WO2022000381A1 - Infrared imaging lens - Google Patents

Abstract

The present application provides an infrared imaging lens, comprising a first lens, a second lens, a third lens, and a fourth lens which are sequentially disposed from an object side to an image side. The first lens, the second lens, and the third lens have positive focal power, and the fourth lens has negative focal power. The first lens has a convex surface on the paraxial object side and a concave surface on the paraxial image side; the second lens has a convex surface or plane on the paraxial object side; the third lens has a concave surface on the paraxial object side and a convex surface on the paraxial image side; and the fourth lens has a convex surface on the paraxial object side and a concave surface on the paraxial image side. At least one of the two surfaces of each lens is an aspheric surface. The focal length f of the lens, the maximum image height Y' on an imaging surface and the distance TTL from the object side surface of the first lens to the imaging surface satisfy a preset condition, so that the FOV of the lens is greater than a first threshold and less than a second threshold, and F number is less than a third threshold.

Description

Infrared imaging lens technical field

The embodiments of the present application relate to the field of optical imaging, and more particularly, to an infrared imaging lens.

Background technique

With the rise of face recognition, somatosensory games and pattern recognition, 3D depth detection has become a hot spot. The 940nm light source is usually used as the signal light source in the 3D depth test. One is to avoid the interference of the visible light band in the sunlight to the signal, and the other is that the water molecules in the air have less absorption of the 940nm light. As a signal collection device in depth detection, infrared imaging lens is crucial to the accuracy and field of view in depth detection. Therefore, how to improve the performance of the infrared imaging lens has become an urgent problem to be solved.

SUMMARY OF THE INVENTION

The embodiment of the present application provides an infrared imaging lens, which has a larger field of view and a smaller F-number.

In a first aspect, an infrared imaging lens is provided, comprising a first lens, a second lens, a third lens and a fourth lens arranged in sequence from the object side to the image side, wherein:

The first lens is a lens with positive refractive power, the first lens is convex on the paraxial object side, and is concave on the paraxial image side, and at least two surfaces of the first lens have a convex surface. One face is aspheric;

The second lens is a lens with positive refractive power, and the object-side surface of the second lens is a convex surface or a plane surface, and at least one of the two surfaces of the second lens is an aspheric surface;

The third lens is a lens with positive refractive power, and the third lens has a concave surface on the paraxial object side and a convex surface on the paraxial image side. At least two surfaces of the third lens have a concave surface. One face is aspheric;

The fourth lens is a lens with negative refractive power, and the fourth lens has a convex surface on the paraxial object side and a concave surface on the paraxial image side. Among the two surfaces of the fourth lens, at least One face is aspheric;

Wherein, the parameters of the lens satisfy predetermined conditions, so that the FOV of the lens is greater than a first threshold and less than a second threshold, and the F-number of the lens is less than a third threshold, wherein the lens's FOV The parameters include at least two of the following: the focal length f of the lens, the maximum image height Y' on the imaging plane of the lens, and the distance between the object side of the first lens and the imaging plane of the lens. Distance TTL.

In a possible implementation manner, the predetermined conditions include:

0<|Y’/(f*TTL)|<0.5; and/or,

0.48<Y’/TTL<0.51.

In a possible implementation manner, the first threshold is 65 degrees, and the second threshold is 80 degrees.

In a possible implementation manner, the third threshold is 1.25.

In a possible implementation manner, the TV distortion of the lens is less than a fourth threshold.

In a possible implementation, the fourth threshold is 5%.

In a possible implementation manner, the central thickness CT1 of the first lens and the central thickness CT2 of the second lens satisfy: 0.8<CT1/CT2<2.

In a possible implementation manner, the central thickness CT2 of the second lens and the central thickness CT3 of the third lens satisfy: 0.5<CT2/CT3<2.

In a possible implementation manner, the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 0.5<CT3/CT4<2.

In a possible implementation manner, the refractive index n ₁ >1.6 of the material of the first lens, and the dispersion coefficient v ₁ >20.0 of the material of the first lens.

In a possible implementation manner, the refractive index of the material of the second lens is n ₂ >1.6, and the dispersion coefficient of the material of the second lens is v ₂ >20.0.

In a possible implementation manner, the refractive index of the material of the third lens n ₃ >1.6, and the dispersion coefficient of the material of the third lens v ₃ >20.0.

In a possible implementation manner, the refractive index of the material of the fourth lens n ₄ >1.5, and the dispersion coefficient of the material of the fourth lens v ₄ >20.0.

In a possible implementation manner, the focal length f _{1 of} the first lens and the focal length f of the lens satisfy: 1<f ₁ /f<20.

_{In a possible implementation manner, the relationship between the focal length f 2 of} the second lens and the focal length f of the lens satisfies: 0<f ₂ /f<5.

_{In a possible implementation manner, the relationship between the focal length f 3 of} the third lens and the focal length f of the lens satisfies: 0<f ₃ /f<2.

_{In a possible implementation manner, the relationship between the focal length f 4 of} the fourth lens and the focal length f of the lens satisfies: -5<f ₄ /f<0.

In a possible implementation manner, the relationship between the focal length f ₁ of the first lens and the radius of curvature R1 of the object-side surface of the first lens satisfies: 0<f ₁ /R1<30.

In a possible implementation manner, the relationship between the focal length f ₁ of the first lens and the radius of curvature R2 of the image-side surface of the first lens satisfies: 0<f ₁ /R2<35.

In a possible implementation manner, the relationship between the focal length f ₂ of the second lens and the radius of curvature R3 of the object-side surface of the second lens satisfies: 0<f ₂ /R3<2.

In a possible implementation manner, the relationship between the focal length f ₂ of the second lens and the radius of curvature R4 of the image-side surface of the second lens satisfies: -1<f ₂ /R4<1.

In a possible implementation manner, the relationship between the focal length f ₃ of the third lens and the radius of curvature R5 of the object side surface of the third lens satisfies: -5<f ₃ /R5<-2.

In a possible implementation manner, the relationship between the focal length f ₃ of the third lens and the radius of curvature R6 of the image-side surface of the third lens satisfies: -6<f ₃ /R6<-2.

In a possible implementation manner, the relationship between the focal length f ₄ of the fourth lens and the radius of curvature R7 of the object-side surface of the fourth lens satisfies: -6<f ₄ /R7<0.

