Eyepiece optical system

Abstract

The invention discloses an eyepiece optical system, and the system sequentially comprises a first lens with positive focal power from an object side to an image side along an optical axis, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a convex surface or a concave surface; 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; the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface or a convex surface; the total number of the lenses is three. Wherein the curvature radius value R21 of the object side surface of the second lens and the curvature radius value R22 of the image side surface of the second lens meet the condition that (R21 + R22) / (R21-R22) is greater than or equal to-3.193 and less than or equal to-2.116; the curvature radius value R31 of the object side face of the third lens and the curvature radius value R32 of the image side face of the third lens meet the condition that (R31 + R32) / (R31-R32) is larger than or equal to-2.910 and smaller than or equal to-0.514.

Description

Technical Field

[0001] This application relates to the field of optical devices, and particularly to an eyepiece optical system. Background Art

[0002] As a handheld product, the observation and aiming eyepiece pays more attention to portability, requiring the lens to be light in weight and small in size. Therefore, the requirement of miniaturization is put forward. Moreover, the usage scenario of the observation and aiming eyepiece is to observe the details of objects, which requires a large magnification. Therefore, the lens needs to have a small focal length. However, the image of a large magnification lens is relatively dark. To improve the image clarity, a large exit pupil diameter is required. To meet the discrimination of minute details, the observation and aiming eyepiece is required to have a high image quality. At the same time, for accurate measurement and to improve the comfort of human eye observation, the observation and aiming eyepiece is required to have low distortion. To enhance the adaptability of the eyepiece to different interfaces and improve the cost performance, the observation and aiming eyepiece is required to have a long back focal length. And to meet the needs of myopic and hyperopic people to use directly with naked eyes and improve the user experience, the observation and aiming eyepiece needs to be able to achieve a wide range of diopter adjustment. However, the existing observation and aiming eyepieces have the following technical problems:

[0003] 1. It is difficult for the prior art to achieve light weight and miniaturization;

[0004] 2. It is difficult for the prior art to balance a large magnification and low distortion;

[0005] 3. It is difficult for the prior art to balance a long back focal length and a wide range of diopter adjustment;

[0006] 4. It is difficult for the prior art to balance a large exit pupil diameter and a high image quality;

[0007] Therefore, in view of the current development status of the observation and aiming eyepiece, an eyepiece optical system with a short overall length, small size, long exit pupil, high resolution, low distortion, long back focal length and wide diopter range is one of the current market demands. Summary of the Invention

[0008] This application provides an eyepiece optical system, which sequentially includes, from the object side to the image side along the optical axis: a first lens with positive optical power, whose object side is convex and image side is convex or concave; a second lens with negative optical power, whose object side is concave and image side is convex; a third lens with positive optical power, whose object side is convex and image side is concave or convex; a total of 3 lenses. Among them, the curvature radius value R21 of the object side of the second lens and the curvature radius value R22 of the image side of the second lens satisfy: -3.193 ≤ (R21 + R22) / (R21 - R22) ≤ -2.116; the curvature radius value R31 of the object side of the third lens and the curvature radius value R32 of the image side of the third lens satisfy: -2.910 ≤ (R31 + R32) / (R31 - R32) ≤ -0.514.

[0009] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies at least one of the following conditional expressions: 0.734 ≤ F1 / F ≤ 1.653; -2.621 ≤ (R11 + R12) / (R11 - R12) ≤ 0.047; where F1 is the focal length value of the first lens, F is the focal length value of the eyepiece optical system, R11 is the curvature radius value of the object side surface of the first lens, and R12 is the curvature radius value of the image side surface of the first lens.

[0010] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies at least one of the following conditional expressions: -0.875 ≤ F2 / F ≤ -0.474; 0.477 ≤ F3 / F ≤ 1.046; -2.689 ≤ F1 / F2 ≤ -0.923; -1.276 ≤ F2 / F3 ≤ -0.752; where F1 is the focal length value of the first lens, F2 is the focal length value of the second lens, F3 is the focal length value of the third lens, and F is the focal length value of the eyepiece optical system.

[0011] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies at least one of the following conditional expressions: 1.399 ≤ TTL / F ≤ 2.004; 0.424 ≤ BFL / F ≤ 0.591; 0.256 ≤ BFL / TTL ≤ 0.362; where TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system, BFL is the distance from the center of the image side surface of the third lens to the center of the imaging surface of the eyepiece optical system, and F is the focal length value of the eyepiece optical system.

[0012] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies at least one of the following conditional expressions: 1.588 ≤ T1 / CT12 ≤ 3.657; 6.588 ≤ T2 / CT23 ≤ 13.353; 13.619 ≤ T3 / CT23 ≤ 31.939; where T1 is the center thickness of the first lens, T2 is the center thickness of the second lens, T3 is the center thickness of the third lens, CT12 is the center distance from the image side surface of the first lens to the object side surface of the second lens, and CT23 is the center distance from the image side surface of the second lens to the object side surface of the third lens.

[0013] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies at least one of the following conditional expressions: -1.199 ≤ R11 / R12 ≤ 0.450; 0.363 ≤ R21 / R22 ≤ 0.536; -0.300 ≤ R31 / R32 ≤ 0.497; where R11 is the curvature radius value of the object side surface of the first lens, R12 is the curvature radius value of the image side surface of the first lens, R21 is the curvature radius value of the object side surface of the second lens, R22 is the curvature radius value of the image side surface of the second lens, R31 is the curvature radius value of the object side surface of the third lens, and R32 is the curvature radius value of the image side surface of the third lens.

[0014] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies the following conditional formula: -1.342 ≤ R22 / R31 ≤ -0.857; where R22 is the curvature radius value of the image side surface of the second lens, and R31 is the curvature radius value of the object side surface of the third lens.

[0015] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies at least one of the following conditional formulas: 0.284 ≤ ENPD / TTL ≤ 0.408; 0.392 ≤ IH / TTL ≤ 0.561; where ENPD is the exit pupil diameter of the eyepiece optical system, IH is the total image height of the eyepiece optical system, and TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system.

