Telephoto lens and unmanned aerial vehicle

Abstract

The utility model provides a telephoto lens and an unmanned aerial vehicle, the telephoto lens comprises at least four lenses which are sequentially arranged from an object side to an image side, at least one of the at least four lenses is a super lens, and the rest lenses are refractors; the at least four lenses are arranged such that the telephoto lens satisfies: f / EPDlt; 6, 6.0, (43.27 / IMGH) * fgt; 180, and f is the effective focal length of the telephoto lens; the EPD is the entrance pupil aperture of the telephoto lens; iMGH is the imaging height of the telephoto lens; meanwhile, imaging quality such as chromatic aberration is improved, light weight and miniaturization of the telephoto lens can be promoted, and the telephoto lens is suitable for application scenes of unmanned aerial vehicles.

Description

Technical Field

[0001] The utility model relates to the field of optical telephoto imaging, in particular to a telephoto lens and a drone comprising the telephoto lens. Background Art

[0002] In recent years, the drone industry has developed rapidly, and its application scenarios have become more and more diverse. Drones have gradually penetrated into various application fields, from industrial and agricultural monitoring, logistics, traffic monitoring to surveying and mapping, tourism and real estate. In these applications, there are increasing requirements for long-distance shooting clarity, or clear magnification of parts of objects photographed at a distance. To meet this function, it is necessary to equip the drone with at least one telephoto lens.

[0003] A telephoto lens is a lens with a focal length greater than a standard lens (generally, the focal length of a standard lens is 50mm). A telephoto lens allows the photographer to shoot from a distance without having to get too close to the subject. Traditional refractive lens-type telephoto lenses usually have a large number of lenses (lenses) to meet the characteristics of long focal length and large aperture. The total length of the telephoto lens is relatively large, which leads to a complex structure and difficult assembly process on the one hand, and a large size and weight on the other hand. For drones, especially in the consumer field, the size and weight of the telephoto lens have a great impact on the internal structure design and endurance of the drone. Utility Model Content

[0004] The utility model aims to provide a telephoto lens which can reduce the number of lenses and the size of a lens group and has good telephoto imaging quality, and a drone comprising the telephoto lens.

[0005] In order to achieve the above-mentioned utility model purpose, the utility model adopts the following technical scheme: a telephoto lens,

[0006] The telephoto lens comprises at least four lenses arranged in sequence from the object side to the image side, at least one of the at least four lenses is a metalens, and the remaining lenses are refractive lenses;

[0007] The at least four lenses are arranged so that the telephoto lens satisfies: f / EPD<6.0, (43.27 / IMGH)*f>180, wherein f is the effective focal length of the telephoto lens; EPD is the entrance pupil diameter of the telephoto lens; and IMGH is the imaging height of the telephoto lens.

[0008] As a further improved technical solution of the utility model, the remaining lenses include at least two refractive lenses, and the absolute value of the refractive index difference between any two of the at least two refractive lenses is between 0.01 and 0.6.

[0009] As a further improved technical solution of the present utility model, the Abbe number V of each of the refractive lenses satisfies: 1 < V < 70.

[0010] As a further improved technical solution of the present utility model, each of the metalenses satisfies: 10 < |f M / f| < 190, where f M is the focal length of any one of the metalenses.

[0011] As a further improved technical solution of the present utility model, each of the metalenses satisfies: 2 < Δφ / R M | < 20, where Δφ is the maximum phase difference of the phase provided by the metalens at a single wavelength, and R M is the optical effective radius of the metalens.

[0012] As a further improved technical solution of the present utility model, the at least four lenses are arranged such that the telephoto lens satisfies: 0.7 < TTL / f < 1, where TTL is the total lens length of the telephoto lens.

[0013] As a further improved technical solution of the present utility model, the at least four lenses are arranged such that the telephoto lens satisfies: 50 < f*IMGH / N < 90, where N is the number of lenses in the telephoto lens.

[0014] As a further improved technical solution of the present utility model, the thickness of the metalens is 0.3 mm to 1.0 mm.

[0015] As a further improved technical solution of the present utility model, the metalens includes a base layer and at least one nanostructure layer provided on the base layer, and each of the nanostructure layers is a periodically arranged structure that is polarization-insensitive.

[0016] To achieve the purpose of the present utility model, the present utility model also provides a drone, and the drone includes the above-mentioned telephoto lens.

[0017] The beneficial effects of the present utility model are as follows: For the telephoto lens in the present utility model, on the one hand, the combination of the refractive lens and the metalens is adopted, so that the chromatic dispersion of the system is more easily compensated, and at the same time, the imaging quality such as chromatic aberration is improved, which can promote the light weight and miniaturization of the telephoto lens and is suitable for the drone application scenario; on the other hand, the at least four lenses are arranged such that the telephoto lens satisfies: f / EPD < 6.0, (43.27 / IMGH)*f > 180, so that the light transmission amount of the telephoto lens is as large as possible, enabling the drone to have a strong photosensitive ability in a low-light environment when using the telephoto lens to take pictures, and making the magnification of the telephoto lens larger when shooting distant objects, and being able to locally magnify and看清 the characteristics of distant objects while sacrificing the field of view size, so that the telephoto lens can meet the optical characteristics of the telephoto demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic cross-sectional view of a telephoto lens in the first embodiment of the present utility model along the optical axis;

