third lens and the fourth lens The object and image sides of the lens are both aspherical, where:

The first lens has a positive refractive power, and the optical axis of the object side surface is a convex surface;

The second lens has positive refractive power or negative refractive power, the optical axis of the object side is concave, and the optical axis of the image side is convex;

The third lens has a positive refractive power, the optical axis of the object side is concave, and the optical axis of the image side is convex;

The fourth lens has a negative refractive power, the object side surface is convex at the optical axis, the object side is off-axis at least one concave surface, the image side optical axis is concave, and the image side is off-axis at least one convex surface;

The effective focal length f1 of the first lens and the total effective focal length f of the infrared optical lens satisfy 1.2<f1/f<1.5, and 3.69mm≤f≤3.70mm, and the wavelength range of the light source is 812nm-832nm.

In one embodiment, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens and the total effective focal length f of the infrared optical lens satisfy 1.5<|f/f1|+|f /f2|+|f/f3|<2.1.

In one embodiment, the curvature radius R1 of the object side surface of the first lens and the total effective focal length f of the infrared optical lens satisfy 0.1<R1/f<0.6.

In one embodiment, the sum ΣCT of the center thicknesses of the first lens, the second lens, the third lens and the fourth lens on the optical axis is at the same level as the image plane from the object side of the first lens to the imaging plane of the infrared optical lens. The separation distance TTL on the optical axis satisfies 0.45<∑CT/TTL<0.51.

In one embodiment, the on-axis distance SAG11 from the intersection of the object side of the first lens and the optical axis to the effective semi-aperture vertex of the object side of the first lens and the center thickness CT1 of the first lens on the optical axis satisfy 0.35<SAG11/CT1<0.45.

In one embodiment, the maximum effective half-aperture DT42 of the image side of the fourth lens and the half of the diagonal length of the effective pixel area of the photosensitive element on the imaging surface of the infrared optical lens ImgH satisfy 0.68<DT42/ImgH<0.72 .

In one embodiment, the total effective focal length f of the infrared optical lens and the entrance pupil diameter EPD of the infrared optical lens satisfy 1.8<f/EPD<1.9.

In one embodiment, the distance TTL from the center of the object side surface of the first lens to the imaging surface of the infrared optical lens on the optical axis is longer than the diagonal of the effective pixel area on the imaging surface of the infrared optical lens Half of ImgH satisfy 1.7<TTL/ImgH<1.85.

In one embodiment, in the infrared optical lens:

The effective aperture of the object side of the first lens is 0.97mm～0.98mm, and the effective aperture of the image side is 0.99mm～1.05mm;

The effective aperture of the object side of the second lens is 0.95mm～1.04mm, and the effective aperture of the image side is 1.11mm～1.16mm;

The effective aperture of the object side of the third lens is 1.14mm～1.19mm, and the effective aperture of the image side is 1.45mm～1.57mm;

The effective aperture of the object side of the fourth lens is 2.05mm-2.14mm, and the effective aperture of the image side is 2.52mm-2.61mm.

In one embodiment, the infrared optical lens further includes:

filter, located on the image side of the fourth lens;

a lens barrel for encapsulating the first lens, the second lens, the third lens and the fourth lens;

A plurality of spacer rings are encapsulated between the first lens and the second lens, and/or the second lens and the third lens, and/or the third lens and the fourth lens.

The technical solution provided by an embodiment of the present invention is as follows:

An infrared optical device is provided with at least one of the above-mentioned infrared optical lenses.

Compared with the prior art, the present invention has the following advantages:

The infrared optical lens and infrared optical device of the present invention can improve the resolution of the lens, reduce optical distortion, and ensure relative illuminance by optimizing parameters such as the thickness, focal length, effective diameter of the lens, etc. in the device.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

1 is a schematic structural diagram of a mid-infrared optical lens of the present invention;

Fig. 2 is the light transmission schematic diagram of the mid-infrared optical lens of the present invention;

Fig. 3 is the resolution curve diagram of the optical lens in Embodiment 1 of the present invention;

4 is a distortion curve diagram of an optical lens in Embodiment 1 of the present invention;

FIG. 5 is a relative illuminance curve diagram of the optical lens in the first embodiment of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the various embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and the structural, method, or functional transformations made by those of ordinary skill in the art based on these embodiments are all included in the protection scope of the present invention.

