Optical system, imaging device, and electronic device

Abstract

An optical system includes, in order from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens, wherein at least one lens of the first lens, the second lens, the third lens, and the fourth lens is a superlens, and the remaining lenses of the first lens, the second lens, the third lens, and the fourth lens are refractive lenses, and wherein the first lens, the second lens, the third lens, and the fourth lens are configured such that the optical system satisfies: f / EPD < 3.0, and HFOV ≤ 24°, wherein f is an effective focal length of the optical system, EPD is an entrance pupil diameter of the optical system, and HFOV is half of a maximum field of view angle of the optical system.

Description

Technical Field

[0001] This disclosure relates to the field of optical imaging technology, and in particular to an optical system, imaging device and electronic device. Background Technology

[0002] As the size and thickness of electronic devices such as smartphones gradually decrease, the total track length (TTL) of the lenses in the optical systems mounted on these devices needs to be shortened as much as possible. However, this reduction in the total track length also places higher demands on the hardware requirements of image sensors and the optical performance of imaging systems.

[0003] Currently, traditional mobile phone telephoto lenses generally have a large number of lens elements (usually 6-7) to meet shooting requirements such as large aperture, long focal length and portrait effect, which makes lens assembly very difficult and costly.

[0004] How to reduce the number of lenses while achieving better telephoto shooting results is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This disclosure provides an optical system, imaging device, and electronic device to alleviate, reduce, or eliminate the aforementioned problems.

[0006] According to one aspect of this disclosure, an optical system is provided, comprising: a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side to the image side, wherein at least one of the first lens, the second lens, the third lens, and the fourth lens is a superlens, and the remaining lenses of the first lens, the second lens, the third lens, and the fourth lens are refractive lenses, and wherein the first lens, the second lens, the third lens, and the fourth lens are configured such that the optical system satisfies: f / EPD < 3.0 and HFOV ≤ 24°, where f is the effective focal length of the optical system, EPD is the entrance pupil diameter of the optical system, and HFOV is half of the maximum field of view of the optical system.

[0007] According to one aspect of this disclosure, an imaging apparatus is provided, including the optical system of the foregoing aspect and an image sensor array, the image sensor array being used to generate image data based on light transmitted through the optical system.

[0008] According to one aspect of this disclosure, an electronic device is provided, including the imaging device of the foregoing aspect.

[0009] The optical system and imaging device and electronic device including the optical system according to the embodiments of the present disclosure employ a combination of superlens and refractive lenses, which makes it easier to compensate for chromatic aberration and improves imaging quality such as chromatic aberration. In order to meet the requirements of detail recognition of distant targets, the optical system has a long focal length. By setting f / EPD<3.0 and HFOV≤24°, the above requirements are met while reducing the number of lenses in the optical system, thus promoting the lightweighting and miniaturization of the system.

[0010] These and other aspects of this disclosure will be apparent from the embodiments described below, and will be elucidated with reference to the embodiments described below. Attached Figure Description

[0011] Further details, features, and advantages of this disclosure are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0012] Figure 1 A schematic cross-sectional view of an optical system provided in an embodiment of this disclosure along the optical axis.

[0013] Figure 2 A schematic diagram of the field of view of the optical system provided in the embodiments of this disclosure;

[0014] Figure 3 A schematic cross-sectional view of an optical system provided in an embodiment of this disclosure along the optical axis.

[0015] Figure 4 for Figure 3 The distortion curve of the provided optical system;

[0016] Figure 5 for Figure 3 Astigmatism curves of the provided optical system;

[0017] Figure 6 for Figure 3 The magnification chromatic aberration curve of the provided optical system;

[0018] Figure 7 for Figure 3 The axial chromatic aberration curve of the provided optical system;

[0019] Figure 8 This is another optional cross-sectional schematic diagram of the optical system provided in an embodiment of the present disclosure along the optical axis.

[0020] Figure 9 for Figure 8 The distortion curve of the provided optical system;

[0021] Figure 10 for Figure 8 Astigmatism curves of the provided optical system;

[0022] Figure 11 for Figure 8 The magnification chromatic aberration curve of the provided optical system;

[0023] Figure 12 for Figure 8 The axial chromatic aberration curve of the provided optical system;

[0024] Figure 13 Another optional cross-sectional schematic diagram of the optical system provided in this embodiment of the present disclosure along the optical axis;

[0025] Figure 14 for Figure 13 The distortion curve of the provided optical system;

[0026] Figure 15 for Figure 13 Astigmatism curves of the provided optical system;

[0027] Figure 16 for Figure 13 The magnification chromatic aberration curve of the provided optical system;

[0028] Figure 17 for Figure 13 The axial chromatic aberration curve of the provided optical system;

[0029] Figure 18 Another optional cross-sectional schematic diagram of the optical system provided in this embodiment of the present disclosure along the optical axis;

[0030] Figure 19 for Figure 18 The distortion curve of the provided optical system;

[0031] Figure 20 for Figure 18 Astigmatism curves of the provided optical system;

[0032] Figure 21 for Figure 18 The magnification chromatic aberration curve of the provided optical system;

[0033] Figure 22 for Figure 18 The axial chromatic aberration curve of the provided optical system;

[0034] Figure 23 Another optional cross-sectional schematic diagram of the optical system provided in this embodiment of the present disclosure along the optical axis;

[0035] Figure 24 for Figure 23 The distortion curve of the provided optical system;

[0036] Figure 25 for Figure 23Astigmatism curves of the provided optical system;

[0037] Figure 26 for Figure 23 The magnification chromatic aberration curve of the provided optical system;

[0038] Figure 27 for Figure 23 The axial chromatic aberration curve of the provided optical system;

[0039] Figure 28 Another example cross-sectional schematic diagram of the optical system provided in the embodiments of this disclosure along the optical axis;

[0040] Figure 29 for Figure 28 The distortion curve of the provided optical system;

[0041] Figure 30 for Figure 28 Astigmatism curves of the provided optical system;

[0042] Figure 31 for Figure 28 The magnification chromatic aberration curve of the provided optical system;

[0043] Figure 32 for Figure 28 The axial chromatic aberration curve of the provided optical system. Detailed Implementation

[0044] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure. Therefore, the drawings and description are to be considered exemplary in nature and not restrictive.

