An ultra-compact long-focus lens, a camera module and a terminal device

Abstract

The application discloses a folded super-hybrid long-focus lens, a camera module and a terminal device. The lens comprises a first lens, a second lens, a third lens and a prism arranged along an optical axis from an object plane to an image plane. The first lens is a spherical lens with positive focal power. The second lens is a super lens with positive focal power. The third lens is an aspherical lens with negative focal power. The second lens of the application provides positive focal power while hardly occupying additional axial space, effectively shortening the air gap between the first lens and the third lens. At the same time, the positive focal power of the first lens, the positive focal power of the second lens and the negative focal power of the third lens constitute a telephoto focal power distribution structure, so that the principal plane of the system can be moved forward, achieving long focal length while significantly compressing the distance from the object side of the first lens to the image plane. Finally, the volume is compact and the imaging performance is good. It has the advantages of simple structure, miniaturization, short total length, high image quality and low chromatic aberration.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a hybrid telephoto lens, camera module, and terminal device. Background Technology

[0002] As electronic devices evolve towards miniaturization and high performance, the demand for telephoto lenses is increasing, especially in portable devices such as mobile phones and drones, which place dual demands on miniaturization, lightweight design, and image quality in telephoto imaging. Traditional pure refractive telephoto lenses rely on a combination of multiple curved lenses to achieve long focal lengths, which results in drawbacks such as large size and heavy weight, making it difficult to adapt to the design requirements of portable devices. Furthermore, an excessive number of elements can lead to aberration accumulation, affecting image sharpness.

[0003] Metasurfaces are artificial materials composed of subwavelength-scale structural units that can precisely control the phase, amplitude, and propagation direction of light, providing new degrees of freedom for the design of optical systems. Compared with traditional optical materials, metasurfaces have complementary dispersion characteristics and have the potential to correct chromatic aberration. Hybrid optical systems that combine the advantages of traditional optical materials and metasurfaces have become an important technological direction for breaking through the performance limitations of traditional periscope lenses.

[0004] Therefore, how to combine metasurface technology to achieve miniaturized, thinner, and high-resolution telephoto lenses is a key issue that urgently needs to be addressed. Summary of the Invention

[0005] The purpose of this invention is to provide a hybrid telephoto lens, camera module, and terminal device, aiming to solve the problem of how to effectively apply metasurface technology to optical lenses to achieve miniaturized, thinner, and high-imaging telephoto lenses.

[0006] To solve the above-mentioned technical problems, the objective of this invention is achieved through the following technical solution: providing a hybrid telephoto lens, comprising a first lens, a second lens, a third lens, and a prism arranged along the optical axis from the object plane to the image plane; the first lens is a spherical lens, the second lens is a superlens, and the third lens is an aspherical lens; The first lens has positive optical power, and its object side is convex, and its image side is convex. The second lens has positive optical power and its image-side surface has a microstructure arrangement; The third lens has negative optical power, and its object side is convex, as is its image side.

[0007] Furthermore, the superconducting telephoto lens satisfies the following condition: TTL / MIC ≤ 4.08; where TTL represents the distance from the optical axis center of the first lens object side to the image plane, and MIC represents the maximum image circle size.

[0008] Furthermore, the superconducting telephoto lens satisfies: 4.0 ≤ EFL / L1 ≤ 6.27; where EFL represents the effective focal length; and L1 represents the distance from the object-side surface of the first lens to the object-side surface of the prism.

[0009] Furthermore, the hybrid telephoto lens also includes an aperture stop, which is located between the first lens and the second lens, or between the second lens and the third lens.

[0010] Furthermore, the first lens is made of glass, the second lens is made of plastic or glass, the third lens is made of plastic, and the prism is made of plastic or glass.

[0011] Furthermore, the prism is one of the following: flat glass, right-angle prism, roof prism, or cemented composite prism.

[0012] Furthermore, the superconducting telephoto lens also includes a filter located on the image side of the prism.

[0013] Furthermore, the prism satisfies n*L≤44.95mm, where n is the refractive index of the prism and L is the length of the prism.

[0014] Furthermore, the focal length f of the hybrid telephoto lens satisfies: f≥28mm.

[0015] Furthermore, the field of view (Fov) of the super-refractive telephoto lens satisfies: Fov ≥ 18°.

[0016] Furthermore, the aperture number F of the hybrid telephoto lens satisfies F≤3.5.

[0017] This invention also provides a camera module, including a telephoto lens with a folding-hyperfocal hybrid structure as described above.

[0018] This invention also provides a terminal device, including the camera module described above.

