Camera modules and electronic devices

Abstract

This application discloses a camera module including a lens, an image sensor, and a metalens. The image sensor is located on the image side of the lens, and the metalens is located between the lens and the image sensor. The metalens includes a substrate and multiple pillars, which are fixed to the side of the substrate facing the image sensor. Each pillar has a rotationally symmetric structure with a rotation angle of 90°. The metalens is used to split the light beam and project it onto the image sensor, enabling the camera module to achieve multispectral imaging and a small size. This application also discloses an electronic device using the above-described camera module.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and more particularly to a camera module and electronic device. Background Technology

[0002] Spectral cameras can record both the two-dimensional spatial information and the spectral information of an object. Spectral information reveals the field intensity distribution of different light wavelengths, enabling functions such as material identification and color enhancement. For example, in current augmented reality (AR) fields, such as the Cyberverse system, spectral cameras provide more refined spectral information, thereby improving the system's lighting rendering capabilities. Simultaneously, they can also provide algorithmic input for material analysis, facilitating the construction of more realistic augmented reality spaces and enhancing the user experience. However, current spectral cameras are typically bulky, making them difficult to apply to miniaturized electronic devices. Summary of the Invention

[0003] This application provides a camera module and an electronic device. The camera module is capable of capturing multispectral images and is small in size.

[0004] In a first aspect, a camera module is provided, including a lens, an image sensor, and a metalens. The image sensor is located on the image side of the lens, and the metalens is located between the lens and the image sensor. The metalens includes a substrate and multiple pillars, which are fixed to the side of the substrate facing the image sensor. Each pillar has a rotationally symmetric structure with a rotation angle of 90°. The metalens has multiple beam-splitting units arranged in an array. Each beam-splitting unit is used to split the light beam into multiple sub-beams according to the wavelength band and project them onto the image sensor.

[0005] In this application, the camera module achieves light field imaging and multispectral imaging by setting the beam-splitting function of the meta-lens unit. Therefore, only one lens is needed to collect the reflected light from the subject, and there is no need to use components such as prisms as beam-splitting devices. This results in high image overlap accuracy and high imaging quality of the captured multispectral images. At the same time, the optical system of the camera module has fewer components and a simpler composition, making the camera module low in cost and small in size.

[0006] The beam splitting unit includes a first beam splitting unit, which is used to split the light beam into multiple sub-beams according to the wavelength along a first direction and project them onto the image sensor. In the first beam splitting unit, multiple columns are arranged in a row along the first direction and in a column along a second direction, which is perpendicular to the first direction. At least some of the columns in the same row have different outer diameters, while multiple columns in the same column have the same outer diameter.

[0007] In this implementation, the metalens's cylindrical body adopts a rotationally symmetric structure with a rotation angle of 90°. Therefore, the optical system of the camera module using this metalens is a polarization-independent system. Since the camera module's optical system is polarization-independent, it does not require components such as linear polarizers or quarter-wave plates. The optical system has a simple composition and compact component arrangement, resulting in a small camera module size that can be well applied to small electronic devices.

[0008] Furthermore, since the height of the microstructures (i.e., pillars) of the metasurface structure is on the order of single-digit micrometers, the overall volume of the meta lens is very small, which reduces the structural design difficulty of the camera module and makes the camera module smaller, which is beneficial for the application of the camera module in miniaturized electronic devices.

[0009] In some possible implementations, in the first beam splitting unit, the column extends along a third direction, which is perpendicular to the first and second directions, and the cross-sectional shape of the column is circular, square, or octagonal.

[0010] In some possible implementations, multiple pillars are arranged at equal intervals in a first direction with a spacing in the range of 150nm to 300nm, and multiple pillars are arranged at equal intervals in a second direction with a spacing in the range of 150nm to 300nm.

[0011] In some possible implementations, the height of the column in the third direction is in the range of 500nm to 2000nm, and the third direction is perpendicular to the first and second directions.

[0012] Specifically, by designing the outer diameter of multiple pillars located in the same row of the first beam splitting unit, the first beam splitting unit can divide the beam into multiple sub-beams according to the wavelength, and the multiple sub-beams are projected along the first direction onto different positions of the photosensitive units of the corresponding image sensor.

[0013] In some possible implementations, the outer diameter of the column is in the range of 40 nm to 200 nm.

[0014] In some possible implementations, the pillar is made of a semiconductor material. The semiconductor material could be gallium nitride, titanium dioxide, or silicon nitride, among others.

[0015] In some possible implementations, the outer diameters of multiple cylinders in the same row in the first beam splitting unit are distributed in an oblique trapezoidal aperiodic pattern.

[0016] In some possible implementations, the substrate is made of silicon dioxide or sapphire.

[0017] In some possible implementations, the height of the substrate in the third direction ranges from 100μm to 500μm, and the third direction is perpendicular to the first and second directions. Since the height of the metalens is very small, the main thickness of the metalens is formed by the substrate. When the thickness of the substrate is less than 500μm, the thickness of the metalens is very small, which is beneficial for the miniaturization of the camera module.

[0018] In some possible implementations, the multiple beam-splitting units further include a second beam-splitting unit, which is used to split the light beam into multiple sub-beams along a second direction according to wavelength and project them onto the image sensor. In the second beam-splitting unit, multiple columns are arranged in a row along a first direction and in a column along a second direction. Each column is rotationally symmetric with a rotation angle of 90°. Columns in the same row have the same outer diameter, while at least some columns in the same column have different outer diameters. The design of the second beam-splitting unit can be referenced from that of the first beam-splitting unit.

