Large-view-field optical lens, eye movement tracking system and terminal equipment

Abstract

The invention relates to a large-view-field optical lens, an eye movement tracking system and terminal equipment, and belongs to the field of optical lenses, the large-view-field optical lens comprises a first lens, a second lens and an optical filter which are sequentially arranged from an object plane to an image plane along an optical axis, the first lens and the second lens are metasurface lenses, and the metasurface lenses are provided with micro-nano structures. According to the optical lens, the two super lenses are adopted, the size is small, cost is saved, and meanwhile the working temperature range is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of optical lenses, and in particular relates to a large-field optical lens, an eye tracking system, and a terminal device. Background Art

[0002] Eye tracking is a sensor technology that uses the detection and analysis of eye movements to understand human visual behavior and attention distribution. The core of eye tracking is to capture eye movements with optical sensors and use algorithms to calculate the location of the gaze point. Common eye tracking technologies involve eye tracking devices capturing eye images with high-speed cameras and using advanced image processing algorithms to identify the pupil center and corneal reflection point. This data is further processed to calculate the three-dimensional gaze point location.

[0003] Eye tracking technology has a wide range of applications, covering scientific research, medical care, human-computer interaction, virtual reality and other aspects. For example, it is used in fields such as psychology and cognitive science to study human attention, decision-making processes and visual behavior; it can also be applied to web pages and mobile applications for human-computer interaction to optimize user experience and interface design; integrating it into XR headsets can achieve natural interaction methods, such as gaze point rendering and virtual keyboard operations.

[0004] The main components of an eye tracking system include a light source, lens system, sensor, and data processing algorithms. The lens system is responsible for focusing and imaging, ensuring the camera can obtain a clear image of the eye. It is a critical component for accurate eye tracking, and its design and optimization directly impact the accuracy of eye movement data and system performance.

[0005] Traditional eye-tracking lens systems typically require a large space to accommodate the lens assembly and other optical components, making eye-tracking devices large and heavy. Due to size and weight limitations, traditional lens systems face significant challenges when integrating with miniaturized devices such as wearables and mobile terminals. This limits the widespread application of eye-tracking technology in a wider range of fields, such as smart glasses and mobile medical devices. Furthermore, traditional eye-tracking lenses have a narrow field of view, meaning the range of eye movements that can be monitored is relatively small. Users must maintain their eyes within a specific range to obtain clear and accurate images. Once the eyes move outside this range, image quality degrades significantly, and even image distortion and color errors may occur, affecting the continuity and stability of eye tracking. Furthermore, traditional lenses suffer from low light efficiency and cannot meet the requirements of high-brightness scenes, affecting eye tracking accuracy and user experience. There is also room for improvement in their imaging resolution. Summary of the Invention

[0006] The present application provides a large-field-of-view optical lens, an eye tracking system, and a terminal device to at least solve the above technical problems existing in the prior art.

[0007] A first aspect of an embodiment of the present application provides a large field of view optical lens, comprising a first lens, a second lens, and a filter arranged in sequence along an optical axis from an object plane to an image plane, wherein the first lens and the second lens are both metasurface lenses, and a micro-nano structure is provided on the metasurface lens;

[0008] The wide field of view optical lens meets the following requirements:

[0009]

[0010] Among them, M is the thickness of the first lens substrate, D1 is the effective area size of the first lens micro-nano structure side, D2 is the effective area size of the second lens micro-nano structure side, and BFL is the back focus distance, that is, the distance from the image side of the filter to the imaging surface.

[0011] In one possible implementation manner, the side of the metasurface lens provided with the micro-nano structure faces the object plane / image plane.

[0012] In one embodiment, the sides of the first lens and the second lens provided with the micro-nano structure both face the object plane.

[0013] In one embodiment, the sides of the first lens and the second lens provided with the micro-nano structure both face the image plane.

[0014] In one possible implementation manner, a distance TTL from the optical axis center of the object side of the first lens to the image plane satisfies: TTL≤1.40 mm.

[0015] In one possible implementation manner, the relative illumination of the large-field optical lens satisfies RI ≥ 60%; the field of view angle satisfies: Fov ≥ 120°; and the operating temperature is -45°C to 105°C.

[0016] In one embodiment, a stop is further included.

[0017] In one embodiment, the aperture is disposed between the first lens and the second lens.

[0018] A second aspect of an embodiment of the present application provides an eye tracking system, comprising any of the above-mentioned large-field-of-view optical lenses.

[0019] A third aspect of an embodiment of the present application provides a terminal device, comprising the above-mentioned eye tracking system.