[0019] The beneficial effects of this invention are as follows: Since the second lens uses a planar substrate superlens, it provides positive optical power while occupying almost no additional axial space, effectively shortening the air gap between the first and third lenses. Simultaneously, the positive optical power of the first lens, the positive optical power of the second lens, and the negative optical power of the third lens constitute a telephoto optical power distribution structure, allowing the principal plane of the system to move forward, significantly compressing the distance from the object side of the first lens to the image plane while achieving a long focal length. Ultimately, this lens can provide good basic imaging performance while maintaining a compact size. It has the advantages of simple structure, miniaturization, short overall length, high image quality, and low chromatic aberration. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the superconducting telephoto lens provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the visible light MTF of the superconducting telephoto lens provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the visible light diffusion pattern of a telephoto lens with superconductivity and refractive index hybridization provided in Embodiment 1 of the present invention. Figure 4 The lateral chromatic aberration diagram of the super-refractive hybrid telephoto lens provided in Embodiment 1 of the present invention; Figure 5 This is a field curvature distortion diagram of a telephoto lens with a hybrid refractive and hyper-refractive power structure provided in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the structure of the superconducting telephoto lens provided in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram of the visible light MTF of the superconducting telephoto lens provided in Embodiment 2 of the present invention. Figure 8 This is a schematic diagram of the visible light diffusion pattern of the telephoto lens with superconductivity and refractive index hybrid technology provided in Embodiment 2 of the present invention. Figure 9 This is a chromatic aberration diagram of a telephoto lens with super-refractive hybrid structure provided in Embodiment 2 of the present invention; Figure 10 This is a field curvature distortion diagram of a telephoto lens with a hybrid refractive and hyper-refractive structure provided in Embodiment 2 of the present invention; Figure 11 This is a schematic diagram of the nanopillar arrangement of a metasurface lens provided in an embodiment of the present invention; Figure 12 This is a schematic diagram of the metasurface layer nanopillar structure of the metasurface lens provided in an embodiment of the present invention; Figure 13 A schematic diagram showing the relationship between the transmittance and phase of the metasurface lens nanopillar and the nanopillar diameter, as provided in an embodiment of the present invention. Figure 14 This is a schematic diagram of the metasurface layer structure of the metasurface lens provided in Embodiment 1 of the present invention; Figure 15 This is a schematic diagram of the metasurface layer structure of the metasurface lens provided in Embodiment 2 of the present invention.

[0022] Explanation of the markings in the image: 110, First lens; 120, Second lens; 130, Aperture stop; 140, Third lens; 150, Prism; 160, Filter; 200, Imaging plane. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] For ease of understanding, some of the technical terms involved in the embodiments of the present invention will be explained and described below.

[0025] The optical axis is the direction in which light rays travel through an optical system, with the principal ray serving as a reference for the central field of view. In other words, the optical axis is a ray that passes perpendicularly through the center of an ideal lens. When light rays parallel to the optical axis enter a convex lens, an ideal convex lens should cause all the light rays to converge at a single point behind the lens; this point is the focal point.

[0026] Focal length, also known as focal length, is a measure of the convergence or divergence of light in an optical system. It refers to the distance from the optical center of a lens to the focal point when a distant object is focused into a clear image on the focal plane. The optical center is the point on the lens where the direction of light propagation remains unchanged regardless of the direction of light passing through it. For fixed-focus lenses, the position of their optical center is fixed, therefore the focal length is fixed. For zoom lenses, changes in the optical center result in changes in the focal length, therefore the focal length can be adjusted.

[0027] The aperture is a device used to control the amount of light passing through the lens and entering the sensor inside the camera body; it is usually located inside the lens.

[0028] The aperture f-number is a relative value derived from the lens's focal length divided by its light-gathering diameter. A smaller f-number allows more light to enter the lens within the same time frame. A larger f-number results in a shallower depth of field, blurring the background and creating an effect similar to a telephoto lens.

[0029] Optical power is equal to the difference between the image-side convergence and the object-side convergence of the light beam. It characterizes the ability of an optical system to deflect light rays. When the refractive index of air is approximately assumed to be 1, optical power is generally expressed as the reciprocal of the image-side focal length.

[0030] Optical power characterizes the ability of an optical system to refract an incident parallel beam of light. The higher the optical power value, the more pronounced the refraction of the parallel beam. When the optical power is greater than zero, the refraction is converging; when the optical power is less than zero, the refraction is diverging; when the optical power is equal to zero, it is plane refraction, in which case the axial parallel beam remains axially parallel after refraction, and no refraction occurs.

[0031] Total track length (TTL) refers to the total length from the lens head to the imaging plane, and is the main factor that determines the camera height.

[0032] The Abbe number, also known as the dispersion coefficient, is the ratio of the difference in refractive index of an optical material at different wavelengths, representing the degree of dispersion of the material.

[0033] The field of view (FOV) in optical instruments is the angle between the two edges of the lens, representing the maximum range through which the image of the target object can pass through the lens. The size of the FOV determines the field of view of the optical instrument; a larger FOV results in a wider field of view but a lower optical magnification.

[0034] The object side and the image side are defined by the lens. The side where the subject is located is called the object side, and the surface of the lens closest to the object side can be called the object side surface. The side where the image of the subject is located is called the image side, and the surface of the lens closest to the image side can be called the image side surface.

[0035] An aperture stop is an edge, frame, or specially designed perforated barrier in an optical assembly used to limit the size of an imaging beam or a unit of imaging space.

[0036] Distortion, also known as image distortion, refers to the degree of distortion in the image formed by an optical system relative to the object itself. Distortion occurs due to the spherical aberration of the aperture. The height of the intersection point between the principal ray from different fields of view and the Gaussian image plane is not equal to the ideal image height; this difference is the distortion. Therefore, distortion only changes the imaging position of an off-axis object point on the ideal plane, causing a distortion in the image shape, but it does not affect the image's sharpness.

[0037] Existing hybrid telephoto lenses, as a key component of camera systems, effectively compensate for the shortcomings in imaging capabilities of devices such as mobile phones and drones, becoming one of the core technologies for improving the camera photography experience and product competitiveness. Under the current technological system, the realization of hybrid telephoto lenses mainly relies on optical structure design and the integration of optical components. However, due to the constraints of the hardware form factor of cameras such as mobile phones and drones, they face multiple challenges in achieving structural simplicity and miniaturization.

[0038] This invention introduces metasurface technology, an artificial planar material composed of subwavelength structural units capable of modulating the phase of light. Metalenses made using metasurfaces can be fabricated on very thin planes, offering new possibilities for further improving the performance of optical systems and shortening the overall lens length within limited space. Therefore, how to effectively apply metasurface technology to the optical lenses of devices such as mobile phones and drones to achieve small size, low chromatic aberration, and high imaging performance remains a pressing technical problem to be solved.