1 and 2, the present invention discloses an infrared optical lens, which includes a first lens 10, a second lens 20, a third lens 30 and a fourth lens 40 from the object side to the image side, The object side and the image side of the first lens 10, the second lens 20, the third lens 30 and the fourth lens 40 are all aspherical surfaces, wherein:

The first lens 10 has a positive refractive power, and the optical axis of the object side surface is a convex surface;

The second lens 20 has positive refractive power or negative refractive power, and the optical axis of the object side is concave, and the optical axis of the image side is convex;

The third lens 30 has a positive refractive power, the optical axis of the object side is concave, and the optical axis of the image side is convex;

The fourth lens 40 has a negative optical power, the object side surface is convex at the optical axis, the object side surface is at least one concave surface off-axis, the image side surface is concave at the optical axis, and the image side surface is off-axis at least one convex surface.

Further, the infrared optical lens also includes:

The filter 50 is located on the image side of the fourth lens 40;

The lens barrel 60 is used to package the first lens 10, the second lens 20, the third lens 30 and the fourth lens 40;

A plurality of spacer rings 70 are encapsulated between the first lens and the second lens, the second lens and the third lens, and the third lens and the fourth lens.

In the present invention, the effective focal length f1 of the first lens 10 and the total effective focal length f of the infrared optical lens satisfy 1.2<f1/f<1.5, and 3.69mm≤f≤3.70mm, and the wavelength range of the light source is 812nm～832nm. Reasonable configuration of the effective focal length of the first lens can effectively correct the spherical aberration of the lens and ensure high image quality.

Preferably, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens and the total effective focal length f of the infrared optical lens satisfy 1.5<|f/f1|+|f/f2|+ |f/f3|<2.1.

Preferably, the curvature radius R1 of the object side of the first lens and the total effective focal length f of the infrared optical lens satisfy 0.1<R1/f<0.6, which can better correct the aberration in the off-axis field of view of the system and ensure the central field of view. high resolution; at the same time, it is beneficial to obtain a larger lens aperture.

Preferably, the sum of the center thicknesses of the first lens, the second lens, the third lens and the fourth lens on the optical axis ΣCT and the separation distance on the optical axis from the object side of the first lens to the imaging surface of the infrared optical lens TTL satisfies 0.45<∑CT/TTL<0.51, which can better correct the aberration in the off-axis field of view of the imaging system, and at the same time is beneficial to make each lens have better machinability.

Preferably, the on-axis distance SAG11 from the intersection of the object side of the first lens and the optical axis to the effective semi-aperture vertex of the object side of the first lens and the central thickness CT1 of the first lens on the optical axis satisfy 0.35<SAG11/CT1<0.45.

Preferably, the maximum effective half-aperture DT42 on the image side of the fourth lens and ImgH, which is half the diagonal length of the effective pixel area of the photosensitive element on the imaging surface of the infrared optical lens, satisfy 0.68<DT42/ImgH<0.72, which is beneficial to meet the requirements of miniaturization requirements, and at the same time guarantee a high relative brightness.

Preferably, the total effective focal length f of the infrared optical lens and the entrance pupil diameter EPD of the infrared optical lens satisfy 1.8<f/EPD<1.9.

Preferably, the distance TTL from the center of the object side surface of the first lens to the imaging surface of the infrared optical lens on the optical axis and half of the diagonal length of the effective pixel area on the imaging surface of the infrared optical lens ImgH satisfy 1.7<TTL/ImgH< 1.85.

In the present invention, the effective aperture of the object side of the first lens is 0.97mm～0.98mm, the effective aperture of the image side is 0.99mm～1.05mm; the effective aperture of the object side of the second lens is 0.95mm～1.04mm, and the effective aperture of the image side is 0.95mm～1.04mm. The aperture is 1.11mm～1.16mm; the effective aperture of the object side of the third lens is 1.14mm～1.19mm, the effective aperture of the image side is 1.45mm～1.57mm; the effective aperture of the fourth lens object side is 2.05mm～2.14mm, The effective diameter of the image side is 2.52mm to 2.61mm.

