Folding and super hybrid TOF (Time of Flight) lens and three-dimensional sensing module

Abstract

The invention relates to a refraction and super hybrid TOF lens and a three-dimensional perception module, and belongs to the field of optical lenses, the lens comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object plane to an image plane along an optical axis, at least one lens is a super-surface lens, and the other lenses are non-super-surface lenses. According to the invention, the technical scheme of folding and super mixing is adopted, and the optical system with a large aperture and small distortion is realized through the four-piece design.

Description

Technical Field

[0001] The present invention belongs to the field of optical lenses, and in particular relates to a refractive-super hybrid TOF lens and a three-dimensional sensing module. Background Art

[0002] Time-of-Flight (TOF) technology is an advanced 3D imaging technique that can capture the depth information of an entire scene in one go. It is widely used in mobile phones, automobiles, industry, and other fields. TOF lenses, as a common TOF technology component, typically operate in the near-infrared band.

[0003] Common TOF lenses, depending on the application scenario and cost requirements, are often composed of a combination of glass / plastic spherical / aspherical lenses. They generally offer a wide field of view, high resolution, and minimal distortion. However, existing TOF lenses generally have a long overall optical length, making them unsuitable for applications requiring device miniaturization. Summary of the Invention

[0004] The present application provides a hybrid TOF lens and a three-dimensional sensing module to at least solve the above technical problems existing in the prior art.

[0005] On one hand, an embodiment of the present application provides a fold-metasurface hybrid TOF lens, wherein the lens includes a first lens, a second lens, a third lens, and a fourth lens, which are sequentially arranged along the optical axis from the object plane to the image plane, wherein at least one lens is a metasurface lens, and the remaining lenses are non-metasurface lenses;

[0006] The lens meets the following requirements:

[0007]

[0008] Where Fno is the aperture number, FOV is the diagonal field of view, TTL is the total length of the optical system, which is defined as the distance from the center of the optical axis of the object side of the first lens to the image plane, and ImgH is the image height corresponding to the diagonal field of view.

[0009] In one embodiment, the first lens, the third lens, and the fourth lens are all aspherical lenses; and the second lens is a metasurface lens.

[0010] In one embodiment, the first lens is a lens with positive refractive power, the object side surface of which is convex near the optical axis, and the image side surface of which is concave near the optical axis; both the object side surface and the image side surface of the first lens are aspherical surfaces;

[0011] The second lens is a metasurface lens with positive optical power, the object side of which has a microstructure arrangement and the image side is a flat surface;

[0012] The third lens is a lens with positive refractive power, the object side surface of which is concave near the optical axis, and the image side surface of which is convex near the optical axis; both the object side surface and the image side surface of the third lens are aspherical;

[0013] The fourth lens is a lens with negative optical power, and the image side surface thereof is concave near the optical axis; the object side surface and the image side surface of the fourth lens are both aspherical surfaces.

[0014] In one embodiment, the object-side surface of the fourth lens is convex near the optical axis.

[0015] In one embodiment, the object-side surface of the fourth lens is concave near the optical axis.

[0016] In one possible implementation manner, the focal length of the lens satisfies f≥1.6 mm; and the aperture number of the lens satisfies 1.6≤Fno≤2.4.

[0017] In one possible implementation manner, the field of view angle of the lens satisfies FOV≥75°; and the operating temperature of the lens is -40°C to 85°C.

[0018] In one embodiment, a stop is further included.

[0019] In one embodiment, a color filter is further included.

[0020] On the other hand, an embodiment of the present application provides a three-dimensional perception module, including any of the above-described hybrid TOF lenses.

[0021] Compared with the prior art, this application has the following advantages:

[0022] This application adopts a refractive-super hybrid technical solution, and realizes an optical system with large aperture and small distortion through a four-piece design, while compressing the total optical length to achieve a miniaturized and lightweight design. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the hybrid TOF lens in Example 1 of the present application;

[0024] Figure 2 : This is a schematic diagram of the MTF of the hybrid TOF lens in Example 1 of the present application;

[0025] Figure 3 Schematic diagram of the diffuse spots of the refractive super hybrid TOF lens in Example 1 of the present application;

[0026] Figure 4 Schematic diagram of the distortion of the refractive-super hybrid TOF lens in Example 1 of the present application;

[0027] Figure 5Schematic diagram of the structure of the hybrid TOF lens in Example 2 of the present application;

[0028] Figure 6 : This is a schematic diagram of the MTF of the super-hybrid TOF lens in Example 2 of the present application;

[0029] Figure 7 Schematic diagram of the diffuse spots of the refractive super hybrid TOF lens in Example 2 of the present application;

[0030] Figure 8 Schematic diagram of the distortion of the refractive-super hybrid TOF lens in Example 2 of the present application;

[0031] Description of reference numerals:

[0032] 100 , aperture; 110 , first lens; 120 , second lens; 130 , third lens; 140 , fourth lens; 150 , imaging plane; 160 , color filter. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below with reference to the accompanying drawings.