[0019] Figure 2 yes Figure 1 Distortion curve of the telephoto lens in;

[0020] Figure 3 yes Figure 1 Astigmatism curve of the telephoto lens in;

[0021] Figure 4 yes Figure 1 The magnification chromatic aberration curve of the telephoto lens in;

[0022] Figure 5 yes Figure 1 Axial chromatic aberration curve of the telephoto lens in;

[0023] Figure 6 yes Figure 1 Phase distribution diagram of the metalens in the telephoto lens;

[0024] Figure 7 yes Figure 1 The mtf curves of each field of view of the telephoto lens vary with frequency;

[0025] Figure 8 is a schematic cross-sectional view of a telephoto lens in a second embodiment of the present invention along the optical axis;

[0026] Fig. 9 yes Figure 8 Distortion curve of the telephoto lens in;

[0027] Fig.10 yes Figure 8 Astigmatism curve of the telephoto lens in;

[0028] Fig.11 yes Figure 8 The magnification chromatic aberration curve of the telephoto lens in;

[0029] Fig.12 yes Figure 8 Axial chromatic aberration curve of the telephoto lens in;

[0030] Fig.13 yes Figure 8 Phase distribution diagram of the metalens in the telephoto lens;

[0031] Fig.14 yes Figure 8 The mtf curves of each field of view of the telephoto lens vary with frequency;

[0032] Fig.15 is a schematic cross-sectional view of a telephoto lens in a third embodiment of the present invention along the optical axis;

[0033] Fig.16 yes Fig.15 Distortion curve of the telephoto lens in;

[0034] Fig.17 yes Fig.15 Astigmatism curve of the telephoto lens in;

[0035] Fig.18 yes Fig.15 The magnification chromatic aberration curve of the telephoto lens in;

[0036] Fig.19 yes Fig.15 Axial chromatic aberration curve of the telephoto lens in;

[0037] Fig. 20 yes Fig.15 Phase distribution diagram of the metalens in the telephoto lens;

[0038] Fig.21 yes Fig.15 The mtf curves of each field of view of the telephoto lens vary with frequency;

[0039] Fig. 22 is a schematic cross-sectional view of a telephoto lens in a fourth embodiment of the present invention along the optical axis;

[0040] Fig.23 yes Fig. 22 Distortion curve of the telephoto lens in;

[0041] Fig.24 yes Fig. 22 Astigmatism curve of the telephoto lens in;

[0042] Fig.25 yes Fig. 22 The magnification chromatic aberration curve of the telephoto lens in;

[0043] Fig.26 yes Fig. 22 Axial chromatic aberration curve of the telephoto lens in;

[0044] Fig. 27 yes Fig. 22 Phase distribution diagram of the metalens in the telephoto lens;

[0045] Fig.28 yes Fig. 22 The mtf curves of each field of view of the telephoto lens vary with frequency;

[0046] Fig.29 is a schematic cross-sectional view of a telephoto lens in a fifth embodiment of the present invention along the optical axis;

[0047] Fig.30 yes Fig.29 Distortion curve of the telephoto lens in;

[0048] Fig.31 yes Fig.29 Astigmatism curve of the telephoto lens in;

[0049] Fig.32 yes Fig.29 The magnification chromatic aberration curve of the telephoto lens in;

[0050] Fig.33 yes Fig.29 Axial chromatic aberration curve of the telephoto lens in;

[0051] Fig.34 yes Fig.29 Phase distribution diagram of the metalens in the telephoto lens;

[0052] Fig.35 yes Fig.29 The mtf curve of each field of view of the telephoto lens changes with frequency. DETAILED DESCRIPTION

[0053] The following will describe the present invention in detail in conjunction with the embodiments shown in the accompanying drawings. Figures 1 to 35 It is shown as a preferred embodiment of the present invention. However, it should be noted that these embodiments are not limitations of the present invention, and any functional or structural equivalent transformation or substitution made by a person skilled in the art based on these embodiments shall fall within the protection scope of the present invention.

[0054] It should be noted that Figure 7 , Fig.14 , Fig.21 , Fig.28 , Fig.35 In the graph of the change of mtf of each field of view with frequency, different colors represent the fields of view at different incident angles, and the dotted line and solid line of the same color represent the meridian and sagittal directions respectively.

[0055] It should be understood that terms such as “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0056] Furthermore, it should be understood that although the terms first, second, third, etc. may be used in this article to describe various elements or structures, these described objects should not be limited by the above terms. The above terms are only used to distinguish these described objects from each other.

[0057] Please refer to Figure 1As shown, the utility model provides a telephoto lens and a drone having the telephoto lens. Of course, it can be understood that the telephoto lens in the utility model is not limited to drones, but can also be applied to other electronic devices with telephoto requirements, such as mobile phones.