In a possible implementation manner, the relationship between the focal length f ₄ of the fourth lens and the radius of curvature R8 of the image-side surface of the fourth lens satisfies: -10<f ₄ /R8<-2.

In a possible implementation manner, the curvature radius R1 of the object side surface of the first lens and the curvature radius R2 of the image side surface of the first lens satisfy: 0<R1/R2<2.

In a possible implementation manner, the curvature radius R3 of the object side surface of the second lens and the curvature radius R4 of the image side surface of the second lens satisfy: -2<R3/R4<1.

In a possible implementation manner, the curvature radius R5 of the object-side surface of the third lens and the curvature radius R6 of the image-side surface of the third lens satisfy: 1<R5/R6<2.

In a possible implementation manner, the curvature radius R7 of the object-side surface of the fourth lens and the curvature radius R8 of the image-side surface of the fourth lens satisfy: 1<R7/R8<2.

In a possible implementation, the lens is used in depth detection.

Based on the above technical solution, the infrared imaging lens includes four lenses. By designing the focal power and shape of the four lenses, the focal length f of the lens, the maximum image height Y' on the imaging plane of the lens, and the longitudinal distance TTL of the lens along the optical axis meet the preset conditions, so that the lens has a large The field of view angle FOV and the smaller F-number improve the field of view and imaging accuracy of the infrared imaging lens.

Description of drawings

FIG. 1 is a schematic structural diagram of an infrared imaging module according to an embodiment of the present application.

FIG. 2 is a schematic diagram of imaging light by a lens in the infrared imaging module shown in FIG. 1 .

FIG. 3 is a schematic diagram of an infrared imaging lens according to an embodiment of the present application.

FIG. 4 is a schematic diagram of a layout of a lens according to an embodiment of the present application.

FIG. 5 is a schematic diagram of an astigmatic aberration curve of the lens shown in FIG. 4 .

FIG. 6 is a schematic diagram of a distortion curve of the lens shown in FIG. 4 .

FIG. 7 is a schematic diagram of a contraction curve of the imaging quality of the lens shown in FIG. 4 .

FIG. 8 is a schematic diagram of another layout of a lens according to an embodiment of the present application.

FIG. 9 is a schematic diagram of an astigmatic aberration curve of the lens shown in FIG. 8 .

FIG. 10 is a schematic diagram of a distortion curve of the lens shown in FIG. 8 .

FIG. 11 is a schematic diagram of a collection curve of the imaging quality of the lens shown in FIG. 8 .

FIG. 12 is a schematic diagram of another layout of the lens according to the embodiment of the present application.

FIG. 13 is a schematic diagram of an astigmatic aberration curve of the lens shown in FIG. 12 .

FIG. 14 is a schematic diagram of a distortion curve of the lens shown in FIG. 12 .

FIG. 15 is a schematic diagram of a collection curve of the imaging quality of the lens shown in FIG. 12 .

FIG. 16 is a schematic diagram of another layout of the lens according to the embodiment of the present application.

FIG. 17 is a schematic diagram of the astigmatism curve of the lens shown in FIG. 16 .

FIG. 18 is a schematic diagram of a distortion curve of the lens shown in FIG. 16 .

FIG. 19 is a schematic diagram of the yoke curve of the imaging quality of the lens shown in FIG. 16 .

detailed description

The technical solutions in the present application will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of an infrared imaging lens according to an embodiment of the present application. As shown in FIG. 1 , the infrared imaging module 100 includes an infrared imaging lens (hereinafter referred to as a lens) 110 , a lens barrel 120 , a bracket 130 , a filter 140 , a photosensitive chip 150 , a circuit board 160 and a reinforcing steel plate 170 .

The lens 110 is a signal collecting part, and is the core component of the infrared imaging module 100 , which may be an optical structure composed of a spherical surface or an aspherical surface, and is used to focus incident light onto the image sensor. The lens 110 may be formed by a combination of one or more lenses, and each lens may be, for example, injection-molded by using materials such as resin.

The lens barrel 120 (Barrel) is a non-light-absorbing support for fixing the lens 110 .

The bracket 130 (Holder) is a barrel-shaped structure with threads, and is mainly used to control the defocus and eccentricity of the lens 110 . The embodiment of the present application does not limit the manufacturing method of the structural member 130 , for example, it can be made of metal stamping.

The filter 140 (Filter) is an infrared band-pass filter, which is used to filter out light in non-target wavelength bands such as visible light and far-infrared. The filter 140 can be formed by, for example, evaporating an infrared radiation (Infrared Radiation, IR) material coating on a blue crystal substrate.

The photosensitive chip 150 is an integrated circuit composed of a photoelectric sensor, which can convert light energy into electrical signals and output them, and is used in conjunction with the lens 110 .

The circuit board 160 is a device that connects the circuit of the photosensitive chip 150 with the circuit of the electronic device, and may be, for example, a flexible printed circuit (Flexible Printed Circuit, FPC).

The reinforcing steel plate 170 is used to increase the mechanical strength and reliability of the chip module. The embodiment of the present application does not limit the composition of the reinforcing steel plate, for example, it may be composed of a steel sheet or a printed circuit board (Printed Circuit Board, PCB).

It should be understood that the structure of the infrared imaging lens 100 shown in FIG. 1 is only an example, and the embodiment of the present application mainly improves the lens 110 therein, and does not limit the positions and parameters of other structures and devices.

As shown in FIG. 2, taking the light in the central field of view as an example, the light emitted by the object point on the object side is converged by the lens 110, and the converged light is filtered by the filter 140 to filter out the signal interference of the non-target band, and finally The photosensitive chip 150 converges into one image point. By imaging different object points on the object side one by one, an imaging picture can be finally obtained on the photosensitive chip 150 .

The embodiment of the present application designs an infrared imaging lens, which has a larger field of view and a smaller F-number, thus enabling the infrared imaging lens to have better imaging performance.

For better understanding, firstly, the parameter indicators designed in the embodiments of the present application that can be used to evaluate the performance of the infrared imaging lens are briefly introduced.

Field of View (FOV): It is used to characterize the field of view of the lens. In the case of the same lens size, the larger the FOV of the lens, the more information that the lens can obtain, that is, the lens can obtain the information of a larger area. more information.