[0045] With the rapid development of mobile phones and other electronic devices, these devices are equipped with more diverse imaging optical systems. Generally speaking, imaging optical systems include telephoto optical systems to meet the shooting requirements of large aperture, long focal length, and portrait effects.

[0046] Telephoto optical systems, also known as long focal length optical systems, refer to optical systems with a longer focal length than standard optical systems. Telephoto optical systems generally have a narrower angle of view, making them suitable for capturing details of distant objects and subjects that are difficult to approach, especially for shooting distant landscapes, portraits, and other similar scenarios. To meet the requirements of telephoto shooting, aspherical optical lenses are typically used to construct multi-element optical systems. However, as the number of aspherical optical lenses increases, the total track length (TTL) of the entire optical system also increases, leading to higher demands on lens assembly complexity and cost.

[0047] To reduce the overall length of the lens while improving telephoto shooting performance, this disclosure employs a design combining metalenses and refractive lenses. A metalense, also known as a meta-lens, is a two-dimensional planar lens structure, an optical element that focuses light using a metasurface, where the metasurface can be considered a planar two-dimensional (2D) nanostructure with subwavelength thickness.

[0048] Figure 1 This is a schematic cross-sectional view of an optical system provided in an embodiment of the present disclosure along the optical axis. Figure 2 This is a schematic diagram of the field of view of an optical system provided in an embodiment of this disclosure. Figure 1-2 As shown in the figure, the left side is the object side and the right side is the image side. The optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 arranged sequentially from the object side to the image side. At least one of the first lens 110, second lens 120, third lens 130, and fourth lens 140 is a superlens, and the remaining lenses are refractive lenses. It should be noted that in some cases, a superlens can also be considered a form of refractive lens, but in this disclosure, refractive lenses do not include superlenses; that is, the refractive lenses in this disclosure are non-superlenses. In some embodiments, the optical system 100 includes only four optical lenses—the first lens 110, second lens 120, third lens 130, and fourth lens 140—from the object side to the image side, to reduce the overall lens length and manufacturing / assembly cost of the entire optical system 100.

[0049] In this optical system 100, it is necessary to control the F-number (i.e., the effective focal length divided by the aperture) of the optical system to meet the optical characteristics required for telephoto shooting. Therefore, the first lens 110, the second lens 120, the third lens 130 and the fourth lens 140 are configured such that the optical system 100 satisfies: f / EPD < 3.0 and HFOV ≤ 24°, where f is the effective focal length of the optical system, EPD is the entrance pupil diameter of the optical system, i.e., the aperture diameter, which is limited by the aperture stop diameter; and HFOV is the half field of view θ of the optical system, i.e., half of the maximum field of view of the optical system.

[0050] This disclosure employs a combination of superlenses and refractive lenses, which makes it easier to compensate for chromatic aberration and improves imaging quality such as chromatic aberration. In order to meet the requirements for detail recognition of distant targets, the optical system has a long focal length. By setting f / EPD < 3.0 and HFOV ≤ 24°, the above requirements are met while reducing the number of lenses in the optical system, thus promoting the lightweight and miniaturization of the system.

[0051] In some embodiments of the present disclosure, both the object-side surface and the image-side surface of each of the refractive lenses include an aspheric surface. Compared with conventional spherical lenses, the surface shape of an aspheric lens is more complex, and the expression adopted for the aspheric surface is:

[0052]

[0053] wherein z is the surface sag parallel to the optical axis direction of the optical system, c is the curvature at the center point of the aspheric surface, k is the quadric constant, that is the conic constant, A to J respectively correspond to high-order coefficients, and m is the maximum order of the aspheric surface.

[0054] In some embodiments of the present disclosure, the remaining lenses include at least two refractive lenses, and the refractive index difference of any two of the at least two refractive lenses satisfies: 0.01<|n i -n j |<0.2, wherein i and j are both refractive lens numbers, n i is the refractive index of the i-th refractive lens in the direction from the object side to the image side, n j is the refractive index of the j-th refractive lens in the direction from the object side to the image side, and i is not equal to j.

[0055] Further, each of the refractive lenses has an Abbe number satisfying 18<V<57, wherein V is the Abbe number. In the design, appropriate materials, that is, refractive index and Abbe number, are selected for the refractive lenses, which, combined with the modulation of each wavelength by the metalens, can compensate chromatic aberration more effectively, and the improvement of axial chromatic aberration under large aperture is more advantageous especially for telephoto optical systems.

[0056] In some embodiments of the present disclosure, the first lens, the second lens, the third lens and the fourth lens are further configured such that the optical system satisfies: 0.4<|f Mi / f|<50, wherein f Mi is the focal length of any metalens in the at least one lens. That is, when a plurality of metalenses are included at the same time, each of the plurality of metalenses needs to satisfy 0.4<|f Mi / f|<50.

[0057] In some embodiments of the present disclosure, any metalens in the at least one lens comprises a base layer and at least one nanostructure layer stacked on the base layer, and at least one of the at least one nanostructure layer comprises polarization-insensitive periodically arranged nanostructures.

[0058] In some embodiments of the present disclosure, any metalens in the at least one lens has a thickness satisfying 0.07mm<t x <1.0mm, wherein x is a metalens number, t xis the thickness of the x-th metalens in the direction from the object side to the image side. It should be noted that the thickness of any metalens refers to the maximum dimension of the metalens in the optical axis direction. When the thickness of any metalens meets the above requirements, the adjustment space for the air gap between lenses can be increased within the limited total track length (TTL) of the lens when the TTL is determined, so that the parameter degree of freedom of the entire optical system is higher.