[0019] In some possible implementations, the metalens also includes a filter film, which is fixed to the side of the substrate facing away from the multiple pillars. The filter film is used to filter infrared light. In this implementation, since the metalens integrates filtering function while achieving beam splitting and focusing functions, the camera module does not need to have a filter, simplifying the component composition of the camera module and making the thickness of the camera module smaller, which is beneficial for the miniaturization of the camera module and the electronic device using the camera module.

[0020] In some possible implementations, the camera module also includes a filter located between the lens and the metalens, used to filter infrared light. For example, the filter may include a substrate and a filter film fixed to the substrate. The substrate may be made of sapphire, the main component of which is aluminum oxide.

[0021] The aforementioned filter film may include an infrared cut-off film. For example, the infrared cut-off film is used to filter infrared light with wavelengths greater than 950 nm. In some implementations, the filter film may also include an ultraviolet cut-off film, so that the filter can also filter ultraviolet light.

[0022] In some possible implementations, the image sensor includes multiple photosensitive units, which are configured one-to-one with multiple beam-splitting units, and the sub-beams formed by the beam-splitting units are projected onto the corresponding photosensitive units.

[0023] The image sensor and the meta-lens are arranged at intervals along the thickness direction of the camera module. They are parallel to each other and face each other. The distance between them is the focal length of the meta-lens, which is beneficial for the miniaturization of the camera module.

[0024] In some possible implementations, the metalens can employ a lateral vertical-axis focusing method to converge light rays, thereby improving focusing efficiency. In this case, the photosensitive unit of the image sensor can be offset relative to the beam-splitting unit of the metalens by a certain distance. Understandably, the offset of the photosensitive unit relative to the beam-splitting unit is very small. In some implementations, the photosensitive unit can also be directly aligned with the beam-splitting unit without any offset.

[0025] Among them, the lateral off-axis distance of the focused beam after passing through the meta-lens is greater than 0 and can be less than or equal to 20μm.

[0026] In some possible implementations, a beam-splitting unit is used to divide the light beam into N sub-beams according to wavelength. The photosensitive unit corresponding to the beam-splitting unit includes M pixels, where N and M are both positive integers, and M > N. In this case, the photosensitive unit can receive and identify all the sub-beams, thereby forming a relatively complete spectral information of the subject.

[0027] In this system, the image sensor is a monochrome sensor. A metalens divides the light beam into multiple sub-beams according to wavelength. Multiple pixels in the photosensitive unit receive these sub-beams, forming a grayscale image. The electronic device combines pixels with the same spectral information to create an image, ultimately forming a multispectral image.

[0028] In some possible implementations, the beam splitting unit is used to split the light beam with a wavelength range of 450nm to 950nm into 10 to 30 sub-beams. In this case, the spectral resolution of the camera module is 20nm. In this implementation, the camera module has a wide identifiable spectral range, covering the visible and near-infrared bands.

[0029] In some possible implementations, the camera module also includes a motor, a base, and a circuit board. The motor and the circuit board are fixed on opposite sides of the base, the lens is mounted on the motor, the image sensor is fixed on the circuit board, and the meta-lens is fixed on the base or the circuit board.

[0030] In some possible implementations, the camera module also includes a base and a circuit board, with the lens and circuit board fixed on opposite sides of the base, the image sensor fixed to the circuit board, and the meta-lens fixed to the base or circuit board.

[0031] Secondly, this application also provides an electronic device, including a processor and a camera module of any of the above, wherein the processor is communicatively connected to the camera module, and the processor is used to acquire image data from the camera module and process the image data.

[0032] In this application, the camera module is a spectral camera used to record the two-dimensional spatial and spectral information of the photographed object. Users can achieve a superior shooting experience through the spectral camera. For example, users can take photos of various everyday items, and through image post-processing algorithms, in addition to obtaining highly realistic photos (using spectral information to calibrate color restoration), the electronic device can also combine spectral information and a database to promptly detect the material and corresponding component ratios (such as sugar content, protein, and fat content) of the item, facilitating users' daily lives and improving the user experience. The electronic device may also include other camera modules, such as a wide-angle camera module, a telephoto camera module, and a color main camera module, to facilitate the acquisition of the spatial position, color, and light intensity of the photographed object, thereby obtaining better image quality and a better shooting experience. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the electronic device provided in some embodiments of this application;

[0034] Figure 2 yes Figure 1 The diagram shows a structural schematic of a camera module in some embodiments.

[0035] Figure 3 yes Figure 2 A partial exploded view of the camera module shown.

[0036] Figure 4 yes Figure 2 The diagram shows the internal structure of the camera module.

[0037] Figure 5 yes Figure 4 The diagram shows the optical path of the camera module shown.

[0038] Figure 6 yes Figure 4 A schematic diagram of the metalens and image sensor of the camera module shown;

[0039] Figure 7 yes Figure 5 The diagram shows a structural schematic of the metalens in some embodiments;

[0040] Figure 8 This application provides an optimization algorithm for the outer diameter of the cylindrical body of a meta-lens;

[0041] Figure 9 Through Figure 8 The optimization algorithm shown presents a distribution of the radius sizes of multiple cylinders located in the same row of a possible metalens.

[0042] Figure 10 It corresponds to Figure 9 The focusing efficiency curve of the metalens;

[0043] Figure 11 It corresponds to Figure 9 A schematic diagram of the transmission effect of the metalens;

[0044] Figure 12 yes Figure 5 The diagram shows a structural schematic of the metalens in some other embodiments;

[0045] Figure 13 Through Figure 8 The optimization algorithm shown presents a distribution of the radius sizes of multiple cylinders in the same row of another possible meta-lens.

