Optical system and optical lens

Abstract

The invention provides an optical system and an optical lens, and belongs to the technical field of photography. The optical system comprises a first lens group, a first reflection structure, a second reflection structure, a second lens group and an image surface which are sequentially arranged from an object side to an image side along an optical axis. The length of the whole optical system is shortened, the structure is more compact, the controllability of the length size of the optical system and the optical performance are both achieved, light rays are diverged through the third lens with the negative focal power, the focal length of the system is further increased, the correction capacity of field curvature is improved, and the imaging quality is improved. Meanwhile, the clear aperture of the through hole is utilized to the maximum extent, telecentric image space is achieved, the relative illumination of a field of view is improved, the imaging signal-to-noise ratio of an edge area is remarkably improved, edge image quality degradation caused by insufficient illumination is avoided, and the lens is particularly suitable for a low-illumination environment and has a wide application prospect. Therefore, on the basis of miniaturization of the optical system, the small focal ratio and the illumination uniformity of the field of view are considered at the same time.

Description

Technical Field

[0001] This invention relates to the field of photography technology, and more specifically, to an optical system and an optical lens. Background Technology

[0002] Optical systems are widely used in consumer electronics, professional photography, security monitoring, industrial automation, and medical equipment. With the continuous expansion of application scenarios and markets, higher demands are being placed on miniaturization, image quality, and focal length. In photography, especially in long-distance shooting scenarios such as wildlife and astrophotography, telephoto lenses have become indispensable tools. However, to achieve long focal lengths, traditional optical designs often face the problem of a significant increase in the physical length of the lens. Existing reflex lenses, through optical path folding structures, can achieve long focal lengths with a "short lens body and light weight," but their focal ratios are large, typically in the range of f / 10 to f / 15. Compared to lenses with smaller focal ratios, if existing reflex lenses and smaller focal ratio lenses are shooting the same target, and if the desired image brightness is to be the same, the existing reflex lens requires a longer exposure time. This is particularly evident in astrophotography, where exposures to the target can last for several hours, and the larger the focal ratio, the longer the exposure time. Therefore, while ensuring a long focal length, miniaturization of the optical system, high imaging quality, and a small focal ratio are technical problems that urgently need to be solved in this field. Summary of the Invention

[0003] To address the aforementioned problems, this application provides an optical system and an optical lens.

[0004] In a first aspect, embodiments of this application provide an optical system comprising a first lens group, a first reflecting structure, a second reflecting structure, a second lens group, and an image plane arranged sequentially along the optical axis from the object side to the image side; the first reflecting structure and the second reflecting structure are both optical structures for reflecting light; the first lens group includes a first lens with negative optical power and a second lens with positive optical power; a through hole is provided through a first predetermined area of ​​the first reflecting structure, and the second lens group is disposed at a position corresponding to the through hole; the second reflecting structure is disposed in the first predetermined area of ​​the image-side mirror of the first lens group; the second lens group includes a third lens with negative optical power, and the third lens is disposed on the object side of the second lens group; the ratio of the distance L1 between the reflecting surface of the second reflecting structure and the object-side mirror of the third lens to the distance L2 between the reflecting surface of the second reflecting structure and the reflecting surface of the first reflecting structure is greater than or equal to 40% and less than or equal to 80%.

[0005] Preferably, the through hole is disposed in the central region of the first reflective structure, and the second reflective structure is disposed in the central region of the most image-side mirror of the first lens group.

[0006] Preferably, the ratio of the distance L1 between the reflecting surface of the second reflecting structure and the object-side mirror surface of the third lens to the distance L2 between the reflecting surface of the second reflecting structure and the reflecting surface of the first reflecting structure is greater than or equal to 50% and not greater than 70%.

[0007] Preferably, the second reflective structure is a reflective film connected to the most image-side mirror surface of the first lens group.

[0008] Preferably, the ratio of the diameter of the second reflective structure to the diameter of the most image-side lens of the first lens group is less than or equal to 50%, and this ratio can be selected as 30%-45%.

[0009] Preferably, the ratio of the diameter of the through hole to the diameter of the first reflective structure is less than or equal to 40%, and this ratio can be selected as 20%-40%.

[0010] Preferably, the absolute value of the ratio of the focal length f3 of the first reflective structure to the focal length f of the optical system is greater than or equal to 0.4 and less than or equal to 0.5.

[0011] Preferably, the first lens and the second lens are arranged sequentially along the optical axis from the object side to the image side.

[0012] Preferably, the object-side mirror surface of the first lens is concave and the image-side mirror surface is convex.

[0013] And / or, the image-side mirror surface of the second lens is convex.

[0014] Preferably, the absolute value of the ratio of the focal length f1 of the first lens to the focal length f2 of the second lens is greater than or equal to 1 and less than or equal to 2.

[0015] Preferably, the focal ratio of the optical system is greater than or equal to 3 and less than or equal to 6.

[0016] Preferably, the ratio of the distance L0 between the object-side mirror and the image plane of the first lens group to the focal length f of the optical system is greater than or equal to 0.2 and less than or equal to 0.5, and the ratio can be selected as greater than or equal to 0.28 and less than or equal to 0.43.