[0016] According to an exemplary embodiment of the present application, the eyepiece optical system satisfies at least one of the following conditional expressions: 0.815 ≤ F1 / F ≤ 1.503; -0.795 ≤ F2 / F ≤ -0.527; 0.530 ≤ F3 / F ≤ 0.951; -2.444 ≤ F1 / F2 ≤ -1.025; -1.160 ≤ F2 / F3 ≤ -0.836; 1.554 ≤ TTL / F ≤ 1.822; 0.316 ≤ ENPD / TTL ≤ 0.371; 0.435 ≤ IH / TTL ≤ 0.510; 0.471 ≤ BFL / F ≤ 0.537; 0.284 ≤ BFL / TTL ≤ 0.329; 1.765 ≤ T1 / CT12 ≤ 3.324; 7.320 ≤ T2 / CT23 ≤ 12.139; 15.132 ≤ T3 / CT23 ≤ 29.035; -1.09 ≤ R11 / R12 ≤ 0.409; 0.403 ≤ R21 / R22 ≤ 0.488; -0.273 ≤ R31 / R32 ≤ 0.451; -1.220 ≤ R22 / R31 ≤ -0.952; -2.383 ≤ (R11 + R12) / (R11 - R12) ≤ 0.043; -2.903 ≤ (R21 + R22) / (R21 - R22) ≤ -2.351; -2.645 ≤ (R31 + R32) / (R31 - R32) ≤ -0.571; where F1 is the focal length value of the first lens, F2 is the focal length value of the second lens, F3 is the focal length value of the third lens, F is the focal length value of the eyepiece optical system, TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system, ENPD is the exit pupil diameter of the eyepiece optical system, IH is the full image height of the eyepiece optical system, BFL is the distance from the center of the image side surface of the third lens to the center of the imaging surface of the eyepiece optical system, T1 is the central thickness of the first lens, T2 is the central thickness of the second lens, T3 is the central thickness of the third lens, CT12 is the central distance from the image side surface of the first lens to the object side surface of the second lens, CT23 is the central distance from the image side surface of the second lens to the object side surface of the third lens. R11 is the curvature radius value of the object side surface of the first lens, R12 is the curvature radius value of the image side surface of the first lens, R21 is the curvature radius value of the object side surface of the second lens, R22 is the curvature radius value of the image side surface of the second lens, R31 is the curvature radius value of the object side surface of the third lens, and R32 is the curvature radius value of the image side surface of the third lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects, and advantages of the present application will become more apparent by reading the following detailed description of non - restrictive embodiments with reference to the accompanying drawings. In the drawings:

[0018] Figure 1 shows a schematic structural diagram of the eyepiece optical system according to Embodiment 1 of the present application;

[0019] Figure 2 Shows a schematic structural diagram of an eyepiece optical system according to Embodiment 2 of the present application;

[0020] Figure 3 Shows a schematic structural diagram of an eyepiece optical system according to Embodiment 3 of the present application;

[0021] Figure 4 Shows a schematic structural diagram of an eyepiece optical system according to Embodiment 4 of the present application;

[0022] Figure 5 Shows a schematic structural diagram of an eyepiece optical system according to Embodiment 5 of the present application;

[0023] Figure 6 Shows a schematic structural diagram of an eyepiece optical system according to Embodiment 6 of the present application;

[0024] Figure 7 Shows a schematic structural diagram of an eyepiece optical system according to Embodiment 7 of the present application; Detailed implementation manners

[0025] To better understand the present application, various aspects of the present application are described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application and do not limit the scope of the present application in any way.

[0026] In the accompanying drawings, for the sake of convenience of illustration, the thickness, size, and shape of the lenses have been slightly exaggerated. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0027] In this document, 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 object to be photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0028] It should also be understood that the terms "comprise", "comprising", "have", "include", and / or "including", when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. 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. It should be noted that the longitudinal direction described herein is the direction perpendicular to the optical axis.

[0029] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms shall be interpreted to have a meaning consistent with their meaning in the context of the relevant art, and shall not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0030] 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 describe this application in detail with reference to the drawings and in combination with the embodiments.

[0031] The features, principles, and other aspects of this application will be described in detail below.

[0032] According to an exemplary embodiment of the present application, the eyepiece optical system may include three lenses with optical powers, namely a first lens, a second lens, and a third lens. These three lenses are arranged in sequence along the optical axis from the object side to the image side. There may be a spacing distance between any two adjacent lenses among the first lens to the third lens.

[0033] In an exemplary embodiment, the eyepiece optical system may further include a photosensitive element disposed on the image side of the third lens. Optionally, the photosensitive element disposed on the image side of the third lens may be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor element (CMOS).

[0034] In an exemplary embodiment, a diaphragm for restricting the light beam may be disposed on the object side of the first lens to further improve the imaging quality of the eyepiece optical system. The diaphragm is beneficial for converging the light entering the eyepiece optical system, reducing the front aperture of the eyepiece optical system, and reducing the assembly sensitivity of the system. However, it should be noted that the position of the diaphragm disclosed herein is only an example and not a limitation; in alternative embodiments, the diaphragm may also be disposed at other positions according to actual needs.

[0035] In an exemplary embodiment, the first lens may have a positive optical power, its object side surface may be convex, and its image side surface may be convex. The first lens having a positive optical power undertakes the main optical power of the system. By collecting light, the light rays emitted from the first lens approach the optical axis direction, reducing the aperture of the rear lens, which is beneficial for miniaturization; the object side surface is convex and the image side surface is convex, which is beneficial for sharing the optical power jointly, reducing the surface curvature, and reducing the generation of aberrations, which is beneficial for achieving high image quality.

[0036] In an exemplary embodiment, the first lens may have a positive optical power. Its object side may be convex, and its image side may be concave. The first lens having a positive optical power bears the main optical power of the system. By collecting light, the light rays emerging from the first lens are made to approach the optical axis, reducing the aperture of the rear lens, which is conducive to miniaturization. The convex object side can collect marginal light rays at a gentler angle, reducing aberrations (such as coma and astigmatism) caused by too large an incident angle of light rays, reducing the difficulty of correcting off-axis aberrations in the system, and facilitating an increase in the field of view. The concave image side causes the light rays to bend towards the image plane along the trend of the light rays, which is conducive to reducing the incident angle of on-axis light rays and reducing the generation of spherical aberration, and is conducive to reducing the tolerance sensitivity.

[0037] In an exemplary embodiment, the second lens may have a negative optical power. Its object side may be concave, and its image side may be convex. The second lens having a negative optical power is the only negative lens in the entire optical system, which is conducive to correcting chromatic aberration and improving imaging quality. The concave object side and the convex image side, and the overall shape is in a "V-shaped" or "M-shaped" facing away from the image plane, which is conducive to balancing the off-axis aberrations of positive and negative diopters, and thus achieving a high image quality in the diopter range of -5D to +5D. When the shape is "M-shaped", the lens shape is more concentrated and the sagitta is smaller, which is conducive to reducing the internal stress during injection molding and ensuring the stability of the surface shape. When the shape is "V-shaped", the lens shape is smoother, the slope change is smaller, and there is no edge reverse curvature, which is conducive to reducing the tolerance sensitivity.

[0038] In an exemplary embodiment, the third lens may have a positive optical power. Its object side may be convex, and its image side may be concave. The third lens having a positive optical power, with a convex object side, bends towards the image plane along the trend of the light rays, which is conducive to reducing the incident angle of on-axis light rays and reducing the generation of spherical aberration, and at the same time is conducive to reducing the tolerance sensitivity. The concave image side makes the shape "meniscus-shaped", which is conducive to correcting the remaining off-axis aberrations of the second lens and achieving a high image quality in the diopter range of -5D to +5D.

