Optical imaging lens and eye movement tracking device

Abstract

This invention provides an optical imaging lens and an eye-tracking device having the optical imaging lens. The optical imaging lens includes an optical lens group and an imaging detector. The optical lens group includes an object-side surface facing the object, an image-side surface facing the image, and an outer peripheral surface located between the object-side surface and the image-side surface of the optical lens group. The imaging detector is connected to the image-side surface of the optical lens group. The invention is characterized in that all optical lenses in the optical lens group are metasurface lenses. The optical imaging lens also includes an anti-interference layer formed on the outer peripheral surface, which is used to isolate ambient light. Using an anti-interference layer instead of the lens barrel or light shield in the prior art does not increase the overall size of the optical imaging lens, which is beneficial for the miniaturization design of the optical imaging lens.

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 eye-tracking device. Background Technology

[0002] Eye-tracking technology has been widely used in virtual reality (VR), augmented reality (AR), medical diagnosis, and human-computer interaction in recent years. Its core principle is to capture eye movement information through optical imaging lenses to achieve high-precision gaze tracking. However, despite significant technological advancements, eye-tracking optical imaging lenses still face a key challenge in practical applications: the system size is too large, making it difficult to meet the needs of miniaturized devices. For example, traditional optical imaging lenses, to avoid the influence of ambient light on the final image, typically have a lens barrel surrounding the lens group, increasing the size and complexity of the optical imaging lens and limiting its miniaturization potential. Utility Model Content

[0003] The purpose of this invention is to provide an optical imaging lens and an eye-tracking device.

[0004] To achieve the above-mentioned utility model objectives, the present utility model adopts the following technical solution: an optical imaging lens, comprising an optical lens group and an imaging detector, wherein the optical lens group includes an object-side surface facing the object side, an image-side surface facing the image side, and an outer peripheral surface located between the object-side surface and the image-side surface of the optical lens group, and the imaging detector is connected to the image-side surface of the optical lens group; all optical lenses in the optical lens group are metasurface lenses; the optical imaging lens further includes an anti-interference layer, which is formed on the outer peripheral surface and is used to isolate ambient light.

[0005] As a further improvement of this utility model, the circumferential dimension of the outer peripheral surface of the optical lens group is smaller than the circumferential dimension of the imaging detector in the circumferential direction; the anti-interference layer is flush with the outer surface of the imaging detector in the circumferential direction.

[0006] As a further improvement of this utility model, the anti-interference layer is black.

[0007] As a further improvement of this utility model, the anti-interference layer is a reflective layer; or, the anti-interference layer is a light-absorbing layer.

[0008] As a further improvement of this utility model, the thickness of the anti-interference layer is 20μm to 60μm.

[0009] As a further improvement of the present invention, the object side of the optical lens group has an aperture stop, and the anti-interference layer is also formed on the object side of the optical lens group in the area other than the aperture stop.

[0010] As a further improvement of the present invention, the metasurface lens has an object-side surface facing the object side and an image-side surface facing the image side, and the image-side surface of the metasurface lens has a subwavelength micro / nano structure.

[0011] As a further improvement of the present invention, the optical lens group includes at least two metasurface lenses arranged sequentially from the object side to the image side, and the metasurface lenses have an object side facing the object side and an image side facing the image side.

[0012] The optical lens group also includes a filter structure disposed on the object side or image side of any metasurface lens.

[0013] As a further improvement of the present invention, an adhesive layer is provided between the optical lens group and the imaging detector; and / or, an anodic bonding layer is provided between adjacent optical elements in the optical lens group.

[0014] To achieve the above objectives, this utility model also provides an eye-tracking device, including the aforementioned optical imaging lens, which is used to acquire corneal images of the eye to be tracked.