[0046] Figure 14 It corresponds to Figure 13 The focusing efficiency curve of the metalens;

[0047] Figure 15 It corresponds to Figure 13 A schematic diagram of the transmission effect of the metalens;

[0048] Figure 16 yes Figure 6 The diagram shows a structural schematic of the metalens in some embodiments;

[0049] Figure 17 yes Figure 1 The diagram shows a partial exploded view of the camera module in some other embodiments;

[0050] Figure 18 yes Figure 17 The diagram shows the internal structure of the camera module.

[0051] Figure 19 yes Figure 17 A schematic diagram of the metalens structure of the camera module shown. Detailed Implementation

[0052] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; the word "and / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0053] In the following text, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0054] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection", "linking", and "set on" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0055] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of the electronic device 100 provided in some embodiments of this application. The electronic device 100 can be a mobile phone, tablet personal computer, laptop computer, personal digital assistant (PDA), camera, personal computer, laptop computer, in-vehicle equipment, wearable device, augmented reality (AR) glasses, AR helmet, virtual reality (VR) glasses, or VR helmet, etc., that has a camera module. Figure 1 The electronic device 100 of the illustrated embodiment is described using a mobile phone as an example.

[0056] The electronic device 100 includes a housing 10, a display screen (not shown), a processor 20, and a camera module 30. In some embodiments, the housing 10 includes a frame 101 and a back cover 102. The frame 101 and the back cover 102 can be a single molded structure or can be assembled into a single structure. The display screen and the back cover 102 are respectively mounted on both sides of the frame 101.

[0057] The processor 20 and the camera module 30 are housed inside the housing 10. The processor 20 is communicatively connected to the camera module 30, and is used to acquire and process image data from the camera module 30. The communication connection between the camera module 30 and the processor 20 can include data transmission via electrical connections such as wiring, or via coupling. It is understood that the camera module 30 and the processor 20 can also be connected via other methods capable of data transmission.

[0058] In this embodiment, the rear cover 102 is provided with a camera hole 103, through which the camera module 30 can collect light to serve as a rear camera of the electronic device 100. For example, the rear cover 102 includes a light-transmitting lens mounted on the camera hole 103 to allow light to pass through and to provide dust and water resistance. In other embodiments, the camera module 30 can also serve as a front camera of the electronic device 100.

[0059] In this embodiment, the camera module 30 can be a spectral camera, which records the two-dimensional spatial information and spectral information of the photographed object. Users can achieve a better shooting experience through the spectral camera. For example, users can take pictures of various everyday items. Through image post-processing algorithms, in addition to obtaining very realistic photos (using spectral information to calibrate color restoration), the electronic device 100 can also combine spectral information and a database to promptly detect the material and corresponding component ratios (such as sugar content, protein, and fat content) of the item, facilitating users' daily lives and improving their user experience. The electronic device 100 may also include other camera modules, such as a wide-angle camera module, a telephoto camera module, and a color main camera module, to facilitate the acquisition of the spatial position, color, and light intensity of the photographed object, thereby obtaining better image quality and a better shooting experience.

[0060] Understandable, Figure 1 The installation position of the camera module 30 in the illustrated embodiment of the electronic device 100 is merely illustrative, and this application does not strictly limit the installation position of the camera module 30. In some other embodiments, the camera module 30 may also be installed in other locations on the electronic device 100, such as the upper center or upper right corner of the back of the electronic device 100. In some other embodiments, the electronic device 100 may include a device body and auxiliary components that can rotate, move, or be detached relative to the device body, and the camera module 30 may also be disposed on the auxiliary components.

[0061] Please refer to the following: Figures 2 to 4 , Figure 2 yes Figure 1 The diagram shown is a structural schematic of the camera module 30 in some embodiments. Figure 3 yes Figure 2 A partially exploded view of the camera module 30 shown. Figure 4 yes Figure 2 The diagram shows the internal structure of the camera module 30.

[0062] In some embodiments, the camera module 30 includes a lens 1, a motor 2, a holder 3, an image sensor 4, a circuit board 5, a meta-lens 6, and a filter 7. The lens 1 may include a lens barrel and a lens group mounted inside the lens barrel. The lens 1 is mounted on the motor 2, which is fixed to one side of the holder 3. The motor 2 may be a focusing motor and / or an optical image stabilization motor, used to drive the lens 1 to move or tilt. In this embodiment, the camera module 30 is an autofocus module and / or an optical image stabilization module.

[0063] For example, circuit board 5 is fixed to the other side of base 3, that is, motor 2 and circuit board 5 are fixed to both sides of base 3 respectively. Image sensor 4 is located on the image side of lens 1, and image sensor 4 can be fixed to circuit board 5. Here, image sensor 4 (also called photosensitive element) is a semiconductor chip with hundreds of thousands to millions of photodiodes on its surface, which generate charges when exposed to light. Image sensor 4 can be a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) device.

[0064] For example, the meta-lens 6 is located between the lens 1 and the image sensor 4, and the meta-lens 6 can be fixed to the base 3 or the circuit board 5. The meta-lens 6 can be used to split a light beam with a wavelength range of 450nm to 950nm.

[0065] For example, the filter 7 is located between the lens 1 and the metalens 6. Light from outside the camera module 30 is projected onto the image sensor 4 after passing through the lens 1, the filter 7, and the metalens 6. The filter 7 is used to eliminate unwanted light projected onto the image sensor 4, preventing the image sensor 4 from producing false colors or ripples, thereby improving its effective resolution and color reproduction. For example, the filter 7 is used to filter infrared light. For example, the filter 7 may include a substrate and a filter film fixed to the substrate. The substrate may be made of sapphire, the main component of which is aluminum oxide (Al2O3). The filter film may include an infrared cut-off film. For example, the infrared cut-off film is used to filter infrared light with wavelengths greater than 950 nm. In some embodiments, the filter film may also include an ultraviolet cut-off film so that the filter 7 is also used to filter ultraviolet light.

