periscopic mirror lens

Abstract

This invention discloses a periscope reflecting lens, comprising an aperture stop, a refractive element group, a reflecting element, and a color filter. The refractive element group includes a first lens, a second lens, a third lens, and a fourth lens. The first lens has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens has negative optical power, with a convex object-side surface and a concave image-side surface. The third lens has positive optical power, with a concave object-side surface and a convex image-side surface. The fourth lens has positive optical power, with a concave object-side surface and a convex image-side surface. The reflecting element is disposed on the side of the refractive element group facing the image end, and the reflecting surface forms a predetermined angle with the incident optical axis and the outgoing optical axis, respectively. This invention solves the problems of traditional periscope lenses by using a front-mounted aperture stop, four lenses with a combination of positive and negative optical power, and a reflecting mirror to effectively correct advanced aberrations. While achieving long focal length characteristics, it shortens the overall length of the lens, meeting the needs of portable devices such as mobile phones for thinness and high image quality.

Description

Technical Field

[0001] This invention relates to the field of imaging lens technology, and in particular to a periscope reflecting lens. Background Technology

[0002] With the increasing prevalence and upgrading of imaging capabilities on mobile devices, telephoto lenses with long-range shooting capabilities have become an essential feature of smartphones. Due to structural limitations, the total optical length (TTL) of conventional telephoto lenses is generally quite long, making it unsuitable for the design requirements of today's consumer electronics devices that prioritize slim and lightweight bodies. The periscope lens structure was thus proposed, utilizing the principle of light refracting through reflective surfaces to change the distribution of lens dimensions, transforming the vertical physical length into the horizontal dimension, thereby achieving the goal of mounting a telephoto optical system within a limited space.

[0003] Existing periscope telephoto lenses mostly use right-angle prisms as optical path deflectors, positioned on the lens's incident light side. This classic design has significant drawbacks: firstly, right-angle prism optical elements are expensive to produce, and the overall weight of the prism is also relatively large, hindering the lightweighting of the lens module; secondly, because the prism is located at the front of the refractive element group (near the system pupil), the additional chromatic aberration and off-axis aberrations it introduces severely restrict the aberration correction capabilities of the subsequent refractive element group, making it difficult to achieve breakthroughs in lens resolution and simultaneously meet the design requirements of structural miniaturization and high image quality. Based on these issues, the industry urgently needs to explore new periscope lens design approaches to resolve the challenges of cost control, image quality, and miniaturization while maintaining stable telephoto shooting performance. Summary of the Invention

[0004] To address the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a periscope reflecting lens that forms a catadioptric optical system by reasonably configuring refractive and reflective elements, thereby avoiding the disadvantages of high cost and heavy weight of traditional right-angle prisms, while improving the aberration characteristics of the optical system. Under the premise of achieving telephoto shooting, it also takes into account the design requirements of miniaturization, lightweighting and high imaging performance of the lens module.

[0005] To solve the above technical problem, one technical solution adopted by the present invention is: provide a periscopic reflection lens, comprising a stop, a refraction element group, a reflection element and a color filter arranged sequentially from the object side to the image side along the optical axis direction, wherein the refraction element group comprises a first lens, a second lens, a third lens and a fourth lens arranged sequentially from the object side to the image side along the optical axis direction; the first lens has positive optical power, an object side surface thereof is a convex surface, and an image side surface thereof is a concave surface; the second lens has negative optical power, an object side surface thereof is a convex surface, and an image side surface thereof is a concave surface; the third lens has positive optical power, an object side surface thereof is a concave surface, and an image side surface thereof is a convex surface; the fourth lens has positive optical power, an object side surface thereof is a concave surface, and an image side surface thereof is a convex surface; the reflection element is arranged on a side of the refraction element group facing the image side, light is incident on the reflection element along an incident optical axis, and exits to an imaging surface along an exit optical axis after passing through a reflecting surface of the reflection element; the reflecting surface forms predetermined angles with the incident optical axis and the exit optical axis respectively; a refractive index of the first lens is smaller than a refractive index of the second lens.

