Miniaturized dTOF receiving lens, dTOF receiving end and dTOF module

Abstract

The invention relates to a miniaturized dTOF receiving lens, a dTOF receiving end and a dTOF module, and belongs to the field of optical lenses, and the miniaturized dTOF receiving lens comprises a first lens and a diaphragm. The volume and the weight of the receiving lens are reduced by utilizing the technical scheme of the metasurface, the receiving lens can be conveniently integrated into a dTOF module, and miniaturization, light weight and integrated design can be realized. Meanwhile, the manufacturing process of the metasurface is relatively simple, conventional photoetching, etching, sputtering, spraying and other methods can be adopted, and the production cost can be reduced.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the field of optical lenses, in particular to a miniaturized dTOF receiving lens, a dTOF receiving end and a dTOF module. BACKGROUND

[0002] The dTOF technology is a technology for directly calculating the distance between an object and a sensor by measuring the time difference of a light pulse from emission to reflection back. The dTOF technology is widely used in many fields, such as face recognition, AR / VR intelligent interaction, auxiliary focusing, etc. in smart phones; in the automotive field, as one of the core technologies of laser radar, it provides environmental perception and obstacle detection for autonomous driving; in industrial automation, it is used for robot navigation, industrial ranging, material detection, etc.; in smart home, it can realize intelligent door lock recognition, intelligent body interaction, etc.; in addition, it is also widely used in unmanned aerial vehicles, security monitoring, medical equipment, etc.

[0003] The dTOF module usually includes a transmitting end, a receiving end and a signal processing unit. The transmitting end includes a VCSEL light source and an optical assembly. The VCSEL light source can emit modulated near-infrared light to the object to provide stable light signals for dTOF ranging, and the optical assembly includes a collimating lens, a diffractive optical element (DOE) and a filter, etc. The receiving end includes a single photon avalanche diode (SPAD) and an imaging receiving lens. The imaging receiving lens is used to focus the light reflected from the target object and image it on the SPAD to improve the collection efficiency and imaging quality of the light signal, helping the SPAD to more accurately detect the light signal and thus improve the ranging accuracy.

[0004] The traditional dTOF receiving lens is usually a lens group composed of multiple lenses, which makes the dTOF module bulky and heavy. Due to the volume and weight restrictions, the traditional receiving lens faces great challenges when integrated into consumer electronic products such as smart phones. Moreover, the traditional lens has the problem of high cost. Traditional high-quality optical lenses require precise machining and manufacturing processes, and the cost is relatively high, especially for some high-precision and high-performance dTOF application scenarios such as industrial measurement and autonomous driving, the cost of the lens will further increase. Therefore, how to realize the miniaturization, lightweight and integration of the dTOF receiving lens, the dTOF receiving end and the dTOF module, and reduce the processing cost is the current technical difficulty. SUMMARY

[0005] The present application provides a miniaturized dTOF receiving lens, which reduces the size and cost of the lens while ensuring the field of view, focal length and aperture number, improves the resolution and relative luminance, and realizes non-thermal design.

[0006] The embodiment of the present application provides a miniaturized dTOF receiving lens, the lens comprising a first lens and a diaphragm; The first lens is a super surface lens with positive focal power, which is composed of a substrate and a super surface micro-nano structure arranged on the substrate, and the object side of the first lens is a plane, and the image side has a super surface micro-nano structure. The diaphragm is located in the optical path behind the first lens or on the image side of the first lens.

[0007] Optionally, the miniaturized dTOF receiving lens satisfies: ; Wherein, is the effective focal length of the miniaturized dTOF receiving lens, is the distance from the image side of the super surface lens to the imaging plane, is the effective aperture of the super surface lens, is the quadratic phase coefficient of the super surface lens.