[0017] Preferably, the radius of the RMS spot in the field of view of the optical system does not exceed 1.5 times the radius of the Airy disk, and the radius of the GEO spot does not exceed 3 times the radius of the Airy disk.

[0018] Preferably, the relative illumination of the edge field of view of the optical system is greater than or equal to 90%.

[0019] Preferably, the second lens group further includes a positive optical power correction lens group.

[0020] Secondly, embodiments of this application provide an optical lens, including a lens barrel and an optical system as described in any of the first aspects, wherein the optical system is installed inside the lens barrel.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. The ratio of the distance L1 between the reflecting surface of the second reflecting structure and the object-side mirror of the third lens to the distance L2 between the reflecting surface of the second reflecting structure and the reflecting surface of the first reflecting structure is not less than 40% and not greater than 80%, so that at least a part of the second lens group extends into the space between the first and second reflecting structures, shortening the overall length of the optical system and making the structure more compact. This achieves controllability of the length of the optical system and balances optical performance. The third lens with negative optical power causes light to diverge, thereby further increasing the focal length of the system and improving the field curvature correction capability. At the same time, it maximizes the use of the light-passing aperture of the through hole and achieves image-side telecenty, improving the relative illumination of the field of view. The imaging signal-to-noise ratio of the edge region is significantly improved, avoiding edge image quality degradation caused by insufficient illumination. It is especially suitable for low-light environments. Overall, the optical system balances small focal ratio and field illumination uniformity on the basis of miniaturization.

[0023] 2. The first lens group, consisting of a first lens with negative optical power and a second lens with positive optical power, plays a role in correcting aberrations such as spherical aberration and coma in the optical system, thereby further improving the imaging quality of the optical system. Compared with the large meniscus lens used in related technologies, this application has a larger centering coefficient, is easier to process, and improves production efficiency and yield. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a first structural schematic diagram of an optical system provided in an embodiment of this application;

[0026] Figure 2 This is a second structural schematic diagram of an optical system provided in an embodiment of this application;

[0027] Figure 3 This is a third structural schematic diagram of an optical system provided in an embodiment of this application.

[0028] In the figure: 1-Optical system, 11-First lens group, 111-First lens, 112-Second lens, 12-First reflection structure, 121-Through hole, 13-Second reflection structure, 14-Second lens group, 141-Third lens, 142-Correction lens group, 15-Image plane. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0030] In the following description, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The following description provides multiple embodiments of this application, which can be substituted or combined with each other. Therefore, this application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0031] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this application. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0032] Firstly, see [the following] Figure 1-3This application provides an optical system comprising a first lens group 11, a first reflecting structure 12, a second reflecting structure 13, a second lens group 14, and an image plane 15 arranged sequentially along the optical axis from the object side to the image side; the first reflecting structure 12 and the second reflecting structure 13 are both optical structures for reflecting light; the first lens group 11 includes a first lens 111 with negative optical power and a second lens 112 with positive optical power; a through hole 121 is provided through a first predetermined area of ​​the first reflecting structure 12, and the second lens group 14 is disposed at a position corresponding to the through hole 121; the second reflecting structure 13 is disposed in the first predetermined area of ​​the image-side mirror surface of the first lens group 11; the second lens group 14 includes a third lens 141 with negative optical power, and the third lens 141 is disposed on the object side of the second lens group 14; the ratio of the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 to the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 is greater than or equal to 40% and less than or equal to 80%.

[0033] In this embodiment, the ratio of the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 to the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 is not less than 40% and not greater than 80%, i.e., the ratio of L1 to L2 is 40%-80%. Therefore, the third lens 141 extends between the first reflecting structure 12 and the second reflecting structure 13, thus extending at least a portion of the structure of the second lens group 14 between the first reflecting structure 12 and the second reflecting structure 13. Firstly, this application shortens the overall length of the optical system 1, making the structure more compact. Secondly, if the ratio of the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 to the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 exceeds 80%, the overall length of the optical system 1 will be significantly increased. If the ratio of L1 to L2 is less than 40%, the second lens group 14 will excessively intrude and cut off the light path, leading to additional diffraction effects, aberrations, and a decrease in light transmission. Therefore, the ratio of the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror of the third lens 141 to the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 is set within the above range, achieving controllability of the length dimension of the optical system 1 while balancing optical performance. Thirdly, by using the third lens 141 with negative optical power, this application can cause light to diverge, thereby further increasing the focal length of the optical system 1 and improving the field curvature correction capability. At the same time, it maximizes the utilization of the light-transmitting aperture of the through hole 121 and achieves image-side telecenty, improving the relative illumination of the field of view. The imaging signal-to-noise ratio in the edge region is significantly improved, avoiding edge image quality degradation caused by insufficient illumination, which is especially suitable for low-light environments. In summary, the optical system 1 achieves both a small focal ratio and uniform illumination of the field of view while maintaining miniaturization.

[0034] In this embodiment, the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 can be the shortest distance between them. Similarly, the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 can also be the shortest distance between them. The distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 can also be the distance between a first preset point on the reflecting surface of the second reflecting structure 13 and a second preset point on the object-side mirror surface of the third lens 141. Likewise, the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 can also be the distance between a second preset point on the reflecting surface of the second reflecting structure 13 and a third preset point on the reflecting surface of the first reflecting structure 12.