[0066] The filter 7 can be fixed to the base 3. Exemplarily, the metalens 6 is also fixed to the base 3, and the filter 7 can be spaced apart from the metalens 6. For example, the base 3 includes a first limiting surface and a second limiting surface. The first limiting surface is located between the lens 1 and the second limiting surface and is spaced apart from the second limiting surface. The first limiting surface faces the lens 1, and the second limiting surface faces away from the lens 1. The filter 7 is fixed to the first limiting surface, and the metalens 6 is fixed to the second limiting surface. In some other embodiments, the filter 7 and the metalens 6 may also be in contact; this is not strictly limited in this embodiment. In some other embodiments, the metalens 6 may also be fixed to the circuit board 5. For example, the camera module 30 also includes a bracket, which is fixed to the circuit board 5. The metalens 6 is fixed to the bracket, and the image sensor 4 is located below the metalens 6.

[0067] In some other embodiments, the camera module 30 may not include the motor 2, and the lens 1 may be directly fixed to the base 3. That is, the lens 1 and the circuit board 5 are respectively fixed to the two sides of the base 3. In this embodiment, the camera module 30 is a fixed-focus module.

[0068] In this embodiment, the camera module 30 has a length direction, a width direction, and a thickness direction. The width direction is perpendicular to the length direction, and the thickness direction is perpendicular to both the width and length directions. The optical axis of the lens 1 is parallel to the thickness direction of the camera module 30. The optical axis of the lens 1 refers to the line at the center of the lens 1.

[0069] Please see Figure 5 and Figure 6 , Figure 5 yes Figure 4 The diagram shows the optical path of the camera module 30. Figure 6 yes Figure 4 A schematic diagram of the meta-lens 6 and image sensor 4 of the camera module 30 shown.

[0070] In some embodiments, lens 1 focuses the reflected light from the subject onto a meta-lens 6. The meta-lens 6 includes a meta-surface structure. The light resonates with the meta-surface structure, causing phase delay and phase modulation of the outgoing wavefront. Light of different wavelengths is dispersed, thus the meta-lens 6 can divide the light into multiple channels according to wavelength and then focus it onto the image sensor 4. The image sensor 4 converts the optical signal into an electrical signal. The processor 20 of the electronic device 100 processes the electrical signal to obtain the two-dimensional spatial information and spectral information of the subject.

[0071] In this embodiment, since the camera module 30 achieves light field imaging and multispectral imaging by setting the metalens 6, a single lens 1 can be used to collect the reflected light from the object being photographed. There is no need to use components such as prisms as beam splitters, resulting in high image overlap accuracy and high imaging quality in the captured multispectral images. At the same time, the optical system of the camera module 30 has few components and a simple composition, making the camera module 30 low-cost and small in size.

[0072] For example, the meta-lens 6 includes a substrate 61 and a plurality of pillars 62. The plurality of pillars 62 are fixed to the side of the substrate 61 facing the image sensor 4. Each pillar 62 is a rotationally symmetric structure with a rotation angle of 90°. In this embodiment, the pillars 62 of the meta-lens 6 adopt a rotationally symmetric structure with a rotation angle of 90°. Therefore, the optical system of the camera module 30 using this meta-lens 6 is a polarization-independent system.

[0073] In a spectroscopic camera system that relies on the polarization characteristics of the light source, linear polarizers and quarter-wave plates need to be added to the incident light side of the metalens, and also to the emitting light side. Furthermore, due to the short focal length of the metalens, linear polarizers and quarter-wave plates cannot be directly accommodated between the image sensor and the metalens. Therefore, an objective lens is needed as a relay system on the emitting light side of the metalens to solve this problem. Thus, a spectroscopic camera system requires at least two linear polarizers, two quarter-wave plates, and an objective lens. This not only severely reduces the light transmittance of the spectroscopic camera system (below 25%), but also greatly increases the complexity of the system, hindering its integration and application in small electronic devices (such as portable devices).

[0074] In this embodiment, since the optical system of the camera module 30 is a polarization-independent system, the optical system does not need to be equipped with components such as linear polarizers and quarter-wave plates. The composition of the optical system is simple and the components are arranged compactly. Therefore, the camera module 30 is small in size and can be well applied to small electronic devices 100.

[0075] Furthermore, since the height of the microstructure (i.e., the column 62) of the metasurface structure is on the order of single-digit micrometers, the overall volume of the meta lens 6 is very small, which reduces the structural design difficulty of the camera module 30 and makes the camera module 30 small in size, which is beneficial for the application of the camera module 30 in miniaturized electronic devices 100.

[0076] In some embodiments, such as Figure 5 and Figure 6 As shown, the meta-lens 6 has multiple beam-splitting units 63 arranged in an array. Each beam-splitting unit 63 is used to divide the beam into multiple sub-beams according to the wavelength and project them onto the image sensor 4. Figure 5Different line shapes are used to illustrate some of the sub-beams. For example, the image sensor 4 includes multiple photosensitive units 41 arranged in an array, with each photosensitive unit 41 corresponding to a multiple beam-splitting unit 63. The sub-beams formed by the beam-splitting unit 63 are projected onto the corresponding photosensitive unit 41.

[0077] For example, see reference Figure 4 The image sensor 4 and the metalens 6 are arranged at intervals along the thickness direction of the camera module 30, parallel to each other and directly opposite each other. The distance between them is the focal length of the metalens 6, which is beneficial for the miniaturization of the camera module 30. The metalens 6 can use a lateral vertical axis focusing method to converge light, thereby improving focusing efficiency. In this case, the photosensitive unit 41 of the image sensor 4 can be offset relative to the beam-splitting unit 63 of the metalens 6 by a certain distance. It is understood that the offset of the photosensitive unit 41 relative to the beam-splitting unit 63 is very small. In some embodiments, the photosensitive unit 41 can also be directly opposite the beam-splitting unit 63 without offset.