[0039] This invention combines the optical properties of traditional optical materials with those of metasurfaces, applying a hybrid refracto-metasurface system to applications requiring ultra-thinness, miniaturization, and high image quality, thus possessing broad application potential. Therefore, the following embodiments of this invention aim to effectively apply metasurface technology to mobile phone cameras to achieve the goals of ultra-thin structure, miniaturization, and high image quality.

[0040] Please see Figure 1 and Figure 6 This invention provides a hybrid telephoto lens with refractive and superconducting properties, comprising a first lens 110, a second lens 120, a third lens 140, and a prism 150 arranged along the optical axis from the object plane to the image plane; the first lens 110 is a spherical lens, the second lens 120 is a superconducting lens, and the third lens 140 is an aspherical lens; The first lens 110 has positive optical power, and its object side is convex and its image side is convex. The second lens 120 has positive optical power and its image-side surface has a microstructure arrangement; The third lens 140 has negative optical power, and its object side is convex, and its image side is convex.

[0041] In this embodiment, the superconducting telephoto lens uses only a combination of one superlens, two refractive lenses, and one prism 150. Its specific structure is that the first lens 110, the second lens 120, the third lens 140, and the prism 150 are arranged sequentially along the optical axis from the object plane to the image plane.

[0042] Specifically, the first lens 110 is configured as a spherical lens with positive optical power, and both the object-side and image-side surfaces are convex. This double-convex spherical design can effectively converge incident light rays, providing the main positive optical power contribution to the system. At the same time, the spherical surface shape is easy to process and inspect, which helps to control manufacturing costs. The second lens 120 is configured as a superlens, also with positive optical power. It includes a substrate and subwavelength-scale microstructures arranged on the image-side surface of the substrate. The period of the microstructures ranges from 250 to 400 nm, with an optimal period of 310 nm; the height of the microstructures ranges from 600 to 2000 nm, with an optimal height of 1500 nm in this embodiment; the diameter of the microstructures covers 110 to 210 nm, and the microstructures are arranged in shapes such as squares and regular hexagons. The substrate material is a visible light low-refractive-index glass material, such as D263TECO or BF33, etc., and the main part of the microstructure is a visible light high-refractive-index material, such as silicon nitride or titanium oxide. The microstructure may also include visible light low-refractive-index materials for protection, such as silicon oxide. By adaptively designing the geometric parameters of these microstructures (such as diameter, height, and period), the phase distribution of transmitted light waves can be modulated, thereby achieving optical power and correcting system aberrations. The object-side surface of the superlens is designed to be planar. The third lens 140 is set as an aspherical lens with negative optical power, and both its object-side and image-side surfaces are convex. This negative optical power biconvex aspherical lens is mainly used to compensate for residual aberrations generated by the first two positive lenses, especially field curvature and distortion, while the aspherical design provides more degrees of freedom for correcting higher-order aberrations. The prism 150 is used to deflect the optical path, enabling the entire optical system to be arranged in a periscope structure, effectively shortening the size of the lens module in the thickness direction of the terminal device. Through the above structural combination, the basic architecture of the telephoto lens is realized.

[0043] Based on this, this embodiment achieves an optimized balance between overall lens length and image quality. Since the second lens 120 uses a planar substrate superlens, it provides positive optical power while occupying almost no additional axial space, effectively shortening the air gap between the first lens 110 and the third lens 140. Simultaneously, the positive optical power of the first lens 110, the positive optical power of the second lens 120, and the negative optical power of the third lens 140 constitute a telephoto optical power distribution structure, allowing the principal plane of the system to shift forward, significantly compressing the distance from the object side of the first lens 110 to the image plane while achieving a long focal length. Ultimately, this lens provides good basic imaging performance while maintaining a compact size, achieving a miniaturized and high-quality telephoto lens.

[0044] In one embodiment, the superconducting telephoto lens satisfies: TTL / MIC ≤ 4.08; where TTL represents the distance from the center of the optical axis on the object side of the first lens 110 to the image plane, and MIC represents the maximum image circle size.

[0045] In this embodiment, the system is constrained to meet a specific size ratio: TTL / MIC ≤ 4.08. TTL is defined as the vertical distance from the center vertex of the optical axis on the object-side surface of the first lens 110 to the image plane, i.e., the total length of the optical system; MIC is defined as the maximum image circle diameter that the system can image. This relationship constrains the total length of the lens and the size of the imaging target surface. TTL / MIC ≤ 4.08 ensures a sufficiently large image plane (for high pixel requirements) while compressing the axial space of the entire optical system within a small range. From an optical principle perspective, the planar substrate and designable phase distribution of the superlens allow it to contribute the necessary optical power without increasing axial thickness; the prism 150 folds the optical path, so that the TTL measurement includes the folded optical path rather than the straight-line distance. Based on this, the constraint of this condition ensures that the lens can meet the stringent requirements of modern portable electronic devices (such as mobile phones) for extremely thin and light internal components, achieving compatibility between telephoto shooting functionality and the overall slim design of the device, i.e., achieving ultra-thin telephoto lens.

[0046] In one embodiment, the hybrid telephoto lens satisfies: 4.0 ≤ EFL / L1 ≤ 6.27; where EFL represents the effective focal length; and L1 represents the distance from the object-side surface of the first lens 110 to the object-side surface of the prism 150.

