Optical system and optical lens

Abstract

The utility model provides an optical system and an optical lens, and relates to the technical field of optical systems. The optical system comprises a first lens group and a second lens group which are sequentially arranged along an incident light path, wherein the first lens group comprises a first refraction lens and a second refraction lens which are sequentially arranged along an incident light path; the focal power of the first refraction lens is negative, and the second refraction lens is a biconvex positive lens; the second lens group comprises a super lens and a third refraction lens which are sequentially arranged along an incident light path; the third refraction lens is a biconvex positive lens; wherein at least the first refracting lens in the first refracting lens, the second refracting lens and the third refracting lens is an aspheric lens. According to the optical system, the number of lenses can be reduced under the condition of ensuring a large field angle and high-quality imaging, so that the system size is reduced, and the production cost is reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of optical systems, and in particular, to an optical system and an optical lens. Background Art

[0002] With the widespread use of vehicles, vehicle-mounted lenses have significantly improved the safety and intelligence of vehicles during driving. Among them, wide-angle high-definition vehicle-mounted lenses can ensure high-resolution imaging while providing a large field of view. Therefore, wide-angle high-definition vehicle-mounted lenses have extremely high requirements for imaging quality under the premise of having a large field of view.

[0003] In the prior art, multiple refractive lenses are usually used to ensure the imaging quality of the vehicle-mounted lens under the condition of a large field of view. However, since such a vehicle-mounted lens uses multiple refractive lenses, it has technical defects of large volume, complex structure and high production cost.

[0004] At present, there is an urgent need for an optical system that can be used in vehicle-mounted lenses and can reduce the number of lenses and system size while ensuring a large field of view and imaging quality, thereby reducing the overall size of the system and production costs. Utility Model Content

[0005] In order to solve the problems in the prior art, the first aspect of the present disclosure provides an optical system, which has a relatively small number of lenses and a relatively small system size while ensuring a large field of view and high-quality imaging. The system includes a first lens group and a second lens group arranged in sequence along an incident light path;

[0006] The first lens group includes a first refractive lens and a second refractive lens arranged in sequence along the incident light path; the first refractive lens has a negative focal length, and the second refractive lens is a biconvex positive lens;

[0007] The second lens group includes a metalens and a third refractive lens arranged in sequence along the incident light path; the third refractive lens is a biconvex positive lens;

[0008] Among the first refractive lens, the second refractive lens and the third refractive lens, at least the first refractive lens is an aspherical lens.

[0009] Optionally, the second lens group further includes a fourth refractive lens;

[0010] Along the incident light path, the fourth refractive lens is located between the super lens and the third refractive lens; and the fourth refractive lens is a biconvex positive lens.

[0011] Optionally, the first refractive lens is an aspherical lens; and the second refractive lens and the third refractive lens are spherical lenses.

[0012] Optionally, the optical system also satisfies:

[0013]

[0014] Where FOV is the maximum field of view of the optical system; F W is the working F number of the optical system; f is the effective focal length of the optical system; TTL is the total optical length of the optical system.

[0015] Optionally, the optical system also satisfies:

[0016]

[0017] Where f is the effective focal length of the optical system; n i is the refractive index of the i-th refractive lens in the optical system, f gi is the focal length of the i-th refractive lens in the optical system, i is a positive integer; t is the ambient temperature.

[0018] Optionally, the optical system also satisfies:

[0019]

[0020] Wherein, TTL is the total optical length of the optical system; D is the entrance pupil diameter of the optical system; BFL is the optical back focal length of the optical system; and f is the effective focal length of the optical system.

[0021] Optionally, the optical system also satisfies:

[0022]

[0023] Among them, f B is the focal length of the second lens group; FOV is the maximum field of view of the optical system; F W is the working F number of the optical system; f is the effective focal length of the optical system.

[0024] Optionally, the optical system also satisfies:

[0025]

[0026] Among them, n F is the refractive index of the third refractive lens in the optical system; EXP is the exit pupil diameter of the optical system; R F D is the curvature radius of the image side of the third refractive lens of the optical system; F is the aperture of the optical system.

[0027] Optionally, the optical system also satisfies:

[0028]

[0029] Wherein, TTL is the total optical length of the optical system; F Wis the working F number of the optical system; D is the entrance pupil diameter of the optical system. FOV is the maximum field of view of the optical system.

[0030] Optionally, the optical system also satisfies:

[0031]

[0032] Among them, K L1 K is the cone coefficient of the object side surface of the first refractive lens in the optical system from the object side to the image side along the optical axis; L2 R is the cone coefficient of the image side surface of the first refractive lens in the optical system from the object side to the image side along the optical axis; L1 R is the radius of curvature of the object side surface of the first refractive lens in the optical system from the object side to the image side along the optical axis; L2 It is the curvature radius of the image side surface of the first refractive lens in the optical system along the direction from the object side to the image side of the optical axis.

[0033] Optionally, the optical system also satisfies:

[0034]

[0035] Among them, CT i is the center thickness of the i-th refractive lens in the optical system, i is a positive integer; TTL is the total optical length of the optical system.

[0036] Optionally, the optical power of the metalens is positive, and the phase of the metalens also satisfies:

[0037]

[0038] in, is the phase distribution of the superlens; r is the distance from any position on the superlens to the center of the superlens.

[0039] Optionally, the optical system further comprises an aperture;

[0040] The aperture stop is located between any two adjacent lenses in the optical system; or, the aperture stop is located on the object side of the first refractive lens.

[0041] Optionally, the aperture is located between the second refractive lens and the metalens.

[0042] The second aspect of the present disclosure provides an optical lens, which is optionally a vehicle-mounted lens. The lens includes an image sensor and an optical system provided by any of the above technical solutions, wherein the image sensor is disposed on an image plane of the optical system.

[0043] The technical solution in this disclosure can produce the following beneficial effects:

[0044] The optical system and optical lens provided according to the embodiments of the present disclosure include a first lens group and a second lens group in sequence along the incident light path; wherein the first lens group includes a first refractive lens and a second refractive lens arranged in sequence along the incident light path; the second lens group includes a super lens and a third refractive lens. The optical focal length of the first refractive lens is negative, and the optical focal lengths of the remaining refractive lenses are all positive, and at least the first refractive lens among the first refractive lens, the second refractive lens, and the third refractive lens is an aspherical lens. The optical system and optical lens provided by the present disclosure can achieve a large field of view and high-quality imaging by using the above-mentioned structure, while reducing the number of lenses used in the system compared to the solution of all-refractive lenses in the prior art, thereby reducing the system size, simplifying the assembly process, and reducing production costs.

[0045] In addition, the optical system can be applied to vehicle-mounted lenses, so that the vehicle-mounted lenses not only have the advantages of miniaturization, lightness and reduced production costs compared to the existing technology solutions, but also have a resolution of 2 million pixels and can ensure imaging quality in an environment with a temperature between -40°C and 105°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The accompanying drawings illustrate embodiments of the present disclosure and together with the following description serve to explain the principles of the present disclosure.