[0008] Optionally, the substrate material of the first lens is amorphous silicon, crystalline silicon, borosilicate, silicon dioxide, quartz or glass, and the substrate thickness is 0.3-1.0mm; The super surface micro-nano structure material of the first lens is amorphous silicon, crystalline silicon, silicon dioxide, silicon nitride or titanium dioxide; the period of the super surface micro-nano structure of the first lens ranges from 350-500nm, and the height ranges from 500-1500nm; the diameter coverage range of the super surface micro-nano structure of the first lens ranges from 100-350nm, and is arranged in a square or regular hexagon.

[0009] Further, the period of the super surface micro-nano structure of the first lens is 450nm, and the height is 700nm.

[0010] Optionally, the distance from the optical axis center of the object side of the first lens to the imaging plane is the total length of the optical system TTL , and satisfies: .

[0011] Optionally, the miniaturized dTOF receiving lens further comprises a diaphragm, and the diaphragm is located in the optical path behind the first lens or on the image side of the first lens.

[0012] Optionally, the relative luminance of the miniaturized dTOF receiving lens RI satisfies: .

[0013] Optionally, the aperture number of the miniaturized dTOF receiving lens satisfies: .

[0014] Optionally, the operating temperature of the miniaturized dTOF receiving lens is -45℃ to 105℃.

[0015] The present invention also provides a miniaturized dTOF receiver, which includes the miniaturized dTOF receiving lens described above.

[0016] The present invention also provides a miniaturized dTOF module, which includes the miniaturized dTOF receiver described above.

[0017] This invention provides a miniaturized dTOF receiving lens that utilizes a single metasurface lens. This results in a small size and cost-effectiveness while maintaining an operating temperature range of -45℃ to 105℃. Furthermore, by rationally allocating the phase of the metasurface, the miniaturized dTOF receiving lens satisfies the following requirements: Furthermore, the miniaturized TOF receiving lens has a higher resolution, in Central field of view Edge field of view At the same time, the relative illuminance meets the requirements. The imaging field of view satisfies Total length of optical system This addresses the issues of large size and high cost in existing dTOF receiving lenses. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the MTF of a miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the blur pattern of a miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention; Figure 4 This is a distortion diagram of a miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of a miniaturized dTOF receiving lens provided in Embodiment 2 of the present invention; Figure 6 This is a schematic diagram of the MTF of a miniaturized dTOF receiving lens provided in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram of the blur pattern of a miniaturized dTOF receiving lens provided in Embodiment 2 of the present invention; Figure 8 This is a distortion diagram of a miniaturized dTOF receiving lens provided in Embodiment 2 of the present invention.

[0019] Explanation of reference numerals in the attached figures: 110, first lens; 120, diaphragm; 130, imaging surface. DETAILED DESCRIPTION

[0020] The application will be further described in detail below with reference to the accompanying drawings.

[0021] A metasurface is a two-dimensional metamaterial composed of sub-wavelength artificial micro-nano structures (such as nano-antennas, etc.) arranged in a certain pattern. By precisely designing the geometric shape, size, arrangement, etc. of these micro-nano structures, the phase, amplitude, polarization, propagation direction, etc. of electromagnetic waves can be controlled with sub-wavelength resolution, realizing flexible regulation of electromagnetic waves. The thickness of the metasurface is usually much smaller than the wavelength of light, and it has the characteristics of thinness and compactness, which is convenient for integration with various devices, such as portable electronic devices such as mobile phones and tablet computers, to realize smaller optical imaging systems, sensor function modules, etc. It can also be used to make ultra-thin optical elements to reduce the volume and weight of the device. The manufacturing of metasurfaces can use mature semiconductor processes such as photolithography and etching, which have high processing precision and repeatability, and can be mass-produced to reduce manufacturing costs, making it have a wider application prospect in many fields.

[0022] The dTOF receiving lens made of metasurfaces can well solve the problems existing in traditional dTOF receiving lenses. The metasurface lens system can usually realize ultra-thin optical elements, can achieve the required optical performance in a relatively small optical system, helps to reduce the volume and weight of the optical system, and has relatively high imaging resolution and relative luminance, can realize high-quality imaging, and has relatively low manufacturing cost.

