Optical imaging lens and imaging apparatus having the same

Abstract

An optical imaging lens and an imaging device having the same are disclosed. The optical imaging lens includes a plurality of optical lenses arranged from the object side to the image side. Among the optical lenses, the optical lens with the largest focal length is a metasurface lens, and some or all of the other optical lenses are aspherical lenses. The optical imaging lens of this invention, by combining metasurface lenses and aspherical lenses, can at least reduce the overall length of the optical system or increase the imaging area, and can also simplify the manufacturing process and reduce manufacturing costs.

Description

Technical Field

[0001] This utility model relates to the field of optical imaging technology, and in particular to an optical imaging lens and an imaging device having the same. Background Technology

[0002] With the development of technology, the requirements for imaging lenses in daily life have gradually become more stringent, which can be mainly summarized in two directions: first, a more compact module size is needed, and second, a larger imaging area is needed.

[0003] For traditional design methods and lens materials, shortening the total track length (TTL) of the optical system requires increasing the refractive index, but the high dispersion caused by high refractive materials will increase the chromatic aberration of the module; increasing the imaging area will lead to an increase in field curvature, requiring additional correction lenses, which will increase the total length of the optical system; therefore, it cannot meet the requirements of small-sized modules and large imaging areas.

[0004] In view of this, it is necessary to provide an optical imaging lens and an optical lens system having the same, in order to solve the above-mentioned technical problems. Utility Model Content

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art by providing an optical imaging lens and an imaging device having the same, so as to shorten the total length of the optical system and increase the imaging area.

[0006] To achieve one of the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] An optical imaging lens includes a plurality of optical lenses arranged from the object side to the image side, wherein the optical lens with the largest focal length is a metasurface lens, and some or all of the other optical lenses are aspherical lenses.

[0008] In some embodiments, the metasurface lens has an object-side surface facing the object side and an image-side surface facing the image side, and the object-side surface and / or the image-side surface have subwavelength-sized micro / nano structures.

[0009] In some embodiments, the maximum phase difference of the metasurface lens With optical effective radius The ratio between them is ; and / or, the micro / nano structure is a columnar, aperture-shaped, or V-shaped antenna; and / or, the shape of the micro / nano structure is circular or polygonal, the polygon being an n-sided polygon where n is 3-12; and / or, the arrangement of the micro / nano structure is one or more combinations of regular quadrilaterals, regular hexagons, and rings; and / or, the material of the micro / nano structure is titanium dioxide or silicon nitride.

[0010] In some embodiments, the metasurface lens further includes a protective layer, at least partially filling the spaces between the micro / nano structures.

[0011] In some embodiments, the aspherical lens has an object-side surface facing the object side and an image-side surface facing the image side, both of which are aspherical.

[0012] In some embodiments, from the object side to the image side, a plurality of optical lenses sequentially include: a first optical lens, which is an aspherical lens with a focal length of 2.5mm to 3.5mm; a second optical lens, which is a metasurface lens with a focal length of 20mm to 23mm; a third optical lens, which is an aspherical lens or a metasurface lens with a focal length of 10mm to 16mm; and a fourth optical lens, which is an aspherical lens with a focal length of -15mm to 20mm.

[0013] In some embodiments, the first optical lens has a first object-side surface facing the object side and a first image-side surface facing the image side, wherein the region of the first object-side surface near the optical axis is convex and the region of the first image-side surface near the optical axis is concave; and / or, the second optical lens has a second object-side surface facing the object side and a second image-side surface facing the image side, wherein the second object-side surface has a subwavelength micro / nano structure; and / or, the third optical lens has a third object-side surface facing the object side and a third image-side surface facing the image side, wherein the region of the third object-side surface near the optical axis is concave and the region of the third image-side surface near the optical axis is convex; and / or, the fourth optical lens has a fourth object-side surface facing the object side and a fourth image-side surface facing the image side, wherein the region of the fourth object-side surface near the optical axis is convex and the region of the fourth image-side surface near the optical axis is concave.

[0014] In some embodiments, the fourth optical lens includes a first region near the optical axis and a second region located on the side of the first region away from the optical axis, wherein the image-side and object-side of the first region are both convex toward the object side, and the image-side and object-side of the second region are both convex toward the image side.

[0015] In some embodiments, the thickness of the first optical lens is less than the thickness of the third optical lens, and the thickness of the third optical lens is less than the thickness of the fourth optical lens; or, the thickness of the fourth optical lens is greater than the thickness of the first optical lens, and the thickness of the fourth optical lens is greater than the thickness of the third optical lens.