Aperture value or F-number (f-number, Fno): the reciprocal of the relative aperture of the lens, which is used to characterize the amount of light entering the photosensitive chip through the lens. The smaller the F-number, the greater the amount of light entering the lens.

TV distortion: used to measure the degree of visual distortion of the image. It can be understood that the smaller the TV distortion, the better the imaging effect.

The lens 110 in the infrared imaging lens module 100 shown in FIG. 1 is shown in FIG. 3 . The lens 110 includes a first lens 111 , a second lens 112 , a third lens 113 and a fourth lens arranged in sequence from the object side to the image side lens 114 .

The first lens 111 is a lens with positive refractive power. The first lens 111 has a convex surface on the paraxial object side and a concave surface on the paraxial image side. At least one of the two surfaces of the first lens 111 is Aspherical.

The second lens 112 is a lens with positive refractive power, the second lens 112 is a convex surface or a plane on the paraxial object side, and at least one of the two surfaces of the second lens 112 is an aspheric surface;

The third lens 113 is a lens with positive refractive power. The third lens 113 has a concave surface on the paraxial object side and a convex surface on the paraxial image side. At least one of the two surfaces of the third lens 113 is Aspherical;

The fourth lens 114 is a lens with negative refractive power, the fourth lens 114 is convex on the paraxial object side, and is concave on the paraxial image side, and at least one of the two surfaces of the fourth lens 114 is aspherical.

It should be understood that "the lens is on the paraxial object side" described in the embodiments of the present application can also be expressed as "the paraxial area of the lens on the object side", for example, the first lens 111 is on the paraxial object side One surface is convex, that is, the paraxial region of the first lens 111 on the object side surface is convex.

It should also be understood that the "paraxial" or "paraxial region" of the lens refers to the region of the paraxial light having an included angle θ with the optical axis, where θ satisfies: θ≈sinθ. For example, θ may be less than 5°.

For example, the first lens 111 , the second lens 112 , the third lens 113 and the fourth lens 114 can be injection-molded by using resin materials or other plastic materials, which are not limited here.

The parameters of the lens 110 satisfy predetermined conditions such that the FOV of the lens 110 is greater than the first threshold and less than the second threshold, and the F-number of the lens 110 is less than the third threshold.

The parameters of the lens 110 include at least two of the following: the focal length f of the lens 110 , the maximum image height Y′ on the imaging plane of the lens 110 , and the distance between the object side of the first lens 111 and the imaging plane of the lens 110 The distance is the total longitudinal length (Total Trace Length, TTL).

In the embodiment of the present application, the lens includes four lenses. By designing the power and shape of the four lenses, the f, Y' and TTL of the lens meet the preset conditions, so as to have a large field of view FOV and a small F number without increasing the infrared The vertical space occupied by the imaging lens when assembled in the electronic equipment improves the field of view and imaging accuracy of the infrared imaging lens while meeting the increasingly tight size constraints of the electronic equipment.

For example, the infrared imaging lens can be applied to depth detection, so as to realize the depth detection of the target.

Further, the infrared imaging lens can be applied to, for example, the scheme in which the transmitting end is a surface light source, that is, when the infrared imaging lens is used as the receiving end (RX end), its corresponding transmitting end (TX end) can be a surface light source infrared light module. , such as an infrared light module or a near-infrared light module composed of a vertical cavity surface emitting laser (Vertical-Cavity Surface-Emitting Laser, VCSEL) light-emitting chip, a collimator (Collimator) and a diffuser (Diffuser).

The f, Y' and TTL of the lens directly affect the FOV and F number of the lens, and f, Y' and TTL also affect each other, so by controlling the preset relationship between f, Y' and TTL, it is possible to make The lens 110 has a larger FOV and a smaller F-number to meet the imaging requirements of the lens, further enabling the photosensitive chip 150 to obtain more light carrying target information, maximizing the use of the effective photosensitive area of the photosensitive chip 150, thereby improving the Imaging resolution, improve imaging accuracy.

The preset conditions satisfied by f, Y' and TTL of the lens, for example, may include: 0<|Y'/(f*TTL)|<0.5 and/or 0.48<Y'/TTL<0.5.

When the above parameters of the lens 110 satisfy the preset condition, the FOV of the lens 110 may be greater than the first threshold and less than the second threshold, and the F-number of the lens 110 may be less than the third threshold. The first threshold may be, for example, 65 degrees, the second threshold may be, for example, 80 degrees, and the third threshold may be, for example, 1.25. When 65°<FOV<80°, a balance between the accuracy requirements of depth detection and the field of view requirements can be achieved. When the F number is less than 1.25, the detection of weak signals can be realized and the exposure time can be shortened.

Further, when the above parameters of the lens 110 satisfy the preset condition, the TV distortion of the lens 110 can be made smaller than the fourth threshold. The fourth threshold may be, for example, 5%. When the TV distortion is less than 5%, the depth distortion of the target can be avoided.

In addition, based on the above design, the size (TTL) of the infrared imaging lens may be smaller than a fifth threshold, for example, 4.1 mm.

The above describes the conditions that the parameters of the lens 110 should meet as a whole, and the following describes the respective parameter designs of the first lens 111 , the second lens 112 , the third lens 113 and the fourth lens 114 in the lens 110 . When the parameters of each lens satisfy some or all of the following conditions, the FOV and F-number of the lens 110 may satisfy 65°<FOV<80 and F-number<1.25, respectively.

For the first lens 111 , optionally, _{a certain relationship is satisfied between the focal length f 1} of the first lens 111 and the radius of curvature of the first lens 111 . For example, the relationship between the focal length f ₁ and the radius of curvature R1 of the object-side surface of the first lens 111 satisfies 0<f ₁ /R1<30; for another example, the difference between the focal length f ₁ and the radius of curvature R2 of the image-side surface of the first lens 111 The time satisfies 0<f ₁ /R2<35.

For the second lens 112 , optionally, _{a certain relationship is satisfied between the focal length f 2} of the second lens 112 and the radius of curvature of the second lens 112 . For example, the relationship between the focal length f ₂ and the radius of curvature R3 of the object-side surface of the second lens 112 satisfies 0<f ₂ /R3<2; for another example, the difference between the focal length f ₂ and the radius of curvature R4 of the image-side surface of the second lens 112 The time satisfies -1<f ₂ /R4<1.

