Infrared lens

Abstract

The utility model relates to the technical field of vehicle-mounted lenses, in particular to an infrared lens, which comprises an optical imaging lens group and a diaphragm. The optical imaging lens group comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object space to an image space along an optical axis; the diaphragm is positioned between the first lens and the second lens; the first lens has positive focal power or negative focal power, the second lens has positive focal power, the third lens has positive focal power, and the fourth lens has negative focal power; the first lens and the second lens are respectively glass spherical lenses, and the third lens and the fourth lens are respectively glass aspheric lenses; the image surface diameter IC of the optical system and the total length TTL of the infrared lens meet the following condition: 0.53 < = IC / TTL < = 0.61. The optical system is novel in structure, has a large target surface and a small volume, and can ensure that the optical system has better imaging quality and clearer pictures.

Description

Technical Field

[0001] The utility model relates to the technical field of vehicle-mounted lenses, in particular to an infrared lens. Background Art

[0002] In recent years, with the different purposes and environments of use, the requirements for lenses have become more and more. How to improve the performance of lenses and reduce costs has become the current market development trend. The requirements for lenses in the automotive field are also getting higher and higher, mainly reflected in better imaging quality and smaller size. Therefore, developing an infrared fixed-focus lens that can ensure high-pixel imaging, miniaturization, and no out-of-focus under high and low temperature conditions has become an important issue in the industry. Summary of the invention

[0003] The utility model provides an infrared lens with novel structure and ingenious design. When the image plane diameter IC and the total length TTL of the infrared fixed-focus lens satisfy the condition of 0.53≤IC / TTL≤0.61, the optical system has better imaging quality and smaller volume.

[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0005] The utility model provides an infrared lens, which comprises an optical imaging lens group and an aperture; the optical imaging lens group 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 along the optical axis; the aperture is located between the first lens and the second lens; the first lens has positive focal power or negative focal power, the second lens has positive focal power, the third lens has positive focal power, and the fourth lens has negative focal power;

[0006] The first lens and the second lens are glass spherical lenses respectively, and the third lens and the fourth lens are glass aspherical lenses respectively; the image plane diameter IC of the optical system and the total length TTL of the infrared lens meet the following condition: 0.53≤IC / TTL≤0.61.

[0007] Wherein, the optical power of the first to fourth lenses meets the following conditions:

[0008] -0.625≤φ1 / φ≤0.742;

[0009] 0.602≤φ2 / φ≤1.512;

[0010] 0.279≤φ3 / φ≤0.568;

[0011] -0.351≤φ4 / φ≤-0.302;

[0012] Among them, φ is the optical power of the entire optical system, and φ1, φ2, φ3, and φ4 represent the optical powers of the first lens to the fourth lens in sequence.

[0013] Wherein, the refractive indexes of the first to fourth lenses satisfy the following conditions:

[0014] 1.91≤n1≤2.05;

[0015] 1.82≤n2≤1.94;

[0016] 1.80≤n3≤1.89;

[0017] 1.80≤n4≤1.89;

[0018] n1, n2, n3, and n4 represent the refractive indices of the first lens to the fourth lens, respectively.

[0019] Wherein, the dispersion coefficients of the first to fourth lenses satisfy the following conditions:

[0020] 17.5≤v1≤26.9;

[0021] 29.3≤v2≤35.5;

[0022] 37.1≤v3≤41.9;

[0023] 37.1≤v4≤41.9;

[0024] v1, v2, v3, and v4 represent the chromatic aberration coefficients of the first lens to the fourth lens, respectively.

[0025] Wherein, the aperture F of the infrared lens satisfies: 2.37≤F≤2.43.

[0026] The back focus BFL of the infrared lens and the total length TTL of the infrared lens satisfy the following condition: BFL / TTL≥0.28.

[0027] Beneficial effects of the utility model:

[0028] The utility model has a novel structure and ingenious design. When the image plane diameter IC and the total length TTL of the infrared lens meet the condition of 0.53≤IC / TTL≤0.61, the lens has better imaging quality and smaller volume, and the total length meets TTL≤8.5mm, which can ensure that there is no out-of-focus under high and low temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a structural diagram of an infrared lens in the first embodiment;

[0030] Figure 2is an FFT MTF diagram of an infrared lens in the first embodiment;

[0031] Figure 3 This is a light fan diagram of an infrared lens in the first embodiment;

[0032] Figure 4 is a spot diagram of an infrared lens in the first embodiment;

[0033] Figure 5 is a structural diagram of an infrared lens in the second embodiment;

[0034] Figure 6 is an FFT MTF diagram of an infrared lens in the second embodiment;

[0035] Figure 7 This is a light fan diagram of an infrared lens in the second embodiment;

[0036] Figure 8 is a spot diagram of an infrared lens in the second embodiment;

[0037] Fig. 9 is a structural diagram of an infrared lens in the third embodiment;

[0038] Fig.10 is an FFT MTF diagram of an infrared lens in the third embodiment;

[0039] Fig.11 This is a light fan diagram of an infrared lens in the third embodiment;

[0040] Fig.12 This is a spot diagram of an infrared lens in the third embodiment.