[0039] In an exemplary embodiment, the third lens may have a positive optical power. Its object side may be convex, and its image side may be convex. The third lens having a positive optical power, with a convex object side and a convex image side, jointly share the optical power, reducing the surface curvature, which is conducive to reducing the generation of aberrations and achieving high image quality. And the edge aperture of the third lens bends away from the image plane, which is conducive to correcting distortion and reducing the difficulty of correcting other aberrations, and is conducive to achieving low distortion while achieving high image quality.

[0040] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 0.734 ≤ F1 / F ≤ 1.653, where F1 is the focal length value of the first lens and F is the focal length value of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula, the ratio range of the focal length value of the first lens to the focal length value of the eyepiece optical system is controlled, and the optical power of the first lens is reasonably distributed. By collecting light, the light emitted from the first lens approaches the optical axis direction, reducing the aperture of the rear lens, which is beneficial to achieving miniaturization. Preferably, the eyepiece optical system can further satisfy: 0.815 ≤ F1 / F ≤ 1.503.

[0041] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: -0.875 ≤ F2 / F ≤ -0.474, where F2 is the focal length value of the second lens and F is the focal length value of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula, the ratio range of the focal length value of the second lens to the focal length value of the eyepiece optical system is controlled, and the focal length value of the second lens is reasonably distributed, which is beneficial to correcting the chromatic aberration of the system and achieving high image quality. Preferably, the eyepiece optical system can further satisfy: -0.795 ≤ F2 / F ≤ -0.527.

[0042] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 0.477 ≤ F3 / F ≤ 1.046, where F3 is the focal length value of the third lens and F is the focal length value of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula, the ratio range of the focal length value of the third lens to the focal length value of the eyepiece optical system is controlled, which is beneficial to correcting the residual chromatic aberration of the system and achieving high resolution. Preferably, the eyepiece optical system can further satisfy: 0.530 ≤ F3 / F ≤ 0.951.

[0043] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: -2.689 ≤ F1 / F2 ≤ -0.923, where F1 is the focal length value of the first lens and F2 is the focal length value of the second lens. By making the eyepiece optical system satisfy the above conditional formula, the ratio range of the focal length value of the first lens to the focal length value of the second lens is controlled, which is beneficial to the first lens and the second lens balancing the chromatic aberration with each other and achieving high resolution. Preferably, the eyepiece optical system can further satisfy: -2.444 ≤ F1 / F2 ≤ -1.025.

[0044] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: -1.276 ≤ F2 / F3 ≤ -0.752, where F2 is the focal length value of the second lens and F3 is the focal length value of the third lens. By making the eyepiece optical system satisfy the above conditional formula and controlling the ratio range of the focal length value of the second lens and the focal length value of the third lens, it is beneficial for the second lens and the third lens to balance off-axis aberrations with each other, and it is beneficial to achieve a high image quality within a diopter range of -5D to +5D. Preferably, the eyepiece optical system can further satisfy: -1.160 ≤ F2 / F3 ≤ -0.836.

[0045] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 1.399 ≤ TTL / F ≤ 2.004, where TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system, and F is the focal length value of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula and controlling the ratio range of the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system and the focal length value of the eyepiece optical system, when the focal length value of the system is fixed, by controlling the overall optical length of the system, the overall optical length of the system is made smaller, which is beneficial for achieving miniaturization. Preferably, the eyepiece optical system can further satisfy: 1.554 ≤ TTL / F ≤ 1.822.

[0046] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 0.424 ≤ BFL / F ≤ 0.591, where BFL is the distance from the center of the image side surface of the third lens to the center of the imaging surface of the eyepiece optical system, and F is the focal length value of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula and controlling the ratio range of the distance from the center of the image side surface of the third lens to the center of the imaging surface of the eyepiece optical system and the focal length value of the eyepiece optical system, the optical back focal length of the system is controlled, and the adaptability of the eyepiece to different interfaces is enhanced, which is beneficial for improving the cost performance. Preferably, the eyepiece optical system can further satisfy: 0.471 ≤ BFL / F ≤ 0.537.

[0047] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 0.256 ≤ BFL / TTL ≤ 0.362, where TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system, and BFL is the distance from the center of the image side surface of the third lens to the center of the imaging surface of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula and controlling the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system and the distance from the center of the image side surface of the third lens to the center of the imaging surface of the eyepiece optical system, it is beneficial to effectively control the overall optical length while increasing the optical back focal length of the optical system, which is beneficial for achieving the miniaturization of the system. Preferably, the eyepiece optical system can further satisfy: 0.284 ≤ BFL / TTL ≤ 0.329.

[0048] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 0.284 ≤ ENPD / TTL ≤ 0.408, where ENPD is the exit pupil diameter of the system, and TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula, controlling the ratio range of the exit pupil diameter of the system and the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system is beneficial to achieving a larger exit pupil diameter, enabling the light entering the human eye to have a higher ability, and is beneficial to improving the picture clarity. Preferably, the eyepiece optical system can further satisfy: 0.316 ≤ ENPD / TTL ≤ 0.371.

[0049] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 0.392 ≤ IH / TTL ≤ 0.561, where TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system, and IH is the full image height of the eyepiece optical system. By making the eyepiece optical system satisfy the above conditional formula, controlling the ratio range of the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system and the full image height of the eyepiece optical system is beneficial to making the system have a higher magnification and is beneficial to observing object details. Preferably, the eyepiece optical system can further satisfy: 0.435 ≤ IH / TTL ≤ 0.510.

[0050] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 1.588 ≤ T1 / CT12 ≤ 3.657, where T1 is the central thickness of the first lens, and CT12 is the central distance from the image side surface of the first lens to the object side surface of the second lens. By making the eyepiece optical system satisfy the above conditional formula, controlling the ratio range of the central thickness of the first lens and the central distance from the image side surface of the first lens to the object side surface of the second lens is beneficial to improving the assembly manufacturability of the lens. Preferably, the eyepiece optical system can further satisfy: 1.765 ≤ T1 / CT12 ≤ 3.324.

[0051] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 6.588 ≤ T2 / CT23 ≤ 13.353, where T2 is the central thickness of the second lens, and CT23 is the central distance from the image side surface of the second lens to the object side surface of the third lens. By making the eyepiece optical system satisfy the above conditional formula, controlling the ratio range of the central thickness of the second lens and the central distance from the image side surface of the second lens to the object side surface of the third lens is beneficial to improving the assembly manufacturability of the lens. Preferably, the eyepiece optical system can further satisfy: 7.320 ≤ T2 / CT23 ≤ 12.139.

[0052] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 13.619 ≤ T3 / CT23 ≤ 31.939, where T3 is the central thickness of the third lens, and CT23 is the central distance from the image side surface of the second lens to the object side surface of the third lens. By making the eyepiece optical system satisfy the above conditional expression and controlling the ratio range of the central thickness of the third lens and the central distance from the image side surface of the second lens to the object side surface of the third lens, it is beneficial to improve the assembly manufacturability of the lens. Preferably, the eyepiece optical system can further satisfy: 15.132 ≤ T3 / CT23 ≤ 29.035.

