Tof emission module and tof system having same

Abstract

Provided in the present invention are a ToF emission module and a ToF system having same. The ToF emission module comprises a radiation source and an emission metalens located on a light-emission side of the radiation source, wherein the emission metalens is used for modulating an emergent light beam emitted by the radiation source, so as to form a point cloud illumination pattern on a target surface; and the emission metalens comprises a plurality of metastructure units arranged in an array, and the plurality of metastructure units of the emission metalens are aperiodically arranged. After an emergent light beam of a radiation source is modulated by using an emission metalens, a point cloud illumination pattern is generated, and thus the size and weight of a ToF emission module are reduced.

Description

ToF transmitting module and ToF system having the same

[0001] This application is based on the Chinese patent application with application number 202311139605.4 and application date September 5, 2023, and claims the priority of the aforementioned Chinese patent application. The entire content of the above-mentioned patent application is hereby introduced into this application as a reference. Technical Field

[0002] The present invention relates to the field of optical ranging, and in particular to a ToF transmitting module and a ToF system having the same. Background Art

[0003] ToF, or Time of Flight, is a 3D measurement technology. Its principle is that a transmitting module emits a light pulse to the object being measured, and a receiving module receives the light pulse returned from the object. The depth information of the measured object is calculated by calculating the flight time of the light pulse.

[0004] Existing ToF transmitting modules use traditional lenses and diffraction optical elements to collimate the light beam and generate point clouds, which has the problems of large volume and heavy weight. Summary of the Invention

[0005] The object of the present invention is to provide a ToF transmitting module with reduced volume and weight and a ToF system having the same.

[0006] To achieve one of the above-mentioned purposes of the invention, one embodiment of the present invention provides a ToF emission module, comprising a radiation source and an emitting super-lens located on the light-emitting side of the radiation source, wherein the emitting super-lens is used to modulate the outgoing light beam emitted by the radiation source to form a point cloud illumination pattern on the target surface, and the emitting super-lens includes a plurality of super-structure units arranged in an array, and the plurality of super-structure units of the emitting super-lens are arranged non-periodically.

[0007] As a further improvement of one embodiment of the present invention, the emitting superlens arranges superstructure units of different period values ​​correspondingly based on different incident angles of the radiation source.

[0008] As a further improvement of one embodiment of the present invention, the emitting superlens has a first region and a second region in which superstructure units are arranged, the first region is closer to the center of the emitting superlens than the second region, and the period value of the superstructure units in the second region is smaller than the period value of the superstructure units in the first region.

[0009] As a further improvement of one embodiment of the present invention, the radial period of the superstructure units in the second region is correspondingly smaller than the radial period of the superstructure units in the first region, and / or the circumferential period of the superstructure units in the second region is correspondingly smaller than the circumferential period of the superstructure units in the first region.

[0010] As a further improvement of one embodiment of the present invention, the radial period of each superstructure unit of the emitting superlens decreases from the first region to the second region, and the circumferential period of each superstructure unit of the emitting superlens is equal.

[0011] As a further improvement of one embodiment of the present invention, the radial period and the circumferential period of each superstructure unit of the emitting superlens decrease from the first region to the second region.

[0012] As a further improvement of one embodiment of the present invention, the emitting metalens further has a third region in which the superstructure units are arranged. The centers of the first, third, and second regions coincide with each other, and the outer diameters increase successively. The radial period and / or circumferential period of the superstructure units in the third region decreases from the first region to the second region.

[0013] As a further improvement of an embodiment of the present invention, the radial period and the circumferential period of the superstructure units in the first region and / or the second region remain unchanged.

[0014] As a further improvement of an embodiment of the present invention, the radial period and / or circumferential period of the superstructure units in the third region decreases proportionally from the first region to the second region.

[0015] As a further improvement of one embodiment of the present invention, the emitting superlens is configured as a transmissive superlens or a reflective superlens.

[0016] As a further improvement of one embodiment of the present invention, a nanostructure is provided at the center and / or vertex position of each superstructure unit of the emitting superlens. Based on the phase distribution of the nanostructure, the emitting superlens collimates and diffracts the outgoing light beam.

[0017] As a further improvement of one embodiment of the present invention, the emitting superlens further includes a substrate connecting the nanostructures, a filler connecting the nanostructures and the substrate, and at least one antireflection film provided on the substrate and / or the filler.

[0018] As a further improvement of one embodiment of the present invention, an anti-reflection film is provided at least between the nanostructure of the emitting superlens and the substrate.

[0019] As a further improvement of one embodiment of the present invention, the emitting superlens further includes a substrate connecting the nanostructure, a filler connecting the nanostructure and the substrate, and an anti-reflection film provided on the substrate and / or the filler, wherein the anti-reflection film includes a first material layer and a second material layer, and the first material layer or the second material layer is connected to the emitting superlens.

[0020] To achieve the purpose of the above invention, the present invention also provides a ToF system, which includes the ToF transmitting module as described above and a ToF receiving module corresponding to the ToF transmitting module, and the ToF receiving module includes a receiving lens, and the receiving lens is configured to receive a super lens or a traditional lens combination.