[0047] In this embodiment, the hybrid telephoto lens is required to satisfy the relationship 4.0 ≤ EFL / L1 ≤ 6.27. Here, EFL represents the effective focal length of the entire optical system, and L1 represents the axial distance from the vertex of the object-side surface of the first lens 110 to the vertex of the object-side surface of the prism 150. This ratio essentially defines the focal length magnification capability that the system can produce within a given physical space from the first lens 110 to the prism 150. If this ratio is lower than 4.0, it indicates insufficient optical power of the lens group, making it difficult to achieve a long focal length over a short distance; if the ratio is higher than 6.27, it introduces excessive aberration correction pressure, leading to a decrease in image quality.

[0048] Based on this, the relationship 4.0 ≤ EFL / L1 ≤ 6.27 ensures that the hybrid telephoto lens has efficient pre-focal length generation capability before optical path folding. The effect of this technology is manifested in achieving a focal length exceeding 28mm within a very limited physical length from the first lens 110 to the prism entrance 150, a level of compactness that is difficult to achieve with traditional pure refractive lenses. This limitation, while ensuring telephoto performance, avoids manufacturing tolerance sensitivity and image quality degradation caused by excessive focal length, achieving a balance between long focal length and high image quality.

[0049] In one embodiment, the hybrid telephoto lens further includes an aperture stop 130 located between the first lens 110 and the second lens 120, or the aperture stop 130 located between the second lens 120 and the third lens 140.

[0050] In this embodiment, the aperture stop 130, as an element limiting the aperture of the incident beam, has a decisive influence on the aberration correction and structural compactness of the lens. In a preferred embodiment of the present invention, as shown in Table 1 of Embodiment 1 below, surface number 5 is identified as the STOP aperture stop 130, which is located after surface number 4 (the image side of the second lens 120) and before surface number 6 (the object side of the third lens 140), that is, the aperture stop 130 is disposed between the second lens 120 and the third lens 140. The principle of placing the aperture stop 130 in this position is that after the light is converged by the first lens 110, it is then phase-modulated by the superlens of the second lens 120, at which point the beam aperture has been compressed to a certain extent; placing the aperture stop 130 after the superlens can effectively control the beam height entering the third lens 140, reduce the aperture of the third lens 140, thereby reducing the lens weight and cost. Meanwhile, the superlens exhibits a specific sensitivity to the incident angle. Positioning the aperture stop 130 close to or behind the superlens helps ensure that the superlens operates within its designed incident angle range, thus maintaining the accuracy of its phase modulation. In another feasible implementation, the aperture stop 130 can also be located between the first lens 110 and the second lens 120. This arrangement places the superlens behind the aperture stop 130, which helps control the beam aperture and incident angle distribution reaching the superlens surface, making it suitable for scenarios with special requirements on the duty cycle of the superlens microstructure.

[0051] Based on this, by flexibly positioning the aperture stop 130 between the first lens 110 and the second lens 120 or between the second lens 120 and the third lens 140, the effects of optimized aberration correction and reduced lens aperture can be achieved. Specifically, when the aperture stop 130 is located between the second lens 120 and the third lens 140, the radial dimension of the rear third lens 140 is effectively reduced, realizing the miniaturization and weight reduction of the optical system.

[0052] In one embodiment, the first lens 110 is made of glass, the second lens 120 is made of plastic or glass, the third lens 140 is made of plastic, and the prism 150 is made of plastic or glass.

[0053] In this embodiment, the first lens 110, as the first lens directly exposed to the external environment (or close to the object), is made of glass material, which can provide excellent scratch resistance and thermal stability, ensuring that the focal position drift of the lens is minimal under different temperature conditions. This is crucial for meeting the high and low temperature reliability test requirements.

[0054] Furthermore, the first lens 110 can be made of high-refractive-index glass, which is beneficial for enhancing optical power and reducing the radius of curvature. The second lens 120, as a superlens, can be made of glass as its substrate; a glass substrate has a low coefficient of thermal expansion, which is beneficial for the morphological stability of the micro / nano structure under temperature changes, thus ensuring phase control accuracy. The third lens 140 is made of plastic, and injection molding can be used to fabricate complex aspherical surfaces at low cost and high efficiency to correct higher-order aberrations in the system, while reducing the overall weight of the lens. The prism 150 is preferably made of glass to ensure the critical angle of total internal reflection and reduce the length of the prism 150; in low-end applications, the prism 150 can also be made of transparent plastic to further reduce costs.

[0055] In one embodiment, the prism 150 is one of a flat glass, a right-angle prism, a roof prism, or a cemented composite prism.

[0056] In this embodiment, the prism 150 functions to fold the optical axis, causing the long focal length optical path, originally extending along the incident light direction, to be redirected, thereby converting the physical length (height) of the lens into space along the thickness or length direction of the device. Flat glass and right-angle prisms are common optical path folding elements, both rotating the optical axis by 90 degrees through total internal reflection. They are simple in structure and easy to manufacture. The figure only illustrates flat glass; in reality, the optical path lengths of flat glass and right-angle prisms are the same. The roof prism adds a roof surface to the right-angle prism, enabling the conversion of an inverted image into an upright image, suitable for systems requiring visual observation. The cemented composite prism is composed of two or more prisms cemented together, simultaneously achieving optical path folding and chromatic aberration correction. For example, cementing glass prisms with different refractive indices and Abbe numbers can compensate for the dispersion introduced by the prism 150 itself.