[0059] In some embodiments of the present disclosure, the first lens 110, the second lens 120, the third lens 130 and the fourth lens 140 are further configured such that the optical system 100 satisfies: 2 < f*EPD / TTL < 5, wherein TTL is the total track length of the lens, that is, the distance from the first surface of the first lens 110 (the surface close to the object side) to the image plane IS, or more specifically, the intersection point O of the first surface of the first lens and the optical axis 11 to the focal point F of the optical system. Under the condition of controlling the total track length TTL of the lens to be small, the effective focal length and the system aperture are maximized as much as possible, ensuring sufficient magnification and aperture size of the imaging system, enabling it to have a portrait shooting effect, and the system has the advantage of miniaturization.

[0060] In some embodiments of the present disclosure, the first lens 110, the second lens 120, the third lens 130 and the fourth lens 140 are further configured such that the optical system 100 satisfies: f*IMGH / N > 11, wherein IMGH is the maximum imaging height of the optical system 100 (e.g. Figure 2 shown), N is the total number of lenses in the optical system. Optionally, N=4, that is, the optical system 100 in the present disclosure only includes 4 lenses. In the imaging area 200 of a large target surface, the present disclosure uses the smallest possible number of lenses to keep the effective focal length of the optical system at a large level, achieving the portrait shooting effect.

[0061] In some embodiments of the present disclosure, the first lens 110, the second lens 120, the third lens 130 and the fourth lens 140 are further configured such that the optical system 100 satisfies: 0.5 < T 34 / (CT3+CT4) < 7, wherein T 34 is the air spacing between the third lens and the fourth lens, CT3 is the central thickness of the third lens, and CT4 is the central thickness of the fourth lens. It can be understood that the central thickness of a lens refers to the distance between two intersection points formed by the optical axis and the two surfaces of the lens, e.g. Figure 1 shown, CT3 is the intersection point O 31 and the intersection point O 32 the distance between, CT4 is the intersection point O 41 and the intersection point O 42 the distance between. The air spacing between two lenses refers to the distance between the rear surface of the previous lens and the front surface of the next lens, e.g. Figure 1 As shown, T 34 Intersection point O 32 Intersection point O 41 The distance between them. By constraining the ratio of the center thickness of the third and fourth lenses to the spacing, the manufacturability of the two lenses is ensured, while the influence of the Petzval field curvature of the off-axis field of view of the optical system is also reduced.

[0062] In some embodiments of this disclosure, the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 are further configured such that the optical system 100 satisfies: 0.5 <R R11 *R R12 / f R1 <19, where R R11 R is the radius of curvature of the first surface (object-side surface) of the first refractive lens among the remaining lenses. R12 f is the radius of curvature of the second surface (image-side surface) of the first refractive lens. R1 The focal length of the first refractive lens is given. The first refractive lens is the first refractive lens among the remaining lenses in the direction from the object side to the image side. In some embodiments of this disclosure, the object side of the first refractive lens is convex, that is, the first refractive lens has positive optical power. The spherical aberration in the central field of view under a large aperture of the system is reduced by controlling the radius of curvature and optical power of the first refractive lens.

[0063] In some embodiments of this disclosure, the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 are further configured such that the optical system 100 satisfies: 0.3 < |f4 / f| < 6, where f4 is the focal length of the fourth lens. In third-order aberrations, according to Snell's law, when an object deviates from the optical axis, the imaging rays will be deflected to other positions, resulting in a deviation between the actual image height and the ideal image height. By reasonably controlling the distribution of the optical power of the fourth lens, the influence of the primary aberrations of the third-order distortion in the off-axis field of view of the optical system is balanced, thus minimizing the optical distortion of the system.

[0064] In some embodiments of this disclosure, the optical system 100 further includes an aperture stop STO located on the object side of the first lens 110. Positioning the aperture stop STO on the object side of the first lens allows for a smaller overall size of the optical system 100, making it more suitable for the imaging needs of mobile phones or other portable electronic devices.

[0065] In some embodiments of this disclosure, the optical system 100 further includes a filter 150. The filter 150 is located on the side of the fourth lens 140 near the image plane IS.

[0066] The dispersion difference between superlenses and refracting lenses is significant. The refractive index of a refracting lens depends on the material itself and its Abbe number is positive, while the Abbe number of a superlens, a type of diffractive optical element, is always negative. Its refractive index for short wavelengths is lower than that for long wavelengths, which is the opposite of that of a refracting lens. Therefore, in the optical system design of this application, the focus is on adjusting the optical power of each group of superlenses and refracting lenses to meet the achromatic conditions and achieve good imaging quality. This is much simpler than that of refracting elements that require a large number of lens groups for compensation, and it is also conducive to the design of apochromatic lenses with separate designs.

[0067] Figure 3 This is an example cross-sectional schematic diagram along the optical axis of an optical system provided in an embodiment of this disclosure. Figure 4 for Figure 3 The distortion curve of the provided optical system, Figure 5 for Figure 3 The astigmatism curve of the provided optical system, Figure 6 for Figure 3 The magnification chromatic aberration curve of the provided optical system, Figure 7 for Figure 3 The axial chromatic aberration curve of the provided optical system. For example... Figure 3-7 As shown, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 arranged sequentially from the object side to the image side. Among them, the fourth lens 140 is a superlens, the object side of the first lens 110 (i.e., the first refractive lens) is convex, the optical power of the first lens 110 is positive, and the optical power of the third lens 130 is negative.