[0058] The telephoto lens includes at least four lenses arranged in sequence from the object side to the image side, at least one of the at least four lenses is a metalens, and the remaining lenses are refractive lenses. On the one hand, the dispersion difference between the metalens and the refractive lens is relatively large. The refractive index of the refractive lens depends on the material itself, and its Abbe number is positive, while the Abbe number of diffractive optical elements such as metalens is always negative, and its refractive index for short wavelengths is smaller than that for long wavelengths, which is exactly the opposite of the refractive lens. Therefore, in the design of the telephoto lens of the utility model, the focal length of each group of the metalens and the refractive lens can be adjusted to meet the achromatic condition and achieve good imaging quality. Compared with the existing refractive elements that require a large number of lens groups for compensation, it is much simpler and is also conducive to the achromatic design of the separated design. The dispersion of the telephoto lens is easier to compensate, improving the imaging quality such as chromatic aberration; on the other hand, the superlens is an optical device composed of sub-wavelength nanounit structures arranged in a certain order. The wavefront can be arbitrarily controlled by changing the size of the nanounit structure or modulating the array arrangement. It has a high degree of design freedom and realizes the function of a traditional refractive lens or a refractive lens group. Compared with the refractive lens itself, the superlens is thinner and lighter. On the basis of reducing the number of lenses of the telephoto lens, the size of the telephoto lens is further reduced, promoting the lightweight and miniaturization of the telephoto lens, and is suitable for drone application scenarios.

[0059] It should be noted that, in some cases, a superlens can also be considered as a form of a refractive lens, but the refractive lens in the present invention does not include a superlens, that is, the refractive lens in the present invention is a non-superlens.

[0060] Further, the at least four lenses are arranged such that the telephoto lens satisfies: f / EPD < 6.0, (43.27 / IMGH) * f > 180, where f is the effective focal length of the telephoto lens; EPD is the entrance pupil diameter of the telephoto lens; and IMGH is the imaging height of the telephoto lens. In the present invention, the ratio between f and EPD, i.e., the F-number, represents the aperture of the telephoto lens, i.e., the light passing amount. By controlling f / EPD < 6.0, the light passing amount of the telephoto lens is made as large as possible, so that the drone can have a strong photosensitive ability even in a low-light environment when using the telephoto lens for shooting. At the same time, under the imaging target surface designed for the telephoto lens, by controlling (43.27 / IMGH) * f > 180, that is, controlling the equivalent focal length of the telephoto lens to be greater than 180, the magnification of the telephoto lens is larger when shooting distant objects, and the characteristics of distant objects can be locally magnified and clearly seen at the expense of the field of view. At the same time, the larger the IMGH imaging height, the higher the corresponding number of chip pixels can be, and the clearer the imaging is, so that the telephoto lens can meet the optical characteristics of the telephoto requirement.

[0061] Further, the at least four lenses are arranged such that the telephoto lens satisfies: 0.7 < TTL / f < 1, where TTL is the total length of the telephoto lens, that is, the distance from the surface of the first lens near the object side facing the object side to the image plane, or more specifically, TTL is the distance from the intersection point of the surface of the first lens near the object side facing the object side and the optical axis to the focus of the telephoto lens. It is possible to make the effective focal length as large as possible under the condition of controlling the total length of the lens to be smaller. By setting TTL / f greater than 0.7, it is avoided that the modulation ability of each lens to light is weakened due to the too small total length of the lens, resulting in insufficient imaging resolution of the telephoto lens; by setting TTL / f less than 1, the telephoto lens can have the advantage of miniaturization while achieving telephoto, so that the telephoto lens is suitable for drones.

[0062] Further, the at least four lenses are arranged such that the telephoto lens satisfies: 50 < f * IMGH / N < 90, where N is the number of lenses in the telephoto lens. Thus, the telephoto lens in the present invention adopts an optical system in the form of a hybrid of refractive lenses and meta-lenses, so that a larger imaging target surface and effective focal length can be achieved for the telephoto lens with fewer lenses.

[0063] Specifically, the object-side surface and the image-side surface of the refractive lens include aspherical surfaces or spherical surfaces. The expression of the aspherical surface is: where z is the surface sag parallel to the optical axis of the telephoto lens, c is the curvature of the center point of the aspherical surface (1 / R), k is the conic constant, that is, the conic coefficient, and A to G respectively correspond to the high-order coefficients.

[0064] Further, in a specific embodiment, the clear aperture of the telephoto lens is designed to be more than 7 mm, that is, the clear aperture is relatively large, so that the resolution and light collection ability of the telephoto lens are better.

[0065] Further, the Abbe number V of each of the refractive lenses satisfies: 1 < V < 70. The remaining lenses include at least two refractive lenses, that is, the telephoto lens includes at least two refractive lenses, and the absolute value of the refractive index difference between any two of the at least two refractive lenses is between 0.01 and 0.6. By selecting suitable materials to prepare the refractive lenses, that is, making the Abbe number V and the refractive index of the refractive lenses meet the above requirements, the refractive lenses can be combined with the modulation ability of the metasurface for each wavelength, which is relatively more conducive to compensating for axial chromatic aberration and magnification chromatic aberration.

[0066] Further, each of the metasurfaces satisfies: 10 < |f M / f| < 190, where f M is the focal length of any one of the metasurfaces. Since the clear aperture of the telephoto lens in the present invention is relatively large, on the one hand, in the design of the telephoto lens, it is controlled that the focal length of the metasurface is greater than the effective focal length of the telephoto lens and the ratio is greater than 10, that is, the optical power is small, which avoids the large chromatic dispersion caused by the metasurface providing too large optical power to the optical system of the telephoto lens, and is also conducive to the nanostructures in the metasurface to match the required target phase; on the other hand, setting an upper limit of 190 for the ratio of f M / f enables the metasurface to have a certain optical power to complete the ray modulation of each field of view.

