Small-caliber optical lens

Abstract

The utility model relates to a small-caliber optical lens, and aims to realize the design targets of high imaging quality, ultra-wide field of view and miniaturization by optimizing parameters such as focal power, curved surface shape, thickness and the like of a lens. The lens is composed of four plastic lenses which are a first lens (P1) with negative focal power, a second lens (P2) with positive focal power, a third lens (P3) with positive focal power and a fourth lens (P4) with positive focal power in sequence from an object side to an imaging surface along an optical axis. The design meets various optical parameter conditions, for example, the focal length ratio (-2 < f1 / f2 <-0.5, 0.2 < f3 / f4 < 1.2), the relation between the effective focal length and the focal length of each lens (for example,-3.004 < f1 / f <-2.554) and the like. In addition, the four lenses are all XY polynomial curved surfaces, and the mechanical structure and the optical performance are optimized. The lens adopts the design of four plastic lenses, is compact in structure, is suitable for miniaturized equipment, can capture more light rays, is suitable for low-light conditions, and can be used for mobile phone cameras, security monitoring equipment and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical lenses, in particular to a small-aperture optical lens. BACKGROUND

[0002] With the continuous development of optical imaging technology, small-aperture optical lenses are increasingly widely used in various devices, such as mobile phone cameras, security monitoring devices, etc. However, the existing small-aperture optical lenses still have some deficiencies in imaging quality, optical power distribution, field of view, etc., and cannot meet the growing demand for high resolution, large field of view, etc. Therefore, a new type of small-aperture optical lens is needed to improve the imaging quality and optical performance. SUMMARY

[0003] The present application aims to provide a small-aperture optical lens that achieves good imaging effect and optical performance by reasonably designing the optical power, curved surface shape, thickness, etc. of the lenses.

[0004] The present application adopts the following technical solutions:

[0005] A small-aperture optical lens composed of four plastic lenses, characterized in that, along the optical axis from the object side to the imaging surface, it includes:

[0006] a first lens (P1) with negative optical power, whose object side is convex and image side is concave;

[0007] a second lens (P2) with positive optical power, whose object side is concave and image side is convex;

[0008] a third lens (P3) with positive optical power, whose object side is convex and image side is concave;

[0009] a fourth lens (P4) with positive optical power, whose object side is convex and image side is concave;

[0010] wherein the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: -2 < f1 / f2 < -0.5; the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 0.2 < f3 / f4 < 1.2.

[0011] Further, the four lenses of the small-aperture optical lens are all XY polynomial curved surfaces.

[0012] Further, the effective focal length f of the small-aperture optical lens and the focal length f1 of the first lens satisfy: -3.004 < f1 / f < -2.554.

[0013] Further, the effective focal length f of the small-aperture optical lens and the focal length f2 of the second lens satisfy: 1.587 < f2 / f < 2.3.

[0014] Further, the effective focal length f of the small-aperture optical lens and the focal length f3 of the third lens satisfy: 3.031 < f3 / f < 3.435.

[0015] Further, the effective focal length f of the small-aperture optical lens and the focal length f4 of the fourth lens satisfy: 4.068 < f4 / f < 4.360.

[0016] Further, the image-side F number of the small-aperture optical lens satisfies: 2.3 < F < 2.7.

[0017] Further, the angle CA between the chief ray of the maximum field of view and the optical axis of the small-aperture optical lens satisfies: CA < 36°.

[0018] Further, the thickness CT1 of the first lens on the optical axis and the thickness CT2 of the second lens on the optical axis of the small-aperture optical lens satisfy: CT1 / CT2 < 1.06.

[0019] Further, the effective focal length f of the small-aperture optical lens and the distance TTL from the object-side surface of the first lens of the small-aperture optical lens to the imaging surface on the optical axis satisfy: 0.15 < f / TTL < 0.21.

[0020] Further, the maximum horizontal field of view angle HFOV of the small-aperture optical lens satisfies: HFOV > 120°.

[0021] Further, the ratio of the maximum horizontal field of view angle HFOV to the maximum vertical field of view angle VFOV of the small-aperture optical lens satisfies: HFOV / VFOV > 3.7.