[0015] The beneficial effects of this utility model are as follows: The optical imaging lens of this utility model, by using a metasurface lens instead of the existing curved surface structure lens, can avoid the limitations of the curved surface and volume of traditional lenses, and can reduce the volume of the optical imaging lens. At the same time, by forming an anti-interference layer directly on the outer peripheral surface of the optical lens group, instead of the lens barrel or light shield in the prior art, the overall volume of the optical imaging lens will not be increased, which is conducive to the miniaturization design of the optical imaging lens and expands the application scenarios of the optical imaging lens, such as its application in eye tracking devices. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an optical imaging lens in a specific embodiment of the present invention;

[0017] Figure 2 Figure 1 A schematic diagram of the optical imaging lens after the anti-interference layer has been removed;

[0018] Figure 3 yes Figure 1 A schematic diagram of the optical system in a specific embodiment corresponding to the optical imaging lens shown;

[0019] Figure 4 yes Figure 3 The diagram shows the light spot pattern of the optical system shown.

[0020] Figure 5 yes Figure 3 The field curvature and distortion diagrams of the optical system shown are as follows: Figure 5 The left image in the diagram is the field curvature diagram, and the right image is the distortion diagram;

[0021] Figure 6 yes Figure 3 The MTF curve of the optical system shown;

[0022] Figure 7 yes Figure 3 The phase profile diagrams of the first metasurface lens and the second metasurface lens in the optical system shown are shown, with the left figure being the phase profile diagram of the first metasurface lens and the right figure being the phase profile diagram of the second metasurface lens.

[0023] Figure 8 It is molding Figure 3 The structure of a circular metasurface nanopillar in the metasurface lens of the optical system shown;

[0024] Figure 9 The image shown is a result of phase and transmittance scanning of the designed metasurface using the simulation software FDTD.

[0025] Figure 10 To combine the phase database obtained from the scan with Figure 7 A schematic diagram of the micro / nano structure on the metasurface lens obtained by fitting the phase data in the image;

[0026] Figure 11 It is Figure 10 The simulation diagram obtained after importing the metasurface lens model into physical simulation software;

[0027] Figure 12 It is Figure 10 The specific focusing efficiency data was obtained after importing the metasurface lens model into physical simulation software for simulation. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. Please refer to the accompanying drawings for further details. Figures 1 to 12 The illustrations shown represent preferred embodiments of the present invention. However, it should be noted that these embodiments are not intended to limit the present invention, and any functional or structural equivalent modifications or substitutions made by those skilled in the art based on these embodiments are within the protection scope of the present invention.

[0029] It should be understood that terms such as “including” as used herein do not exclude the presence or addition of one or more other components or combinations thereof.

[0030] Please refer to Figures 1-2 As shown, this utility model provides an optical imaging lens and an eye-tracking device (not shown) incorporating the optical imaging lens. The optical imaging lens is used to acquire an image of the object to be photographed. When the optical imaging lens is applied to an eye-tracking device, it acquires an image of the eyeball / cornea to be tracked. Subsequently, the user's gaze direction and / or gaze point can be obtained based on the eyeball / cornea image, enabling human-computer interaction. For example, the content displayed to the user can be adjusted in a timely manner based on the user's gaze direction and / or gaze point.

[0031] Specifically, the eye-tracking device includes a support carrier, at least two light source points disposed on the support carrier, the aforementioned optical imaging lens disposed on the support carrier, and an image processing module equipped with image processing software. The image processing module is communicatively connected to the optical imaging lens to acquire images captured by the optical imaging lens.

[0032] In some optional embodiments, the support carrier is a head-mounted device, such as glasses. In this case, the light source and the optical imaging lens are both installed at a preset position on the glasses.

[0033] The eye-tracking device described in this invention, except for the optical imaging lens, can use corresponding components from the prior art, and will not be described in detail here.

[0034] An optical imaging lens includes an optical lens group and an imaging detector. The optical lens group includes an object-side surface facing the object and an image-side surface facing the image. The imaging detector is connected to the image-side surface of the optical lens group. The reflected light from the object to be photographed is modulated by the optical lens group and then forms an image in a preset area of ​​the imaging detector.

[0035] The aforementioned optical modulation includes, but is not limited to, image quality control, phase and amplitude modulation, and focusing functions.