[0016] In some embodiments, the optical imaging lens further includes a filter film disposed on the image-facing surface of the metasurface lens; or, the optical imaging lens further includes a filter located on the image-facing side of the metasurface lens.

[0017] In some implementations, the image height Imgh of the optical imaging lens is 2.2mm-2.50mm; and / or, the total length TTL of the optical system is 2.27-2.57mm; and / or, the aperture coefficient Fno is 2.4-2.8; and / or, the maximum field of view FOV is 88-93; and / or, the relative illumination is >21%; and / or, the optical modulation transfer function MTF is >0.5; and / or, the focal length f of the metasurface lens is 20mm-23mm; and / or, the total effective focal length f is 1.8mm-2.3mm.

[0018] An imaging device comprising any of the optical imaging lenses described above.

[0019] The beneficial effects of this utility model are: the optical imaging lens of this utility model, by combining metasurface lens and aspherical lens, can at least reduce the total length of the optical system or increase the imaging area, and can simplify the manufacturing process and reduce manufacturing costs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an optical imaging lens in one embodiment of the present invention.

[0021] Figure 2 for Figure 1 The MTF curve of the optical imaging lens in the image.

[0022] Figure 3 for Figure 1 A diagram of light spots from an optical imaging lens.

[0023] Figure 4 for Figure 1 Field curvature distortion diagram of the optical imaging lens in the image.

[0024] Figure 5 for Figure 1 The relative illumination of the optical imaging lens in the image.

[0025] Figure 6 for Figure 1 The transverse chromatic aberration diagram of the optical imaging lens in the image.

[0026] Figure 7 This is a schematic diagram of the structure of an optical imaging lens in another embodiment of the present invention.

[0027] Figure 8 for Figure 7 The MTF curve of the optical imaging lens in the image.

[0028] Figure 9 for Figure 7 A diagram of light spots from an optical imaging lens.

[0029] Figure 10 for Figure 7 Field curvature distortion diagram of the optical imaging lens in the image.

[0030] Figure 11 for Figure 7 The relative illumination of the optical imaging lens in the image.

[0031] Figure 12 for Figure 7 The transverse chromatic aberration diagram of the optical imaging lens in the image.

[0032] Figure 13 This is a cross-sectional schematic diagram of the metasurface structure in this utility model.

[0033] Among them, 100-optical imaging lens, 1-first optical lens, 2-second optical lens, 21-substrate, 22-micro-nano structure, 23-protective layer, 3-third optical lens, 4-fourth optical lens, S2-first object side surface, S3-first image side surface, S4-second object side surface, S5-second image side surface, S6-third object side surface, S7-third image side surface, S8-fourth object side surface, S9-fourth image side surface, S10-image plane. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the protection scope of the present invention.

[0035] In the various figures of this utility model, for ease of illustration, some dimensions of the structure or part may be exaggerated relative to other structures or parts. Therefore, they are only used to illustrate the basic structure of the subject matter of this utility model.

[0036] The inventors discovered that metasurfaces, structural materials composed of subwavelength structural units, possess the significant advantage of flexible phase control. By precisely designing the structure and arrangement of metasurface units, arbitrary control of the phase, amplitude, and polarization of light waves can be achieved at the subwavelength scale, thus providing unprecedented freedom for optical system design. Compared to traditional optical elements, metasurfaces can achieve complex optical functions with extremely thin thicknesses (typically in the nanometer to micrometer range); and due to their planar structure, they are easy to fabricate and inexpensive. Based on their phase-controllable characteristics, a single metasurface can equivalently replace multiple traditional lenses, providing a new solution for the compactness and large image size of front-facing camera modules.

[0037] Please see Figure 1 and Figure 7The image shown is an optical imaging lens 100 according to a preferred embodiment of the present invention. The optical imaging lens 100 includes a plurality of optical lenses arranged from the object side to the image side, wherein the optical lens with the largest focal length is a metasurface lens (or superlens), and some or all of the other optical lenses are aspherical lenses.

[0038] Compared to traditional optical imaging lenses formed by refractive lenses, this invention uses metasurface lenses to replace part of the refractive lenses, forming a combination of aspherical lenses and metasurface lenses. By utilizing the advantages of metasurfaces, the overall length of the optical system can be shortened and the imaging quality can be improved.