For the third lens 113 , optionally, _{a certain relationship is satisfied between the focal length f 3} of the third lens 113 and the curvature radius of the third lens 113 . For example, the relationship between the focal length f ₃ and the curvature radius R5 of the object side surface of the third lens 113 satisfies -5<f ₃ /R5<-2; for another example, the focal length f ₃ and the curvature radius of the image side surface of the third lens 113 -6<f ₃ /R6<-2 is satisfied between R6.

For the fourth lens 114 , optionally, _{a certain relationship is satisfied between the focal length f 4} of the fourth lens 114 and the curvature radius of the fourth lens 114 . For example, to meet -6 <f ₄ / R7 <0 R7 between the focal length f ₄ of the fourth lens 114 and the object-side radius of curvature of one surface; and a radius of curvature e.g., f ₄ the focal length of the lens and the image side of the fourth side 114 of R8 Between -10<f ₄ /R8<-2.

For each lens, there are two surfaces close to the object side and the image side, respectively, and optionally, a certain relationship is satisfied between the radii of curvature of the two surfaces. For example, the curvature radius R1 of the object side surface of the first lens 111 and the curvature radius R2 of the image side surface of the first lens 111 satisfy 0<R1/R2<2; for another example, the object side surface of the second lens 112 The relationship between the curvature radius R3 and the curvature radius R4 of the image side surface of the second lens 112 satisfies -2<R3/R4<1; for another example, the curvature radius R5 of the object side surface of the third lens 113 and the image of the third lens 113 The curvature radius R6 of the side surface satisfies 1<R5/R6<2; for another example, the curvature radius R7 of the object side surface of the fourth lens 114 and the curvature radius R8 of the image side surface of the fourth lens 114 satisfy 1< R7/R8<2.

It can be seen that by designing the respective focal lengths and curvature radii of the four lenses, the FOV of the lens 110 can meet the imaging requirements, and the length of the lens 110 can be effectively reduced, the aberration can be reduced, and the maximum imaging surface Y' can be increased, thereby effectively improving the lens. 110 image quality. It can also reduce the sensitivity of the lens and improve the product yield.

In the embodiment of the present application, the first lens 111 , the second lens 112 and the third lens 113 are lenses with positive refractive power, and the fourth lens 114 is a lens with negative refractive power. Specifically, for the power distribution among the lenses, the following relationship exists between the respective focal lengths of the first lens 111, the second lens 112, the third lens 113, and the fourth lens 114 and the focal length f of the lens 110, thereby reducing The depth of field of the lens 110 improves the imaging quality of a specific surface, namely the object surface.

_{For example, the focal length f 1 of the} first lens 111 and the focal length f of the lens 110 satisfy 1<f ₁ /f<20; for another example, the focal length f _{2 of the} second lens 112 and the focal length f of the lens 110 satisfy 0< f ₂ /f<5; for another example, the focal length f _{3 of the} third lens 113 and the focal length f of the lens 110 satisfy 0<f ₃ /f<2; for another example, the focal length f _{4 of the} fourth lens 114 and the lens 110 satisfy The focal lengths f satisfy -5<f ₄ /f<0.

In order to make the structure of the lens 110 more sturdy and improve the service life of the lens 110, the center thickness of the first lens 111, the second lens 112, the third lens 113 and the fourth lens 114, that is, the thickness along the optical axis direction, can also be adjusted. design.

For example, the central thickness CT1 of the first lens 111 and the central thickness CT2 of the second lens 112 satisfy 0.8<CT1/CT2<2; for another example, the central thickness CT2 of the second lens 112 and the central thickness CT3 of the third lens 113 The relationship satisfies 0.5<CT2/CT3<2; for another example, the center thickness CT3 of the third lens 113 and the center thickness CT4 of the fourth lens 114 satisfy 0.5<CT3/CT4<2.

In addition, in order to meet the dispersion requirements and reduce the production cost, as well as provide a suitable phase difference balance, the refractive index and dispersion of the materials of the first lens 111 , the second lens 112 , the third lens 113 and the fourth lens 114 can also be adjusted. coefficients are designed.

For example, the refractive index n1>1.6 of the material of the first lens 111, the dispersion coefficient v1>20.0 of the material of the first lens 111; for another example, the refractive index n2>1.6 of the material of the second lens 112, the material of the second lens 112 For another example, the refractive index of the material of the third lens 113 is n3>1.6, and the dispersion coefficient of the material of the third lens 113 is v3>20.0; for another example, the refractive index of the material of the fourth lens 114 is n4> 1.5, the dispersion coefficient v4 of the material of the fourth lens 114 is >20.0.

Optionally, in some implementations, the lens 110 further includes a diaphragm 115, which may also be referred to as an aperture. The diaphragm 115 may be disposed, for example, on the side of the first lens 111 close to the object side.

The aperture 115 can be used to adjust the size of the light or imaging range. By setting the aperture 115 to adjust the light or imaging range, the light carrying the target information can be imaged on the photosensitive chip to the greatest extent, so that the photosensitive chip can obtain more The target information can further improve the analytical power of the depth detection of the target.

In this embodiment of the present application, various components in the lens 110 can be controlled by controlling physical parameters such as the radius of curvature, thickness, material, effective diameter, and conic coefficient of the first lens, the second lens, and the diaphragm, and/or the The even-order term in the aspheric high-order term coefficient of the aspheric lens in the lens 110, etc., make the parameters of the lens 110 meet the above-mentioned preset relationship, and then make the FOV of the lens 110 greater than 65°, TV distortion less than 5%, F The number is less than 1.25. Hereinafter, Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4 are used as examples to specifically describe the form of the lens 110 in the embodiments of the present application.

Example 1

The lens 110 includes four lenses, and the layout of each lens is shown in FIG. 4 , wherein, from the object side to the image side, the order is: diaphragm 115 , first lens 111 , second lens 112 , third lens 113 , the fourth lens 114 , the filter 140 and the imaging surface 116 .