[0047] Figure 1 A schematic diagram of the structure of an optical system provided by an embodiment of the present disclosure is shown;

[0048] Figure 2 The MTF value data curve analysis diagram of the optical system provided in Example 1 is shown at a temperature of 20° C. and spatial frequencies of 42 lp / mm, 83 lp / mm and 167 lp / mm;

[0049] Figure 3 The MTF value data curve analysis diagram of the optical system provided in Example 1 is shown at a temperature of -40°C and spatial frequencies of 42lp / mm, 83lp / mm and 167lp / mm;

[0050] Figure 4 The MTF value data curve analysis diagram of the optical system provided in Example 1 is shown at a temperature of 105° C. and spatial frequencies of 42 lp / mm, 83 lp / mm and 167 lp / mm;

[0051] Figure 5 The field curvature curve S in the sagittal direction and the field curvature curve T in the meridional direction of the optical system provided in Example 1 are shown;

[0052] Figure 6The distortion curves of the optical system provided in Example 1 at various working wavelengths are shown;

[0053] Figure 7 A schematic structural diagram of an optical system provided in Example 2 is shown;

[0054] Figure 8 The MTF value data curve analysis diagram of the optical system provided in Example 2 is shown at a temperature of 20° C. and spatial frequencies of 42 lp / mm, 83 lp / mm and 167 lp / mm;

[0055] Fig. 9 The MTF value data curve analysis diagram of the optical system provided in Example 2 is shown at a temperature of -40°C and spatial frequencies of 42lp / mm, 83lp / mm and 167lp / mm;

[0056] Fig.10 The MTF value data curve analysis diagram of the optical system provided in Example 2 is shown at a temperature of 105° C. and spatial frequencies of 42 lp / mm, 83 lp / mm and 167 lp / mm;

[0057] Fig.11 The field curvature curve S in the sagittal direction and the field curvature curve T in the meridional direction of the optical system provided by Example 2 are shown;

[0058] Fig.12 shows the distortion curve of the optical system provided in Example 2 at each working wavelength;

[0059] Fig.13 A schematic structural diagram of an optical system provided in Example 3 is shown;

[0060] Fig.14 The MTF value data curve analysis diagram of the optical system provided in Example 3 is shown at a temperature of 20° C. and spatial frequencies of 42 lp / mm, 83 lp / mm and 167 lp / mm;

[0061] Fig.15 The MTF value data curve analysis diagram of the optical system provided in Example 3 is shown at a temperature of -40°C and spatial frequencies of 42lp / mm, 83lp / mm and 167lp / mm;

[0062] Fig.16 The MTF value data curve analysis diagram of the optical system provided in Example 3 is shown at a temperature of 105° C. and spatial frequencies of 42 lp / mm, 83 lp / mm and 167 lp / mm;

[0063] Fig.17The field curvature curve S in the sagittal direction and the field curvature curve T in the meridional direction of the optical system provided by Example 3 are shown;

[0064] Fig.18 The distortion curves of the optical system provided in Example 3 at various working wavelengths are shown;

[0065] The reference numerals in the figure represent respectively:

[0066] 10: first lens group; 101: first refractive lens; 102: second refractive lens;

[0067] 20: second lens group; 201: super lens; 202: third refractive lens; 203: fourth refractive lens; 2011: micro-nano structure; 2022: substrate;

[0068] 30: aperture;

[0069] 40: Protective glass;

[0070] 50: filter;

[0071] 60: Image surface. DETAILED DESCRIPTION

[0072] The present disclosure will now be described more fully below with reference to the accompanying drawings, in which various embodiments are shown. However, the present disclosure can be implemented in many different ways and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be exhaustive and complete, and will fully convey the scope of the present disclosure to those skilled in the art. The same reference numerals throughout the text represent the same components. Furthermore, in the accompanying drawings, the thickness, ratios, and sizes of the components are exaggerated for clarity.

[0073] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, "one", "the", "at least one" as used herein do not represent a limitation on quantity, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, "a component" has the same meaning as "at least one component". "At least one" should not be interpreted as being limited to the number "one". "Or" means "and / or". The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0074] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meanings as in the relevant technical context, and unless clearly defined in the specification, these terms are not interpreted as having formal meanings in an idealized or overly formal sense.

[0075] The meaning of “include” or “comprising” specifies properties, quantities, steps, operations, components or a combination thereof, but does not exclude other properties, quantities, steps, operations, components or a combination thereof.

[0076] Embodiments are described herein with reference to cross-sectional views as idealized embodiments. Thus, variations in shape relative to the illustrated diagram are anticipated as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as shown herein, but should include deviations in shape due to, for example, manufacturing. For example, a region shown or described as flat may typically have rough and / or nonlinear features. Moreover, the sharp angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims.

[0077] Hereinafter, exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0078] In one embodiment of the present application, Figure 1 As shown, the object to be measured is located on the left side of the leftmost lens, that is, the object side is located on the left side of the leftmost lens, and the object plane is located on the object side. The image formed by the optical system is located on the right side of the rightmost lens, that is, the image side is located on the right side of the rightmost lens, and the image plane 60 is located on the image side.

[0079] like Figure 1 As shown, the optical system includes a first lens group 10 and a second lens group 20 arranged in sequence along the incident light path; wherein the first lens group 10 includes a first refractive lens 101 and a second refractive lens 102 arranged in sequence along the incident light path. The second lens group 20 includes a metalens 201 and a third refractive lens 202 arranged in sequence along the incident light path.

[0080] The first refractive lens 101 has a negative focal length. The first refractive lens 101 with a negative focal length can diverge the light beam, which is beneficial to expanding the field of view of the system, further optimizing the performance of the optical system, and improving the imaging quality.

[0081] The optical power of the second refractive lens 102 is positive, the object side surface of the second refractive lens 102 is convex toward the object side, and the image side surface of the second refractive lens 102 is convex toward the image side, that is, the second refractive lens 102 is a double convex positive lens.

[0082] The superlens 201 includes a substrate 2012 and a micro-nano structure 2011. The superlens 201 can adaptively adopt a corresponding phase modulation formula to configure various parameters of the micro-nano structure 2011, so that the superlens 201 can achieve corresponding optical performance.

[0083] The third refractive lens 202 has a positive focal length, the object side surface of the third refractive lens 202 is convex toward the object side, and the image side surface of the third refractive lens 202 is convex toward the image side, that is, the third refractive lens 202 is a double convex positive lens.

[0084] Among the first refractive lens 101 , the second refractive lens 102 , and the third refractive lens 202 , at least the first refractive lens 101 is an aspherical lens.

[0085] The optical system provided in the present application can achieve high-quality imaging at a large field of view angle by using one metalens 201 and three refractive lenses, which reduces the number of lenses and the system size compared to the all-refractive lens solution. In addition, due to the advantages of the metalens 201 itself and the reduction in the number of lenses, the overall size and production cost of the vehicle lens using the optical system are reduced.

[0086] In an optional embodiment, the micro-nano structure 2011 is only disposed on the object side of the substrate 2012 .

[0087] In an optional embodiment, the micro-nano structure 2011 is only disposed on the image side of the substrate 2012 .

[0088] In an optional embodiment, the object-side surface of the substrate 2012 and the image-side surface of the substrate 2012 are both provided with micro-nano structures 2011 .

[0089] In an optional embodiment, the micro-nano structure 2011 is a positive micro-nano structure.

[0090] In an optional embodiment, the micro-nano structure 2011 is a negative micro-nano structure.

[0091] In an optional embodiment, the micro-nano structure 2011 is provided with a layer to make the processing technology of the superlens 201 compatible with the existing semiconductor processing technology, which can facilitate the production of the superlens 201.

[0092] In an optional embodiment, the micro-nano structure 2011 is provided with two or more layers, so that the superlens 201 has a larger optical focal length that meets the expected requirements.

[0093] In a specific embodiment, the specific structure of the superlens 201 is: the micro-nano structure 2011 is arranged on the object side of the substrate 2012, and the micro-nano structure 2011 is provided with only one layer, so that the superlens 201 has the expected optical performance and good processability. It should be noted that this is only an exemplary description and cannot be understood as a limitation on the superlens 201. The position of the micro-nano structure 2011 arranged on the substrate 2012, the positive and negative of the micro-nano structure 2011, and the number of layers of the micro-nano structure 2011 can be freely combined as long as the superlens 201 has the expected performance.

[0094] In some embodiments, the object-side surface of the first refractive lens 101 is convex toward the object side, and the image-side surface of the first refractive lens 101 is convex toward the object side, that is, the first refractive lens 101 is a meniscus lens.

[0095] Further, in some embodiments, an edge of a surface of the first refractive lens 101 facing the object side has an inflection point.

