Optical lens

Abstract

The present invention provides an optical lens comprising four lenses and a folding reflective element. The lens comprises, in order from the object side to the image plane along the direction of light transmission: a first lens having positive optical power, whose object-side surface is convex and whose image-side surface is concave; a second lens having optical power, whose object-side surface is convex and whose image-side surface is concave; a third lens having positive optical power; a fourth lens having optical power, whose object-side surface is convex and whose image-side surface is concave; the folding reflective element comprising a light incident surface, a first reflecting surface, a second reflecting surface, a third reflecting surface, and a light exiting surface, all of which are planes, wherein the light incident surface, the second reflecting surface, and the light exiting surface are substantially the same plane; and the optical axes of the optical lens comprising a first optical axis, a second optical axis, a third optical axis, and a fourth optical axis. The optical lens provided by the present invention can achieve excellent periscope telephoto photography effects and has one or more advantages, including miniaturization, a large image plane, a large aperture, and high-quality imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging lenses, and in particular to an optical lens. Background Art

[0002] Telephoto cameras can meet consumers' needs for shooting specific targets, but the total optical length of traditional telephoto cameras is too large and does not meet the lightweight design requirements of smartphones.

[0003] To empower mobile photography with more powerful telephoto and long-focus capabilities, periscope lenses have been a hot topic since their inception and have become standard equipment in some flagship imaging phones. The pursuit of higher-quality, more stable telephoto performance requires a larger optical system aperture and greater light throughput. However, after the optical path of a periscope telephoto lens deflects through reflective elements such as prisms, the lens aperture is limited by the thickness of the phone and cannot be increased, hindering the development of high-quality telephoto lenses. Summary of the Invention

[0004] In view of the above problems, the object of the present invention is to provide an optical lens that can achieve a telephoto periscope effect and has the characteristics of excellent imaging quality.

[0005] The technical solution adopted in the present invention is:

[0006] An optical lens, consisting of four lenses and a reflective element, includes the following elements in order from the object side to the imaging surface along the light transmission direction:

[0007] The first lens has positive refractive power, its object-side surface is convex and its image-side surface is concave;

[0008] a second lens having optical power, wherein the object-side surface thereof is convex and the image-side surface thereof is concave;

[0009] a third lens having positive optical power;

[0010] a fourth lens having optical power, the object-side surface of which is convex and the image-side surface of which is concave;

[0011] A folding and reflecting element, comprising a light incident surface, a first reflecting surface, a second reflecting surface, a third reflecting surface, and a light emitting surface, all of which are planes, wherein the light incident surface, the second reflecting surface, and the light emitting surface are substantially the same plane;

[0012] The optical axis of the optical lens includes a first optical axis, a second optical axis, a third optical axis, and a fourth optical axis. The optical path passes through the first lens, the second lens, the third lens, and the fourth lens along the first optical axis and enters the catadioptric element, passes through the light incident surface to the first reflection surface, is reflected to the second reflection surface, is then totally reflected to the third reflection surface, and is further reflected to the light exit surface and exits to the imaging surface; the first reflection surface deflects the optical path from the first optical axis to the second optical axis, the second reflection surface deflects the optical path from the second optical axis to the third optical axis, and the third reflection surface deflects the optical path from the third optical axis to the fourth optical axis; the fourth optical axis is perpendicular to the imaging surface; the first optical axis and the fourth optical axis are parallel;

[0013] Wherein, the true image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens satisfy: 4.5 < ((43.26 / IH) × f) / 23 < 5.5.

[0014] Further preferably, the distance LY perpendicular to the first optical axis between the intersection point of the object side surface of the first lens on the first optical axis and the intersection point of the imaging surface on the fourth optical axis and the maximum displacement amount LZ parallel to the first optical axis of the optical path from the object side surface of the first lens to the imaging surface satisfy: 0.7 < LY / LZ < 0.9.

[0015] Further preferably, the distance LY perpendicular to the first optical axis between the intersection point of the object side surface of the first lens on the first optical axis and the intersection point of the imaging surface on the fourth optical axis and the total distance TTL passed along the first optical axis, the second optical axis, the third optical axis, and the fourth optical axis from the object side surface of the first lens to the imaging surface satisfy: 0.32 < LY / TTL < 0.4; the maximum displacement amount LZ parallel to the first optical axis of the optical path from the object side surface of the first lens to the imaging surface and the total distance TTL passed along the first optical axis, the second optical axis, the third optical axis, and the fourth optical axis from the object side surface of the first lens to the imaging surface satisfy: 0.42 < LZ / TTL < 0.47.

[0016] Further preferably, the included angle θ between the first optical axis and the second optical axis satisfies: 54° < θ < 64°.

[0017] Further preferably, the effective aperture DM11 of the first lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: <0.95 < DM11 / IH < 1.1.

[0018] Further preferably, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 0.45 < f1 / f < 2.7; the edge thickness ET1 of the first lens and the central thickness CT1 of the first lens satisfy: 0.32 < ET1 / CT1 < 0.62.

[0019] Further preferably, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.4 < f3 / f < 2.8.

[0020] Further preferably, the focal length f1 of the first lens and the focal length f3 of the third lens satisfy: 0.5 < f1 / f3 < 3.5.

