A five-element large-aperture optical system

Abstract

The present invention provides a five-element large-aperture optical system, which sequentially includes, from the object side to the image side along the optical axis: a diaphragm; a first lens with a positive focal power, whose object side is convex and whose image side is planar or concave; a second lens with a negative focal power, whose object side is concave and whose image side is convex or concave; a third lens with a positive focal power, whose object side is convex or planar and whose image side is convex; a fourth lens with a positive focal power, whose object side is convex and whose image side is planar or concave; a fifth lens with a negative focal power, whose object side is concave and whose image side is convex; the total length of the optical system satisfies the relation: 6.6 mm < TTL < 7.2 mm, and the f-number of the optical system satisfies the relation: 1.4 < FNO < 1.7, where TTL is the total length of the optical system and FNO is the f-number of the optical system, so that the five-element large-aperture optical system becomes a miniature system with a small volume and a light weight.

Description

Technical Field

[0001] The present invention relates to the technical field of optics, and particularly to a five-element large-aperture optical system. Background Art

[0002] With the rapid development of technology, the application scenarios of projection lenses have become increasingly diversified, which puts higher requirements on the performance and imaging quality of lenses in different environments. As the core optical component of AR glasses, the imaging quality, weight, size and other indicators of the display eyepiece directly affect the wearing experience and comfort. In recent years, people's requirements for portable optical engine systems in terms of volume, weight and image quality have been continuously increasing.

[0003] However, the optical engines of current products such as augmented reality glasses on the market generally have problems of large volume and high weight, and it is difficult to meet the development trend of lightweight and miniaturization of smart glasses. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a five-element large-aperture optical system to solve the problems in the above background art.

[0005] The invention provides the following technical solutions. A five-element large-aperture optical system includes, in order from the object side to the image side along the optical axis:

[0006] A diaphragm;

[0007] A first lens, having a positive focal power, with a convex object side and a flat or concave image side;

[0008] A second lens, having a negative focal power, with a concave object side and a convex or concave image side;

[0009] A third lens, having a positive focal power, with a convex or flat object side and a convex image side;

[0010] A fourth lens, having a positive focal power, with a convex object side and a flat or concave image side;

[0011] A fifth lens, having a negative focal power, with a concave object side and a convex image side;

[0012] The total length of the optical system satisfies the relationship: 6.6 mm < TTL < 7.2 mm, and the f-number of the optical system satisfies the relationship: 1.4 < FNO < 1.7, where TTL is the total length of the optical system and FNO is the f-number of the optical system.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: By setting the total length of the optical system to satisfy the relational expression: 6.6mm < TTL < 7.2mm, and the aperture number of the optical system to satisfy the relational expression: 1.4 < FNO < 1.7, a five-piece large-aperture optical system is made into a miniature system with a small volume and light weight. This optical system includes five spherical lenses, and the lens has a short total length, a small volume, and a large aperture. The reduction in the number of lenses is also beneficial to the light weight of the opto-mechanics.

[0014] Further, the radius of curvature of the object side surface of the first lens and the thickness of the first lens on the optical axis satisfy the relational expression: 18 < (R11 / CT1) * f < 26, where R11 is the radius of curvature of the object side surface of the first lens, CT1 is the thickness of the first lens on the optical axis, and f is the total focal length of the optical system.

[0015] Further, the air gap between the second lens and the third lens on the optical axis and the air gap between the fourth lens and the fifth lens on the optical axis satisfy the relational expression: 11 < TTL / (T23 - T45) < 24, where T23 is the air gap between the second lens and the third lens on the optical axis, and T45 is the air gap between the fourth lens and the fifth lens on the optical axis.

[0016] Further, the combined effective focal length of the first lens and the second lens and the combined effective focal length of the third lens, the fourth lens, and the fifth lens satisfy the relational expression: 1.5 < |f345 / f12| < 134, where f12 is the combined effective focal length of the first lens and the second lens, and f345 is the combined effective focal length of the third lens, the fourth lens, and the fifth lens.