[0039] Specifically, designing the optical lens with the longest focal length as a metasurface lens, and designing the optical lens with the most complex structure that mainly undertakes image quality control functions as a metasurface lens, allows it to primarily undertake most of the image quality optimization functions in the optical path. This avoids excessively large phase gradients on the metasurface, which would lead to insufficient sampling of the nanopillar arrangement at the metasurface edge, resulting in a decrease in metasurface efficiency. Furthermore, the introduction of metasurface lenses can reduce the number of lenses used, making the optical system structure more compact.

[0040] Metasurface lenses have an object-side surface facing the object side and an image-side surface facing the image side. The object-side surface and / or the image-side surface have micro / nano structures 22 with subwavelength dimensions. That is, at least one of the object-side surface and the image-side surface is designed as a metasurface. Both can achieve the effect of shortening the total length of the optical system and improving the imaging quality.

[0041] In one specific embodiment, the micro / nano structure 22 is disposed on the side of the object to perform pre-dispersion compensation for the incident light and to compensate for the chromatic aberration of the light passing through the metasurface lens.

[0042] In another specific embodiment, the micro / nano structure 22 is disposed on the image side, which determines the propagation direction of the emitted light, and the phase modulation is more direct, which is beneficial to the correction of aberrations.

[0043] In one embodiment, the maximum phase difference of the metasurface lens With optical effective radius The ratio between them is By controlling the ratio between the maximum phase difference of the superlens and its effective optical radius, the 2π phase period undertaken by the superlens per unit length matches the phase matching effect of the micro / nano structure 22 on its target phase, thus making fuller use of the optical performance of the superlens.

[0044] Please refer to Figure 13 As shown, the metasurface lens includes a substrate 21 and a micro / nano structure layer located on at least one side of the substrate 21 (object side and / or image side). The micro / nano structure layer, namely the layer composed of micro / nano structures 22, is a key functional layer for controlling imaging.

[0045] The substrate 21 and the micro / nano structure layer can be integrated or separate, both of which can achieve the effect of a metasurface.

[0046] The substrate 21 may be made of materials including, but not limited to, glass substrates and silicon substrates. These materials have good light transmittance and high refractive index to improve phase modulation efficiency. Furthermore, these materials have high surface stability to prevent damage to the micro / nano structure layer during fabrication or use.

[0047] In one specific embodiment, BF33 glass is selected as the substrate 21 of the metasurface lens. BF33 glass is a high borosilicate glass, also known as Schott glass. BF33 glass has excellent thermal stability and minimal impact on the micro / nano structure 22; it has good light transmittance, exhibiting good light transmittance in the ultraviolet to visible light bands; it has high surface flatness and is easy to process.

[0048] The micro / nano structure layer includes several subwavelength micro / nano structures 22. The material, shape, and arrangement of the micro / nano structures 22 are related to the imaging requirements.

[0049] In some embodiments, the micro / nano structure 22 is made of materials such as titanium dioxide or silicon nitride, which have good light transmittance, high stability, and are easy to process.

[0050] In some implementations, the micro / nano structure 22 is a columnar, aperture-shaped, or V-shaped antenna. The fabrication process is relatively mature, and the structure has high stability and yield, making it suitable for mass production.

[0051] In some implementations, the micro / nano structure 22 is circular or polygonal in shape. Circular structures are more commonly used due to their lack of influence on polarization and ease of fabrication. Polygons are n-sided, where n is 3-12, such as squares.

[0052] In some implementations, the micro-nano structures 22 are arranged in a combination of one or more of the following: squares, hexagons, and rings.

[0053] Specifically, the material, shape, and arrangement of the micro / nano structure 22 can be arbitrarily combined from the above description. In this invention, the micro / nano structure 22 is a circular nanopillar, or a square or circular pore.

[0054] The metasurface lens also includes a protective layer 23, at least partially filled between the micro / nano structures 22 to protect the micro / nano structures 22.

[0055] In a preferred embodiment, the protective layer 23 extends beyond the micro / nano structure 22 in the direction away from the substrate 21 to completely enclose the micro / nano structure 22.

[0056] The protective layer 23 can be selected from, but is not limited to, air, adhesive, SiO2, Si3N4, etc.

[0057] All lenses except the optical lens with the longest focal length are aspherical lenses. Alternatively, in addition to the optical lens with the longest focal length, one part of the lenses is an aspherical lens, while the other part is not limited to any particular type, such as spherical lenses or metasurface lenses.

[0058] Aspherical lenses have an object-side surface facing the object and an image-side surface facing the image. To achieve astigmatism and focusing, the object-side and image-side surfaces are usually convex or concave.

[0059] Setting a convex surface as an aspherical surface can correct spherical aberration and other aberrations in a positive optical system; setting a concave surface as an aspherical surface is used for correction in a negative optical system. Therefore, in a preferred embodiment, both the object-side surface and the image-side surface are aspherical, improving image quality.