[0021] Further preferably, the distance TL on the first optical axis from the object side surface of the first lens to the light incident surface of the refractive element and the thickness LG of the refractive element equivalent to a flat glass satisfy: 0.3 < TL / LG < 0.5.

[0022] Further preferably, the true image height IH corresponding to the maximum field angle of the optical lens and the F-number Fno of the optical lens satisfy: 3.3 mm < IH / Fno < 4.1 mm.

[0023] Compared with the prior art, the optical lens provided by the present invention can achieve excellent effects of periscope telephoto shooting through the arrangement of four conventional lenses and one refractive element, and has one or more advantages such as a large image plane, a large aperture, and high-quality imaging, greatly improving the user experience. At the same time, since the optical path turns three times inside the refractive element, the volume of the folded optical system is greatly compressed, and while achieving a good telephoto shooting effect of the lens, the total length of the optical lens is greatly reduced, and the miniaturization of the lens is preferably achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:

[0025] Figure 1 is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0026] In the figure, LY is the distance perpendicular to the first optical axis between the intersection point of the object side surface of the first lens on the first optical axis and the intersection point of the imaging surface on the fourth optical axis; LZ is the maximum displacement of the optical path from the object side surface of the first lens to the imaging surface parallel to the first optical axis; θ is the angle between the first optical axis and the second optical axis.

[0027] Figure 2 is the distortion curve diagram of the optical lens in Embodiment 1 of the present invention.

[0028] Figure 3 4 is an astigmatism curve diagram of the optical lens in Example 1 of the present invention.

[0029] Figure 4 Graph showing the magnification chromatic aberration of the optical lens in Example 1 of the present invention.

[0030] Figure 5 1 is an axial aberration curve diagram of the optical lens in Example 1 of the present invention.

[0031] Figure 6 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0032] Figure 7 This is a distortion curve diagram of the optical lens in Example 2 of the present invention.

[0033] Figure 8 Graph showing the astigmatism of the optical lens in Example 2 of the present invention.

[0034] Figure 9 2 is a graph showing the magnification chromatic aberration curve of the optical lens in Example 2 of the present invention.

[0035] Figure 10 2 is an axial aberration curve diagram of the optical lens in Example 2 of the present invention.

[0036] Figure 11 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0037] Figure 12 2 is a distortion curve diagram of the optical lens in Example 3 of the present invention.

[0038] Figure 13 4 is an astigmatism curve diagram of the optical lens in Example 3 of the present invention.

[0039] Figure 14 Graph showing the magnification chromatic aberration of the optical lens in Example 3 of the present invention.

[0040] Figure 15 4 is an axial aberration curve diagram of the optical lens in Example 3 of the present invention.

[0041] Figure 16 Schematic diagram of the structure of the optical lens in Example 4 of the present invention.

[0042] Figure 17 This is a distortion curve diagram of the optical lens in Example 4 of the present invention.

[0043] Figure 18 4 is an astigmatism curve diagram of the optical lens in Example 4 of the present invention.

[0044] Figure 19 Graph showing the magnification chromatic aberration of the optical lens in Example 4 of the present invention.

[0045] Figure 20 4 is an axial aberration curve diagram of the optical lens in Example 4 of the present invention.

[0046] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0047] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of embodiments of the present application and are not intended to 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.

[0048] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of the present invention.

[0049] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0050] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0051] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," 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 expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0052] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0053] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] The optical lens provided in an embodiment of the present invention is composed of four lenses and a folding reflective element, and includes, in order from the object side to the imaging surface along the direction of light transmission: a first lens, a second lens, a third lens, a fourth lens and a folding reflective element.

[0055] Among them, the first lens may have positive optical power, its object side surface is convex, and its image side surface is concave. The second lens may have positive optical power or negative optical power, its object side surface is convex, and its image side surface is concave. The third lens may have positive optical power, its object side surface may be concave or convex, and its image side surface may be concave or convex. The fourth lens may have positive optical power or negative optical power, its object side surface is convex, and its image side surface is concave. The refractive element includes a light incident surface, a first reflecting surface, a second reflecting surface, a third reflecting surface, and a light exit surface, all of which are planes, wherein the light incident surface, the second reflecting surface, and the light exit surface are essentially the same plane. By setting the refractive element, the light path can make multiple turns inside the refractive element, greatly increasing the propagation path of the light, making the spatial configuration more flexible, and facilitating the compression of the volume of the folded optical system to achieve a telephoto periscope-style imaging effect. More specifically, the refractive element can adopt a prism structure.

[0056] In the present invention, the optical axis of the optical lens includes a first optical axis, a second optical axis, a third optical axis, and a fourth optical axis. The first lens, the second lens, the third lens, and the fourth lens may be located on the first optical axis. The light path passes through the first lens, the second lens, the third lens, and the fourth lens along the first optical axis and enters the refractive element. The light path passes through the light incident surface to the first reflective surface, is reflected to the second reflective surface, is then totally reflected to the third reflective surface, and is then reflected to the light exit surface and emitted to the imaging surface. The first reflective surface redirects the light path from the first optical axis to the second optical axis, the second reflective surface redirects the light path from the second optical axis to the third optical axis, and the third reflective surface redirects the light path from the third optical axis to the fourth optical axis.