[0006] Further, a ratio of an optical back focal length BFL to a total optical length TTL of the periscopic reflection lens satisfies 0.65 < BFL / TTL < 0.8.

[0007] Further, a ratio of a focal length f of the periscopic reflection lens to the total optical length TTL satisfies 0.8 < f / TTL < 1.

[0008] Further, an entrance pupil diameter of the periscopic reflection lens = focal length f / F-number FNO, and the entrance pupil diameter of the periscopic reflection lens satisfies 4 mm < f / FNO < 5 mm.

[0009] Further, an absolute value of distortion of the periscopic reflection lens is less than 1% within the full field of view range.

[0010] Further, a clear half-aperture DM1 of the first lens and a clear half-aperture DM4 of the fourth lens satisfy 1 < DM1 / DM4 < 1.25, so that the light travels gently.

[0011] Further, refractive indices of the first lens, the third lens and the fourth lens are all ≤ 1.60, and a refractive index of the second lens is ≥ 1.60.

[0012] Further, Abbe numbers of the first lens, the third lens and the fourth lens are greater than or equal to 30, and an Abbe number of the second lens is less than 30.

[0013] Further, the first lens, the second lens, the third lens and the fourth lens are all aspheric lenses, and the reflection element is a coated reflecting mirror.

[0014] Further, the first lens, the second lens, the third lens and the fourth lens are all made of resin material.

[0015] The periscopic reflective lens of the present invention has at least the following beneficial effects: firstly, four lenses arranged in positive-negative-positive-positive optical power are adopted, and cooperate with the front-placed diaphragm design, which effectively reduces the total length of the system, enabling the ratio of the focal length f to the total optical length TTL to satisfy 0.8 < f / TTL < 1, ensuring that the lens still has a large focal length under the condition of a short total length, and realizing the periscopic telephoto function; secondly, the four lenses adopt the refractive index collocation of low refractive index, high refractive index, low refractive index and low refractive index, so that the system obtains good aberration correction while chromatic aberration is also effectively controlled; meanwhile, BFL / TTL satisfies 0.65 < BFL / TTL < 0.8, so that the back focal length occupies a large proportion of the total length, providing necessary physical space for the refraction and reflection of the optical path at the reflective element, and also facilitating further correction of aberrations; furthermore, the clear half-aperture DM1 of the first lens and the clear half-aperture DM4 of the fourth lens satisfy 1 < DM1 / DM4 < 1.25, which makes the propagation trend of light tend to be gentle, and makes the beam area reaching the reflective element relatively small, thereby effectively reducing the size of the reflective element and further contributing to the miniaturization of the lens module; furthermore, all four lenses are aspheric resin lenses, the aspheric design provides more degrees of freedom to correct various aberrations, so that the absolute value of the system distortion is less than 1.2% in the full field of view, field curvature and coma are well controlled, and the resin material further reduces the manufacturing cost and the weight of the lens; finally, a coated reflector is used to replace the right-angle prism generally used in the prior art, which realizes optical path turning while making the overall production cost of the lens lower and the weight lighter; in summary, the present invention forms a catadioptric optical system through the refraction element group and the reflection element, and the two cooperate to achieve long focal length and high image quality in a limited space, and has superior aberration correction capability and lower manufacturing cost compared with the prior art. Description of Drawings

[0016] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The schematic embodiments of the present application and the descriptions thereof are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings: Figure 1 is a structural schematic diagram of the first embodiment of the periscopic reflective lens of the present invention; Figure 2 is an optical path simulation diagram of the reflecting surface inclined at 45° in the first embodiment of the periscopic reflective lens of the present invention; Figure 3 is an optical path simulation diagram of the reflecting surface inclined at 42° in the first embodiment of the periscopic reflective lens of the present invention; Figure 4 is an MTF diagram of the first embodiment of the periscopic reflective lens of the present invention; Figure 5 This is a field curvature and distortion test diagram of a first embodiment of the periscope reflecting lens of the present invention; Figure 6 This is a test diagram of lateral chromatic aberration of a periscope reflecting lens according to a first embodiment of the present invention; Figure 7 This is a longitudinal chromatic aberration test diagram of a first embodiment of the periscope reflecting lens of the present invention; Figure 8 This is a dot diagram of a first embodiment of the periscope reflecting lens of the present invention.