[0022] The small-aperture optical lens of the present application achieves the design goals of high imaging quality, ultra-wide field of view, and miniaturization by optimizing the refractive power, shape, and arrangement order of the lenses. Compared with the prior art, the present application has the following advantages:

[0023] 1. Four plastic lenses are used in the design, and the structure is compact, suitable for miniaturized equipment.

[0024] 2. By optimizing the focal length ratio and optical parameters, an ultra-wide field of view is achieved.

[0025] 3. The image-side F number is small, which can capture more light, suitable for low light conditions.

[0026] 4. Optimized field of view angle and distortion control ensure imaging quality. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1A structure diagram of a first embodiment of the present application;

[0028] Figure 2 A distortion diagram of the first embodiment of the present application;

[0029] Figure 3 An astigmatism curve diagram of the first embodiment of the present application; DETAILED DESCRIPTION

[0030] For a better understanding of the present application, various aspects of the present application will be described in greater detail below with reference to the accompanying drawings. It is to be noted that these detailed descriptions are merely descriptive of embodiments of the present application and are not intended in any way to limit the scope of the present application. Throughout the specification, like drawing reference numerals refer to like elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] It should be noted that the expressions first, second, third, and the like, in this specification are merely used to distinguish one feature from another feature, and do not represent any limitation on the features. Thus, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0032] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shape of the spherical surface or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or aspherical surface is not limited to the shape of the spherical surface or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0033] In this specification, the paraxial region refers to a region near the optical axis. If a lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is referred to as the object side surface of the lens, and the surface of each lens closest to the image plane is referred to as the image side surface of the lens.

[0034] It should also be understood that the words "comprise", "comprising", "include", "including", and / or "contain", when used in this specification, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. In addition, when the expression such as "at least one of" appears after a list of items, it modifies the entire list of items and does not modify the individual items in the list. Furthermore, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the expression "exemplary" is intended to mean an example or an illustration.

[0035] Unless otherwise defined, all terms (including 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 belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an overly idealized or overly formal sense unless expressly so defined herein.

[0036] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0037] The optical lens provided by the example of the present application is a small-aperture optical lens composed of four plastic lenses, characterized in that, along the optical axis from the object side to the imaging surface, there are sequentially included:

[0038] a first lens (P1) with negative optical power, the object side surface of which is a convex surface, and the image side surface of which is a concave surface;

[0039] a second lens (P2) with positive optical power, the object side surface of which is a concave surface, and the image side surface of which is a convex surface;

[0040] a third lens (P3) with positive optical power, the object side surface of which is a convex surface, and the image side surface of which is a concave surface;

[0041] a fourth lens (P4) with positive optical power, the object side surface of which is a convex surface, and the image side surface of which is a concave surface;

[0042] wherein the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: -2 < f1 / f2 < -0.5; and the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 0.2 < f3 / f4 < 1.2.

[0043] In some embodiments, the four lenses of the small-aperture optical lens are all XY polynomial curved surfaces, which satisfy the above conditions, can effectively optimize the optical performance, and reduce aberration.

[0044] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f1 of the first lens satisfy: -3.004 < f1 / f < -2.554, which satisfies the above condition, so that more incident light rays enter the system, and the imaging quality is improved.

[0045] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f2 of the second lens satisfy: 1.587 < f2 / f < 2.3, which satisfies the above condition, and is conducive to reducing the difficulty of distortion correction.

[0046] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f3 of the third lens satisfy: 3.031 < f3 / f < 3.435, which satisfies the above condition, and is beneficial to increase the light divergence degree and improve the lens imaging quality.

[0047] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f4 of the fourth lens satisfy: 4.068 < f4 / f < 4.360, which satisfies the above condition, and can effectively reduce the correction difficulty of field curvature and distortion and improve the overall resolution.

[0048] In some embodiments, the image-side F number of the small-aperture optical lens satisfies: 2.3 < F < 2.7, which satisfies the above condition, and can capture more light, making it suitable for low-light conditions.

[0049] In some embodiments, the angle CA between the maximum field of view chief ray of the small-aperture optical lens and the optical axis satisfies: CA < 36°, which satisfies the above condition, and can optimize the optical design and reduce distortion.

[0050] In some embodiments, the thickness CT1 of the first lens on the optical axis of the small-aperture optical lens and the thickness CT2 of the second lens on the optical axis satisfy: CT1 / CT2 < 1.06, which satisfies the above condition, and can optimize the mechanical structure and optical performance.