Preferably, the effective aperture of the object side of the first lens is 0.978mm～0.980mm, and the effective aperture of the image side is 1.001mm～1.032mm; the effective aperture of the object side of the second lens is 0.999mm～1.030mm, and the effective aperture of the image side is 0.999mm～1.030mm. The effective aperture of the object side of the third lens is 1.140mm to 1.181mm, and the effective aperture of the image side is 1.465mm to 1.568mm; the effective aperture of the object side of the fourth lens is 2.067mm to 2.137mm. The effective diameter of the side is 2.520mm to 2.601mm.

The invention improves the resolution and reduces the distortion by controlling the ratio of the central thickness to the total thickness of each lens and rationally distributing the focal length ratio of each lens.

The present invention will be further described below in conjunction with specific embodiments.

Example 1:

In this embodiment, the total effective focal length of the infrared optical lens is f=3.697mm, which includes the first lens 10, the second lens 20, the third lens 30 and the fourth lens 40, all of which are resin lenses, the center is the lens, and the edges are subjected to corrosion extinction treatment , its material, refractive index and effective focal length are as follows:

The material of the first lens 10 is E48R, the refractive index is 1.531, the effective focal length f1=5.190mm, the effective aperture of the object side is 0.979mm, and the effective aperture of the image side is 1.008mm;

The material of the second lens 20 is EP5000, the refractive index is 1.635, the effective focal length f2=23.898mm, the effective aperture of the object side is 1.000mm, and the effective aperture of the image side is 1.124mm;

The material of the third lens 30 is E48R, the refractive index is 1.531, the effective focal length f3=3.112mm, the effective aperture of the object side is 1.145mm, and the effective aperture of the image side is 1.567mm;

The material of the fourth lens 40 is E48R, the refractive index is 1.531, the effective focal length f4=-4.231mm, the effective aperture of the object side is 2.078mm, and the effective aperture of the image side is 2.541mm.

The ratio of the effective focal length f1 of the first lens 10 to the total effective focal length f of the infrared optical lens is f1/f=1.404;

The effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens and the total effective focal length f of the infrared optical lens satisfy |f/f1|+|f/f2|+|f/f3| = 2.055.

The curvature radius of the object side surface of the first lens is R1=0.713mm, and its ratio to the total effective focal length f of the infrared optical lens is R1/f=0.193.

The sum of the central thicknesses of the first lens, the second lens, the third lens and the fourth lens on the optical axis ∑CT=2.754mm, the distance from the object side of the first lens to the imaging surface of the infrared optical lens on the optical axis TTL=5.495mm, ∑CT/TTL=0.501.

The on-axis distance SAG11=0.273mm from the intersection of the object side and the optical axis of the first lens to the vertex of the effective semi-aperture on the object side of the first lens, the central thickness of the first lens on the optical axis CT1=0.713mm, SAG11/CT1=0.383 .

The maximum effective half-aperture of the image side of the fourth lens is DT42=2.078mm, the half of the diagonal length of the effective pixel area of the photosensitive element on the imaging surface of the infrared optical lens is ImgH=3.000mm, and DT42/ImgH=0.693.

The total effective focal length of the infrared optical lens is f=3.697mm, the entrance pupil diameter of the infrared optical lens is EPD=1.957mm, and f/EPD=1.890.

The distance from the center of the object side of the first lens to the imaging surface of the infrared optical lens on the optical axis TTL=5.495mm, the ratio between it and the half ImgH of the diagonal length of the effective pixel area on the imaging surface of the infrared optical lens TTL/ImgH =1.832.

The surface of each lens is aspheric and satisfies the aspheric formula:

Among them, Z is the aspherical curve, C=1/r (r is the paraxial spherical radius), Y is the radius of curvature, K is the conic constant (quadratic surface constant), a, b, c, d, e...respectively Higher order coefficients (4th, 6th, 8th, 10th, 12th...).