[0017] Further, the field of view angle of the optical system and the total length of the optical system satisfy the relational expression: 3.7 < fov / TTL < 4.8, where fov is the field of view angle of the optical system.

[0018] Further, the outer diameter of the object side surface of the first lens, the outer diameter of the object side surface of the second lens, and the radius of curvature of the image side surface of the second lens satisfy the relational expression: -35 < (D11 + D21) * R22 / f < 6, where D11 is the outer diameter of the object side surface of the first lens, D21 is the outer diameter of the object side surface of the second lens, R22 is the radius of curvature of the image side surface of the second lens, and f is the total focal length of the optical system.

[0019] Further, the effective focal length of the second lens and the total focal length of the optical system satisfy the relational expression: -3 < f2 / f < -1;

[0020] The total length of the optical system and the total focal length of the optical system satisfy the relational expression: TTL / f <

[0021] The effective focal length of the first lens and the total focal length of the optical system satisfy the relationship: f1 / f < 0.92, where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f is the total focal length of the optical system.

[0022] Further, the radius of curvature of the object side surface of the third lens on the optical axis, the radius of curvature of the image side surface of the third lens on the optical axis, and the thickness of the fifth lens on the optical axis satisfy the relationship: R31 / (R32 * CT5) ≤ 1.1, where R31 is the radius of curvature of the object side surface of the third lens on the optical axis, R32 is the radius of curvature of the image side surface of the third lens on the optical axis, and CT5 is the thickness of the fifth lens on the optical axis.

[0023] Further, the materials of the first lens, the third lens, the fourth lens, and the fifth lens are all optical glass. The refractive index ranges of the first lens, the third lens, the fourth lens, and the fifth lens are from 1.49 to 2.05, and the Abbe number ranges of the first lens, the third lens, the fourth lens, and the fifth lens are from 19 to 70.4.

[0024] Further, the effective focal length of the optical system satisfies the relationship: 5.22 mm ≤ EFL ≤ 6.15 mm, where EFL is the effective focal length of the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the five - element large - aperture optical system according to Embodiment 1 of the present invention;

[0026] Figure 2 It is an astigmatism curve diagram of the five - element large - aperture optical system according to Embodiment 1 of the present invention;

[0027] Figure 3 It is a distortion curve diagram of the five - element large - aperture optical system according to Embodiment 1 of the present invention;

[0028] Figure 4 It is a schematic structural diagram of the five - element large - aperture optical system according to Embodiment 2 of the present invention;

[0029] Figure 5 It is an astigmatism curve diagram of the five - element large - aperture optical system according to Embodiment 2 of the present invention;

[0030] Figure 6 It is a distortion curve diagram of the five - element large - aperture optical system according to Embodiment 2 of the present invention;

[0031] Figure 7It shows a schematic structural diagram of the five-element large-aperture optical system according to Embodiment 3 of the present invention;

[0032] Figure 8 It shows an astigmatism curve graph of the five-element large-aperture optical system according to Embodiment 3 of the present invention;

[0033] Figure 9 It shows a distortion curve graph of the five-element large-aperture optical system according to Embodiment 3 of the present invention;

[0034] Figure 10 It shows a schematic structural diagram of the five-element large-aperture optical system according to Embodiment 4 of the present invention;

[0035] Figure 11 It shows an astigmatism curve graph of the five-element large-aperture optical system according to Embodiment 4 of the present invention;

[0036] Figure 12 It shows a distortion curve graph of the five-element large-aperture optical system according to Embodiment 4 of the present invention.

[0037] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0038] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0039] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature and do not represent any limitation on the feature. Therefore, without departing from the teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0040] In the drawings, for the sake of clarity, the thickness, dimensions, and shape of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn strictly to scale. [[ID=**36**]]

[0041] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the projection plane is called the projection side of the lens, and the surface of each lens closest to the image source plane is called the image source side of the lens.