For the convenience of distinction and description, in the order from the object side to the image side, the object plane is denoted as S0, the surface of the diaphragm 115 is denoted as S1, the two surfaces of the first lens 111 are denoted as S2 and S3, respectively, and the second The two surfaces of the lens 112 are denoted as S4 and S5 respectively, the two surfaces of the third lens 113 are denoted as S6 and S7 respectively, the two surfaces of the fourth lens 114 are denoted as S8 and S9 respectively, and the two surfaces of the filter 140 are denoted as S8 and S9 respectively. The surfaces are denoted as S10 and S11, respectively, and the imaging surface 116 is denoted as S12.

Further, by setting the focal length, radius of curvature, and center thickness of each lens in the lens 110, at least one of the radius of curvature, thickness, material, effective diameter, and conic coefficient of each surface of the lens 110, and the The aspherical high-order coefficient of the spherical lens, so that the FOV and F-number of the lens 110 meet the requirements.

In Example 1, the settings of the focal length, curvature radius, and center thickness of each lens are shown in Table 1. The settings of the curvature radius, thickness, material (n, v), effective diameter, and conic coefficient of each surface in S1 to S12 are shown in Table 2. The settings of the aspheric high-order coefficients A2, A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the aspheric surfaces in S1 to S12 are shown in Table 3, where the coefficients of A2 are all 0.

Table 1

Table 2

surface	surface type	Radius of curvature	thickness	Material	Effective diameter	Conic factor
S0	object plane	unlimited	2500			0.000
S1	diaphragm	unlimited	-0.206		1.210	0.000
S2	Aspherical	1.875	0.608	1.64, 26.3	1.212	-0.134
S3	Aspherical	1.741	0.227		1.237	-0.03
S4	Aspherical	1.702	0.553	1.64, 26.3	1.194	-0.217
S5	Aspherical	15.97	0.636		1.243	-158.8
S6	Aspherical	-1.310	0.384	1.64, 26.3	1.198	-0.899
S7	Aspherical	-0.977	0.030		1.216	-0.958
S8	Aspherical	1.483	0.424	1.54, 56	1.535	-5.283
S9	Aspherical	0.889	0.281		1.759	-0.918
S10	spherical	unlimited	0.210	1.51, 64.2	1.828	0.000
S11	spherical	unlimited	0.642		1.870	0.000
S12	image plane	unlimited	0.000		2.072	0.000

table 3

Based on the parameters shown in Table 1, Table 2 and Table 3, the parameters of the lens 110 shown in Embodiment 1 can be determined as follows: TTL=4.0mm, f=2.797mm, F-number=1.14, FOV=70°.

FIG. 5 shows the aberration curve of the astigmatism of the lens 110; FIG. 6 shows the aberration curve of the distortion of the lens 110; Transfer Function, MTF) curve. From the simulation diagrams shown in FIGS. 5 to 7 , it can be concluded that when the parameters TTL, f, and Y′ of the lens 110 meet the above preset conditions, the lens 110 has a larger FOV, a smaller working F number, As well as less TV distortion, and the lens performs better.

Example 2

The lens 110 includes four lenses, and the layout of each lens is shown in FIG. 8 , wherein, from the object side to the image side, the order is: diaphragm 115 , first lens 111 , second lens 112 , third lens 113 , the fourth lens 114 , the filter 140 and the imaging surface 116 .

For the convenience of distinction and description, in the order from the object side to the image side, the object plane is denoted as S0, the surface of the diaphragm 115 is denoted as S1, the two surfaces of the first lens 111 are denoted as S2 and S3, respectively, and the second The two surfaces of the lens 112 are denoted as S4 and S5 respectively, the two surfaces of the third lens 113 are denoted as S6 and S7 respectively, the two surfaces of the fourth lens 114 are denoted as S8 and S9 respectively, and the two surfaces of the filter 140 are denoted as S8 and S9 respectively. The surfaces are denoted as S10 and S11, respectively, and the imaging surface 116 is denoted as S12.

Further, by setting the focal length, radius of curvature, and center thickness of each lens in the lens 110, at least one of the radius of curvature, thickness, material, effective diameter, and conic coefficient of each surface of the lens 110, and the The aspherical high-order coefficient of the spherical lens, so that the FOV and F-number of the lens 110 meet the requirements.

In Example 2, the settings of the focal length, curvature radius, and center thickness of each lens are shown in Table 4. The settings of the curvature radius, thickness, material (n, v), effective diameter, and conic coefficient of each surface in S1 to S12 are shown in Table 5. The settings of the aspheric high-order term coefficients A2, A4, A6, A8, A10, A12, A14, and A16 of the aspheric surfaces in S1 to S12 are shown in Table 6, where the coefficients of A2 are all 0.

Table 4

table 5

surface	surface type	Radius of curvature	thickness	Material	Effective diameter	Conic factor
S0	object plane	unlimited	520.000			0.000
S1	diaphragm	unlimited	-0.039		1.216	0.000
S2	Aspherical	2.053	0.508	1.642, 26.3	1.240	-4.429
S3	Aspherical	4.235	0.282		1.240	-4.537
S4	Aspherical	5.368	0.520	1.642, 26.3	1.347	12.964
S5	Aspherical	-10.092	0.569		1.347	52.040
S6	Aspherical	-1.332	0.435	1.642, 26.3	1.176	-0.144
S7	Aspherical	-1.010	0.071		1.176	-4.754
S8	Aspherical	1.289	0.374	1.545, 56.0	1.690	-4.425
S9	Aspherical	0.797	0.347		1.690	-4.510
S10	spherical	unlimited	0.210	1.51, 64.2	1.786	0.000
S11	spherical	unlimited	0.645		1.786	0.000
S12	image plane	unlimited	0.000		1.960	0.000

Table 6

surface	A4	A6	A8	A10	A12	A14	A16
S2	2.71E-03	-7.66E-03	-1.30E-02	-2.09E-02	1.17E-02	-1.73E-03	7.37E-04
S3	-4.78E-02	-3.87E-02	7.54E-03	-2.13E-02	2.14E-02	-5.87E-03	4.53E-04
S4	-2.35E-02	1.84E-02	-1.36E-01	2.60E-01	-2.35E-01	1.09E-01	-2.11E-02
S5	-1.36E-02	9.42E-02	-1.48E-01	1.51E-01	-8.71E-02	2.20E-02	-1.71E-03
S6	2.42E-01	-1.78E-01	1.09E-01	6.65E-02	-7.47E-02	1.48E-02	8.68E-04
S7	-1.54E-01	2.52E-01	-2.95E-01	2.51E-01	-8.21E-02	-5.48E-03	7.37E-03
S8	-1.50E-01	4.95E-02	-1.60E-02	-4.71E-03	2.70E-03	5.32E-05	3.09E-05
S9	-6.40E-02	3.26E-03	5.82E-04	-2.51E-03	1.02E-03	-2.40E-04	2.85E-05

Based on the parameters shown in Table 4, Table 5 and Table 6, the parameters of the lens 110 shown in Embodiment 2 can be determined as follows: TTL=4.0mm, f=2.788mm, F-number=1.14, FOV=71°.

