A low-distortion 4K pixel optical lens and imaging method thereof

Abstract

The present invention relates to a low-distortion 4K pixel optical lens and an imaging method thereof, wherein the optical system comprises a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged from left to right along the incident light path of the light; the first lens L1 is a meniscus positive lens, the second lens L2 is a double convex positive lens, the third lens L3 is a double concave negative lens, the fourth lens L4 is a double concave negative lens, the fifth lens L5 is a double convex positive lens, the sixth lens L6 is a double convex positive lens, and the seventh lens L7 is a meniscus negative lens. The above lenses are all spherical lenses, and are all made of glass. The optical lens not only has stable imaging, but also has small distortion.

Description

Technical Field

[0001] The present invention relates to the field of optical lens imaging, and in particular to a low-distortion 4K pixel optical lens and an imaging method thereof. Background Art

[0002] In the past two years, the country has issued many industry standards and policies to encourage ADAS products, and has made clear requirements for some large freight vehicles and special industry vehicles. The industry standards clearly stipulate that this type of product contains two main functions, one of which is forward collision warning.

[0003] The working environment of the vehicle-mounted lens is complex, and the imaging quality needs to be guaranteed within the range of -40℃ to 85℃. At the same time, small distortion is required to reduce the deformation of the imaging.

[0004] Therefore, the current market demand is for an optical lens with excellent temperature stability and high-quality imaging. Summary of the invention

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a low-distortion 4K pixel optical lens and an imaging method thereof, which not only has stable imaging but also has small distortion.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a low-distortion 4K pixel optical lens, whose optical system includes a first lens L1, a second lens L2, a third lens L3, an aperture, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7, which are arranged in sequence from left to right along the incident light path of the light. The first lens L1 is a meniscus positive lens, the second lens L2 is a double convex positive lens, the third lens L3 is a double concave negative lens, the fourth lens L4 is a double concave negative lens, the fifth lens L5 is a double convex positive lens, the sixth lens L6 is a double convex positive lens, and the seventh lens L7 is a meniscus negative lens. All of the above lenses are spherical lenses, and are made of glass.

[0007] Furthermore, the second lens and the third lens are glued together to form a glued lens, and the fourth lens and the fifth lens are glued together to form a glued lens.

[0008] Furthermore, the air gap between the first lens L1 and the second lens L2 is 0.1-1.6 mm, the air gap between the third lens L3 and the fourth lens L4 is 1.3-2.4 mm, the air gap between the fifth lens L5 and the sixth lens L6 is 0.1-0.3 mm, and the air gap between the sixth lens L6 and the seventh lens L7 is 3.9-4.8 mm.

[0009] Furthermore, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7, respectively, wherein f1, f2, f3, f4, f5, f6, and f7 satisfy the following ratio with f: 1.55 <f1 / f<1.68,0.51<f2 / f<0.81,-0.52<f3 / f<-0.45,-0.41<f4 / f<-0.37,0.35<f5 / f<0.42, 0.62<f6 / f<0.78,-1.2<f7 / f<-0.77。

[0010] Furthermore, the first lens satisfies the relationship: N d ≥1.8, V d ≤40; the second lens satisfies the relationship: N d ≥1.5, V d ≥60; the third lens satisfies the relationship: N d ≥1.6, V d ≤ 40; the fourth lens satisfies the relationship: N d ≥1.5, V d ≥40; the fifth lens satisfies the relationship: N d ≥1.7, V d ≤50; the sixth lens satisfies the relationship: N d ≥1.7, V d ≤50; the seventh lens satisfies the relationship: N d ≥1.7, V d ≤30; where N d is the refractive index, V d is the Abbe constant.

[0011] Furthermore, the total optical length TTL of the optical system and the focal length F of the optical system satisfy: TTL / F≤16.

[0012] An imaging method of a low-distortion 4K pixel optical lens is performed according to the following steps: light is imaged after passing through a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and a protective glass from left to right.

[0013] Compared with the prior art, the present invention has the following beneficial effects: the low-distortion 4K pixel optical lens not only has stable imaging but also has small distortion, which can effectively avoid imaging deformation.