[0017] Figure 9 This is a simulated optical path diagram of the periscope reflecting lens embodiment two of the present invention, in which the reflecting surface is tilted at 45°. Figure 10 This is the MTF diagram of a second embodiment of the periscope reflecting lens of the present invention; Figure 11 This is a field curvature and distortion test diagram of a second embodiment of the periscope reflecting lens of the present invention; Figure 12 This is a test diagram of lateral chromatic aberration in Embodiment 2 of the periscope reflecting lens of the present invention; Figure 13 This is a longitudinal chromatic aberration test diagram of a second embodiment of the periscope reflecting lens of the present invention; Figure 14 This is a dot diagram of a second embodiment of the periscope reflecting lens of the present invention; Figure 15 This is a simulated optical path diagram of the periscope reflecting lens embodiment three of the present invention, in which the reflecting surface is tilted at 45°. Figure 16 This is the MTF diagram of a third embodiment of the periscope reflecting lens of the present invention; Figure 17 This is a field curvature and distortion test diagram of a third embodiment of the periscope reflecting lens of the present invention; Figure 18 This is a test diagram of lateral chromatic aberration in Embodiment 3 of the periscope reflecting lens of the present invention; Figure 19 This is a longitudinal chromatic aberration test diagram of a third embodiment of the periscope reflecting lens of the present invention; Figure 20 This is a dot diagram of a third embodiment of the periscope reflecting lens of the present invention.

[0018] The meanings of the labels in the attached diagram are as follows: Aperture 1, refractive element group 2, first lens 21, second lens 22, third lens 23, fourth lens 24, reflective element 3, color filter 4. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The following disclosure provides various embodiments or examples for implementing different features of the invention. Specific examples of components and arrangements will be described below to simplify the invention. Of course, these are merely examples and are not intended to limit the invention. For example, in the following description, forming a first component above or on a second component may include embodiments where the first and second components are in direct contact, or embodiments where other components may be formed between the first and second components such that the first and second components are not in direct contact. Furthermore, reference numerals and / or characters may be repeated in various instances of the invention. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations.

[0021] Furthermore, spatial relation terms such as "below," "under," "below," "above," and "above" may be used herein to readily describe the relationship between one element or component and another element (or component) or component (or component) as shown in the figure. In addition to the orientations shown in the figure, spatial relation terms will encompass various different orientations of the device in use or operation. The device may be positioned in other ways (rotated 90 degrees or in other orientations) and will be interpreted accordingly through the spatial relation descriptors used herein.

[0022] Furthermore, the technical parts described in this invention and the appended claims are primarily the improved technical parts of this invention, and do not limit the object protected by this invention to only having these technical parts. Other known essential components (structures and / or methods) and / or non-essential components of the object protected, besides the technical parts described in this invention and the appended claims, are not included in this invention and the appended claims because they do not fall within the scope of improvements of this invention; however, this does not mean that the object protected by this invention does not possess these known components.

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] Example 1: Please refer to Figure 1, the periscope reflection lens of the present invention comprises a stop 1, a refraction element group 2, a reflection element 3 and a filter 4. The stop 1, the refraction element group 2, the reflection element 3 and the filter 4 are arranged sequentially from the object side to the image side along the optical axis direction. The refraction element group 2 comprises a first lens 21, a second lens 22, a third lens 23 and a fourth lens 24 which are arranged sequentially from the object side to the image side along the optical axis direction.

[0025] The first lens 21 has positive optical power, the object side surface thereof is a convex surface, and the image side surface thereof is a concave surface. It can preliminarily converge light, contributing a basic part to the focal length of the entire system, and the classic positive meniscus lens also has a relatively significant effect on the correction of spherical aberration and coma; the refractive index of the first lens 21 is ≤ 1.60, and the Abbe number of the first lens 21 is ≥ 30. The relatively high Abbe number means that the chromatic dispersion introduced by the lens itself is small, which avoids introducing serious chromatic aberration from the very beginning.