[0053] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: -1.199 ≤ R11 / R12 ≤ 0.450, where R11 is the curvature radius value of the object side surface of the first lens, and R12 is the curvature radius value of the image side surface of the first lens. By making the eyepiece optical system satisfy the above conditional expression and controlling the curvature radius value of the object side surface of the first lens and the curvature radius value of the image side surface of the first lens, it is beneficial to balance aberrations and achieve high resolution. Preferably, the eyepiece optical system can further satisfy: -1.09 ≤ R11 / R12 ≤ 0.409.

[0054] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: 0.363 ≤ R21 / R22 ≤ 0.536, where R21 is the curvature radius value of the object side surface of the second lens, and R22 is the curvature radius value of the image side surface of the second lens. By making the eyepiece optical system satisfy the above conditional expression and controlling the curvature radius value of the object side surface of the second lens and the curvature radius value of the image side surface of the second lens, it is beneficial to balance aberrations and achieve high resolution. Preferably, the eyepiece optical system can further satisfy: 0.403 ≤ R21 / R22 ≤ 0.488.

[0055] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: -0.300 ≤ R31 / R32 ≤ 0.497, where R31 is the curvature radius value of the object side surface of the third lens, and R32 is the curvature radius value of the image side surface of the third lens. By making the eyepiece optical system satisfy the above conditional expression and controlling the curvature radius value of the object side surface of the third lens and the curvature radius value of the image side surface of the third lens, it is beneficial to balance aberrations and achieve high resolution. Preferably, the eyepiece optical system can further satisfy: -0.273 ≤ R31 / R32 ≤ 0.451.

[0056] In an exemplary embodiment, the eyepiece optical system according to the present application may satisfy: -1.342 ≤ R22 / R31 ≤ -0.857, where R22 is the curvature radius value of the image side surface of the second lens, and R31 is the curvature radius value of the object side surface of the third lens. By making the eyepiece optical system satisfy the above conditional formula, controlling the curvature radius value of the image side surface of the second lens and the curvature radius value of the object side surface of the third lens is conducive to balancing the off-axis aberrations of positive and negative diopters and achieving high image quality within a diopter range of -5D to +5D. Preferably, the eyepiece optical system may further satisfy: -1.220 ≤ R22 / R31 ≤ -0.952.

[0057] In an exemplary embodiment, the eyepiece optical system according to the present application may satisfy: -2.621 ≤ (R11 + R12) / (R11 - R12) ≤ 0.047, where R11 is the curvature radius value of the object side surface of the first lens, and R12 is the curvature radius value of the image side surface of the first lens. By making the eyepiece optical system satisfy the above conditional formula, controlling the ratio range of the sum of the curvature radius value of the object side surface and the curvature radius value of the image side surface of the first lens to the difference between the curvature radius value of the object side surface and the curvature radius value of the image side surface of the first lens is conducive to balancing aberrations and achieving high resolution. Preferably, the eyepiece optical system may further satisfy: -2.383 ≤ (R11 + R12) / (R11 - R12) ≤ 0.043.

[0058] In an exemplary embodiment, the eyepiece optical system according to the present application may satisfy: -3.193 ≤ (R21 + R22) / (R21 - R22) ≤ -2.116, where R21 is the curvature radius value of the object side surface of the second lens, and R22 is the curvature radius value of the image side surface of the second lens. By making the eyepiece optical system satisfy the above conditional formula, controlling the ratio range of the sum of the curvature radius value of the object side surface and the curvature radius value of the image side surface of the second lens to the difference between the curvature radius value of the object side surface and the curvature radius value of the image side surface of the second lens is conducive to balancing aberrations and achieving high resolution. Preferably, the eyepiece optical system may further satisfy: -2.903 ≤ (R21 + R22) / (R21 - R22) ≤ -2.351.

[0059] In an exemplary embodiment, the eyepiece optical system according to the present application can satisfy: -2.910 ≤ (R31 + R32) / (R31 - R32) ≤ -0.514, where R31 is the curvature radius value of the object side surface of the third lens, and R32 is the curvature radius value of the image side surface of the third lens. By making the eyepiece optical system satisfy the above conditional formula, controlling the ratio range of the sum of the curvature radius value of the object side surface and the curvature radius value of the image side surface of the third lens and the difference between the curvature radius value of the object side surface and the curvature radius value of the image side surface of the third lens is beneficial to balancing aberrations and achieving high resolution. Preferably, the eyepiece optical system can further satisfy: -2.645 ≤ (R31 + R32) / (R31 - R32) ≤ -0.571.

[0060] In an exemplary embodiment, the exit pupil distance of the eyepiece optical system of the present application is 15 mm.

[0061] In an exemplary embodiment, the exit pupil diameter of the eyepiece optical system of the present application is 8 mm.

[0062] In an exemplary embodiment, the magnification of the eyepiece optical system of the present application is 18X.

[0063] In an exemplary embodiment, the distance BFL from the center of the image side surface of the third lens of the eyepiece optical system of the present application to the center of the imaging surface of the eyepiece optical system satisfies: BFL ≥ 6.5 mm. Preferably, it can further satisfy: 6.541 mm ≤ BFL ≤ 7.462 mm.

[0064] In an exemplary embodiment, the diopter range of the eyepiece optical system of the present application is -5D to +5D.

[0065] MTF (i.e., Modulation Transfer Function), which is the modulation transfer function in Chinese, is a quantitative evaluation index for the optical performance of a lens, used to describe the contrast of light transmitted at different spatial frequencies, and its unit is line pairs per millimeter (lp / mm). In an exemplary embodiment, when the diopter of the eyepiece optical system of the present application is 0D, the MTF value of its central field of view > 0.72 @ 30 lp / mm.

[0066] In an exemplary embodiment, the distortion value DIS of the eyepiece optical system of the present application ≤ 4.5%.

[0067] In an exemplary embodiment, as needed, the eyepiece optical system of the present application may further include a protective glass disposed between the last lens and the imaging surface. The protective glass CG can be used to protect the image sensing chip located at the imaging surface and prevent damage to the image-side elements (such as the chip) of the eyepiece optical system.

[0068] In an exemplary embodiment, each lens of the eyepiece optical system can be a spherical lens or an aspherical lens. The present application does not specifically limit the specific number of spherical lenses and aspherical lenses. When focusing on imaging quality, the number of aspherical lenses can be increased, and even all lenses can be aspherical lenses. The characteristic of an aspherical lens is that the curvature continuously changes from the center to the periphery of the lens. Different from a spherical lens with a constant curvature from the center to the periphery, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberration that appears during imaging as much as possible, thereby improving the imaging quality of the lens. Optionally, in the eyepiece optical system according to the present application, the object side and the image side of the first lens, the second lens, and the third lens are all aspherical surfaces.

[0069] The eyepiece optical system according to the above embodiment of the present application sequentially includes a first lens with a positive optical power, a second lens with a negative optical power, and a third lens with a positive optical power along the optical axis from the object side to the image side. By reasonably distributing the optical power, surface type, and the range of each parameter of each lens, the eyepiece optical system of the present application has at least one of the beneficial effects such as a short total length, a small volume, a long exit pupil, high resolution, low distortion, a long back focal length, and a wide field of view (-5D to +5D).