[0042] It should also be understood that the terms "comprise", "comprising", "have", "including" and / or "containing", when used in this specification, denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than individual elements in the list. In addition, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0043] 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 should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0044] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0045] The five-piece large-aperture optical system of the embodiment of the present application includes a MicroLED image source and a projection lens group. Among them, the MicroLED image source can emit light by itself and carry image information. After the light emitted by it is transmitted through the projection lens group, it enters the waveguide sheet from the pupil side (object side), and finally synchronously guides the projection image and the external real ambient light to the human eye, realizing unobstructed observation of the external environment while displaying the information image.

[0046] Among them, the five-piece large-aperture optical system sequentially includes, along the optical axis from the object side to the image side: a diaphragm, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens.

[0047] In some embodiments, there is one and only one diaphragm, which may be located in front of the first lens.

[0048] In some embodiments, the first lens has a positive optical power, with its object side being convex and its image side being planar or concave.

[0049] In some embodiments, the second lens has a negative optical power, with its object side being concave and its image side being convex or concave.

[0050] In some embodiments, the third lens has a positive optical power, with its object side being convex or planar and its image side being convex.

[0051] In some embodiments, the fourth lens has a positive optical power, with its object side being convex and its image side being planar or concave.

[0052] In some embodiments, the fifth lens has a negative optical power, with its object side being concave and its image side being convex.

[0053] In some embodiments, the total length of the optical system satisfies the relation: 6.6 mm < TTL < 7.2 mm, and the f-number of the optical system satisfies the relation: 1.4 < FNO < 1.7, where TTL is the total length of the optical system and FNO is the f-number of the optical system.

[0054] The first lens, the third lens, and the fourth lens converge light rays, shortening the total length of the optical system and reducing the volume of the lens.

[0055] The object side of the second lens is concave, which can effectively refract light rays to obtain a larger picture and meet the function of magnifying and imaging the picture of the AR projection lens.

[0056] The fifth lens has a negative optical power, and the imaging-side surface of the fifth lens is convex, which can effectively refract and converge light rays.

[0057] The combination of the optical powers of the lenses in the embodiments can reduce aberrations such as astigmatism and field curvature in the optical system, improve the image quality, and at the same time make the total length of the system smaller.

[0058] In some embodiments, the radius of curvature of the object side of the first lens and the thickness of the first lens on the optical axis satisfy the relation: 18 < (R11 / CT1) * f < 26, where R11 is the radius of curvature of the object side of the first lens, CT1 is the thickness of the first lens on the optical axis, and f is the total focal length of the optical system. By making the optical system satisfy the above relation, the ratio of the radius of curvature of the object side of the first lens at the optical axis and the thickness of the first lens on the optical axis is reasonably configured, reducing the sensitivity of the first lens and thus reducing the manufacturing difficulty of the first lens.

[0059] In some embodiments, the air gap between the second lens and the third lens on the optical axis and the air gap between the fourth lens and the fifth lens on the optical axis satisfy the relationship: 11 < TTL / (T23 - T45) < 24, where T23 is the air gap between the second lens and the third lens on the optical axis, and T45 is the air gap between the fourth lens and the fifth lens on the optical axis. Reasonably setting the air gap between the second lens and the third lens on the optical axis and the air gap between the fourth lens and the fifth lens on the optical axis is beneficial to reducing the sensitivity of the lens and improving the production and assembly yield of the lens. The comprehensive control of the above expressions enables the projection lens to meet the small volume design goal while enhancing the market competitiveness of the lens.