[0067] Further, each of the metasurfaces satisfies: 2 < |Δφ / R M | < 20, where Δφ is the maximum phase difference of the phase provided by the metasurface at a single wavelength, and R M is the optical effective radius of the metasurface. It is known that at a single wavelength, the phases provided at different positions of the metasurface are generally different. By restricting the relationship between the maximum phase difference of the metasurface and the optical effective radius of the optical system of the telephoto lens, the metasurface has an excellent phase matching effect, can give full play to the optical performance of the metasurface more fully, and can effectively reduce the processing difficulty of the metasurface and increase the usability of the metasurface.

[0068] Specifically, the thickness of the metasurface is 0.3 mm to 1.0 mm. It should be noted that the thickness of any one of the metasurfaces refers to the maximum dimension of the metasurface in the optical axis direction. When the thickness of any one of the metasurfaces meets the above requirements, it is possible to increase the adjustment space of the air gap between the lenses within the limited total lens length TTL, so that the parameter freedom of the entire telephoto lens is higher.

[0069] Furthermore, each of the super lenses comprises a base layer and at least one nanostructure layer disposed on the base layer, wherein the at least one nanostructure layer and the base layer are stacked, and each of the nanostructure layers is a polarization-insensitive periodically arranged structure, which is beneficial to the image quality and energy efficiency of imaging in the visible light band.

[0070] Specifically, the phase of the metalens is set to meet one of the following conditions:

[0071]

[0072] Wherein, r is the distance from the center of the superlens to any nanostructure; λ is the operating wavelength of the superlens; is any phase related to the operating wavelength of the metalens; M is the focal length of the metalens; a i Real coefficients.

[0073] Furthermore, the telephoto lens also includes a filter between the lens on the image side and the image plane.

[0074] The present invention does not limit the specific quantity ratio, specific position, etc. of the metalens and the refractive lens in the telephoto lens. It is known that the metalens and the refractive lens in the telephoto lens only need to be arranged so that the telephoto lens can meet the above-mentioned conditions.

[0075] Combination Figure 1 to Figure 7 As shown, it is a telephoto lens in the first embodiment of the utility model, and the telephoto lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a filter 10 arranged in sequence from the object side to the image side, wherein the first lens 1 is a metalens, the second lens 2, the third lens 3, and the fourth lens 4 are all refractive lenses, the second lens has a positive focal power, and the fourth lens has a negative focal power. Specifically, the parameters of the telephoto lens in this embodiment are shown in Tables 1 to 3 below,

[0076] Table 1

[0077] Parameter Type Numeric Working band 400-700nm F-number 5.7 Effective focal length f 41mm Field of view 11.4° Holographic High IMGH 8mm System length TTL 37.5mm

[0078] Table 2

[0079] Face number Surface type Radius of curvature thickness Material Cone coefficient OBJ Spherical endless endless STO Spherical endless 0.02 S1 Spherical endless 0.625 1.465,65.77 S2 Metasurface endless 0.04 S3 Aspheric 9.2674 2.432 1.456,90.9 0.0013 S4 Aspheric 25.9881 17.447 5.063 S5 Aspheric -17.1973 5.0 1.784,25.68 9.147 S6 Aspheric -10.0673 0.25 -0.887 S7 Aspheric -6.8318 2.143 1.575,32.23 -3.848 S8 Aspheric -22.9534 0.259 -53.263 S9 Spherical endless 0.21 1.517,64.16 S10 Spherical endless 9.092 S11 Spherical endless

[0080] Table 3

[0081]

[0082]

[0083] Among them, in the above Table 2, S1 and S2 are respectively the object side surface and the image side surface of the super lens (first lens) 1, the image side surface of the first lens 1 has a nanostructure layer, S3 and S4 are the object side surface and the image side surface of the second lens 2, S5 and S6 are the object side surface and the image side surface of the third lens 3, S7 and S8 are the object side surface and the image side surface of the fourth lens 4, S9 and S10 are the object side surface and the image side surface of the filter 10, and S11 is the image surface IS.

[0084] The object side and image side of the three refractive lenses in this embodiment are all aspherical surfaces. As shown in Table 3 above, AG are the coefficients of the 4th, 6th, and 16th order terms of the aspherical surfaces, and the expression used for the aspherical surface is: In the formula, z is the surface vector height parallel to the optical axis of the telephoto lens, c is the center point curvature of the aspheric surface (1 / R), k is the quadratic surface constant (cone coefficient), and A to G correspond to high-order coefficients respectively.

[0085] Specifically, in this embodiment, f / EPD=5.7 is controlled to maximize the light transmission of the telephoto lens under the condition of using 4 lenses, so that the telephoto lens can have a strong light sensitivity even in a dark environment when shooting. 43.27 / IMGH*f=221.8 is controlled, which is equivalent to the equivalent focal length of the telephoto lens being 221.8mm, that is, the telephoto lens has a greater magnification when shooting distant objects, and can partially magnify the features of distant objects. At the same time, the larger the IMGH imaging height, the higher the number of pixels of the imaging chip. Control |f M / f|=27.3, which prevents the metalens from providing too much optical power to the telephoto lens and causing large dispersion. It is also beneficial for the nanostructure in the metalens to match the required target phase, and at the same time use the target phase to modulate the light in each field of view to correct the high-order aberrations of the telephoto lens. Constraint Δφ / R M |=3.04, by controlling the ratio between the maximum phase difference of the metalens and the optical effective radius of the telephoto lens, the 2pi phase period of the metalens per unit length is made to match the matching effect of the nanostructure on its target phase, and the optical performance of the metalens can be more fully exerted when the phase gradient at the edge of the metalens is small. Constraining TTL / f=0.91, the effective focal length is made as large as possible under the condition that the total length TTL of the control system is small, and the size of the telephoto lens is miniaturized. The size and volume of the telephoto lens are crucial in drones. Controlling f*IMGH / N=82, a larger imaging target surface and effective focal length of the system are achieved by adopting a hybrid form of 3 refractive lenses and 1 metalens.