[0020] Compared with the prior art, this application has the following advantages:

[0021] The large field of view optical lens of this application adopts a two-piece metalens design, which achieves small size and cost savings while ensuring an operating temperature range. In addition, by rationally distributing the phase of the metasurface, the eye-tracking metasurface lens meets the object distance TTL ≤ 1.40mm, and the eye-tracking metasurface lens has a high resolution of 114lp / mm and MTF > 0.2; at the same time, the relative illumination meets RI ≥ 60%, and the imaging field of view meets FOV ≥ 120°, solving the problems of large size, high cost, low relative illumination, small imaging range, and low resolution in existing eye-tracking technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a large field of view optical lens in an embodiment of the present application;

[0023] Figure 2 Schematic diagram of the MTF of the wide field of view optical lens in Example 1 of the present application;

[0024] Figure 3 Schematic diagram of the diffuse spot of the large field of view optical lens in Example 1 of the present application;

[0025] Figure 4 Schematic diagram of relative illumination of the wide field of view optical lens in Example 1 of the present application;

[0026] Figure 5 Schematic diagram of the MTF of the wide field of view optical lens in Example 2 of the present application;

[0027] Figure 6 Schematic diagram of the diffuse spot of the large field of view optical lens in Example 2 of the present application;

[0028] Figure 7 Schematic diagram of relative illumination of a wide-field optical lens in Example 2 of the present application;

[0029] Description of reference numerals:

[0030] 110, first lens; 120, aperture; 130, second lens; 140, filter; 150, imaging surface. DETAILED DESCRIPTION

[0031] The present invention will be described in further detail below with reference to the accompanying drawings.

[0032] In the description of this application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application.

[0033] Metasurface technology is an artificial layered material composed of a two-dimensional periodic array of subwavelength structures. By designing and manufacturing nanostructures with subwavelength dimensions, it is possible to flexibly control the amplitude, polarization state, phase, polarization mode, propagation mode and other characteristics of electromagnetic waves. Metasurface technology can realize ultra-thin planar optical components that are smaller and lighter than traditional optical components while maintaining high efficiency. In addition, metasurface technology is compatible with existing semiconductor manufacturing processes, facilitating large-scale production and integration into various optical and electronic devices. Metasurface technology has broad application prospects in optical imaging, optical communications, polarization optics and other fields. In recent years, metasurface technology has demonstrated great potential in many fields, especially in devices such as light-emitting diodes, lasers, optical modulators and photodetectors, and may bring revolutionary breakthroughs.

[0034] Eye tracking systems made using metasurfaces can effectively solve the problems existing in traditional eye tracking lenses. Metalens systems can usually realize ultra-thin optical components and achieve the required optical performance in a relatively small optical system, which helps to reduce the volume and weight of the optical system. In addition, their imaging resolution and relative illumination are relatively high, which can achieve high-quality imaging. Their imaging range is also relatively large, which can better monitor human eye movements, while having a low manufacturing cost.

[0035] An embodiment of the present invention discloses a wide-field optical lens comprising a first lens, a second lens, and a filter, arranged in sequence along the optical axis from the object plane to the image plane. The first lens and the second lens are both metasurface lenses, and each metasurface lens includes a substrate and a micro-nanostructure disposed on the substrate. This wide-field optical lens satisfies the following requirements:

[0036]

[0037] Among them, M is the thickness of the first lens substrate of the eye-tracking metasurface lens, D1 is the effective area size of the first lens on the micro-nanostructure side, D2 is the effective area size of the second lens on the micro-nanostructure side, and BFL is the back focus distance, that is, the distance from the image side of the filter to the imaging surface.

[0038] The substrate materials of the metasurface lens include, but are not limited to, amorphous silicon, crystalline silicon, borosilicate, silicon dioxide, quartz, and glass. The micro-nanostructure materials of the metasurface lens include, but are not limited to, amorphous silicon, crystalline silicon, silicon dioxide, silicon nitride, and titanium dioxide.

[0039] In a preferred embodiment, the visible light lens further includes an aperture, which is disposed between the first lens and the second lens.

[0040] Specifically, Figure 1 The embodiment of the present invention provides a large field of view and high resolution eye tracking lens. Figure 1 The wide-field optical lens includes a first lens 110, an aperture 120, a second lens 130, and a filter 140, arranged in sequence along the optical axis from the object plane to the image plane. The first lens 110 and the second lens 130 are both metasurface lenses, each provided with a micro-nanostructure. The side of the metasurface lens provided with the micro-nanostructure can face either the object plane or the image plane. It is understood that the configuration of the first lens 110 and the second lens 130 includes, but is not limited to, the following methods.

[0041] First, the sides of the first lens 110 and the second lens 130 provided with the micro-nano structures both face the object plane.

[0042] Secondly, the sides of the first lens 110 and the second lens 130 where the micro-nano structures are provided are both facing the image plane.