[0068] Table 1

[0069] Operating band 400-700nm F-number 2.52 Effective focal length f 7.34mm Field of view 2θ 48° Holographic high 6.698mm System Length 7.2mm

[0070] Table 2

[0071] STO spherical endless -0.5278 S1 aspherical 2.1215 1.25 1.545,56.11 -1.6574 S2 aspherical 16.7482 0.6102 88.8566 S3 aspherical -4.4982 0.8918 1.671,19.1 -1.9504 S4 aspherical -13.3693 1.4318 3.4295 S5 aspherical -30.8309 1.25 1.671,19.1 99.0 S6 aspherical 9.3846 0.8212 3.5868 S7 spherical endless 0.075 1.465,65.77 S8 metasurface endless 0.084 S9 spherical endless 0.21 1.517,64.17 S10 spherical endless 0.576 S11 spherical endless

[0072] Table 3

[0073] S1 0.0189 0.0054 -0.0131 0.0210 -0.0212 0.0136 -0.0055 0.0012 -0.0001 S2 -0.0093 0.0014 -0.0094 0.0122 -0.0090 0.0017 0.0017 -0.0011 0.0002 S3 -0.0082 0.0104 -0.0272 0.0557 -0.0664 0.0411 -0.0090 -0.0024 0.0011 S4 0.0148 -0.0015 0.0529 -0.1428 0.2332 -0.2292 0.1322 -0.0402 0.0047 S5 -0.0365 -0.0043 0.0091 -0.0104 0.0075 -0.0034 0.0009 -0.0001 0.0000 S6 -0.0279 -0.0002 0.0019 -0.0011 0.0004 -0.0001 0.0000 0.0000 0.0000

[0074] As shown in Table 1-3, S1-S6 are the object-side and image-side surfaces of the first lens 110, the second lens 120, and the third lens 130, respectively. S7 and S8 are the object-side and image-side surfaces of the fourth lens 140 (superlens), where the image-side surface of the fourth lens 140 contains a nanostructure layer. S9 and S10 are the object-side and image-side surfaces of the filter 150, and S11 is the image plane IS. Since the first lens 110, the second lens 120, and the third lens 130 are all aspherical surfaces, A4-A20 are the coefficients of the 4th, 6th, and up to 20th order terms of the aspherical surface. The expression used for the aspherical surface is:

[0075]

[0076] Where z is the surface elevation in the direction parallel to the optical axis of the optical system, c is the curvature of the center point of the aspherical surface, k is the quadratic surface constant, i.e., the conic coefficient, and AI correspond to higher-order coefficients.

[0077] In some embodiments, controlling f*EPD / TTL = 2.86 ensures that the overall optical length of the imaging system meets the requirements for miniaturization while maintaining a sufficiently large focal length and aperture, thus achieving good portrait shooting results. M4 / f = 5.31, where f M4 This is the focal length of the fourth lens 140 (superlens). Control T 34 / (CT3+CT4)=0.62, where T 34 Let CT3 be the air gap between the third and fourth lenses, CT4 be the center thickness of the third lens, and CT5 be the center thickness of the fourth lens. By constraining the ratio of the center thicknesses of the third and fourth lenses to the air gap, the manufacturability of the two lenses is ensured, while also reducing the influence of the Pittsvar field curvature in the off-axis field of view of the optical system. Controlling R... R11 *R R12 / f R1 =8.24, meaning the first refractive lens is controlled to have positive optical power. By controlling the radius of curvature and optical power of the first refractive lens, the spherical aberration in the central field of view under a large aperture is reduced. By controlling |f4 / f| = 5.31, the distribution of the optical power of the fourth lens is reasonably controlled, balancing the influence of the third-order primary aberration of the off-axis field of view on the system, thus minimizing the optical distortion of the system.

[0078] The optical power of the second lens 120 and the third lens 130 is constrained to f2*f3 / f = 14.91, where f2 is the focal length of the second lens 120 and f3 is the focal length of the third lens 130. The purpose is to have a compensating effect on the coma and astigmatism in the meridional direction of the off-axis field of view borne by the two lenses. At the same time, the light rays near the central field of view are less deflected when passing through these two lenses, which is beneficial to tolerance sensitivity.

[0079] Figure 8 This is another example cross-sectional schematic diagram of the optical system provided in the embodiments of this disclosure along the optical axis. Figure 9 for Figure 8 The distortion curve of the provided optical system, Figure 10 for Figure 8 The astigmatism curve of the provided optical system, Figure 11 for Figure 8 The magnification chromatic aberration curve of the provided optical system, Figure 12 for Figure 8The axial chromatic aberration curve of the provided optical system. For example... Figure 8-12 As shown, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 arranged sequentially from the object side to the image side. Among them, the third lens 130 is a superlens, the object side of the first lens 110 (i.e., the first refractive lens) is convex, the optical power of the first lens 110 is positive, and the optical power of the fourth lens 140 is negative.

[0080] Table 4

[0081] Operating band 400-700nm F-number 2.35 Effective focal length 7.26mm Field of view 47.6° Holographic high 6.56mm System Length 7.27mm

[0082] Table 5

[0083] STO spherical endless -0.5780 S1 aspherical 2.2609 1.3411 1.545,56.11 -3.2049 S2 aspherical 35.5195 0.5784 56.6308 S3 aspherical -3.3020 1.4 1.671,19.1 4.5029 S4 aspherical -6.0220 0.7683 -23.7632 S5 metasurface endless 0.1 1.465,65.77 S6 spherical endless 1.9611 S7 aspherical 486.7504 0.22 1.545,56.11 -99. S8 aspherical 3.0233 0.2776 -77.2434 S9 spherical endless 0.21 1.517,64.17 S10 spherical endless 0.4135 S11 spherical endless

[0084] Table 6

[0085]

[0086] As shown in Table 4-6, S1-S4 are the object-side and image-side surfaces of the first lens 110 and the second lens 120, respectively; S5 and S6 are the object-side and image-side surfaces of the third lens 130 (superlens), wherein the object-side surface of the third lens 130 contains a nanostructure layer; S7 and S8 are the object-side and image-side surfaces of the fourth lens 140, respectively; S9 and S10 are the object-side and image-side surfaces of the filter 150; and S11 is the image plane IS.