[0086] Combination Figure 2 to Figure 5 as well as Figure 7 As shown, it can be seen that the telephoto lens in this embodiment has a lower optical distortion value, a smaller astigmatism, a smaller chromatic aberration, and has better imaging quality.

[0087] Combination Figures 8 to 14 As shown, it is a telephoto lens in the second embodiment of the utility model, and the telephoto lens includes a first lens 1a, a second lens 2a, a third lens 3a, a fourth lens 4a, a fifth lens 5a, and a filter 10 arranged in sequence from the object side to the image side, wherein the third lens 3a is a super lens, the first lens 1a, the second lens 2a, the fourth lens 4a, and the fifth lens 5a are all refractive lenses, the object side surface of the second lens 2a is a convex surface, and the optical power of the fifth lens 5a is negative. Specifically, the parameters of the telephoto lens in this embodiment are shown in the following Tables 4 to 6,

[0088] Table 4

[0089] Parameter Type Numeric Working band 400-700nm F-number 5.18 Effective focal length f 49mm Field of view 10° Holographic High IMGH 8.74mm System length TTL 37mm

[0090] Table 5

[0091]

[0092]

[0093] Table 6

[0094]

[0095] Among them, in the above Table 5, S1 and S2 are respectively the object side surface and the image side surface of the first lens 1a, S3 and S4 are respectively the object side surface and the image side surface of the second lens 2a, S5 and S6 are respectively the object side surface and the image side surface of the super lens (third lens) 3a, wherein the object side surface of the super lens has a nanostructure layer, S7 and S8 are respectively the object side surface and the image side surface of the fourth lens 4a, S9 and S10 are respectively the object side surface and the image side surface of the fifth lens 5a, S11-S12 are the object side surface and the image side surface of the filter 10, and S13 is the image surface IS.

[0096] The object side and image side of the four refractive lenses in this embodiment are all aspherical, but low-order aspherical coefficients are used to facilitate processing. AG are the coefficients of the 4th, 6th and 16th order aspherical terms, respectively. The expression used for the aspherical is: In the formula, z is the surface vector height parallel to the optical axis of the telephoto lens provided in the embodiment of the present application, c is the center point curvature of the aspheric surface (1 / R), k is the quadratic surface constant (cone coefficient), and A~G correspond to high-order coefficients respectively.

[0097] Specifically, in this embodiment, f / EPD=5.18 is controlled to make the light throughput of the system as large as possible under the condition of using 5 lenses, so that the lens can have a strong photosensitivity even in a dark environment when shooting. Control 43.27 / IMGH*f=242.6, which is equivalent to the equivalent focal length of the telephoto lens being 242.6mm, that is, the telephoto lens has a greater magnification when shooting distant objects, and can partially magnify the features of distant objects. At the same time, the larger the IMGH imaging height, the higher the number of pixels of the imaging chip. Control |fM / f|=31.3. In the design, the focal length of the metalens is controlled to avoid the metalens providing excessive optical focal length to the telephoto lens, which causes large dispersion. It is also beneficial for the nanostructure in the metalens to match the required target phase, and at the same time, the target phase is used to modulate the light of each field of view to achieve the purpose of correcting the higher-order aberrations of the system. Constrain Δφ / R M |=2.69, by controlling the ratio between the maximum phase difference of the metalens and the optical effective radius of the telephoto lens, the 2pi phase period of the metalens per unit length is made to match the matching effect of the micro-nano structure on its target phase, and the optical performance of the metalens can be more fully exerted when the phase gradient at the edge of the lens is small. Constraining TTL / f=0.76, the effective focal length is made as large as possible under the condition that the total length TTL of the control system is small, and the system size is miniaturized. Controlling f*IMGH / N=85.7, a larger imaging target surface and effective focal length of the system are achieved by adopting a hybrid form of 4 refractive lenses and 1 metalens.

[0098] Combination Figures 9 to 12 as well as Fig.14 As shown, it can be seen that the telephoto lens in this embodiment has a lower optical distortion value, a smaller astigmatism, a smaller chromatic aberration, and has better imaging quality.