[0078] In some embodiments, such as Figure 5 and Figure 6 As shown, multiple beam-splitting units 63 are arranged in rows along a first direction X and in columns along a second direction Y. One of the first direction X and the second direction Y is parallel to the length direction of the camera module 30, and the other is parallel to the width direction of the camera module 30. Multiple photosensitive units 41 are also arranged in rows along the first direction X and in columns along the second direction Y. In the plane containing the first direction X and the second direction Y, the beam-splitting units 63 and the photosensitive units 41 have the same shape, and the size of the beam-splitting units 63 is equal to or larger than the size of the photosensitive units 41.

[0079] For example, the beam splitting unit 63 is used to divide the light beam into N sub-beams according to wavelength. The photosensitive unit 41 corresponding to the beam splitting unit 63 includes M pixels, where N and M are both positive integers, and M > N. At this time, the photosensitive unit 41 can receive and identify all the sub-beams, thereby forming a relatively complete spectral information of the subject. The image sensor 4 is a monochrome sensor. After the meta-lens 6 divides the light beam into multiple sub-beams according to wavelength, the multiple pixels of the photosensitive unit 41 receive the multiple sub-beams and form a grayscale image. The electronic device 100 combines pixels with the same spectral information into an image, ultimately forming a multispectral image. The center distance between two adjacent pixels can be 1 μm, but this embodiment does not strictly limit this.

[0080] For example, the beam splitting unit 63 is used to split a light beam with a wavelength range of 450nm to 950nm, and can split it into 10 to 30 sub-beams. For instance, the beam splitting unit 63 can split the light beam into 25 sub-beams. In this case, the spectral resolution of the camera module 30 is 20nm. In this embodiment, the camera module 30 has a wide identifiable spectral range, covering the visible light and near-infrared bands.

[0081] In this application, the structures of the multiple beam-splitting units 63 of the meta-lens 6 can be different while meeting the requirements of beam splitting and focusing. One of the beam-splitting units will be described below.

[0082] Please see Figure 7 , Figure 7 yes Figure 5 The diagram shows the structure of the meta-lens 6 in some embodiments.

[0083] In some embodiments, the plurality of beam-splitting units 63 includes a first beam-splitting unit 63a. The first beam-splitting unit 63a is square in shape on the plane containing the first direction X and the second direction Y, and its side length can be in the range of 30μm to 100μm, for example, 35μm, 42μm, 58μm, etc. In this case, the photosensitive unit 41 of the image sensor 4 corresponding to the first beam-splitting unit 63a is also in the positive direction, so as to receive the sub-beams emitted by the first beam-splitting unit 63a.

[0084] In the first beam-splitting unit 63a, multiple pillars 62 are arranged in a row along a first direction X and in a column along a second direction Y. Each pillar 62 extends along a third direction Z, which is perpendicular to both the first and second directions X and Y. The cross-sectional shape of each pillar 62 can be circular, and each pillar 62 is a cylinder. At least some of the pillars 62 in the same row have different outer diameters (i.e., the diameter of the pillar 62), while multiple pillars 62 in the same column have the same outer diameter. The first beam-splitting unit 63a is used to split the light beam into multiple sub-beams along the first direction X according to wavelength, and project them onto the image sensor 4. Each sub-beam is not split in the second direction Y.

[0085] In the first beam-splitting unit 63a, multiple pillars 62 are arranged at equal intervals in the first direction X, with a spacing S1 ranging from 150nm to 300nm, such as 180nm, 200nm, and 235nm; the multiple pillars 62 are also arranged at equal intervals in the second direction Y, with a spacing S2 ranging from 150nm to 300nm, such as 180nm, 200nm, and 235nm. The spacing between two pillars 62 refers to the center-to-center distance between the two pillars 62.

[0086] The height h1 of the pillar 62 in the third direction Z can be in the range of 500nm to 2000nm, for example, 800nm. The outer diameter of the pillar 62 can be in the range of 40nm to 200nm. The pillar 62 can be made of semiconductor materials, such as gallium nitride, titanium dioxide, or silicon nitride.

[0087] The substrate 61 of the metalens 6 can be made of silicon dioxide or sapphire. The height h2 of the substrate 61 in the third direction Z can be in the range of 100μm to 500μm, for example, 180μm, 210μm, or 320μm. The third direction Z is perpendicular to the first direction X and the second direction Y. Since the height of the column 62 of the metalens 6 is very small, the main thickness of the metalens 6 is formed by the substrate 61. When the thickness of the substrate 61 is less than 500μm, the thickness of the metalens 6 is very small, which is beneficial to the miniaturization of the camera module 30.

[0088] In this embodiment of the application, by designing the outer diameter of the multiple columns 62 located in the same row of the first beam splitting unit 63a, the first beam splitting unit 63a can divide the light beam into multiple sub-beams according to the wavelength, and the multiple sub-beams are projected along the first direction X onto different positions of the photosensitive unit 41 of the corresponding image sensor 4.

[0089] Please see Figure 8 , Figure 8 This application provides an optimization algorithm for the outer diameter of the cylinder 62 of a meta-lens 6.