[0021] As a further improvement of one embodiment of the present invention, the receiving super-lens includes a plurality of super-structure units arranged in an array, and the plurality of super-structure units of the receiving super-lens are arranged non-periodically.

[0022] Compared with the prior art, in an embodiment of the present invention, an emitting superlens is used to modulate the outgoing light beam of the radiation source to generate a point cloud illumination pattern, thereby reducing the volume and weight of the ToF emission module. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic structural diagram of a ToF transmitting module in a preferred embodiment of the present invention;

[0024] FIG2 is a schematic diagram of the optical path of the ToF emission module in FIG1 and a top view of the emission metalens;

[0025] Figure 3 is a top view of an emitting superlens in one preferred embodiment of the present invention;

[0026] FIG4 is a top view of an emitting metalens in another preferred embodiment of the present invention;

[0027] FIG5 is a schematic diagram of the light path at the emitting super lens in FIG2 ;

[0028] FIG6 is a cross-sectional view of point A in FIG5 according to an embodiment;

[0029] FIG7 is another embodiment of the cross-sectional view at point A in FIG5;

[0030] FIG8 is a schematic structural diagram of a ToF system in a preferred embodiment of the present invention;

[0031] FIG9 is a schematic structural diagram of a ToF system in another preferred embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by those skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0033] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0034] Furthermore, it should be understood that although the terms "first," "second," etc. may be used herein to describe various elements or structures, these described objects should not be limited by these terms. The above terms are merely used to distinguish these described objects from each other. For example, a first region may be referred to as a second region, and similarly, a second region may be referred to as a first region, without departing from the scope of protection of this application.

[0035] In the various drawings of the present invention, for the sake of convenience, some sizes of structures or parts are exaggerated relative to other structures or parts, and thus, only the basic structure of the subject matter of the present invention is illustrated.

[0036] Referring to Figure 1 , a ToF transmitting module includes a radiation source 20 and an emitting metalens 10 located on the light-emitting side of the radiation source 20. In this embodiment, the operating wavelength of the radiation source 20 can be in the infrared band (e.g., the near-infrared band) or the visible light band. The radiation source 20 and the emitting metalens 10 are arranged coaxially and located at the focal plane of the emitting metalens 10.

[0037] Specifically, the ToF emission module further includes a base 40 and a bracket 50, wherein the base 40 is used to mount the radiation source 20 and the bracket 50, and the bracket 50 is used to support the emission metalens 10. The bracket 50 can also be used to shield ambient light from entering the module from the side.

[0038] Furthermore, the emitting metalens 10 is used to modulate the outgoing light beam emitted by the radiation source 20 to form a point cloud illumination pattern on the target surface. In this embodiment, the outgoing light beam emitted by the radiation source 20, after being modulated by the emitting metalens 10, can generate a point cloud and form a point cloud illumination pattern on the target surface (i.e., the surface of the detection object).

[0039] To ensure light intensity, the radiation source 20 can be an array of multiple point radiation sources 21. Preferably, to ensure a complete image in the center of the generated point cloud illumination pattern, the radiation source 20 is arranged with an odd-number x odd-number of point radiation sources 21, thereby maintaining symmetry and obtaining a more accurate point cloud illumination pattern.

[0040] Specifically, the radiation source 20 can be configured as a vertical cavity surface emitting laser (VCSEL) array, a light emitting diode (LED) array, a solid laser or an edge emitting laser (EEL) array. The radiation source 20 can also be configured as an array of multiple point radiation 21 composed of the aforementioned lasers and / or light emitting diodes.

[0041] Furthermore, the emitting metalens 10 is configured as a transmissive metalens or a reflective metalens. In this embodiment, the emitting metalens 10 is preferably a transmissive metalens. When the outgoing light beam of the radiation source 20 is incident on the emitting metalens 10, the modulation of the outgoing light beam of the radiation source 20 by the emitting metalens 10 forms a direct projection similar to refraction. In order to increase the detection distance of the ToF emission module, the emitting metalens 10 can optionally adopt a telephoto transmissive metalens.

[0042] Of course, in an embodiment not shown, the emitting metalens 10 can also be configured as a reflective metalens. Thus, when the outgoing light beam from the radiation source 20 is incident on the emitting metalens 10, it is reflected by the emitting metalens 10 to form a point cloud illumination pattern, thereby reducing the size of the ToF transmitting module.

[0043] 2 , the emitting metalens 10 specifically includes a plurality of arrayed superstructure units 12. In this embodiment, the metalens (i.e., the emitting metalens 10) is a metasurface, which is a subwavelength artificial nanostructure film. The superstructure units 12 disposed thereon can modulate the amplitude, phase, and polarization of incident light.

[0044] Specifically, a nanostructure 123 is provided at the center and / or vertex of each superstructure unit 12 of the emitting metalens 10. In this embodiment, the nanostructure 123 can be understood as a subwavelength structure containing all dielectrics or plasmons that can cause phase mutations, and the superstructure unit 12 is a structural unit centered on each nanostructure 123 obtained by dividing the metalens (i.e., the emitting metalens 10).