[0036] The optical lens group also includes an outer peripheral surface located between the object-side surface and the image-side surface of the optical lens group. The object-side surface, the image-side surface, and the outer peripheral surface of the optical lens group together form the outer surface of the optical lens group.

[0037] In this embodiment, all optical lenses in the optical lens group are metasurface lenses. On the one hand, metasurface lenses can achieve complex optical modulation functions with extremely thin thickness, and since all metasurface lenses are planar structures, all optical lenses can be seamlessly stacked together. In addition, the high integration of metasurface lenses allows multiple optical functions to be integrated into a single planar device, thereby significantly reducing the size and weight of the optical imaging lens, which is beneficial for the miniaturization design of the optical imaging lens. On the other hand, metasurface lenses can be fabricated using existing mature semiconductor fabrication processes, which are relatively mature, thereby improving the performance stability of the optical imaging lens.

[0038] In some optional embodiments, the optical lens group includes at least two metasurface lenses arranged sequentially from the object side to the image side. Each metasurface lens has an object-side surface facing the object side and an image-side surface facing the image side. The image-side surface of the metasurface lens has a subwavelength micro / nano structure. That is, the metasurface pattern is formed only on the image-side surface of the metasurface lens.

[0039] Combination Figure 1 As shown in a specific embodiment of this utility model, the optical lens group includes two metasurface lenses arranged sequentially from the object side to the image side, namely a first metasurface lens and a second metasurface lens. The first metasurface lens is configured to adjust image quality and perform partial focusing, while the second metasurface lens is configured to perform focusing. Specifically, the first metasurface lens includes a first object-side surface S1 facing the object side and a first image-side surface S2 facing the image side. The second metasurface lens includes a second object-side surface S3 facing the object side and a second image-side surface S4 facing the image side. Micro-nano structures are disposed on the first image-side surface S2 and the second image-side surface S3. Of course, this is not a limitation; in other embodiments, the optical lens group may also include three or more metasurface lenses.

[0040] Specifically, the image-side surface of a metasurface lens, apart from the area where micro-nano structures are set, can be shielded by overlaying black resin or plating with chrome.

[0041] The optical imaging lens also includes an anti-interference layer formed on its outer peripheral surface. This anti-interference layer isolates ambient light and reduces interference from stray ambient light on the imaging process. In this invention, an anti-interference layer directly formed on the outer peripheral surface of the optical lens group replaces the lens barrel or light shield used in the prior art. This does not increase the overall size of the optical imaging lens, which is beneficial for miniaturization and expands its application scenarios, such as its use in eye-tracking devices.

[0042] In some optional embodiments, the anti-interference layer is black in color to absorb ambient stray light.

[0043] In some optional embodiments, the anti-interference layer is a light-absorbing layer, such as a black ink layer or a black resin layer with light-absorbing properties. In this case, the light-absorbing layer can be formed by coating or inkjet printing on the outer peripheral surface of the optical lens assembly.

[0044] In some optional embodiments, the anti-interference layer is a reflective layer, such as a chromium-containing reflective coating. In this case, the reflective layer can be formed by coating the outer peripheral surface of the optical lens assembly.

[0045] It is understood that the light-absorbing layer mentioned above is not limited to the anti-interference layer having only a light-absorbing function; it can have a light-absorbing function as well as a reflective function. Similarly, the reflective layer mentioned above is not limited to the anti-interference layer having only a reflective function; it can have a reflective function as well as a light-absorbing function, in order to reduce the interference of ambient stray light on imaging.

[0046] In some optional implementations, combined with Figure 2 As shown, the circumferential dimension of the outer peripheral surface of the optical lens group is smaller than the circumferential dimension of the imaging detector in the corresponding circumferential direction. Combined with... Figure 1 As shown, the outer surface of the anti-interference layer in the circumferential direction is flush with the outer surface of the imaging detector in the corresponding circumferential direction. In this embodiment, by setting the circumferential dimension of the optical lens group to be smaller than that of the imaging detector in the circumferential direction, space can be reserved for the anti-interference layer, so that after the anti-interference layer is formed, the outer surface of the anti-interference layer in the circumferential direction is flush with the outer surface of the imaging detector in the corresponding circumferential direction, thereby improving the overall appearance of the optical imaging lens.