[0035] In the embodiments of this application, the first lens group 11, which consists of a first lens 111 with negative optical power and a second lens group 14 with positive optical power, plays a role in correcting aberrations such as spherical aberration and coma of the optical system 1, thereby further improving the imaging quality of the optical system 1. Compared with the large meniscus lens used in related technologies, it has a larger centering coefficient, is easier to process, and improves production efficiency and yield.

[0036] In this embodiment, the second lens group 14 is disposed at a position corresponding to the through hole 121. The second reflecting structure 13 reflects the first light reflected by the first reflecting structure 12 again. The first light can pass through the second lens group 14 or pass through the second lens group 14 and the through hole 121 in sequence and reach the image plane 15. The second light reflected by the image plane 15 can pass through the second lens group 14 or pass through the through hole 121 and the second lens group 14 in sequence and reach the second reflecting structure 13.

[0037] In the embodiments of this application, the ratio of L1 to L2 is greater than or equal to 40% and less than or equal to 80%. Therefore, the ratio of L1 to L2 can be one of the following: 40%, 41%, 42%, 43%, 43.6%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 58.9%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 67.4%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, or a range between any two of the above.

[0038] In one possible implementation, the through hole 121 is disposed through the central region of the first reflective structure 12, and the second reflective structure 13 is disposed in the central region of the most image-side mirror surface of the first lens group 11.

[0039] In one possible implementation, the maximum diameter of the second lens group 14 does not exceed the diameter of the through hole 121.

[0040] In this embodiment, the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 can be the distance between the center point of the reflecting surface of the second reflecting structure 13 and the center point of the object-side mirror surface of the third lens 141, and the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 can be the distance between the center point of the reflecting surface of the second reflecting structure 13 and the center point of the reflecting surface of the first reflecting structure 12.

[0041] In one possible implementation, the ratio of the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 to the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 is greater than or equal to 50% and less than or equal to 70%.

[0042] In this embodiment, the distance L1 between the reflecting surface of the second reflecting structure 13 and the object-side mirror surface of the third lens 141 can be the distance between the center point of the reflecting surface of the second reflecting structure 13 and the center point of the object-side mirror surface of the third lens 141, and the distance L2 between the reflecting surface of the second reflecting structure 13 and the reflecting surface of the first reflecting structure 12 can be the distance between the center point of the reflecting surface of the second reflecting structure 13 and the center point of the reflecting surface of the first reflecting structure 12.

[0043] In the embodiments of this application, the ratio of L1 to L2 is a value between 50% and 70%.

[0044] In one possible implementation, the first reflective structure 12 is a first reflector.

[0045] In one possible implementation, the second reflective structure 13 is a second reflector.

[0046] In this embodiment, L1 is the distance between the center point on the reflecting surface of the second mirror and the center point on the object-side mirror surface of the third lens 141, and L2 is the distance between the center point on the reflecting surface of the second mirror and the center point on the reflecting surface of the first mirror.

[0047] In this embodiment, the position of the second lens group 14 is matched with the first reflector and the second reflector, and their distance relationship satisfies the above range, which can maximize the light transmission efficiency inside the optical system 1 and further balance the length, focal ratio and imaging quality of the optical system 1.

[0048] In one possible implementation, the second reflective structure 13 is a reflective film connected to the most image-side mirror surface of the first lens group 11.

[0049] In this embodiment, the second reflective structure 13 is a reflective film coated on the most image-side mirror surface of the first lens group 11.

[0050] In one possible implementation, the ratio of the diameter of the second reflective structure 13 to the diameter of the most image-side lens of the first lens group 11 is less than or equal to 50%.

[0051] In this embodiment, the ratio of the diameter of the second reflective structure 13 to the diameter of the most image-side lens of the first lens group 11 can be 30%-45%.

[0052] In this embodiment, the ratio of the diameter of the second reflective structure 13 to the diameter of the image-side lens of the first lens group 11 is within the aforementioned range. This ensures effective light reflection while suppressing the occlusion ratio of the second lens group 14, thereby shortening the optical path length, improving the system's light transmission efficiency, increasing the signal-to-noise ratio, and achieving miniaturization of the optical system 1 and improving overall imaging quality. The ratio of the diameter of the second reflective structure 13 to the diameter of the image-side lens of the first lens group 11 can be one of 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 32.4%, 33%, 36.3%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 40.8%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, or a value range between any two of the above.

[0053] In one possible implementation, the ratio of the diameter of the through hole 121 to the diameter of the first reflective structure 12 is less than or equal to 40%.

[0054] In this embodiment, the ratio of the diameter of the through hole 121 to the diameter of the first reflective structure 12 can be a value between 20% and 40%.

[0055] In this embodiment, by optimizing the ratio of the diameter of the through-hole 121 to the diameter of the first reflective structure 12, and combining this with the positional design of the negative optical power third lens 141, the optical path is highly folded while maximizing the utilization of the light-transmitting area of ​​the through-hole 121. This further reduces the system length, achieves miniaturization, and improves imaging brightness and contrast, thereby achieving a small focal ratio and improving imaging quality. The ratio of the diameter of the through-hole 121 to the diameter of the first reflective structure 12 can be one of 15%, 16%, 16.9%, 17%, 18%, 19%, 20%, 21%, 21.5%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 36.7%, 37%, 38%, 39%, 40%, or a range between any two of the above values.