[0060] Based on the above arbitrary design, in some embodiments, the optical imaging lens 100 includes four optical lenses, which are arranged from the object side to the image side as follows: first optical lens 1, second optical lens 2, third optical lens 3 and fourth optical lens 4.

[0061] The first optical lens 1 is located on the incident side of the light, furthest from the image side. In other words, the optical path structure is too far forward, making it difficult to adjust the aberrations of subsequent optical paths. The first optical lens 1 has a small focal length and mainly serves the function of collecting light in the optical path, with little effect on the control of light or the control of image quality.

[0062] In one embodiment, the focal length of the first optical lens 1 is 2.5mm-3.5mm, preferably 3mm±0.2mm. The first optical lens 1 is an aspherical lens.

[0063] In one embodiment, the first optical lens 1 has a first object-side surface S2 facing the object side and a first image-side surface S3 facing the image side. The area of ​​the first object-side surface S2 near the optical axis is convex, and the area of ​​the first image-side surface S3 near the optical axis is concave. Both the first object-side surface S2 and the first image-side surface S3 are aspherical.

[0064] The second optical lens 2 has a large focal length and the smallest optical power. In the optical path, it mainly functions to control image quality and also undertakes a small part of the light focusing function. At least one surface of the second optical lens 2 is a metasurface with micro / nano structures 22 on the subwavelength scale.

[0065] By designing metasurfaces, the phase, amplitude, and polarization of light waves can be arbitrarily controlled, thus providing unprecedented freedom for optical system design, optimizing image quality, compensating for chromatic aberration in traditional lenses, and improving imaging quality.

[0066] In one embodiment, the focal length of the metasurface lens is 20mm-23mm, for example, 20.5mm±0.2mm, 21mm±0.2mm, 21.5mm±0.2mm, 22mm±0.2mm, or 22.5mm±0.2mm.

[0067] The second optical lens 2 has a second object side surface S4 facing the object side and a second image side surface S5 facing the image side. The second object side surface S4 has a subwavelength micro / nano structure 22.

[0068] The focal length of the third optical lens 3 is 10mm to 16mm, for example, 10.5mm, 11mm, 12mm, 13mm, 14mm, or 15mm. The main function of the third optical lens 3 is to focus light, and it also plays a minor role in adjusting image quality. The third optical lens 3 undertakes a certain image quality adjustment function, and a metasurface lens can also be used to improve image quality to some extent.

[0069] In one embodiment, the third optical lens 3 is an aspherical lens. The third optical lens 3 has a third object-side surface S6 facing the object side and a third image-side surface S7 facing the image side. The area of ​​the third object-side surface S6 near the optical axis is concave, and the area of ​​the third image-side surface S7 near the optical axis is convex. Both the third object-side surface S6 and the third image-side surface S7 are aspherical.

[0070] In one embodiment, the third optical lens 3 is a metasurface lens. The third object-side surface S6 and / or the third image-side surface S7 are metasurfaces formed by micro / nano structures 22.

[0071] The fourth optical lens, located closest to the image side, performs most of the focusing function in the optical path. In this embodiment, the focal length is -15mm to 20mm.

[0072] Further research by the inventors revealed that the fourth optical lens 4 performs too much focusing work. If an equivalent metasurface is added as a replacement, the phase gradient of the metasurface becomes too large, leading to insufficient sampling of the nanopillar arrangement at the metasurface edge and a decrease in the metasurface's efficiency. Therefore, the fourth optical lens 4 is an aspherical lens.

[0073] The fourth optical lens 4 has a fourth object-side surface S8 facing the object side and a fourth image-side surface S9 facing the image side. The area of ​​the fourth object-side surface S8 near the optical axis is convex, and the area of ​​the fourth image-side surface S9 near the optical axis is concave. Both the fourth object-side surface S8 and the fourth image-side surface S9 are aspherical.

[0074] Additionally, the fourth optical lens 4 includes a first region close to the optical axis and a second region located on the side of the first region away from the optical axis. The image-side and object-side of the first region are both convex towards the object side, and the image-side and object-side of the second region are both convex towards the image side, which is beneficial for increasing the image height.

[0075] Based on the above, the thickness of the first optical lens 1 is less than the thickness of the third optical lens 3, and the thickness of the third optical lens 3 is less than the thickness of the fourth optical lens 4. Alternatively, the thickness of the fourth optical lens 4 is greater than the thickness of the first optical lens 1, and the thickness of the fourth optical lens 4 is greater than the thickness of the third optical lens 3. This combination of thicknesses for multiple optical lenses facilitates the fabrication of aspherical surfaces on each lens, optimizes the optical path, and improves image quality.