[0047] Preferably, the thickness of the anti-interference layer is 20μm to 60μm. In one specific embodiment, the thickness of the anti-interference layer is 50μm. It is understood that the difference between the circumferential dimension of the optical lens group and the circumferential dimension of the imaging detector is the thickness of the anti-interference layer; the two are corresponding.

[0048] Specifically, the object-side surface of the optical lens group has an aperture stop, and the anti-interference layer is also formed on the object-side surface of the optical lens group in areas other than the aperture stop. That is, after assembling the optical lens group with the imaging detector, the anti-interference layer is formed simultaneously on the object-side surface and the outer peripheral surface of the optical lens group. Furthermore, the anti-interference layer is formed only in a portion of the object-side surface of the optical lens group, leaving the area without the anti-interference layer on the object-side surface of the optical lens group and forming the aperture stop of the entire optical imaging lens. This simplifies the fabrication of the optical imaging lens.

[0049] In a specific embodiment shown in the figure, the object side of the aforementioned optical lens group refers to the first object side S1 of the first metasurface lens.

[0050] In some optional embodiments, the optical lens group further includes a filter structure disposed on the object-side or image-side of any metasurface lens. This filter structure allows only 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 sensitivity and capturing ability of the optical imaging lens to light, and ensuring image quality.

[0051] Specifically, the filter structure can be a narrowband bandpass filter or a narrowband bandpass filter film.

[0052] In one specific embodiment, the filtering structure is a narrow-band bandpass filter disposed on the image-side side of the metasurface lens near the imaging detector. However, this is not a limitation.

[0053] In such Figure 1 In one specific embodiment shown, the image-side surface of the metasurface lens near the imaging detector refers to the second image-side surface S4 of the second metasurface structure.

[0054] The optical imaging lens of this utility model will be further described below in conjunction with the design and manufacturing process.

[0055] Step 1: Optimize the all-planar optical path structure using optical design software.

[0056] S11: Determine the optical path architecture. In this embodiment, a metasurface lens is used to construct the optical path, and the optical elements include only planar metasurface lenses and filter structures.

[0057] S12: Determine the initial parameters of the optical system of the optical imaging lens based on its requirements. These requirements include operating wavelength, field of view, focal length, and resolution. Initial parameters include, but are not limited to, the number, thickness, and material of metasurfaces. In the case of an eye-tracking device, the aforementioned requirements for the optical imaging lens are also the requirements for the eye-tracking system.

[0058] S13: Ray Tracing and Wavefront Optimization. A planar optical system model is built in optical simulation software (Zemax or Code V). A metasurface (or phase surface) is used to replace the traditional refractive lens to simulate the metasurface lens's control effect on light waves. The ray tracing function of the optical software is used to analyze and optimize the optical path parameters. Optimization objectives include: beam collimation / focusing for infrared illumination and imaging; aberration correction to eliminate spherical aberration, coma, etc., and improve image quality; and field of view expansion to ensure clarity for large-angle eye tracking. The metasurface lens parameters are adjusted through the software's optimization algorithm to ensure the entire optical system meets the requirements of the optical modulation transfer function (MTF) and spot diagram.

[0059] Step 2: Metasurface phase design and nanostructure realization.

[0060] S21: Extract the target phase distribution from the optimized optical system. The phase is defined by the surface shape formula.

[0061] S22: Design of nano-structure units (Meta-atom).

[0062] S221: High refractive index materials are selected as metasurface substrates to improve phase modulation efficiency. Metasurface substrates include, but are not limited to, silicon nitride substrates and titanium dioxide substrates.

[0063] S222: Design 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. The operating wavelength is in the visible, infrared, or ultraviolet bands, such as near-infrared 850nm / 940nm. The phase delay is 0–2π.

[0064] S223: The scattering characteristics of a single nanostructure are optimized by simulating the Finite-Difference Time-Domain (FDTD) method or Rigorous Coupled Wave Analysis (RCWA) to ensure the accuracy of phase modulation.