[0023] The micro dTOF receiving lens provided by the embodiment of the application comprises a first lens 110 and a diaphragm 120. The first lens 110 is a metasurface lens with positive focal power, which is composed of a substrate and metasurface micro-nano structures arranged on the substrate. The object side of the first lens 110 is a plane, and the image side has metasurface micro-nano structures.

[0024] The diaphragm 120 is located in the optical path after the first lens 110 or on the image side of the first lens 110. The diaphragm 120 is mainly used to control the path of light passing through the lens and reduce the interference of stray light, thereby improving the imaging quality.

[0025] The metasurface lens can effectively correct aberration and provide high-quality imaging effect, so that the micro dTOF receiving lens meets the following requirements: ; Wherein, is the effective focal length of the micro dTOF receiving lens, A distance from an image side surface of the metasurface lens to the imaging surface 130, An effective area diameter of the metasurface lens, A quadratic phase coefficient of the metasurface lens.

[0026] In the present application, the base material of the first lens 110 includes but is not limited to amorphous silicon, crystalline silicon, borosilicate, silicon dioxide, quartz, glass, and the base thickness is 0.3-1.0 m. The material of the metasurface micro-nano structure of the first lens 110 includes but is not limited to amorphous silicon, crystalline silicon, silicon dioxide, silicon nitride, and titanium dioxide. Through the cooperation of the base and the material of the metasurface micro-nano structure, the athermal design is realized, which not only reduces the material cost, but also simplifies the structure of the optical system and reduces the volume of the system.

[0027] At the same time, each metasurface micro-nano structure of the first lens 110 has a specific shape, size and arrangement mode to realize the accurate regulation of the phase, amplitude or polarization state of the incident light wave. Through the design of the metasurface micro-nano structure, the metasurface lens can realize the optical performance equivalent to or even better than the traditional lens while maintaining a light and thin volume, such as high light transmittance, low chromatic aberration, low distortion, etc. The period of the metasurface micro-nano structure of the first lens 110 ranges from 350-500 nm, and the optimal period in the present embodiment is 450 nm; the height ranges from 500-1500 nm, and the optimal height in the present embodiment is 700 nm; the diameter coverage range of the metasurface micro-nano structure of the first lens 110 is 100-350 nm, and the arrangement is square or regular hexagonal.

[0028] Based on the above scheme, the relative luminance of the miniaturized dTOF receiving lens satisfies , the imaging field of view angle satisfies , the total length of the optical system is , and the working temperature range is -45℃-105℃, so that the optical total length of the miniaturized dTOF receiving lens is shorter, the field of view angle is larger, and the overall volume is smaller. At the same time, the resolution of the miniaturized dTOF receiving lens provided by the present embodiment is higher, and the , the central field of view , and the edge field of view . Embodiment

[0029] Reference Figure 1 The miniaturized dTOF receiving lens provided by the present embodiment 1 includes a first lens 110, a diaphragm 120 and an imaging surface 130.

[0030] The first lens 110 is a super surface lens with positive focal length, which is composed of a substrate and a super surface micro-nano structure arranged on the substrate. The object side of the first lens 110 is a plane, and the image side has a super surface micro-nano structure. In the embodiment 1 of the present application, the diaphragm 120 is located on the image side of the first lens 110.

[0031] As shown in the figure, the incident light enters through the object side of the first lens 110, passes through the diaphragm 120, and finally converges on the imaging surface 130. Figure 1

[0032] Exemplarily, Table 1 details the specific optical data parameters of each lens in the miniaturized dTOF receiving lens provided by the embodiment 1 of the present application in a feasible implementation manner. The optical data parameters in Table 1 correspond to the miniaturized dTOF receiving lens shown in the figure. Figure 1

[0033] Table 1

[0034] In the table, the surface number is numbered according to the surface order of each lens. The surface number 1 represents the object side of the first lens 110, the surface number 2 represents the image side of the first lens 110 and the diaphragm 120, and the surface number 3 represents the imaging surface 130. The curvature radius represents the bending degree of the lens surface. A positive value represents that the surface is bent towards the image side, and a negative value represents that the surface is bent towards the object side. Infinity represents infinity, Standard represents a standard surface, and Binary2 represents a binary surface. The interval represents the center axis distance from the current surface to the next surface. The units of the curvature radius, the interval, and the focal length are millimeters (mm).