[0014] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the optical structure of an embodiment of the present invention;

[0016] Figure 2 is a visible light MTF curve diagram of an embodiment of the present invention;

[0017] Figure 3 is an axial chromatic aberration curve diagram of an embodiment of the present invention;

[0018] Figure 4 2 is a lateral aberration diagram of an embodiment of the present invention.

[0019] In the figure: L1-first lens; L2-second lens; L3-third lens; STO-aperture; L4-fourth lens; L5-fifth lens; L6-sixth lens; L7-seventh lens; GC-protective glass; IMG-imaging surface. DETAILED DESCRIPTION

[0020] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description.

[0021] like Figures 1 to 4 As shown, a low-distortion 4K pixel optical lens, the optical system includes a first lens L1, a second lens L2, a third lens L3, an aperture STO, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7, which are arranged in sequence from left to right along the incident light path of the light. The first lens L1, the second lens L2, the third lens L3, the aperture, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7. The first lens L1 is a meniscus positive lens, the second lens L2 is a biconvex positive lens, the third lens L3 is a biconcave negative lens, the fourth lens L4 is a biconcave negative lens, the fifth lens L5 is a biconvex positive lens, the sixth lens L6 is a biconvex positive lens, and the seventh lens L7 is a meniscus negative lens. When imaging: the light passes through the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the filter and the protective glass from left to right to form an image.

[0022] In the embodiment of the present invention, the first lens L1 is a positive meniscus lens, whose object-side surface is convex and whose image-side surface is concave.

[0023] In the embodiment of the present invention, the second lens L2 is a biconvex positive lens, and both the object-side surface and the image-side surface thereof are convex.

[0024] In the embodiment of the present invention, the third lens L3 is a double concave negative lens, and both the object-side surface and the image-side surface thereof are concave.

[0025] In this embodiment of the present invention, the fourth lens L4 is a double concave negative lens, and both the object-side surface and the image-side surface thereof are concave surfaces.

[0026] In the embodiment of the present invention, the fifth lens L5 is a biconvex positive lens, and both the object-side surface and the image-side surface thereof are convex.

[0027] In the embodiment of the present invention, the sixth lens L6 is a biconvex positive lens, and both the object-side surface and the image-side surface thereof are convex.

[0028] In the embodiment of the present invention, the seventh lens L7 is a negative meniscus lens, whose object-side surface is concave and whose image-side surface is convex.

[0029] In the embodiment of the present invention, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are all spherical lenses, and are all made of glass.

[0030] In the embodiment of the present invention, the second lens and the third lens are glued together to form a glued lens, and the fourth lens and the fifth lens are glued together to form a glued lens.

[0031] In the embodiment of the present invention, the air interval between the first lens L1 and the second lens L2 is 0.1-1.6 mm, the air interval between the third lens L3 and the fourth lens L4 is 1.3-2.4 mm, the air interval between the fifth lens L5 and the sixth lens L6 is 0.1-0.3 mm, and the air interval between the sixth lens L6 and the seventh lens L7 is 3.9-4.8 mm.

[0032] In an embodiment of the present invention, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7, respectively, wherein f1, f2, f3, f4, f5, f6, and f7 satisfy the following ratio with f: 1.55 <f1 / f<1.68,0.51<f2 / f<0.81,-0.52<f3 / f<-0.45,-0.41<f4 / f<-0.37,0.35<f5 / f<0.42,0.62<f6 / f<0.78,-1.2<f7 / f<-0.77。

[0033] In an embodiment of the present invention, the first lens satisfies the relationship: N d ≥1.8, V d ≤40; the second lens satisfies the relationship: N d ≥1.5, V d ≥60; the third lens satisfies the relationship: N d ≥1.6, V d ≤40; the fourth lens satisfies the relationship: N d ≥1.5, V d≥40; the fifth lens satisfies the relationship: N d ≥1.7, V d ≤50; the sixth lens satisfies the relationship: N d ≥1.7, V d ≤50 where N d is the refractive index, V d is the Abbe constant.

[0034] In this embodiment of the present invention, a protective glass GC is disposed on the image side of the seventh lens L7.

[0035] In the embodiment of the present invention, the total optical length TTL of the optical system and the focal length F of the optical system satisfy: TTL / F≤16.

[0036] A working method of a low-distortion 4K pixel optical lens is performed in the following steps: during imaging: light rays pass through a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and a protective glass from left to right to form an image.