[0045] Specifically, the emitting superlens 10 further includes a substrate 11 to which the nanostructures 123 are connected. In this embodiment, a plurality of nanostructures 123 are arranged on the substrate 11, wherein the nanostructures 123 in each period constitute a superstructure unit 12. The superstructure unit 12 is a densely packed pattern, such as a regular quadrilateral, a regular hexagon, a fan, etc., each period contains a nanostructure 123, and the vertices and / or center of the superstructure unit 12 can be provided with a nanostructure 123. In the case where the superstructure unit 12 is a regular hexagon, at least one nanostructure 123 is provided at each vertex and center of the regular hexagon. Similarly, the same is true for fan-shaped and square shapes.

[0046] Furthermore, the nanostructure 123 is configured as a polarization-dependent structure or a polarization-independent structure. In this embodiment, the nanostructure 123 can be configured as either a polarization-dependent structure or a polarization-independent structure depending on the application scenario. Polarization-independent structures include, for example, cylindrical, square, cross-shaped, or square-shaped cylinders with circular holes. Polarization-dependent structures include, for example, elliptical cylinders, rectangular cylinders, and hexagonal prisms.

[0047] The substrate 11 can be made of a translucent or opaque material. When the substrate 11 transmits light, it forms a transmissive metasurface, i.e., a transmissive metalens. When the substrate 11 is opaque or reflects light, it forms a reflective metasurface, i.e., a reflective metalens. Materials for the substrate 11 include, but are not limited to, quartz glass, crystalline and amorphous silicon, aluminum oxide, silicon nitride, and calcium fluoride. Materials for the nanostructures 123 include, but are not limited to, titanium oxide, tantalum oxide, hafnium oxide, silicon nitride, photoresist, quartz glass, aluminum oxide, crystalline and amorphous silicon, gallium nitride, crystalline germanium, selenium sulfide, selenium sulfide, and chalcogenide glass.

[0048] In addition, the nanostructure 123 may be located on the side of the substrate 11 facing the radiation source 20 , or may be located on the side of the substrate 11 facing away from the radiation source 20 .

[0049] Specifically, based on the phase distribution of the nanostructures 123, the emitting metalens 10 collimates and diffracts the outgoing light beam. In this embodiment, the phase distribution required for collimation and point cloud generation (i.e., diffraction beam splitting) is calculated, and appropriate metalens 12 are selected and arranged in an array based on the phase distribution. This allows the emitting metalens 10 to integrate both collimation and point cloud generation functions.

[0050] Furthermore, the multiple superstructure units 12 of the emitting metalens 10 are arranged non-periodically. In this embodiment, at least a portion of the superstructure units 12 of the emitting metalens 10 are arranged non-periodically, and the periodic values ​​of these superstructure units 12 are unequal, while the periodic values ​​of the superstructure units 12 in other portions of the emitting metalens 10 can be equal or unequal, thereby meeting the modulation effect of the emitting metalens 10 under different requirements (such as the modulation effect requirement under large angle of incidence).

[0051] Furthermore, the emitting metalens 10 arranges superstructure units 12 with different periodic values ​​corresponding to different incident angles of the radiation source 20. In this embodiment, the periodic value of the superstructure units 12 on the emitting metalens 10 can be selected based on the incident angle, thereby forming a superstructure unit 12 with different periodic values ​​corresponding to different incident angles. Compared to a constant periodicity, this avoids the phase shift that occurs with increasing incident angle, thereby better modulating each incident angle and improving the transmittance at different incident angles.

[0052] Furthermore, the emitting metalens 10 has a first region 101 and a second region 102 in which superstructure units 12 are arranged. In this embodiment, the emitting metalens 10 includes at least two regions. After the emitting metalens 10 is divided into different regions, one or more superstructure units 12 can be arranged in each region. The number of superstructure units 12 is obtained based on the arrangement function, and the structural parameters of the superstructure units 12 can be obtained based on the corresponding phase distribution formula. The superstructure units 12 in the same region can have the same period or different periods.

[0053] For ease of description, the following embodiments are all based on FIG. 2 as an example. When the same radiation source 20 is used to illuminate the emitting metalens 10, the incident angles of light at different locations on the emitting metalens 10 are different. Within the same incident plane, the emitting metalens 10 is divided into regions according to the different incident angles. Furthermore, the regions do not overlap with each other and can be adjacent or spaced apart.

[0054] Furthermore, the center of the first region 101 coincides with the center of the second region 102. In this embodiment, the superstructure units 12 on the emitting metalens 10 are preferably distributed in a ring shape, and the ring shape can be a closed structure as shown in FIG2 or an open structure. Therefore, the center of each region is at the center of the ring shape, that is, at point C in FIG2. Moreover, the center point C and the focus of the emitting metalens 10 are arranged along the Z-axis direction. For example, the radiation source 20 in FIG2 is orthogonal to the center point C. The radiation source 20 and the emitting metalens 10 are arranged on the same optical axis, and the radiation source 20 is located in the focal plane of the emitting metalens 10.