[0070] However, those skilled in the art should understand that without departing from the technical solution claimed in the present application, the number of lenses constituting the eyepiece optical system can be changed to obtain the various results and advantages described in this specification.

[0071] The following further describes specific embodiments of the eyepiece optical system applicable to the above embodiments with reference to the accompanying drawings.

[0072] Embodiment 1

[0073] The following refers to Figure 1 Describe the eyepiece optical system according to Embodiment 1 of the present application. Figure 1 A schematic structural diagram of the eyepiece optical system according to Embodiment 1 of the present application is shown.

[0074] As Figure 1 shown, the eyepiece optical system sequentially includes: a first lens L1, a second lens L2, and a third lens L3 along the optical axis from the object side to the image side.

[0075] The first lens L1 has a positive optical power, its object side S1 is a convex surface, and its image side S2 is a convex surface.

[0076] The second lens L2 has a negative optical power, its object side S3 is a concave surface, and its image side S4 is a convex surface.

[0077] The third lens L3 has a positive optical power, its object side S5 is a convex surface, and its image side S6 is a concave surface.

[0078] The eyepiece optical system further includes a diaphragm STO disposed on the object side of the first lens L1.

[0079] Optionally, the eyepiece optical system further includes a protective glass CG disposed on the image side of the third lens L3, which has an object side surface S7 and an image side surface S8.

[0080] Light from the object sequentially passes through the surfaces S1 - S8 and finally forms an image on the imaging surface IMA. It should be noted that the surfaces S1 to S8 are not shown in Figure 1 it.

[0081] Table 1 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of the eyepiece optical system of Example 1, where the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0082] Table 1

[0083]

[0084] In Example 1, the object side surfaces and image side surfaces of the first lens, the second lens, and the third lens are all aspherical surfaces. The surface profiles of the aspherical lenses can be defined by, but not limited to, the following aspherical formula:

[0085]

[0086] where x is the sagitta, the distance from the vertex of the aspherical surface at the position with a height of h along the optical axis direction; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic constant; Ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 below gives the conic constant k and the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical surfaces S1 to S6 in Example 1.

[0087] Table 2

[0088]

[0089]

[0090] Example 2

[0091] The following refers to Figure 2 to describe the eyepiece optical system according to Embodiment 2 of the present application. Figure 2 Fig. shows a schematic structural diagram of the eyepiece optical system according to Embodiment 2 of the present application.

[0092] As Figure 2As shown, the eyepiece optical system sequentially includes, along the optical axis from the object side to the image side: a first lens L1, a second lens L2, and a third lens L3.

[0093] The first lens L1 has a positive optical power, its object side surface S1 is convex, and its image side surface S2 is convex.

[0094] The second lens L2 has a negative optical power, its object side surface S3 is concave, and its image side surface S4 is convex.

[0095] The third lens L3 has a positive optical power, its object side surface S5 is convex, and its image side surface S6 is concave.

[0096] The eyepiece optical system further includes a stop STO disposed on the object side of the first lens L1.

[0097] Optionally, the eyepiece optical system further includes a protective glass CG disposed on the image side of the third lens L3, which has an object side surface S7 and an image side surface S8.

[0098] Light from the object sequentially passes through the surfaces S1 - S8 and finally forms an image on the imaging surface IMA. It should be noted that the surfaces S1 to S8 are not shown in Figure 2 herein.

[0099] Table 3 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of the eyepiece optical system of Example 2, where the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0100] Table 3

[0101]

[0102] In Example 2, the object side surfaces and image side surfaces of the first lens, the second lens, and the third lens are all aspherical surfaces, and the surface profiles of the aspherical lenses can be defined by, but not limited to, the formula (1) given in the above Example 1.

[0103] The following Table 4 gives the conic coefficients k and the higher - order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical surfaces S1 to S6 in Example 2.

[0104] Table 4

[0105] Plane Number S1 S2 S3 S4 S5 S6 K Value 0.040 -0.632 -2.480 -4.860 -0.684 -15.988 A4 -8.199E-05 3.434E-04 2.619E-04 -3.133E-04 -2.580E-03 3.092E-04 A6 5.144E-06 -1.215E-05 8.023E-06 2.057E-05 5.995E-05 -2.074E-05 A8 -3.352E-07 2.375E-07 -2.888E-08 -3.131E-07 -1.767E-06 -4.305E-07 A10 5.514E-09 -1.997E-09 -2.719E-09 7.554E-09 1.344E-08 1.766E-08 A12 5.983E-12 -1.627E-11 2.889E-11 -1.404E-10 6.715E-11 -1.234E-10 A14 -1.600E-12 1.800E-13 4.082E-14 8.541E-13 7.475E-13 1.330E-13 A16 1.516E-14 4.604E-15 2.308E-15 2.276E-15 -2.833E-14 -1.327E-15 A18 1.226E-17 -1.058E-17 -1.122E-18 -9.874E-18 6.589E-17 -3.176E-16 A20 -2.982E-19 -3.743E-19 -5.132E-19 -3.866E-19 1.537E-19 4.867E-18

[0106] Example 3

[0107] The following refers to Figure 3 to describe the eyepiece optical system according to Embodiment 3 of the present application. Figure 3 FIG. shows a schematic structural diagram of the eyepiece optical system according to Embodiment 3 of the present application.

[0108] As shown Figure 3 in FIG. 1, the eyepiece optical system sequentially includes, along the optical axis from the object side to the image side: a first lens L1, a second lens L2, and a third lens L3.

[0109] The first lens L1 has a positive optical power, its object surface S1 is convex, and its image surface S2 is convex.

[0110] The second lens L2 has a negative optical power, its object surface S3 is concave, and its image surface S4 is convex.

[0111] The third lens L3 has a positive optical power, its object surface S5 is convex, and its image surface S6 is concave.

[0112] The eyepiece optical system further includes a stop STO disposed on the object side of the first lens L1.

[0113] Optionally, the eyepiece optical system further includes a protective glass CG disposed on the image side of the third lens L3, which has an object surface S7 and an image surface S8.

[0114] Light from the object sequentially passes through each surface S1 - S8 and finally forms an image on the imaging surface IMA. It should be noted that the surfaces S1 to S8 are not shown in Figure 3 FIG. 1.

[0115] Table 5 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of the eyepiece optical system of Example 3, where the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0116] Table 5

[0117]

[0118]

[0119] In Example 3, the object surfaces and image surfaces of the first lens, the second lens, and the third lens are all aspherical surfaces, and the surface profiles of the aspherical lenses can be defined by, but not limited to, the formula (1) given in the above Example 1.

[0120] The following Table 6 gives the conic coefficients k and the higher - order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each of the aspherical surfaces S1 to S6 in Example 3.