[0090] In some embodiments, the outer diameter dimensions of the plurality of pillars 62 located in the same row of the first spectroscopic unit 63a can be obtained using a genetic algorithm. Specifically:

[0091] First, the finite element time-domain (FDTD) method software was used to scan cylindrical unit structures (including cylinder 62 and the corresponding substrate 61) with diameters ranging from 40 nm to 200 nm, obtaining the transmittance and phase compensation amount when the light field passes through different cylindrical unit structures. After obtaining the transmittance and phase compensation amount, a genetic algorithm was used to optimize the outer diameter distribution of the multiple cylinders 62 of the metalens 6.

[0092] For example, the flow of a genetic algorithm embodiment is as follows:

[0093] Step S01: Randomly generate multiple column arrays (i.e., a population). Each column array includes multiple columns arranged in an array; the multiple columns are arranged in rows with equal spacing of 200 nm along a first direction; multiple columns in the same row are arranged in columns with equal spacing of 200 nm along a second direction. The number of columns arranged in the same row is 210, and at least some of the 210 columns have different outer diameters. The number of columns arranged in the same column is 210, and all columns have the same outer diameter.

[0094] Step S02: Calculate the focusing efficiency of multiple cylindrical arrays. Using angular spectrum theory, calculate the efficiency of incident light of different wavelengths when focused onto a specific position on the image sensor after passing through a metalens. Take the average focusing efficiency at different wavelengths as the evaluation function, and calculate the focusing efficiency of multiple cylindrical arrays respectively. The transmittance and phase compensation of different cylindrical sub-unit structures are used as quantitative inputs to the angular spectrum theory.

[0095] Step S03: Replace part of the column array. Sort the focusing efficiency of multiple column arrays by size, eliminate a certain proportion of column arrays with lower focusing efficiency, and then copy a certain proportion of column arrays with higher focusing efficiency for replacement, so that the total number of column arrays remains unchanged.

[0096] Step S04: Initialize the columns in a random region of the column array, or swap the columns in the same random region of two column arrays. The process of initializing the outer diameter of the columns in a random region of the column array can be called "gene" mutation; the process of swapping the columns in a random, identical region of any two column arrays can be called "gene" hybridization. Through "gene" mutation and hybridization, it is possible to produce superior individuals in the population and to generate column arrays with higher focusing efficiency.

[0097] Step S05: Calculate and sort the focusing efficiency of multiple column arrays, and determine whether the maximum value reaches the set evaluation function target value. If the set evaluation function target value is reached, the optimization process terminates; otherwise, skip to step S03 to continue optimization until the target value is met before terminating the optimization process.

[0098] Please see Figure 9 , Figure 9 Through Figure 8 The optimization algorithm shown presents a distribution diagram of the radius sizes of multiple cylinders 62 located in the same row of a possible metalens 6. Figure 9 In the diagram, the horizontal axis represents the column number of the superlens 6 in the first direction, and the vertical axis represents the corresponding radius. For example... Figure 9As shown, in some embodiments, in the first beam splitting unit 63a, the outer diameter (i.e., twice the radius) of multiple pillars 62 in the same row is distributed in an oblique trapezoidal aperiodic pattern. Specifically, if more than half of the pillars 62 in the same row satisfy the oblique trapezoidal aperiodic distribution in their outer diameter, then the outer diameter of the multiple pillars 62 in the same row can be considered to be distributed in an oblique trapezoidal aperiodic pattern.

[0099] Please see Figure 10 , Figure 10 It corresponds to Figure 9 The focusing efficiency curve of the superlens 6. Figure 10 In the graph, the horizontal axis represents wavelength (nm), and the vertical axis represents focusing efficiency at different light wavelengths. Figure 10 It is known that the focusing efficiency of the meta-lens 6 varies in different wavelength ranges within the 450nm to 950nm band: the focusing efficiency in the 550nm to 750nm band is relatively high, while the focusing efficiency in other bands is relatively low. However, the overall average efficiency can reach as high as 55%, which is much higher than that of the spectral camera system based on polarization-dependent design. Therefore, the focusing efficiency of the optical system of the camera module 30 in this embodiment is high.

[0100] Please see Figure 11 , Figure 11 It corresponds to Figure 9 A schematic diagram of the transmission effect of the superlens 6. Figure 11 The image shows light beams with wavelengths of 450 nm, 550 nm, 650 nm, 750 nm, 850 nm, and 950 nm, corresponding to... Figure 9 The transmission effect of the superlens 6. Figure 11 The horizontal axis represents the coordinates in the first direction, and the vertical axis represents the coordinates in the third direction. For example, the meta-lens 6 employs a lateral off-axis focusing method to improve focusing efficiency. Figure 11 As shown, the light field is focused at the focal plane z = 200 μm after passing through the metalens 6. All wavelengths of the light field undergo lateral off-axis focusing, and the sub-beams of different wavelengths are staggered in the first direction. The lateral off-axis distance of the focused beam after passing through the metalens 6 is greater than 0 and can be less than or equal to 20 μm.

[0101] Please see Figure 12 , Figure 12 yes Figure 5The diagram shows a structural schematic of the meta-lens 6 in some other embodiments. This embodiment includes most of the features of the previous embodiments. The main difference between this embodiment and the previous embodiments is that in the first beam-splitting unit 63a, the cross-sectional shape of the column 62 can be square, and the column 62 is a cube. The outer diameter of the column 62 is the side length of the column 62. The outer diameters of multiple columns 62 arranged in the same row can also be determined by... Figure 8 The corresponding optimization algorithm is obtained. In this embodiment, the other design of the first beam splitter 63a is described in the previous embodiment and will not be repeated here.