[0051] In some embodiments, the effective focal length f of the small-aperture optical lens and the distance TTL from the first lens material side to the imaging surface on the optical axis of the small-aperture optical lens satisfy: 0.15 < f / TTL < 0.21, which satisfies the above condition, and can effectively limit the lens length, which is beneficial to realize the miniaturization of the optical lens.

[0052] In some embodiments, the maximum transverse field of view angle HFOV of the small-aperture optical lens satisfies: HFOV > 120°, which satisfies the above condition, and can realize a super-wide-angle field of view.

[0053] In some embodiments, the ratio of the maximum transverse field of view angle HFOV to the maximum longitudinal field of view angle VFOV of the small-aperture optical lens satisfies: HFOV / VFOV > 3.7, which satisfies the above condition, and can further optimize the optical design and improve the imaging quality.

[0054] Embodiment 1

[0055] As a specific embodiment of the present application, the parameters of a small-aperture optical lens are shown in Table 1 below:

[0056] Table 1 Structure parameter table of a small-aperture optical lens

[0057]

[0058]

[0059] Table 2 Lens surface coefficients for a small aperture optical lens

[0060]

[0061]

[0062]

[0063] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0064] Those skilled in the art easily understand that the above are only the preferred embodiments of the present application, and are not intended to limit the present application. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A small-diameter optical lens, composed of four plastic lenses, characterized in that, Along the optical axis from the object side to the imaging plane, the following are included in sequence: The first lens (P1) with negative optical power has a convex object side and a concave image side. The second lens (P2) has positive optical power, with a concave object side and a convex image side. The third lens (P3) with positive optical power has a convex object side and a concave image side. The fourth lens (P4) has positive optical power, with a convex object side and a concave image side. Wherein, the focal lengths f1 and f2 of the first lens satisfy: -2 < f1 / f2 < -0.5; the focal lengths f3 and f4 of the third lens satisfy: 0.2 < f3 / f4 < 1.

2.

2. A small-aperture optical lens according to claim 1, characterized in that, The four lenses of the small-aperture optical lens are all XY polynomial surfaces.

3. A small-aperture optical lens according to claim 1, characterized in that, The effective focal length f of the small-aperture optical lens and the focal length f1 of the first lens satisfy: -3.004 <f1 / f<-2.554。 4. A small-aperture optical lens according to claim 1, characterized in that, The effective focal length f of the small-aperture optical lens and the focal length f2 of the second lens satisfy: 1.587 <f2 / f<2.3。 5. A small-aperture optical lens according to claim 1, characterized in that, The effective focal length f of the small-aperture optical lens and the focal length f3 of the third lens satisfy: 3.031 <f3 / f<3.435。 6. A small-aperture optical lens according to claim 1, characterized in that, The effective focal length f of the small-aperture optical lens and the focal length f4 of the fourth lens satisfy: 4.068 <f4 / f<4.360。 7. A small-aperture optical lens according to claim 1, characterized in that, The image-square F-number of the small-aperture optical lens satisfies: 2.3 < F < 2.

7.

8. A small-aperture optical lens according to claim 1, characterized in that, The angle CA between the principal ray of the maximum field of view and the optical axis of the small-aperture optical lens satisfies: CA < 36°.

9. A small-aperture optical lens according to claim 1, characterized in that, The thickness CT1 of the first lens on the optical axis and the thickness CT2 of the second lens on the optical axis of the small-aperture optical lens satisfy: CT1 / CT2 < 1.

06.

10. A small-aperture optical lens according to claim 1, characterized in that, The effective focal length f of the small-aperture optical lens and the distance TTL from the object side of the first lens to the imaging plane on the optical axis satisfy: 0.15 < f / TTL < 0.

21.

11. A small-aperture optical lens according to claim 1, characterized in that, The maximum lateral field of view (HFOV) of the small-aperture optical lens satisfies: HFOV > 120°.

12. A small-aperture optical lens according to claim 1, characterized in that, The ratio of the maximum lateral field of view (HFOV) to the maximum longitudinal field of view (VFOV) of the small-aperture optical lens satisfies the condition that HFOV / VFOV > 3.7.

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