FIG. 9 shows the astigmatism curve of the lens 110 ; FIG. 10 shows the distortion curve of the lens 110 ; FIG. 11 shows the blur curve of the imaging quality of the lens 110 , that is, the MTF curve. From the simulation diagrams shown in FIGS. 9 to 11 , it can be concluded that when the parameters f, Y′ and TTL of the lens 110 meet the above preset conditions, the lens 110 has a larger FOV, a smaller working F number, As well as less TV distortion, and the lens performs better.

Example 3

The lens 110 includes four lenses, and the layout of each lens is shown in FIG. 12 , wherein, from the object side to the image side, the order is: diaphragm 115 , first lens 111 , second lens 112 , third lens 113 , the fourth lens 114 , the filter 140 and the imaging surface 116 .

For the convenience of distinction and description, in the order from the object side to the image side, the object plane is denoted as S0, the surface of the diaphragm 115 is denoted as S1, the two surfaces of the first lens 111 are denoted as S2 and S3, respectively, and the second The two surfaces of the lens 112 are denoted as S4 and S5 respectively, the two surfaces of the third lens 113 are denoted as S6 and S7 respectively, the two surfaces of the fourth lens 114 are denoted as S8 and S9 respectively, and the two surfaces of the filter 140 are denoted as S8 and S9 respectively. The surfaces are denoted as S10 and S11, respectively, and the imaging surface 116 is denoted as S12.

Further, by setting the focal length, curvature radius, and center thickness of each lens in the lens 110, at least one of the curvature radius, thickness, material (n, v), effective diameter, and conic coefficient of each surface of the lens 110, and The coefficient of the aspheric high-order term of the aspheric lens in the lens 110 is to make the FOV and F number of the lens 110 meet the requirements.

In Example 3, the settings of the focal length, curvature radius, and center thickness of each lens are shown in Table 7. The settings of the curvature radius, thickness, material, effective diameter, and cone coefficient of each surface in S1 to S12 are shown in Table 8. The settings of the aspheric higher-order term coefficients A2, A4, A6, A8, A10, A12, A14, and A16 of the aspheric surfaces in S1 to S12 are shown in Table 9, where the coefficients of A2 are all 0.

Table 7

Table 8

surface	surface type	Radius of curvature	thickness	Material	Effective diameter	Conic factor
S0	object plane	unlimited	500.000			0.000
S1	diaphragm	unlimited	-0.201		1.173	0.000
S2	Aspherical	2.057	0.660	1.642, 26.3	1.173	-1.461
S3	Aspherical	8.299	0.433		1.192	-9.417
S4	Aspherical	18.892	0.353	1.642, 26.3	1.191	57.839
S5	Aspherical	-13.988	0.396		1.285	110.958
S6	Aspherical	-1.160	0.458	1.642, 26.3	1.250	-0.514
S7	Aspherical	-0.963	0.036		1.259	-4.033
S8	Aspherical	1.424	0.490	1.642, 26.3	1.843	-2.725
S9	Aspherical	0.975	0.318		1.788	-5.553
S10	spherical	unlimited	0.210	1.51, 64.2	1.808	0.000
S11	spherical	unlimited	0.653		1.836	0.000

S12

image plane

unlimited

0.000

1.978

0.000

Table 9

surface	A4	A6	A8	A10	A12	A14	A16
S2	-3.06E-03	-1.06E-02	3.08E-03	-2.51E-02	1.75E-02	-6.81E-03	-2.61E-05
S3	-4.79E-02	-2.61E-02	5.07E-03	-3.65E-02	3.71E-02	-1.13E-02	9.32E-05
S4	-8.22E-02	1.25E-02	-2.36E-01	4.19E-01	-3.83E-01	2.11E-01	-5.19E-02
S5	-2.11E-02	4.53E-02	-1.91E-01	2.45E-01	-1.49E-01	4.06E-02	-3.82E-03
S6	3.23E-01	-2.66E-01	1.33E-01	1.08E-01	-1.22E-01	2.76E-02	1.42E-03
S7	-1.94E-01	3.42E-01	-4.41E-01	3.70E-01	-1.30E-01	5.13E-03	5.70E-03
S8	-1.47E-01	7.03E-02	-2.27E-02	-2.37E-03	4.04E-03	-9.91E-04	7.76E-05
S9	-2.88E-02	-1.36E-02	1.22E-02	-5.82E-03	1.30E-03	-1.49E-04	7.88E-06

Based on the parameters shown in Table 7, Table 8 and Table 9, the parameters of the lens 110 shown in Embodiment 3 can be determined as follows: TTL=4.0mm, f=2.743mm, F-number=1.13, FOV=71°.

FIG. 13 shows the astigmatism curve of the lens 110 ; FIG. 14 shows the distortion curve of the lens 110 ; FIG. 15 shows the blur curve of the imaging quality of the lens 110 , that is, the MTF curve. From the simulation diagrams shown in FIGS. 13 to 15 , it can be concluded that when the parameters f, Y′ and TTL of the lens 110 meet the above preset conditions, the lens 110 has a larger FOV, a smaller working F number, As well as less TV distortion, and the lens performs better.

Example 4

The lens 110 includes four lenses, and the layout of each lens is shown in FIG. 16 , wherein, from the object side to the image side, the order is: diaphragm 115 , first lens 111 , second lens 112 , third lens 113 , the fourth lens 114 , the filter 140 and the imaging surface 116 .