[0065] S23: Metasurface Array Arrangement. Based on the phase distribution, nanostructures of different sizes / shapes are arranged in a gradient pattern to form a complete metasurface lens. Structural parameters are optimized to ensure practical fabrication feasibility, taking into account manufacturing process constraints such as photolithography precision and etching depth. The metasurface lens can be fabricated using traditional semiconductor processes.

[0066] S24: System Integration and Testing. Integrate metasurface lenses with CMOS sensors, light sources, and other components to construct a complete eye-tracking device. Verify the system's performance meets design requirements through experimental testing (such as MTF measurement and eye-tracking accuracy evaluation).

[0067] Step 3: Optical imaging lens packaging process.

[0068] S31: First, the optical imaging lens is structurally designed: Based on the optical path design, metasurface lens, imaging detector, etc., the optical imaging lens is structurally designed to minimize its size. In this embodiment, the optical imaging lens is configured to include, from the object side to the image side, the following components arranged sequentially: a first metasurface lens, a second metasurface lens, a narrow-band bandpass filter, and an imaging detector. Specifically, the object side of the first metasurface lens forms an aperture, and the effective area of ​​the image side of the first metasurface lens has a micro / nano structure, while the ineffective area is shielded using black glue or chrome plating; the effective area of ​​the image side of the second metasurface lens also has a micro / nano structure, and the ineffective area is shielded using black glue or chrome plating; the image side and object side of the narrow-band bandpass filter are shielded using black glue or chrome plating according to the optical path.

[0069] S32: Connection between optical elements of the optical lens group: Adjacent optical elements are anodicly bonded using pre-processed bonding alignment marks, thus forming an anodic bonding layer between adjacent optical elements. In this embodiment, specifically, the first metasurface lens and the second metasurface lens, and the second metasurface lens and the narrowband bandpass filter are anodicly bonded using pre-processed bonding alignment marks, to bond the first metasurface lens, the second metasurface lens, and the narrowband bandpass filter together.

[0070] S33: The optical lens group is bonded to the imaging detector using an active alignment process to complete the module packaging; specifically, there is an adhesive layer between the optical lens group and the imaging detector.

[0071] S34: Outer wall light shielding, using coating or inkjet printing to create a pre-defined anti-interference layer on the outer peripheral surface of the optical lens group. This anti-interference layer is also formed on the object side of the optical lens group, except for the aperture hole, to avoid interference from ambient stray light without increasing the overall size of the optical imaging lens.

[0072] Specifically, in step S34, the anti-interference layer can be a black ink layer with light-absorbing properties, a black resin layer with light-absorbing properties, or a chromium-containing reflective coating with light-reflecting properties. The thickness of the anti-interference layer is 20 μm to 60 μm.

[0073] Combination Figure 3The diagram shown is a schematic representation of the optical system structure according to a specific embodiment of this utility model. The light source is incident from the first object-side surface S1 of the first metasurface lens. Light source types include, but are not limited to, LEDs, EELs, VCSELs, fiber lasers, and natural light; this embodiment selects an LED light source. The optical system in this specific embodiment will be further described below in conjunction with the design and manufacturing process.

[0074] Specifically, in the optical design section, the basic parameters are first defined. Figure 3 The optical system in the specific embodiment shown operates in the near-infrared band of 940 + / - 20 nm to match the iris reflection characteristics for eye tracking. It has a field of view (FOV) of 120° to cover the human eye's range, a minimum focal length to meet the requirements of miniaturized modules, and an MTF greater than 0.3 at one-quarter of the Nyquist frequency. The imaging detector uses a 400*400*2.2µm OG0TC1B chip with an F-number of 2.4, and the total system length is 1.28mm. To achieve the most compact module size possible, all optical elements in this invention are planar structures, avoiding the limitations of curved surfaces and volume inherent in traditional lenses. Figure 3 As shown, the entire optical system, from left to right, consists of a first metasurface lens, a second metasurface lens, a narrowband bandpass filter, and an imaging detector, which includes a detector protective glass. Detailed parameters of the optical system are shown in Table 1 below, where S1 is the first object-side surface of the first metasurface lens, S2 is the first image-side surface of the first metasurface lens, S3 is the second object-side surface of the second metasurface lens, and S4 is the second image-side surface of the second metasurface lens. S2 and S4 have micro / nano structures. S5 is the object-side surface of the narrowband bandpass filter, S6 is the image-side surface of the narrowband bandpass filter, and S7 is the detector protective glass. All these structures are planar and can be bonded together with adhesive or anodic bonding to form a lens-less structure, making the system more concise and compact.