[0056] In one possible implementation, the absolute value of the ratio of the focal length f3 of the first reflective structure 12 to the focal length f of the optical system 1 is greater than or equal to 0.4 and less than or equal to 0.5.

[0057] In this embodiment, the ratio of the focal length f3 of the first reflective structure 12 to the focal length f of the optical system 1 satisfies: 0.4 ≤ |f3 / f| ≤ 0.5. Setting the absolute value of the f3 / f ratio within this range reduces the magnification and aperture of the first reflective structure 12, thereby preventing the second lens group 14 extending into the optical system 1 from obstructing the optical path, improving the system's light transmission efficiency and imaging brightness; and improving the aberration balance between the first reflective structure 12 and the second reflective structure 13, resulting in smaller spherical aberration and coma, making correction easier, especially in the field edge region where aberrations are smaller, leading to higher imaging clarity.

[0058] In the embodiments of this application, |f3 / f| can be one of 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5 or a range of values ​​between any two of the above.

[0059] In one possible implementation, the first lens 111 and the second lens 112 are arranged sequentially along the optical axis from the object side to the image side.

[0060] In this embodiment, the first lens 111 with negative optical power is mainly used to compensate for the spherical aberration of the optical system 1; the second lens 112 with positive optical power utilizes the balance between positive and negative optical power to make the red and blue wavelengths coincide on the image plane, greatly reducing axial chromatic aberration and magnification chromatic aberration, and further adjusting the system focal ratio.

[0061] In one possible implementation, the object-side mirror surface of the first lens 111 is concave and the image-side mirror surface is convex.

[0062] And / or, the image-side mirror surface of the second lens 112 is convex.

[0063] In this embodiment, the object-side mirror of the first lens 111 is concave, and the image-side mirror of the first lens 111 is convex, forming a meniscus structure. This structure can maintain negative optical power while making the refraction angles of the incident and outgoing light closer to the optical axis, thereby reducing higher-order spherical aberrations and coma caused by large incident tilt angles. In addition, the field curvature of the meniscus lens is small, which can improve the flatness of the image plane 15 and improve the edge imaging quality.

[0064] In this embodiment, in conjunction with the convex surface structure of the image-side mirror of the second lens 112, in addition to correcting aberrations, a reflective film can be coated or deposited in the central region of the image-side mirror of the second lens 112 to serve as a second reflective structure 13. This allows it to simultaneously function as both a lens and a reflective structure, eliminating the need for a separate reflector element and its mounting space, further shortening the overall length of the optical system 1. It also reduces assembly and adjustment steps and accumulated tolerances, improving the stability and imaging consistency of the optical system 1.

[0065] In one possible implementation, the absolute value of the ratio of the focal length f1 of the first lens 111 to the focal length f2 of the second lens 112 is greater than or equal to 1 and less than or equal to 2.

[0066] In this embodiment, the ratio of the focal length of the first lens 111 to the focal length of the second lens 112 satisfies: 1 ≤ |f1 / f2| ≤ 2. When the ratio of the focal length of the first lens 111 to the focal length of the second lens 112 is within the above range, various aberrations such as spherical aberration, chromatic aberration, and coma can cancel each other out. The optical system 1 achieves near-diffraction-limited imaging performance across the entire field of view, resulting in extremely high resolution and fidelity.

[0067] In the embodiments of this application, |f1 / f2| can be one of 1, 1.02, 1.03, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75, 1.8, 1.9, 2 or a range of values ​​between any two of the above.

[0068] In one possible implementation, the focal ratio of the optical system 1 is greater than or equal to 3 and less than or equal to 6.

[0069] In this embodiment, the focal ratio of the optical system 1 satisfies: 3 ≤ f / D ≤ 6, where f is the focal length of the optical system 1 and D is the aperture of the optical system 1. Through the overall structural design of the optical system 1, the ratio of focal length f to aperture can be significantly reduced.

[0070] In the embodiments of this application, f / D can be one of 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.78, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6 or a range of values ​​between any two of the above.

[0071] In one possible implementation, the ratio of the distance L0 between the object-side mirror surface and the image surface 15 of the first lens group 11 to the focal length f of the optical system 1 is not less than 0.2 and not greater than 0.5.

[0072] In this embodiment, the distance L0 from the object-side mirror of the first lens group 11 to the image plane 15 can be the distance between the center point of the object-side mirror of the first lens group 11 and the center point of the image plane 15. The ratio of the distance L0 between the object-side mirror of the first lens 111 and the image plane 15 to the focal length f of the optical system 1 satisfies: 0.2 ≤ L0 / f ≤ 0.5, preferably 0.28 ≤ L0 / f ≤ 0.43. Through the overall structural design of the optical system 1, the overall length is controllable while maintaining a long focal length, thus achieving miniaturization of the optical system 1.

[0073] In the embodiments of this application, L0 / f can be one of 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5 or a range of values ​​between any two of the above.

[0074] In one possible implementation, the radius of the RMS spot in the field of view of the optical system 1 does not exceed 1.5 times the radius of the Airy disk, and the radius of the GEO spot does not exceed 3 times the radius of the Airy disk.