For the convenience of distinction and description, in the order from the object side to the image side, the object plane is denoted as S0, the surface of the diaphragm 115 is denoted as S1, the two surfaces of the first lens 111 are denoted as S2 and S3, respectively, and the second The two surfaces of the lens 112 are denoted as S4 and S5 respectively, the two surfaces of the third lens 113 are denoted as S6 and S7 respectively, the two surfaces of the fourth lens 114 are denoted as S8 and S9 respectively, and the two surfaces of the filter 140 are denoted as S8 and S9 respectively. The surfaces are denoted as S10 and S11, respectively, and the imaging surface 116 is denoted as S12.

Further, by setting the focal length, radius of curvature, and center thickness of each lens in the lens 110, at least one of the radius of curvature, thickness, material, effective diameter, and conic coefficient of each surface of the lens 110, and the The aspherical high-order coefficient of the spherical lens, so that the FOV and F-number of the lens 110 meet the requirements.

In Example 4, the settings of the focal length, curvature radius, and center thickness of each lens are shown in Table 10. The settings of the curvature radius, thickness, material (n, v), effective diameter, and conic coefficient of each surface in S1 to S12 are shown in Table 11. The settings of the aspheric higher-order term coefficients A2, A4, A6, A8, A10, A12, A14, and A16 of the aspheric surfaces in S1 to S12 are shown in Table 12, where the coefficient of A2 is 0.

Table 10

project	parameter value
f 1 /f	1.535
f 2 /f	3.145
f 3 /f	1.402
f 4 /f	-1.662
f 1 /R1	2.850
f 1 /R2	1.393
f 2 /R3	1.254
f 2 /R4	-0.335
f 3 / R5	-3.101
f 3 / R6	-4.187
f 4 / R7	-2.773
f 4 / R8	-4.845
CT1/CT2	1.711
CT2/CT3	1.004
CT3/CT4	0.882
R1/R2	0.489
R3/R4	-0.267
R5/R6	1.350
R7/R8	1.747
Y'/(f*TTL)	0.172

Table 11

surface	surface type	Radius of curvature	thickness	Material	Effective diameter	Conic factor
S0	object plane	unlimited	860.000			0.000
S1	diaphragm	unlimited	-0.526		1.231	0.000
S2	Aspherical	1.566	0.691	1.614, 26	1.231	-0.598
S3	Aspherical	3.203	0.574		1.146	5.478
S4	Aspherical	7.294	0.404	1.66, 20.4	0.973	34.279
S5	Aspherical	-27.332	0.393		1.078	-17.731
S6	Aspherical	-1.315	0.402	1.66, 20.4	1.103	0.319
S7	Aspherical	-0.974	0.028		1.264	-4.664
S8	Aspherical	1.743	0.456	1.66, 20.4	1.603	-6.529
S9	Aspherical	0.998	0.234		1.815	-6.080
S10	spherical	unlimited	0.210	1.51, 64.2	1.856	0.000
S11	spherical	unlimited	0.596		1.882	0.000
S12	image plane	unlimited	0.000		1.993	0.000

Table 12

surface	A4	A6	A8	A10	A12	A14	A16
S2	1.00E-02	1.40E-02	2.84E-02	-7.52E-02	6.41E-02	-1.89E-02	-3.47E-04
S3	-8.91E-03	-2.50E-02	4.15E-02	-1.11E-01	1.10E-01	-6.05E-02	1.13E-02
S4	-9.43E-02	2.81E-02	-5.00E-01	1.14E+00	-1.49E+00	9.65E-01	-2.36E-01
S5	-9.88E-02	9.38E-02	-4.94E-01	7.23E-01	-5.18E-01	1.93E-01	-3.04E-02
S6	2.60E-01	-5.54E-01	3.44E-01	4.31E-01	-3.94E-01	1.20E-02	4.45E-02
S7	-3.30E-01	5.21E-01	-9.42E-01	1.06E+00	-4.89E-01	4.33E-02	1.62E-02
S8	-2.32E-01	1.52E-01	-4.39E-02	-1.36E-02	1.30E-02	-3.12E-03	2.50E-04
S9	-1.06E-01	3.85E-02	1.56E-03	-1.14E-02	4.99E-03	-9.38E-04	7.07E-05

Based on the parameters shown in Table 10, Table 11 and Table 12, the parameters of the lens 110 shown in Embodiment 4 can be determined as follows: TTL=4.0mm, f=2.909mm, F-number=1.13, FOV=71°.

FIG. 17 shows the astigmatism curve of the lens 110; FIG. 18 shows the distortion curve of the lens 110; FIG. 19 shows the blur curve of the imaging quality of the lens 110, that is, the MTF curve. From the simulation diagrams shown in FIGS. 17 to 19 , it can be concluded that when the parameters f, Y′ and TTL of the lens 110 meet the above preset conditions, the lens 110 has a larger FOV, a smaller working F number, As well as less TV distortion, and the lens performs better.

It should be understood that if the positions corresponding to the parameters in Table 1 to Table 12 are blank, it means that there is no such parameter or the value of this parameter is 0.

To sum up, the infrared imaging lens of the embodiment of the present application adopts a 4P lens as the signal collection device, and the lens has a larger field of view FOV and a smaller F number, and will not increase the time when the infrared imaging lens is assembled in an electronic device. The occupied vertical space improves the field of view and imaging accuracy of the infrared imaging lens while meeting the increasingly tight size constraints of electronic equipment.

It should be noted that, on the premise of no conflict, each embodiment described in this application and/or the technical features in each embodiment can be arbitrarily combined with each other, and the technical solution obtained after the combination should also fall within the protection scope of this application .