[0037] Table 1 shows the curvature radius R, thickness d, and refractive index N of each lens of the optical system of Example 1. d and the Abbe number V d .

[0038]

[0039]

[0040] Table 1 Specific lens parameters

[0041] In the embodiment of the present invention, the technical indicators achieved by this optical system are as follows:

[0042] (1) Focal length: EFFL = 15.4 mm; (2) Aperture F = 1.7; (3) Field of view: 2w ≥ 79°; (4) |Optical distortion|: < 3%; (5) Imaging circle diameter greater than φ9.8; (6) Working band: 420-680 nm; (7) Total optical length TTL ≤ 27 mm, optical back focus BFL ≥ 2 mm; (8) This lens is suitable for 4K pixel CCD or CMOS cameras.

[0043] Depend on Figure 2 It can be seen that the optical system has good MTF performance in the near-infrared band. The MTF value of the edge field of view is greater than 0.5 at the spatial frequency of 120pl / mm, and the MTF value of the center field of view is greater than 0.6 at the spatial frequency of 120pl / mm, which can meet the 4K resolution requirements. Figure 3 and Figure 4 is the axial chromatic aberration curve and lateral aberration of the optical system. Figure 3 It can be seen that the optical system has initially corrected the chromatic aberration, making the chromatic aberration at the aperture of 0.8 equal to 0, thus achieving the purpose of improving the image quality. Figure 4 It can be seen that the lateral aberration is within the Airy disk. In summary, it can be seen that the optical system has excellent imaging quality and fully meets the requirements of 4K pixel photography.

[0044] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of low-distortion 4K pixel optical lenses and imaging methods thereof under the inspiration of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A low-distortion 4K pixel optical lens, characterized by: The optical system comprises a first lens L1, a second lens L2, a third lens L3, an aperture, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7 which are arranged in sequence from left to right along the incident light path of the light; the first lens L1 is a meniscus positive lens, the second lens L2 is a biconvex positive lens, the third lens L3 is a biconcave negative lens, the fourth lens L4 is a biconcave negative lens, the fifth lens L5 is a biconvex positive lens, the sixth lens L6 is a biconvex positive lens, and the seventh lens L7 is a meniscus negative lens; all of the above lenses are spherical lenses and are made of glass; The focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7, respectively, wherein f1, f2, f3, f4, f5, f6, and f7 satisfy the following ratio with f: 1.55 <f1 / f<1.68,0.51<f2 / f<0.81,-0.52<f3 / f<-0.45,-0.41<f4 / f<-0.37,0.35<f5 / f<0.42,0.62<f6 / f<0.78,-1.2<f7 / f<-0.77; The second lens and the third lens are glued together to form a glued lens, and the fourth lens and the fifth lens are glued together to form a glued lens.

2. The low-distortion 4K pixel optical lens according to claim 1, characterized in that: The air gap between the first lens L1 and the second lens L2 is 0.1-1.6 mm, the air gap between the third lens L3 and the fourth lens L4 is 1.3-2.4 mm, the air gap between the fifth lens L5 and the sixth lens L6 is 0.1-0.3 mm, and the air gap between the sixth lens L6 and the seventh lens L7 is 0.5 mm.

3. The low-distortion 4K pixel optical lens according to claim 1, characterized in that: The first lens satisfies the relationship: N d ≥1.8, V d ≤40; the second lens satisfies the relationship: N d ≥1.5, V d ≥60; the third lens satisfies the relationship: N d ≥1.6, V d ≤40; the fourth lens satisfies the relationship: N d ≥1.5, V d ≥40; the fifth lens satisfies the relationship: N d ≥1.7, V d ≤50; the sixth lens satisfies the relationship: N d ≥1.7, V d ≤50; the seventh lens satisfies the relationship: N d ≥1.7, V d ≤30; where N d is the refractive index, V d is the Abbe constant.

4. The low-distortion 4K pixel optical lens according to claim 1, characterized in that: The total optical length TTL of the optical system and the focal length F of the optical system satisfy the following condition: TTL / F≤16.

5. An imaging method of a low-distortion 4K pixel optical lens, characterized in that: The low-distortion 4K pixel optical lens as described in any one of claims 1 to 4 is used, and the following steps are performed: light is imaged from left to right after passing through a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and a protective glass.

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