A dual-spectrum metasurface, point cloud generating device and laser radar transmitting system

Abstract

The present invention provides a dual-spectrum metasurface, a dual-spectrum collimation-point cloud / multi-line generating device and a laser radar transmitting system including the same. The dual-spectrum metasurface is arranged on the same surface, including a plurality of metasurface structural units arranged in an array, and a nanostructure is respectively arranged at the center position of each of the metasurface structural units, or at the center position and the vertex position of each of the metasurface structural units; the metasurface structural units can efficiently transmit light of different wavelengths, and the light of different wavelengths includes near-infrared light 930-950nm and near-infrared light 1530-1570nm. The dual-spectrum collimation-point cloud / multi-line generating device and the laser radar transmitting system integrate the collimation system and the diffractive optical element, including the point cloud and multi-line generating devices, into a single device, and have the advantages of simple structure, light weight, small size and easy integration.

Description

Technical Field

[0001] The present invention relates to the field of metasurface devices, and in particular to a dual-spectrum metasurface, a dual-spectrum collimation-point cloud / multi-line generation device and a laser radar emission system. Background Art

[0002] As a basic component in scientific and industrial fields such as autonomous driving, precision modeling, and 3D remote sensing, LiDAR plays a vital role. Traditional LiDAR transmission systems are composed of single-wavelength lasers, collimating lenses, and diffractive optical elements (for generating point clouds). However, traditional LiDAR transmission systems have shortcomings such as large size, heavy weight, complex structure, and inability to distinguish the material of objects. Summary of the invention

[0003] In response to the above technical problems, embodiments of the present invention provide a dual-spectrum metasurface, a dual-spectrum collimation-point cloud / multi-line generation device and a laser radar transmission system comprising the same.

[0004] A first aspect of an embodiment of the present invention provides a dual-spectrum metasurface, which is arranged on the same surface and includes a plurality of metasurface structure units arranged in an array, wherein a nanostructure is respectively arranged at the center position of each of the metasurface structure units, or at the center position and the vertex position of each of the metasurface structure units; the metasurface structure units can efficiently transmit light of different wavelengths, and the light of different wavelengths includes near-infrared light of 930-950nm and near-infrared light of 1530-1570nm.

[0005] Optionally, the supersurface structural unit is a regular hexagon and / or a square;

[0006] When the incident light is polarized light or unpolarized light, the nanostructure on the dual-spectrum metasurface is axially symmetric along a first axis and a second axis, respectively, and a plurality of nanostructure units obtained by dividing the nanostructure along the first axis and the second axis are the same, wherein the first axis is perpendicular to the second axis, and the first axis and the second axis are perpendicular to the height direction of the nanostructure, respectively; and the nanostructures at different positions have different optical phases at different wavelengths.

[0007] A second aspect of an embodiment of the present invention provides a dual-spectrum collimation-point cloud / multi-line generation device, comprising:

[0008] The substrate has high transmittance in both spectra;

[0009] The dual-spectrum metasurface as described in any of the above items is arranged on both sides of the substrate, wherein the side close to the light source is a collimating metasurface, which is used for the divergent light velocity of the laser light source; and the side far away from the light source is a point cloud / multi-line generating metasurface, which is used to generate point cloud / multi-line in the far field.

[0010] Optionally, the substrate is quartz glass, Schott glass or crown glass, and the thickness of the substrate is 0.1 mm to 10 mm.

[0011] Optionally, the phase of the collimating metasurface satisfies:

[0012]

[0013] in, is the phase distribution of the collimating metasurface to the first near-infrared light, r is the position of the collimating metasurface along the radial direction, λ1 is in the near-infrared light of 930-950nm, and f1 is the focal length of the collimating metasurface to the first near-infrared light; is the phase distribution of the collimating metasurface to the second near-infrared light, r is the position of the collimating metasurface along the radial direction, λ2 is in the near-infrared light 1530-1570nm, and f2 is the focal length of the collimating metasurface to the second near-infrared light.

[0014] Optionally, the phase distribution of the point cloud / multi-line generated metasurface is determined by the far-field point cloud / multi-line distribution, and this phase distribution can be calculated by the Gerchberg-Saxton iterative algorithm.

[0015] The dual-spectrum collimation-point cloud / multi-line generating device of the present invention integrates the collimation system and the diffractive optical element (point cloud / multi-line generating device) into a single device, which has a simple structure, light weight, small size and is easy to integrate.

