Small day and night dual-purpose optical lens and imaging method thereof

Abstract

The invention relates to a small day and night dual-purpose optical lens. An optical system of the lens is composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from left to right along a light incident light path. Under the condition that retroflexion caused by aspheric coefficients is not considered, the first lens is a negative meniscus lens, the second lens is a negative meniscus lens, the third lens is a positive meniscus lens, the fourth lens is a biconvex positive lens, the fifth lens is a biconcave negative lens, and the sixth lens is a biconvex positive lens. The third lens is a glass spherical lens, the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are plastic aspheric lenses, and the fourth lens and the fifth lens form a balsaming lens group. By reasonably distributing the focal power and the surface type of each lens, the central thickness of each lens, the axial distance between the lenses and the like, the imaging performance requirement of the lens is met, the total length of the lens and the radial size of each lens are reduced, and the miniaturization of the lens group is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a small day and night dual-purpose optical lens and an imaging method thereof, and relates to the technical field of lenses. BACKGROUND

[0002] With the rapid development of automotive intelligence and autonomous driving technology, the vehicle-mounted optical monitoring system (OMS) has become a key component for improving vehicle safety and user experience. The OMS lens is mainly used for real-time monitoring of the state of the vehicle occupants. In modern automobile design, the OMS lens needs to be integrated in the instrument panel, rearview mirror or sunroof, etc. to achieve wide field of view coverage of the front and rear passengers, while supporting infrared night vision and AI image recognition functions to adapt to diversified driving scenarios. However, the use environment of the OMS lens is extremely harsh. During vehicle driving, it will face challenges such as severe vibration, extreme temperature change, high humidity, dust pollution and strong light interference. These environmental factors require the lens to have high durability, stable optical performance and anti-interference ability. In addition, under the trend of electrification and intelligence, automobile manufacturers have higher requirements for the size, weight and power consumption of the OMS lens to optimize the layout of the vehicle space and energy efficiency. The OMS lens of the prior art mostly adopts all-glass lenses or complex multi-piece group structures, which, although performs well in optical quality, has problems such as high cost, large weight and volume, which is not conducive to cost control and lightweight design. SUMMARY

[0003] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a small day and night dual-purpose optical lens and an imaging method thereof. While achieving clear imaging, the lens has a small size and low manufacturing cost.

[0004] In order to solve the above technical problems, the technical scheme of the present application is as follows: a small day and night dual-purpose optical lens, the optical system of the lens is composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens arranged in order from left to right along the light incident path; without considering the reverse curvature caused by the aspherical surface coefficient, the first lens is a meniscus negative lens, the object side surface is convex, and the image side surface is concave; the second lens is a meniscus negative lens, the object side surface is concave, and the image side surface is convex; the third lens is a meniscus positive lens, the object side surface is concave, and the image side surface is convex; the fourth lens is a double-convex positive lens, the object side surface is convex, and the image side surface is convex; the fifth lens is a double-concave negative lens, the object side surface is concave, and the image side surface is concave; the sixth lens is a double-convex positive lens, the object side surface is convex, and the image side surface is convex; the third lens is a glass spherical lens, the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are plastic aspherical lenses, and the fourth lens and the fifth lens constitute a cemented lens group.

[0005] Preferably, the focal length of the optical system is set as f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f1, f2, f3, f4, f5 and f6 respectively, wherein f1, f2, f3, f4, f5 and f6 satisfy the following ratios: -3.0 < f1 / f < -2.0, -29.0 < f2 / f < -28.0, 2.0 < f3 / f < 3.0, 1.0 < f4 / f < 2.0, -2.0 < f5 / f < -1.0, and 2.0 < f6 / f < 3.0.

[0006] Preferably, the first lens satisfies the relationship: 1.3 ≤ Nd ≤ 1.6 and Vd ≥ 50; the second lens satisfies the relationship: 1.3 ≤ Nd ≤ 1.6 and Vd ≤ 50; the third lens satisfies the relationship: 1.7 ≤ Nd ≤ 2.0 and Vd ≤ 50; the fourth lens satisfies the relationship: 1.3 ≤ Nd ≤ 1.6 and Vd ≥ 50; the fifth lens satisfies the relationship: 1.3 ≤ Nd ≤ 1.6 and Vd ≤ 50; and the sixth lens satisfies the relationship: 1.3 ≤ Nd ≤ 1.6 and Vd ≥ 50; wherein Nd is the refractive index and Vd is the Abbe number.