[0075] In the embodiments of this application, "Airy disk radius" has a well-known meaning in the art. Specifically, it refers to the distance from the first dark ring of the light spot formed at the focal point to the center when a point light source is imaged by a diffraction-limited optical system 1. It can be tested using methods known in the art. "RMS spot radius" has a well-known meaning in the art. Specifically, it refers to the root mean square radius of the light rays distributed on the image plane 15, reflecting the average diffusion degree of the light spot, also known as the "root mean square spot radius," and can be tested using methods known in the art. "GEO spot radius" has a well-known meaning in the art. Specifically, it refers to the maximum radial distance from the geometric center of the light spot to the outermost light ray, also known as the "maximum geometric spot radius," and can be tested using methods known in the art.

[0076] In the embodiments of this application, the RMS spot radius not exceeding 1.5 times the Airy disk radius indicates that most of the light energy is concentrated near the Airy disk; the GEO spot radius not exceeding 3 times the Airy disk radius indicates that even the worst-imaged part is very close to the center. The optical system 1 successfully corrects various types of aberrations, and the overall energy distribution of the image plane 15 is concentrated and uniform, with high contrast and high resolution.

[0077] In this embodiment, the Airy disk radius and the RMS spot radius within the field of view are two key parameters for evaluating the imaging quality of optical system 1, representing the theoretical minimum spot size under the diffraction limit and the spot size caused by actual aberrations, respectively. The Airy disk radius is the theoretical benchmark for the diffraction limit, determined by circular aperture diffraction, and represents the minimum spot size for imaging from a point source in an ideal aberration-free system. This value is an inevitable result of physical diffraction effects and cannot be exceeded; it is often used as the theoretical limit for imaging quality. The RMS spot radius quantifies the light dispersion caused by actual aberrations. It is obtained by calculating the root mean square distance from all light rays falling within the field of view to a reference point (such as the centroid of the spot), reflecting the statistical concentration of light energy: the smaller the RMS value, the better the aberration control and the more concentrated the energy. The core of the relationship between the two lies in comparing the size of the RMS and the Airy disk radius. When the RMS spot radius is close to or smaller than the Airy disk radius, the system is close to the diffraction limit, and the imaging quality is excellent; if the RMS is significantly larger than the Airy disk radius, then aberrations dominate the imaging blur. Specifically: RMS < Airy disk radius: The system's energy concentration is close to the theoretical limit, and the modulation transfer function (MTF) is close to the diffraction limit, limiting the scope for optimization. RMS ≈ Airy disk radius: The system is near the diffraction limit, a target for high-quality optical design. RMS > Airy disk radius: Significant aberrations require further optimization to reduce wavefront error. In practical applications, a comprehensive evaluation combining the geometric radius (GEO) is necessary. GEO represents the radius of the smallest central circle containing all rays, emphasizing geometric inclusion; when the difference between RMS and GEO is large (e.g., GEO > 3 × RMS), irregular spot shapes (e.g., elongated) may affect imaging, requiring attention to aberration correction. Furthermore, the choice of reference point (e.g., centroid or principal ray image point) affects the RMS value, and careful selection based on design objectives is necessary in off-axis fields of view.

[0078] In one possible implementation, the relative illumination of the edge field of view of the optical system 1 is greater than or equal to 90%.

[0079] In this embodiment, the relative illumination of the edge field of view is ≥90%. By optimizing the power distribution and position adjustment of multiple lens groups, the relative illumination of the edge field of view is effectively improved while miniaturizing the optical system 1. At the maximum field of view, the relative illumination of the edge field of view is still greater than 90%, resulting in high imaging quality with uniform brightness and no obvious vignetting.

[0080] In the embodiments of this application, the relative illumination of the edge field of view can be one of 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.3%, 98.5%, 99%, 99.5%, 99.9% or any two of the above values.

[0081] In one possible implementation, the second lens group 14 further includes a positive optical power correction lens group 142.

[0082] In this embodiment, the correction lens group 142 may include a fourth lens and a fifth lens. The object-side mirror surface of the fourth lens is flat, the radius of curvature of the image-side mirror surface is -73.80 mm, and the center thickness is 8.2 mm; the distance between the object-side mirror surface of the fourth lens and the object-side mirror surface of the fifth lens is 0.2 mm; the radius of curvature of the object-side mirror surface of the fifth lens is 73.80 mm, the image-side mirror surface is flat, and the center thickness is 8.2 mm; the distance between the center point of the image-side mirror surface of the fifth lens and the center point of the image plane 15 is 25.174 mm.

[0083] In this embodiment of the application, the correction module includes a correction mirror. The object-side mirror of the correction mirror has a radius of curvature of -182.234 mm, the image-side mirror has a radius of curvature of -64.236 mm, and the center thickness is 2.632 mm. The distance between the image-side mirror of the correction mirror and the image plane 15 is 39.962 mm.

[0084] In a second aspect, this application provides an optical lens, including a lens barrel and an optical system 1 as described in any of the first aspects, wherein the optical system 1 is installed inside the lens barrel.