[0099] Combination Figure 15 to Figure 21 As shown, it is a telephoto lens in the third embodiment of the utility model, and the telephoto lens includes a first lens 1b, a second lens 2b, a third lens 3b, a fourth lens 4b, a fifth lens 5b, a sixth lens 6b, and a filter 10, which are arranged in sequence from the object side to the image side, wherein the fourth lens 4b is a super lens, the first lens 1b, the second lens 2b, the third lens 3b, the fifth lens 5b, and the sixth lens 6b are all refractive lenses, and the object side surface of the first lens 1b is a convex surface, and the optical power is positive. Specifically, the parameters of the telephoto lens in this embodiment are shown in the following Tables 7 to 9:

[0100] Table 7

[0101] Parameter Type Numeric Working band 400-700nm F-number 4.18 Effective focal length f 52.9mm Field of view 9.2° Holographic High IMGH 8.34mm System length TTL 38mm

[0102] Table 8

[0103]

[0104]

[0105] Table 9

[0106]

[0107] Among them, in the above Table 8, S1 and S2 are respectively the object side surface and the image side surface of the first lens 1b, S3 and S4 are respectively the object side surface and the image side surface of the second lens 2b, S5 and S6 are respectively the object side surface and the image side surface of the third lens 3b, S7 and S8 are respectively the object side surface and the image side surface of the super lens (fourth lens) 4b, wherein the image side surface of the super lens has a nanostructure layer, S9 and S10 are respectively the object side surface and the image side surface of the fifth lens 5b, S11 and S12 are respectively the object side surface and the image side surface of the sixth lens 6b, S13-S14 are the object side surface and the image side surface of the filter 10, and S15 is the image surface IS.

[0108] The object side and image side of the five refractive lenses in this embodiment are all aspherical surfaces. AG are the coefficients of the 4th, 6th, and 16th order terms of the aspherical surfaces. The expression used for the aspherical surface is: In the formula, z is the surface vector height parallel to the optical axis of the telephoto lens provided in the embodiment of the present application, c is the center point curvature of the aspheric surface (1 / R), k is the quadratic surface constant (cone coefficient), and A~G correspond to high-order coefficients respectively.

[0109] Specifically, in this embodiment, f / EPD=4.18 is controlled to maintain the system's aperture at a large level under the condition of using 6 lenses. Increasing the number of lenses can better correct aberrations, and can also make the lens have strong photosensitivity in dark environments, thereby improving the signal-to-noise ratio of the telephoto lens. Controlling 43.27 / IMGH*f=274.5 is equivalent to an equivalent focal length of 274.5mm, that is, the lens has a greater magnification when shooting distant objects, and can partially magnify the features of distant objects. At the same time, the larger the IMGH imaging height, the higher the number of pixels of the imaging chip. Controlling |fM / f|=184.1, controlling the focal length of the superlens to avoid the superlens providing the telephoto lens with too much optical focal length and causing large dispersion, is also beneficial for the nanostructure in the superlens to match the required target phase, and at the same time, using the target phase to modulate each field of view to achieve the purpose of correcting the system's higher-order aberrations. Constraining Δφ / R M|=2.33, by controlling the ratio between the maximum phase difference of the metalens and the optical effective radius of the telephoto lens, the 2pi phase period of the metalens per unit length is made to match the matching effect of the micro-nanostructure on its target phase, and the optical performance of the metalens can be more fully exerted when the phase gradient at the edge of the lens is small. Constrain TTL / f=0.72, under the condition of a small total length TTL of the control system, the effective focal length is made as large as possible, and the size of the telephoto lens is miniaturized. The size and volume of the telephoto lens are crucial in drones. Control f*IMGH / N=73.5, and achieve a larger imaging target surface and effective focal length of the system by adopting a hybrid form of 5 refractive lenses and 1 metalens.

[0110] Combination Figure 16 to Figure 19 as well as Fig.21 As shown, it can be seen that the telephoto lens in this embodiment has a lower optical distortion value, a smaller astigmatism, a smaller chromatic aberration, and has better imaging quality.

[0111] Combination Figure 22 to Figure 28 As shown, it is a telephoto lens in the fourth embodiment of the utility model, and the telephoto lens includes a first lens 1c, a second lens 2c, a third lens 3c, a fourth lens 4c, a fifth lens 5c, a sixth lens 6c, a seventh lens 7c, an eighth lens 8c, and a filter 10, which are arranged in sequence from the object side to the image side, wherein the seventh lens 7c is a super lens, and the remaining lenses are all refractive lenses, the object side surface of the first lens 1c is a convex surface, and the optical focal length is positive, and the optical focal length of the eighth lens 8c is negative. Specifically, the parameters of the telephoto lens in this embodiment are shown in the following Tables 10 to 12:

[0112] Table 10

[0113] Parameter Type Numeric Working band 400-700nm F-number 4.08 Effective focal length f 52.9mm Field of view 8.8° Holographic High IMGH 8.24mm System length TTL 37.3mm

[0114] Table 11

[0115]

[0116] Table 12

[0117]

[0118] Among them, in the above Table 11, S1 and S2 are respectively the object side surface and the image side surface of the first lens 1c, S3 and S4 are respectively the object side surface and the image side surface of the second lens 2c, S5 and S6 are respectively the object side surface and the image side surface of the third lens 3c, S7 and S8 are respectively the object side surface and the image side surface of the fourth lens 4c, S9 and S10 are respectively the object side surface and the image side surface of the fifth lens 5c, S11 and S12 are respectively the object side surface and the image side surface of the sixth lens 6c, S13 and S14 are respectively the object side surface and the image side surface of the super lens (seventh lens) 7c, wherein the object side surface of the super lens has a nanostructure layer, S15 and S16 are respectively the object side surface and the image side surface of the eighth lens 8c, S17-S18 are the object side surface and the image side surface of the filter 10, and S19 is the image surface IS.

[0119] The object side and image side of the seven refractive lenses in this embodiment are all aspherical surfaces, and AG are the coefficients of the 4th, 6th, and 16th order terms of the aspherical surfaces, respectively. The expression used for the aspherical surface is:

[0120] In the formula, z is the surface vector height parallel to the optical axis of the telephoto lens provided in this embodiment, c is the center point curvature of the aspheric surface (1 / R), k is the quadratic surface constant (cone coefficient), and A~G correspond to high-order coefficients respectively.