[0096] Optionally, the second lens group 20 further includes a fourth refractive lens 203. Along the incident light path, the fourth refractive lens 203 is located between the metalens 201 and the third refractive lens 202, and the fourth refractive lens 203 is a biconvex positive lens. The object side surface of the fourth refractive lens 203 is convex toward the object side, and the image side surface is convex toward the image side, as shown in FIG. Fig.13 shown.

[0097] In the disclosed embodiment and each optional embodiment, the aspheric mirror is mainly used to correct aberrations, which is conducive to obtaining higher imaging quality. In the disclosed embodiment and each optional embodiment, the aspheric mirror is an even-order aspheric mirror, and its surface shape satisfies the following conditions:

[0098]

[0099] Wherein, Z(r) is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of r along the optical axis; c is the curvature of the aspheric surface, where c=1 / R, and R is the radius of curvature of the aspheric surface; k is the cone coefficient; A, B, C, and D correspond to the high-order coefficients of the aspheric mirror, respectively. In the disclosed embodiment, the aspheric mirror is an even-order aspheric lens, which is beneficial to saving materials and space, improving the tolerance of the optical system, reducing or eliminating reflections, and improving the performance of the optical system.

[0100] In an optional embodiment, the first refractive lens 101 is an aspherical lens, the second refractive lens 102 is a spherical lens, and the third refractive lens 202 is a spherical lens. Figure 1 Specifically, the first refractive lens 101 is an aspheric lens with negative optical power, which is beneficial to expanding the field of view of the optical system.

[0101] In an optional embodiment, the second refractive lens 102 is an aspherical lens, the first refractive lens 101 is a spherical lens, and the third refractive lens 202 is a spherical lens.

[0102] In an optional embodiment, the third refractive lens 202 is an aspherical lens, the first refractive lens 101 is a spherical lens, and the second refractive lens 201 is a spherical refractive lens.

[0103] In an optional embodiment, the optical system further includes a fourth refractive lens 203, the fourth refractive lens 203 is an aspherical lens, and the remaining refractive lenses are spherical lenses.

[0104] In an optional embodiment, the first refractive lens 101 and the second refractive lens 102 are both aspherical lenses, and the third refractive lens 202 is a spherical lens.

[0105] In an optional embodiment, the first refractive lens 101 and the third refractive lens 202 are both aspherical lenses, and the second refractive lens 102 is a spherical lens.

[0106] In an optional embodiment, the second refractive lens 102 and the third refractive lens 202 are both aspherical lenses, and the first refractive lens 101 is a spherical lens.

[0107] In an optional embodiment, the optical system further includes a fourth refractive lens 203, the fourth refractive lens 203 is an aspherical lens, and any one of the first refractive lens 101, the second refractive lens 102 and the third refractive lens 202 is an aspherical lens.

[0108] In an optional embodiment, the first refractive lens 101 , the second refractive lens 102 and the third refractive lens 202 are all aspherical lenses.

[0109] In an optional embodiment, the optical system further includes a fourth refractive lens 203, the fourth refractive lens 203 is an aspherical lens, and any two of the first refractive lens 101, the second refractive lens 102 and the third refractive lens 202 are aspherical lenses.

[0110] In an optional embodiment, the optical system further includes a fourth refractive lens 203, and the first refractive lens 101, the second refractive lens 102, the third refractive lens 202 and the fourth refractive lens 203 are all aspherical lenses.

[0111] In the embodiment of the present disclosure, the metasurface phase distribution of the metalens 201 satisfies the following conditions:

[0112]

[0113] Wherein, r is the distance from the center of the superlens 201 to any position on the superlens, and λ is the operating wavelength of the superlens 201. is any phase related to the operating wavelength of the superlens 201. (x, y) is the coordinate of any position on the superlens 201. m1 is the focal length of the super lens 201. i and b i are real coefficients.

[0114] The optical system provided in this application meets the following requirements:

[0115]

[0116] Among them, FOV (Field of View, referred to as FOV) is the maximum field of view of the optical system. W is the working F number of the optical system. f is the effective focal length of the optical system, and the dimension of f is a length unit, such as millimeters. TTL (Total Track Length, abbreviated as TTL) is the total optical length of the optical system. In the present application, TTL is the distance from the object side of the first refractive lens 101 to the image plane 60 on the optical axis, and the dimension of TTL is a length unit, such as millimeters. In the embodiment of the present disclosure, the upper limit of the conditional expression is to ensure that the optical system has a sufficient amount of light input; the lower limit is to ensure that the optical system has a sufficiently large incident angle and has the ability to be miniaturized.

[0117] In a preferred embodiment, the optical system provided by the present application satisfies:

[0118]

[0119] In the application, the upper limit of the conditional expression is to ensure that the optical system has a sufficient amount of light entering; the lower limit of the conditional expression is to ensure that the optical system has a sufficiently large incident angle and has the ability to be miniaturized.

[0120] Furthermore, the optical system provided by the present application also satisfies:

[0121]

[0122] Where f is the effective focal length of the optical system. gi is the focal length of the i-th refractive lens in the optical system, n i is the refractive index of the i-th refractive lens in the optical system along the incident light path, dn i / dt is the change in the refractive index of the i-th refractive lens in the optical system as the ambient temperature changes, and i is a positive integer. For example, n1 is the refractive index of the first refractive lens 101 in the optical system along the incident light path, and dn1 / dt is the change in the refractive index of the first refractive lens 101 in the optical system as the ambient temperature changes. f and f gi The dimensions of are the same, both are length units, such as millimeters. t is the ambient temperature. According to the above conditional formula, when i is 3, it means that the conditional formula is applicable to an optical system containing 3 refractive lenses, such as Figure 1 or Figure 7 As shown in FIG. 1 , the optical system includes a first refractive lens 101, a second refractive lens 102, a super lens 201, and a third refractive lens 202. When i is 4, it means that the conditional expression is applicable to an optical system including four refractive lenses, such as Fig.13 As shown, the optical system includes a first refractive lens 101, a second refractive lens 102, a super lens 201, a fourth refractive lens 203, and a third refractive lens 202 arranged in sequence along the optical path. In the embodiment of the present disclosure, the upper limit value of the above conditional formula is to compensate for the influence of temperature on the imaging of the optical system and improve the temperature adaptability of the optical system so that the optical system can still ensure high-quality imaging in environments with different temperatures. The lower limit value is to avoid the influence of temperature overcompensation on the imaging of the optical system.

[0123] Furthermore, the optical system also satisfies:

[0124]

[0125] Wherein, TTL is the total optical length of the optical system, BFL (Back Focal Length, abbreviated as BFL) is the optical back focal length of the optical system, and in the present application, BFL is the distance between the image side surface of the third refractive lens 202 and the image plane 60 on the optical axis. In the present application, the dimensions of BFL and TTL are both length units, such as millimeters. D is the entrance pupil diameter of the optical system. f is the effective focal length of the optical system, and the dimension of f is a length unit, such as millimeters. The upper limit of the above conditional formula is to ensure that the optical system has sufficient optical back focal length to facilitate the assembly of the optical system. The lower limit of the above conditional formula is to ensure that the optical system has a sufficiently large entrance pupil diameter, thereby ensuring that the optical system has sufficient light intake.

[0126] In this application, the optical system also satisfies:

[0127]

[0128] Among them, f B is the focal length of the second lens group 20, f is the effective focal length of the optical system, and f and f BThe dimensions of F and F are the same, both are length units, such as millimeters. FOV is the maximum field of view of the optical system. W is the working F number of the optical system. The upper limit of the above conditional expression can prevent the focal length of the second lens group 20 from being too large. If the focal length of the second lens group 20 is too large, the imaging quality of the optical system will be reduced. The lower limit of the above conditional expression is to ensure that the optical system has a sufficient amount of light input, so as to ensure that the image formed by the optical system is brighter and clearer.