[0016] A third aspect of an embodiment of the present invention provides a laser radar transmission system, comprising: two lasers, with central wavelengths at 940 nm and 1550 nm respectively;

[0017] a dichroic mirror;

[0018] A scanning system;

[0019] And a dual spectrum collimation-point cloud / multi-line generator as described in any one of the above.

[0020] Optionally, the light source of the laser is a point light source, and the divergence angle after collimation is 1 mrad to 5 mrad; or the light source of the laser is a surface light source, and the divergence angle after collimation is 1 mrad×1 mrad to 5 mrad×5 mrad.

[0021] Optionally, the number of points projected by the laser radar transmitting system in the far field is 100 to 1,000,000 points; the number of lines projected by the laser radar transmitting system in the far field is 16 to 1,024 lines.

[0022] Optionally, the scanning system is insensitive to the laser wavelength; the scanning system is a mechanical reflective scanning mirror or a MEMS reflective galvanometer.

[0023] It can be seen from the technical solutions provided by the above embodiments of the present invention that the laser radar transmitting system of the present invention integrates the collimation system and the diffraction optical element (point cloud / multi-line generating device) into a single device. Therefore, the laser radar transmitting system has the advantages of simple structure, light weight, small size and easy integration.

[0024] In addition, the laser radar transmitting system of the present invention has dual-spectrum transmission capability. Compared with the existing laser radar transmitting system, the optical system of the laser radar transmitting system of the present invention has the ability to detect different materials.

[0025] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A is a regular hexagonal arrangement diagram of a hypersurface in one embodiment of the present invention;

[0027] Figure 1B is a square arrangement diagram of a super surface in one embodiment of the present invention;

[0028] Figure 2A is a schematic diagram of a positive nanorod structure in one embodiment of the present invention;

[0029] Figure 2B is a schematic diagram of a negative nanorod structure in one embodiment of the present invention;

[0030] Figure 2C is a schematic diagram of a hollow nanocolumn structure in one embodiment of the present invention;

[0031] Figure 2D is a schematic diagram of a negative hollow nanocolumn structure in one embodiment of the present invention;

[0032] Figure 2E is a schematic diagram of a square nanorod structure in one embodiment of the present invention;

[0033] Figure 2F is a schematic diagram of a negative square nanorod structure in one embodiment of the present invention;

[0034] Figure 2G is a schematic diagram of a hollow square nanorod structure in one embodiment of the present invention;

[0035] Figure 2H is a schematic diagram of a negative hollow square nanorod structure in one embodiment of the present invention;

[0036] Fig.2Iis a schematic diagram of a topological nanocolumn structure in one embodiment of the present invention;

[0037] Figure 3A is a graph showing the relationship between the phase of light of a working wavelength of 940 nm and the diameter of a nanorod structure of a quartz substrate and amorphous silicon material in one embodiment of the present invention;

[0038] Figure 3B is a graph showing the relationship between the light transmittance at a working wavelength of 940 nm and the diameter of the nanorod structure of a quartz substrate and amorphous silicon material in one embodiment of the present invention;

[0039] Figure 3C is a graph showing the relationship between the phase of light at a working wavelength of 1550nm and the diameter of a nanorod structure of a quartz substrate and amorphous silicon material in one embodiment of the present invention;

[0040] Figure 3D FIG. 1 is a graph showing the relationship between the light transmittance at an operating wavelength of 1550 nm and the diameter of the nanorod structure of a quartz substrate and amorphous silicon material in one embodiment of the present invention.

[0041] Figure 4A It is a schematic diagram of the structure of a dual-spectrum collimation-point cloud / multi-line generation device in one embodiment of the present invention;

[0042] Figure 4B is a phase iteration calculation flow chart of a dual-spectrum collimation-point cloud / multi-line generation device in one embodiment of the present invention;

[0043] Figure 5A is a schematic diagram of a laser radar transmitting system in one embodiment of the present invention;

[0044] Figure 5B is a schematic diagram of a laser radar transmitting system in another embodiment of the present invention;

[0045] Fig. 6A yes Figure 5A , 5B A curve relationship diagram of the optical phase at 940nm and the metalens radius of the collimating metasurface of the dual-spectrum collimation-point cloud / multi-line generation device in the laser radar transmission system shown;