[0034] 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.

[0035] The present application discloses a refracted-metasurface hybrid TOF lens, wherein the lens comprises a first lens, a second lens, a third lens, and a fourth lens, which are sequentially arranged along the optical axis from the object plane to the image plane, wherein at least one lens is a metasurface lens, and the remaining lenses are non-metasurface lenses;

[0036] The lens meets the following requirements:

[0037]

[0038] Where Fno is the aperture number, FOV is the diagonal field of view, TTL is the total length of the optical system, which is defined as the distance from the center of the optical axis of the object side of the first lens to the image plane, and ImgH is the image height corresponding to the diagonal field of view.

[0039] Specifically, the operating wavelength band of the lens in this application is near-infrared. The non-metasurface lens is made of a resin material with high transmittance in the near-infrared, such as EP4000, EP5000, EP6000, EP7000, OKP4, APL5514, and APL5014. The metasurface lens can be made of silica, D263TECO, and other materials. By combining the materials and the optical power of each lens, the imaging quality of the TOF lens is improved while the system size is reduced.

[0040] In this embodiment, the metasurface lens consists of a substrate and a micro-nanostructure mounted on the substrate. This micro-nanostructure is composed of an array of subwavelength-scale micro-nanounits, each with a specific shape, size, and arrangement to precisely control the phase, amplitude, or polarization state of the incident light wave. Through the design of these micro-nanostructures, the metasurface lens achieves optical performance comparable to or even superior to that of traditional lenses, such as high transmittance, low chromatic aberration, and low distortion, while maintaining a lightweight and thin design.

[0041] In some embodiments, the first lens, the third lens, and the fourth lens are all aspherical lenses; and the second lens is a metasurface lens.

[0042] Furthermore, in some embodiments, the first lens is a lens with positive refractive power, the object-side surface of which is convex near the optical axis, and the image-side surface of which is concave near the optical axis; both the object-side surface and the image-side surface of the first lens are aspherical surfaces;

[0043] The second lens is a metasurface lens with positive optical power, whose object side has a microstructure arrangement and the image side is flat;

[0044] The third lens is a lens with positive refractive power, whose object-side surface is concave near the optical axis and whose image-side surface is convex near the optical axis; both the object-side surface and the image-side surface of the third lens are aspherical surfaces;

[0045] The fourth lens is a lens with negative optical power, and its image-side surface is concave near the optical axis; both the object-side surface and the image-side surface of the fourth lens are aspherical surfaces.

[0046] The object-side surface of the fourth lens element near the optical axis may be a concave surface or a convex surface.

[0047] Based on the above solution, the focal length of the lens satisfies f≥1.6mm; the aperture number of the lens satisfies 1.6≤Fno≤2.4; the field of view angle of the lens satisfies FOV≥75°; and the operating temperature of the lens is -40°C to 85°C.

[0048] In a preferred embodiment, any of the above lenses further includes an aperture.

[0049] Furthermore, the aperture can be arranged before the first lens, after the fourth lens, or between any two lenses.

[0050] In a preferred embodiment, any of the above lenses further includes a color filter.

[0051] Furthermore, the color filter may be arranged before the first lens or after the fourth lens.

[0052] The present application exemplarily provides two fold-super hybrid TOF lenses that meet usage requirements in two embodiments. The fold-super hybrid TOF lenses provided in the two specific embodiments of the present application are introduced in detail below.

[0053] Example 1

[0054] refer to Figure 1 This embodiment discloses a refractive-metasurface hybrid TOF lens, which includes a first lens 110, an aperture 100, a second lens 120, a third lens 130 and a fourth lens 140 arranged in sequence along the optical axis from the object plane to the image plane, wherein the first lens 110, the third lens 130 and the fourth lens 140 are all aspherical lenses; the second lens 120 is a metasurface lens.

