Infrared lens

Abstract

The utility model provides an infrared lens comprising an optical imaging lens group, and the optical imaging lens group is provided with 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 first lens is a glass spherical lens with negative focal power, the second lens is a glass spherical lens with positive focal power, the third lens is a glass spherical lens with positive focal power or negative focal power, and the fourth lens is a glass spherical lens with positive focal power or negative focal power; the focal power of the first lens, the second lens, the third lens and the fourth lens meets the following conditions:-1.47 < = phi 1 / phi < =-1.29; 0.97 < = phi 2 / phi < = 1.09; 0.31 < = phi 3 / phi < = 1.51; and phi 4 / phi is more than or equal to-0.75 and less than or equal to 1.02. Through reasonably arranging the combination of the focal powers of the plurality of lenses in the optical imaging lens group, the defects of volume limitation, low resolution, poor application effect, high cost and the like of the existing lens in the prior art are solved.

Description

Technical Field

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

[0002] With the rapid development of automobiles, people are paying more and more attention to driving safety. Car lenses are widely used in the front, sides, rear and inside of cars. Optical lenses require more miniaturization, high resolution and high stability. Nowadays, lenses still have volume limitations, low resolution, poor application effects and high costs. How to improve the performance of lenses and reduce costs has become the current market development trend. In view of this, the applicant has developed an infrared fixed-focus lens that achieves high resolution, small size and large target surface at a low cost. The aperture number can reach 2.0, the total length meets TTL≤12m, and can ensure that there is no out-of-focus under the use conditions of -40℃-95℃. Utility Model Content

[0003] The utility model proposes an infrared lens, which solves the defects of the existing lens in the prior art, such as volume limitation, low resolution, poor application effect, and high cost. The technical solution of the utility model is achieved as follows:

[0004] An infrared lens comprises an optical imaging lens group, wherein the optical imaging lens group is sequentially arranged along an optical axis from the object side to the image side with a first lens, a second lens, a third lens, and a fourth lens; the first lens is a glass spherical lens with negative optical power, the second lens is a glass spherical lens with positive optical power, the third lens is a glass spherical lens with positive optical power or negative optical power, and the fourth lens is a glass spherical lens with positive optical power or negative optical power; the optical powers of the first lens, the second lens, the third lens, and the fourth lens meet the following conditions:

[0005] -1.47≤φ1 / φ≤-1.29;

[0006] 0.97≤φ2 / φ≤1.09;

[0007] -0.31≤φ3 / φ≤1.51;

[0008] -0.75≤φ4 / φ≤1.02;

[0009] Among them, φ is the optical power of the entire optical imaging lens group, and φ1, φ2, φ3, and φ4 represent the optical power of the first lens to the fourth lens respectively.

[0010] As a preferred technical solution, the refractive index and dispersion coefficient of the first lens, the second lens, the third lens, and the fourth lens meet the following conditions:

[0011] n1≤1.73; n2≥1.85; 1.68≤n3≤1.92; 1.74≤n4≤2.01;

[0012] v1≥48.2; v2≤41; 31.1≤v3≤55.7; 17.8≤v4≤49.4;

[0013] Wherein, n1, n2, n3, and n4 represent the refractive indices of the first lens to the fourth lens respectively; v1, v2, v3, and v4 represent the dispersion coefficients of the first lens, the second lens, the third lens, and the fourth lens respectively.

[0014] As a preferred technical solution, the lens image plane diameter IC and entrance pupil diameter EPD meet the following conditions:

[0015] 1.20≤IC / EPD≤1.45.

[0016] As a preferred technical solution, the image plane radius IC and the total length TTL meet the following conditions:

[0017] 0.18≤IC / TTL≤0.20.

[0018] As a preferred technical solution, the back focus BFL of the lens and the total length TTL of the lens meet the following conditions:

[0019] BFL / TTL≥0.31.