[0026] The second lens 22 has negative optical power, the object side surface thereof is a convex surface, and the image side surface thereof is a concave surface. The refractive index of the second lens 22 is ≥ 1.60, and the Abbe number of the second lens 22 is less than 30. It should be noted that the refractive index of the second lens 22 is higher than that of the first lens 21. Since a material with a higher refractive index has a lower Abbe number, it will introduce more serious chromatic aberration for the refraction element group 2. Therefore, the first lens 21 is made of a low-refractive-index material, so that the chromatic aberration introduced by the first lens 21 is small, while the second lens 22 is made of a high-refractive-index material, which plays a role in controlling spherical aberration and field curvature. At this time, since the first lens 21 has controlled the chromatic aberration to a low value, even if the second lens 22 adopts a material with a higher refractive index, the total amount of chromatic aberration correction that needs to be borne is still small.

[0027] The third lens 23 has positive optical power, the object side surface thereof is a concave surface, and the image side surface thereof is a convex surface. The refractive index of the third lens 23 is ≤ 1.60, and the Abbe number of the third lens 23 is ≥ 30.

[0028] The fourth lens 24 has positive optical power, the object side surface thereof is a concave surface, and the image side surface thereof is a convex surface. The clear half-aperture DM4 of the fourth lens 24 and the clear half-aperture DM1 of the first lens 21 satisfy 1 < DM1 / DM4 < 1.25, which ensures that the light propagation trend in the system is relatively gentle, enables the light beam to have a relatively small area when the light subsequently enters the reflection element 3, and can effectively reduce the size of the reflection element 3. The refractive index of the fourth lens 24 is ≤ 1.60, and the Abbe number of the fourth lens 24 is ≥ 30.

[0029] Each of said first lens (21), said second lens (22), said third lens (23) and said fourth lens (24) is an aspheric lens; preferably, each of said first lens (21), said second lens (22), said third lens (23) and said fourth lens (24) is made of resin material.

[0030] Please refer to Figure 2 and Figure 3 , in this embodiment, said reflective element (3) is a coated mirror. Said reflective element (3) is disposed on a side of said refracting element group (2) facing the image end, that is, located on a side of said fourth lens (24) away from said first lens (21). A reflective surface of said reflective element (3) is inclined, and said reflective surface forms predetermined angles with an incident optical axis and an exit optical axis respectively, so as to realize folding and reflection of the optical path at the reflective surface. According to different application scenarios, the angles between said reflective surface and the incident optical axis as well as the exit optical axis can be changed by adjusting the angle of said reflective element (3).

[0031] Based on the above structure: the ratio of the optical back focal length BFL to the total optical length TTL of said periscopic reflective lens satisfies 0.65 < BFL / TTL < 0.8, which enables said periscopic reflective lens to have a relatively long back focal length, provides necessary conditions for optical path折返, and can better correct aberrations. The ratio of the focal length f to the total optical length TTL of said periscopic reflective lens satisfies 0.8 < f / TTL < 1, which ensures that said periscopic reflective lens has a relatively large focal length when the total length is relatively short, and realizes the function of periscopic telephoto. The entrance pupil diameter of said periscopic reflective lens is the ratio of the focal length f of said periscopic reflective lens to the aperture value FNO, and said entrance pupil diameter satisfies 4 mm < f / FNO < 5 mm, which enables the lens to achieve an extreme balance between volume and image quality. The absolute value of distortion of said periscopic reflective lens in the full field of view is less than 1.2%, so that said periscopic reflective lens has a good distortion correction effect.

[0032] In use, light enters from said stop (1), and said stop (1) functions to converge and smooth the light. Then the light enters said first lens (21), the light is first converged by the convex surface of said first lens (21), and then diverged by the concave surface of said first lens (21). Since said first lens (21) has positive optical power, said first lens (21) generally performs a converging function on light. The concavo-convex matching lens can make the deflection of light gentler, so spherical aberration and coma can be controlled efficiently.