[0076] This invention employs a metasurface lens in combination with multiple aspherical lenses, which simplifies lens design and manufacturing processes and improves image quality. Furthermore, the second optical lens 2, which has the most complex structure and primarily functions to control image quality, is designed as a metasurface lens, resulting in optimal imaging performance.

[0077] In addition, based on the above-mentioned structure, the optical imaging lens 100 also includes a filter structure. The filter structure only allows light signals of a specific wavelength band to pass through, while blocking light signals of other wavelength bands. By setting the filter structure, light of the working wavelength band can be effectively captured while reducing stray light interference from other wavelength bands, enhancing the imaging device's sensitivity to light and its ability to capture light, and ensuring image quality.

[0078] In some implementations, the filtering structure is a filter film. The filter film only allows light signals in the operating wavelength band to pass through, while blocking light signals outside the operating wavelength band. This reduces stray light interference from wavelengths outside the operating wavelength band, enhances the imaging device's sensitivity and capturing ability to light, and ensures image quality. The filter film can be integrated onto any optical lens without increasing the number of optical lenses.

[0079] In one embodiment, the filter film is located on the image-facing surface of the metasurface lens, that is, on the light-emitting surface of the metasurface lens. By placing the filter film on one surface of the metasurface lens, a filtering effect can be achieved without increasing the number of devices, simplifying the structure, facilitating miniaturization, and simplifying production. Furthermore, the image-facing surface of the metasurface lens is planar, which facilitates the fabrication or bonding of the filter film.

[0080] In some embodiments, the filtering structure is a filter, which is located on the side of the metasurface lens facing the image side, for example, between the second optical lens 2 and the third optical lens 3, or between the third optical lens 3 and the fourth optical lens 4, and can also achieve the same filtering effect as a filter film.

[0081] Based on the above design, the optical imaging lens of this utility model combines small size with excellent imaging capabilities. Specifically, the optical imaging lens satisfies a combination of at least one or more of the following parameters: image height (Imgh) of 2.2mm-2.50mm, resulting in a large imaging area; total optical system length (TTL) of 2.27-2.57mm, meeting the small size requirement; aperture coefficient (Fno) of 2.4-2.8, providing moderate light intake and exposure time; maximum field of view (FOV) of 88°-93°, offering a wide field of view; relative illumination >21%, resulting in a high ratio of brightness between the edge and center of the field of view; optical modulation transfer function (MTF) >0.5, ensuring high image quality; and a metasurface lens focal length (f) of 20mm-23mm; and / or a total effective focal length (f) of 1.8mm-2.3mm. The optical imaging lens as a whole forms high-quality images, suitable for various imaging scenarios and devices.

[0082] The optical imaging lens 100 of this utility model will be described below in conjunction with its design and manufacturing process.

[0083] Step 1: Optimize the optical path structure using optical design software.

[0084] S11 determines the initial parameters of the optical system based on the requirements of the imaging lens. These requirements include operating wavelength, field of view, focal length, and resolution. The initial parameters include, but are not limited to, the number, thickness, and material of metasurfaces.

[0085] S12 determines the location of the metasurface.

[0086] Based on the above explanation, the metasurface primarily serves to optimize image quality in the optical path, minimizing optical power and avoiding excessive phase gradients. Excessive phase gradients on the metasurface would lead to insufficient arrangement of micro / nano structures 22 (such as nanopillars) at its edges, resulting in decreased metasurface efficiency. In this invention, the refractive lens with the largest focal length is designed as a metasurface lens.

[0087] S13 Ray Tracing and Wavefront Optimization.

[0088] A planar optical system model is built in optical simulation software (such as Zemax or Code V), and a metasurface (or phase surface) is used to replace the traditional refractive lens to simulate the modulation effect of the metasurface on light waves.

[0089] By utilizing the ray tracing function of optical software, optical path parameters are analyzed and optimized. Optimization targets include: beam focusing for module imaging; aberration correction to eliminate spherical aberration, coma, etc., and improve image quality; and field of view expansion to ensure the clarity of eye tracking at large angles.

[0090] By optimizing the software algorithm, the parameters of the metasurface lens are adjusted to ensure that the system meets the requirements of optical modulation transfer function (MTF) and spot diagram.

[0091] Step 2: Metasurface phase design and nanostructure realization.