[0057] Please refer to Figure 1As shown, the light path makes three turns in the refracting element, wherein total reflection of the light occurs on the second reflective surface. Reflection occurs on the first reflective surface and the third reflective surface. It can be understood that the first reflective surface and the third reflective surface have a reflective coating or are mirror surfaces. At the same time, the positional relationship of the surfaces where the first, second, and third reflective surfaces are located is determined by the angle between the optical axes, and the angle between the optical axes can be set according to the space requirements and the requirements of the refracting light path. Specifically, the first optical axis and the fourth optical axis are parallel, the fourth optical axis is perpendicular to the imaging plane, the angle between the third optical axis and the fourth optical axis is the same as the angle between the first optical axis and the second optical axis; the angle between the second optical axis and the third optical axis is twice the angle between the first optical axis and the second optical axis; the first optical axis can be perpendicular to the light incident surface of the refracting element.

[0058] In some embodiments, the optical lens may further include an aperture, which may be located between the object side and the first lens. It is understood that the aperture is used to limit the amount of light entering to change the brightness of the image.

[0059] In some embodiments, the optical lens may further include a filter disposed between the folding and reflecting element and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0060] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective focal length f of the optical lens satisfy the following relationship: 4.5 < ((43.26 / IH) × f) / 23 < 5.5. This conditional equation is a formula for calculating magnification. Meeting this condition indicates that the optical lens can achieve high-magnification, ultra-telephoto photography effects of 4x to 6x. This not only provides an extremely large imaging target area but also an extremely long focal length, effectively meeting the requirements of periscope-style telephoto photography.

[0061] In some embodiments, the distance LY perpendicular to the first optical axis between the intersection of the object side surface of the first lens on the first optical axis and the intersection of the imaging plane on the fourth optical axis and the maximum displacement LZ of the light path from the object side surface of the first lens to the imaging plane parallel to the first optical axis satisfies: 0.7 <LY / LZ<0.9。 Figure 1 The figure shows a schematic diagram of LY and LZ. It can also be seen from the figure that the values ​​of LY and LZ directly determine the size of the optical lens in the height and thickness directions of the electronic device it is mounted on. When these conditions are met, by controlling the ratio of the lens in the LY and LZ directions, the height and thickness ratio of the folded optical lens can be adjusted, which helps to control the overall size ratio of the folded optical lens to better match the space configuration requirements of lightweight electronic devices.

[0062] In some embodiments, the distance LY perpendicular to the first optical axis between the intersection point of the object side surface of the first lens on the first optical axis and the intersection point of the imaging surface on the fourth optical axis and the distance TTL that the object side surface of the first lens travels to the imaging surface along the first optical axis, the second optical axis, the third optical axis, and the fourth optical axis satisfy: 0.32 < LY / TTL < 0.4; the maximum displacement amount LZ parallel to the first optical axis of the optical path traveling from the object side surface of the first lens to the imaging surface and the distance TTL that the object side surface of the first lens travels to the imaging surface along the first optical axis, the second optical axis, the third optical axis, and the fourth optical axis satisfy: 0.42 < LZ / TTL < 0.47. By satisfying the above conditions, by controlling the optical path of the optical path folding and reflecting element (prism) and reasonably setting the angle between the reflecting surface and the incident surface in the folding and reflecting element, not only can the LZ direction not be too large, but also the size of LY can be controlled, achieving a balance in the LY and LZ directions, which is beneficial to the miniaturization of the lens module to better match the spatial configuration requirements of thin and light electronic devices.

[0063] In some embodiments, the angle θ between the first optical axis and the second optical axis satisfies: 54° < θ < 64°. Further, the angle θ between the first optical axis and the second optical axis satisfies: 55° < θ < 62°. By satisfying the above conditions, by reasonably setting the angle between the first and second optical axes, the light can undergo total internal reflection on the second reflecting surface after entering the second reflecting surface from the first reflecting surface of the folding and reflecting element, while making the folding and reflecting element have good processability and reducing the volume of the folding and reflecting element. The angle between the first and second optical axes depends on the spatial configuration and the refractive index of the material of the selected folding and reflecting element. When this angle is determined, the angles of the planes where the respective surfaces of the folding and reflecting element (such as the light incident surface, the first, second, and third reflecting surfaces, and the light exit surface) are located are immediately determined and can be set according to requirements in actual applications. Specifically, if the angles between the first and second optical axes and between the third and fourth optical axes are both θ, then the angle between the second and third optical axes is 2θ; since the light is reflected on the first and third reflecting surfaces and undergoes total internal reflection on the second reflecting surface, it can be further obtained that the angle between the plane where the first reflecting surface is located and the plane where the second reflecting surface is located is θ / 2, the angle between the plane where the second reflecting surface is located and the plane where the third reflecting surface is located is also θ / 2, and the angle between the plane where the first reflecting surface is located and the plane where the third reflecting surface is located is (180° - θ). It should be noted that on the basis of not affecting the reflection of the light in the marginal field of view, the prism corners formed by the first and third reflecting surfaces and the plane where the second reflecting surface is located in the folding and reflecting element can be cut, or the prism corners formed by the planes where the first and third reflecting surfaces are located can be cut. There is no light folding in the cut prism corners, which will not affect the overall light turning effect, but can minimize the size of the folding and reflecting element, thereby reducing the overall size of the optical lens.