[0085] Example 1

[0086] See Figure 1 An optical system includes a first lens group 11, a first reflecting structure 12, a second reflecting structure 13, a second lens group 14, and an image plane 15 arranged sequentially along the optical axis from the object side to the image side. The first lens group 11 includes a first lens 111 with negative optical power and a second lens 112 with positive optical power. The first reflecting structure 12 has a through hole 121 in its central region. The second reflecting structure 13 is disposed in the central region of the image-side lens of the first lens group 11. The second lens group 14 includes a third lens 141 with negative optical power, and the third lens 141 is disposed on the object side of the second lens group 14. The ratio of the distance L1 from the center point of the reflecting surface of the second reflecting structure 13 to the center point of the object-side mirror of the third lens 141 to the distance L2 from the center point of the reflecting surface of the second reflecting structure 13 to the center point of the reflecting surface of the first reflecting structure 12 is 58.9%.

[0087] The second reflective structure 13 is a reflective film coated on the central region of the image-side mirror surface of the second lens 112.

[0088] The second lens group 14 also includes a correction lens group 142 with positive optical power, the correction lens group 142 including a fourth lens and a fifth lens.

[0089] The object-side mirror surface of the first lens 111 has a radius of curvature of -168.40 mm, the image-side mirror surface has a radius of curvature of -311.86 mm, and a center thickness of 5 mm; the distance between the center point of the image-side mirror surface of the first lens 111 and the center point of the object-side mirror surface of the second lens 112 is 0.8 mm.

[0090] The second lens 112 has an object-side mirror surface with a radius of curvature of -1200.00 mm, an image-side mirror surface with a radius of curvature of -285.62 mm, a center thickness of 8 mm, and a diameter of 98 mm. The distance between the center point of the image-side mirror surface of the second lens 112 and the center point of the reflecting surface of the first reflecting structure 12 is 96 mm.

[0091] The first reflecting structure 12 is a first reflecting mirror. The radius of curvature of the reflecting surface of the first reflecting mirror is -311.25 mm, and the diameter is 98 mm. The diameter of the through hole 121 in the central region of the first reflecting structure 12 is 36 mm. The distance between the center point of the reflecting surface of the first reflecting mirror and the center point of the reflecting surface of the second reflecting structure 13 is 96 mm.

[0092] The first lens 111 and the second lens 112 are arranged sequentially along the optical axis from the object side to the image side; the radius of curvature of the image side mirror of the second lens 112 is -285.62mm and the diameter is 40mm; the distance between the center point of the reflecting surface of the second reflecting structure 13 and the center point of the object side mirror of the third lens 141 is 56.5mm.

[0093] The object-side mirror surface of the third lens 141 has a radius of curvature of -134.73 mm, the image-side mirror surface has a radius of curvature of 45.41 mm, and a center thickness of 4.4 mm; the distance between the center point of the object-side mirror surface of the third lens 141 and the center point of the object-side mirror surface of the fourth lens is 28.46 mm.

[0094] The object-side mirror of the fourth lens is flat, the radius of curvature of the image-side mirror is -73.80 mm, and the thickness of the central region is 8.2 mm; the distance between the center point of the object-side mirror of the fourth lens and the center point of the object-side mirror of the fifth lens is 0.2 mm; the radius of curvature of the object-side mirror of the fifth lens is 73.80 mm, the image-side mirror is flat, and the thickness of the central region is 8.2 mm; the distance between the center point of the image-side mirror of the fifth lens and the center point of the image plane 15 is 25.174 mm.

[0095] The optical system described above has the following specifications:

[0096] Focal length: f = 339.92 mm; Focal ratio: f / D = 3.78; Wavelength range: 0.43 μm - 0.68 μm; Total length of optical system: 145 mm.

[0097] In this embodiment, the Airy disk radius in the full field-of-view dot matrix diagram is 2.708 μm; the RMS spot radius is ≤1.666 μm, and the RMS spot radius does not exceed 1.5 times the Airy disk radius; the GEO spot radius is ≤3.458 μm, and the GEO spot radius does not exceed 3 times the Airy disk radius.

[0098] In this embodiment, the relative illuminance map of the field of view still maintains 98.29% relative illuminance at the edge of the field of view, with very little difference from the relative illuminance near the center. This indicates that the brightness of this embodiment is uniform and there are no obvious dark corners throughout the entire field of view.

[0099] This optical system achieves a compact overall length while maintaining high light throughput and a long focal length. The optical system in this embodiment delivers excellent imaging quality across the entire field of view, and its low focal ratio of 3.78 significantly reduces single-frame exposure time in astronomical and dynamic photography.

[0100] Example 2

[0101] See Figure 2 An optical system includes a first lens group 11, a first reflecting structure 12, a second reflecting structure 13, a second lens group 14, and an image plane 15 arranged sequentially along the optical axis from the object side to the image side. The first lens group 11 includes a first lens 111 with negative optical power and a second lens 112 with positive optical power. The first reflecting structure 12 has a through hole 121 in its central region. The second reflecting structure 13 is disposed in the central region of the image-side lens of the first lens group 11. The second lens group 14 includes a third lens 141 with negative optical power, and the third lens 141 is disposed on the object side of the second lens group 14. The ratio of the distance L1 from the center point of the reflecting surface of the second reflecting structure 13 to the center point of the object-side mirror of the third lens 141 to the distance L2 from the center point of the reflecting surface of the second reflecting structure 13 to the center point of the reflecting surface of the first reflecting structure 12 is 66.0%.