It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art to better understand the embodiments of the present application, rather than limiting the scope of the embodiments of the present application, and those skilled in the art can Various improvements and modifications can be made, and these improvements or modifications all fall within the protection scope of the present application.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited to this. should be covered within the scope of protection of this application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims (30)

1. An infrared imaging lens is characterized in that it comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence from the object side to the image side, wherein:

   The first lens is a lens with positive refractive power, the first lens is convex on the paraxial object side, and is concave on the paraxial image side, and at least two surfaces of the first lens have a convex surface. One face is aspheric;

   The second lens is a lens with positive refractive power, and the object-side surface of the second lens is a convex surface or a plane surface, and at least one of the two surfaces of the second lens is an aspheric surface;

   The third lens is a lens with positive refractive power, and the third lens has a concave surface on the paraxial object side and a convex surface on the paraxial image side. At least two surfaces of the third lens have a concave surface. One face is aspheric;

   The fourth lens is a lens with negative refractive power, and the fourth lens has a convex surface on the paraxial object side and a concave surface on the paraxial image side. Among the two surfaces of the fourth lens, at least One face is aspheric;

   Wherein, the parameters of the lens satisfy predetermined conditions, so that the FOV of the lens is greater than a first threshold and less than a second threshold, and the F-number of the lens is less than a third threshold, wherein the lens's FOV The parameters include at least two of the following: the focal length f of the lens, the maximum image height Y' on the imaging plane of the lens, and the distance between the object side of the first lens and the imaging plane of the lens. Distance TTL.
2. The infrared imaging lens according to claim 1, wherein the predetermined conditions include:

   0<|Y’/(f*TTL)|<0.5; and/or,

   0.48<Y’/TTL<0.51.
3. The infrared imaging lens according to claim 1 or 2, wherein the first threshold is 65 degrees, and the second threshold is 80 degrees.
4. The infrared imaging lens according to any one of claims 1 to 3, wherein the third threshold is 1.25.
5. The infrared imaging lens according to any one of claims 1 to 4, wherein the TV distortion of the lens is less than a fourth threshold.
6. The infrared imaging lens according to claim 5, wherein the fourth threshold is 5%.
7. The infrared imaging lens according to any one of claims 1 to 6, wherein the central thickness CT1 of the first lens and the central thickness CT2 of the second lens satisfy: 0.8<CT1/CT2< 2.
8. The infrared imaging lens according to any one of claims 1 to 7, wherein the central thickness CT2 of the second lens and the central thickness CT3 of the third lens satisfy: 0.5<CT2/CT3< 2.
9. The infrared imaging lens according to any one of claims 1 to 8, wherein the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 0.5<CT3/CT4< 2.
10. The infrared imaging lens according to any one of claims 1 to 9, wherein the refractive index of the material of the first lens n ₁ >1.6, and the dispersion coefficient of the material of the first lens v ₁ >20.0 .
11. The infrared imaging lens according to any one of claims 1 to 10, wherein the refractive index of the material of the second lens n ₂ >1.6, and the dispersion coefficient of the material of the second lens v ₂ >20.0 .
12. The infrared imaging lens according to any one of claims 1 to 11, wherein the refractive index of the material of the third lens n ₃ >1.6, and the dispersion coefficient of the material of the third lens v ₃ >20.0 .
13. The infrared imaging lens according to any one of claims 1 to 12, wherein the refractive index of the material of the fourth lens n ₄ >1.5, the dispersion coefficient of the material of the fourth lens v ₄ >20.0 .
14. The infrared imaging lens according to any one of claims 1 to 13, wherein the focal length f _{1 of} the first lens and the focal length f of the lens satisfy: 1<f ₁ /f<20.
15. The infrared imaging lens according to any one of claims 1 to 14, wherein the focal length f _{2 of} the second lens and the focal length f of the lens satisfy: 0<f ₂ /f<5.
16. The infrared imaging lens according to any one of claims 1 to 15, wherein the focal length f _{3 of} the third lens and the focal length f of the lens satisfy: 0<f ₃ /f<2.
17. The infrared imaging lens according to any one of claims 1 to 16, wherein the focal length f _{4 of} the fourth lens and the focal length f of the lens satisfy: -5<f ₄ /f<0 .
18. According to an infrared imaging lens according to claim 17, characterized in that, between the first lens satisfies a focal length F ₁ side and the object-side radius of curvature of the first lens R1: 0 < f ₁ /R1<30.
19. The infrared imaging lens 1 according to claim 18, characterized in that, between the first lens satisfies a focal length F ₁ of the one side and the image side of the first lens radius of curvature R2: 0 < f ₁ /R2<35.
20. According to an infrared imaging lens according to claim 19, characterized in that, between the second lens satisfies a focal length f ₂ of the second lens and the object-side radius of curvature of one surface R3: 0 < f ₂ /R3<2.
21. According to an infrared imaging lens according to claim 20, characterized in that, between the second lens satisfies a focal length f ₂ of the lens and the image side of the second side of the radius of curvature R4: -1 <f ₂ /R4<1.
22. Infrared imaging lens 1 according to any of 21-1 claim, characterized in that, between the third lens satisfies a focal length f ₃ of the third lens and the object-side radius of curvature of one surface R5: -5 <f ₃ /R5<-2.
23. According to an infrared imaging lens according to claim 22, characterized in that, between the third lens satisfies a focal length f ₃ of the third lens and the image-side radius of curvature of one surface R6: -6 <f ₃ /R6<-2.
24. According to an infrared imaging lens 23 to any one of the preceding claims, wherein said fourth lens satisfies R7 between the focal length f ₄ of the fourth lens and the object-side radius of curvature of one surface: -6 <f ₄ /R7<0.
25. According to an infrared imaging lens according to claim 24, characterized in that, to meet the R8 of the fourth lens between the focal length f ₄ of the fourth lens and the image-side radius of curvature of one surface: -10 <f ₄ /R8<-2.
26. The infrared imaging lens according to any one of claims 1 to 25, wherein the curvature radius R1 of the object side surface of the first lens is between the curvature radius R2 of the image side surface of the first lens Satisfy: 0<R1/R2<2.
27. The infrared imaging lens according to any one of claims 1 to 26, wherein the curvature radius R3 of the object side surface of the second lens is between the curvature radius R4 of the image side surface of the second lens Satisfy: -2<R3/R4<1.
28. The infrared imaging lens according to any one of claims 1 to 27, wherein the curvature radius R5 of the object side surface of the third lens is between the curvature radius R6 of the image side surface of the third lens Satisfy: 1<R5/R6<2.
29. The infrared imaging lens according to any one of claims 1 to 28, wherein the curvature radius R7 of the object side surface of the fourth lens is between the curvature radius R8 of the image side surface of the fourth lens Satisfy: 1<R7/R8<2.
30. The infrared imaging lens according to any one of claims 1 to 29, wherein the infrared imaging lens is used in depth detection.

Images