[0121] Table 6

[0122] Plane Number S1 S2 S3 S4 S5 S6 K Value -0.071 -49.987 -3.478 -8.748 -0.762 -23.158 A4 -3.142E-05 9.294E-04 1.153E-03 2.803E-04 -3.318E-03 8.421E-04 A6 3.072E-06 -3.092E-05 -4.901E-06 2.389E-05 1.135E-04 -2.065E-05 A8 -3.719E-07 2.609E-07 -8.670E-08 -2.557E-07 -2.543E-06 2.267E-08 A10 6.521E-09 1.886E-10 -1.781E-09 7.556E-09 1.201E-08 9.252E-09 A12 7.947E-12 -9.734E-12 4.140E-11 -1.562E-10 2.990E-10 -3.063E-10 A14 -1.882E-12 1.122E-14 1.986E-13 4.323E-13 2.704E-12 4.598E-13 A16 8.092E-15 5.638E-15 6.525E-15 -1.980E-15 -1.205E-13 6.209E-14 A18 3.168E-16 3.855E-18 -8.767E-17 -4.278E-16 -2.332E-15 -5.671E-17 A20 -2.760E-18 -7.402E-19 -8.807E-19 7.648E-18 4.477E-17 -5.639E-18

[0123] Example 4

[0124] The following refers to Figure 4Describe the eyepiece optical system according to Embodiment 4 of the present application. Figure 4 The structural schematic diagram of the eyepiece optical system according to Embodiment 4 of the present application is shown.

[0125] As Figure 4 shown, the eyepiece optical system sequentially includes, along the optical axis from the object side to the image side: a first lens L1, a second lens L2, and a third lens L3.

[0126] The first lens L1 has a positive optical power, its object surface S1 is convex, and its image surface S2 is convex.

[0127] The second lens L2 has a negative optical power, its object surface S3 is concave, and its image surface S4 is convex.

[0128] The third lens L3 has a positive optical power, its object surface S5 is convex, and its image surface S6 is concave.

[0129] The eyepiece optical system further includes a stop STO disposed on the object side of the first lens L1.

[0130] Optionally, the eyepiece optical system further includes a protective glass CG disposed on the image side of the third lens L3, which has an object surface S7 and an image surface S8.

[0131] The light from the object sequentially passes through each surface S1 - S8 and finally forms an image on the imaging surface IMA. It should be noted that the surfaces S1 to S8 are not shown in Figure 4 this figure.

[0132] Table 7 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of the eyepiece optical system of Embodiment 4, where the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0133] Table 7

[0134]

[0135]

[0136] In Embodiment 4, the object surfaces and image surfaces of the first lens, the second lens, and the third lens are all aspherical surfaces, and the surface profiles of the aspherical lenses can be defined by, but not limited to, the formula (1) given in Embodiment 1 above.

[0137] The following Table 8 gives the conic coefficients k and the higher - order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each of the aspherical surfaces S1 to S6 in Embodiment 4.

[0138] Table 8

[0139] Plane Number S1 S2 S3 S4 S5 S6 K Value -0.194 -0.860 -2.599 -5.408 -0.923 -14.667 A4 -2.029E-04 3.152E-04 3.468E-05 -3.800E-04 -2.287E-03 -1.359E-05 A6 8.927E-06 -1.107E-05 7.287E-06 1.923E-05 5.047E-05 -9.844E-06 A8 -3.474E-07 3.192E-07 3.560E-08 -3.515E-07 -1.250E-06 -3.640E-07 A10 5.507E-09 -2.109E-09 -1.862E-09 7.704E-09 1.286E-08 1.758E-08 A12 7.405E-13 -2.678E-11 2.671E-11 -1.331E-10 1.662E-11 -1.722E-10 A14 -1.807E-12 1.757E-13 -8.646E-14 1.111E-12 1.048E-12 6.071E-14 A16 1.087E-14 8.791E-15 4.216E-15 9.793E-15 -2.640E-14 1.785E-14 A18 3.499E-16 1.018E-17 -6.771E-17 -3.661E-16 -1.214E-16 -4.932E-16 A20 -3.442E-18 -1.460E-18 -1.548E-19 2.554E-18 2.663E-18 8.428E-18

[0140] Embodiment 5

[0141] The following is a reference to Figure 5 describe the eyepiece optical system according to Embodiment 5 of the present application. Figure 5 The structural schematic diagram of the eyepiece optical system according to Embodiment 5 of the present application is shown.

[0142] As Figure 5 shown, the eyepiece optical system sequentially includes, along the optical axis from the object side to the image side: a first lens L1, a second lens L2, and a third lens L3.

[0143] The first lens L1 has a positive optical power, its object side surface S1 is a convex surface, and its image side surface S2 is a convex surface.

[0144] The second lens L2 has a negative optical power, its object side surface S3 is a concave surface, and its image side surface S4 is a convex surface.

[0145] The third lens L3 has a positive optical power, its object side surface S5 is a convex surface, and its image side surface S6 is a convex surface.

[0146] The eyepiece optical system further includes a diaphragm STO disposed on the object side of the first lens L1.

[0147] Optionally, the eyepiece optical system further includes a protective glass CG disposed on the image side of the third lens L3, which has an object side surface S7 and an image side surface S8.

[0148] The light from the object sequentially passes through each surface S1 - S8 and finally forms an image on the imaging surface IMA. It should be noted that the surfaces S1 to S8 are not shown in Figure 5 this figure.

[0149] Table 9 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of the eyepiece optical system of Embodiment 5, where the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0150] Table 9

[0151]

[0152] In Embodiment 5, the object side surface and the image side surface of the first lens, the second lens, and the third lens are all aspherical surfaces, and the surface types of the aspherical lenses can be defined by, but are not limited to, the formula (1) given in Embodiment 1 above.

[0153] The following Table 10 gives the conic coefficients k and the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each of the aspherical surfaces S1 to S6 in Embodiment 5.

[0154] Table 10

[0155] Plane Number S1 S2 S3 S4 S5 S6 K Value -0.663 -2.265 -1.942 -5.066 -2.939 -6.734 A4 7.104E-05 -2.117E-04 3.832E-04 3.758E-04 1.008E-04 9.492E-04 A6 -4.287E-06 3.594E-06 -1.177E-05 -2.239E-05 1.625E-05 -1.173E-05 A8 1.015E-07 9.031E-08 1.099E-07 6.487E-07 -6.952E-07 -7.604E-09 A10 -1.452E-09 -8.881E-09 5.572E-09 -1.161E-08 1.645E-08 2.061E-09 A12 2.976E-12 2.340E-10 -1.720E-10 1.488E-10 -2.451E-10 -5.370E-11 A14 1.936E-13 -2.630E-12 1.952E-12 -1.222E-12 1.999E-12 5.828E-13 A16 -2.481E-15 1.105E-14 -7.737E-15 4.493E-15 -7.345E-15 -2.459E-15 A18 -5.595E-18 2.950E-18 2.094E-20 -2.382E-20 -1.482E-18 1.872E-18 A20 6.843E-20 -1.961E-20 -7.297E-21 2.086E-21 -7.584E-21 -1.342E-20

[0156] Example 6

[0157] The following is a reference to Figure 6 describe the eyepiece optical system according to Example 6 of the present application. Figure 6 The structural schematic diagram of the eyepiece optical system according to Example 6 of the present application is shown.

