Five-piece large-aperture optical system

Abstract

The invention provides a five-piece type large-aperture optical system. The five-piece type large-aperture optical system sequentially comprises a diaphragm, a first lens and a second lens from an object side to an image side along an optical axis; the first lens has positive focal power, the object side surface of the first lens is a convex surface, and the image side surface is a plane or a concave surface; the second lens has negative focal power, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface or a concave surface; the third lens has positive focal power, the object side surface of the third lens is a convex surface or a plane, and the image side surface of the third lens is a convex surface; the fourth lens has positive focal power, the object side surface of the fourth lens is a convex surface, and the image side surface is a plane or a concave surface; the fifth lens has negative focal power, the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface; the total length of the optical system meets the relational expression: 6.6 mmlt; tTLlt; the aperture number of the optical system meets the relational expression: 1.4 lt; fNOlt, FNOlt; tTL is the total length of the optical system, and FNO is the number of apertures of the optical system, so that the five-piece large-aperture optical system becomes a miniature system with small size and 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, display eyepieces directly affect the wearing experience and comfort in terms of imaging quality, weight, and size. In recent years, the 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, making it difficult to meet the development trend of lightweight and miniaturization of smart glasses. Summary of the Invention

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

[0005] The invention provides the following technical solution: 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, having a positive focal power, with its object side surface being convex and its image side surface being planar or concave; A second lens, having a negative focal power, with its object side surface being concave and its image side surface being convex or concave; A third lens, having a positive focal power, with its object side surface being convex or planar and its image side surface being convex; A fourth lens, having a positive focal power, with its object side surface being convex and its image side surface being planar or concave; A fifth lens, having a negative focal power, with its object side surface being concave and its image side surface being convex; 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.

[0006] Compared with the prior art, the beneficial effect of the present invention is that by setting the total length of the optical system to satisfy the relationship: 6.6 mm < TTL < 7.2 mm, and the f - number of the optical system to satisfy the relationship: 1.4 < FNO < 1.7, the five - element large - aperture optical system becomes a miniature system with small volume and light weight. This optical system includes five spherical lenses, the lens has a short total length, small volume, large aperture, and the reduction of the number of lenses is also beneficial to the light weight of the optical engine.

[0007] 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 relationship: 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.

[0008] 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 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.

[0009] 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 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.

[0010] Further, 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.

[0011] 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 relationship: -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.

[0012] Further, the effective focal length of the second lens and the total focal length of the optical system satisfy the relationship: -3 < f2 / f < -1; The total length of the optical system and the total focal length of the optical system satisfy the relationship: TTL / f < 1.75; 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.

[0013] Further, 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.

[0014] 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.

[0015] Further, 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. Description of the Drawings

[0016] Figure 1 It shows a schematic structural diagram of the five-element large-aperture optical system according to Embodiment 1 of the present invention; Figure 2 It shows an astigmatism curve diagram of the five-element large-aperture optical system according to Embodiment 1 of the present invention; Figure 3 It shows a distortion curve diagram of the five-element large-aperture optical system according to Embodiment 1 of the present invention; Figure 4 It shows a schematic structural diagram of the five-element large-aperture optical system according to Embodiment 2 of the present invention; Figure 5 It shows an astigmatism curve diagram of the five-element large-aperture optical system according to Embodiment 2 of the present invention; Figure 6 It shows a distortion curve diagram of the five-element large-aperture optical system according to Embodiment 2 of the present invention; Figure 7 It shows a schematic structural diagram of the five-element large-aperture optical system according to Embodiment 3 of the present invention; Figure 8 It shows an astigmatism curve diagram of the five-element large-aperture optical system according to Embodiment 3 of the present invention; Figure 9 It shows a distortion curve diagram of the five-element large-aperture optical system according to Embodiment 3 of the present invention; Figure 10 It shows a schematic structural diagram of the five-element large-aperture optical system according to Embodiment 4 of the present invention; Figure 11It represents the astigmatism curve graph of the five-element large-aperture optical system according to Embodiment 4 of the present invention; Figure 12 It represents the distortion curve graph of the five-element large-aperture optical system according to Embodiment 4 of the present invention.

[0017] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0018] 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.

[0019] 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 features. 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.

[0020] In the drawings, for the sake of clarity, the thickness, dimensions, and shapes 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 for illustrative purposes only and are not drawn to an exact scale.

[0021] In this article, 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.

[0022] It should also be understood that the terms "comprises", "comprising", "has", "including" and / or "including having", when used in this specification, indicate 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 the 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.