[0102] Please see Figure 13 , Figure 13 Through Figure 8 The diagram shows the radius distribution of multiple cylinders 62 located in the same row of another possible meta-lens 6 obtained by the optimization algorithm shown. Figure 13 In the diagram, the horizontal axis represents the column number of the superlens 6 in the first direction, and the vertical axis represents the corresponding radius. For example... Figure 13 As shown, in some embodiments, in the first beam splitting unit 63a, the outer diameter (i.e., twice the radius) of a plurality of pillars 62 in the same row is distributed in an oblique trapezoidal aperiodic pattern.

[0103] Please see Figure 14 , Figure 14 It corresponds to Figure 13 The focusing efficiency curve of the superlens 6. Figure 14 In the graph, the horizontal axis represents wavelength (nm), and the vertical axis represents focusing efficiency at different light wavelengths. Figure 14 It is known that the focusing efficiency of the meta-lens 6 varies across different wavelength ranges in the 450nm to 950nm band: the focusing efficiency is relatively high in the 500nm to 800nm ​​band and relatively low in the edge band, but the overall average efficiency can reach as high as 51%, which is much higher than that of the spectral camera system based on polarization-dependent design. Therefore, the focusing efficiency of the optical system of the camera module 30 in this embodiment is high.

[0104] Please see Figure 15 , Figure 15 It corresponds to Figure 13 A schematic diagram of the transmission effect of the superlens 6. Figure 15 The image shows light beams with wavelengths of 450 nm, 550 nm, 650 nm, 750 nm, 850 nm, and 950 nm, corresponding to... Figure 13 The transmission effect of the superlens 6. Figure 15 The horizontal axis represents the coordinates in the first direction, and the vertical axis represents the coordinates in the third direction. For example, the meta-lens 6 employs a lateral off-axis focusing method to improve focusing efficiency. Figure 15As shown, the light field is focused at the focal plane z = 200 μm after passing through the metalens 6. All wavelengths of the light field undergo lateral off-axis focusing, and the sub-beams of different wavelengths are staggered in the first direction. The lateral off-axis distance of the focused beam after passing through the metalens 6 is greater than 0 and can be less than or equal to 20 μm.

[0105] In some other embodiments, the cross-sectional shape of the column 62 in the first beam splitting unit 63a can also be an octagon or other shape that satisfies rotational symmetry with a rotation angle of 90°. This application does not strictly limit this. Wherein, when the cross-sectional shape of the column 62 is octagonal, the outer diameter of the column 62 is the distance between two opposite sides.

[0106] Please see Figure 16 , Figure 16 yes Figure 6 The diagram shows the structure of the meta-lens 6 in some embodiments.

[0107] In some embodiments, the multiple beam-splitting units 63 of the meta-lens 6 further include a second beam-splitting unit 63b. The second beam-splitting unit 63b is used to split the light beam into multiple sub-beams along the second direction Y according to the wavelength band and project them onto the image sensor 4. In the second beam-splitting unit 63b, multiple pillars 62 are arranged in a row along the first direction X and in a column along the second direction Y. Each pillar 62 is a rotationally symmetric structure with a rotation angle of 90°. The outer diameters of the multiple pillars 62 in the same row are the same, while the outer diameters of at least some of the pillars 62 in the same column are different. The structural design of the second beam-splitting unit 63b is the same as that of the first beam-splitting unit 63a, the difference being that the beam splitting directions are different. For example, the second beam-splitting unit 63b can adopt the structure of the first beam-splitting unit 63a rotated by 90°.

[0108] The number of first beam splitting units 63a can be multiple, and the number of second beam splitting units 63b can also be multiple. The multiple first beam splitting units 63a and the multiple second beam splitting units 63b can be arranged in an alternating manner, including but not limited to: alternating arrangement in the first direction X and / or alternating arrangement in the second direction Y.

[0109] In some other embodiments, the beam-splitting directions of the plurality of beam-splitting units 63 of the meta-lens 6 may also be consistent, and this application embodiment does not strictly limit this.

[0110] Please refer to the following: Figures 17 to 19 , Figure 17 yes Figure 1 The diagram shows a partial exploded view of the camera module 30 in some other embodiments. Figure 18 yes Figure 17 A schematic diagram of the internal structure of the camera module 30 shown. Figure 19 yes Figure 17The diagram shows the structure of the metalens 6 in the camera module 30. The camera module 30 in this embodiment includes most of the technical features of the camera module 30 in the previous embodiment. Most of the content that is the same in both will not be repeated. The main difference is that the camera module 30 in this embodiment does not have a separate filter; the filtering function is integrated by the metalens 6.

[0111] For example, the camera module 30 includes a lens 1, a motor 2, a holder 3, an image sensor 4, a circuit board 5, and a metalens 6. The metalens 6 includes a substrate 61 and multiple pillars 62, which are fixed to the side of the substrate 61 facing the image sensor 4. Each pillar 62 is rotationally symmetric with a rotation angle of 90°. The metalens 6 also includes a filter film 64, which is fixed to the side of the substrate 61 facing away from the multiple pillars 62. The filter film 64 is used to eliminate unwanted light projected onto the image sensor 4, preventing the image sensor 4 from producing false colors or ripples, thereby improving its effective resolution and color reproduction. For example, the filter film 64 is used to filter infrared light. The filter film 64 may include an infrared cutoff film for filtering infrared light with wavelengths greater than 950 nm. In some embodiments, the filter film 64 may also include an ultraviolet cutoff film for filtering ultraviolet light.

[0112] In this embodiment, since the meta-lens 6 integrates a light filtering function while achieving the functions of beam splitting and focusing, the camera module 30 does not need to be equipped with a light filter, which simplifies the component composition of the camera module 30 and makes the thickness of the camera module 30 smaller, which is beneficial to the miniaturization of the camera module 30 and the electronic device 100 that uses the camera module 30.