[0129] Furthermore, the optical system provided by the present application also satisfies:

[0130]

[0131] Among them, n F is the refractive index of the third refractive lens 202 in the optical system. EXP (Exit Pupil, referred to as EXP) is the exit pupil diameter of the optical system, in millimeters. F D is the curvature radius of the image side surface of the third refractive lens 202 of the optical system, in millimeters. F is the aperture of the optical system, in millimeters. The value of the above conditional expression is between 0.01 and 0.04, which is used to constrain the CRA (Chief Ray Angle, CRA for short) range of the optical system, and can ensure that the optical system and the corresponding image sensor have a good match.

[0132] In this application, the optical system also satisfies:

[0133]

[0134] Wherein, TTL is the total optical length of the optical system, and the dimension of TTL is length unit, such as millimeter. W is the working F number of the optical system. D is the entrance pupil diameter of the optical system, in millimeters. FOV is the maximum field of view of the optical system. The upper limit of the above conditional formula can control the total length of the optical system and avoid the volume of the optical system being too large. The lower limit of the above conditional formula can ensure that the size of the imaging area on the image plane 60 of the optical system and the field of view angle range of the optical system meet the preset requirements. This conditional formula ensures that the optical system can be miniaturized, and at the same time, this conditional formula ensures that the size of the imaging area on the image plane of the optical system meets the preset requirements.

[0135] In this application, the optical system also satisfies:

[0136]

[0137] Among them, K L1 is the cone coefficient of the object side surface of the first refractive lens 101, K L2is the cone coefficient of the image side surface of the first refractive lens 101. L1 is the radius of curvature of the object side surface of the first refractive lens 101, R L2 is the curvature radius of the image side surface of the first refractive lens 101, R L1 , R L2 The dimensions of are the same, both are length units, such as millimeters. The upper limit of the above conditional expression can ensure that the first refractive lens 101 in the optical system fully exerts the effect of aspheric aberration correction. The lower limit of the above conditional expression can ensure that the first refractive lens 101 in the optical system has a negative focal length that meets expectations.

[0138] Furthermore, the optical system provided by the present application also satisfies:

[0139]

[0140] Among them, CT i is the center thickness of the i-th refractive lens in the optical system, in millimeters, i is a positive integer, i is 3 or 4. According to the above conditional formula, when i is 3, it means that the conditional formula is applicable to an optical system containing 3 refractive lenses, such as Figure 1 or Figure 7 As shown, the optical system includes a first refractive lens 101, a second refractive lens 102, a super lens 201 and a third refractive lens 202. That is, the sum of the center thickness CT1 of the first refractive lens 101, the center thickness CT2 of the second refractive lens 102, and the center thickness CT3 of the third refractive lens 202. When i is 4, it means that the conditional expression is applicable to an optical system including four refractive lenses, such as Fig.13 As shown, the optical system includes a first refractive lens 101, a second refractive lens 102, a super lens 201, a fourth refractive lens 203 and a third refractive lens 202 which are sequentially arranged along the optical path. That is, the sum of the center thickness CT1 of the first refractive lens 101, the center thickness CT2 of the second refractive lens 102, the center thickness CT3 of the fourth refractive lens 203, and the center thickness CT4 of the third refractive lens 202. It should be noted that for this conditional expression, when i is equal to 4, although i is greater than 3, i cannot be set to 3 at this time, that is, i can only take the maximum value it can take. TTL is the total optical length of the optical system, CT i The dimensions of , TTL are all length units, such as millimeters. The upper limit of the above conditional formula can ensure that the thickness of the air space in the optical system meets the expected requirements, thereby leaving enough space for balancing aberrations. The lower limit of the above conditional formula can ensure the thickness of each refractive lens, which is beneficial to reduce the field curvature of the system and improve the imaging quality of the optical system.

[0141] In the present application, the optical system provides a metalens 201 having positive optical power, and the phase distribution of the metalens 201 is Also meets:

[0142]

[0143] in, is the phase of the superlens 201, The unit is rad. is the phase change of the superlens 201. r is the distance from any position on the superlens 201 to the center of the superlens 201, and the unit of r is millimeter. dr is the change in the distance from any position on the superlens 201 to the center of the superlens 201. The above conditional formula reflects the phase gradient of the superlens 201. It should be noted that in order to make the superlens 201 have a larger positive optical focal length, the superlens 201 requires a larger phase gradient, that is, there are higher requirements on the shape of the micro-nano structure 2011 of the superlens 201. However, the greater the optical focal length provided by the superlens 201 in the optical system, the more complicated the processing of the micro-nano structure 201 of the superlens 201 will usually be. Therefore, the superlens 201 with a larger optical focal length will usually have a larger processing error.

[0144] The upper limit of the above conditional expression can avoid the optical focal length of the metalens 201 being too large. If the optical focal length of the metalens 201 is too large, excessive chromatic aberration will occur, which is not conducive to improving the imaging quality of the optical system, and will also increase the processing difficulty and processing error of the metalens 201. The lower limit of the above conditional expression is to avoid the optical focal length of the metalens 201 in the optical system being too small, that is, the lower limit can ensure that the metalens 201 can bear a certain optical focal length in the optical system, so that the optical system can reduce or even balance chromatic aberration or other aberrations, and improve the imaging quality of the optical system.

[0145] In a preferred embodiment, the phase distribution of the metalens 201 is Also meets:

[0146]

[0147] The value of the conditional expression is between 35 rad / mm and 175 rad / mm, which can ensure that the superlens 201 has a relatively suitable optical focal length.

[0148] In an optional embodiment, the optical system further includes an aperture 30 , which is mainly used to control the amount of light entering the optical system. The aperture 30 is located between any two adjacent lenses in the optical system; or, the aperture 30 is located on the object side of the first refractive lens 101 .

[0149] Regarding the setting position of the aperture, when the optical system does not include the fourth refractive lens 203, the setting position of the aperture satisfies any of the following conditions:

[0150] (1) The aperture 30 is disposed on the object side of the first refractive lens 101 , that is, there is a preset distance between the aperture 30 and the first refractive lens 101 .

[0151] (2) The aperture stop 30 is disposed on the object-side surface of the first refractive lens 101 .

[0152] (3) The aperture stop 30 is provided on the image-side surface of the first refractive lens 101 .

[0153] (4) The aperture 30 is provided between the first refractive lens 101 and the second refractive lens 102 .

[0154] (5) The aperture stop 30 is disposed on the object-side surface of the second refractive lens 102 .

[0155] (6) The aperture stop 30 is provided on the image-side surface of the second refractive lens 102 .

[0156] (7) The aperture 30 is provided between the second refractive lens 102 and the super lens 201 .

[0157] (8) The aperture 30 is provided on the object side surface of the super lens 201 .

[0158] (9) The aperture 30 is provided on the image-side surface of the superlens 201 .

[0159] (10) The aperture 30 is provided between the super lens 201 and the third refractive lens 202 .

[0160] (11) The aperture 30 is disposed on the object-side surface of the third refractive lens 202 .

[0161] Regarding the setting position of the aperture, when the optical system further includes a fourth refractive lens 203, the setting position of the aperture satisfies any of the following conditions:

[0162] (1) The aperture 30 is disposed on the object side of the first refractive lens 101 , that is, there is a preset distance between the aperture 30 and the first refractive lens 101 .

[0163] (2) The aperture stop 30 is disposed on the object-side surface of the first refractive lens 101 .

[0164] (3) The aperture stop 30 is provided on the image-side surface of the first refractive lens 101 .

[0165] (4) The aperture 30 is provided between the first refractive lens 101 and the second refractive lens 102 .

[0166] (5) The aperture stop 30 is disposed on the object-side surface of the second refractive lens 102 .

[0167] (6) The aperture stop 30 is provided on the image-side surface of the second refractive lens 102 .

[0168] (7) The aperture 30 is provided between the second refractive lens 102 and the super lens 201 .

[0169] (8) The aperture 30 is provided on the object side surface of the super lens 201 .

[0170] (9) The aperture 30 is provided on the image-side surface of the superlens 201 .