[0020] Compared with the prior art, this solution has the following beneficial effects: by reasonably setting the combination of the optical focal lengths of multiple lenses in the optical imaging lens group, combined with a reasonable dispersion coefficient, lens image plane diameter IC and entrance pupil diameter EPD, image plane radius IC and total length TTL, lens back focus BFL and lens total length TTL, the effect of high resolution, small volume and large target surface can be achieved at a low cost, thus solving the defects of the current lenses in the prior art, such as volume limitation, low resolution, poor application effect and high cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a structural diagram of a lens in this embodiment 1;

[0023] Figure 2 is an FFT MTF diagram of a lens in this embodiment 1;

[0024] Figure 3 is a light fan diagram of a lens in this embodiment 1;

[0025] Figure 4 is a relative illumination diagram of a lens in this embodiment 1;

[0026] Figure 5 is a structural diagram of a lens in this embodiment 2;

[0027] Figure 6 is an FFT MTF diagram of a lens in this embodiment 2;

[0028] Figure 7 is a light fan diagram of a lens in this embodiment 2;

[0029] Figure 8 is a relative illumination diagram of a lens in this embodiment 2;

[0030] Fig. 9 is a structural diagram of a lens in this embodiment 3;

[0031] Fig.10 is an FFT MTF diagram of a lens in this embodiment 3;

[0032] Fig.11 is a light fan diagram of a lens in this embodiment 3;

[0033] Fig.12 This is a relative illumination diagram of a lens in this embodiment 3.

[0034] Description of reference numerals:

[0035] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens. DETAILED DESCRIPTION

[0036] The technical solution of the utility model will be described clearly and completely in conjunction with the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0037] See also Figure 1 , Figure 5 and Fig. 9The utility model discloses an infrared lens, comprising an optical imaging lens group, wherein the optical imaging lens group is sequentially arranged along the optical axis from the object side to the image side with a first lens 1, a second lens 2, a third lens 3, and a fourth lens 4; the first lens 1 is a glass spherical lens with negative optical power, the second lens 2 is a glass spherical lens with positive optical power, the third lens 3 is a glass spherical lens with positive optical power or negative optical power, and the fourth lens 4 is a glass spherical lens with positive optical power or negative optical power; the optical powers of the first lens, the second lens, the third lens, and the fourth lens meet the following conditions:

[0038] -1.47≤φ1 / φ≤-1.29;

[0039] 0.97≤φ2 / φ≤1.09;

[0040] -0.31≤φ3 / φ≤1.51;

[0041] -0.75≤φ4 / φ≤1.02;

[0042] Wherein, φ is the focal length of the entire optical imaging lens set, and φ1, φ2, φ3, and φ4 represent the focal lengths of the first lens to the fourth lens, respectively. As a preferred technical solution, the refractive index and dispersion coefficient of the first lens, the second lens, the third lens, and the fourth lens meet the following conditions:

[0043] n1≤1.73; n2≥1.85; 1.68≤n3≤1.92; 1.74≤n4≤2.01;

[0044] v1≥48.2; v2≤41; 31.1≤v3≤55.7; 17.8≤v4≤49.4;

[0045] In order to effectively reduce the sensitivity of assembly eccentricity, the refractive index and dispersion coefficient of the second lens satisfy: n2≥1.85, v2≤41.

[0046] Wherein, n1, n2, n3, and n4 represent the refractive indices of the first lens to the fourth lens respectively; v1, v2, v3, and v4 represent the dispersion coefficients of the first lens, the second lens, the third lens, and the fourth lens respectively.

[0047] As a preferred technical solution, the lens image plane diameter IC and entrance pupil diameter EPD meet the following conditions:

[0048] 1.20≤IC / EPD≤1.45. Meeting this condition enables the optical system to control the entrance pupil diameter of the optical system while satisfying the requirements of large image plane and high resolution, thereby ensuring sufficient light in the edge field of view of the imaging system and improving the brightness of the image plane.

[0049] The image radius IC and the total length TTL meet the following conditions:

[0050] 0.18≤IC / TTL≤0.20. When this condition is met, the optical system can have better imaging quality, clearer pictures and a smaller size.

