High-pixel infrared optical system and camera module for its application

Abstract

The embodiment of the present invention discloses a high-pixel infrared optical system, which includes: a first lens, a second lens, a third lens, and a fourth lens in sequence from the object plane to the image plane along the optical axis; the object plane side of the first lens is convex, the image plane side is concave, and its optical focal length is negative; the object plane side of the second lens is convex, the image plane side is concave, and its optical focal length is positive; the object plane side of the third lens is concave, the image plane side is convex, and its optical focal length is positive; the object plane side of the fourth lens is convex, and the image plane side is concave. On the other hand, the embodiment of the present invention also provides a camera module. The optical system and camera module of the embodiment of the present invention are mainly composed of 4 lenses, with a small number of lenses and a simple structure; different lenses are combined with each other and the optical focal length is reasonably distributed, and have good performances such as large aperture, small distortion, high pixels, and very good heat elimination.

Description

Technical field:

[0001] The present invention relates to an optical system and a camera module using the same, in particular to a high-pixel infrared optical system and a camera module using the same. Background technology:

[0002] With the application of infrared imaging technology and the development of intelligent driving assistance systems, infrared lenses are increasingly used in the automotive field. However, traditional infrared lenses have the problem of a large number of lenses and a complex structure. Summary of the invention:

[0003] In order to overcome the problems of a large number of lenses and high cost in traditional infrared lenses, an embodiment of the present invention provides a high-pixel infrared optical system.

[0004] A high-pixel infrared optical system includes, in sequence from an object plane to an image plane along an optical axis: a first lens, a second lens, a third lens, and a fourth lens;

[0005] The object side of the first lens is convex, the image side is concave, and its optical power is negative;

[0006] The object side of the second lens is convex, the image side is concave, and its optical power is positive;

[0007] The object side of the third lens is concave, the image side is convex, and its optical power is positive;

[0008] The object side of the fourth lens is convex, and the image side is concave.

[0009] On the other hand, an embodiment of the present invention further provides a camera module.

[0010] A camera module comprises at least an optical lens, in which the above-mentioned high-pixel infrared optical system is installed.

[0011] The optical system and camera module of the embodiment of the present invention are mainly composed of 4 lenses, with a small number of lenses and a simple structure. Different lenses are combined with each other and the optical focal length is reasonably distributed, and good optical performance such as large aperture, small distortion, high pixel, and very good heat elimination is achieved. Description of the drawings:

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0013] Figure 1 The structure of the optical system or camera module of the present invention is shown in FIG. Figure 1 ;

[0014] Figure 2 A distortion curve diagram of the optical system or camera module of the present invention at +25°C;

[0015] Figure 3 It is an MTF curve diagram of the optical system or camera module of the present invention at +25°C;

[0016] Figure 4 A relative illumination diagram of the optical system or camera module of the present invention at +25°C;

[0017] Figure 5 It is an MTF curve diagram of the optical system or camera module of the present invention at -40°C;

[0018] Figure 6 It is an MTF curve diagram of the optical system or camera module of the present invention at +85°C;

[0019] Figure 7 The structure of the optical system or camera module of the present invention is shown in FIG. Figure 2 ; Specific implementation method:

[0020] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] When the embodiments of the present invention mention ordinal numbers such as "first" and "second", unless they do express the meaning of order according to the context, they should be understood as being merely for the purpose of distinction.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] An embodiment of the present invention provides a high-pixel infrared optical system, which includes, along the optical axis from the object plane to the image plane, a first lens 1, a second lens 2, a third lens 3, and a fourth lens 4.

[0024] The object side of the first lens 1 is convex, the image side is concave, and its optical power is negative;

[0025] The object side of the second lens 2 is convex, the image side is concave, and its optical power is positive;

[0026] The object side of the third lens 3 is concave, the image side is convex, and its optical power is positive;

[0027] The object side of the fourth lens 4 is convex, and the image side is concave, and its optical power can be positive or negative.

[0028] The optical system of the embodiment of the present invention is mainly composed of 4 lenses, with a small number of lenses and a simple structure. Different lenses are combined with each other and the optical focal length is reasonably distributed, so it has good performance such as large aperture, small distortion, high pixel, and very good heat elimination.

[0029] For example, as a specific implementation of this solution but not limiting, Figure 1 As shown, in this embodiment, the object side of the first lens 1 is convex, the image side is concave, and its optical power is negative; the object side of the second lens 2 is convex, the image side is concave, and its optical power is positive; the object side of the third lens 3 is concave, the image side is convex, and its optical power is positive; the object side of the fourth lens 4 is convex, the image side is concave, and its optical power is positive.

[0030] For example, as a specific implementation of this solution but not limiting, Figure 7 As shown, in this embodiment, the object side of the first lens 1 is convex, the image side is concave, and its optical power is negative; the object side of the second lens 2 is convex, the image side is concave, and its optical power is positive; the object side of the third lens 3 is concave, the image side is convex, and its optical power is positive; the object side of the fourth lens 4 is convex, the image side is concave, and its optical power is negative.