[0171] (10) The aperture 30 is provided between the super lens 201 and the fourth refractive lens 203 .

[0172] (11) The aperture 30 is disposed on the object-side surface of the fourth refractive lens 203 .

[0173] (12) The aperture stop 30 is provided on the image-side surface of the fourth refractive lens 203 .

[0174] (13) The aperture 30 is provided between the fourth refractive lens 203 and the third refractive lens 202 .

[0175] (14) The aperture 30 is disposed on the object-side surface of the third refractive lens 202 .

[0176] In an optional embodiment, a protective glass 40 is further disposed between the second lens group 20 and the image side 60 to protect the image sensor of the optical lens corresponding to the optical system disposed on the image plane 60 of the optical system.

[0177] In an optional embodiment, the material of the protection glass 40 is silicon.

[0178] In an optional embodiment, a filter 50 is further provided between the protective glass 40 and the image plane 60 to filter stray light outside the working band contained in the light beam, and can filter out interference caused by light in non-working bands, thereby improving imaging quality.

[0179] According to the optical system provided by the present application, the total optical length TTL of the system is less than 25 mm, and the maximum field of view angle is greater than 120°. Therefore, the optical system provided by the present application realizes the miniaturization of the optical system while ensuring a large field of view angle. At the same time, the central field of view of the above-mentioned optical system is greater than 0.3 at the cutoff frequency of 166.7lp / mm, which means that the optical system provided by the present disclosure can meet the resolution of 2 million pixels. In addition, the above-mentioned optical system has a good effect of athermalization at -40°C to 105°C, which makes the optical system have strong temperature adaptability and can also achieve high-definition imaging at a temperature of -40°C to 105°C.

[0180] The following are specific embodiments provided by the present disclosure:

[0181] Example 1

[0182] Figure 1 Schematic diagram of the structure of an optical system provided by this embodiment is shown. In embodiment 1, the optical system includes a first refractive lens 101, a second refractive lens 102, an aperture 30, a super lens 201, a third refractive lens 202, a protective glass 40 and a filter 50 arranged in sequence along the incident light path. Among them, the first refractive lens 101 is an even-order aspheric lens, the other refractive lenses are spherical lenses, and the micro-nano structure 2011 is arranged on the object side of the substrate 2012. The parameters of the optical system are shown in Table 1-1.

[0183] Table 1-1 System parameters of the optical system provided in Example 1

[0184] parameter data Total optical length (TTL) 20.755mm Maximum field of view FOV (2ω) 120.16° F-number 1.56 Effective focal length (f) 4.46mm Working band Visible light (435nm-656nm)

[0185] As can be seen from Table 1-1, the F number of the optical system in this embodiment is 1.56, and the optical system has a large amount of light intake, ensuring excellent imaging quality. At the same time, the total length of the optical system is only 20.755 mm, which fully meets the requirements of the optical system for miniaturization.

[0186] Each surface in the optical system is numbered from the object side to the image side, and the parameters of the curvature radius / thickness and material of each lens surface in the optical system are summarized to obtain Table 1-2.

[0187] Table 1-2 Surface parameters of each lens in the optical system provided in Example 1

[0188]

[0189]

[0190] Referring to Table 1-2, surface 1 is the object side surface of the first refractive lens 101, and its radius of curvature is 2.99 mm, and the distance between it and surface 2 is 2.03 mm. The refractive index (ND) and dispersion (VD) of the material between it and surface 2 are 1.69 and 53.0, respectively. Surface 2 is the image side surface of the first refractive lens 101, and its radius of curvature is 1.46 mm, and the distance between it and surface 3 is 3.09 mm. The material between surface 2 and surface 3 is air. Surface 3 is the object side surface of the second refractive lens 102, and its radius of curvature is 17.3 mm, and the distance between it and surface 4 is 6.20 mm. The refractive index (ND) and dispersion (VD) of the material between it and surface 4 are 1.78 and 37.1, respectively. Surface 4 is the image side surface of the second refractive lens 102, and its radius of curvature is -7.05 mm, and the distance between it and surface 5 is 0.32 mm. The material between surface 4 and surface 5 is air. Surface 5 is an aperture, and the radius of curvature of surface 5 is infinite. Therefore, surface 5 is a plane, and the distance between it and surface 6 is 1.03 mm, and the material between it and surface 6 is air. Micro-nano structure 2011 is only provided on the object side of substrate 2012, and therefore surface 6 is recorded as a super surface. Surface 6 is the object side of super lens 201, and its radius of curvature is infinite. Therefore, surface 6 is a plane, and the distance between it and surface 7 is 0.725 mm, and the refractive index (ND) and dispersion (VD) of the material between it and surface 7 are 1.46 and 67.8 respectively. Surface 7 is the image side of super lens 201, and its radius of curvature is infinite. Therefore, surface 7 is a plane, and the distance between it and surface 8 is 0.03 mm, and the material between it and surface 8 is air. Surface 8 is the object side surface of the third refractive lens 202, and its radius of curvature is 5.95 mm. The distance between it and surface 9 is 4.99 mm. The refractive index (ND) and dispersion (VD) of the material between it and surface 9 are 1.57 and 71.3, respectively. Surface 9 is the image side surface of the third refractive lens 202, and its radius of curvature is -15.9 mm. The distance between it and surface 10 is 1.39 mm. The material between it and surface 10 is air. Surface 10 is the object side surface of the protective glass 40, and its radius of curvature is infinite. Therefore, surface 10 is a plane. The distance between it and surface 11 is 0.40 mm. The refractive index (ND) and dispersion (VD) of the material between it and surface 10 are 1.52 and 54.5, respectively. Surface 11 is the image side surface of the protective glass 40, and its radius of curvature is infinite. Therefore, surface 11 is a plane. The distance between it and surface 12 is 0.05 mm. The material between it and surface 12 is air. Surface 12 is the object side surface of filter 50, and its curvature radius is infinite. Therefore, surface 12 is a plane, and the distance between it and surface 13 is 0.40 mm. The refractive index (ND) and dispersion (VD) of the material between it and surface 13 are 1.52 and 54.5 respectively.Surface 13 is the image side surface of filter 50, and its curvature radius is infinite, so surface 13 is a plane, and the distance between it and surface 14 is 0.10 mm, and the material between it and surface 14 is air. Surface 14 is image surface 60, and its curvature radius is infinite, so surface 14 is a plane.

[0191] Surface 1 and surface 2 are even-order aspheric surfaces. After summarizing their parameters, we get Table 1-3.

[0192] Table 1-3 Coefficients of the even-order aspheric surface of the optical system provided in Example 1

[0193]

[0194] Figures 2 to 4 The MTF (Modulation Transfer Function, MTF for short) field of view curve of the optical system at temperatures of 20°C, -40°C and 105°C are shown respectively. In the figure, the horizontal axis is the x-axis field of view, and its unit is degree; the vertical axis is the MTF value. Figures 2 to 4 The sagittal curve S1 and meridional curve T1 of MTF varying with field of view at 42lp / mm spatial frequency, the sagittal curve S2 and meridional curve T2 of MTF varying with field of view at 83lp / mm spatial frequency, and the sagittal curve S3 and meridional curve T3 of MTF varying with field of view at 167lp / mm spatial frequency are listed respectively.

[0195] Depend on Figure 2 It can be seen that under the condition of 20℃, the MTF value of the optical system in the full field of view at a spatial frequency of 42lp / mm is greater than 0.64, and the imaging quality of the optical system under the condition of a large field of view is extremely high. Under the condition of 20℃, the MTF value of the optical system in the full field of view at a spatial frequency of 83lp / mm is greater than 0.35, which also proves that the optical system has a high imaging quality under the condition of a large field of view. Under the condition of 20℃, the MTF value of the optical system in the 0.9 field of view (54.07°) at a spatial frequency of 167lp / mm is greater than 0.2, which proves that the optical system can process complex images under the condition of a large field of view while also having good imaging quality.