[0033] The light then enters the second lens 22. The light is first converged by the convex surface of the second lens 22, and then diverged by its concave surface. Because the second lens 22 has negative optical power, it generally diverges the light. This negative optical power characteristic allows the second lens 22 to reduce field curvature. Simultaneously, the high refractive index and low Abbe number of the second lens 22, combined with the low refractive index and high Abbe number of the first lens 21, help to reduce chromatic aberration.

[0034] As light continues to enter the third lens 23, it is first diverged by the concave surface of the third lens 23, and then converged by the convex surface. Since the third lens 23 has positive optical power, it generally has a converging effect on the light. The third lens 23 corrects the optical path, making the light path smoother and thus reducing system aberrations.

[0035] Light enters the fourth lens 24, whose concave-convex surface shape, in conjunction with its positive optical power, compresses and collimates the light beam. It also eliminates residual aberrations left by the first lens 21, the second lens 22, and the third lens 23, ensuring excellent image quality when the light beam reaches the reflecting element 3. Furthermore, it works in synergy with the positive optical power of the first lens 21 and the third lens 23, while balancing the negative optical power of the second lens 22 to further enhance its positive optical power. Finally, the light beam strikes the reflecting element 3 and, through reflection, reaches the color filter 4.

[0036] In this embodiment, the MTF chart, field curvature and distortion test chart, lateral chromatic aberration test chart, longitudinal chromatic aberration test chart, and dot plot of the periscope reflective lens are respectively as follows: Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown.

[0037] from Figure 4 As can be seen, at 195 line pairs / mm, the MTF of the entire field of view is greater than 0.42; at 98 line pairs / mm, the MTF of the entire field of view is greater than 0.67; and the MTF of the center field of view is greater than 0.79, which is close to the diffraction limit of the system. The overall MTF is high, indicating that the lens has excellent optical performance.

[0038] from Figure 5 As can be seen, the field curvature range of different wavelengths under the full field of view of the lens is within ±0.05mm, indicating that the field curvature of the lens is small; the distortion of the full field of view of the lens is within ±1.2%, indicating that the lens distortion correction is good.

[0039] from Figure 6As can be seen, the lateral chromatic aberration offset of the lens is controlled within ±0.05mm, indicating that the lens can effectively correct lateral chromatic aberration.

[0040] from Figure 7 As can be seen, the vertical chromatic aberration of the lens is controlled within ±1µm, indicating that the lens can effectively correct chromatic aberration.

[0041] from Figure 8 As can be seen, the maximum value of the RMS radius under the entire field of view is very small, only 1.37um, which is close to the chip pixel size, and all kinds of aberrations are small, indicating that the system has excellent performance.

[0042] The specific design parameters for this embodiment are shown in Table 1 below:

[0043] It should be noted that L1, L2, L3, and L4 are the first lens 21, the second lens 22, the third lens 23, and the fourth lens 24, respectively.

[0044] The aspheric coefficient and cone radius K values ​​of this embodiment are shown in Table 2 below:

[0045] Wherein, S2 and S3 are the object plane and image plane of the first lens 21, S4 and S5 are the object plane and image plane of the second lens 22, S6 and S7 are the object plane and image plane of the third lens 23, and S8 and S9 are the object plane and image plane of the fourth lens 24.

[0046] The specific design parameters for this embodiment are shown in Table 3 below:

[0047] Example 2: The shape of this embodiment is as follows: Figure 9 As shown, the main difference from Embodiment 1 lies in the material, curvature, thickness, and surface shape of the lens; The main design parameters of this embodiment are shown in Table 4 below:

[0048] The aspheric coefficient and cone radius K values ​​of this embodiment are shown in Table 5 below:

[0049] The specific design parameters for this embodiment are shown in Table 6 below:

[0050] In this embodiment, the MTF chart, field curvature and distortion test chart, lateral chromatic aberration test chart, longitudinal chromatic aberration test chart, and dot plot of the periscope reflective lens are respectively as follows: Figure 10 , Figure 11 , Figure 12 , Figure 13 and Figure 14 As shown.