[0043] Third, the side of the first lens 110 provided with the micro-nano structure faces the object plane, and the side of the second lens 130 provided with the micro-nano structure faces the image plane.

[0044] Fourthly, the side of the first lens 110 provided with the micro-nano structure faces the image plane, and the side of the second lens 130 provided with the micro-nano structure faces the object plane.

[0045] The large-field-of-view optical lens in the embodiment of the present invention is small in size and has a high resolution of 114lp / mm and an MTF greater than 0.2. At the same time, the relative illumination satisfies RI ≥ 60%, the imaging field of view satisfies FOV ≥ 120°, and the operating temperature is -45°C to 105°C. At the same time, the metasurface lens can effectively correct aberrations and provide high-quality imaging effects.

[0046] like Figure 1 As shown, the incident light enters through the object side surface of the first lens 110 , passes through the aperture 120 , and then passes through the second lens 130 and the filter 140 , and finally converges on the imaging surface 150 .

[0047] Example 1

[0048] For example, Table 1 describes in detail the specific optical data parameters of each lens in the large field of view optical lens provided by the embodiment of the present invention in a feasible implementation manner. The optical data parameters in Table 1 correspond to Figure 1 The wide field of view optical lens shown.

[0049] The first lens 110 and the second lens 130 are both metasurface lenses; the aperture 120 is located on the first surface of the second lens 130 .

[0050] Table 1

[0051] Surface number Face shape Curvature radius (mm) Spacing (mm) Material 1 Binary2 Infinity 0.30 Glass 2 Standard Infinity 0.00 3STOP Standard Infinity 0.00 4 Standard Infinity 0.50 Glass 5 Binary2 Infinity 0.00 6 Standard Infinity 0.36 Glass 7 Standard Infinity 0.18 8IMAGE Standard Infinity -

[0052] The surface numbers are numbered according to the order of the surfaces of each lens. For example, surface number 1 represents the object side surface of the first lens 110, surface number 2 represents the image side surface of the first lens 110, and so on. The radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface is curved toward the image side, and a negative value represents that the surface is curved toward the object side. "Infinity" represents that the surface is flat. The spacing represents the axial distance from the center of the current surface to the next surface. The units of the radius of curvature and the spacing are both millimeters (mm).

[0053] Exemplarily, Table 2 details the phase of the metasurface in this embodiment in a feasible implementation manner.

[0054] Table 2

[0055] Surface number R1 A1 A2 A3 A4 A5 1 1 5.53E+003 2.76E+002 1.97E+004 8.08E+005 4.74E+006 5 1 5.06E+003 4.54E+001 6.06E+003 3.54E+001 4.06E+003

[0056] Where R1 is the normalized radius of the binary surface.

[0057] In this embodiment, the thickness of the first lens substrate, the effective area size of the first lens micro-nano structure side, the effective area size of the second lens micro-nano structure side, and the back focus distance meet the following conditions: The total optical length satisfies TTL=1.34mm; the field of view angle satisfies Fov=120°;

[0058] Figure 2 This is a schematic diagram of the MTF of the wide-field optical lens provided in an embodiment of the present invention. The wide-field optical lens provided in this embodiment has an operating band of 940±17.5nm, an Fno of 2.0, a high resolution of 114lp / mm, and an MTF>0.2, which meets the requirements of eye tracking technology.

[0059] Figure 3 Schematic diagram of the diffuse spot of the large-field-of-view optical lens provided by an embodiment of the present invention. The large-field-of-view optical lens provided by an embodiment of the present invention has a relatively concentrated and evenly distributed diffuse pattern over the entire long-wave band, which can meet the requirements of high-resolution imaging.

[0060] Figure 4 A schematic diagram of relative illumination of a large field of view optical lens according to an embodiment of the present invention is provided, which shows relative illumination values corresponding to different fields of view, such as Figure 4 As shown, the wide-field optical lens provided by the embodiment of the present invention has a relative illumination greater than 64% in the entire field of view in the working band, and the brightness is uniform.

[0061] Example 2

[0062] For example, Table 3 describes in detail the specific optical data parameters of each lens in the large field of view optical lens provided by the embodiment of the present invention in a feasible implementation manner. The optical data parameters in Table 3 correspond to Figure 1 The wide field of view optical lens shown.

[0063] The first lens 110 and the second lens 130 are both metasurface lenses; the aperture 120 is located on the first surface of the second lens 130 .