[0055] like Figure 1 As shown, the incident light enters from the object side of the first lens 110 , passes through the aperture 100 , the second lens 120 , the third lens 130 , and the fourth lens 140 in sequence, and finally converges on the imaging surface 150 .

[0056] Specifically, the first lens 110 is an aspheric lens with positive optical power, whose object-side surface is convex near the optical axis and whose image-side surface is concave near the optical axis; the second lens 120 is a metasurface lens with positive optical power, whose object-side surface has a microstructure arrangement and whose image-side surface is flat; the third lens 130 is an aspheric lens with positive optical power, whose object-side surface is concave near the optical axis and whose image-side surface is convex near the optical axis; the fourth lens 140 is an aspheric lens with negative optical power, whose object-side surface is convex near the optical axis and whose image-side surface is concave near the optical axis.

[0057] For example, Table 1 describes in detail the specific optical data parameters of each lens in the hybrid TOF 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 super hybrid TOF lens shown.

[0058] Table 1

[0059] Surface number Face shape Curvature radius (mm) Spacing (mm) Material Diameter (mm) 1 EVENASPHERE 0.67 0.35 1.54 0.5 2 EVENASPHERE 1.27 0.04 - 0.3 3STOP STANDARD Infinity 0.11 - 0.3 4 BINARY2 Infinity 0.3 1.52 0.4 5 STANDARD Infinity 0.20 - 0.5 6 EVENASPHERE -1.15 0.24 1.63 0.6 7 EVENASPHERE -1.00 0.09 - 0.8 8 EVENASPHERE 3.00 0.40 1.54 1.1 9 EVENASPHERE 1.20 0.47 - 1.3 10IMA STANDARD Infinity - - -

[0060] The surface numbers are numbered according to the order of the surfaces of each lens. For example, surface number 1 represents the object side of the first lens 110, surface number 2 represents the image side of the first lens 110, and so on. The radius of curvature represents the degree of curvature of the lens surface near the optical axis. A positive value indicates that the surface is curved toward the image side, a negative value indicates that the surface is curved toward the object side, and "Infinity" indicates 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 spacing are both millimeters (mm). The value in the material column represents the refractive index of the corresponding lens material.

[0061] The even-order aspheric surface satisfies the following equation:

[0062]

[0063] Where z is the distance from the vertex of the even aspheric surface along the optical axis, r is the height from the optical axis, c is the curvature, c = 1 / R, R is the radius of curvature at the vertex of the lens; N is the number of polynomial coefficients in the series, k is the cone coefficient, a i is the aspheric high-order coefficient.

[0064] For example, Table 2 details the conic coefficient k and the high-order coefficient a of the aspheric lens surface in this embodiment in a feasible implementation manner. i .

[0065] Table 2

[0066]

[0067] The binary face is expanded to increase the phase according to the following polynomial:

[0068]

[0069] where N is the number of polynomial coefficients in the series, Ai is the squared coefficient of ρ, ρ is the normalized radial aperture coordinate, and M is the diffraction order.

[0070] Exemplarily, Table 3 details the binary surface coefficients of the metasurface lens in this embodiment in a feasible implementation manner.

[0071] Table 3

[0072]

[0073]

[0074] Where R1 is the normalized radius of the binary surface.

[0075] In this embodiment, the aperture number, field of view angle and total length of the system meet the following conditions: The total length of the optical lens and the image height meet the requirements

[0076] The operating band of the refractive-super hybrid TOF lens provided in this embodiment is 925-955nm, the aperture number is 2.4, the focal length is 1.72mm, the maximum full field of view angle is 89.1°, and the corresponding image height is 3.5mm, which meets the use requirements of the TOF lens.

[0077] Figure 2 This is a schematic diagram of the modulation transfer function (MTF) of the folded super hybrid TOF lens provided in an embodiment of the present invention. The folded super hybrid TOF lens provided in an embodiment of the present invention has an MTF value ≥ 0.4 within a 0.8 field of view at 100lp / mm, which can match conventional chips and meet the needs of high-resolution imaging.

[0078] Figure 3 This is a schematic diagram of the diffuse spot of the fold-super hybrid TOF lens provided in an embodiment of the present invention. The fold-super hybrid TOF lens provided in an embodiment of the present invention has a relatively concentrated and evenly distributed diffuse pattern over the entire band, which can meet the requirements of high-resolution imaging.