[0075] Table 1

[0076] Face number Surface type radius of curvature thickness Material OBJ spherical endless 23.000 S1 spherical endless 0.400 1.47,65.34 S2 metasurface endless 0.000 S3 spherical endless 0.400 1.47,65.34 S4 metasurface endless 0.000 SS spherical endless 0.210 1.52，52.53 S6 spherical endless 0.060 S7 spherical endless 0.150 1.52，52.53 S8 spherical endless 0.040

[0077] Figure 4-6 Showing Figure 3 The optical performance of the optical system shown, wherein, Figure 4 A series of light spot diagrams, Figure 5 For field curvature diagrams and distortion diagrams, Figure 6 This is the MTF curve. (From...) Figure 4 As can be seen, the all-planar optical module based on metasurface lenses, under LED illumination, produces a focused light spot that is essentially close to the diffraction limit. Figure 4 The black circle in the image has good focusing ability. (By...) Figure 5As can be seen, the distortion is relatively large, around -30%, which is mainly due to the excessive field of view. However, the distortion will not affect the image sharpness, but will only cause image deformation, which can be corrected and compensated by subsequent algorithms. Figure 6 The MTF curve in the figure is used to describe the system's resolution, by Figure 6 It can be seen that for the OG0TC1B chip, the Nyquist frequency Ny = 1 / (2*2.2) = 227 lp / mm. It can be seen that at 56.8 lp / mm (1 / 4 Ny), the minimum MTF value is greater than 0.4, and at 113.6 lp / mm (1 / 2 Ny), the minimum MTF value is greater than 0.12, which can meet the resolution requirements.

[0078] In this embodiment, a phase surface is used as an equivalent replacement for a metasurface to constrain... By controlling the ratio between the maximum phase difference and the effective optical radius of the metasurface lens, the 2π phase period borne by the metasurface lens per unit length is made to match the phase of the micro / nano structure to the target phase, thus more fully utilizing the optical performance of the metasurface. The specific phase profiles of the two metasurfaces are shown in... Figure 7 ,in, Figure 7 The left image in the diagram is the phase profile of the first metasurface lens, and the right image is the phase profile of the second metasurface lens.

[0079] After completing the optical design, the next step is the metasurface phase design and nanostructure realization. Metasurface nanopillars are subwavelength in size, and their basic shapes can be extended from circular, circular, square, and square-holed to free geometric forms. Among these, circular structures are commonly used due to their polarization independence and ease of fabrication. This embodiment also selects circular nanopillars as the basic shape, such as... Figure 8 The diagram shows a basic metasurface nanopillar structure. The substrate material for the nanopillars includes, but is not limited to, glass substrates and silicon substrates; in this embodiment, BF33 glass is chosen as the metasurface substrate. The protective filling material between the structures can be air, adhesive, SiO2, Si3N4, etc.; in this embodiment, adhesive is chosen as the protective layer, and the adhesive has a refractive index of 1.59.

[0080] Then, phase and transmittance scans were performed using the simulation software FDTD. The height of the nanopillars was fixed at 660 nm, while the radius was used as a variable, scanning from 40 nm to 150 nm. The final scan results are shown in the figure below. Figure 9 As shown, the transmittance curve exhibits two distinct decreasing peaks. These are resonance peaks caused by the coupling mismatch between the refractive index of the nanopillars and the ambient refractive index. In actual screening, these two peaks are excluded to improve transmittance. Then, the obtained phase database is compared with... Figure 7The zemax phase data is fitted, and the fitting process can be simply described as follows: 1. Zemax optimization is used to obtain the phase profile; 2. The radius-phase curve obtained from the scan is referenced. Figure 9 This allows us to obtain the radius of the nanopillars corresponding to the phase at each position, arranged in concentric rings, such as... Figure 10 As shown, this is the micro / nano structure on the final metasurface lens.