[0087] Since the first lens 110, the second lens 120, and the fourth lens 140 are all aspherical surfaces, the expression used for aspherical surfaces is:

[0088]

[0089] Where z is the surface elevation parallel to the optical axis of the optical system, c is the curvature of the center point of the aspherical surface, k is the quadratic surface constant, i.e., the conic coefficient, and AL correspond to higher-order coefficients.

[0090] In some embodiments, controlling f*EPD / TTL = 3.09 serves two purposes: firstly, to achieve miniaturization of the imaging system's overall length, and secondly, to ensure the system has a sufficiently large effective focal length and aperture, enabling portrait photography and even bokeh effects. M3 / f = 49, where f M3 This is the focal length of the third lens 130 (superlens). Control T 34 / (CT3+CT4)=6.13, where T 34Let CT3 be the air gap between the third and fourth lenses, CT4 be the center thickness of the third lens, and CT5 be the center thickness of the fourth lens. By constraining the ratio of the center thicknesses of the third and fourth lenses to the air gap, the manufacturability of the two lenses is ensured, while also reducing the influence of the Pittsvar field curvature in the off-axis field of view of the optical system. Controlling R... R11 *R R12 / f R1 =18.42, meaning the first refracting lens has positive optical power. By controlling the radius of curvature and optical power of the first refracting lens, the spherical aberration in the central field of view under a large aperture is reduced. |f4 / f| = 0.77. By reasonably controlling the distribution of the optical power of the fourth lens, the influence of the third-order primary aberration of the off-axis field of view on the optical system is balanced, resulting in smaller optical distortion. The fourth lens bears an appropriate amount of distortion to compensate for the distortion caused by the first three lenses, thus improving image quality.

[0091] The design controls the relationship between the focal length of the first lens and the radius of curvature of the object's side surface, as well as the system focal length, i.e., f. R1 *R R11 / f = 1.36, which allows the first lens (i.e. the first refractive lens) to bear the positive optical power while reducing the impact of the central field-of-view spherical aberration on the image quality of the system at large apertures.

[0092] Figure 13 This is another example cross-sectional schematic diagram of the optical system provided in the embodiments of this disclosure along the optical axis. Figure 14 for Figure 13 The distortion curve of the provided optical system, Figure 15 for Figure 13 The astigmatism curve of the provided optical system, Figure 16 for Figure 13 The magnification chromatic aberration curve of the provided optical system, Figure 17 for Figure 13 The axial chromatic aberration curve of the provided optical system. For example... Figure 13-17 As shown, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 arranged sequentially from the object side to the image side. Among them, the second lens 120 is a superlens, the object side of the first lens 110 (i.e., the first refractive lens) is convex, the optical power of the first lens 110 is positive, and the optical power of the fourth lens 140 is negative.

[0093] Table 7

[0094]

[0095]

[0096] Table 8

[0097] STO spherical endless -0.8212 S1 aspherical 2.7887 0.8542 1.545,56.11 -0.6715 S2 aspherical 9.6251 0.2853 -99 S3 aspherical endless 0.15 1.465,65.77 S4 metasurface endless 2.693 S5 aspherical 13.8604 0.6264 1.545,56.11 -99 S6 aspherical 8.5376 1.0996 13.78 S7 aspherical 13.0483 0.7693 1.671,19.1 9.6 S8 aspherical 3.5952 0.1834 -99 S9 spherical endless 0.21 1.517,64.17 S10 spherical endless 0.5287 S11 spherical endless 0

[0098] Table 9

[0099]

[0100] As shown in Table 7-9, S1 and S2 are the object-side and image-side surfaces of the first lens 110 (first refractive lens), S3-S4 are the object-side and image-side surfaces of the second lens 120 (superlens), wherein the image-side surface of the second lens 120 includes a nanostructure layer, S5-S8 are the object-side and image-side surfaces of the third lens 130 and the fourth lens 140, respectively. S9 and S10 are the object-side and image-side surfaces of the filter 150, and S11 is the image plane IS.

[0101] Since the first lens 110, the third lens 130, and the fourth lens 140 are all aspherical, the expression used for aspherical surfaces is:

[0102]

[0103] Where z is the surface elevation parallel to the optical axis of the optical system, c is the curvature of the center point of the aspherical surface, k is the quadratic surface constant, i.e., the conic coefficient, and AK correspond to higher-order coefficients respectively.

[0104] In some embodiments, controlling f*EPD / TTL = 4.12 ensures that the total optical length of the imaging system is small while providing sufficient magnification and a large aperture, thus achieving the effect of shooting portraits. M2 / f = 12.64, where f M2 This is the focal length of the second lens 120 (superlens). Control T 34 / (CT3+CT4)=0.79, where T 34 Let CT3 be the air gap between the third and fourth lenses, CT4 be the center thickness of the third lens, and CT5 be the center thickness of the fourth lens. By constraining the ratio of the center thicknesses of the third and fourth lenses to the air gap, the manufacturability of the two lenses is ensured, while also reducing the influence of the Pittsvar field curvature in the off-axis field of view of the optical system. Controlling R... R11 *R R12 / f R1 =3.90, meaning the first refractive lens is controlled to have positive optical power. By controlling the radius of curvature and optical power of the first refractive lens, the spherical aberration in the central field of view under the large aperture of the system is reduced. |f4 / f| = 0.85. By reasonably controlling the distribution of the optical power of the fourth lens, the influence of the third-order primary aberration of the off-axis field of view of the optical system on the system is balanced, so that the optical distortion of the system is small.

[0105] Figure 18This is another example cross-sectional schematic diagram of the optical system provided in the embodiments of this disclosure along the optical axis. Figure 19 for Figure 18 The distortion curve of the provided optical system, Figure 20 for Figure 18 The astigmatism curve of the provided optical system, Figure 21 for Figure 18 The magnification chromatic aberration curve of the provided optical system, Figure 22 for Figure 18 The axial chromatic aberration curve of the provided optical system. For example... Figure 18-22 As shown, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 arranged sequentially from the object side to the image side. Among them, the first lens 110 is a superlens, the object side of the second lens 120 (i.e., the first refractive lens) is convex, the optical power of the second lens 120 is positive, and the optical power of the fourth lens 140 is negative.