[0035] Exemplarily, Table 2 details the phase of the super surface in the embodiment 1 in a feasible implementation manner.

[0036] Table 2

[0037] In the table, R1 is the normalized radius of the binary surface.

[0038] In the embodiment 1, the effective focal length of the miniaturized dTOF receiving lens , the distance from the image side of the super surface lens to the imaging surface 130 , the effective aperture of the super surface lens , and the quadratic phase coefficient of the super surface lens satisfy ; the total optical length satisfies ; the field of view angle satisfies ; and the relative luminance satisfies . ​​

[0039] The miniaturized dTOF receiving lens provided in this embodiment 1 operates in the 940±8nm band.

[0040] Figure 2 This is a schematic diagram of the MTF of the miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention. The miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention has high resolution. Central field of view Edge field of view This meets the usage requirements of dTOF modules.

[0041] Figure 3 This is a schematic diagram of the blur pattern of the miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention. The miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention has a relatively concentrated and uniformly distributed blur pattern across the entire long-wavelength band, which can meet the requirements of high-resolution imaging.

[0042] Figure 4 This is a distortion diagram of the miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention. The miniaturized dTOF receiving lens provided in Embodiment 1 of the present invention has small distortion and small image deformation, which can meet the requirements of high-quality imaging. Example

[0043] refer to Figure 5 The present invention provides a miniaturized dTOF receiving lens in embodiment 2, comprising a first lens 110, an aperture 120 and an imaging plane 130.

[0044] The first lens 110 is a metasurface lens with positive optical power, consisting of a substrate and a metasurface micro / nanostructure disposed on the substrate. The object side of the first lens 110 is planar, and the image side has a metasurface micro / nanostructure. In Embodiment 2 of the present invention, the aperture stop 120 is located in the optical path after the first lens 110.

[0045] like Figure 5 As shown, the incident light enters through the object side of the first lens 110, passes through the aperture 120, and finally converges on the imaging surface 130.

[0046] For example, Table 3 details the specific optical data parameters of each lens in a miniaturized dTOF receiving lens provided in Embodiment 2 of the present invention, according to a feasible implementation. The optical data parameters in Table 3 correspond to... Figure 5 The miniaturized dTOF receiving lens shown.

[0047] Table 3

[0048] Wherein, the surface number is numbered according to the surface sequence of each lens, the surface number 1 represents the object side surface of the first lens 110, the surface number 2 represents the image side surface of the first lens 110, the surface number 3 represents the diaphragm 120, and the surface number 4 represents the imaging surface 130. Wherein, the radius of curvature represents the bending degree of the lens surface, the positive value represents that the surface bends to the image side, and the negative value represents that the surface bends to the object side, wherein "Infinity" represents infinity, "Standard" represents a standard surface, and "Binary2" represents a binary surface; the interval represents the center axis distance from the current surface to the next surface, and the units of the radius of curvature, the interval and the focal length are millimeters (mm).

[0049] For example, Table 4 details the phase of the super surface in the present embodiment 2 in a possible implementation manner.

[0050] Table 4

[0051] Wherein, R1 is the normalized radius of the binary surface.

[0052] In the present embodiment, the effective focal length of the miniaturized dTOF receiving lens , the distance from the image side surface of the super surface lens to the imaging surface 130 , the effective aperture of the super surface lens , and the quadratic phase coefficient of the super surface lens satisfy ; the total optical length satisfies ; the field of view angle satisfies ; and the relative luminance satisfies .

[0053] The working waveband of the miniaturized dTOF receiving lens provided by the present embodiment 2 is 940±8nm.