[0081] The metasurface lens model with the fitted micro / nano structure obtained above was imported into physical simulation software for simulation, and the results are as follows: Figure 11 As shown, when the incident light angle varies from 0 to 50°, the focused spot position is on the same plane, and the morphology is basically a stable circle, which proves the precise phase control capability of the metasurface designed in this embodiment. Specific focusing efficiency data are as follows: Figure 12 As shown, the calculation formula is the energy integral of the focal 8µm region divided by the incident light energy integral. Figure 12 As can be seen, the focusing efficiency decreases as the incident angle increases, from 82% to 66%, but it still remains at a relatively high level.

[0082] Compared with existing technologies, the optical imaging lens of this invention, by using a metasurface lens instead of the existing curved lens structure, avoids the limitations of the curved surface and volume of traditional lenses, thus reducing the size of the optical imaging lens. Furthermore, by forming an anti-interference layer directly on the outer peripheral surface of the optical lens group, replacing the lens barrel or light shield of existing technologies, the overall size of the optical imaging lens is not increased, which is beneficial for the miniaturization design of the optical imaging lens and expands its application scenarios, such as its application in eye-tracking devices. Based on the metasurface, the focal length of the optical imaging lens can be reduced, and a lens barrel-less assembly structure can be achieved. The final size can be (1.6~2.2)*(1.6~2.2)*(1.5~1.8)mm, such as 2*2*1.6mm, significantly reducing the size of the optical imaging lens.

[0083] 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.

[0084] 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 an optical lens group and an imaging detector, wherein the optical lens group includes an object-side surface facing the object side, an image-side surface facing the image side, and an outer peripheral surface located between the object-side surface and the image-side surface of the optical lens group, and the imaging detector is connected to the image-side surface of the optical lens group; characterized in that: All optical lenses in the optical lens group are metasurface lenses; the optical imaging lens also includes an anti-interference layer formed on the outer peripheral surface, which is used to isolate ambient light.

2. The optical imaging lens as described in claim 1, characterized in that: The circumferential dimension of the outer peripheral surface of the optical lens group is smaller than that of the imaging detector in the circumferential direction; the anti-interference layer is flush with the outer surface of the imaging detector in the circumferential direction.

3. The optical imaging lens as described in claim 1, characterized in that: The anti-interference layer is black.

4. The optical imaging lens as described in claim 1, characterized in that: The anti-interference layer is a reflective layer; or, the anti-interference layer is a light-absorbing layer.

5. The optical imaging lens as described in claim 1, characterized in that: The thickness of the anti-interference layer is 20μm to 60μm.

6. The optical imaging lens as described in claim 1, characterized in that: The object-side surface of the optical lens group has an aperture stop, and the anti-interference layer is also formed on the object-side surface of the optical lens group in areas other than the aperture stop.

7. The optical imaging lens as described in claim 1, characterized in that: The metasurface lens has an object-side surface facing the object side and an image-side surface facing the image side, and the image-side surface of the metasurface lens has a subwavelength micro / nano structure.

8. The optical imaging lens as described in claim 1, characterized in that: The optical lens group includes at least two metasurface lenses arranged sequentially from the object side to the image side, and the metasurface lenses have an object side facing the object side and an image side facing the image side. The optical lens group also includes a filter structure disposed on the object side or image side of any metasurface lens.

9. The optical imaging lens as described in claim 1, characterized in that: An adhesive layer is provided between the optical lens group and the imaging detector; and / or, an anodic bonding layer is provided between adjacent optical elements in the optical lens group.

10. An eye-tracking device, characterized in that: The eye-tracking device includes an optical imaging lens as described in any one of claims 1 to 9, the optical imaging lens being used to acquire a corneal image of the eye to be tracked.

Images