[0158] As Figure 6 shown, the eyepiece optical system sequentially includes, along the optical axis from the object side to the image side: a first lens L1, a second lens L2, and a third lens L3.

[0159] The first lens L1 has a positive optical power, its object side surface S1 is convex, and its image side surface S2 is convex.

[0160] The second lens L2 has a negative optical power, its object side surface S3 is concave, and its image side surface S4 is convex.

[0161] The third lens L3 has a positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex.

[0162] The eyepiece optical system further includes a diaphragm STO disposed on the object side of the first lens L1.

[0163] Optionally, the eyepiece optical system further includes a protective glass CG disposed on the image side of the third lens L3, which has an object side surface S7 and an image side surface S8.

[0164] The light from the object sequentially passes through each surface S1 - S8 and finally forms an image on the imaging surface IMA. It should be noted that the surfaces S1 to S8 are not shown in Figure 6 this figure.

[0165] Table 11 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of the eyepiece optical system of Example 6, where the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0166] Table 11

[0167]

[0168] In Example 6, the object side surface and the image side surface of the first lens, the second lens, and the third lens are all aspherical surfaces. The surface profiles of the aspherical lenses can be defined by, but are not limited to, the formula (1) given in Example 1 above.

[0169] The following Table 12 gives the conic coefficients k and the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each of the aspherical surfaces S1 to S6 in Example 6.

[0170] Table 12

[0171] Plane Number S1 S2 S3 S4 S5 S6 K Value -0.248 -1.068 -1.853 -5.419 -3.624 2.749 A4 1.659E-04 -8.419E-05 4.319E-04 1.817E-04 1.979E-04 1.148E-03 A6 -1.328E-05 5.242E-06 -7.279E-06 -1.964E-05 1.876E-06 -2.356E-05 A8 6.118E-07 8.076E-08 2.912E-08 6.751E-07 -5.069E-07 -1.161E-08 A10 -1.731E-08 -8.647E-09 7.271E-09 -1.166E-08 1.227E-08 4.209E-09 A12 2.629E-10 2.356E-10 -1.934E-10 1.476E-10 -1.877E-10 -3.060E-11 A14 -4.726E-13 -2.621E-12 2.081E-12 -1.194E-12 2.526E-12 3.842E-13 A16 -4.787E-14 1.175E-14 -1.564E-15 4.782E-15 -3.051E-14 -7.638E-15 A18 5.573E-16 1.877E-17 -9.173E-17 -4.404E-18 3.469E-16 1.307E-17 A20 -1.423E-18 -3.580E-19 7.492E-20 -1.290E-19 -2.256E-18 3.136E-19

[0172] Example 7

[0173] The following is a reference to Figure 7 Describe the eyepiece optical system according to Example 7 of the present application. Figure 7 The structural schematic diagram of the eyepiece optical system according to Example 7 of the present application is shown.

[0174] As Figure 7 shown, the eyepiece optical system sequentially includes, from the object side to the image side along the optical axis: a first lens L1, a second lens L2, and a third lens L3.

[0175] The first lens L1 has a positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave.

[0176] The second lens L2 has a negative optical power, its object side surface S3 is concave, and its image side surface S4 is convex.

[0177] The third lens L3 has a positive optical power, its object side surface S5 is convex, and its image side surface S6 is concave.

[0178] The eyepiece optical system further includes a stop STO disposed on the object side of the first lens L1.

[0179] Optionally, the eyepiece optical system further includes a protective glass CG disposed on the image side of the third lens L3, which has an object side surface S7 and an image side surface S8.

[0180] The light from the object sequentially passes through the surfaces S1 - S8 and finally forms an image on the imaging surface IMA. It should be noted that the surfaces S1 to S8 are not shown in Figure 7 this figure.

[0181] Table 13 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of the eyepiece optical system of Example 7, where the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0182] Table 13

[0183]

[0184] In Example 7, the object side surfaces and image side surfaces of the first lens, the second lens, and the third lens are all aspherical surfaces, and the surface profiles of the aspherical lenses can be defined by, but are not limited to, the formula (1) given in the above Example 1.

[0185] The following Table 14 gives the conic coefficients k and the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical surfaces S1 to S6 in Example 7.

[0186] Table 14

[0187]

[0188]

[0189] In summary, the conditions in Examples 1 to 7 satisfy the relationships shown in Table 15. In Table 15, the unit of each parameter is millimeter (mm).

[0190] Table 15

[0191] Conditional Expression / Example 1 2 3 4 5 6 7 F 12.985 12.981 13.105 11.322 13.980 12.667 20.871 TTL 22.641 22.578 21.585 22.826 25.302 24.571 22.697 BEL 6.931 6.731 6.541 6.842 7.205 6.981 7.462 F1 / F 0.935 0.935 0.943 0.815 1.006 0.912 1.503 F2 / F -0.730 -0.752 -0.704 -0.795 -0.527 -0.535 -0.615 F3 / F 0.772 0.784 0.743 0.951 0.585 0.619 0.530 F1 / F2 -1.281 -1.242 -1.341 -1.025 -1.910 -1.703 -2.444 F2 / F3 -0.945 -0.959 -0.948 -0.836 -0.901 -0.864 -1.160 TTL / F 1.630 1.625 1.554 1.643 1.822 1.769 1.634 ENPD / TTL 0.353 0.354 0.371 0.350 0.316 0.326 0.352 IH / TTL 0.486 0.487 0.510 0.482 0.435 0.448 0.485 BFL / F 0.499 0.485 0.471 0.493 0.519 0.503 0.537 BFL / TTL 0.306 0.298 0.303 0.300 0.285 0.284 0.329 T1 / CT12 2.480 2.748 3.324 3.129 1.829 1.932 1.765 T2 / CT23 7.453 7.832 8.293 12.139 7.320 10.565 8.136 T3 / CT23 15.737 15.132 18.818 17.924 22.107 29.035 28.045 R11 / R12 -0.695 -0.555 -0.311 -0.863 -0.978 -1.090 0.409 R21 / R22 0.484 0.488 0.482 0.455 0.417 0.403 0.465 R31 / R32 0.302 0.293 0.376 0.451 -0.162 -0.273 0.051 R22 / R31 -0.998 -0.972 -1.095 -1.073 -0.986 -0.952 -1.220 (R11 + R12) / (R11 - R12) -0.180 -0.286 -0.526 -0.074 -0.011 0.043 -2.383 (R21 + R22) / (R21 - R22) -2.877 -2.903 -2.864 -2.669 -2.429 -2.351 -2.740 (R31 + R32) / (R31 - R32) -1.866 -1.829 -2.206 -2.645 -0.722 -0.571 -1.108

[0192] This application also provides an imaging device, the electronic photosensitive element of which can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor device (CMOS), and the imaging device is equipped with the eyepiece optical system described above.