[0113] In this embodiment, the camera module implements a spectral camera system based on a polarization-independent metalens. Compared to traditional camera modules, in addition to information such as the intensity, position, and color of the incident light, it can also obtain the spectral information of the object being photographed. The camera module uses a metalens to achieve multispectral imaging, which can recognize a wide spectral range, reaching 450nm to 950nm, covering the visible and near-infrared bands. It also has good temporal performance, obtaining the object's spectral information in a single shot. Furthermore, the camera module has a simple module structure and advantages such as miniaturization, easy integration, low power consumption, and low cost, making it suitable for terminal devices such as smartphones.

[0114] In other embodiments, by designing the metasurface structure of the metalens, the camera module can be used in more application scenarios, such as polarization imaging and holography.

[0115] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A camera module (30), characterized by, The camera lens comprises a lens (1), an image sensor (4) and a metasurface lens (6). The image sensor (4) is located on the image side of the lens (1), and the metasurface lens (6) is located between the lens (1) and the image sensor (4). The metasurface lens (6) comprises a substrate (61) and a plurality of columns (62). The plurality of columns (62) are fixed to one side of the substrate (61) facing the image sensor (4). Each column (62) is a rotationally symmetric structure with a rotation angle of 90°. The metasurface lens (6) has a plurality of light splitting units (63) arranged in an array. The plurality of light splitting units (63) comprise a first light splitting unit (63a) for splitting a light beam into a plurality of sub-beams according to wave bands along a first direction and projecting the sub-beams on the image sensor (4). In the first light splitting unit (63a), the plurality of columns (62) are arranged in a row along the first direction and in a column along a second direction perpendicular to the first direction. The outer diameters of at least some columns (62) in the same row are different, and the outer diameters of the plurality of columns (62) in the same column are the same. The transverse off-axis distance of the focused light beam passing through the metasurface lens (6) is greater than 0 and less than or equal to 20 μm. The image sensor (4) comprises a plurality of light sensing units (41). The plurality of light sensing units (41) are arranged one-to-one with the plurality of light splitting units (63). The sub-beams formed by the light splitting units (63) are projected on the corresponding light sensing units (41).

2. The camera module (30) according to claim 1, characterized in that In the first light splitting unit (63a), the columns (62) extend along a third direction perpendicular to the first direction and the second direction. The cross-sectional shape of the columns (62) is circular, square or octagonal.

3. The camera module (30) of claim 1, wherein, In the first light splitting unit (63a), the plurality of columns (62) are equally spaced in the first direction with a spacing in the range of 150 nm to 300 nm, and the plurality of columns (62) are equally spaced in the second direction with a spacing in the range of 150 nm to 300 nm; or, The height of the columns (62) in the third direction is in the range of 500 nm to 2000 nm, and the third direction is perpendicular to the first direction and the second direction; or, The outer diameter of the columns (62) is in the range of 40 nm to 200 nm; or, The columns (62) are made of a semiconductor material.

4. The camera module (30) according to claim 3, characterized in that In the first light splitting unit (63a), the outer diameters of the plurality of columns (62) in the same row are distributed in a diagonal stepped non-periodic manner.

5. The camera module (30) of claim 1, wherein, The substrate (61) is made of silica or sapphire; or, the height of the substrate (61) in the third direction is in the range of 100 μm to 500 μm, and the third direction is perpendicular to the first direction and the second direction.

6. The camera module (30) according to any one of claims 1 to 5, characterized in that The plurality of light splitting units (63) further include a second light splitting unit (63b) configured to split a light beam into a plurality of sub-beams along the second direction according to wave bands and project the sub-beams on the image sensor (4). In the second light splitting unit (63b), the plurality of columns (62) are arranged in rows along the first direction and arranged in columns along the second direction, each column (62) is a rotationally symmetric structure with a rotation angle of 90°, the outer diameters of the columns (62) in the same row are the same, and the outer diameters of at least some of the columns (62) in the same column are different.

7. The camera module (30) according to any one of claims 1 to 5, characterized in that The meta-lens (6) further includes a light filter film (64) fixed to one side of the substrate (61) away from the plurality of columns (62), and the light filter film (64) is configured to filter infrared rays.

8. The camera module (30) according to any one of claims 1 to 5, characterized in that The camera module (30) further includes a light filter (7) located between the lens (1) and the meta-lens (6), and the light filter (7) is configured to filter infrared rays.

9. The camera module (30) according to claim 8, characterized in that The light splitting unit (63) is configured to split a light beam into N sub-beams according to wave bands, and the light sensing unit (41) corresponding to the light splitting unit (63) includes M pixels, wherein N and M are positive integers, and M>N.

10. The camera module (30) according to any one of claims 1 to 5, characterized in that The light splitting unit (63) is configured to split a light beam with a wavelength range of 450nm to 950nm into 10 to 30 sub-beams.

11. The camera module (30) according to any one of claims 1 to 5, characterized in that The camera module (30) further includes a motor (2), a base (3), and a circuit board (5), the motor (2) and the circuit board (5) are fixed to two sides of the base (3) respectively, the lens (1) is installed on the motor (2), the image sensor (4) is fixed to the circuit board (5), and the meta-lens (6) is fixed to the base (3) or the circuit board (5); or, The camera module (30) further includes a base (3) and a circuit board (5), the lens (1) and the circuit board (5) are fixed to two sides of the base (3) respectively, the image sensor (4) is fixed to the circuit board (5), and the meta-lens (6) is fixed to the base (3) or the circuit board (5).

12. An electronic device (100), characterized by The camera module (30) includes a processor (20) and the camera module (30) of any one of claims 1 to 11, the processor (20) is in communication connection with the camera module (30), and the processor (20) is configured to acquire image data from the camera module (30) and process the image data.

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