[0051] from Figure 10 As can be seen, at 195 line pairs / mm, the MTF of the entire field of view is greater than 0.35; at 98 line pairs / mm, the MTF of the entire field of view is greater than 0.63; and the MTF of the center field of view is greater than 0.77, which is close to the diffraction limit of the system. The overall MTF is high, indicating that the lens has excellent optical performance.

[0052] from Figure 11 As can be seen, the field curvature range of different wavelengths under the full field of view of the lens is within ±0.05mm, indicating that the field curvature of the lens is small; the distortion of the full field of view of the lens is within ±1%, indicating that the lens distortion correction is good.

[0053] from Figure 12 As can be seen, the lateral chromatic aberration offset of the lens is controlled within ±0.05mm, indicating that the lens can effectively correct lateral chromatic aberration.

[0054] from Figure 13 As can be seen, the vertical chromatic aberration of this lens is controlled within ±5um, indicating that the lens can effectively correct chromatic aberration.

[0055] from Figure 14 As can be seen, the maximum value of the RMS radius under the entire field of view is very small, only 1.58um, which is close to the chip pixel size, and all kinds of aberrations are small, indicating that the system has excellent performance.

[0056] Example 3: The shape of this embodiment is as follows: Figure 15 As shown, the main differences from Embodiment 1 are in the working F-number, lens curvature, thickness, and surface shape. The main design parameters of this embodiment are shown in Table 7 below:

[0057] The aspheric coefficient and cone radius K values ​​of this embodiment are shown in Table 8 below:

[0058] The specific design parameters for this embodiment are shown in Table 9 below:

[0059] from Figure 16As can be seen, at 195 line pairs / mm, the MTF of the entire field of view is greater than 0.38; at 98 line pairs / mm, the MTF of the entire field of view is greater than 0.65; and the MTF of the center field of view is greater than 0.8, which is close to the diffraction limit of the system. The overall MTF is high, indicating that the lens has excellent optical performance.

[0060] from Figure 17 As can be seen, the field curvature of different wavelengths under the full field of view of the lens is within ±0.06mm, indicating that the field curvature of the lens is small; the distortion of the full field of view of the lens is within ±1.2%, indicating that the distortion correction of the lens is good.

[0061] from Figure 18 As can be seen, the lateral chromatic aberration offset of the lens is controlled within ±0.05mm, indicating that the lens can effectively correct lateral chromatic aberration.

[0062] from Figure 19 As can be seen, the vertical chromatic aberration of this lens is controlled within ±1.5um, indicating that the lens can effectively correct chromatic aberration.

[0063] from Figure 20 As can be seen, the maximum value of the RMS radius under the entire field of view is very small, only 1.424um, which is close to the chip pixel size, and all kinds of aberrations are small, indicating that the system has excellent performance.