[0121] Specifically, in this embodiment, f / EPD=4.08 is controlled, and the aperture of the system is maintained at a large level under the condition of using 8 lenses. Due to the large aperture, the aberrations related to the system and the aperture increase a lot, such as spherical aberration, coma, etc. After increasing the number of lenses, the aberrations can be better corrected, and the lens can also have a strong photosensitivity in a dark environment, improving the signal-to-noise ratio of the telephoto lens. Controlling 43.27 / IMGH*f=277.8 is equivalent to the equivalent focal length of the lens being 277.8mm, that is, the telephoto lens has a larger magnification when shooting distant objects, and can partially magnify the features of distant objects. At the same time, the larger the IMGH imaging height, the higher the number of pixels of the imaging chip. Controlling |fM / f|=19.9, in the design, the focal length of the metalens is controlled to avoid the metalens providing excessive optical power to the telephoto lens, which brings about large dispersion, and is also conducive to the nanostructure in the metalens matching the required target phase, and at the same time, the target phase is used to modulate the light of each field of view to achieve the purpose of correcting the higher-order aberrations of the system. Constraint Δφ / R M|=8.38, by controlling the ratio between the maximum phase difference of the metalens and the optical effective radius of the optical system, the 2pi phase period of the metalens per unit length is made to match the matching effect of the micro-nanostructure on its target phase, and the metalens is made more suitable for mass production according to the periodic arrangement of the nanopillars. Constrain TTL / f=0.71, and make the effective focal length as large as possible under the condition of a small total length TTL of the control system, so as to achieve miniaturization of the telephoto lens size, which is crucial in drones. Control f*IMGH / N=54.5, and achieve a larger imaging target surface and effective focal length of the system by adopting a hybrid form of 7 refractive lenses and 1 metalens.

[0122] Combination Figure 23 to Figure 26 as well as Fig.28 As shown, it can be seen that the telephoto lens in this embodiment has a lower optical distortion value, a smaller astigmatism, a smaller chromatic aberration, and has better imaging quality.

[0123] Combination Figure 29 to Figure 35 As shown, it is a telephoto lens in the fifth embodiment of the utility model, which includes a first lens 1d, a second lens 2d, a third lens 3d, a fourth lens 4d, a fifth lens 5d, a sixth lens 6d, a seventh lens 7d, an eighth lens 8d, and a filter 10 arranged in sequence from the object side to the image side, wherein the eighth lens 8d is a super lens, and the remaining lenses are all refractive lenses, and the object side surface of the first lens 1d is a convex surface, and the optical power is positive. Specifically, the parameters of the telephoto lens in this embodiment are shown in the following Tables 13 to 15:

[0124] Table 13

[0125] Parameter Type Numeric Working band 400-700nm F-number 4.0 Effective focal length f 52.5mm Field of view 11.3° Holographic High IMGH 10.62mm System length TTL 38mm

[0126] Table 14

[0127] Face number Surface type Radius of curvature thickness Material Cone coefficient OBJ Spherical endless endless STO Spherical endless -1.1845 S1 Aspheric 20.7098 2.3942 1.456,90.9 1.897 S2 Aspheric -47.6000 0.0698 39.668 S3 Spherical -40.4078 0.584 1.834,37.29 S4 Spherical 40.5911 0.05 S5 Aspheric 8.3842 2.718 1.456,90.0 -1.012 S6 Aspheric 37.0448 0.07 -97.509 S7 Spherical 14.5368 1.0646 1.699,30.2 S8 Spherical 19.0853 7.3989 S9 Spherical -27.6746 0.575 1.904,31.32 S10 Spherical 8.2110 0.07 S11 Aspheric 6.9193 1.8177 1.785,25.68 -1.187 S12 Aspheric 500.9877 5.9984 99 S13 Aspheric -13.9867 0.575 1.508,61.18 7.108 S14 Aspheric 758.3792 0.7 -99 S15 Metasurface endless 0.625 1.465,65.77 S16 Spherical endless 5.7329 S17 Spherical endless 0.21 1.517,64.17 S18 Spherical endless 7.3361 S19 Spherical endless 0

[0128] Table 15

[0129]

[0130]

[0131] Among them, in the above Table 14, S1 and S2 are respectively the object side surface and the image side surface of the first lens 1d, S3 and S4 are respectively the object side surface and the image side surface of the second lens 2d, S5 and S6 are respectively the object side surface and the image side surface of the third lens 3d, S7 and S8 are respectively the object side surface and the image side surface of the fourth lens 4d, S9 and S10 are respectively the object side surface and the image side surface of the fifth lens 5d, S11 and S12 are respectively the object side surface and the image side surface of the sixth lens 6d, S13 and S14 are respectively the object side surface and the image side surface of the seventh lens 7d, S15 and S16 are respectively the object side surface and the image side surface of the super lens (eighth lens) 8d, wherein the object side surface of the super lens has a nanostructure layer, S17-S18 are the object side surface and the image side surface of the filter 10, and S19 is the image surface IS.