The object side and the image side of the first lens 10 are respectively S1 and S2, the object side and the image side of the second lens 20 are S3 and S4 respectively, the object side and the image side of the third lens 30 are S5 and S6 respectively, the fourth The object side and the image side of the lens 40 are S7 and S8, respectively, and S1-SAG to S8-SAG are the sagittal heights (0.2 mm, 0.4 mm, 0.6 mm, and 0.8 mm) of each surface, respectively. Its surface parameters are detailed in Table 1 and Table 2.

Table 1: Lens Surface Parameters Table 1

Table 2: Lens Surface Parameters Table 2

S1-SAG S2-SAG S3-SAG S4-SAG 0.2 0.01053133471831 0.00358468367088 -0.0029627972579 -0.0041806080557 0.4 0.0425848711431 0.01401446798168 -0.0142510824849 -0.0306896222098 0.6 0.09762709732581 0.02974991466551 -0.0430703504256 -0.107575797538 0.8 0.17821387441138 0.04399101030559 -0.1127596259901 -0.2651009697167 S5-SAG S6-SAG S7-SAG S8-SAG 0.2 -0.0121891159602 -0.0194555166513 0.02641705079163 0.08433036546007 0.4 -0.0770284860696 -0.168859781545 0.14796709693557 0.36194696248054 0.6 -0.2165234475881 -0.4596294670822 0.17868469806762 0.49149316737987 0.8 -0.4897369094091 -0.9396372914827 -0.0255041738777 0.13647018150703

Referring to FIG. 3, there is shown a graph of the imaging height (Real Image Height)-resolution (MTF) in this embodiment, from top to bottom, the meridional direction (S) and the arc loss direction (T) are respectively when the spatial frequency is 0%. ), the meridional direction (S) and the missing arc direction (T) when the spatial frequency is 33%, the meridional direction (S) and the missing arc direction (T) when the spatial frequency is 66%, and the meridional direction (S) when the spatial frequency is 132% ) and the resolution curve of the loss of direction (T), it can be seen that the infrared optical lens in this embodiment has a good resolution at high frequencies, and the central area to the peripheral area is relatively smooth.

Referring to FIG. 4 as a distortion curve diagram in this embodiment, it can be seen that the distortion of the infrared optical lens in this embodiment is relatively small, less than 1.7%. Referring to FIG. 5, which is a graph showing the relative field height (Relative Field Height)-relative Illumination (Relative Illumination) in this embodiment, it can be seen that the relative illuminance of the infrared optical lens in this embodiment is greater than 32%.

Embodiment 2:

In this embodiment, the total effective focal length of the infrared optical lens is f=3.693mm, and the first lens, the second lens, the third lens and the fourth lens are all resin lenses, the center is the lens, and the edge is subjected to corrosion extinction treatment. The refractive index and effective focal length are as follows:

The material of the first lens is E48R, the refractive index is 1.531, the effective focal length f1=4.565mm, the effective aperture of the object side is 0.979mm, and the effective aperture of the image side is 1.027mm;

The material of the second lens is EP5000, the refractive index is 1.635, the effective focal length f2=-115.52mm, the effective aperture of the object side is 1.026mm, and the effective aperture of the image side is 1.144mm;

The material of the third lens is E48R, the refractive index is 1.531, the effective focal length is f3=4.133mm, the effective aperture of the object side is 1.169mm, and the effective aperture of the image side is 1.472mm;

The material of the fourth lens is E48R, the refractive index is 1.531, the effective focal length f4=-5.416mm, the effective aperture of the object side is 2.101mm, and the effective aperture of the image side is 2.554mm.

The ratio of the effective focal length f1 of the first lens to the total effective focal length f of the infrared optical lens is f1/f=1.236;

The effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens and the total effective focal length f of the infrared optical lens satisfy |f/f1|+|f/f2|+|f/f3| =1.670.

The curvature radius of the object side surface of the first lens is R1=1.751mm, and its ratio to the total effective focal length f of the infrared optical lens is R1/f=0.474.

The sum of the central thicknesses of the first lens, the second lens, the third lens and the fourth lens on the optical axis ∑CT=2.537mm, the distance from the object side of the first lens to the imaging surface of the infrared optical lens on the optical axis TTL=5.099mm, ∑CT/TTL=0.498.