[0055] Specifically, the first region 101 is closer to the center of the emitting metalens 10 than the second region 102 , and the period value of the superstructure unit 12 in the second region 102 is smaller than the period value of the superstructure unit 12 in the first region 101 .

[0056] In this embodiment, the incident angles of light irradiated by the radiation source 20 on the first region 101 and the second region 102 are different, namely, the incident angle on the second region 1021 is greater than the incident angle on the first region 101. In this case, the light irradiated on the second region 102 is incident at a larger angle than that on the first region 101. By setting the period value of the superstructure units 12 in the second region 102 to be smaller than that of the superstructure units 12 in the first region 101, the superstructure units 12 in the second region 102 have a better modulation effect on light incident at larger angles, making it suitable for large numerical aperture (NA) systems and improving the efficiency of large NA systems.

[0057] Therefore, when the emitting superlens 10 collimates and diffracts the outgoing light beam, it avoids the phase change rate of the emitting superlens 10 being too fast at the position away from the center point C under large NA and large field of view, and more superstructure units 12 with 0-2π phase coverage are achieved, which is beneficial to improving the transmittance of the emitting superlens 10 for large-angle incident light, reducing the requirements for the distance between the emitting superlens 10 and the radiation source 20, and the ToF emission module reduces the volume while ensuring the efficiency of the outgoing light.

[0058] 3 and 4 , further, the radial period 121 of the superstructure units 12 in the second region 102 is correspondingly smaller than the radial period 121 of the superstructure units 12 in the first region 101 , and / or the circumferential period 122 of the superstructure units 12 in the second region 102 is correspondingly smaller than the circumferential period 122 of the superstructure units 12 in the first region 101 .

[0059] In this embodiment, the period value of the super-structure unit 12 specifically refers to: the radial period and / or the circumferential period of the super-structure unit 12 .

[0060] Of course, in an embodiment not shown, the period value of the superstructure unit 12 may also be a period in the X-axis and / or Y-axis directions.

[0061] Specifically, the radial period 121 and the circumferential period 122 of the superstructure units 12 in the second region 102 are both smaller than the radial period 121 and the circumferential period 122 of the superstructure units 12 in the first region 101. Alternatively, the radial period 121 of the superstructure units 12 in the second region 102 is smaller than the radial period 121 of the superstructure units 12 in the first region 101, and the circumferential period 122 of the superstructure units 12 in the second region 102 is equal to the circumferential period 122 of the superstructure units 12 in the first region 101. Alternatively, the circumferential period 122 of the superstructure units 12 in the second region 102 is smaller than the circumferential period 122 of the superstructure units 12 in the first region 101, and the radial period 121 of the superstructure units 12 in the second region 102 is equal to the radial period 121 of the superstructure units 12 in the first region 101.

[0062] Specifically, different superstructure unit 12 periods are used in the first region 101 and the second region 102. These different superstructure unit 12 periods may be different in radial period 121 and / or circumferential period 122, that is, different in radial period 121, circumferential period 122, or both. The radial period 121 refers to the period value along the radius of an imaginary circle formed in the plane containing the X-axis and the Y-axis with center C as the center (as indicated by L1 in Figures 3 and 4). Similarly, the circumferential period 122 refers to the period value along the circumference of an imaginary circle formed in the plane containing the X-axis and the Y-axis with center C as the center (as indicated by L2 in Figures 3 and 4), or in other words, the period value along the central angle of the imaginary circle.

[0063] Preferably, the first region 101 is located at the center point C, and the second region 102 is located at the edge of the emitting metalens 10 away from the center point C. In this case, the incident light from the radiation source 20 irradiating the first region 101 is normal incidence or small angle incidence (for example, an incident angle of 0° to 5°), and the incident light from the radiation source 20 irradiating the second region 102 is large angle incidence (for example, an incident angle of 45° to 50°).

[0064] Preferably, after the multiple nanostructures 123 are arranged on the substrate 11, they are circular when viewed from a top view, that is, they are circular in the plane where the X-axis and the Y-axis are located. At this time, the first area 101 and the second area 102 are both closed circles, and the center of the first area 101 and the center of the second area 102 both coincide with the center C. The first area 101 is located at the center of the circle, and the second area 102 is located at the outer circle.

[0065] 3 , the present invention provides a top view and a partially enlarged schematic diagram of a preferred embodiment of an emitting metalens 10. Compared to a metalens with a constant period, this embodiment only changes the radial period 121.