[0007] Preferably, the on-axis distance between each lens satisfies the following relationships: the air gap between the first lens and the second lens is 2.0-2.5 mm; the air gap between the second lens and the third lens is 0.1-0.5 mm; the air gap between the third lens and the diaphragm is 0.0-0.5 mm; the air gap between the diaphragm and the fourth lens is 0.5-1.0 mm; the fourth lens and the fifth lens are cemented lens groups, and the air gap is 0; and the air gap between the fifth lens and the sixth lens is 0.1-0.5 mm.

[0008] Preferably, the aspheric surface curve equation of the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens is:

[0009]

[0010] wherein z is the sagittal height of the aspheric surface at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, r = 1 / c; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7 and α8 are high-order coefficients.

[0011] Preferably, the total optical length TTL of the optical system and the focal length f of the optical system satisfy the relationship: TTL / f ≤ 8.7.

[0012] Preferably, the F number of the optical system is ≤ 2.1.

[0013] Preferably, the image height H of the optical system and the focal length f of the optical system satisfy the relationship: H / f ≥ 1.6.

[0014] Preferably, a filter is provided on the rear side of the sixth lens.

[0015] An imaging method for a small day and night dual-use optical lens is performed according to the following steps: light rays pass through a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens in sequence to form an image.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention provides a small day / night dual-use optical lens using six optical lenses, consisting of one glass spherical lens and five plastic aspherical lenses to form an imaging system. The use of plastic aspherical lenses, which are far less expensive than glass lenses, reduces production costs while ensuring image quality. The total length of the lens is less than 15 mm, and the outer diameter is less than 10 mm, ensuring the optical performance of the camera assembly while reducing the overall size of the lens and improving aesthetics. Furthermore, the inclusion of a glass spherical lens in the second to fourth lenses further enhances the overall image quality, controls temperature drift, and strengthens the stability of the image quality under high and low temperature conditions.

[0018] 2. The lens has an imaging angle of more than 160 degrees and features high imaging clarity, large aperture, low tolerance sensitivity and good high and low temperature stability, enabling more comprehensive monitoring of the in-vehicle scene.

[0019] 3. By rationally matching the various optical lenses, the system structure is compact and reasonable, easy to assemble, has low tolerance sensitivity, and is more suitable for large-scale high-yield production;

[0020] 4. Using one glass lens in combination with five plastic lenses reduces costs while adapting to different environments;

[0021] 5. It can effectively compensate for focal plane displacement at high and low temperatures, and has adaptability to complex environments;

[0022] 6. The chromatic aberration along each axis, the transverse chromatic aberration, and higher-order chromatic aberrations have been corrected to ensure that the imaging system can maintain high imaging quality even at large angles.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0024] Fig. 1 This is a schematic diagram of the optical structure of the present invention;

[0025] Fig. 2 This is the axial chromatic aberration diagram of the entire working band of the present invention;

[0026] Fig. 3This is the transverse chromatic aberration diagram of the entire working band of the present invention;

[0027] Fig. 4 This is the field curvature distortion diagram of the entire working band of the present invention;

[0028] In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; IR - filter; CG - sensor protective glass; IMA - imaging plane. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] like Figs. 1-4 As shown, this embodiment provides a small day / night dual-use optical lens. The optical system of the lens consists of a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens arranged sequentially from left to right along the incident light path. Without considering the curvature caused by the aspherical coefficient, the first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; the third lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface; the fourth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fifth lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; and the sixth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface. The third lens is a glass spherical lens, while the first, second, fourth, fifth, and sixth lenses are plastic aspherical lenses. The fourth and fifth lenses form a cemented lens group.

[0033] The first, second, and fifth lenses are all aspherical lenses with negative optical power, which reduce optical system distortion while adjusting large-angle light. The fourth and fifth lenses form an achromatic cemented doublet. This reasonable lens combination enables the optical system to achieve a small size, ultra-wide angle, large aperture, day and night confocal focus, and low temperature drift design. It also provides good correction for on-axis and off-axis aberrations, resulting in good image quality. Figs. 2 to 4 As shown.

[0034] In this embodiment of the invention, the focal length of the optical system is set to f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are f1, f2, f3, f4, f5, and f6, respectively, wherein f1, f2, f3, f4, f5, and f6 satisfy the following ratio with f: -3.0 <f1 / f<-2.0,-29.0<f2 / f<-28.0,2.0<f3 / f<3.0,1.0<f4 / f<2.0,-2.0<f5 / f<-1.0,2.0<f6 / f<3.0。

[0035] In this embodiment of the invention, the first lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the second lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≤50; the third lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; the fourth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the fifth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≤50; and the sixth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; where Nd is the refractive index and Vd is the Abbe constant.