[0041] exist Figures 1 to 12 Reference numerals in the drawings include:

[0042] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Aperture; 6. Flat filter. DETAILED DESCRIPTION

[0043] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings, and the contents mentioned in the implementation modes are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0044] The present application embodiment provides an infrared lens, such as Figures 1 to 12As shown, it includes an optical imaging lens group and an aperture 5; the optical imaging lens group includes a first lens 1, a second lens 2, a third lens 3 and a fourth lens 4 arranged in sequence from the object side to the image side along the optical axis; the aperture is located between the first lens 1 and the second lens 2; the first lens 1 has positive focal power or negative focal power, the second lens 2 has positive focal power, the third lens 3 has positive focal power, and the fourth lens 4 has negative focal power; the first lens 1 and the second lens 2 are respectively glass spherical lenses, and the third lens 3 and the fourth lens 4 are respectively glass aspherical lenses; the image plane diameter IC of the optical system and the total length TTL of the infrared lens meet the following conditions: 0.53≤IC / TTL≤0.61.

[0045] In the embodiment of the present application, the optical focal lengths of the first lens 1 to the fourth lens 4 satisfy the following conditions: -0.625≤φ1 / φ≤0.742; 0.602≤φ2 / φ≤1.512; 0.279≤φ3 / φ≤0.568; -0.351≤φ4 / φ≤-0.302; φ is the optical focal length of the entire optical system, and φ1, φ2, φ3, and φ4 represent the optical focal lengths of the first lens to the fourth lens, respectively, in order.

[0046] In the embodiment of the present application, the refractive indices of the first lens to the fourth lens satisfy the following conditions: 1.91≤n1≤2.05; 1.82≤n2≤1.94; 1.80≤n3≤1.89; 1.80≤n4≤1.89; n1, n2, n3, n4 represent the refractive indices of the first lens to the fourth lens in order.

[0047] In the embodiment of the present application, the dispersion coefficients of the first to fourth lenses satisfy the following conditions: 17.5≤v1≤26.9; 29.3≤v2≤35.5; 37.1≤v3≤41.9; 37.1≤v4≤41.9; v1, v2, v3, v4 represent the dispersion coefficients of the first to fourth lenses in order.

[0048] In the embodiment of the present application, the aperture F of the infrared lens satisfies: 2.37≤F≤2.43.

[0049] In the embodiment of the present application, the back focus BFL of the infrared lens and the total length TTL of the infrared lens meet the following condition: BFL / TTL≥0.28. Specifically, under the above setting, it can be ensured that there is enough installation space for the imaging sensor and the flat filter 6.

[0050] Specifically, the embodiment of the present application has a novel structure and ingenious design. The lens has an aperture number of 2.4 at a low cost, achieves high pixels and a small size, and the total length satisfies TTL≤8.5mm, which can ensure that there is no out-of-focus under the operating conditions of -40℃-85℃.

[0051] This application uses parameters corresponding to three examples for demonstration, as shown in Table 1 below:

[0052]

[0053]

[0054] The aspheric formula is as follows:

[0055]

[0056] Among them, z represents the axial vector height of the aspheric surface in the Z direction; r represents the distance from the point on the aspheric surface to the optical axis; c represents the curvature of the fitted sphere, which is the inverse of the radius of curvature; k represents the fitted cone coefficient; A, B, C, D, E, F, and G represent the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order coefficients of the aspheric polynomial, respectively.

[0057] Embodiment 1:

[0058] In this embodiment, the optical physical parameters of the first lens to the fourth lens are shown in Table 2 below:

[0059]

[0060]

[0061]

[0062] Specifically, the surface numbers in Table 2 are numbered according to the surface order of each lens, wherein "S1" represents the object side surface of the first lens, "S2" represents the image side surface of the first lens, "S4" represents the object side surface of the second lens, "S5" represents the image side surface of the second lens, and so on; "S10" represents the object side surface of the flat filter, and "S11" represents the image side surface of the flat filter; the radius of curvature represents the degree of curvature of the lens surface, a negative value represents that the surface is bent toward the image side, and a positive value represents that the surface is bent toward the object side, wherein "INF" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, and the refractive index represents the ability of the material between the current surface and the next surface to deflect light; the dispersion coefficient represents the dispersion characteristics of the material between the current surface and the next surface to light.