[0066] Specifically, the radial period 121 of each superstructure unit 12 of the emitting metalens 10 decreases from the first region 101 to the second region 102, while the circumferential period 122 of each superstructure unit 12 of the emitting metalens 10 is equal. In this embodiment, the direction from the first region 101 to the second region 102 refers to the direction from the center of the circle (i.e., center C) to the outer circle. From the center of the circle (i.e., center C) to the outer circle, the radial period 121 of all superstructure units 12 on the emitting metalens 10 shows a decreasing trend, while the circumferential period 122 of all superstructure units 12 remains unchanged. It can be seen that the entire emitting metalens 10 adopts a variable period solution. Therefore, compared to a metalens with a constant period, the nanostructures 123 of the emitting metalens 10 in this embodiment are denser along the radial direction of the first region 101 (i.e., direction L1 in the figure), achieving better modulation effect for incident light at large angles while having a relatively simple structure and low manufacturing difficulty.

[0067] In addition, in this embodiment, at the edge of the emitting superlens 10 , the centers of four adjacent nanostructures 123 form a rectangle, and as the distance from the center C increases, the aspect ratio of the rectangle increases.

[0068] In an embodiment not shown, the circumferential period 122 of all superstructure units 12 on the emitting metalens 10 may decrease in the direction from the center of the circle (i.e., the center C) to the outer circle, while the radial period 121 of all superstructure units 12 remains unchanged, which can also achieve a better modulation effect for incident light at a large angle.

[0069] As shown in Figure 4 , the present invention provides a top view and a partially enlarged schematic diagram of another preferred embodiment of the emitting metalens 10. Compared with the above embodiment, this embodiment changes both the radial period 121 and the circumferential period 122.

[0070] Specifically, the radial period 121 and circumferential period 122 of each superstructure unit 12 of the emitting metalens 10 decrease in the direction from the first region 101 to the second region 102. In this embodiment, the direction from the first region 101 to the second region 102 refers to the direction from the center of the circle (i.e., center C) to the outer circle. From the center of the circle (i.e., center C) to the outer circle, the radial period 121 and circumferential period 122 of all superstructure units 12 on the emitting metalens 10 show a decreasing trend. It can be seen that the entire emitting metalens 10 adopts a variable period solution. Therefore, compared to the metalens in the above-mentioned embodiment, the nanostructures 123 of the emitting metalens 10 in this embodiment are denser in the radial and circumferential directions along the first region 101, and have a better modulation effect on incident light at large angles.

[0071] In addition, in this embodiment, at the edge of the emitting superlens 10 , the centers of four adjacent nanostructures 123 form a square.

[0072] 5 , the emitting metalens 10 further includes a third region 103 in which the superstructure units 12 are arranged. The centers of the first, third, and second regions 101, 103, and 102 coincide with each other, and their outer diameters increase in sequence. In this embodiment, the third region 103 is located between the first and second regions 101, 102. The centers of the three regions coincide with the center C, and the three regions do not overlap with each other. As shown in FIG2 , the third region 103 is preferably disposed adjacent to the first and second regions 101, 102. Thus, the emitting metalens 10 is arranged in order from the center (i.e., the center C) to the outer circumference of the first, third, and second regions 101, 103, and 102.

[0073] Of course, in an embodiment not shown, the third area 103 may be spaced apart from the first area 101 and the second area 102. Alternatively, the first area 101, the third area 103 and the second area 102 may all be in an open ring shape.

[0074] Specifically, the radial period 121 and / or the circumferential period 122 of the superstructure units 12 in the third region 103 decreases from the first region 101 to the second region 102 .

[0075] In this embodiment, when the third region 103 is disposed adjacent to the first region 101 and the second region 102, the periodicity (including the radial period 121 and / or the circumferential period 122) of the superstructure unit 12 in the third region 103 decreases from the center of the circle (i.e., the center C) toward the outer circle. Therefore, all superstructure units 12 in the region between the first region 101 and the second region 102 adopt a variable period scheme, while the region outside the first region 101 and the second region 102 can adopt a constant period or a variable period scheme, thereby achieving a better modulation effect for incident light at different angles between the first region 101 and the second region 102.

[0076] When the third region 103 is spaced apart from the first region 101 and the second region 102, for example, one or more regions are spaced between the first region 101 and the second region 102, the radial period 121 and / or circumferential period 122 of the superstructure units 12 in the third region 103 decreases from the center (i.e., center C) to the outer circle. That is, from the center (i.e., center C) to the outer circle, the radial period 121 and / or circumferential period 122 of the superstructure units 12 in at least one of the multiple regions between the first region 101 and the second region 102 decreases, while the period of the superstructure units 12 in the other regions remains constant.

[0077] The above two methods enable at least a portion of the emitting metalens 10 to adopt a variable period solution, while the remaining regions can adopt a constant period solution.

[0078] Of course, in an embodiment not shown, the period (including the radial period 121 and / or the circumferential period 122 ) of the superstructure units 12 in the third region 103 may also be a constant period.

[0079] Furthermore, the radial period 121 and circumferential period 122 of the superstructure units 12 in the first region 101 and / or the second region 102 remain unchanged. In this embodiment, the superstructure units 12 in the first region 101 have a constant period, while the superstructure units 12 in the second region 102 have a variable period. Alternatively, the superstructure units 12 in the first region 101 have a variable period, while the superstructure units 12 in the second region 102 have a constant period. Alternatively, the superstructure units in both the first region 101 and the second region 102 have a constant period.