[0057] In this embodiment, a flat glass or right-angle prism (equivalent to a primary reflection prism 150) is preferably used as the optical path reversal element. This primary reflection structure is simple, the manufacturing process is mature, and it has little impact on the polarization state. However, in applications requiring further compression of dimensions in specific directions or correction of image reversal, a roof prism can be used as an alternative. A roof prism contains two reflecting surfaces at a 90-degree angle, which can achieve left-right image flipping while reversing the optical path, thereby obtaining an upright image. In addition, a cemented composite prism is made of two or more prisms cemented together, which can achieve more complex optical path folding, such as shortening the physical length of the prism or the beam splitting function. For example, when the prism 150 needs to meet the condition n*L≤44.95mm, selecting a glass material with a higher refractive index to make the cemented composite prism can effectively reduce the geometric length L of the prism 150.

[0058] In one embodiment, the hybrid telephoto lens further includes a filter 160 located on the image side of the prism 150.

[0059] In this embodiment, the main function of the filter 160 is to filter out infrared light to avoid unnecessary signal interference on the image sensor, thereby ensuring accurate color reproduction. This embodiment places the filter 160 on the image-side of the prism 150 (i.e., between the prism 150 and the imaging plane 200), which is beneficial for space utilization and optical path design. The filter 160 protects the photosensitive area of ​​the image sensor from dust contamination. Furthermore, at this location, the light beam has already been sufficiently refracted and converged by the prism 150, resulting in a relatively small beam aperture. Therefore, the size of the filter 160 can be made smaller, which helps reduce component costs. In addition, placing the filter 160 after the prism 150 avoids the problem of multiple reflections and stray light that may occur before the light enters the prism 150, as the total internal reflection inside the prism 150 is sensitive to stray light.

[0060] In one embodiment, the prism 150 satisfies n*L≤44.95mm, where n is the refractive index of the prism 150 and L is the length of the prism 150.

[0061] In this embodiment, the conditional expression of prism 150 is used to control the optical path length (the product of refractive index and geometric length) of light propagating inside prism 150 to not exceed a specific threshold. The product of the actual geometric path traveled by light in prism 150 and the refractive index of prism 150 determines the effective optical path length of light propagating in the medium. Since this invention adopts a hybrid refractive-hyper-prism architecture and includes prism 150, the total optical path TTL includes the propagation distance of light in air, lens, and prism 150. If the optical path length nL of prism 150 is too large, it means that either the length L of prism 150 is too long (occupying too much structural space), or the refractive index n is too high (which may lead to increased material costs or decreased transmittance). For example, in Embodiment 1 below, the refractive index of prism 150 is approximately 1.583, the length L of prism 150 is approximately 28.39 mm according to Table 1, and the calculated value of nL is approximately 44.94 mm, which is less than the limit of 44.95 mm, indicating that this embodiment has a significant advantage in miniaturization of prism 150.

[0062] Based on this, by constraining n*L≤44.95mm, the present invention ensures that the contribution of the prism 150 part to the overall volume and weight of the lens is within a controlled range; and avoids the problems of increased module thickness, reduced transmittance and increased cost caused by the prism 150 being too long or having too high a refractive index.

[0063] In one embodiment, the focal length f of the hybrid telephoto lens satisfies: f ≥ 28 mm.

[0064] In this embodiment, the focal length f is a key parameter determining the lens's shooting angle and telephoto capability. In portable devices such as mobile phones, the focal length of the main wide-angle lens is typically around 24mm to 28mm (equivalent to full-frame). To achieve 2x or 3x optical zoom, the equivalent focal length of the telephoto lens needs to reach 50mm or more. Considering the crop factor of the image sensor, the actual physical focal length usually needs to be greater than 14mm or even 20mm. The f≥28mm specified in this invention indicates that, within a specific image sensor size (such as 1 / 2 inch or smaller), it can provide extremely strong telephoto magnification capability, i.e., achieve high-magnification optical zoom.

[0065] For example, in Embodiment 1 of the present invention described below, the effective focal length (EFL) is 28.15 mm; in Embodiment 2, the effective focal length (EFL) is 28.27 mm, both of which satisfy the requirement of f ≥ 28 mm. To achieve this relatively long focal length while maintaining a total lens length (TTL) of only about 35 mm, the present invention employs the aforementioned telephoto optical power distribution (positive-positive-negative) and a space compression strategy of using a superlens to replace a thick lens. Specifically, the first lens 110 provides strong positive optical power, the second lens 120 supplements positive optical power within a limited space, and the negative optical power of the third lens 140 further shifts the principal plane towards the object side, thereby increasing the back focal length and effective focal length without significantly increasing the physical length.

[0066] In one embodiment, the field of view (Fov) of the super-refractive telephoto lens satisfies: Fov ≥ 18°.

[0067] In this embodiment, the geometric relationship between the field of view (Fov), focal length (f), and image plane size (MIC) satisfies: Fov = 2 * arctan(MIC / (2 * f)). This invention, while maintaining a relatively long focal length (f ≥ 28mm), still provides a diagonal field of view greater than or equal to 18°, indicating that it has a relatively large image plane coverage or a reasonable framing range. The key to achieving this field of view lies in the fact that the first lens 110 and the second lens 120 effectively converge light rays incident at large angles, and the aspherical surface of the third lens 140 specifically corrects aberrations in the off-axis field of view, allowing light rays from the edge of the field of view to converge well onto the image plane.

[0068] In one embodiment, the aperture number F of the hybrid telephoto lens satisfies F≤3.5.