[0051] The back focus BFL and the total length TTL of the lens meet the following conditions:

[0052] BFL / TTL≥0.31. Meeting this condition can ensure that there is enough installation space for the imaging sensor and the flat filter.

[0053] The beneficial effects are verified through three groups of embodiments that meet the above conditions. The parameter lists corresponding to the rights protection requirements of the three examples are as follows:

[0054]

[0055]

[0056] Example 1.

[0057] In this embodiment, the structure of the infrared lens is as follows: Figure 1 As shown, the optical physical parameters of the first lens to the fourth lens are as follows:

[0058]

[0059] pass Figure 2 FFT MTF diagram of Figure 3 The light fan diagram of Figure 4 From the relative illumination diagram, it can be concluded that the lens achieves high resolution, small size, large target surface, the aperture number can reach 2.0, the total length meets TTL≤12m, and can ensure no out-of-focus under the operating conditions of -40℃-95℃. It also has the advantage of low cost.

[0060] Example 2.

[0061] In this embodiment, the structure of the infrared lens is as follows: Figure 5 As shown, the optical physical parameters of the first lens to the fourth lens are as follows:

[0062]

[0063] pass Figure 6 FFT MTF diagram of Figure 7 The light fan diagram of Figure 8From the relative illumination diagram, it can be concluded that the lens achieves high resolution, small size, large target surface, the aperture number can reach 2.0, the total length meets TTL≤12m, and can ensure no out-of-focus under the operating conditions of -40℃-95℃. It also has the advantage of low cost.

[0064] Example 3.

[0065] In this embodiment, the structure of the infrared lens is as follows: Fig. 9 As shown, the optical physical parameters of the first lens to the fourth lens are as follows:

[0066]

[0067] pass Fig.10 FFT MTF diagram of Fig.11 The light fan diagram of Fig.12 From the relative illumination diagram, it can be concluded that the lens achieves high resolution, small size, large target surface, the aperture number can reach 2.0, the total length meets TTL≤12m, and can ensure no out-of-focus under the operating conditions of -40℃-95℃. It also has the advantage of low cost.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An infrared lens, characterized in that: The optical imaging lens group comprises a first lens, a second lens, a third lens and a fourth lens, which are arranged in sequence from the object side to the image side along the optical axis; the first lens is a glass spherical lens with negative optical power, the second lens is a glass spherical lens with positive optical power, the third lens is a glass spherical lens with positive optical power or negative optical power, and the fourth lens is a glass spherical lens with positive optical power or negative optical power; the optical power of the first lens, the second lens, the third lens and the fourth lens meets the following conditions: -1.47≤φ1 / φ≤-1.29; 0.97≤φ2 / φ≤1.09; -0.31≤φ3 / φ≤1.51; -0.75≤φ4 / φ≤1.02; Among them, φ is the optical power of the entire optical imaging lens group, and φ1, φ2, φ3, and φ4 represent the optical power of the first lens to the fourth lens respectively.

2. An infrared lens as claimed in claim 1, characterized in that: The refractive index and dispersion coefficient of the first lens, the second lens, the third lens and the fourth lens meet the following conditions: n1≤1.73; n2≥1.85; 1.68≤n3≤1.92; 1.74≤n4≤2.01; v1≥48.2; v2≤41; 31.1≤v3≤55.7; 17.8≤v4≤49.4; Wherein, n1, n2, n3, and n4 represent the refractive indices of the first lens to the fourth lens respectively; v1, v2, v3, and v4 represent the dispersion coefficients of the first lens, the second lens, the third lens, and the fourth lens respectively.

3. An infrared lens as claimed in claim 1, characterized in that: The lens image diameter IC and entrance pupil diameter EPD meet the following conditions: 1.20≤IC / EPD≤1.

45.

4. An infrared lens as claimed in claim 1, characterized in that: The image radius IC and the total length TTL meet the following conditions: 0.18≤IC / TTL≤0.

20.

5. An infrared lens as claimed in claim 1, characterized in that: The back focus BFL and the total length TTL of the lens meet the following conditions: BFL / TTL≥0.31.

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