[0080] Because the incident light from the radiation source 20 on the first region 101 is normal incidence or incident at a low angle, the use of a variable period for the superstructure units 12 in this region has little impact on the modulation effect. Similarly, the incident light from the radiation source 20 on the second region 102 is incident at a high angle, so the use of a variable period for the superstructure units 12 in this region has little impact on the modulation effect, and the edges of the second region 102 cannot accommodate more nanostructures 123. Therefore, using a constant period (including the radial period 121 and the circumferential period 122) within the first region 101 and / or the second region 102 can reduce the manufacturing difficulty of the emitting metalens 10 and minimize the impact on the metalens efficiency.

[0081] Furthermore, the radial period 121 and / or circumferential period 122 of the superstructure units 12 in the third region 103 decreases proportionally from the first region 101 to the second region 102. In this embodiment, the period (including the radial period 121 and / or circumferential period 122) of the superstructure units 12 in the third region 103 is correspondingly smaller than that of the superstructure units 12 in the first region 101 and correspondingly larger than that of the superstructure units 12 in the second region 102. The proportional change in the period of the superstructure units 12 in the third region 103 eliminates the need to determine the period value corresponding to all incident angles in the third region 103, facilitating the fabrication of the emitting metalens 10.

[0082] Specifically, by obtaining the incident angle and period value corresponding to the first region 101 and the second region 102 or their average value (for example, when there are multiple incident angles in the first region 101 or the second region 102), a first linear function is established between the incident angle and the period value. The period and incident angle of the superstructure unit 12 in the third region 103 can be obtained by substituting the first linear function into the first linear function, thereby simplifying the design and manufacturing process of the emitting metalens 10.

[0083] Of course, in some embodiments, other functions, such as a quadratic function, may be established according to the incident angles and period values ​​corresponding to the first region 101 and the second region 102 .

[0084] Furthermore, the third region 103 includes a first region 1031, a second region 1032, and a third region 1033, each having an outer diameter that increases in sequence. In this embodiment, as shown in FIG2 , the third region 103 is further divided into a first region 1031, a second region 1032, and a third region 1033, each having its center coincident with the other. The incident angles of the outgoing beam from the radiation source 20 on the three regions are different. For example, the incident angle on the first region 1031 is between 5° and 15°, the incident angle on the second region 1032 is between 15° and 30°, and the incident angle on the third region 1033 is between 30° and 45°.

[0085] Specifically, the radial period 121 and / or circumferential period 122 of the superstructure units 12 in the first region 1031 decreases proportionally from the first region 101 to the second region 1032. In this embodiment, by obtaining the incident angle and period values ​​corresponding to the first region 101 and the second region 1032, or their average value (for example, when there are multiple incident angles in the first region 101 or the second region 1032), a second linear function is established between the incident angle and the period value. Substituting the period and incident angle of the superstructure units 12 in the first region 1031 into the second linear function can be obtained. This eliminates the need to obtain the period values ​​corresponding to all incident angles in the first region 1031, thereby facilitating the manufacture of the emitting metalens 10.

[0086] Specifically, the radial period 121 and / or circumferential period 122 of the superstructure units 12 in the second region 1032 decreases proportionally from the first region 1031 to the third region 1033. In this embodiment, by obtaining the incident angle and period values ​​corresponding to the first region 1031 and the third region 1033, or their average value (for example, when there are multiple incident angles in the first region 1031 or the third region 1033), a third linear function is established between the incident angle and the period value. Substituting the period and incident angle of the superstructure units 12 in the second region 1032 into the third linear function can be obtained. This eliminates the need to obtain the period values ​​corresponding to all incident angles in the second region 1032, thereby facilitating the manufacture of the emitting metalens 10.

[0087] Specifically, the radial period 121 and / or circumferential period 122 of the superstructure units 12 in the third region 1033 decreases proportionally from the second region 1032 to the second region 102. In this embodiment, by obtaining the incident angle and period values ​​corresponding to the second region 1032 and the second region 102, or their average value (for example, when there are multiple incident angles in the second region 1032 or the second region 102), a fourth linear function is established between the incident angle and the period value. Substituting the period and incident angle of the superstructure units 12 in the third region 1033 into the fourth linear function can be obtained. This eliminates the need to obtain the period values ​​corresponding to all incident angles in the third region 1033, thereby facilitating the manufacture of the emitting metalens 10.

[0088] Therefore, the third region 103 is further divided into regions, and the linear functions corresponding to each region are calculated to more accurately arrange the superstructure units 12, thereby achieving a better modulation effect generated by the periodicity of the superstructure units 12 in the third region 103 and improving the overall efficiency of the emitting metalens 10.

[0089] Of course, in other embodiments, the third area 103 may be divided into other numbers of zones, such as two zones, four zones, five zones, etc.

[0090] As shown in Figures 5 and 6, an emitting superlens 10 provided in a preferred embodiment of the present invention is provided with an anti-reflection film 13. The anti-reflection film 13 is made of a single material, which reduces the reflectivity of the emitting superlens 10 while improving the transmittance of the emitting superlens 10, saving manufacturing costs.