[0064] In some embodiments, the effective aperture DM11 of the first lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 0.95 < DM11 / IH < 1.1. Meeting the above conditions can make the lens have a larger light entrance aperture, ensure that the lens has a larger light flux, facilitate the realization of the large aperture performance, and at the same time can match a larger imaging target surface to achieve high-pixel imaging of the lens.

[0065] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 0.45 < f1 / f < 2.7. Meeting the above conditions, by setting the first lens to have a large positive refractive power, the first lens can converge as many incident light rays as possible, and will not introduce overly serious aberrations while compressing the total length of the optical lens.

[0066] In some embodiments, the edge thickness ET1 of the first lens and the center thickness CT1 of the first lens satisfy: 0.32 < ET1 / CT1 < 0.62. Meeting the above conditions, by adjusting the edge thickness ratio of the first lens, it helps to balance between reducing the manufacturing difficulty and reducing the stray light inside the lens.

[0067] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.4 < f3 / f < 2.8. Meeting the above conditions, by setting the third lens to have a large positive refractive power, the light rays can be further converged so that the light rays enter the catadioptric element with a smaller aperture.

[0068] In some embodiments, the focal length f1 of the first lens and the focal length f3 of the third lens satisfy: 0.5 < f1 / f3 < 3.5. Meeting the above conditions, by reasonably setting the focal length relationship between the first and third lenses, it is beneficial to the smooth transition of light rays, and at the same time corrects various aberrations of the optical lens, improving the imaging quality of the optical lens.

[0069] In some embodiments, the distance TL on the first optical axis from the object side surface of the first lens to the light incident surface of the catadioptric element and the thickness LG of the catadioptric element equivalent to a flat glass satisfy: 0.3 < TL / LG < 0.5. It can be understood that LG is the sum of the lengths of the first, second, third, and fourth optical axes inside the catadioptric element. Meeting the above conditions, by setting a smaller lens group length and a longer folded optical path length, it is beneficial to the folding of the optical path of the optical lens, and better realizes the miniaturization of the lens volume.

[0070] In some embodiments, the true image height IH corresponding to the maximum field angle of view of the optical lens and the F-number Fno of the optical lens satisfy: 3.3 mm < IH / Fno < 4.1 mm. Meeting the above conditions, by controlling the image height and F-number of the lens, it is possible to ensure that the lens has a large image plane while having a larger light transmission amount, which is beneficial to the implementation of optical anti-shake technology in the periscope telephoto module and improves the imaging quality of the optical lens.

[0071] In some embodiments, the combined focal length f234 of the second lens, the third lens and the fourth lens and the effective focal length f of the optical lens satisfy: -1.2 < f234 / f < 5. Meeting the above conditions, by reasonably setting the proportion of the combined focal length of the latter three lenses, it is beneficial to control the incident light height of the light entering the catadioptric element, beneficial to reducing the volume of the catadioptric element, and further realizing the thinning and lightening of the lens.

[0072] In some embodiments, the thickness LG of the catadioptric element equivalent to a flat glass satisfies: 18 mm < LG < 23 mm; specifically, LG is the sum of the lengths of the first, second, third and fourth optical axes in the catadioptric element. And the thickness LG of the catadioptric element equivalent to a flat glass and the distance TTL passed by the object side surface of the first lens to the imaging surface along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis satisfy: 0.6 < LG / TTL < 0.75. Meeting the above conditions, by reasonably planning the propagation path length of the folded optical path in the catadioptric element, while meeting the telephoto design of the optical lens, the occupied space of the catadioptric element can be effectively compressed, meeting the product requirements of thinning and lightening.

[0073] In some embodiments, the refractive index Nd5 of the catadioptric element satisfies: 1.5 < Nd5 < 1.8. Meeting the above conditions, by setting the catadioptric element to have a suitable refractive index, the refractive index values of the catadioptric element and air can have a sufficient difference, so as to adjust the critical angle to ensure total internal reflection of light on the second reflection surface of the catadioptric element.

[0074] In some embodiments, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.03 < BFL / f < 0.15. Meeting the above conditions, the lens can have an appropriate back focus, ensuring the compatibility between the lens and the fuselage while making the structure of the lens more compact.

[0075] In some embodiments, the curvature radius R1 of the object side surface of the first lens and the curvature radius R2 of the image side surface of the first lens satisfy: 0.1 < R1 / R2 < 0.8. Meeting the above conditions, by reasonably setting the surface type of the first lens, the optical path control ability of the light incident surface of the first lens can be strengthened, realizing a large degree of convergence of the incident light, and reducing the difficulty of subsequent aberration correction.

[0076] In some embodiments, the radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: 0.2 < R3 / R4 < 3.5. Meeting the above conditions, by reasonably setting the surface shape of the second lens, it helps to adjust the optical path to improve the image quality.

[0077] In some embodiments, the radius of curvature R8 of the image side surface of the fourth lens and the effective focal length f of the optical lens satisfy: 0.1 < R8 / f < 0.3. Meeting the above conditions, by setting the surface shape of the image side surface of the fourth lens, the outgoing light can be refracted to a greater extent, shortening the distance from the light to the imaging surface, which is beneficial to reducing the total length of the optical lens.