[0092] S21 extracts the target phase distribution from the optimized optical system, where the phase is defined by the surface shape formula.

[0093] S22 nanostructure unit (Meta-atom) design.

[0094] S221 selects a high refractive index material as the metasurface substrate 21 to improve phase modulation efficiency. The metasurface substrate 21 includes, but is not limited to, silicon nitride substrates and titanium dioxide substrates.

[0095] The S222 design incorporates subwavelength structural units to provide the required phase delay at the operating wavelength. These subwavelength structural units include one or more combinations of nanopillars, nanopores, and V-shaped antennas. Operating wavelengths include visible light, infrared, and ultraviolet light. The phase delay ranges from 0 to 2π.

[0096] S223 employs finite-difference time-domain (FDTD) or rigorous coupled-wave analysis (RCWA) to simulate and optimize the scattering characteristics of individual nanostructures, ensuring phase modulation accuracy.

[0097] S23 metasurface array arrangement. Based on the phase distribution, nanostructures of different sizes / shapes are arranged in a gradient manner to form a complete metasurface lens. Structural parameters are optimized in conjunction with manufacturing process constraints such as photolithography precision and etching depth to ensure practical fabrication feasibility.

[0098] S24 System Integration and Testing. This involves integrating metasurface lenses with components such as CMOS sensors and filters to construct a complete imaging module. Experimental tests (such as MTF measurement and accuracy evaluation) are used to verify whether the system's performance meets design requirements.

[0099] Step 3: Preparation of metasurfaces.

[0100] S31 substrate 21 pretreatment. For material selection, titanium dioxide / SiO2 is commonly used in the visible light band, while amorphous silicon or silicon carbide wafers are used in the near-infrared band. Surface cleaning is also required, including ultrasonic cleaning with alkaline solutions to remove oil stains and ICP ion bombardment to remove volatile residues.

[0101] S32 functional layer deposition. The main processes include magnetron sputtering, electron beam evaporation, and atomic layer deposition to form the functional layer for fabricating micro / nano structures 22.

[0102] S33 patterning transfer. The original mold is created by electron beam lithography, followed by development and fixing, imprinting, curing, structure transfer to the dielectric layer, metal mask deposition, and etching.

[0103] S34 structure etching and molding. Pattern fidelity control is performed to reduce sidewall angle deviation.

[0104] S35 post-processing and encapsulation. Residual adhesive is removed, and a surface coating is applied to enhance performance.

[0105] A basic metasurface lens, such as Figure 13 As shown, the light source is incident from the substrate 21. The type of light source includes, but is not limited to, LED, EEL, VCSEL, fiber laser, natural light, etc. In this embodiment, an LED light source is selected.

[0106] Specifically, in the optical design section, the basic parameters are first defined. This invention takes the visible light band as the working band as an example; it is adapted to conventional use scenarios, with a field of view (FOV) of 90°; the focal length is as small as possible to meet the needs of miniaturized modules; the imaging resolution requires an MTF greater than 0.5 at 110 Hz and an image height (maximum imaging height, 1 mgH) greater than 2.1 mm.

[0107] A traditional lens module was selected as the basis for optimization, with the following parameters: total optical system length 2.57mm, image height 2.07mm, relative illumination >21%, MTF (@110 lp / mm) greater than 0.5 at a field of view of 0.8F, aperture number (F-number, Fno) 2.4, maximum field of view (FOV) 90°, and effective focal length 2mm.

[0108] This utility model provides two specific embodiments, corresponding to two optimization directions: size reduction and image plane enlargement, respectively.

[0109] Table 1

[0110]

[0111] S4 is the metasurface nanostructure layer. S2-S3 and S6-S9 are Q-type aspherical surfaces; S10 is the image plane.

[0112] Example 1: While reducing the size, the image plane is increased.

[0113] Please refer to Figure 1 As shown, the optical imaging lens 100 comprises three aspherical lenses and one metasurface lens. Detailed system parameters are shown in Table 1.

[0114] Table 2 Extended parameters of aspherical surfaces

[0115]

[0116] Table 3 Phase factors of the equivalent surface type of the metasurface

[0117]

[0118] Compared to traditional lenses, Embodiment 1 only replaces the second optical lens 2 with a metasurface lens, which has the following advantages: the total length (TTL) of the optical system is significantly reduced, from 2.57mm to 2.27mm. The image height is also increased from 2.07mm to 2.2mm.