[0079] Figure 4 This is a schematic diagram of the distortion of the fold-super hybrid TOF lens provided by an embodiment of the present invention, which represents the distortion values ​​corresponding to different fields of view, such as Figure 4 As shown, the folded-super hybrid TOF lens provided by the embodiment of the present invention has a distortion of less than 5% in the entire field of view in the working band, and the overall distortion is small.

[0080] Example 2

[0081] refer to Figure 5 This embodiment discloses a refracted-metasurface hybrid TOF lens, which includes a first lens 110, an aperture 100, a second lens 120, a third lens 130, a fourth lens 140 and a color filter 160, which are arranged in sequence from the object plane to the image plane along the optical axis. The first lens 110, the third lens 130 and the fourth lens 140 are all aspherical lenses; the second lens 120 is a metasurface lens; the object side surface and the image side surface of the color filter 160 are both flat.

[0082] like Figure 5 As shown, the incident light enters from the object side of the first lens 110 , passes through the aperture 100 , the second lens 120 , the third lens 130 , the fourth lens 140 , and the color filter 160 in sequence, and finally converges on the imaging surface 150 .

[0083] Specifically, the first lens 110 is an aspheric lens with positive optical power, whose object-side surface is convex near the optical axis and whose image-side surface is concave near the optical axis; the second lens 120 is a metasurface lens with positive optical power, whose object-side surface has a microstructure arrangement and whose image-side surface is flat; the third lens 130 is an aspheric lens with positive optical power, whose object-side surface is concave near the optical axis and whose image-side surface is convex near the optical axis; the fourth lens 140 is an aspheric lens with negative optical power, whose object-side surface is concave near the optical axis and whose image-side surface is concave near the optical axis.

[0084] For example, Table 4 describes in detail the specific optical data parameters of each lens in the hybrid TOF lens provided by the embodiment of the present invention in a feasible implementation manner. The optical data parameters in Table 4 correspond to Figure 5 The super hybrid TOF lens shown.

[0085] Table 4

[0086]

[0087]

[0088] The surface numbers are numbered according to the order of the surfaces of each lens. For example, surface number 1 represents the object side of the first lens 110, surface number 2 represents the image side of the first lens 110, and so on. The radius of curvature represents the degree of curvature of the lens surface near the optical axis. A positive value indicates that the surface is curved toward the image side, a negative value indicates that the surface is curved toward the object side, and "Infinity" indicates 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 spacing are both millimeters (mm). The value in the material column represents the refractive index of the corresponding lens material.

[0089] The even-order aspheric surface satisfies the following equation:

[0090]

[0091] Where z is the distance from the vertex of the even aspheric surface along the optical axis, r is the height from the optical axis, c is the curvature, c = 1 / R, R is the radius of curvature at the vertex of the lens; N is the number of polynomial coefficients in the series, k is the cone coefficient, a i is the aspheric high-order coefficient.

[0092] For example, Table 5 details the conic coefficient k and the high-order coefficient a of the aspheric lens surface in this embodiment in a feasible implementation manner. i .

[0093] Table 5

[0094]

[0095]

[0096] The binary face is expanded to increase the phase according to the following polynomial:

[0097]

[0098] where N is the number of polynomial coefficients in the series, Ai is the squared coefficient of ρ, ρ is the normalized radial aperture coordinate, and M is the diffraction order.

[0099] Exemplarily, Table 6 details the binary surface coefficients of the metasurface lens in this embodiment in a feasible implementation manner.

[0100] Table 6

[0101] Surface number R1 a1 a2 a3 4 1 -6.10E+02 5.70E+02 2.12E+03 Surface number a4 a5 a6 a7 4 -1.35E+04 5.69E+04 3.17E+04 -6.32E+05

[0102] Where R1 is the normalized radius of the binary surface.

[0103] In this embodiment, the aperture number, field of view angle and total length of the system meet the following conditions: The total length of the optical lens and the image height meet the requirements

[0104] The operating band of the refractive-super hybrid TOF lens provided in this embodiment is 925-955nm, the aperture number is 1.8, the focal length is 2.10mm, the maximum full field of view angle is 78.0°, and the corresponding image height is 3.5mm, which meets the use requirements of the TOF lens.