[0196] Depend on Figure 3It can be seen that under the condition of -40℃, the MTF value of the optical system in the full field of view at a spatial frequency of 42lp / mm is greater than 0.65, and the imaging quality of the optical system under the condition of a large field of view is extremely high. Under the condition of -40℃, the MTF value of the optical system in the full field of view at a spatial frequency of 83lp / mm is greater than 0.34, which also proves that the optical system has excellent imaging quality under the condition of a large field of view. Under the condition of -40℃, the MTF value of the optical system in the 0.9 field of view (54.07°) at a spatial frequency of 167lp / mm is greater than 0.2, and the imaging quality of the optical system is better. Overall Figure 2 and Figure 3 , the imaging quality of the optical system at -40℃ is almost the same as that at 20℃.

[0197] Depend on Figure 4 It can be seen that under the condition of 105℃, the MTF value of the optical system in the full field of view at a spatial frequency of 42lp / mm is greater than 0.63, and the imaging quality of the optical system under the condition of a large field angle is extremely high. Under the condition of 105℃, the MTF value of the optical system in the full field of view at a spatial frequency of 83lp / mm is greater than 0.34, which also proves that the optical system has a high imaging quality under a large field angle. Under the condition of 105℃, the MTF value of the optical system in the 0.9 field of view (54.07°) at a spatial frequency of 167lp / mm is greater than 0.2, and the imaging quality of the optical system is good.

[0198] comprehensive Figures 2 to 4 , at -40℃ to 105℃, the fluctuation of the MTF of the optical system is small at the same spatial frequency, indicating that the optical system in this embodiment has good athermal effect and strong temperature adaptability, and high-definition imaging can be achieved under the conditions of -40℃ to 105℃.

[0199] Figure 5 The field curvature of the optical system under this embodiment is shown. Figure 5 The horizontal axis represents the field curvature in millimeters, and the vertical axis represents the field angle in degrees. Figure 5 Middle Curve T 11 is the field curvature of visible light with a wavelength of 656nm in the meridian direction, Figure 5 Middle Curve S 11 The maximum field curvature of the optical system in the meridian direction is 0.028mm, and the maximum field curvature in the sagittal direction is 0.021mm under the visible light with a wavelength of 656nm. Figure 5 Middle Curve T 12 is the field curvature of visible light with a wavelength of 587nm in the meridian direction, curve S 12The maximum field curvature of the optical system in the meridional direction is 0.022mm, and the maximum field curvature in the sagittal direction is 0.021mm under the visible light with a wavelength of 587nm. Figure 5 Middle Curve T 13 is the field curvature of visible light with a wavelength of 546nm in the meridian direction, curve S 13 The maximum field curvature of the optical system in the meridional direction is 0.027mm, and the maximum field curvature in the sagittal direction is 0.023mm under the visible light with a wavelength of 546nm. Figure 5 Middle Curve T 14 is the field curvature of visible light with a wavelength of 486nm in the meridian direction, curve S 14 The maximum field curvature of the optical system in the meridional direction is 0.035mm, and the maximum field curvature in the sagittal direction is 0.022mm under the visible light with a wavelength of 486nm. Figure 5 Middle Curve T 15 is the field curvature of visible light with a wavelength of 435nm in the meridian direction, curve S 15 is the field curvature of visible light with a wavelength of 435nm in the meridional direction. Under visible light with a wavelength of 435nm, the maximum field curvature of the optical system in the meridional direction is 0.045mm, and the maximum field curvature in the sagittal direction is 0.028mm. Figure 5 It can be seen that the field curvature of the optical system provided in Example 1 is relatively small, meeting the requirements for field curvature in the excellent imaging quality standard.

[0200] Figure 6 The distortion curves of the optical system provided in Example 1 at wavelengths of 656nm, 587nm, 546nm, 486nm and 435nm are shown, with the horizontal axis representing the degree of distortion in percentage and the vertical axis representing the field of view in degrees. Figure 6 A total of five curves are shown, but the differences between the five curves are very small, resulting in the five curves almost overlapping, so the five curves are not distinguished. ) It can be seen that the maximum distortion of the optical system in the full field of view under this embodiment is -62%.

[0201] Example 2

[0202] Figure 7The schematic diagram of the structure of an optical system provided by this embodiment is shown. In embodiment 2, the optical system includes a first refractive lens 101, a second refractive lens 102, an aperture 30, a super lens 201, a third refractive lens 202, a protective glass 40 and a filter 50 arranged in sequence along the incident light path. Among them, the first refractive lens 101 is an even-order aspheric lens, the other refractive lenses are spherical lenses, and the micro-nano structure 2011 is arranged on the object side of the substrate 2012. The parameters of the optical system are shown in Table 2-1.

[0203] Table 2-1 System parameters of the optical system provided in Example 2

[0204] parameter data Total optical length (TTL) 22.985mm Maximum field of view FOV (2ω) 120° F-number 1.58 Effective focal length (f) 4.35mm Working band Visible light (435nm-656nm)

[0205] As can be seen from Table 2-1, the F number of the optical system in this embodiment is 1.58, and the optical system has a large amount of light intake, ensuring excellent imaging quality. At the same time, the total length of the optical system is only 22.985 mm, which fully meets the requirements of the optical system for miniaturization.

[0206] The surfaces in the optical system are numbered from the object side to the image side, and the parameters of the curvature radius / thickness and material of each lens surface in the optical system are summarized to obtain Table 2-2. The analysis of each surface in Table 2-2 can refer to Example 1 and will not be analyzed again here.

[0207] Table 2-2 Surface parameters of each lens in the optical system provided by Example 2

[0208]

[0209]

[0210] After summarizing the surface parameters of aspheric mirrors, we obtain Table 2-3.

[0211] Table 2-3 Coefficients of the even-order aspheric surfaces of the optical system provided in Example 2

[0212]

[0213] Figures 8 to 10 The MTF field of view curve of the optical system at temperatures of 20°C, -40°C and 105°C is shown, where the horizontal axis is the x-axis field of view, the unit of which is degree; the vertical axis is the MTF value. Figures 8 to 10 The sagittal curve S1 and meridional curve T1 of MTF varying with field of view at 42lp / mm spatial frequency, the sagittal curve S2 and meridional curve T2 of MTF varying with field of view at 83lp / mm spatial frequency, and the sagittal curve S3 and meridional curve T3 of MTF varying with field of view at 167lp / mm spatial frequency are listed respectively.

[0214] Depend on Figure 8 It can be seen that under the condition of 20℃, the MTF value of the optical system in the full field of view at a spatial frequency of 42lp / mm is greater than 0.49, and the imaging quality of the optical system under the condition of a large field of view is extremely high. Under the condition of 20℃, the MTF value of the optical system in the full field of view at a spatial frequency of 83lp / mm is greater than 0.22, which also proves that the optical system has a high imaging quality under the condition of a large field of view. Under the condition of 20℃, the MTF value of the optical system in the 0.9 field of view (54°) at a spatial frequency of 167lp / mm is greater than 0.18, which proves that the optical system can process complex images under the condition of a large field of view while also having good imaging quality.

[0215] Depend on Fig. 9 It can be seen that under the condition of -40°C and the spatial frequency of 42lp / mm, the MTF value of the optical system in the full field of view is greater than 0.49, and the imaging quality of the optical system under the condition of a large field of view is extremely high. Under the condition of -40°C and the spatial frequency of 83lp / mm, the MTF value of the optical system in the full field of view is greater than 0.24, which also proves that the optical system has excellent imaging quality under the condition of a large field of view. Under the condition of -40°C and the spatial frequency of 167lp / mm, the MTF value of the optical system in the 0.9 field of view (54°) is greater than 0.18, and the imaging quality of the optical system is better. Overall Figure 8 and Fig. 9 , the imaging quality of the optical system at -40℃ is almost the same as that at 20℃.