[0106] Table 10

[0107] Operating band 400-700nm F-number 2.04 Effective focal length 7.42mm Field of view 46° Holographic high 6.1mm System Length 7.25mm

[0108] Table 11

[0109]

[0110]

[0111] Table 12

[0112] S3 0.0119 0.0007 0.0004 0.0009 -0.0016 0.0012 -0.0005 0.0001 0.0000 S4 0.0063 -0.0002 -0.0048 0.0086 -0.0086 0.0048 -0.0016 0.0003 0.0000 S5 0.0026 -0.1004 0.4321 -1.1234 1.8475 -1.9343 1.2510 -0.4558 0.0716 S6 0.0080 -0.0011 0.0130 -0.0171 0.0142 -0.0074 0.0024 -0.0005 0.0000 S7 -0.1970 0.1659 -0.0973 0.0399 -0.0112 0.0021 -0.0002 0.0000 0.0000 S8 -0.1379 0.0894 -0.0396 0.0108 -0.0016 0.0000 0.0000 0.0000 0.0000

[0113] As shown in Table 10-12, S1 and S2 are the object-side and image-side surfaces of the first lens 110 (superlens), where the object-side surface of the first lens 110 includes a nanostructure layer. S3-S8 are the object-side and image-side surfaces of the second lens 120 (i.e., the first refractive lens), the third lens 130, and the fourth lens 140, respectively. S9 and S10 are the object-side and image-side surfaces of the filter 150, and S11 is the image plane IS.

[0114] Since the second lens 120, the third lens 130, and the fourth lens 140 are all aspherical, the expression used for aspherical surfaces is:

[0115]

[0116] Where z is the surface elevation in the direction parallel to the optical axis of the optical system, c is the curvature of the center point of the aspherical surface, k is the quadratic surface constant, i.e., the conic coefficient, and AI correspond to higher-order coefficients.

[0117] In some embodiments, controlling f*EPD / TTL = 3.55 ensures that the total optical length of the imaging system is small while providing sufficient magnification and a large aperture, thus achieving the effect of shooting portraits. M1 / f = 23.03, where f M1 This is the focal length of the first lens 110 (superlens). Control T 34 / (CT3+CT4)=1.07, where T 34 Let CT3 be the air gap between the third and fourth lenses, CT4 be the center thickness of the third lens, and CT5 be the center thickness of the fourth lens. By constraining the ratio of the center thicknesses of the third and fourth lenses to the air gap, the manufacturability of the two lenses is ensured, while also reducing the influence of the Pittsvar field curvature in the off-axis field of view of the optical system. Controlling R... R11 *R R12 / f R1 =2.41, meaning the first refractive lens is controlled to have positive optical power. By controlling the radius of curvature and optical power of the first refractive lens, the spherical aberration in the central field of view under the large aperture of the system is reduced. |f4 / f| = 0.97. By reasonably controlling the distribution of the optical power of the fourth lens, the influence of the third-order primary aberration of the off-axis field of view of the optical system on the system is balanced, so that the optical distortion of the system is small.

[0118] The values ​​of the radii of curvature of the two surfaces of the third lens and the radius of curvature of the object surface of the second lens, i.e., R 31 *R 32 / R 21 =8.33, is used to balance coma and astigmatism in the meridional direction of the off-axis field of view, thereby improving image quality. Wherein, R... 31 R is the radius of curvature of the object-side surface of the third lens. 32 R is the radius of curvature of the side surface of the third lens image. 21 Let be the radius of curvature of the object-side surface of the second lens.

[0119] Figure 23 This is another example cross-sectional schematic diagram of the optical system provided in the embodiments of this disclosure along the optical axis. Figure 24 for Figure 23 The distortion curve of the provided optical system, Figure 25 for Figure 23 The astigmatism curve of the provided optical system, Figure 26 for Figure 23 The magnification chromatic aberration curve of the provided optical system, Figure 27 for Figure 23 The axial chromatic aberration curve of the provided optical system. For example... Figure 23-27As shown, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 arranged sequentially from the object side to the image side. The optical system 100 includes two superlenses, wherein the first lens 110 and the second lens 120 are both superlenses, the object side of the third lens 130 (i.e., the first refractive lens) is convex, the optical power of the third lens 130 is positive, and the optical power of the fourth lens 140 is negative.

[0120] Table 13

[0121] Operating band 400-700nm F-number 2.7 Effective focal length 7.42mm Field of view 47.2° Holographic high 6.64mm System Length 7.6mm

[0122] Table 14

[0123]

[0124]

[0125] Table 15

[0126] S5 0.0148 0.0001 0.0054 -0.0091 0.0102 -0.0070 0.0029 -0.0007 0.0001 S6 0.0130 -0.0251 0.1486 -0.4510 0.7998 -0.8646 0.5585 -0.1978 0.0293 S7 -0.0176 -0.0142 0.0176 -0.0142 0.0071 -0.0023 0.0005 -0.0001 0.0000 S8 -0.0219 0.0073 -0.0064 0.0031 -0.0009 0.0002 0.0000 0.0000 0.0000

[0127] As shown in Tables 13-15, S1-S4 are the object-side and image-side surfaces of the first lens 110 (superlens) and the second lens 120 (superlens), respectively. The object-side surface of the first lens 110 and the image-side surface of the second lens 120 contain nanostructure layers. S5-S8 are the object-side and image-side surfaces of the third lens 130 (i.e., the first refractive lens) and the fourth lens 140, respectively. S9 and S10 are the object-side and image-side surfaces of the filter 150, and S11 is the image plane IS.