[0023] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (such as those defined in a common dictionary) shall 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.

[0024] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The following will detail this application with reference to the drawings and in conjunction with the embodiments.

[0025] The five-piece large-aperture optical system of the embodiments of this 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 plate from the pupil side (object side), and finally synchronously guides the projection image and the external real ambient light to the human eye, realizing the unobstructed observation of the external environment while displaying the information image.

[0026] 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.

[0027] In some embodiments, there is one and only one diaphragm, which can be located in front of the first lens.

[0028] In some embodiments, the first lens has a positive focal power, its object side surface is convex, and its image side surface is flat or concave.

[0029] In some embodiments, the second lens has a negative focal power, its object side surface is concave, and its image side surface is convex or concave.

[0030] In some embodiments, the third lens has a positive focal power, its object side surface is convex or flat, and its image side surface is convex.

[0031] In some embodiments, the fourth lens has a positive focal power, its object side surface is convex, and its image side surface is flat or concave.

[0032] In some embodiments, the fifth lens has a negative focal power, its object side surface is concave, and its image side surface is convex.

[0033] In some embodiments, 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.

[0034] 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. The object side surface 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. 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.

[0035] In the embodiment, the combination of the optical powers of the lenses 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.

[0036] In some embodiments, 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 relationship: 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. By making the optical system satisfy the above relationship, the ratio of the radius of curvature of the object side surface of the first lens at the optical axis to 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.

[0037] 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 yield of lens production and assembly. 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.

[0038] 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 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. By making the optical system satisfy the above relational expression, it is beneficial to reduce the design sensitivity of the optical system, reasonably configure the refractive power of each lens in the optical system, and improve the imaging quality of the optical system; at the same time, it is also beneficial to reduce the angle of the light exiting the optical system after being refracted by the lens group, thereby reducing the incident angle of the light into the image of the optical system. The incident angle of the side photosensitive element improves the photosensitive performance of the photosensitive element and the imaging quality of the optical system.

[0039] In some embodiments, 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. Since this 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, so 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 relational expression can make the system have a shorter total length and a smaller volume while having a smaller fov.

[0040] 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 relational expression: -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. By 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, the goal of minimizing and lightening the overall size of the lens is achieved.

[0041] 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 coordinated in the optical system, the surface shape design of the second lens is more simple and flexible, the aberration is reduced, and the aberration correction of the overall optical system and the balance of the imaging quality are simplified.

[0042] 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; satisfying the above relational expression enables the optical system to have the advantage of a short total length. The volume of the projection lens can be made < 0.3 cc, and the weight is correspondingly reduced. Applying it to augmented reality glasses can improve the comfort of the wearer and has broad application prospects.

[0043] 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 to compressing the total length of the system and further reducing the volume.

[0044] In some embodiments, the curvature radius of the object side surface of the third lens at the optical axis, the curvature radius 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 curvature radius of the object side surface of the third lens at the optical axis, R32 is the curvature radius 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 to control the shape of the fifth lens, reduce the processing difficulty of the fifth lens, comprehensively balance the spherical aberration, chromatic aberration, and field curvature of the optical system, and improve the imaging quality of the optical system.

[0045] 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.

[0046] 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.

[0047] It should be noted that in this application, the lens material is optical glass, which is more beneficial to the temperature drift stability of the fixed-focus lens. In this application, the image source is MicroLED. This image source can emit light by itself and carry images, but it is not limited thereto. The optical lens examples of 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.

[0048] The invention will be further described in multiple embodiments below. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the five-piece large-aperture optical system are slightly different. For specific differences, please refer to the parameter tables of each embodiment. The following embodiments are only the 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.

[0049] Embodiment 1 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 surface S11 disposed behind the fifth lens L5.

[0050] A diaphragm ST; The first lens L1 has a positive focal power. Its object side surface S1 is a convex surface, and its image side surface S2 is a flat surface; The second lens L2 has a negative focal power. Its object side surface S3 is a concave surface, and its image side surface S4 is a concave surface; The third lens L3 has a positive focal power. Its object side surface S5 is a convex surface, and its image side surface S6 is a convex surface; The fourth lens L4 has a positive focal power. Its object side surface S7 is a convex surface, and its image side surface S8 is a flat surface; The fifth lens L5 has a negative focal power. Its object side surface S9 is a concave surface, and its image side surface S10 is a convex surface.