[0216] Depend on Fig.10 It can be seen that under the condition of 105℃ and the spatial frequency of 42lp / mm, the MTF value of the optical system in the whole field of view is greater than 0.48, and the imaging quality of the optical system under the condition of large field of view is extremely high. Under the condition of 105℃ and the spatial frequency of 83lp / mm, the MTF value of the optical system in the whole field of view is greater than 0.22. Under the condition of 105℃ and the spatial frequency of 167lp / mm, the MTF value of the optical system in the 0.9 field of view (54°) is greater than 0.18, and the imaging quality of the optical system is good.

[0217] comprehensive Figures 8 to 10 , at -40℃~105℃, the fluctuation of MTF of the optical system is small at the same spatial frequency, indicating that the optical system in this embodiment has good athermal effect and strong temperature adaptability, and high-definition imaging can be achieved under the conditions of -40℃ to 105℃.

[0218] Fig.11 The field curvature of the optical system under this embodiment is shown. Fig.11 The horizontal axis represents the field curvature in millimeters, and the vertical axis represents the field angle in degrees. Fig.11 Middle Curve T 21 is the field curvature of visible light with a wavelength of 656nm in the meridian direction, Fig.11 Middle Curve S 21 The maximum field curvature of the optical system in the meridian direction is 0.043mm, and the maximum field curvature in the sagittal direction is 0.032mm under the visible light with a wavelength of 656nm. Fig.11 Middle Curve T 22 is the field curvature of visible light with a wavelength of 587nm in the meridian direction, curve S 22 The maximum field curvature of the optical system in the meridional direction is 0.027 mm, and the maximum field curvature in the sagittal direction is 0.029 mm under the visible light with a wavelength of 587 nm. Fig.11 Middle Curve T 23 is the field curvature of visible light with a wavelength of 546nm in the meridian direction, curve S 23 The maximum field curvature of the optical system in the meridional direction is 0.025 mm, and the maximum field curvature in the sagittal direction is 0.026 mm under the visible light with a wavelength of 546 nm. Fig.11 Middle Curve T 24 is the field curvature of visible light with a wavelength of 486nm in the meridian direction, curve S 24 The maximum field curvature of the optical system in the meridional direction is 0.02mm, and the maximum field curvature in the sagittal direction is 0.023mm under the visible light with a wavelength of 486nm. Fig.11 Middle Curve T 25 is the field curvature of visible light with a wavelength of 435nm in the meridian direction, curve S 25 is the field curvature of visible light with a wavelength of 435nm in the meridional direction. Under visible light with a wavelength of 435nm, the maximum field curvature of the optical system in the meridional direction is 0.037mm, and the maximum field curvature in the sagittal direction is 0.023mm. Fig.11 It can be seen that the field curvature of the optical system provided in Example 2 is relatively small, meeting the requirements for field curvature in the excellent imaging quality standard.

[0219] Fig.12 The distortion curves of the optical system provided in Example 2 at wavelengths of 656nm, 587nm, 546nm, 486nm and 435nm are shown, where the horizontal axis represents the degree of distortion in percentage and the vertical axis represents the field of view in degrees. Fig.12A total of five curves are shown, but the differences between the five curves are very small, resulting in the five curves almost overlapping, so the five curves are not distinguished. ) It can be seen that the distortion of the optical system under this embodiment at a large field angle is less than -62%.

[0220] Example 3

[0221] Fig.13 The schematic diagram of the structure of an optical system provided by this embodiment is shown. In embodiment 3, the optical system includes a first refractive lens 101, a second refractive lens 102, an aperture 30, a super lens 201, a fourth refractive lens 203, a third refractive lens 202, a protective glass 40 and a filter 50 arranged in sequence along the incident light path. Among them, the first refractive lens 101 is an aspherical lens, the other refractive lenses are spherical lenses, and the micro-nano structure 2011 is arranged on the object side of the substrate 2012. The parameters of the optical system are shown in Table 3-1.

[0222] Table 3-1 System parameters of the optical system provided in Example 3

[0223] parameter data Total optical length (TTL) 21.675mm Maximum field of view FOV (2ω) 130° F-number 1.55 Effective focal length (f) 4.34mm Working band Visible light (435nm-656nm)

[0224] As can be seen from Table 3-1, the F number of the optical system in this embodiment is 1.55, and the optical system has a large amount of light intake, ensuring excellent imaging quality. At the same time, the total length of the optical system is only 21.675 mm, which fully meets the requirements of the optical system for miniaturization.

[0225] The surfaces in the optical system are numbered from the object side to the image side, and the parameters of the curvature radius / thickness and material of each lens surface in the optical system are summarized to obtain Table 3-2. The analysis of each surface in Table 3-2 can refer to Example 1 and will not be analyzed again here.

[0226] Table 3-2 Surface parameters of each lens in the optical system provided in Example 3

[0227]

[0228]

[0229] After summarizing the surface parameters of aspheric mirrors, we obtain Table 3-3.

[0230] Table 3-3 Coefficients of the even-order aspheric surface of the optical system provided in Example 3

[0231]

[0232] Figures 14 to 16The MTF field of view curve of the optical system at temperatures of 20°C, -40°C and 105°C is shown, where the horizontal axis is the x-axis field of view, the unit of which is degree; the vertical axis is the MTF value. Figures 14 to 16 The sagittal curve S1 and meridional curve T1 of MTF varying with field of view at 42lp / mm spatial frequency, the sagittal curve S2 and meridional curve T2 of MTF varying with field of view at 83lp / mm spatial frequency, and the sagittal curve S3 and meridional curve T3 of MTF varying with field of view at 167lp / mm spatial frequency are listed respectively.

[0233] Depend on Fig.14 It can be seen that under the condition of 20℃, the MTF value of the optical system in the full field of view at a spatial frequency of 42lp / mm is greater than 0.56, and the imaging quality of the optical system under the condition of a large field of view is extremely high. Under the condition of 20℃, the MTF value of the optical system in the full field of view at a spatial frequency of 83lp / mm is greater than 0.25, which also proves that the optical system has a high imaging quality under the condition of a large field of view. Under the condition of 20℃, the MTF value of the optical system in the 0.9 field of view (58.5°) at a spatial frequency of 167lp / mm is greater than 0.22, which proves that the optical system can process complex images under the condition of a large field of view while also having good imaging quality.

[0234] Depend on Fig.15 It can be seen that under the condition of -40°C and the spatial frequency of the optical system at 42lp / mm, the MTF value of the optical system in the full field of view is greater than 0.51, and the imaging quality of the optical system under the condition of a large field of view is extremely high. Under the condition of -40°C and the spatial frequency of the optical system at 83lp / mm, the MTF value of the optical system in the full field of view is greater than 0.17, which also proves that the optical system has excellent imaging quality under the condition of a large field of view. Under the condition of -40°C and the spatial frequency of the optical system at 167lp / mm, the MTF value of the optical system in the 0.9 field of view (58.5°) is greater than 0.15, and the imaging quality of the optical system is relatively good. Overall Fig.14 and Fig.15 , the imaging quality of the optical system at -40℃ is slightly different from that at 20℃.

[0235] Depend on Fig.16It can be seen that under the condition of 105℃, the optical system has a spatial frequency of 42lp / mm and the MTF value of the optical system in the full field of view is greater than 0.60, and the imaging quality of the optical system under the condition of a large field of view is extremely high. Under the condition of 105℃, the optical system has a spatial frequency of 83lp / mm and the MTF value of the optical system in the full field of view is greater than 0.35. Under the condition of 105℃, the optical system has a spatial frequency of 167lp / mm and the MTF value of the optical system in the 0.9 field of view (58.5°) is greater than 0.31, and the imaging quality of the optical system is good.

[0236] comprehensive Figures 14 to 16 , at -40℃~105℃, the fluctuation of MTF of the optical system is small at the same spatial frequency, indicating that the optical system in this embodiment has good athermal effect and strong temperature adaptability, and high-definition imaging can be achieved under the conditions of -40℃ to 105℃.