[0102] The second reflective structure 13 is a reflective film coated on the central region of the image-side mirror surface of the second lens 112.

[0103] The second lens group 14 also includes a correction mirror with positive optical power.

[0104] The object-side mirror surface of the first lens 111 has a radius of curvature of -157.218 mm, the image-side mirror surface has a radius of curvature of -8286.006 mm, and a center thickness of 7.334 mm. The distance between the center point of the image-side mirror surface of the first lens 111 and the center point of the object-side mirror surface of the second lens 112 is 10.301 mm.

[0105] The second lens 112 has an object-side mirror surface with a radius of curvature of -2420.332 mm, an image-side mirror surface with a radius of curvature of -170.899 mm, a center thickness of 10 mm, and a diameter of 97.8 mm. The distance between the center point of the image-side mirror surface of the second lens 112 and the center point of the object-side mirror surface of the first reflecting structure 12 is 95.269 mm.

[0106] The first reflecting structure 12 is a first reflecting mirror. The radius of curvature of the object-side mirror surface of the first reflecting mirror is -165.765 mm, the radius of curvature of the reflecting surface is -250.091 mm, the center thickness is 9 mm, and the diameter is 99.56 mm. The diameter of the through hole 121 in the central region of the first reflecting structure 12 is 16.8 mm. The distance between the center point of the object-side mirror surface of the first reflecting mirror and the center point of the reflecting surface of the second reflecting structure 13 is 95.269 mm.

[0107] The first lens 111 and the second lens 112 are arranged sequentially along the optical axis from the object side to the image side; the second lens 112 has a radius of curvature of -170.599 mm and a diameter of 35.47 mm; the distance between the center point of the reflecting surface of the second reflecting structure 13 and the center point of the object-side mirror surface of the third lens 141 is 68.779 mm.

[0108] The object-side mirror surface of the third lens 141 has a radius of curvature of 68.635 mm, the image-side mirror surface has a radius of curvature of 30.068 mm, and a center thickness of 2.5 mm; the distance between the center point of the object-side mirror surface of the third lens 141 and the center point of the object-side mirror surface of the fourth lens is 2.37 mm.

[0109] The object-side mirror surface of the fourth lens has a radius of curvature of -182.234 mm, the image-side mirror surface has a radius of curvature of -64.236 mm, and the center thickness is 2.632 mm; the distance between the center point of the image-side mirror surface of the fourth lens and the center point of the image surface 15 is 39.962 mm.

[0110] The optical system described above has the following specifications:

[0111] Focal length: f = 350mm; Focal ratio: f / D = 3.89; Wavelength range: 0.43μm-0.68μm; Total length of optical system: 143.89mm.

[0112] In this embodiment, the Airy disk radius in the full field of view is 2.786 μm; the RMS spot radius is ≤2.674 μm, and the RMS spot radius does not exceed 1.5 times the Airy disk radius; the GEO spot radius is ≤7.594 μm, and the GEO spot radius does not exceed 3 times the Airy disk radius.

[0113] Example 3

[0114] Reference Figure 3 An optical system includes a first lens group 11, a first reflecting structure 12, a second reflecting structure 13, a second lens group 14, and an image plane 15 arranged sequentially along the optical axis from the object side to the image side. The first lens group 11 includes a first lens 111 with negative optical power and a second lens 112 with positive optical power. The first reflecting structure 12 has a through-hole 121 in its central region. The second reflecting structure 13 is disposed in the central region of the image-side lens of the first lens group 11. The second lens group 14 includes a third lens 141 with negative optical power, which is disposed on the object side of the second lens group 14. The ratio of the distance L1 from the center point of the reflecting surface of the second reflecting structure 13 to the center point of the object-side mirror of the third lens 141 to the distance L2 from the center point of the second reflecting structure 13 to the center point of the reflecting surface of the first reflecting structure 12 is 66.0%.

[0115] The second reflective structure 13 is a reflective film coated on the central region of the image-side mirror surface of the second lens 112.

[0116] The object-side mirror surface of the first lens 111 has a radius of curvature of -292.462 mm, the image-side mirror surface has a radius of curvature of -1614.226 mm, and a center thickness of 5 mm; the distance between the center point of the image-side mirror surface of the first lens 111 and the center point of the object-side mirror surface of the second lens 112 is 9.542 mm.

[0117] The second lens 112 has an object-side mirror surface with a radius of curvature of 1224.946 mm, an image-side mirror surface with a radius of curvature of -173.448 mm, a center thickness of 9.542 mm, and a diameter of 91.9 mm; the distance between the center point of the image-side mirror surface of the second lens 112 and the center point of the object-side mirror surface of the first reflecting structure 12 is 99.978 mm.

[0118] The first reflecting structure 12 is a first reflecting mirror. The radius of curvature of the object-side mirror surface of the first reflecting mirror is -173.207 mm, the radius of curvature of the reflecting surface is -316.423 mm, the center thickness is 8.989 mm, and the diameter is 78.42 mm. The diameter of the through hole 121 in the central region of the first reflecting structure 12 is 16.86 mm. The distance between the center point of the object-side mirror surface of the first reflecting mirror and the center point of the reflecting surface of the second reflecting structure 13 is 99.978 mm.