[0051] 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 radius of curvature and thickness are both millimeters (mm). OBJ represents the object distance, which is infinity and cannot be shown in the figure.

[0052]

[0053] Table 1 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.

[0054] Embodiment 2 Please refer to Figures 4 to 6As shown in the figure, a five-element large-aperture optical system in Embodiment 2 of the present invention. The five-element 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-element large-aperture optical system further includes an image source plane S11 disposed behind the fifth lens L5.

[0055] A diaphragm ST; The first lens L1, having a positive focal power, with its object side surface S1 being convex and its image side surface S2 being flat; The second lens L2, having a negative focal power, with its object side surface S3 being concave and its image side surface S4 being concave; The third lens L3, having a positive focal power, with its object side surface S5 being flat and its image side surface S6 being convex; The fourth lens L4, having a positive focal power, with its object side surface S7 being convex and its image side surface S8 being flat; The fifth lens L5, having a negative focal power, with its object side surface S9 being concave and its image side surface S10 being convex.

[0056] The relevant parameters of each lens in the five-element 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). OBJ represents the object distance, which is infinity and cannot be shown in the figure.

[0057]

[0058] Table 2 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.

[0059] Embodiment 3 Please refer to Figures 7 to 9 As 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, from the projection plane to the image source plane 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-element large-aperture optical system further includes an image source plane S11 disposed behind the fifth lens L5.

[0060] A diaphragm ST; The first lens L1, having a positive focal power, with its object side surface S1 being convex and its image side surface S2 being concave; The second lens L2, having a negative focal power, with its object side surface S3 being concave and its image side surface S4 being convex; The third lens L3, having a positive focal power, with its object side surface S5 being convex and its image side surface S6 being convex; The fourth lens L4 has a positive optical power, with its object side S7 being convex and its image side S8 being concave; The fifth lens L5 has a negative optical power, with its object side S9 being concave and its image side S10 being convex.

[0061] The relevant parameters of each lens in the five - lens large - aperture optical system in Embodiment 3 are shown in Table 3, where 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.

[0062]

[0063] Table 3 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.

[0064] Embodiment 4 Please refer to Figures 10 to 12 As shown, a five - lens large - aperture optical system in Embodiment 4 of the present invention, the five - lens 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 - lens large - aperture optical system further includes a protective glass G1 and an image source plane S11 sequentially arranged behind the fifth lens L5.

[0065] A diaphragm ST; The first lens L1 has a positive optical power, with its object side S1 being convex and its image side S2 being concave; The second lens L2 has a negative optical power, with its object side S3 being concave and its image side S4 being concave; The third lens L3 has a positive optical power, with its object side S5 being convex and its image side S6 being convex; The fourth lens L4 has a positive optical power, with its object side S7 being convex and its image side S8 being concave; The fifth lens L5 has a negative optical power, with its object side S9 being concave and its image side S10 being convex.

[0066] The relevant parameters of each lens in the five - lens large - aperture optical system in Embodiment 4 are shown in Table 4, where 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.

[0067]

[0068] Table 4 In this embodiment, according to Figure 11 andFigure 12 It can be seen that the projection system given in Embodiment 4 can achieve good imaging quality.

[0069] Please refer to Table 5, which shows the optical characteristics corresponding to the five-piece large-aperture optical systems provided in the above four embodiments, including the relevant values corresponding to each of the foregoing expressions.

[0070]

[0071] Table 5 In summary, for the five-piece large-aperture optical system in the above embodiments of the present invention, by setting the total length of the optical system to satisfy the relationship: 6.6 mm < TTL < 7.2 mm, and the f-number of the optical system to satisfy the relationship: 1.4 < FNO < 1.7, and by reasonably matching the lens shapes and the combination of optical powers between the lenses, the five-piece large-aperture optical system becomes a miniature system with a small volume and a 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-mechanical system.

[0072] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", 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 representations 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 any one or more embodiments or examples in a suitable manner.

[0073] The above-described embodiments merely represent several implementation manners of the present invention. Their 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 should be subject to the appended claims.

Claims

1. A five-piece large-aperture optical system, characterized in that, It successively 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 flat 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 flat and whose image side is convex; A fourth lens with a positive focal power, whose object side is convex and whose image side is flat 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: 6.6mm < 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, characterized in that, 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, wherein 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, wherein The curvature radius of the object side surface of the third lens on the optical axis, the curvature radius 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 curvature radius of the object side surface of the third lens on the optical axis, R32 is the curvature radius 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, characterized in that, 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.

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