[0237] Fig.17 The field curvature of the optical system under this embodiment is shown. Fig.17 The horizontal axis represents the field curvature in millimeters, and the vertical axis represents the field angle in degrees. Fig.17 Middle Curve T 31 is the field curvature of visible light with a wavelength of 656nm in the meridian direction, Fig.17 Middle Curve S 31 The maximum field curvature of the optical system in the meridian direction is 0.018mm, and the maximum field curvature in the sagittal direction is 0.017mm under the visible light with a wavelength of 656nm. Fig.17 Middle Curve T 32 is the field curvature of visible light with a wavelength of 587nm in the meridian direction, curve S 32 The maximum field curvature of the optical system in the meridional direction is 0.017mm, and the maximum field curvature in the sagittal direction is 0.019mm under the visible light with a wavelength of 587nm. Fig.17 Middle Curve T 33 is the field curvature of visible light with a wavelength of 546nm in the meridian direction, curve S 33 The maximum field curvature of the optical system in the meridional direction is 0.017mm, and the maximum field curvature in the sagittal direction is 0.019mm under the visible light with a wavelength of 546nm. Fig.17 Middle Curve T 34 is the field curvature of visible light with a wavelength of 486nm in the meridian direction, curve S 34The maximum field curvature of the optical system in the meridional direction is 0.021mm, and the maximum field curvature in the sagittal direction is 0.023mm under the visible light with a wavelength of 486nm. Fig.17 Middle Curve T 35 is the field curvature of visible light with a wavelength of 435nm in the meridian direction, curve S 35 is the field curvature of visible light with a wavelength of 435nm in the meridional direction. Under visible light with a wavelength of 435nm, the maximum field curvature of the optical system in the meridional direction is 0.018mm, and the maximum field curvature in the sagittal direction is 0.021mm. Fig.11 It can be seen that the field curvature of the optical system provided in Example 3 is relatively small, meeting the requirements for field curvature in the excellent imaging quality standard.

[0238] Fig.18 The distortion curves of the optical system provided in Example 3 at wavelengths of 656nm, 587nm, 546nm, 486nm and 435nm are shown, where the horizontal axis represents the degree of distortion in percentage and the vertical axis represents the field of view in degrees. Fig.18 A total of five curves are shown, but the differences between the five curves are very small, resulting in the five curves almost overlapping, so the five curves are not distinguished. ) It can be seen that the distortion of the optical system under this embodiment at a large field angle is less than -61%.

[0239] After summarizing the lens parameters of the optical system provided in the above embodiments, the following Table 4 is obtained. Table 4 is mainly used to illustrate various conditions satisfied by the optical system provided in the present application, which are all verified and supported by experiments.

[0240] Table 4 Parameters of the optical systems provided in various embodiments

[0241]

[0242]

[0243]

[0244] A second aspect of the present disclosure provides an optical lens (not shown), the optical lens comprising an image sensor and the optical system described in any of the aforementioned technical solutions; wherein the image sensor is arranged on the image plane 60 of the optical system, and the image sensor includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, abbreviated as CMOS, complementary metal oxide semiconductor) and CCD (Charge-coupled Device, abbreviated as CCD, photosensitive coupling component).

[0245] The optical lens provided in the present application has the advantages of small space occupation, good heat elimination effect and low cost. The application scenarios of the optical lens provided in the present application include but are not limited to transportation.

[0246] The above is only a specific implementation of the embodiment of the present disclosure, but the protection scope of the embodiment of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the embodiment of the present disclosure, which should be included in the protection scope of the embodiment of the present disclosure. Therefore, the protection scope of the embodiment of the present disclosure should be based on the protection scope of the claims.

Claims

1. An optical system, characterized in that: The optical system comprises a first lens group (10) and a second lens group (20) which are sequentially arranged along an incident light path; The first lens group (10) comprises a first refractive lens (101) and a second refractive lens (102) which are sequentially arranged along the incident light path; the optical power of the first refractive lens (101) is negative, and the second refractive lens (102) is a biconvex positive lens; The second lens group (20) comprises a metalens (201) and a third refractive lens (202) arranged in sequence along the incident light path; the third refractive lens (202) is a biconvex positive lens; Among the first refractive lens (101), the second refractive lens (102) and the third refractive lens (202), at least the first refractive lens (101) is an aspherical lens.

2. The optical system according to claim 1, characterized in that The second lens group (20) further includes a fourth refractive lens (203); Along the incident light path, the fourth refractive lens (203) is located between the super lens (201) and the third refractive lens (202); and the fourth refractive lens (203) is a biconvex positive lens.

3. The optical system according to claim 1, characterized in that The first refractive lens (101) is an aspherical lens; the second refractive lens (102) and the third refractive lens (202) are spherical lenses.

4. The optical system according to any one of claims 1 to 3, characterized in that: The optical system also satisfies: Wherein, FOV is the maximum field of view of the optical system; F W is the working F number of the optical system; f is the effective focal length of the optical system; TTL is the total optical length of the optical system.

5. The optical system according to claim 2, characterized in that The optical system also satisfies: Wherein, f is the effective focal length of the optical system; n i is the refractive index of the i-th refractive lens in the optical system, f gi is the focal length of the i-th refractive lens in the optical system, i is a positive integer; and t is the ambient temperature.

6. The optical system according to any one of claims 1 to 3, characterized in that: The optical system also satisfies: Wherein, TTL is the total optical length of the optical system; D is the entrance pupil diameter of the optical system; BFL is the optical back focal length of the optical system; and f is the effective focal length of the optical system.

7. The optical system according to any one of claims 1 to 3, characterized in that: The optical system also satisfies: Among them, f B is the focal length of the second lens group (20); FOV is the maximum field angle of the optical system; F W is the working F number of the optical system; f is the effective focal length of the optical system.

8. The optical system according to any one of claims 1 to 3, characterized in that: The optical system also satisfies: Among them, n F is the refractive index of the third refractive lens (202) in the optical system; EXP is the exit pupil diameter of the optical system; R F is the curvature radius of the image side surface of the third refractive lens (202) of the optical system; D F is the aperture of the optical system.

9. The optical system according to any one of claims 1 to 3, characterized in that: The optical system also satisfies: Wherein, TTL is the total optical length of the optical system; F W is the working F number of the optical system; D is the entrance pupil diameter of the optical system; FOV is the maximum field of view angle of the optical system.

10. The optical system according to any one of claims 1 to 3, characterized in that: The optical system also satisfies: Among them, K L1 K is the cone coefficient of the object side surface of the first refractive lens (101) in the optical system along the direction from the object side to the image side along the optical axis; L2 is the cone coefficient of the image side surface of the first refractive lens (101) in the optical system along the direction from the object side to the image side of the optical axis; R L1 is the radius of curvature of the object side surface of the first refractive lens (101) in the optical system in the direction from the object side to the image side along the optical axis; R L2 It is the curvature radius of the image side surface of the first refractive lens (101) in the optical system along the direction from the object side to the image side of the optical axis.

11. The optical system according to claim 2, characterized in that The optical system also satisfies: Among them, CT i is the central thickness of the i-th refractive lens in the optical system, i is a positive integer; TTL is the total optical length of the optical system.

12. The optical system according to any one of claims 1 to 3, characterized in that: The optical power of the metalens (201) is positive, and the phase of the metalens (201) also satisfies: in, is the phase distribution of the superlens (201); and r is the distance from any position on the superlens (201) to the center of the superlens (201).

13. The optical system according to any one of claims 1 to 3, characterized in that: The optical system further comprises a stop (30); The aperture (30) is located between any two adjacent lenses in the optical system; or, the aperture (30) is located on the object side of the first refractive lens (101).

14. The optical system according to claim 13, characterized in that The aperture is located between the second refractive lens (102) and the super lens (201).

15. An optical lens, characterized in that: The lens comprises an image sensor and an optical system according to any one of claims 1 to 14, wherein the image sensor is arranged on an image plane (60) of the optical system.

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