[0119] Figure 2-6 Some basic optical properties of Embodiment 1 are illustrated. As can be seen from the accompanying drawings, in this embodiment, a metasurface lens is used to constrain... By controlling the ratio between the maximum phase difference of the metasurface lens and the optical effective radius, the 2π phase period undertaken by the metasurface lens per unit length is made to match the target phase of the micro / nano structure 22, thus giving fuller play to the optical performance of the metasurface lens.

[0120] Example 2

[0121] Please refer to Figure 7 As shown, the optical imaging lens 100 comprises three aspherical lenses and one metasurface lens. Detailed system parameters are shown in Table 4.

[0122] In this embodiment, the filter film is set on the S5 surface, which is the side of the metasurface lens facing the image, that is, the outgoing light surface of the metasurface lens.

[0123] Table 4

[0124]

[0125] Table 5 Extended parameters of aspherical surfaces

[0126]

[0127] Table 6 Phase factors of the equivalent surface type of the metasurface

[0128]

[0129] In Embodiment 2, the first optical lens 1 is an aspherical lens with a focal length of 2.9 mm, the second optical lens 2 is a metasurface lens with a focal length of 20.5 mm, the third optical lens 3 is an aspherical lens with a focal length of 11.9 mm, and the fourth optical lens 4 is an aspherical lens with a focal length of -10.9 mm.

[0130] The total length (TTL) of the optical system is 2.57 mm, the image height (Imgh) is 2.3 mm, the aperture (Fno) is 2.8, the maximum field of view (FOV) is 92.8°, the focal length (f) of the metasurface lens is 20.5 mm, and the total effective focal length (f) of the optical imaging lens 100 is 2.15 mm.

[0131] Compared to traditional lenses, Embodiment 2 only replaces the second optical lens 2 with a metasurface lens, which has the following advantages: the image height is increased from 2.07mm to 2.3mm without changing the total length TTL of the optical system.

[0132] Figure 8-12 Some basic optical properties of Example 2 are shown, including MTF curves, spot pattern diagrams, field curvature distortion diagrams, relative illumination, and transverse chromatic aberration diagrams. In Example 2, a phase plane is used as an equivalent replacement for the metasurface to constrain... By controlling the ratio between the maximum phase difference of the superlens and the effective optical radius, the 2π phase period undertaken by the superlens per unit length conforms to the matching effect of the micro / nano structure 22 on its target phase, thus making fuller use of the optical performance of the superlens.

[0133] The main optimization direction of Example 1 is to reduce the overall length of the optical system while increasing the image height. The main optimization direction of Example 2 is to increase the image height. It can be seen that by adopting the concept of a hybrid design of "aspherical lens-metasurface lens", the overall length of the optical system can be significantly reduced, and the image plane can be increased, providing a reliable design solution for compact and high-performance lenses.

[0134] It should be noted that Embodiments 1 and 2 are merely illustrative of the present invention, and the solution is not limited thereto. Although the embodiments only illustrate one metasurface, the number of metasurfaces is not limited to one and can be more. For example, the third optical lens 3 can also be replaced by a metasurface lens.

[0135] The main operation method of the embodiment is to replace the traditional lens with a brand-new metasurface lens and then optimize it. In fact, it is not limited to replacement. A metasurface can be directly added as the above-mentioned metalens on the basis of the original traditional lens module. That is, the metasurface lens can also be formed by forming a micro-nano structure 22 on the surface of the original second optical lens 2. This method cannot reduce the overall length of the optical system, but it can achieve the effect of increasing the image area.

[0136] The operating band of this embodiment is visible light, which can be extended to the ultraviolet and infrared bands.

[0137] This utility model also provides an imaging device, including any of the above-mentioned optical imaging lenses 100, which can enable the imaging device to have a smaller size while meeting imaging requirements.

[0138] The imaging device of this invention includes, but is not limited to, devices such as mobile phones, cameras, video cameras, and telescopes. Furthermore, the optical imaging lens 100 can be used as any lens of the imaging device; for example, it can be used as the front camera lens of a mobile phone, or as the rear camera lens of a mobile phone.

[0139] In summary, the optical imaging lens 100 of this invention replaces or modifies some of the refractive optical lenses in traditional imaging lenses with metasurface lenses. By combining metasurface lenses with aspherical lenses, the size and thickness of the module can be significantly reduced. Furthermore, the image plane height can be increased while maintaining or reducing the system length, thus covering a higher number of pixels. Metasurface lenses are manufactured using semiconductor processes (such as electron beam lithography and nanoimprint lithography), making them suitable for mass production, simplifying the manufacturing process, and reducing manufacturing costs. The overall structural design of the optical imaging lens 100 provides a highly integrated, low-cost solution for next-generation smart devices.