[0078] In some embodiments, the chief ray angle of incidence CRA at the maximum image height of the optical lens satisfies: 14° < CRA < 16°. Meeting the above conditions, the optical lens can have a smaller CRA (not greater than 16°), and a smaller CRA is beneficial to improving the matching degree of the lens with the ultra-long focal length SENSOR (imaging chip) and improving the imaging clarity.

[0079] In some embodiments, the distance LY perpendicular to the first optical axis between the intersection point of the object side surface of the first lens on the first optical axis and the intersection point of the imaging surface on the fourth optical axis satisfies: 10 mm < LY < 12.5 mm. LY is the linear distance in the vertical direction between the first optical axis and the fourth optical axis. The parameters LY and LZ can refer to the markings in the schematic Figure 1 diagram. Controlling the value of the optical lens in the LY direction within a certain range is beneficial to the spatial setting of the SENSOR and is also beneficial to the miniaturization of the lens volume.

[0080] In some embodiments, the maximum displacement amount LZ of the optical path parallel to the first optical axis from the object side surface of the first lens to the imaging surface satisfies: 13 mm < LZ < 14.5 mm. Meeting the above conditions, the length of the folded optical system in the first optical axis direction can be adjusted, that is, the size of the lens in the thickness direction of the electronic device on which it is mounted can be reduced, which helps to make the folded optical system thinner to achieve a wider range of applications.

[0081] In some embodiments, the optical lens satisfies the conditional formula: 24 mm < f < 27 mm, 20° < FOV < 22°, 29 mm < TTL < 32 mm, 2.5 < Fno < 2.65, 9 mm < IH < 10.5 mm; where f represents the effective focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, TTL represents the distance passed along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis from the object side surface of the first lens to the imaging surface, Fno represents the aperture value of the optical lens, and IH represents the true image height corresponding to the maximum field of view angle of the optical lens. The optical lens provided by the embodiments of the present invention has at least the characteristics of long focal length (super telephoto), large aperture, large image plane, etc.

[0082] In some embodiments, the material of the lens and the reflective element in the optical lens provided by the present invention may be glass or plastic. When the material of the lens and the reflective element is plastic, the production cost can be effectively reduced. In addition, when the material of the lens and the reflective element is glass, the low dispersion characteristic of the glass itself can be used to effectively correct the geometric chromatic aberration of the optical system. In the optical lens provided by the present invention, the first lens and the reflective element can be made of glass; the second lens, the third lens and the fourth lens can be made of plastic, which not only makes the lens have excellent imaging performance, but also makes the structure of the lens more compact, and can better achieve a balance between miniaturization of the lens and high image quality.

[0083] In some embodiments, the first, second, third, and fourth lenses may be spherical or aspherical lenses. Compared to spherical structures, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number and size of lenses, and further achieving lens miniaturization. More specifically, the first, second, third, and fourth lenses of the present invention may all be aspherical lenses, which can effectively reduce the aberrations of the optical lens, thereby reducing the number and size of lenses, and further achieving lens miniaturization.

[0084] In various embodiments of the present invention, when the lens is an aspheric lens, the surface shape of the aspheric lens satisfies the following equation:

[0085] ;

[0086] Among them, z is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis, c is the paraxial curvature of the surface, k is the quadratic surface coefficient, and A 2i is the 2i-th order aspheric surface coefficient.

[0087] The present invention is further illustrated below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens vary; for details, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Any other changes, substitutions, combinations, or simplifications that do not deviate from the novelties of the present invention shall be considered equivalent replacements and are included within the scope of protection of the present invention.

[0088] Example 1

[0089] See also Figure 1 , Figure 1This is a schematic structural diagram of the optical lens 100 provided in Example 1 of the present invention. The optical lens includes, in order from the object side to the imaging surface along the light transmission direction: an aperture ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a folding element Pr and a filter G1.

[0090] The first lens L1 has positive refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave;

[0091] The second lens L2 has positive refractive power, its object-side surface S3 is convex, and its image-side surface S4 is concave;

[0092] The third lens L3 has positive refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave;

[0093] The fourth lens L4 has negative refractive power, its object-side surface S7 is convex, and its image-side surface S8 is concave;

[0094] The folding and reflecting element Pr includes a light incident surface S9, a first reflecting surface S10, a second reflecting surface S11, a third reflecting surface S12 and a light emitting surface S13, all of which are planes. The light incident surface S9, the second reflecting surface S11 and the light emitting surface S13 are substantially the same plane.

[0095] The light path follows the first optical axis OA1 through the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4, entering the refractive index element Pr. The light then passes through the incident surface S9 onto the first reflective surface S10, where it is reflected by the second reflective surface S11. It is then totally reflected by the third reflective surface S12, and then reflected by the light exit surface S13. The light then passes through the filter G1 and reaches the imaging plane. The first reflective surface S10 redirects the light path from the first optical axis OA1 to the second optical axis OA2. The second reflective surface S11 redirects the light path from the second optical axis OA2 to the third optical axis OA3. The third reflective surface S12 redirects the light path from the third optical axis OA3 to the fourth optical axis OA4 (the fourth optical axis OA4 is perpendicular to the imaging plane). The light path undergoes three deflections within the refractive index element Pr, with total internal reflection occurring at the second reflective surface S11. Reflection occurs on the first and third reflective surfaces S10 and S12, so these surfaces are either coated or mirrored.