The on-axis distance from the intersection of the object side and the optical axis of the first lens to the vertex of the effective semi-aperture on the object side of the first lens is SAG11=0.299mm, the center thickness of the first lens on the optical axis CT1=0.738mm, SAG11/CT1=0.405 .

The maximum effective half aperture of the image side of the fourth lens is DT42=2.101mm, the half of the diagonal length of the effective pixel area of the photosensitive element on the imaging surface of the infrared optical lens is ImgH=3.000mm, and DT42/ImgH=0.700.

The total effective focal length of the infrared optical lens is f=3.693mm, the entrance pupil diameter of the infrared optical lens is EPD=1.957mm, and f/EPD=1.887.

The distance from the center of the object side of the first lens to the imaging surface of the infrared optical lens on the optical axis TTL=5.099mm, the ratio between it and the half ImgH of the diagonal length of the effective pixel area on the imaging surface of the infrared optical lens TTL/ImgH =1.700.

Embodiment three:

In this embodiment, the total effective focal length of the infrared optical lens is f=3.693mm, and the first lens, the second lens, the third lens and the fourth lens are all resin lenses, the center is the lens, and the edge is subjected to corrosion extinction treatment. The refractive index and effective focal length are as follows:

The material of the first lens is E48R, the refractive index is 1.531, the effective focal length f1=4.589mm, the effective aperture of the object side is 0.979mm, and the effective aperture of the image side is 1.026mm;

The material of the second lens is EP5000, the refractive index is 1.635, the effective focal length f2=69.587mm, the effective aperture of the object side is 1.024mm, and the effective aperture of the image side is 1.133mm;

The third lens material is E48R, the refractive index is 1.531, the effective focal length is f3=5.097mm, the effective aperture of the object side is 1.151mm, and the effective aperture of the image side is 1.519mm;

The fourth lens material is E48R, the refractive index is 1.531, the effective focal length f4=-7.044mm, the effective aperture of the object side is 2.136mm, and the effective aperture of the image side is 2.600mm.

The ratio of the effective focal length f1 of the first lens to the total effective focal length f of the infrared optical lens is f1/f=1.243;

The effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens and the total effective focal length f of the infrared optical lens satisfy |f/f1|+|f/f2|+|f/f3| =1.582.

The curvature radius of the object side surface of the first lens is R1=1.764mm, and its ratio to the total effective focal length f of the infrared optical lens is R1/f=0.478.

The sum of the central thicknesses of the first lens, the second lens, the third lens and the fourth lens on the optical axis ∑CT=2.593mm, the distance from the object side of the first lens to the imaging surface of the infrared optical lens on the optical axis TTL=5.183mm, ∑CT/TTL=0.500.

The on-axis distance SAG11=0.296mm from the intersection of the object side and the optical axis of the first lens to the vertex of the effective semi-aperture on the object side of the first lens, the central thickness of the first lens on the optical axis CT1=0.697mm, SAG11/CT1=0.425 .

The maximum effective half aperture of the image side of the fourth lens is DT42=2.136mm, the half of the diagonal length of the effective pixel area of the photosensitive element on the imaging surface of the infrared optical lens is ImgH=3.000mm, and DT42/ImgH=0.712.

The total effective focal length of the infrared optical lens is f=3.693mm, the entrance pupil diameter of the infrared optical lens is EPD=1.957mm, and f/EPD=1.887.

The distance from the center of the object side of the first lens to the imaging surface of the infrared optical lens on the optical axis TTL=5.183mm, and the ratio between it and the half ImgH of the diagonal length of the effective pixel area on the imaging surface of the infrared optical lens TTL/ImgH =1.728.

As can be seen from the above technical solutions, the present invention has the following beneficial effects:

The infrared optical lens and infrared optical device of the present invention can improve the resolution of the lens, reduce optical distortion, and ensure relative illuminance by optimizing parameters such as the thickness, focal length, effective diameter of the lens, etc. in the device.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes within the meaning and scope of the equivalents of , are included in the present invention. Any reference signs in the claims shall not be construed as limiting the involved claim.