[0064] Compared with the periscope reflection lens in the prior art, the periscope reflection lens of the present invention has the following advantages: the front arrangement of the diaphragm can gently smooth the incident angle of the chief ray. On the one hand, it directly shortens the back focal length of the lens to reduce the total length of the system, which lays a foundation for the lightweight and thinning of mobile devices; on the other hand, it reduces the design pressure of the rear lens group, facilitates the adoption of thinner lenses, simplifies aberration correction, and improves the overall performance of the system. The four lenses cooperate according to specific functional division: the first positive power lens with low refractive index (≤1.60) and high Abbe number (≥30) (convex on the object side and concave on the image side) can reduce its own chromatic aberration; the second negative power lens with high refractive index (≥1.60) and low Abbe number (<30) (convex on the object side and concave on the image side) can accurately control spherical aberration and field curvature, and since the chromatic aberration introduced by the first lens is small, the total amount of chromatic aberration to be corrected in the subsequent process is greatly reduced; the third positive power lens (concave on the object side and convex on the image side) further smooths the light to reduce the system aberration; the fourth positive power meniscus lens (concave on the object side and convex on the image side) can balance the system power and eliminate residual aberration. Combined with a coated reflector, the optical path is turned efficiently, a long back focal length is obtained while meeting the requirements of image height and CRA, and the parameter design of 0.8<f / TTL<1 ensures that the lens can realize the telephoto function when the total length is relatively short. The parameter 0.65<BFL / TTL<0.8 ensures that the optical back focal length is long enough, which can better optimize aberration, reduce tolerance sensitivity, improve mass productivity and reliability, and can also accommodate key non-lens elements (such as filters, anti-shake mechanisms, etc.). Compared with the traditional right-angle prism solution, the combination of aspherical resin lens and coated reflector greatly reduces the cost and mass of the lens module, and finally achieves a balance of miniaturization, light weight, thinning, low cost and high resolution, which perfectly meets the telephoto photography requirements of mobile terminals such as smart phones. In summary, the present invention forms a catadioptric optical system through the refraction element group and the reflection element, which cooperate to achieve long focal length and high image quality in a limited space, and has better aberration correction capability and lower manufacturing cost compared with the prior art.

[0065] The above embodiments only describe the preferred embodiments of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. A periscope reflecting lens, comprising an aperture stop, a refractive element group, a reflective element, and a color filter arranged sequentially from the object end to the image end along the optical axis, characterized in that: The refractive element group comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object side to an image side along the optical axis direction; the first lens has positive optical power, an object side surface thereof is a convex surface and an image side surface thereof is a concave surface; the second lens has negative optical power, an object side surface thereof is a convex surface and an image side surface thereof is a concave surface; the third lens has positive optical power, an object side surface thereof is a concave surface and an image side surface thereof is a convex surface; the fourth lens has positive optical power, an object side surface thereof is a concave surface and an image side surface thereof is a convex surface; the reflecting element is arranged on a side of the refractive element group facing the image side, light is incident on the reflecting element along an incident optical axis, is refracted after passing through a reflecting surface of the reflecting element and exits to an imaging surface along an exit optical axis; the reflecting surface forms predetermined angles with the incident optical axis and the exit optical axis respectively; a refractive index of the first lens is smaller than a refractive index of the second lens.

2. The periscope reflecting lens as described in claim 1, characterized in that: A ratio of an optical back focal length BFL to a total optical length TTL of the periscopic reflection lens satisfies 0.65 < BFL / TTL < 0.

8.

3. The periscope reflecting lens as described in claim 1, characterized in that: A ratio of a focal length f to a total optical length TTL of the periscopic reflection lens satisfies 0.8 < f / TTL < 1.

4. The periscope reflecting lens as described in claim 1, characterized in that: An entrance pupil diameter of the periscopic reflection lens = focal length f / aperture value FNO, and the entrance pupil diameter of the periscopic reflection lens satisfies 4 mm < f / FNO < 5 mm.

5. The periscope reflecting lens as described in claim 1, characterized in that: An absolute value of distortion of the periscopic reflection lens is less than 1.2% within the full field of view.

6. The periscope reflecting lens as described in claim 1, characterized in that: A clear semi-aperture DM1 of the first lens and a clear semi-aperture DM4 of the fourth lens satisfy 1 < DM1 / DM4 < 1.25 so as to make the light trend gentle.

7. The periscope reflecting lens as described in claim 1, characterized in that: Refractive indexes of the first lens, the third lens and the fourth lens are all ≤ 1.60, and a refractive index of the second lens is ≥ 1.

60.

8. The periscope reflecting lens as described in claim 1, characterized in that: Abbe numbers of the first lens, the third lens and the fourth lens are greater than or equal to 30, and an Abbe number of the second lens is less than 30.

9. The periscope reflecting lens as described in claim 1, characterized in that: The first lens, the second lens, the third lens and the fourth lens are all aspheric lenses, and the reflecting element is a coated reflecting mirror.

10. The periscope reflecting lens as described in claim 9, characterized in that: The first lens, the second lens, the third lens and the fourth lens are all made of resin material.

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