[0096] Specifically, if Figure 1As shown, the angle θ between the first optical axis OA1 and the second optical axis OA2 is 56°; the angle between the third optical axis OA3 and the fourth optical axis OA4 is the same as the angle between the first optical axis OA1 and the second optical axis OA2, which is also 56°; the angle between the second optical axis OA2 and the third optical axis OA3 is twice the angle between the first optical axis OA1 and the second optical axis OA2, that is, 112°; the first optical axis OA1 and the fourth optical axis OA4 are parallel. LY represents the distance perpendicular to the first optical axis between the intersection of the object side surface of the first lens on the first optical axis and the intersection of the imaging plane on the fourth optical axis, that is, the shortest distance between the first and fourth optical axes, and LY is 11.794 mm. LZ represents the maximum displacement of the light path from the object side surface of the first lens to the imaging plane parallel to the first optical axis, and LZ is 13.578 mm.

[0097] In this embodiment, the angle θ between the first and second optical axes can be determined based on the spatial configuration and the refractive index of the material of the selected reflective element Pr. Once the angle θ is determined, the angles of the planes in which the various surfaces of the reflective element Pr (such as the light incident surface S9, the first, second, and third reflective surfaces S10, S11, and S12, and the light exit surface S13) are located are also determined. In actual applications, this angle can be set as needed. Specifically, if the angle between the first and second optical axes and the angle θ between the third and fourth optical axes are both 56°, then the angle between the second and third optical axes is 2θ=112°; since the light is reflected on the first reflection surface S10 and the third reflection surface S12 and is totally reflected on the second reflection surface S11, it can be further concluded that the angle between the plane where the first reflection surface S10 is located and the plane where the second reflection surface S11 is located is θ / 2=28°, the angle between the plane where the second reflection surface S11 is located and the plane where the third reflection surface S12 is located is θ / 2=28°, and the angle between the plane where the first reflection surface S10 is located and the plane where the third reflection surface S12 is located is (180°-θ)=124°. It should be noted that, without affecting the reflection of the edge field of view light, the prism corners formed by the first and third reflection surfaces and the plane where the second reflection surface is located in the refracting element can be cut, and the prism corners formed by the planes where the first and third reflection surfaces are located can also be cut. The cut prism corners ( Figure 1 There is no light reflection in the prism corners (shown by the dotted line in the middle), which will not affect the overall light turning effect, but can minimize the size of the reflective element, thereby reducing the overall size of the optical lens.

[0098] The first lens L1 is a glass aspheric lens; the second lens L2, the third lens L3, and the fourth lens L4 are all plastic aspheric lenses; the reflective element Pr can be designed as a polygonal folding prism and can be made of glass.

[0099] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0100] Table 1-1

[0101]

[0102] The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0103] Table 1-2

[0104]

[0105] In this embodiment, the distortion curve, astigmatism curve, magnification chromatic aberration curve, and axial aberration curve of the optical lens 100 are respectively as follows: Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 shown.

[0106] Figure 2 The distortion curve of Example 1 is shown, which shows the distortion of light of different wavelengths at different image heights on the imaging surface. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the image height (unit: mm). As can be seen from the figure, the distortion of the optical lens is controlled within 0-1.5%, indicating that the optical lens 100 is capable of effectively correcting distortion.

[0107] Figure 3 The astigmatism curve of Example 1 is shown, which shows the astigmatism of light rays on the meridional image plane and the sagittal image plane. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the image height (unit: °). As can be seen from the figure, the astigmatism of the meridional image plane and the sagittal image plane is controlled within a range of -0.1mm to 0, indicating that the optical lens 100 can effectively correct astigmatism.

[0108] Figure 4 The following graph shows the magnification chromatic aberration curve for Example 1, which shows the chromatic aberration of each wavelength relative to the center wavelength (550nm) at different image heights on the imaging surface. The horizontal axis represents the chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field of view angle. As can be seen from the graph, the chromatic aberration between the longest and shortest wavelengths is controlled within ±1.5μm, indicating that the optical lens 100 is capable of excellent chromatic aberration correction.

[0109] Figure 5 The axial aberration curve of Example 1 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ±0.04mm, indicating that the optical lens 100 is able to correct the axial aberration well.

[0110] Example 2

[0111] See also Figure 6 , which is a schematic structural diagram of an optical lens 200 provided in Example 2 of the present invention. This embodiment is substantially the same as Example 1, and the light deflection and transmission paths are also substantially the same. The main differences are: the second lens element L2 has negative optical power; the fourth lens element L4 has positive optical power; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different. In this embodiment, the angle θ between the first optical axis OA1 and the second optical axis OA2 is 60°; the angle between the third optical axis OA3 and the fourth optical axis OA4 is the same as the angle between the first optical axis OA1 and the second optical axis OA2, also 60°; the angle between the second optical axis OA2 and the third optical axis OA3 is twice the angle between the first optical axis OA1 and the second optical axis OA2, that is, 120°; and the first optical axis OA1 and the fourth optical axis OA4 are parallel. Wherein, LY is 10.963 mm, and LZ is 13.815 mm.