[0132] In this embodiment, the object side surface and image side surface of the first lens 1d, the third lens 3d, the sixth lens 6d, and the seventh lens 7d are all aspherical surfaces. AG are coefficients of the 4th, 6th, and 16th order terms of the aspherical surfaces, respectively. The expression used for the aspherical surface is: In the formula, z is the surface vector height parallel to the optical axis of the telephoto lens provided in this embodiment, c is the center point curvature of the aspheric surface (1 / R), k is the quadratic surface constant (cone coefficient), and A~G correspond to high-order coefficients respectively.

[0133] Specifically, in this embodiment, f / EPD=4.0 is controlled to maintain the system aperture at a relatively large level under the condition of using 8 lenses. Due to the large aperture, the aberrations related to the system and the aperture increase a lot, such as spherical aberration, coma, etc. After increasing the number of lenses, the aberrations can be better corrected, and the lens can also have a strong photosensitivity in a dark environment, improving the signal-to-noise ratio of the telephoto lens. Controlling 43.27 / IMGH*f=213.9 is equivalent to the equivalent focal length of the telephoto lens being 213.9mm, that is, the telephoto lens has a larger magnification when shooting distant objects, and can partially magnify the features of distant objects. At the same time, the IMGH imaging image height is 10.62mm, and the number of pixels of the imaging chip will be greatly increased. Control |fM / f|=16.1. In the design, the focal length of the metalens is controlled to avoid the metalens providing too much optical power to the telephoto lens, which will cause large dispersion. It is also beneficial for the nanostructure in the metalens to match the required target phase. At the same time, the target phase is used to modulate the light in each field of view to correct the high-order aberrations of the system. Constraint Δφ / R M|=2.78, by controlling the ratio between the maximum phase difference of the metalens and the optical effective radius of the telephoto lens, the 2pi phase period of the metalens per unit length is made to match the matching effect of the micro-nano structure on its target phase, and the optical performance of the metalens can be more fully exerted when the phase gradient at the edge of the lens is small. Constrain TTL / f=0.72, under the condition that the total length TTL of the control system is small, the effective focal length is made as large as possible to achieve miniaturization of the system size. The size and volume of the lens module are crucial in drones. Control f*IMGH / N=69.7. In this embodiment, a larger imaging target surface and effective focal length of the system are achieved by using a hybrid form of 7 refractive lenses and 1 metalens.

[0134] Combination Figure 30 to Figure 33 as well as Fig.35 As shown, it can be seen that the telephoto lens in this embodiment has a lower optical distortion value, a smaller astigmatism, a smaller chromatic aberration, and has better imaging quality.

[0135] Compared with the prior art, the telephoto lens in the utility model, on the one hand, adopts a combination of a refractive lens and a super lens, so that the dispersion of the system is easier to compensate, and at the same time improves the imaging quality such as chromatic aberration, which can promote the lightweight and miniaturization of the telephoto lens, and is suitable for drone application scenarios; on the other hand, at least four lenses are set to make the telephoto lens satisfy: f / EPD<6.0, (43.27 / IMGH)*f>180, so that the light transmittance of the telephoto lens is as large as possible, so that the drone can have a strong photosensitivity in a dark light environment when using the telephoto lens for shooting, and the telephoto lens has a larger magnification when shooting distant objects, and can partially magnify the features of distant objects while sacrificing the size of the field of view, so that the telephoto lens can meet the optical characteristics of telephoto requirements.

[0136] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0137] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the utility model. They are not intended to limit the protection scope of the utility model. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A telephoto lens, characterized in that: The telephoto lens includes at least four lenses arranged in sequence from the object side to the image side, at least one of the at least four lenses being a meta-lens, and the remaining lenses being refractive lenses; The at least four lenses are arranged such that the telephoto lens satisfies: f / EPD < 6.0, (43.27 / IMGH) * f > 180, where f is the effective focal length of the telephoto lens; EPD is the entrance pupil diameter of the telephoto lens; IMGH is the imaging image height of the telephoto lens.

2. The telephoto lens according to claim 1, wherein: The remaining lenses include at least two refractive lenses, and the absolute value of the refractive index difference between any two of the at least two refractive lenses is between 0.01 and 0.

6.

3. The telephoto lens according to claim 1, wherein: The Abbe number V of each of the refractive lenses satisfies: 1 < V < 70.

4. The telephoto lens according to claim 1, wherein: Each of the metalens satisfies: 10<|f M / f|<190, where f M is the focal length of any metalens.

5. The telephoto lens according to claim 1, wherein: Each of the metalenses satisfies: 2<Δφ / R M <20, where Δφ is the maximum phase difference provided by the metalens at a single wavelength, R M is the optical effective radius of the metalens.

6. The telephoto lens according to claim 1, wherein: The at least four lenses are arranged such that the telephoto lens satisfies: 0.7 < TTL / f < 1, where TTL is the total lens length of the telephoto lens.

7. The telephoto lens according to claim 1, wherein: The at least four lenses are arranged such that the telephoto lens satisfies: 50 < f * IMGH / N < 90, where N is the number of lenses in the telephoto lens.

8. The telephoto lens according to claim 1, wherein: The thickness of the meta-lens is 0.3 mm to 1.0 mm.

9. The telephoto lens according to claim 1, wherein: The meta-lens includes a base layer and at least one nano-structured layer provided on the base layer, and each nano-structured layer is a polarization-insensitive periodic arrangement structure.

10. A drone, characterized in that: The drone includes the telephoto lens according to any one of claims 1 to 9.

Images