[0060] In some embodiments, the combined effective focal length of the first lens and the second lens and the combined effective focal length of the third lens, the fourth lens, and the fifth lens satisfy the relationship: 1.5 < |f345 / f12| < 134, where f12 is the combined effective focal length of the first lens and the second lens, and f345 is the combined effective focal length of the third lens, the fourth lens, and the fifth lens. By making the optical system satisfy the above relationship, it is beneficial to reducing the design sensitivity of the optical system, enabling a reasonable configuration of the refractive powers of the individual lenses in the optical system, and improving the imaging quality of the optical system; at the same time, it is also beneficial to reducing the angle at which the light exits the optical system after being refracted by the lens group, thereby reducing the incident angle of the light on the side photosensitive element of the optical system and enhancing the photosensitive performance of the photosensitive element and improving the imaging quality of the optical system.

[0061] In some embodiments, the field of view angle of the optical system and the total length of the optical system satisfy the relationship: 3.7 < fov / TTL < 4.8, where fov is the field of view angle of the optical system. Since the projection lens is connected to the waveguide sheet, and currently available waveguide sheets on the market can only receive parallel light with a small angle, the fov in the embodiments of this patent is all < 40°, ensuring that the projected image can smoothly enter the waveguide sheet for transmission. Satisfying the above relationship can make the system have a shorter total length and a smaller volume while having a smaller fov.

[0062] In some embodiments, the outer diameter of the object side of the first lens, the outer diameter of the object side of the second lens, and the radius of curvature of the image side of the second lens satisfy the relationship: -35 < (D11 + D21) * R22 / f < 6, where D11 is the outer diameter of the object side of the first lens, D21 is the outer diameter of the object side of the second lens, R22 is the radius of curvature of the image side of the second lens, and f is the total focal length of the optical system. Reasonably setting the outer diameter of the first lens of the projection lens and the radius of curvature of the image source side surface of the second lens achieves the goals of minimizing and lightening the overall lens dimensions.

[0063] In some embodiments, the effective focal length of the second lens and the total focal length of the optical system satisfy the relational expression: -3 < f2 / f < -1; by making the optical system satisfy the above relational expression, it is beneficial for the refractive power of the second lens to be properly matched in the optical system, the surface shape design of the second lens to be more simple and flexible, the aberration to be reduced, and the overall aberration correction of the optical system and the balance of imaging quality to be simplified.

[0064] In some embodiments, the total length of the optical system and the total focal length of the optical system satisfy the relational expression: TTL / f < 1.75; by satisfying the above relational expression, the optical system has the advantage of a short total length, the volume of the projection lens can be made < 0.3 cc, the weight is also correspondingly reduced, and applying it to augmented reality glasses can improve the comfort of the wearer, having broad application prospects.

[0065] In some embodiments, the effective focal length of the first lens and the total focal length of the optical system satisfy the relational expression: f1 / f < 0.92, where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f is the total focal length of the optical system. Reasonably configuring the focal length of the first lens is beneficial for compressing the total length of the system and further reducing the volume.

[0066] In some embodiments, the radius of curvature of the object side surface of the third lens at the optical axis, the radius of curvature of the image side surface of the third lens at the optical axis, and the thickness of the fifth lens on the optical axis satisfy the relational expression: R31 / (R32 * CT5) ≤ 1.1, where R31 is the radius of curvature of the object side surface of the third lens at the optical axis, R32 is the radius of curvature of the image side surface of the third lens at the optical axis, and CT5 is the thickness of the fifth lens on the optical axis. By making the optical system satisfy the above relational expression, it is beneficial for controlling the shape of the fifth lens, reducing the processing difficulty of the fifth lens, comprehensively balancing the spherical aberration, chromatic aberration, and field curvature of the optical system, and improving the imaging quality of the optical system.

[0067] In some embodiments, the materials of the first lens, the third lens, the fourth lens, and the fifth lens are all optical glass, the refractive index ranges of the first lens, the third lens, the fourth lens, and the fifth lens are from 1.49 to 2.05, and the Abbe number ranges of the first lens, the third lens, the fourth lens, and the fifth lens are from 19 to 70.4.