[0036] In this embodiment of the invention, the on-axis distances between the lenses satisfy the following relationships: the air gap between the first lens and the second lens is 2.0 to 2.5 mm; the air gap between the second lens and the third lens is 0.1 to 0.5 mm; the air gap between the third lens and the aperture stop is 0.0 to 0.5 mm; the air gap between the aperture stop and the fourth lens is 0.5 to 1.0 mm; the fourth lens and the fifth lens are a cemented lens group with an air gap of 0; and the air gap between the fifth lens and the sixth lens is 0.1 to 0.5 mm.

[0037] In this embodiment of the invention, the equations for the aspherical curves of the first, second, fourth, fifth, and sixth lenses are as follows:

[0038]

[0039] Where z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface, r = 1 / c; k is the conic constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

[0040] In this embodiment of the invention, the total optical length TTL of the optical system and the focal length f of the optical system satisfy the following condition: TTL / f≤8.7.

[0041] In this embodiment of the invention, the F-number of the optical system is ≤2.1.

[0042] In this embodiment of the invention, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥1.6.

[0043] In this embodiment of the invention, a filter is provided on the rear side of the sixth lens.

[0044] In this embodiment of the invention, the technical specifications achieved by the optical system are as follows:

[0045] (1) Focal length: 1.3≤EFFL≤1.7mm;

[0046] (2) Aperture F≤2.1;

[0047] (3) Field of view: 2w ≥ 160°;

[0048] (4) Operating bands: visible light band and short-wave infrared band.

[0049] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0050]

[0051] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0052]

[0053] An imaging method for a small day and night dual-use optical lens is performed according to the following steps: light rays pass through a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens in sequence to form an image.

[0054] The optical system in this embodiment achieves miniaturization of the lens assembly and reduces costs by rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis distance between each lens, while meeting the lens imaging performance requirements.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A small day / night dual-use optical lens, characterized in that: The optical system of the lens consists of a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens arranged sequentially from left to right along the incident light path. Without considering the curvature caused by aspherical coefficients, the first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; the third lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface; the fourth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fifth lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; and the sixth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface. The third lens is a glass spherical lens, while the first, second, fourth, fifth, and sixth lenses are plastic aspherical lenses. The fourth and fifth lenses form a cemented lens group.

2. The compact day / night dual-use optical lens according to claim 1, characterized in that: Let the focal length of the optical system be f. The focal lengths of the first, second, third, fourth, fifth, and sixth lenses are f1, f2, f3, f4, f5, and f6, respectively. The ratios of f1, f2, f3, f4, f5, and f6 to f satisfy the following condition: -3.0 <f1 / f<-2.0,-29.0<f2 / f<-28.0,2.0<f3 / f<3.0,1.0<f4 / f<2.0,-2.0<f5 / f<-1.0,2.0<f6 / f<3.0。 3. The compact day / night dual-use optical lens according to claim 1, characterized in that: The first lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the second lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≤50; the third lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; the fourth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the fifth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≤50; the sixth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; where Nd is the refractive index and Vd is the Abbe constant.

4. The compact day / night dual-use optical lens according to claim 1, characterized in that: The on-axis distances between the lenses satisfy the following relationships: the air gap between the first lens and the second lens is 2.0~2.5mm; the air gap between the second lens and the third lens is 0.1~0.5mm; the air gap between the third lens and the aperture stop is 0.0~0.5mm; the air gap between the aperture stop and the fourth lens is 0.5~1.0mm; the fourth lens and the fifth lens are a cemented lens group with an air gap of 0; and the air gap between the fifth lens and the sixth lens is 0.1~0.5mm.

5. The compact day / night dual-use optical lens according to claim 1, characterized in that: The equations for the aspherical curves of the first, second, fourth, fifth, and sixth lenses are as follows: Where z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface, r = 1 / c; and k is the conic constant. All are coefficients of higher-order terms.

6. The compact day / night dual-use optical lens according to claim 1, characterized in that: The total optical length (TTL) of an optical system and the focal length (f) of the optical system satisfy the following condition: TTL / f ≤ 8.

7.

7. The compact day / night dual-use optical lens according to claim 1, characterized in that: The F-number of the optical system is ≤2.

1.

8. The compact day / night dual-use optical lens according to claim 1, characterized in that: The image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥1.

6.

9. The compact day / night dual-use optical lens according to claim 1, characterized in that: A filter is provided on the rear side of the sixth lens.

10. An imaging method for a small day / night dual-use optical lens as described in any one of claims 1-9, characterized in that, The following steps are performed: light rays pass through the first lens, the second lens, the third lens, the aperture stop, the fourth lens, the fifth lens, and the sixth lens in sequence to form an image.

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