[0112] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0113] Table 2-1

[0114]

[0115] The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0116] Table 2-2

[0117]

[0118] In this embodiment, the distortion curve, astigmatism curve, magnification chromatic aberration curve, and axial aberration curve of the optical lens 200 are respectively as follows: Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 shown.

[0119] from Figure 7 It can be seen from the figure that the distortion of the optical lens is controlled within 0~1%, indicating that the optical lens 200 can correct the distortion well.

[0120] from Figure 8 It can be seen from the figure that the astigmatism of the meridional image plane and the sagittal image plane is controlled within ±0.05 mm, indicating that the optical lens 200 can correct the astigmatism well.

[0121] from Figure 9 As can be seen from the figure, the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1.5 μm, indicating that the optical lens 200 can correct chromatic aberration very well.

[0122] from Figure 10It can be seen from the figure that the offset of the axial aberration is controlled within ±0.04 mm, indicating that the optical lens 200 can correct the axial aberration well.

[0123] Example 3

[0124] See also Figure 11 , shown is a schematic structural diagram of an optical lens 300 provided in Example 3 of the present invention. This embodiment is substantially the same as Example 1, and the light deflection and transmission paths are also substantially the same. The main differences are: the second lens element L2 has negative optical power; the object-side surface S5 of the third lens element L3 is concave at the near optical axis; the image-side surface S6 of the third lens element L3 is convex at the near optical axis; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different; in this embodiment, the angle θ between the first optical axis OA1 and the second optical axis OA2 is 60°; the angle between the third optical axis OA3 and the fourth optical axis OA4 is the same as the angle between the first optical axis OA1 and the second optical axis OA2, also 60°; the angle between the second optical axis OA2 and the third optical axis OA3 is twice the angle between the first optical axis OA1 and the second optical axis OA2, that is, 120°; and the first optical axis OA1 and the fourth optical axis OA4 are parallel. Wherein, LY is 11.124 mm, and LZ is 14.118 mm.

[0125] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0126] Table 3-1

[0127]

[0128] The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0129] Table 3-2

[0130]

[0131] In this embodiment, the distortion curve, astigmatism curve, magnification chromatic aberration curve, and axial aberration curve of the optical lens 300 are respectively as follows: Figure 12 、 Figure 13 、 Figure 14 、 Figure 15 shown.

[0132] from Figure 12 It can be seen that the distortion of the optical lens is controlled within 0~1%, indicating that the optical lens 300 can correct the distortion well.

[0133] from Figure 13 It can be seen from the figure that the astigmatism of the meridional image plane and the sagittal image plane is controlled within ±0.05 mm, indicating that the optical lens 300 can correct the astigmatism well.

[0134] from Figure 14 As can be seen from the figure, the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1.5 μm, indicating that the optical lens 300 can correct chromatic aberration very well.

[0135] from Figure 15 It can be seen from the figure that the offset of the axial aberration is controlled within ±0.04 mm, indicating that the optical lens 300 can correct the axial aberration well.

[0136] Example 4

[0137] See also Figure 16 , shown is a schematic structural diagram of an optical lens 400 provided in Example 4 of the present invention. This embodiment is substantially the same as Example 1, and the light deflection and transmission paths are also substantially the same. The main differences are: the second lens element L2 has negative optical power; the image-side surface S6 of the third lens element L3 is convex near the optical axis; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different; in this embodiment, the angle θ between the first optical axis OA1 and the second optical axis OA2 is 60°; the angle between the third optical axis OA3 and the fourth optical axis OA4 is the same as the angle between the first optical axis OA1 and the second optical axis OA2, also 60°; the angle between the second optical axis OA2 and the third optical axis OA3 is twice the angle between the first optical axis OA1 and the second optical axis OA2, that is, 120°; and the first optical axis OA1 and the fourth optical axis OA4 are parallel. Wherein, LY is 10.735 mm, and LZ is 13.736 mm.

[0138] The relevant parameters of each lens in the optical lens 400 in Example 4 are shown in Table 4-1.

[0139] Table 4-1

[0140]

[0141] The surface parameters of the aspheric lens of the optical lens 400 in Example 4 are shown in Table 4-2.

[0142] Table 4-2

[0143]

[0144] In this embodiment, the distortion curve, astigmatism curve, magnification chromatic aberration curve, and axial aberration curve of the optical lens 400 are respectively as follows: Figure 17 、 Figure 18 、 Figure 19 、 Figure 20 shown.

[0145] from Figure 17It can be seen that the distortion of the optical lens is controlled within 0~1%, indicating that the optical lens 400 can correct the distortion well.

[0146] from Figure 18 It can be seen from the figure that the astigmatism of the meridional image plane and the sagittal image plane is controlled within a range of -0.05mm to 0, indicating that the optical lens 400 can correct the astigmatism well.

[0147] from Figure 19 As can be seen from the figure, the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1.5 μm, indicating that the optical lens 400 can correct chromatic aberration very well.