[0068] In some embodiments, the effective focal length of the optical system satisfies the relational expression: 5.22 mm ≤ EFL ≤ 6.15 mm, where EFL is the effective focal length of the optical system.

[0069] It should be noted that in this application, the lens material is optical glass, which is more conducive to the temperature drift stability of the fixed-focus lens. In this application, the image source is MicroLED, which can emit light by itself and carry images, but is not limited to this. The optical lens examples in the above embodiments of this application should not be construed as limitations, and this optical lens can also be applied to other fields as needed.

[0070] The invention will be further described below with multiple embodiments. In each embodiment, the thickness, curvature radius, and material selection of each lens in the five-piece large-aperture optical system are somewhat different. For specific differences, refer to the parameter tables of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following embodiments. Any other changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0071] Embodiment 1

[0072] Please refer to Figures 1 to 3 As shown, a five-piece large-aperture optical system in Embodiment 1 of the present invention includes, along the optical axis from the object side to the image side in sequence: a diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. Among them, the five-piece large-aperture optical system further includes an image source plane S11 disposed behind the fifth lens L5.

[0073] A diaphragm ST;

[0074] The first lens L1 has a positive optical power, its object side surface S1 is a convex surface, and its image side surface S2 is a plane;

[0075] The second lens L2 has a negative optical power, its object side surface S3 is a concave surface, and its image side surface S4 is a concave surface;

[0076] The third lens L3 has a positive optical power, its object side surface S5 is a convex surface, and its image side surface S6 is a convex surface;

[0077] The fourth lens L4 has a positive optical power, its object side surface S7 is a convex surface, and its image side surface S8 is a plane;

[0078] The fifth lens L5 has a negative optical power, its object side surface S9 is a concave surface, and its image side surface S10 is a convex surface.

[0079] The relevant parameters of each lens in the five-piece large-aperture optical system in Embodiment 1 are shown in Table 1. Among them, the units of the curvature radius and thickness are both millimeters (mm), and OBJ represents the object distance, which is infinity and cannot be shown in the figure.

[0080]

[0081] Table 1

[0082] In this embodiment, according to Figure 2 and Figure 3 it can be known that the projection system given in Embodiment 1 can achieve good imaging quality.

[0083] Embodiment 2

[0084] Please refer to Figures 4 to 6 As shown, a five-piece large-aperture optical system in Embodiment 2 of the present invention, the five-piece large-aperture optical system sequentially includes, from the object side to the image side along the optical axis: a diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. Among them, the five-piece large-aperture optical system further includes an image source surface S11 disposed behind the fifth lens L5.

[0085] A diaphragm ST;

[0086] The first lens L1 has a positive optical power, its object side surface S1 is a convex surface, and its image side surface S2 is a flat surface;

[0087] The second lens L2 has a negative optical power, its object side surface S3 is a concave surface, and its image side surface S4 is a concave surface;

[0088] The third lens L3 has a positive optical power, its object side surface S5 is a flat surface, and its image side surface S6 is a convex surface;

[0089] The fourth lens L4 has a positive optical power, its object side surface S7 is a convex surface, and its image side surface S8 is a flat surface;

[0090] The fifth lens L5 has a negative optical power, its object side surface S9 is a concave surface, and its image side surface S10 is a convex surface.

[0091] The relevant parameters of each lens in the five-piece large-aperture optical system in Embodiment 2 are shown in Table 2. Among them, the units of the radius of curvature and the thickness are both millimeters (mm), and OBJ represents the object distance, which is infinity and cannot be shown in the figure.

[0092]

[0093] Table 2

[0094] In this embodiment, according to Figure 5 and Figure 6 it can be known that the projection system given in Embodiment 2 can achieve good imaging quality.