[0069] In this embodiment, the aperture number F is the ratio of the lens focal length to the entrance pupil diameter, which determines the amount of light entering the lens. The smaller the aperture number F, the larger the aperture, the more light enters, resulting in a higher signal-to-noise ratio in low-light environments and a shallower depth of field. For telephoto lenses, achieving a small F# value is quite difficult due to the long focal length, as this requires a large entrance pupil diameter. A larger entrance pupil diameter increases the difficulty of correcting off-axis aberrations. However, the superlens of this invention, through its flexible phase modulation capability, effectively shares the aberration correction burden of traditional lenses, allowing the MTF (Mean Transmission Frequency) to remain at a high level across the entire field of view even under large aperture conditions.

[0070] Based on the above solutions, the present invention provides the following various feasible specific embodiments.

[0071] Example 1: like Figure 1 As shown, the superconducting telephoto lens provided in Embodiment 1 of the present invention includes a first lens 110, a second lens 120, an aperture 130, a third lens 140, a prism 150, and a filter 160 arranged along the optical axis from the object plane to the image plane.

[0072] The first lens 110 has positive optical power, its object side is convex, and its image side is convex; both its object side and image side are spherical, and its material is glass.

[0073] The second lens 120 has positive optical power, its image side has a microstructure arrangement, its object side is a plane, and its material is glass.

[0074] The third lens 140 has negative optical power, its object side is convex, its image side is convex, both its object side and image side are aspherical, and its material is plastic.

[0075] The prism 150 is made of flat glass or a right-angle prism (the figure only shows the flat glass as an example, but in reality, the optical path of the flat glass and the right-angle prism is the same).

[0076] like Figure 1 As shown, the incident light passes sequentially through the first lens 110, the second lens 120, the aperture 130, the third lens 140, the prism 150, and the filter 160, and converges on the imaging surface 200.

[0077] For example, Table 1 details the specific optical data parameters of each lens in the hybrid telephoto lens provided in Embodiment 1 of the present invention, using a feasible implementation method. The optical data parameters in Table 1 correspond to... Figure 1 The telephoto lens shown is a hybrid of refractive and hyper-refractive power at room temperature.

[0078] Table 1:

[0079] In Table 1, the surface numbers are assigned according to the surface sequence of each lens. For example, surface number 1 represents the object side of the first lens 110, surface number 2 represents the image side of the first lens 110, and so on. Metasurface represents a metasurface, STOP represents an aperture stop 130, Even Asphere represents an aspherical surface, and Standard represents a standard surface; IMAGE represents the imaging surface 200; the radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the lens surface bends towards the image surface and a negative value indicating that the lens surface bends towards the object surface; the spacing represents the central axial distance from the current surface to the next surface; and the aperture represents the effective light-transmitting diameter of the current lens surface. The units for radius of curvature, spacing, and aperture are all millimeters (mm).

[0080] The surface shape of an aspherical lens satisfies the following equation: ; Where z is the distance from the vertex of the extended aspherical surface along the optical axis, and r is the height from the optical axis. For normalized radial coordinates, c is the curvature 1 / R, R is the radius of curvature at the lens vertex; K is the conic coefficient, N is the highest term number, and a i The coefficients of the 2i-th order polynomials are a2, a3, a4, a5, a6, a7, and a8, which correspond to the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order aspherical higher-order coefficients, respectively.

[0081] For example, Table 2 details the higher-order coefficients a2, a3, a4, a5, a6, a7, and a8 of the aspherical lens surface in this embodiment, using a feasible implementation method.

[0082] Table 2:

[0083] In Table 2, the value of coefficient a2 with face number 6 is 8.51E-01, and so on.

[0084] For example, Table 3 illustrates the phase of the metasurface in this embodiment with a feasible implementation: Table 3:

[0085] Where R1 is the normalized radius of the binary surface of the superlens; A1 to A10 represent the coefficients of the metasurface phase. The phase expression of the superlens is: Where ρ = R / R1, R is the radius of the metasurface, and A i Let N be the phase coefficient of the metasurface, and N be the number of terms in the polynomial.

[0086] In this case, the metasurface layer of the superlens is composed of periodically arranged nanopillars, such as... Figure 11 As shown, the arrangement is hexagonal, and the period of the nanopillars is p = 310 nm. Figure 12 As shown, the nanopillars have a height h1 = 1500 nm and a refractive index n = 2.3. A protective layer exists outside the nanopillars, with a height h2 = 3400 nm and a refractive index n = 1.52. The nanopillar diameters range from 110 nm to 210 nm. The relationships between the nanopillar transmittance and phase and the nanopillar diameter are shown below. Figure 13 As shown in (a) and (b) in the figure. The diameter of the nanopillars at different positions of the metasurface lens can be obtained based on the phase distribution formula of the metasurface lens, such as... Figure 14 As shown.

[0087] Based on the specific optical data parameters exemplified in Example 1 of this embodiment, the hybrid telephoto lens achieves the design structure shown in Table 4 below. Table 4:

[0088] In Table 4, the application wavelength of the hybrid telephoto lens provided in this embodiment is the visible light band; the F number is 3.5, the effective focal length is 28.15mm, the maximum field of view is 18.07°, and the total TTL length is 35.49mm.

[0089] Figure 2 This is a schematic diagram of the visible light MTF of the superconducting telephoto lens provided in Embodiment 1 of the present invention; as shown. Figure 2 As shown, in this embodiment of the invention, when the F-number is 3.5 and the effective focal length is 28.15mm, the sagittal and meridional directions of the MTF in the entire field of view are relatively concentrated, and the MTF value is almost close to the diffraction limit. Therefore, it can meet the requirements of high-resolution imaging.

[0090] Figure 3 This is a schematic diagram of the blur pattern of the telephoto lens with hybrid refractive and hyper-refractive properties provided in Embodiment 1 of the present invention; as shown. Figure 3 As shown, the dispersion pattern of this invention is relatively concentrated and uniformly distributed throughout the long wavelength band, which can meet the requirements of high-resolution imaging.