In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (11)

1. An infrared optical lens, characterized in that, the infrared optical lens comprises a first lens, a second lens, a third lens and a fourth lens from the object side to the image side, the first lens, the second lens, The object side and the image side of the third lens and the fourth lens are both aspherical, wherein: The first lens has a positive refractive power, and the optical axis of the object side surface is a convex surface; The second lens has positive refractive power or negative refractive power, the optical axis of the object side is concave, and the optical axis of the image side is convex; The third lens has a positive refractive power, the optical axis of the object side is concave, and the optical axis of the image side is convex; The fourth lens has a negative refractive power, the object side surface is convex at the optical axis, the object side is off-axis at least one concave surface, the image side optical axis is concave, and the image side is off-axis at least one convex surface; The effective focal length f1 of the first lens and the total effective focal length f of the infrared optical lens satisfy 1.2<f1/f<1.5, and 3.69mm≤f≤3.70mm, and the wavelength range of the light source is 812nm-832nm. 2. The infrared optical lens according to claim 1, wherein the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens and the total effective focal length of the infrared optical lens f satisfies 1.5<|f/f1|+|f/f2|+|f/f3|<2.1. 3 . The infrared optical lens according to claim 1 , wherein the curvature radius R1 of the object side surface of the first lens and the total effective focal length f of the infrared optical lens satisfy 0.1<R1/f<0.6. 4 . 4 . The infrared optical lens according to claim 1 , wherein the sum ΣCT of the center thicknesses of the first lens, the second lens, the third lens and the fourth lens on the optical axis is the same as that of the first lens. 5 . The separation distance TTL from the object side of the lens to the imaging surface of the infrared optical lens on the optical axis satisfies 0.45<∑CT/TTL<0.51. 5. The infrared optical lens according to claim 1, wherein the on-axis distance SAG11 from the intersection of the object side of the first lens and the optical axis to the effective half-aperture vertex of the object side of the first lens is the same as the distance SAG11. The center thickness CT1 of the first lens on the optical axis satisfies 0.35<SAG11/CT1<0.45. 6 . The infrared optical lens according to claim 1 , wherein the maximum effective half-aperture DT42 on the image side of the fourth lens is diagonal to the effective pixel area of the photosensitive element on the imaging surface of the infrared optical lens. 7 . The long half of ImgH satisfies 0.68<DT42/ImgH<0.72. 7 . The infrared optical lens according to claim 1 , wherein the total effective focal length f of the infrared optical lens and the entrance pupil diameter EPD of the infrared optical lens satisfy 1.8<f/EPD<1.9. 8 . 8 . The infrared optical lens according to claim 1 , wherein the distance TTL from the center of the object side surface of the first lens to the imaging surface of the infrared optical lens on the optical axis is the same as that of the infrared optical lens. 9 . Half of the diagonal length of the effective pixel area on the imaging surface of the lens, ImgH, satisfies 1.7<TTL/ImgH<1.85. 9. The infrared optical lens according to claim 1, wherein, in the infrared optical lens: The effective aperture of the object side of the first lens is 0.97mm～0.98mm, and the effective aperture of the image side is 0.99mm～1.05mm; The effective aperture of the object side of the second lens is 0.95mm～1.04mm, and the effective aperture of the image side is 1.11mm～1.16mm; The effective aperture of the object side of the third lens is 1.14mm～1.19mm, and the effective aperture of the image side is 1.45mm～1.57mm; The effective aperture of the object side of the fourth lens is 2.05mm-2.14mm, and the effective aperture of the image side is 2.52mm-2.61mm. 10. The infrared optical lens according to claim 1, wherein the infrared optical lens further comprises: filter, located on the image side of the fourth lens; a lens barrel for encapsulating the first lens, the second lens, the third lens and the fourth lens; A plurality of spacer rings are encapsulated between the first lens and the second lens, and/or the second lens and the third lens, and/or the third lens and the fourth lens. 11 . An infrared optical device, characterized in that, at least one infrared optical lens according to any one of claims 1 to 10 is provided in the infrared optical device.

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