[0095] Embodiment 3

[0096] Please refer to Figures 7 to 9As shown in the figure, a five-element large-aperture optical system in Embodiment 3 of the present invention. The five-element large-aperture optical system sequentially includes, along the optical axis from the projection plane to the image source plane: a diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. Among them, the five-element large-aperture optical system further includes an image source plane S11 disposed behind the fifth lens L5.

[0097] A diaphragm ST;

[0098] A first lens L1, having a positive focal power, with its object side S1 being convex and its image side S2 being concave;

[0099] A second lens L2, having a negative focal power, with its object side S3 being concave and its image side S4 being convex;

[0100] A third lens L3, having a positive focal power, with its object side S5 being convex and its image side S6 being convex;

[0101] A fourth lens L4, having a positive focal power, with its object side S7 being convex and its image side S8 being concave;

[0102] A fifth lens L5, having a negative focal power, with its object side S9 being concave and its image side S10 being convex.

[0103] The relevant parameters of each lens in the five-element large-aperture optical system in Embodiment 3 are shown in Table 3. Among them, the units of the radius of curvature and the thickness are both millimeters (mm). OBJ represents the object distance, which is infinity and cannot be shown in the figure.

[0104]

[0105] Table 3

[0106] In this embodiment, according to Figure 8 and Figure 9 it can be known that the projection system given in Embodiment 3 can achieve good imaging quality.

[0107] Embodiment 4

[0108] Please refer to Figures 10 to 12 As shown in the figure, a five-element large-aperture optical system in Embodiment 4 of the present invention. The five-element large-aperture optical system sequentially includes, along the optical axis from the projection plane to the image source plane: a diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. Among them, the five-element large-aperture optical system further includes a protective glass G1 and an image source plane S11 sequentially disposed behind the fifth lens L5.

[0109] A diaphragm ST;

[0110] The first lens L1 has a positive optical power. Its object side S1 is convex, and its image side S2 is concave.

[0111] The second lens L2 has a negative optical power. Its object side S3 is concave, and its image side S4 is concave.

[0112] The third lens L3 has a positive optical power. Its object side S5 is convex, and its image side S6 is convex.

[0113] The fourth lens L4 has a positive optical power. Its object side S7 is convex, and its image side S8 is concave.

[0114] The fifth lens L5 has a negative optical power. Its object side S9 is concave, and its image side S10 is convex.

[0115] The relevant parameters of each lens in the five - lens large - aperture optical system in Example 4 are shown in Table 4. Among them, the units of the radius of curvature and thickness are both millimeters (mm). OBJ represents the object distance, which is infinity and cannot be shown in the figure.

[0116]

[0117] Table 4

[0118] In this embodiment, according to Figure 11 and Figure 12 it can be known that the projection system given in Example 4 can achieve good imaging quality.

[0119] Please refer to Table 5, which shows the optical characteristics corresponding to the five - lens large - aperture optical systems provided in the above four embodiments, including the relevant values corresponding to each of the foregoing expressions.

[0120]

[0121] Table 5

[0122] In summary, for the five - lens large - aperture optical system in the above embodiments of the present invention, by setting the total length of the optical system to satisfy the relational expression: 6.6mm < TTL < 7.2mm, and the f - number of the optical system to satisfy the relational expression: 1.4 < FNO < 1.7, and through the reasonable combination of the lens shapes and optical power combinations among the lenses in the optical lens, the five - lens large - aperture optical system becomes a miniature system with a small volume and light weight. This optical system includes five spherical lenses, the lens has a short total length, a small volume, a large aperture, and the reduction of the number of lenses is also beneficial to the light weight of the opto - mechanical system.