[0091] The antireflection film 13 may also be referred to as an AR antireflection film. The antireflection film 13 is deposited on the emitting metalens 10 by processes such as electron beam evaporation, chemical vapor deposition, magnetron sputtering, and atomic layer deposition. The material of the antireflection film 13 may be any combination of silicon dioxide, titanium oxide, tantalum oxide, hafnium oxide, silicon nitride, aluminum oxide, polycrystalline silicon, gallium nitride, crystalline germanium, selenium sulfide, or selenium sulfide to form alternating layers.

[0092] Specifically, as shown in FIG6 , the emitting metalens 10 further includes at least one antireflection film 13 disposed on the substrate 11 and / or the filler, with the antireflection film 13 being disposed at least between the nanostructures 123 of the emitting metalens 10 and the substrate 11. In this embodiment, the structure in which the emitting metalens 10 is provided with at least one antireflection film 13 includes the four cases shown in FIG6 (corresponding to A-1, A-2, A-3, and A-4 in the figure, respectively). It is sufficient as long as there is a layer of antireflection film 13 between the nanostructures 123 of the emitting metalens 10 and the substrate 11.

[0093] Specifically, the emitting superlens 10 further includes a filler 14 connecting the nanostructure 123 and the substrate 11. In this embodiment, the filler 14 is used to protect the nanostructure 123 and can be air, i.e., unprotected, or a polymer material, etc. As shown in A-1 of FIG6 , an anti-reflection film 13 is provided between the nanostructure 123 of the emitting superlens 10 and the substrate 11. As shown in A-2 of FIG6 , an anti-reflection film 13 is provided between the nanostructure 123 of the emitting superlens 10 and the substrate 11, and an anti-reflection film 13 is also provided on the light incident side of the emitting superlens 10 as shown in FIG5 . As shown in A-3 of FIG6 , an anti-reflection film 13 is provided between the nanostructure 123 of the emitting superlens 10 and the substrate 11, and an anti-reflection film 13 is also provided on the light exiting side of the emitting superlens 10 as shown in FIG5 . As shown in A-4 in FIG6 , an antireflection film 13 is provided between the nanostructure 123 of the emitting superlens 10 and the substrate 11 , and an antireflection film 13 is provided on both the light incident side and the light emitting side of the emitting superlens 10 as shown in FIG5 .

[0094] As shown in Figures 5 and 7, the emitting superlens 10 provided in another preferred embodiment of the present invention, compared with the above embodiment, the anti-reflection film 13 uses multiple materials, or at least two materials, which reduces the reflectivity of the emitting superlens 10 while improving the transmittance of the emitting superlens 10.

[0095] Likewise, the antireflection film 13 in this embodiment is also applicable to the four cases in the above embodiments (corresponding to A-1, A-2, A-3, and A-4 in FIG6 , respectively).

[0096] Specifically, the emitting metalens 10 further includes an antireflection film 13 provided on the substrate 11 and / or the filler 14. In this embodiment, it is preferred that the antireflection film 13 is provided on both the substrate 11 and the filler 14. At this time, one layer of antireflection film 13 covers the surface of the filler 14 on the side away from the substrate 11, and another layer of antireflection film 13 covers the surface of the substrate 11 on the side away from the nanostructure 123. That is, as shown in FIG5 , both the light incident side and the light exiting side of the emitting metalens 10 are covered with an antireflection film 13. By providing the antireflection film 13, the reflectivity can be reduced, thereby increasing the transmittance of the metalens and further improving the efficiency of the metalens.

[0097] Specifically, the antireflection film 13 includes a first material layer 131 and a second material layer 132. In this embodiment, the first material layer 131 is preferably silicon nitride, and the second material layer 132 is preferably silicon oxide, so as to meet the high transmittance condition when the light beam is incident at a large angle.

[0098] Specifically, the first material layer 131 or the second material layer 132 is connected to the emitting superlens 10. In this embodiment, different material layers are selected to connect the substrate 11 and the filler 14, depending on the materials used. For example, as shown in Figure 7, when both the substrate 11 and the filler 14 are made of silicon oxide, the first material layer 131 (i.e., silicon nitride) is connected to the substrate 11 and the filler 14, while the second material layer 132 is connected to the outside of the first material layer 131. Similarly, when the substrate 11 and the filler 14 are made of other materials, the second material layer 132 can also be connected to the substrate 11 and the filler 14.

[0099] 8 and 9 , according to another aspect of the present invention, a ToF system is provided, which is provided with a ToF transmitting module according to the present invention and a ToF receiving module corresponding to the ToF transmitting module, and the ToF receiving module includes a receiving lens.