[0091] Figure 4 This is a schematic diagram of the transverse chromatic aberration of the telephoto lens with refracting and hyperchromatic hybrid technology provided in Embodiment 1 of the present invention; as shown... Figure 4 As shown, the telephoto lens provided in this embodiment of the invention has a transverse chromatic aberration value of <0.8µm in the visible light operating band within a 1.0 field of view.

[0092] Figure 5This is a schematic diagram of field curvature and distortion of a hybrid telephoto lens provided in Embodiment 1 of the present invention. The diagram illustrates the field curvature and distortion for different wavelengths corresponding to different fields of view (normalized field of view), i.e., the distance the image plane deviates from the ideal plane, and the distortion. Figure 5 As shown, the telephoto lens provided in Embodiment 1 of the present invention exhibits a distortion of less than 0.3% across the entire field of view in the visible light operating band.

[0093] Example 2: like Figure 6 As shown, the superconducting telephoto lens provided in Embodiment 2 of the present invention includes a first lens 110, a second lens 120, an aperture 130, a third lens 140, a prism 150, and a filter 160 arranged along the optical axis from the object plane to the image plane.

[0094] The first lens 110 has positive optical power, its object side is convex, and its image side is convex; both its object side and image side are spherical, and its material is glass.

[0095] The second lens 120 has positive optical power, its image side has a microstructure arrangement, its object side is a plane, and its material is glass.

[0096] The third lens 140 has negative optical power, its object side is convex, its image side is convex, both its object side and image side are aspherical, and its material is plastic.

[0097] The prism 150 is made of flat glass or a right-angle prism (the figure only shows the flat glass as an example, but in reality, the optical path of the flat glass and the right-angle prism is the same).

[0098] like Figure 6 As shown, the incident light passes sequentially through the first lens 110, the second lens 120, the aperture 130, the third lens 140, the prism 150, and the filter 160, and converges on the imaging surface 200.

[0099] For example, Table 5 details the specific optical data parameters of each lens in the hybrid telephoto lens provided in Embodiment 2 of the present invention, using a feasible implementation method. The optical data parameters in Table 5 correspond to... Figure 5 The telephoto lens shown is a hybrid of refractive and hyper-refractive power at room temperature.

[0100] Table 5:

[0101] In Table 5, the surface numbers are assigned according to the surface sequence of each lens. For example, surface number 1 represents the object side of the first lens 110, surface number 2 represents the image side of the first lens 110, and so on. Metasurface represents a metasurface, STOP represents an aperture stop 130, Even Asphere represents an aspherical surface, and Standard represents a standard surface; IMAGE represents the imaging surface 200; the radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the lens surface bends towards the image surface and a negative value indicating that the lens surface bends towards the object surface; the spacing represents the central axial distance from the current surface to the next surface; and the aperture represents the effective light-transmitting diameter of the current lens surface. The units for the radius of curvature, spacing, and aperture are all millimeters (mm).

[0102] The surface shape of an aspherical lens satisfies the following equation: ; Where z is the distance from the vertex of the extended aspherical surface along the optical axis, and r is the height from the optical axis. For normalized radial coordinates, c is the curvature 1 / R, R is the radius of curvature at the lens vertex; K is the conic coefficient, N is the highest term number, and a i The coefficients of the 2i-th order higher polynomials are: a2, a3, a4, a5, a6, a7, a8, a9, a 10 These correspond to the 4th, 6th, 8th, 10th, 12th, 14th, 16th, 18th, and 20th order aspherical higher-order coefficients, respectively.

[0103] For example, Table 6 details the higher-order coefficients a2, a3, a4, a5, a6, a7, a8, a9, and a6 on the surface of the aspherical lens in this embodiment, using a feasible implementation method. 10 .

[0104] Table 6:

[0105] In Table 6, the coefficient a2 with face number 6 has a value of 7.05E-01, and so on.

[0106] For example, Table 7 illustrates the phase of the metasurface in this embodiment with a feasible implementation: Table 7:

[0107] Where R1 is the normalized radius of the binary surface of the superlens; A1 to A10 represent the coefficients of the metasurface phase. The phase expression of the superlens is: Where ρ = R / R1, R is the radius of the metasurface, and A i Let N be the phase coefficient of the metasurface, and N be the number of terms in the polynomial.

[0108] In this case, the metasurface layer of the superlens is composed of periodically arranged nanopillars, such as... Figure 11 As shown, the arrangement is hexagonal, and the period of the nanopillars is p = 310 nm. Figure 12 As shown, the nanopillars have a height h1 = 1500 nm and a refractive index n = 2.3. A protective layer exists outside the nanopillars, with a height h2 = 3400 nm and a refractive index n = 1.52. The nanopillar diameters range from 110 nm to 210 nm. The relationships between the nanopillar transmittance and phase and the nanopillar diameter are shown below. Figure 13 As shown in (a) and (b) in the figure. The diameter of the nanopillars at different positions of the metasurface lens can be obtained based on the phase distribution formula of the metasurface lens, such as... Figure 15 As shown. It should be noted that the diameter of the nanopillars in Examples 1 and 2 can be selected within the above range according to the desired target phase and nanopillar transmittance, thereby forming different phase distributions to adapt to different optical parameter requirements.

[0109] Based on the specific optical data parameters exemplified in this second embodiment, the hybrid telephoto lens achieves the design structure shown in Table 8 below. Table 8:

[0110] In Table 8, the application wavelength of the hybrid telephoto lens provided in this embodiment is the visible light band; the F number is 2.8, the effective focal length is 28.27mm, the maximum field of view is 18.0°, and the total TTL length is 36.6mm.