[0140] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0141] The detailed descriptions listed above are merely specific descriptions of feasible implementations of this utility model, and are not intended to limit the scope of protection of this utility model. All equivalent implementations or modifications made without departing from the spirit of this utility model should be included within the scope of protection of this utility model.

Claims

1. An optical imaging lens, comprising a plurality of optical lenses arranged from the object side to the image side, characterized in that, Among a number of optical lenses, the optical lens with the longest focal length is a metasurface lens, and some or all of the other optical lenses are aspherical lenses. From the object side to the image side, the optical lenses sequentially include: The first optical lens is an aspherical lens with a focal length of 2.5mm to 3.5mm; The second optical lens is a metasurface lens with a focal length of 20mm-23mm; The third optical lens is an aspherical lens or a metasurface lens with a focal length of 10mm to 16mm. The fourth optical lens is an aspherical lens with a focal length of -15mm to 20mm. 2.The optical imaging lens according to claim 1, wherein: The metasurface lens has an object-side surface facing the object side and an image-side surface facing the image side, and the object-side surface and / or the image-side surface have subwavelength-sized micro / nano structures. ​ 3. The optical imaging lens according to claim 2, characterized in that: a maximum phase difference of the metasurface lens a ratio between an optical effective radius and a radius of the metasurface lens is ; And / or, the micro / nano structure is a columnar, aperture-shaped, or V-shaped antenna; And / or, the shape of the micro / nano structure is circular or polygonal, wherein the polygon is an n-sided polygon, and n is 3-12; And / or, the arrangement of the micro-nano structures is one or more combinations of squares, hexagons, and rings; And / or, the material of the micro / nano structure is titanium dioxide or silicon nitride. 4.The optical imaging lens according to claim 2, wherein: 0.5 < d2 / d1 < 1.

5. The metasurface lens also includes a protective layer, at least a portion of which fills the spaces between the micro / nano structures.

5. The optical imaging lens according to claim 1, characterized in that: The aspherical lens has an object-side surface facing the object and an image-side surface facing the image, both of which are aspherical.

6. The optical imaging lens according to claim 1, characterized in that: The first optical lens has a first object-side surface facing the object side and a first image-side surface facing the image side. The area of ​​the first object-side surface near the optical axis is convex, and the area of ​​the first image-side surface near the optical axis is concave. And / or, the second optical lens has a second object-side surface facing the object side and a second image-side surface facing the image side, the second object-side surface having a subwavelength micro / nano structure; And / or, the third optical lens has a third object-side surface facing the object side and a third image-side surface facing the image side, the area of ​​the third object-side surface near the optical axis is concave, and the area of ​​the third image-side surface near the optical axis is convex. And / or, the fourth optical lens has a fourth object-side surface facing the object side and a fourth image-side surface facing the image side, the area of ​​the fourth object-side surface near the optical axis being convex and the area of ​​the fourth image-side surface near the optical axis being concave. 7.The optical imaging lens according to claim 6, wherein: The fourth optical lens includes a first region close to the optical axis and a second region located on the side of the first region away from the optical axis. The image side and object side of the first region are both convex to the object side, and the image side and object side of the second region are both convex to the image side. 8.The optical imaging lens according to claim 6, wherein: The thickness of the first optical lens is less than the thickness of the third optical lens, and the thickness of the third optical lens is less than the thickness of the fourth optical lens; ​ Alternatively, the thickness of the fourth optical lens is greater than the thickness of the first optical lens, and the thickness of the fourth optical lens is greater than the thickness of the third optical lens.

9. The optical imaging lens according to any one of claims 1-8, characterized in that: The optical imaging lens also includes a filter film, which is disposed on the image-facing surface of the metasurface lens; Alternatively, the optical imaging lens may further include a filter located on the side of the metasurface lens facing the image side. 10.The optical imaging lens according to claim 1, wherein: The image height (Imgh) of the optical imaging lens is 2.2mm-2.50mm; and / or, the total length (TTL) of the optical system is 2.27-2.57mm; and / or, the aperture coefficient (Fno) is 2.4-2.8; and / or, the maximum field of view (FOV) is 88-93; and / or, the relative illumination is >21%; and / or, the optical modulation transfer function (MTF) is >0.5; and / or, the focal length (f) of the metasurface lens is 20mm-23mm; and / or, the total effective focal length (f) is 1.8mm-2.3mm.

11. An image forming apparatus characterized by comprising: Includes the optical imaging lens as described in any one of claims 1 to 10.

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