[0128] Since both the third lens 130 and the fourth lens 140 are aspherical, the expression used for aspherical surfaces is:

[0129]

[0130] Where z is the surface elevation in the direction parallel to the optical axis of the optical system, c is the curvature of the center point of the aspherical surface, k is the quadratic surface constant, i.e., the conic coefficient, and AI correspond to higher-order coefficients.

[0131] In some embodiments, controlling f*EPD / TTL = 2.81 ensures that the total length of the imaging system is small while giving the system a sufficiently large magnification and a large aperture, thereby achieving the effect of shooting portraits.

[0132] Control f M1 / f = 29.50 and f M2 / f = 28.42, where f M1 It is the focal length of the first lens 110 (superlens), f. M2This is the focal length of the second lens 120 (superlens). Control T 34 / (CT3+CT4)=0.99, where T 34 Let CT3 be the air gap between the third and fourth lenses, CT4 be the center thickness of the third lens, and CT5 be the center thickness of the fourth lens. By constraining the ratio of the center thicknesses of the third and fourth lenses to the air gap, the manufacturability of both lenses is ensured, while also reducing the influence of Pitzer field curvature in the off-axis field of view of the optical system. Typically, light emitted from high-energy sources, after passing through optical lenses, forms high-energy bright spots on the image plane or in image space due to Fresnel reflection at the lens surface or scattering through the lens barrel. These bright spots near the image plane are known as ghost images. Under this thickness relationship, the energy of the ghost image reflected between the third and fourth lenses is reduced, improving the final imaging result of the imaging optical path. Controlling R... R11 *R R12 / f R1 =0.98, meaning the first refractive lens has positive optical power. By controlling the radius of curvature and optical power of the first refractive lens, the spherical aberration in the central field of view under a large aperture is reduced. |f4 / f| = 2.56. By reasonably controlling the distribution of the optical power of the fourth lens, the influence of the third-order primary aberration of the off-axis field of view on the system is balanced, resulting in smaller optical distortion. This allows the fourth lens to bear sufficient primary aberration and astigmatism in the meridional and sagittal directions to compensate for the aberrations of the first three lenses, thus improving image quality.

[0133] Figure 28 This is another example cross-sectional schematic diagram of the optical system provided in the embodiments of this disclosure along the optical axis. Figure 29 for Figure 28 The distortion curve of the provided optical system, Figure 30 for Figure 28 The astigmatism curve of the provided optical system, Figure 31 for Figure 28 The magnification chromatic aberration curve of the provided optical system, Figure 32 for Figure 28 The axial chromatic aberration curve of the provided optical system. For example... Figure 28-32 As shown, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 arranged sequentially from the object side to the image side. The optical system 100 includes two superlenses, wherein the object side of the first lens 110 (i.e., the first refractive lens) is convex, the optical power of the first lens 110 is positive, the optical power of the second lens 120 is negative, and the third lens 130 and the fourth lens 140 are both superlenses.

[0134] Table 16

[0135] Operating band 400-700nm F-number 2.99 Effective focal length 7.4mm Field of view 45.4° Holographic high 6.35mm System Length 7.2mm

[0136] Table 17

[0137] STO spherical endless -0.4325 S1 aspherical 1.9197 1.35 1.545,56.11 0.5152 S2 aspherical 2.7257 0.8424 -0.3445 S3 aspherical -1.8395 0.2323 1.671,19.1 0.8957 S4 aspherical -1.9328 2.5904 -0.0171 S5 spherical endless 0.1 1.465,65.77 S6 metasurface endless 1 S7 spherical endless 0.1 1.465,65.77 S8 metasurface endless 0.3576 S9 spherical endless 0.21 1.517,64.17 S10 spherical endless 0.4174 S11 spherical endless 0

[0138] Table 18

[0139]

[0140]

[0141] As shown in Tables 16-18, S1-S4 are the object-side and image-side surfaces of the first lens 110 (i.e., the first refractive lens) and the second lens 120, respectively; S5-S8 are the object-side and image-side surfaces of the third lens 130 (superlens) and the fourth lens 140 (superlens), respectively. The image-side surfaces of the third lens 130 and the fourth lens 140 contain nanostructure layers. S9 and S10 are the object-side and image-side surfaces of the filter 150, and S11 is the image plane IS.

[0142] Since both the first lens 110 and the second lens 120 are aspherical, the expression used for aspherical surfaces is:

[0143]

[0144] Where z is the surface elevation in the direction parallel to the optical axis of the optical system, c is the curvature of the center point of the aspherical surface, k is the quadratic surface constant, i.e., the conic coefficient, and AI correspond to higher-order coefficients.

[0145] In the design, f*EPD / TTL = 2.41 is controlled to keep the overall length of the imaging system small, ensuring miniaturization; at the same time, the system can capture portraits with a sufficiently large effective focal length and aperture, and has a suitable depth of focus.

[0146] Control f M3 / f = 0.88 and f M4 / f = 0.42, where f M3 It is the focal length of the third lens 130 (superlens), f. M4 This is the focal length of the fourth lens 140 (superlens). Control T 34 / (CT3+CT4)=5.00, where T 34Let CT3 be the air gap between the third and fourth lenses, CT4 be the center thickness of the third lens, and CT5 be the center thickness of the fourth lens. By constraining the ratio of the center thicknesses of the third and fourth lenses to the air gap, the manufacturability of both lenses is ensured, while also reducing the influence of Pitzer field curvature in the off-axis field of view of the optical system. Typically, light emitted from high-energy sources, after passing through optical lenses, forms high-energy bright spots on the image plane or in image space due to Fresnel reflection at the lens surface or scattering through the lens barrel. These bright spots near the image plane are known as ghost images. Under this thickness relationship, the energy of the ghost image reflected between the third and fourth lenses is reduced, improving the final imaging result of the imaging optical path. Controlling R... R11 *R R12 / f R1 =0.70, meaning the first refractive lens has positive optical power. By controlling the radius of curvature and optical power of the first refractive lens, the spherical aberration in the central field of view under a large aperture is reduced. |f4 / f| =0.42. By reasonably controlling the distribution of the optical power of the fourth lens, the influence of the third-order primary aberration of the off-axis field of view on the system is balanced, resulting in smaller optical distortion. This allows the fourth lens to bear sufficient primary aberration and astigmatism in the meridional and sagittal directions to compensate for the aberrations of the first three lenses, thus improving image quality.