[0054] Figure 6 The MTF diagram of the miniaturized dTOF receiving lens provided by the present embodiment 2 of the present application is shown, and the miniaturized dTOF receiving lens provided by the present embodiment 2 has high resolution, and in , the central field of view , the edge field of view , satisfies the use requirement of the dTOF module.

[0055] Figure 7 The diffraction spot diagram of the miniaturized dTOF receiving lens provided by the present embodiment 2 of the present application is shown, and the miniaturized dTOF receiving lens provided by the present embodiment 2 has a relatively concentrated diffraction pattern and uniform distribution on the entire long waveband, and can satisfy the requirement of high resolution imaging.

[0056] Figure 8As shown in the distortion schematic diagram of the miniaturized dTOF receiving lens provided in Embodiment 2 of the present application, the miniaturized dTOF receiving lens provided in Embodiment 2 of the present application has smaller distortion and smaller image deformation degree, and can meet the requirement of high-quality imaging.

[0057] In summary, the miniaturized dTOF receiving lens provided in Embodiments 1 and 2 of the present application has small volume, low cost, clear imaging, and can meet the requirements of high-quality imaging and integration and lightness.

[0058] Embodiments 1 and 2 respectively meet the following relationships shown in Table 5: Table 5

[0059] The present application also provides a miniaturized dTOF receiving end comprising the above-mentioned miniaturized dTOF receiving lens.

[0060] The present application also provides a miniaturized dTOF module comprising the above-mentioned miniaturized dTOF receiving end.

[0061] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0062] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A miniaturized dTOF receiving lens, characterized in that, Includes the first lens and the aperture stop; The first lens is a metasurface lens with positive optical power, consisting of a substrate and a metasurface micro / nano structure disposed on the substrate. The object side of the first lens is a plane, and the image side has a metasurface micro / nano structure. The aperture stop is located in the optical path after the first lens, or on the image side of the first lens.

2. The miniaturized dTOF receiving lens according to claim 1, characterized in that, The miniaturized dTOF receiving lens satisfies: ； in, To achieve the effective focal length of a miniaturized dTOF receiving lens, This is the distance from the image-side surface of the metasurface lens to the imaging plane. The effective aperture of the metasurface lens, is the second phase coefficient of the metasurface lens.

3. The miniaturized dTOF receiving lens according to claim 1, characterized in that, The substrate material of the first lens is amorphous silicon, crystalline silicon, borosilicate, silicon dioxide, quartz, or glass, and the substrate thickness is 0.3-1.0 mm. The metasurface micro / nano structure material of the first lens is amorphous silicon, crystalline silicon, silicon dioxide, silicon nitride, or titanium dioxide; the period range of the metasurface micro / nano structure of the first lens is 350-500nm, and the height is 500-1500nm; the diameter range of the metasurface micro / nano structure of the first lens is 100-350nm, and it is arranged in a square or regular hexagonal pattern.

4. The miniaturized dTOF receiving lens according to claim 3, characterized in that, The metasurface micro / nano structure of the first lens has a period of 450 nm and a height of 700 nm.

5. The miniaturized dTOF receiving lens according to claim 1, characterized in that, The distance from the center of the optical axis on the object side of the first lens to the image plane is the total length of the optical system. TTL ,satisfy: .

6. The miniaturized dTOF receiving lens according to claim 1, characterized in that, The relative illumination of the miniaturized dTOF receiving lens RI satisfy: .

7. The miniaturized dTOF receiving lens according to claim 1, characterized in that, The aperture of the miniaturized dTOF receiving lens satisfy: .

8. The miniaturized dTOF receiving lens according to claim 1, characterized in that, The operating temperature of the miniaturized dTOF receiving lens is -45℃ to 105℃.

9. A miniaturized dTOF receiver, characterized in that, Including the miniaturized dTOF receiving lens as described in claims 1 to 8.

10. A miniaturized dTOF module, characterized in that, Includes the miniaturized dTOF receiver as described in claim 9.

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