[0123] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc., mean 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 invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0124] The above-described embodiments merely represent several implementation manners of the present invention. The descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A five-piece large-aperture optical system, characterized in that, From the object side to the image side along the optical axis, it successively includes: A diaphragm; A first lens with positive optical power, whose object side is convex and image side is flat or concave; A second lens with negative optical power, whose object side is concave and image side is convex or concave; A third lens with positive optical power, whose object side is convex or flat and image side is convex; A fourth lens with positive optical power, whose object side is convex and image side is flat or concave; A fifth lens with negative optical power, whose object side is concave and image side is convex; The total length of the optical system satisfies the relation: 6.6mm < TTL < 7.2mm, and the f-number of the optical system satisfies the relation: 1.4 < FNO < 1.7, where TTL is the total length of the optical system and FNO is the f-number of the optical system.

2. The five-piece large-aperture optical system according to claim 1, wherein The relation between the curvature radius of the object side of the first lens and the thickness of the first lens on the optical axis satisfies: 18 < (R11 / CT1)*f < 26, where R11 is the curvature radius of the object side of the first lens, CT1 is the thickness of the first lens on the optical axis, and f is the total focal length of the optical system.

3. The five-piece large-aperture optical system according to claim 1, wherein, The air gap between the second lens and the third lens on the optical axis and the air gap between the fourth lens and the fifth lens on the optical axis satisfy the relation: 11 < TTL / (T23 - T45) < 24, where T23 is the air gap between the second lens and the third lens on the optical axis, and T45 is the air gap between the fourth lens and the fifth lens on the optical axis.

4. The five-piece large-aperture optical system according to claim 1, wherein The relation between the combined effective focal length of the first lens and the second lens and the combined effective focal length of the third lens, the fourth lens, and the fifth lens satisfies: 1.5 < |f345 / f12| < 134, where f12 is the combined effective focal length of the first lens and the second lens, and f345 is the combined effective focal length of the third lens, the fourth lens, and the fifth lens.

5. The five-piece large-aperture optical system according to claim 1, characterized in that, The relation between the field of view angle of the optical system and the total length of the optical system satisfies: 3.7 < fov / TTL < 4.8, where fov is the field of view angle of the optical system.

6. The five-piece large-aperture optical system according to claim 1, characterized in that, The relation between the outer diameter of the object side of the first lens, the outer diameter of the object side of the second lens, and the curvature radius of the image side of the second lens satisfies: -35 < (D11 + D21)*R22 / f < 6, where D11 is the outer diameter of the object side of the first lens, D21 is the outer diameter of the object side of the second lens, R22 is the curvature radius of the image side of the second lens, and f is the total focal length of the optical system.

7. The five-piece large-aperture optical system according to claim 1, characterized in that, The relation between the effective focal length of the second lens and the total focal length of the optical system satisfies: -3 < f2 / f < -1; The relation between the total length of the optical system and the total focal length of the optical system satisfies: TTL / f < 1.75; The relation between the effective focal length of the first lens and the total focal length of the optical system satisfies: f1 / f < 0.92, where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f is the total focal length of the optical system.

8. The five-piece large-aperture optical system according to claim 1, characterized in that, The radius of curvature of the object side surface of the third lens on the optical axis, the radius of curvature of the image side surface of the third lens on the optical axis, and the thickness of the fifth lens on the optical axis satisfy the relational expression: R31 / (R32*CT5) ≤ 1.1, where R31 is the radius of curvature of the object side surface of the third lens on the optical axis, R32 is the radius of curvature of the image side surface of the third lens on the optical axis, and CT5 is the thickness of the fifth lens on the optical axis.

9. The five-piece large-aperture optical system according to claim 1, wherein The materials of the first lens, the third lens, the fourth lens, and the fifth lens are all optical glass. The refractive index ranges of the first lens, the third lens, the fourth lens, and the fifth lens are from 1.49 to 2.05, and the Abbe number ranges of the first lens, the third lens, the fourth lens, and the fifth lens are from 19 to 70.

4.

10. The five-piece large-aperture optical system according to claim 1, wherein, The effective focal length of the optical system satisfies the relational expression: 5.22 mm ≤ EFL ≤ 6.15 mm, where EFL is the effective focal length of the optical system.

Images