[0147] Simultaneously control the relationship between the focal length of the first lens and the radius of curvature of the object side surface and the system focal length, i.e., f R1 *R R11 / f = 1.94, which allows the first lens (i.e. the first refractive lens) to bear the positive optical power while reducing the impact of the central field-of-view spherical aberration on the image quality of the system at large apertures.

[0148] This disclosure also provides an imaging device, including the optical system provided in any of the above embodiments; and an image sensor array for generating image data based on light transmitted through the optical system. Examples of the imaging device include, but are not limited to, a camera, which may be a standalone product or a component of other products.

[0149] This disclosure also provides an electronic device that includes the imaging apparatus provided in the above embodiments. Examples of electronic devices include, but are not limited to, desktop computers, server computers, laptop or netbook computers, mobile devices (e.g., tablet computers, cellular or other wireless phones (e.g., smartphones), notebook computers, mobile stations), wearable devices (e.g., glasses, watches), entertainment devices (e.g., entertainment appliances, set-top boxes communicatively coupled to display devices, game consoles), televisions or other display devices, automotive computers, and the like.

[0150] It should be understood that in this specification, the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship or dimensions based on the orientation or positional relationship or dimensions shown in the accompanying drawings. These terms are used only for ease of description and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this disclosure.

[0151] Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0152] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0153] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0154] This specification provides many different implementations or examples that can be used to carry out this disclosure. It should be understood that these different implementations or examples are entirely exemplary. Therefore, the scope of protection of this disclosure should be determined by the scope defined in the appended claims.

Claims

1. An optical system, comprising: a first lens, a second lens, a third lens and a fourth lens arranged in sequence from an object side to an image side, wherein at least one of the first lens, the second lens, the third lens and the fourth lens is a metalens, and the remaining lenses among the first lens, the second lens, the third lens and the fourth lens are refractive lenses, and The first lens, the second lens, the third lens, and the fourth lens are configured such that the optical system satisfies: f / EPD<3.0 ,and HFOV≤24° ,in, f The effective focal length of the optical system is... EPD The entrance pupil diameter of the optical system is [missing information]. HFOV It is half of the maximum field of view of the optical system. The remaining lenses include at least two refractive lenses, and the refractive index difference between any two of the at least two refractive lenses satisfies: 0.01<| n i -n j |<0.2 ,in i and j They are the numbers of the refractive lenses, n i The first in the direction from the object side to the image side i The refractive index of a refractive lens, n j The first in the direction from the object side to the image side j The refractive index of each refracting lens, of which i≠j, Wherein, any of the at least one lens has 0.07mm<t x <1.0mm The thickness, of which x Numbering the superlens. t x The first in the direction from the object side to the image side x The thickness of a superlens The first lens, the second lens, the third lens, and the fourth lens are further configured such that the optical system satisfies: 2mm<f×EPD / TTL<5mm ,in, TTL It is the distance from the first surface of the first lens to the image plane.

2. The optical system according to claim 1, wherein, an object-side surface and an image-side surface of each of the refractive lenses each comprise an aspheric surface.

3. The optical system according to claim 1, wherein, each of the refractive lenses has an Abbe number satisfying 18<V<57, wherein V is the Abbe number.

4. The optical system according to claim 1, wherein, The first lens, the second lens, the third lens, and the fourth lens are further configured such that the optical system satisfies: 0.4<| f Mi / f |<50 ,in, f Mi It is the focal length of any of the superlenses in the at least one lens.

5. The optical system according to claim 1, wherein, any metalens in the at least one lens comprises a base layer and at least one nanostructure layer stacked with the base layer, and at least one of the at least one nanostructure layer comprises a polarization-insensitive periodically arranged structure.

6. The optical system according to any one of claims 1 to 5, wherein, The first lens, the second lens, the third lens, and the fourth lens are further configured such that the optical system satisfies: f×IMGH / N>11mm 2 ,in, IMGH The maximum imaging height of the optical system. N This represents the total number of lenses in the optical system.

7. The optical system according to any one of claims 1 to 5, wherein, The first lens, the second lens, the third lens, and the fourth lens are further configured such that the optical system satisfies: 0.5<T 34 / (CT 3 +CT 4 )<7 ,in, T 34 The air gap between the third and fourth lenses. CT 3 represents the center thickness of the third lens. CT 4 represents the center thickness of the fourth lens.

8. The optical system according to any one of claims 1 to 5, wherein, The first lens, the second lens, the third lens, and the fourth lens are further configured such that the optical system satisfies: 0.5mm<R R11 ×R R12 / f R1 <19mm ,in, R R11 Let be the radius of curvature of the object-side surface of the first refractive lens among the remaining lenses. R R12 Let be the radius of curvature of the image-side surface of the first refracting lens. f R1 The focal length of the first refractive lens is the first refractive lens among the remaining lenses in the direction from the object side to the image side.

9. The optical system according to any one of claims 1 to 5, wherein, The first lens, the second lens, the third lens, and the fourth lens are further configured such that the optical system satisfies: 0.3<| f 4 / f |<6 ,in, f 4 is the focal length of the fourth lens.

10. The optical system according to any one of claims 1 to 5, further comprising an aperture stop, the aperture stop being located on the object side of the first lens.

11. An imaging apparatus, comprising: the optical system according to any one of claims 1-10; and an image sensor array, wherein the image sensor array is configured to generate image data based on light transmitted by the optical system.

12. An electronic device, comprising the imaging apparatus according to claim 11.

Images