[0111] Figure 7 This is a schematic diagram of the visible light MTF of the superconducting telephoto lens provided in Embodiment 2 of the present invention; as shown. Figure 7 As shown, in this embodiment of the invention, when the F-number is 2.8 and the effective focal length is 28.27mm, the MTF of the entire field of view is >0.35 at 200lp / mm, which can meet the requirements of high-resolution imaging.

[0112] Figure 8 This is a schematic diagram of the blur pattern of the telephoto lens with super-refractive optical distortion provided in Embodiment 2 of the present invention; as shown. Figure 8 As shown, the dispersion pattern of this invention is relatively concentrated and uniformly distributed throughout the long wavelength band, which can meet the requirements of high-resolution imaging.

[0113] Figure 9 This is a schematic diagram of the transverse chromatic aberration of the telephoto lens with refracting and hyperchromatic hybrid technology provided in Embodiment 2 of the present invention; as shown... Figure 9 As shown, the telephoto lens provided in this embodiment of the invention has a transverse chromatic aberration value of <1.0 μm within a 1.0 field of view in the visible light operating band.

[0114] Figure 10 This is a schematic diagram of field curvature and distortion of a hybrid telephoto lens provided in Embodiment 2 of the present invention. The diagram illustrates the field curvature for different wavelengths corresponding to different fields of view (normalized field of view), i.e., the distance the image plane deviates from the ideal plane, and the distortion. Figure 10 As shown, the telephoto lens provided in Embodiment 1 of the present invention exhibits a distortion of less than 0.2% across the entire field of view in the visible light operating band.

[0115] In summary, as described in Embodiments 1 and 2, this invention, through the specific optical power combination and surface design of the three lenses and prism 150, achieves efficient optical convergence and aberration balance while ensuring a long focal length. Simultaneously, by utilizing the phase-adjusting capability of a superlens to replace multiple traditional lenses, the number of lenses is significantly reduced, lowering the overall length and weight of the lens. It possesses advantages such as simple structure, miniaturization, short overall length, high image quality, and low chromatic aberration.

[0116] This invention also provides a camera module, including the hybrid telephoto lens described above. Because the camera module uses the aforementioned hybrid telephoto lens, it also possesses advantages such as miniaturization, short overall length, high image quality, and low chromatic aberration, comparable to optical lenses.

[0117] This invention also provides a terminal device, including the camera module described above. The electronic device can be a terminal device with video or photo capture capabilities, such as a mobile phone, tablet computer, laptop, camcorder, video recorder, camera, intelligent robot, or other devices with photo or video capture capabilities.

[0118] Finally, it should be noted that the above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A telephoto lens with hybrid refracting and hyperfocal projection, characterized in that, It includes a first lens, a second lens, a third lens, and a prism arranged along the optical axis from the object plane to the image plane; the first lens is a spherical lens, the second lens is a superlens, and the third lens is an aspherical lens; The first lens has positive optical power, and its object side is convex, and its image side is convex. The second lens has positive optical power and its image-side surface has a microstructure arrangement; The third lens has negative optical power, and its object side is convex, as is its image side.

2. The telephoto lens with hybrid refractive and hyperfocal projection according to claim 1, characterized in that, The hybrid telephoto lens satisfies the following condition: TTL / MIC ≤ 4.08; Where TTL represents the distance from the center of the optical axis on the side of the first lens to the image plane, and MIC represents the maximum image circle size.

3. The telephoto lens with hybrid refractive and hyperfocal projection according to claim 1, characterized in that, The hybrid telephoto lens satisfies the following condition: 4.0 ≤ EFL / L1 ≤ 6.27; Wherein, EFL represents the effective focal length; L1 represents the distance from the object-side surface of the first lens to the object-side surface of the prism.

4. The telephoto lens with hybrid refractive and hyperfocal projection according to claim 1, characterized in that, It also includes an aperture stop, which is located between the first lens and the second lens, or between the second lens and the third lens.

5. The telephoto lens with hybrid refractive and hyperfocal projection according to claim 1, characterized in that, The first lens is made of glass, the second lens is made of plastic or glass, the third lens is made of plastic, and the prism is made of plastic or glass.

6. The telephoto lens with hybrid refractive and hyperfocal projection according to claim 1, characterized in that, The prism is one of the following: flat glass, right-angle prism, roof prism, or cemented composite prism.

7. The telephoto lens with hybrid refractive and hyperfocal projection according to claim 1, characterized in that, It also includes a filter located on the image side of the prism.

8. The telephoto lens with hybrid refractive and hyperfocal projection according to claim 1, characterized in that, The prism satisfies n*L≤44.95mm, where n is the refractive index of the prism and L is the length of the prism.

9. The telephoto lens with hybrid refractive and hyperfocal projection according to any one of claims 1 to 8, characterized in that, The focal length f of the hybrid telephoto lens satisfies: f≥28mm.

10. The telephoto lens with hybrid refractive and hyper-refractive power according to any one of claims 1 to 8, characterized in that, The field of view (Fov) of the hybrid telephoto lens satisfies: Fov ≥ 18°.

11. The telephoto lens with hybrid refractive and hyper-refractive power according to any one of claims 1 to 8, characterized in that, The aperture F of the hybrid telephoto lens satisfies F≤3.

5.

12. A camera module, characterized in that, Including the telephoto lens with super-refractive hybrid structure as described in any one of claims 1-11 above.

13. A terminal device, characterized in that, Including the camera module as described in claim 12 above.

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