[0193] The above description is only the preferred embodiments of this application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in this application.

Claims

1. Eyepiece optical system, characterized in that, In order from the object side to the image side along the optical axis, it includes: A first lens with positive optical power, whose object side is convex and whose image side is convex or concave; A second lens with negative optical power, whose object side is concave and whose image side is convex; A third lens with positive optical power, whose object side is convex and whose image side is concave or convex; There are a total of 3 lenses; among them, The curvature radius value R21 of the object side of the second lens and the curvature radius value R22 of the image side of the second lens satisfy: -3.193 ≤ (R21 + R22) / (R21 - R22) ≤ -2.116; The curvature radius value R31 of the object side of the third lens and the curvature radius value R32 of the image side of the third lens satisfy: -2.910 ≤ (R31 + R32) / (R31 - R32) ≤ -0.

514.

2. The eyepiece optical system according to claim 1, wherein The eyepiece optical system satisfies at least one of the following conditional expressions 0.734 ≤ F1 / F ≤ 1.653; -2.621 ≤ (R11 + R12) / (R11 - R12) ≤ 0.047; Wherein, F1 is the focal length value of the first lens, F is the focal length value of the eyepiece optical system, R11 is the curvature radius value of the object side of the first lens, and R12 is the curvature radius value of the image side of the first lens.

3. The eyepiece optical system according to claim 1, characterized in that, The eyepiece optical system satisfies at least one of the following conditional expressions: -0.875 ≤ F2 / F ≤ -0.474; 0.477 ≤ F3 / F ≤ 1.046; -2.689 ≤ F1 / F2 ≤ -0.923; -1.276 ≤ F2 / F3 ≤ -0.752; Wherein, F1 is the focal length value of the first lens, F2 is the focal length value of the second lens, F3 is the focal length value of the third lens, and F is the focal length value of the eyepiece optical system.

4. The eyepiece optical system according to claim 1, wherein The eyepiece optical system satisfies at least one of the following conditional expressions: 1.399 ≤ TTL / F ≤ 2.004; 0.424 ≤ BFL / F ≤ 0.591; 0.256 ≤ BFL / TTL ≤ 0.362; Wherein, TTL is the distance from the center of the object side of the first lens to the center of the imaging surface of the eyepiece optical system, BFL is the distance from the center of the image side of the third lens to the center of the imaging surface of the eyepiece optical system, and F is the focal length value of the eyepiece optical system.

5. The eyepiece optical system according to claim 1, characterized in that The eyepiece optical system satisfies at least one of the following conditional expressions: 1.588 ≤ T1 / CT12 ≤ 3.657; 6.588 ≤ T2 / CT23 ≤ 13.353; 13.619 ≤ T3 / CT23 ≤ 31.939; Wherein, T1 is the center thickness of the first lens, T2 is the center thickness of the second lens, T3 is the center thickness of the third lens, CT12 is the center distance from the image side of the first lens to the object side of the second lens, and CT23 is the center distance from the image side of the second lens to the object side of the third lens.

6. The eyepiece optical system according to claim 1, characterized in that, The eyepiece optical system satisfies at least one of the following conditional expressions: -1.199 ≤ R11 / R12 ≤ 0.450; 0.363 ≤ R21 / R22 ≤ 0.536; -0.300 ≤ R31 / R32 ≤ 0.497; Wherein, R11 is the curvature radius value of the object side surface of the first lens, R12 is the curvature radius value of the image side surface of the first lens, R21 is the curvature radius value of the object side surface of the second lens, R22 is the curvature radius value of the image side surface of the second lens, R31 is the curvature radius value of the object side surface of the third lens, and R32 is the curvature radius value of the image side surface of the third lens.

7. The eyepiece optical system according to claim 1, wherein, The eyepiece optical system satisfies the following conditional expressions: -1.342 ≤ R22 / R31 ≤ -0.857; Wherein, R22 is the curvature radius value of the image side surface of the second lens, and R31 is the curvature radius value of the object side surface of the third lens.

8. The eyepiece optical system according to claim 1, wherein, The eyepiece optical system satisfies at least one of the following conditional expressions: 0.284 ≤ ENPD / TTL ≤ 0.408; 0.392 ≤ IH / TTL ≤ 0.561; Wherein, ENPD is the exit pupil diameter of the eyepiece optical system, IH is the full image height of the eyepiece optical system, and TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system.

9. The eyepiece optical system according to claim 1, characterized in that The eyepiece optical system satisfies at least one of the following conditional expressions: 0.815 ≤ F1 / F ≤ 1.503; -0.795 ≤ F2 / F ≤ -0.527; 0.530 ≤ F3 / F ≤ 0.951; -2.444 ≤ F1 / F2 ≤ -1.025; -1.160 ≤ F2 / F3 ≤ -0.836; 1.554 ≤ TTL / F ≤ 1.822; 0.316 ≤ ENPD / TTL ≤ 0.371; 0.435 ≤ IH / TTL ≤ 0.510; 0.471 ≤ BFL / F ≤ 0.537; 0.284 ≤ BFL / TTL ≤ 0.329; 1.765 ≤ T1 / CT12 ≤ 3.324; 7.320 ≤ T2 / CT23 ≤ 12.139; 15.132 ≤ T3 / CT23 ≤ 29.035; -1.09 ≤ R11 / R12 ≤ 0.409; 0.403 ≤ R21 / R22 ≤ 0.488; -0.273 ≤ R31 / R32 ≤ 0.451; -1.220 ≤ R22 / R31 ≤ -0.952; -2.383 ≤ (R11 + R12) / (R11 - R12) ≤ 0.043; -2.903 ≤ (R21 + R22) / (R21 - R22) ≤ -2.351; -2.645 ≤ (R31 + R32) / (R31 - R32) ≤ -0.571; Among them, F1 is the focal length value of the first lens, F2 is the focal length value of the second lens, F3 is the focal length value of the third lens, F is the focal length value of the eyepiece optical system, TTL is the distance from the center of the object side surface of the first lens to the center of the imaging surface of the eyepiece optical system, ENPD is the exit pupil diameter of the eyepiece optical system, IH is the full holographic height of the eyepiece optical system, BFL is the distance from the center of the image side surface of the third lens to the center of the imaging surface of the eyepiece optical system, T1 is the central thickness of the first lens, T2 is the central thickness of the second lens, T3 is the central thickness of the third lens, CT12 is the central distance from the image side surface of the first lens to the object side surface of the second lens, and CT23 is the central distance from the image side surface of the second lens to the object side surface of the third lens. R11 is the curvature radius value of the object side surface of the first lens, R12 is the curvature radius value of the image side surface of the first lens, R21 is the curvature radius value of the object side surface of the second lens, R22 is the curvature radius value of the image side surface of the second lens, R31 is the curvature radius value of the object side surface of the third lens, and R32 is the curvature radius value of the image side surface of the third lens.

Images