[0105] Figure 6 This is a schematic diagram of the modulation transfer function (MTF) of the folded super hybrid TOF lens provided in an embodiment of the present invention. The folded super hybrid near-infrared TOF lens provided in an embodiment of the present invention has an MTF value ≥ 0.4 at 100lp / mm, which can match conventional chips and meet the needs of high-resolution imaging.

[0106] Figure 7 This is a schematic diagram of the diffuse spot of the fold-super hybrid TOF lens provided in an embodiment of the present invention. The fold-super hybrid TOF lens provided in an embodiment of the present invention has a relatively concentrated and evenly distributed diffuse pattern over the entire band, which can meet the requirements of high-resolution imaging.

[0107] Figure 8 This is a schematic diagram of the distortion of the fold-super hybrid TOF lens provided by an embodiment of the present invention, which represents the distortion values ​​corresponding to different fields of view, such as Figure 8 As shown, the folded-super hybrid TOF lens provided by the embodiment of the present invention has a distortion of less than 5% in the entire field of view in the working band, and the overall distortion is small.

[0108] Example 1 and Example 2 respectively satisfy the relationship shown in Table 7 below:

[0109] Table 7

[0110]

[0111] The present application also discloses a 3D sensing module, including any of the above-mentioned hybrid TOF lenses. It is understood that the application fields of the hybrid TOF lens of the present application include but are not limited to mobile phones, automobiles, and industrial fields.

[0112] In some embodiments, the three-dimensional perception module includes an integrated optical structure, a collaborative processing module and a multi-scene adaptation interface, and the integrated optical structure includes any of the above-mentioned hybrid TOF lenses.

[0113] The 3D sensing module in the embodiments of the present application may be applied to, but not limited to, the following scenarios:

[0114] 1) Mobile devices: including smartphones and AR / VR devices, used for under-screen facial recognition, gesture control, and augmented reality applications;

[0115] 2) Autonomous mobile robots: including sweeping robots and service robots, used for low-space navigation, high-precision mapping, and dynamic obstacle detection;

[0116] 3) Industrial and security equipment: including logistics volume measurement systems and crowd counting monitoring terminals, which can achieve millimeter-level precision ranging in complex lighting environments.

[0117] 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 hybrid TOF lens, characterized in that: The lens comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the optical axis from the object plane to the image plane, wherein at least one lens is a metasurface lens and the remaining lenses are non-metasurface lenses; The lens meets the following requirements: Where Fno is the aperture number, FOV is the diagonal field of view, TTL is the total length of the optical system, which is defined as the distance from the center of the optical axis of the object side of the first lens to the image plane, and ImgH is the image height corresponding to the diagonal field of view.

2. The hybrid TOF lens according to claim 1, characterized in that: The first lens, the third lens, and the fourth lens are all aspherical lenses; and the second lens is a metasurface lens.

3. The hybrid TOF lens according to claim 2, characterized in that: The first lens is a lens with positive refractive power, the object side surface of which is convex near the optical axis, and the image side surface of which is concave near the optical axis; both the object side surface and the image side surface of the first lens are aspherical surfaces; The second lens is a metasurface lens with positive optical power, the object side of which has a microstructure arrangement and the image side is a flat surface; The third lens is a lens with positive refractive power, the object side surface of which is concave near the optical axis, and the image side surface of which is convex near the optical axis; both the object side surface and the image side surface of the third lens are aspherical; The fourth lens is a lens with negative optical power, and the image side surface thereof is concave near the optical axis; the object side surface and the image side surface of the fourth lens are both aspherical surfaces.

4. The hybrid TOF lens according to claim 3, characterized in that: The object side surface of the fourth lens is convex near the optical axis.

5. The hybrid TOF lens according to claim 3, characterized in that: The object side surface of the fourth lens is concave near the optical axis.

6. The hybrid TOF lens according to claim 1, characterized in that: The focal length of the lens satisfies f≥1.6mm; the aperture number of the lens satisfies 1.6≤Fno≤2.

4.

7. The hybrid TOF lens according to claim 1, characterized in that: The field of view angle of the lens satisfies FOV≥75°; the operating temperature of the lens is -40°C to 85°C.

8. The hybrid TOF lens according to claim 1, characterized in that: Also includes the aperture.

9. The hybrid TOF lens according to claim 1, characterized in that: Also includes color filters.

10. The three-dimensional perception module is characterized by: The invention comprises the hybrid TOF lens described in any one of claims 1 to 9.

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