[0063] Embodiment 2:

[0064] In this embodiment, the optical physical parameters of the first lens to the fourth lens are shown in Table 3 below:

[0065]

[0066]

[0067]

[0068] Specifically, the surface numbers in Table 3 are numbered according to the surface order of each lens, wherein "S1" represents the object side surface of the first lens, "S2" represents the image side surface of the first lens, "S4" represents the object side surface of the second lens, "S5" represents the image side surface of the second lens, and so on; "S10" represents the object side surface of the flat filter, and "S11" represents the image side surface of the flat filter; the radius of curvature represents the degree of curvature of the lens surface, a negative value represents that the surface is bent toward the image side, and a positive value represents that the surface is bent toward the object side, wherein "INF" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, and the refractive index represents the ability of the material between the current surface and the next surface to deflect light; the dispersion coefficient represents the dispersion characteristics of the material between the current surface and the next surface to light.

[0069] Embodiment three:

[0070] In this embodiment, the optical physical parameters of the first lens to the fourth lens are shown in Table 4 below:

[0071]

[0072]

[0073] Specifically, the surface numbers in Table 4 are numbered according to the surface order of each lens, wherein "S1" represents the object side surface of the first lens, "S2" represents the image side surface of the first lens, "S4" represents the object side surface of the second lens, "S5" represents the image side surface of the second lens, and so on; "S10" represents the object side surface of the flat filter, and "S11" represents the image side surface of the flat filter; the radius of curvature represents the degree of curvature of the lens surface, a negative value represents that the surface is bent toward the image side, and a positive value represents that the surface is bent toward the object side, wherein "INF" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, and the refractive index represents the ability of the material between the current surface and the next surface to deflect light; the dispersion coefficient represents the dispersion characteristics of the material between the current surface and the next surface to light.

[0074] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Although the utility model is disclosed as a preferred embodiment as above, it is not used to limit the utility model. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content disclosed above without departing from the scope of the technical solution of the utility model. However, any simple modification, equivalent change and modification made to the above embodiments according to the technology of the utility model, which does not depart from the content of the technical solution of the utility model, belongs to the scope of the technical solution of the utility model.

Claims

1. An infrared lens, characterized in that: The optical imaging lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence from the object side to the image side along the optical axis; the aperture is located between the first lens and the second lens; the first lens has positive or negative focal power, the second lens has positive focal power, the third lens has positive focal power, and the fourth lens has negative focal power; The first lens and the second lens are glass spherical lenses respectively, and the third lens and the fourth lens are glass aspherical lenses respectively; the image plane diameter IC of the optical system and the total length TTL of the infrared lens meet the following condition: 0.53≤IC / TTL≤0.

61.

2. An infrared lens according to claim 1, characterized in that: The optical power of the first to fourth lenses meets the following conditions: -0.625≤φ1 / φ≤0.742; 0.602≤φ2 / φ≤1.512; 0.279≤φ3 / φ≤0.568; -0.351≤φ4 / φ≤-0.302; Among them, φ is the optical power of the entire optical system, and φ1, φ2, φ3, and φ4 represent the optical powers of the first lens to the fourth lens in sequence.

3. The infrared lens according to claim 1, characterized in that: The refractive indexes of the first to fourth lenses satisfy the following conditions: 1.91≤n1≤2.05； 1.82≤n2≤1.94； 1.80≤n3≤1.89； 1.80≤n4≤1.89； n1, n2, n3, and n4 represent the refractive indices of the first lens to the fourth lens, respectively.

4. The infrared lens according to claim 1, characterized in that: The dispersion coefficients of the first to fourth lenses satisfy the following conditions: 17.5≤v1≤26.9； 29.3≤v2≤35.5； 37.1≤v3≤41.9； 37.1≤v4≤41.9； v1, v2, v3, and v4 represent the chromatic aberration coefficients of the first lens to the fourth lens, respectively.

5. The infrared lens according to claim 1, characterized in that: The aperture F of the infrared lens satisfies: 2.37≤F≤2.43。 6. The infrared lens according to claim 1, characterized in that: The back focus BFL of the infrared lens and the total length TTL of the infrared lens meet the following conditions: BFL / TTL≥0.28.

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