[0148] from Figure 20 It can be seen from the figure that the offset of the axial aberration is controlled within ±0.04 mm, indicating that the optical lens 400 can correct the axial aberration well.

[0149] Please refer to Table 5, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the distance TTL from the object side surface of the first lens to the imaging plane along the first optical axis, the second optical axis, the third optical axis, and the fourth optical axis, the distance TL from the object side surface of the first lens to the light incident surface of the refracting element on the first optical axis, the aperture value Fno, the real image height IH corresponding to the maximum field of view of the optical lens, the maximum field of view FOV of the optical lens, the entrance pupil diameter of the light lens, the back focal length BFL of the optical lens, the principal ray incident angle CRA at the maximum image height, the angle θ between the first optical axis and the second optical axis, the distance LY perpendicular to the first optical axis between the intersection point of the object side surface of the first lens on the first optical axis and the intersection point of the imaging plane on the fourth optical axis, the maximum displacement LZ of the light path from the object side surface of the first lens to the imaging plane parallel to the first optical axis, the thickness LG of the refracting element equivalent to flat glass, and the numerical value corresponding to each conditional expression in each embodiment.

[0150] Table 5

[0151]

[0152] In summary, the optical lens provided by the present invention, through the arrangement of four conventional lenses and one catadioptric element, can achieve excellent periscope-style telephoto photography, offering one or more advantages such as a large image plane, a large aperture, and high-quality imaging, significantly enhancing the user experience. Furthermore, because the optical path undergoes three deflections within the catadioptric element, the volume of the folded optical system is greatly compressed. While achieving excellent telephoto photography, the overall length of the optical lens is significantly reduced, effectively achieving miniaturization.

[0153] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0154] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An optical lens, characterized in that: It consists of four lenses and one catadioptric element, and successively includes from the object side to the imaging surface along the light transmission direction: The first lens with positive optical power, whose object side is convex and whose image side is concave; The second lens with optical power, whose object side is convex and whose image side is concave; The third lens with positive optical power; The fourth lens with optical power, whose object side is convex and whose image side is concave; The catadioptric element includes a light incident surface, a first reflection surface, a second reflection surface, a third reflection surface and a light exit surface that are all planes. Among them, the light incident surface, the second reflection surface and the light exit surface are substantially the same plane; The optical axis of the optical lens includes a first optical axis, a second optical axis, a third optical axis and a fourth optical axis. The light path passes through the first lens, the second lens, the third lens, and the fourth lens along the first optical axis and enters the catadioptric element, passes through the light incident surface to the first reflection surface, is reflected to the second reflection surface, is totally reflected to the third reflection surface, and is then reflected to the light exit surface and exits to the imaging surface; the first reflection surface turns the light path from the first optical axis to the second optical axis, the second reflection surface turns the light path from the second optical axis to the third optical axis, and the third reflection surface turns the light path from the third optical axis to the fourth optical axis; the fourth optical axis is perpendicular to the imaging surface; the first optical axis and the fourth optical axis are parallel; Among them, the true image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens satisfy: 4.5 < ((43.26 / IH) × f) / 23 < 5.

5.

2. The optical lens according to claim 1, wherein: The distance LY perpendicular to the first optical axis between the intersection point of the object side of the first lens on the first optical axis and the intersection point of the imaging surface on the fourth optical axis and the maximum displacement LZ parallel to the first optical axis of the light path from the object side of the first lens to the imaging surface satisfy: 0.7 < LY / LZ < 0.

9.

3. The optical lens according to claim 1, wherein: The distance LY perpendicular to the first optical axis between the intersection point of the object side of the first lens on the first optical axis and the intersection point of the imaging surface on the fourth optical axis and the distance TTL passed along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis from the object side of the first lens to the imaging surface satisfy: 0.32 < LY / TTL < 0.4; the maximum displacement LZ parallel to the first optical axis of the light path from the object side of the first lens to the imaging surface and the distance TTL passed along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis from the object side of the first lens to the imaging surface satisfy: 0.42 < LZ / TTL < 0.

47.

4. The optical lens according to claim 1, wherein: The included angle θ between the first optical axis and the second optical axis satisfies: 54° < θ < 64°.

5. The optical lens according to claim 1, wherein: The effective aperture DM11 of the first lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 0.95 < DM11 / IH < 1.

1.

6. The optical lens according to claim 1, wherein: The focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 0.45 < f1 / f < 2.7; the edge thickness ET1 of the first lens and the central thickness CT1 of the first lens satisfy: 0.32 < ET1 / CT1 < 0.

62.

7. The optical lens according to claim 1, wherein: The focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.4 < f3 / f < 2.

8.

8. The optical lens according to claim 1, wherein: The focal length f1 of the first lens and the focal length f3 of the third lens satisfy: 0.5 < f1 / f3 < 3.

5.

9. The optical lens according to claim 1, wherein: The distance TL on the first optical axis from the object side surface of the first lens to the light incident surface of the refractive element and the thickness LG of the refractive element equivalent to a flat glass satisfy: 0.3 < TL / LG < 0.

5.

10. The optical lens according to claim 1, wherein: The true image height IH corresponding to the maximum field angle of the optical lens and the F-number Fno of the optical lens satisfy: 3.3 mm < IH / Fno < 4.1 mm.

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