[0064] Table 3

[0065] Surface number Face shape Curvature radius (mm) Spacing (mm) Material 1 Binary2 Infinity 0.40 Glass 2 Standard Infinity 0.00 3STOP Standard Infinity 0.00 4 Standard Infinity 0.40 Glass 5 Binary2 Infinity 0.00 6 Standard Infinity 0.36 Glass 7 Standard Infinity 0.18 8IMAGE Standard Infinity -

[0066] The surface numbers are numbered according to the order of the surfaces of each lens. For example, surface number 1 represents the object side surface of the first lens 110, surface number 2 represents the image side surface of the first lens 110, and so on. The radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface is curved toward the image side, and a negative value represents that the surface is curved toward the object side. "Infinity" represents that the surface is flat. The spacing represents the axial distance from the center of the current surface to the next surface. The units of the radius of curvature and the spacing are both millimeters (mm).

[0067] Exemplarily, Table 4 details the phase of the metasurface in this embodiment in a feasible implementation manner.

[0068] Table 4

[0069] Surface number R1 A1 A2 A3 A4 A5 1 1 5.35E+003 6.02E+003 1.55E+002 3.37E+003 9.80E+003 5 1 5.11E+003 4.82E+001 2.28E+002 4.27E+002 1.39E+003

[0070] Where R1 is the normalized radius of the binary surface.

[0071] In this embodiment, the thickness of the first lens substrate, the effective area size of the first lens micro-nano structure side, the effective area size of the second lens micro-nano structure side, and the back focus distance meet the following conditions: The total optical length satisfies TTL=1.40mm; the field of view angle satisfies Fov=120°.

[0072] The wide field of view optical lens provided in this embodiment has an operating band of 940±17.5nm, an Fno of 2.4, a high resolution of 114lp / mm, and an MTF>0.2, which meets the requirements of eye tracking technology.

[0073] Figure 6 Schematic diagram of the diffuse spot of the large-field-of-view optical lens provided by an embodiment of the present invention. The large-field-of-view optical lens provided by an embodiment of the present invention has a relatively concentrated and evenly distributed diffuse pattern over the entire long-wave band, which can meet the requirements of high-resolution imaging.

[0074] Figure 7 A schematic diagram of relative illumination of a large field of view optical lens according to an embodiment of the present invention is provided, which shows relative illumination values corresponding to different fields of view, such as Figure 7 As shown, the wide-field optical lens provided by the embodiment of the present invention has a relative illumination greater than 68% in the entire field of view in the working band, and the brightness is uniform.

[0075] In summary, the large field of view optical lens provided by the embodiment of the present invention has a small size, low cost, high relative illumination, a large field of view angle, and clear imaging, and can meet the requirements of high-quality imaging and lightweight integration.

[0076] Example 1 and Example 2 respectively satisfy the relationship shown in Table 5 below.

[0077] Table 5

[0078]

[0079] An embodiment of the present invention further discloses an eye tracking system, comprising any of the above-mentioned large-field-of-view optical lenses, light sources, image sensors, and a line-of-sight estimation algorithm module.

[0080] The present invention also discloses a terminal device including the eye tracking system. It is understood that the terminal device includes, but is not limited to, VR / AR headsets, laptop computers, cyclist monitoring systems, auxiliary communication devices, and specialized research equipment.

[0081] The above are only specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A wide field of view optical lens, characterized in that: A first lens, a second lens, and a filter are sequentially arranged along the optical axis from the object plane to the image plane, and the first lens and the second lens are both metasurface lenses, and the metasurface lenses are provided with a micro-nano structure; The wide field of view optical lens meets the following requirements: Among them, M is the thickness of the first lens substrate, D1 is the effective area size of the first lens micro-nano structure side, D2 is the effective area size of the second lens micro-nano structure side, and BFL is the back focus distance, that is, the distance from the image side of the filter to the imaging surface.

2. The wide-field optical lens according to claim 1, wherein: The side of the metasurface lens provided with the micro-nano structure faces the object plane / image plane.

3. The wide-field optical lens according to claim 2, wherein: The sides of the first lens and the second lens provided with the micro-nano structure both face the object plane.

4. The wide-field optical lens according to claim 2, wherein: The sides of the first lens and the second lens provided with the micro-nano structure both face the image plane.

5. The optical lens with a large field of view according to claim 1, wherein: A distance TTL from the optical axis center of the object side surface of the first lens to the image plane satisfies: TTL≤1.40 mm.

6. The wide-field optical lens according to claim 1, wherein: The relative illumination of the large-field optical lens satisfies RI≥60%; the field of view angle satisfies Fov≥120°; and the operating temperature is -45°C to 105°C.

7. The wide-field optical lens according to claim 1, wherein: Also includes the aperture.

8. The wide-field optical lens according to claim 7, characterized in that: The aperture is disposed between the first lens and the second lens.

9. An eye tracking system, characterized in that The invention comprises any one of claims 1-8 of the optical lens with a large field of view.

10. The terminal device is characterized in that Comprising the eye tracking system as claimed in claim 9.

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