[0031] Further, as a preferred implementation of the present solution but not limiting, the optical system satisfies: TTL / EFL≤1.79, wherein TTL is the distance between the vertex on the object side of the first lens 1 of the optical system and the imaging plane 6, and EFL is the effective focal length of the optical system. By combining different lenses and reasonably allocating the optical power, the optical system has good performances such as large aperture, small distortion, high pixel, and very good athermalization.

[0032] Furthermore, as a preferred implementation of the present solution but not a limitation, the first lens and the second lens are glued together to form a combined lens. The structure is simple and compact, and good optical performance can be ensured by combining different lenses and reasonably allocating optical power.

[0033] Furthermore, as a preferred implementation of this solution but not limiting, each lens of the optical system satisfies the following conditions:

[0034] (1)-10 <f1<-3;

[0035] (2) 2 < f2 < 5;

[0036] (3) 3 < f3 < 10;

[0037] (4) -270 < f4 < 100;

[0038] Among them, f1 is the focal length of the first lens 1, f2 is the focal length of the second lens 2, f3 is the focal length of the third lens 3, and f4 is the focal length of the fourth lens 4. Through the mutual combination of different lenses and the reasonable distribution of the optical power, the optical system has good performances such as a large aperture, small distortion, high pixels, and very good thermal aberration correction.

[0039] Furthermore, as a preferred implementation manner of this solution rather than a limitation, each lens of the optical system satisfies the following conditions:

[0040] (1) -3.0 < f1 / f < -1.0;

[0041] (2) 0.5 < f2 / f < 3.0;

[0042] (3) 0.5 < f3 / f < 3.0;

[0043] (4) -50.0 < f4 / f < 20.0;

[0044] Among them, f is the focal length of the entire optical system, f1 is the focal length of the first lens 1, f2 is the focal length of the second lens 2, f3 is the focal length of the third lens 3, and f4 is the focal length of the fourth lens 4. Through the mutual combination of different lenses and the reasonable distribution of the optical power, the optical system has good performances such as a large aperture, small distortion, high pixels, and very good thermal aberration correction.

[0045] Still further, as a preferred implementation manner of this solution rather than a limitation, the refractive index Nd1 and Abbe number Vd1 of the material of the first lens 1 satisfy: 1.40 < Nd1 < 1.70, 50 < Vd1 < 90. The structure is simple, and good optical performance can be ensured.

[0046] Furthermore, as a preferred implementation manner of this solution rather than a limitation, the refractive index Nd2 and Abbe number Vd2 of the material of the second lens 2 satisfy: 1.85 < Nd2 < 2.05, 20 < Vd2 < 40. The structure is simple, and good optical performance can be ensured.

[0047] Still further, as a preferred implementation manner of this solution rather than a limitation, the refractive index Nd3 and Abbe number Vd3 of the material of the third lens 3 satisfy: 1.50 < Nd3 < 1.70, 20 < Vd3 < 40. The structure is simple, and good optical performance can be ensured.

[0048] Furthermore, as a preferred implementation rather than a limitation of this solution, the refractive index Nd4 and Abbe number Vd4 of the material of the fourth lens 4 satisfy: 1.50 < Nd4 < 1.70, 20 < Vd4 < 40. The structure is simple, which can ensure good optical performance.

[0049] Furthermore, as a specific implementation rather than a limitation of this solution, the aperture stop 5 of the optical system is located between the second lens 2 and the third lens 3. It is used to adjust the intensity of the light beam. Preferably, the aperture stop 5 is arranged on the object side of the second lens 2. In this embodiment, the positions of each lens and the aperture stop are fixed.

[0050] Furthermore, as a preferred implementation rather than a limitation of this solution, the third lens 3 and the fourth lens 4 are plastic aspherical lenses. It can effectively eliminate the influence of spherical aberration on the lens performance, improve the resolution of the optical lens, can effectively achieve thermal difference elimination, and at the same time reduce the processing difficulty and production cost of the lens.

[0051] Furthermore, as a preferred implementation rather than a limitation of this solution, a band-pass filter is provided between the fourth lens 4 and the image plane 6. It can filter the visible light in the environment to avoid the interference phenomenon of visible light.

[0052] Specifically, in combination with Figure 1 , in this embodiment, the focal length f1 of the first lens 1 = -7.938 mm, the focal length f2 of the second lens 2 = 3.562 mm, the focal length f3 of the third lens 3 = 8.168 mm, and the focal length f4 of the fourth lens 4 = 67.417 mm. In this embodiment, along the optical axis direction, the thickness value D1 from the vertex on the object side to the vertex on the image side of the first lens 1, the thickness value D2 from the vertex on the object side to the vertex on the image side of the second lens 2, and the interval D3 from the vertex on the image side of the second lens 2 to the vertex on the object side of the third lens 3 satisfy: D1 + D2 < D3. The basic parameters of this optical system are shown in the following table:

[0053] surface Curvature radius R(mm) Interval D(mm) Refractive index Nd Dispersion value Vd S1 12.0 0.50 1.5 70 S2 2.5 1.00 1.9 35 S3 17.0 0.15 STO INFINITY 1.80 S5 -2.0 1.30 1.6 23 S6 -1.5 0.10 S7 4.5 1.50 1.6 23 S8 4.0 2.00 S9 INFINITY 0.70 1.5 64 S10 INFINITY 0.30 IMA INFINITY 0.00

[0054] In the above table, along the optical axis from the object plane to the image plane, S1 and S2 correspond to the two surfaces of the first lens 1; S2 and S3 correspond to the two surfaces of the second lens 2; STO is the position of the aperture stop; S5 and S6 correspond to the two surfaces of the third lens 3; S7 and S8 correspond to the two surfaces of the fourth lens 4; S9 and S10 correspond to the two surfaces of the band-pass filter; IMA is the image plane 6.

[0055] More specifically, the surfaces of the third lens 3 and the fourth lens 4 are aspherical shapes, and they satisfy the following equations: Among them, parameter c=1 / R, that is, the curvature corresponding to the radius, y is the radial coordinate, and its unit is the same as the lens length unit, k is the conic quadratic coefficient, and a1 to a6 are the coefficients corresponding to each radial coordinate. The aspheric surface related values ​​of the S5 surface and the S6 surface of the third lens 3 and the S7 surface and the S8 surface of the fourth lens 4 are shown in the following table:

[0056] K <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4]]> S5 -0.40 0 -0.003409507633833000 -0.016038167970829999 0.012480154401390000 S6 -0.70 0 0.000235028520440300 -0.000038830217112540 0.000330841178015300 S7 0.20 0 -0.022305296602539999 0.005448659620065000 -0.000838933906264700 S8 0.80 0 -0.040782844476839997 0.006602358763897000 -0.000803390991681700

[0057] from Figures 2 to 6 It can be seen that the optical system in this embodiment has good optical performances such as high resolution and very good athermal performance.

[0058] A camera module comprises at least an optical lens, in which the above-mentioned high-pixel infrared optical system is installed.

[0059] The optical system and camera module of the embodiment of the present invention are mainly composed of 4 lenses, with a small number of lenses and a simple structure. Different lenses are combined with each other and the optical focal length is reasonably distributed, so they have good performance such as large aperture, small distortion, high pixel, and very good heat elimination.

[0060] As described above, one or more implementation methods are provided in combination with specific contents, and the specific implementation of the present invention is not limited to these descriptions. Any similarity or similarity with the method, structure, etc. of the present invention, or any technical deduction or replacement based on the concept of the present invention, shall be regarded as the protection scope of the present invention.

Claims

1. A high-pixel infrared optical system, comprising: The first lens, the second lens, the third lens, and the fourth lens are characterized in that: The object side of the first lens is convex, the image side is concave, and its optical power is negative; The object side of the second lens is convex, the image side is concave, and its optical power is positive; The object side of the third lens is concave, the image side is convex, and its optical power is positive; The object side of the fourth lens is convex, and the image side is concave; The material refractive index Nd3 and material Abbe constant Vd3 of the third lens meet the following requirements: 1.50 <Nd3<1.70, 20<Vd3<40; The material refractive index Nd4 and the material Abbe constant Vd4 of the fourth lens satisfy: 1.50 <Nd4<1.70, 20<Vd4<40; Each lens of the optical system meets the following conditions: （1）-10<f1<-3； （2）2<f2<5； （3）3<f3<10； （4）-270<f4<100； Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens; and / or Each lens of the optical system meets the following conditions: (1) -3.0 <f1 / f<-1.0; (2) 0.5 <f2 / f<3.0; (3) 0.5 <f3 / f<3.0; (4) -50.0 <f4 / f<20; Where f is the focal length of the entire optical system, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

2. The high-pixel infrared optical system according to claim 1, characterized in that: The optical system satisfies: TTL / EFL≤1.79, wherein TTL is the distance between the vertex on the object side of the first lens of the optical system and the imaging surface, and EFL is the effective focal length of the optical system.

3. The high-pixel infrared optical system according to claim 1, characterized in that: The first lens and the second lens are glued together to form a combined lens.

4. The high-pixel infrared optical system according to claim 1, characterized in that: The aperture of the optical system is located between the second lens and the third lens and close to one side of the second lens.

5. The high-pixel infrared optical system according to claim 1, 2, 3 or 4, characterized in that: The material refractive index Nd1 and material Abbe constant Vd1 of the first lens satisfy: 1.40 <Nd1<1.70, 50<Vd1<90。 6. The high-pixel infrared optical system according to claim 1, 2, 3 or 4, characterized in that: The material refractive index Nd2 and material Abbe constant Vd2 of the second lens meet the following requirements: 1.85 <Nd2<2.05, 20<Vd2<40。 7. A camera module, comprising at least an optical lens, characterized in that: The high-pixel infrared optical system according to any one of claims 1 to 6 is installed in the optical lens.

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