[0119] The first lens 111 and the second lens 112 are arranged sequentially along the optical axis from the object side to the image side. The second lens 112 has a radius of curvature of -173.448 mm and a diameter of 29.78 mm. The distance between the center point of the reflecting surface of the second reflecting structure 13 and the center point of the object-side mirror surface of the third lens 141 is 73.512 mm.

[0120] The object-side mirror of the third lens 141 has a radius of curvature of 23.339 mm, the image-side mirror has a radius of curvature of 17.181 mm, and a center thickness of 9 mm; the distance between the center point of the object-side mirror of the third lens 141 and the center point of the image plane 15 is 52.909 mm.

[0121] The optical system described above has the following specifications:

[0122] Focal length: f = 540mm; Focal ratio: f / D = 6; Wavelength range: 0.43μm-0.68μm; Total length of optical system: 149.963mm.

[0123] In this embodiment, the Airy disk radius in the dot pattern under full field of view is 4.295 μm; the RMS spot radius is ≤5.412 μm, and the RMS spot radius does not exceed 1.5 times the Airy disk radius; the GEO spot radius is ≤11.225 μm, and the GEO spot radius does not exceed 3 times the Airy disk radius.

[0124] The above-described contents can be implemented individually or in various combinations, and these variations are all within the protection scope of this invention.

[0125] It should be noted that in the description of this application, the terms "upper end," "lower end," and "bottom end," indicating orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise limited, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical system characterized by: The optical system (1) comprises, in order from the object side to the image side along the optical axis, a first lens group (11), a first reflection structure (12), a second reflection structure (13), a second lens group (14), and an image plane (15); the first reflection structure (12) and the second reflection structure (13) are optical structures for reflecting light; the first lens group (11) comprises a first lens (111) with negative refractive power and a second lens (112) with positive refractive power; a through hole (121) is provided in a first preset region of the first reflection structure (12), and the second lens group (14) is arranged at a position corresponding to the through hole (121); the second reflection structure (13) is arranged at a first preset region of the most image-side lens surface of the first lens group (11). The second lens group (14) comprises a third lens (141) with negative refractive power, and the third lens (141) is arranged at the most object-side of the second lens group (14); the ratio of the distance L1 between the reflection surface of the second reflection structure (13) and the object-side lens surface of the third lens (141) to the distance L2 between the reflection surface of the second reflection structure (13) and the reflection surface of the first reflection structure (12) is greater than or equal to 40% and less than or equal to 80%.

2. An optical system as claimed in claim 1, characterized in that: The through hole (121) is provided in the central region of the first reflection structure (12), and the second reflection structure (13) is arranged in the central region of the most image-side lens surface of the first lens group (11).

3. An optical system as claimed in claim 2, characterized in that: The ratio of the distance L1 between the reflection surface of the second reflection structure (13) and the object-side lens surface of the third lens (141) to the distance L2 between the reflection surface of the second reflection structure (13) and the reflection surface of the first reflection structure (12) is greater than or equal to 50% and less than or equal to 70%.

4. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The second reflection structure (13) is a reflection film connected to the most image-side lens surface of the first lens group (11).

5. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The ratio of the diameter of the second reflection structure (13) to the diameter of the most image-side lens surface of the first lens group (11) is less than or equal to 50%, and the ratio can be selected to be 30%-45%.

6. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The ratio of the diameter of the through hole (121) to the diameter of the first reflection structure (12) is less than or equal to 40%, and the ratio can be selected to be 20%-40%.

7. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The absolute value of the ratio of the focal length f3 of the first reflection structure (12) to the focal length f of the optical system (1) is greater than or equal to 0.4 and less than or equal to 0.

5.

8. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The first lens (111) and the second lens (112) are arranged in order from the object side to the image side along the optical axis.

9. An optical system as claimed in claim 8, characterized in that: The object-side lens surface of the first lens (111) is a concave surface, and the image-side lens surface is a convex surface. The image-side lens surface of the second lens (112) is a convex surface.

10. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The absolute value of the ratio of the focal length f1 of the first lens (111) to the focal length f2 of the second lens (112) is greater than or equal to 1 and less than or equal to 2.

11. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The focal ratio of the optical system (1) is greater than or equal to 3 and less than or equal to 6.

12. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The ratio of the distance L0 between the most object side mirror surface of the first lens group (11) and the image surface (15) to the focal length f of the optical system (1) is greater than or equal to 0.2 and less than or equal to 0.5, and can be greater than or equal to 0.28 and less than or equal to 0.

43.

13. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The RMS spot radius in the field of view of the optical system (1) is not more than 1.5 times the Airy disk radius, and the GEO spot radius is not more than 3 times the Airy disk radius.

14. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The relative illumination in the edge field of view of the optical system (1) is greater than or equal to 90%.

15. An optical system as claimed in claim 1 or 2 or 3, characterized in that: The second lens group (14) further comprises a correction lens group (142) with positive refractive power.

16. An optical lens characterized in that: An optical system (1) as claimed in any one of claims 1 to 15 is mounted in a lens barrel.

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