[0100] In this embodiment, the ToF receiving module also includes a detector 31, and the receiving lens is arranged on the light incident side of the detector 31 and corresponds to the detector 31. Thus, when the ToF system is working, when the outgoing light beam of the radiation source 20 passes through the emitting super lens 10, the emitting super lens 10 collimates the outgoing light beam and generates a point cloud, radiates it into the surrounding environment, and then produces a point cloud lighting pattern after being emitted to the target surface (i.e., the surface of the detection object). Since the point cloud emitted towards the obstacle in the radiation path of the point cloud can be reflected by the obstacle, the point cloud emitted towards the detection object is reflected back to the receiving lens by the detection object and forms an echo signal. The receiving lens focuses the echo signal on the detector, and the detector converts the echo signal from an optical signal to an electrical signal.

[0101] As shown in FIG8 , in a preferred embodiment of the present invention, a ToF system is provided, in which the receiving lens is configured as a receiving super lens 30 a , which can reduce the volume and weight of the ToF system.

[0102] Specifically, the receiving metalens 30a includes a plurality of array-arranged metastructure units, each of which is arranged aperiodically. In this embodiment, similar to the transmitting metalens 10, the receiving metalens 30a is also a metasurface, and the metastructure units on the receiving metalens 30a are arranged in the same aperiodic arrangement as the receiving metalens 30a. The specific arrangement can be found above and will not be further elaborated here.

[0103] As shown in FIG9 , in another preferred embodiment of the present invention, a ToF system is provided, in which the receiving lens is configured as a traditional lens combination 30 b , which can save the manufacturing cost of the ToF system.

[0104] It should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0105] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A ToF transmitting module, characterized in that: It includes a radiation source and an emitting super lens located on the light-emitting side of the radiation source, wherein the emitting super lens is used to modulate the outgoing light beam emitted by the radiation source to form a point cloud illumination pattern on the target surface, and the emitting super lens includes a plurality of super structure units arranged in an array, and the plurality of super structure units of the emitting super lens are arranged non-periodically.

2. The ToF transmitting module according to claim 1, characterized in that: The emitting superlens arranges superstructure units of different period values ​​correspondingly based on different incident angles of the radiation source.

3. The ToF transmitting module according to claim 1, characterized in that: The emitting superlens has a first region and a second region where superstructure units are arranged, the first region is closer to the center of the emitting superlens than the second region, and the period value of the superstructure units in the second region is smaller than the period value of the superstructure units in the first region.

4. The ToF transmitting module according to claim 3, characterized in that: The radial period of the superstructure units in the second region is correspondingly smaller than the radial period of the superstructure units in the first region, and / or the circumferential period of the superstructure units in the second region is correspondingly smaller than the circumferential period of the superstructure units in the first region.

5. The ToF transmitting module according to claim 4, characterized in that: The radial period of each superstructure unit of the emitting superlens decreases from the first region to the second region, and the circumferential period of each superstructure unit of the emitting superlens is equal.

6. The ToF transmitting module according to claim 4, characterized in that: The radial period and the circumferential period of each superstructure unit of the emitting superlens decrease from the first area to the second area.

7. The ToF transmitting module according to claim 4, characterized in that: The emitting metalens also has a third area where superstructure units are arranged, the centers of the first area, the third area and the second area coincide with each other, and the outer diameters increase successively, and the radial period and / or circumferential period of the superstructure units in the third area decreases from the first area to the second area.

8. The ToF transmitting module according to claim 7, characterized in that: The radial period and the circumferential period of the superstructure units in the first region and / or the second region remain unchanged.

9. The ToF transmitting module according to claim 7, characterized in that: The radial period and / or circumferential period of the superstructure units in the third region decreases proportionally from the first region to the second region.

10. The ToF transmitting module according to claim 1, characterized in that: The emitting superlens is configured as a transmissive superlens or a reflective superlens.

11. The ToF transmitting module according to claim 1, characterized in that: A nanostructure is provided at the center and / or vertex of each superstructure unit of the emitting superlens. Based on the phase distribution of the nanostructure, the emitting superlens collimates and diffracts the outgoing light beam.

12. The ToF transmitting module according to claim 11, characterized in that: The emitting superlens also includes a substrate connected to the nanostructure, a filler connecting the nanostructure and the substrate, and at least one anti-reflection film arranged on the substrate and / or the filler.

13. The ToF transmitting module according to claim 12, characterized in that: An antireflection film is provided at least between the nanostructure of the emitting superlens and the substrate.

14. The ToF transmitting module according to claim 11, characterized in that: The emitting superlens also includes a substrate connected to the nanostructure, a filler connecting the nanostructure and the substrate, and an anti-reflection film arranged on the substrate and / or the filler, wherein the anti-reflection film includes a first material layer and a second material layer, and the first material layer or the second material layer is connected to the emitting superlens.

15. A ToF system, characterized in that: It comprises a ToF transmitting module as described in any one of claims 1-12 and a ToF receiving module corresponding to the ToF transmitting module, wherein the ToF receiving module comprises a receiving lens, and the receiving lens is configured as a receiving super lens or a traditional lens combination.

16. The ToF system according to claim 15, wherein: The receiving super lens includes a plurality of super structure units arranged in an array, and the plurality of super structure units of the receiving super lens are arranged non-periodically.

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