[0046] Figure 6B yes Figure 5A , 5B A curve relationship diagram of the optical phase at 1550nm and the metalens radius of the collimating metalens of the dual-spectrum collimation-point cloud / multi-line generation device in the laser radar transmission system shown;

[0047] Figure 6C yes Figure 5A , 5B The point cloud (576 points) of the dual-spectral collimation-point cloud / multi-line generation device in the transmission system shown produces a phase map of the metasurface;

[0048] Fig.6D yes Figure 5A , 5B The multi-line (64-line) phase map of the metasurface generated by the dual-spectral collimation-point cloud / multi-line generation device in the transmission system shown;

[0049] Figure 7 is a far-field point cloud image in a laser radar transmitting system in one embodiment of the present invention;

[0050] Figure 8 is a far-field multi-line diagram in a laser radar transmitting system in one embodiment of the present invention;

[0051] Reference numerals:

[0052] 100: dual-spectrum collimation-point cloud / multi-line generation device; 1: substrate; 11: collimation metasurface; 12: point cloud / multi-line generation metasurface;

[0053] 2: Supersurface structural unit; 21: Nanostructure; 211: Positive nanocolumn structure; 212: Negative nanocolumn structure; 2121: First column; 2122: First hollow part; 213: Hollow nanocolumn structure; 2131: Second cylinder; 2132: Second hollow part; 214: Negative hollow nanocolumn structure; 2141: Second column; 2412: Third hollow part; 2143: Third cylinder; 215: Square nanocolumn structure; 216: Negative square nanocolumn structure; 2161: Fourth column; 2162: Fourth hollow part; 217: Hollow square nanocolumn structure; 2171: Fifth column; 2172: Fifth hollow part; 218: Negative hollow square nanocolumn structure; 2181: Sixth column; 2182: Sixth hollow part; 2183: Seventh column; 219: Topological nanocolumn structure;

[0054] 31a, 31b: laser; 32: dichroic mirror; 33: scanning system DETAILED DESCRIPTION

[0055] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0056] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0057] It should be understood that although the terms first, second, third, etc. may be used to describe various information in the present invention, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at..." or "when..." or "in response to determination". In the absence of conflict, the features in the following embodiments and implementations may be combined with each other.

[0058] The single-wavelength laser radar transmission optical system composed of a collimating lens group and a diffractive optical element has the disadvantages of complex structure, heavy weight, large volume and difficult integration. In addition, the monochrome laser radar cannot distinguish the material of the detected object. At the same time, the diffraction efficiency of low-order diffractive optical elements is not high, which leads to a reduction in the detection distance of the laser radar.

[0059] Optical metasurfaces are rapidly emerging and becoming a mainstream way to achieve miniaturized and flat optics. Optical metasurfaces have demonstrated metasurface-based conical lenses, blazed gratings, polarizers, holographic dry plates, and flat lenses. Metasurfaces with continuous 2π phase changes make single-layer achromatic metalenses a reality. At the same time, achromatic metasurfaces are also used for white light imaging.

[0060] Embodiment 1:

[0061] The first aspect of the embodiment of the present invention provides a dual-spectrum metasurface, which is arranged on the same surface, including a plurality of metasurface structure units 2 arranged in an array, wherein a nanostructure 21 is respectively arranged at the center position of each of the metasurface structure units 2, or at the center position and the vertex position of each of the metasurface structure units 2; the metasurface structure unit 2 can efficiently transmit light of different wavelengths, and the light of different wavelengths includes near-infrared light 930-950nm and near-infrared light 1530-1570nm. The dual-spectrum metasurface can be specifically arranged on one side or both sides of the substrate 1.

[0062] Specifically, the metasurface structure unit 2 is a regular hexagon and / or a square; when the incident light is polarized light or unpolarized light, the nanostructure 21 on the dual-spectrum metasurface is axially symmetrical along a first axis and a second axis, respectively, and a plurality of nanostructure units obtained by cutting the nanostructure 21 along the first axis and the second axis are the same, wherein the first axis and the second axis are perpendicular, and the first axis and the second axis are perpendicular to the height direction of the nanostructure 21, respectively; the optical phases of the nanostructures 21 at different positions are different at different wavelengths.

[0063] For example, see Figure 1B , a nanostructure 21 is respectively arranged at the center of each metasurface structural unit. With such an array arrangement, the number of nanostructures 21 of the dual-spectrum metasurface formed is minimal, and the performance of the dual-spectrum metasurface formed also meets the requirements; for example, see Figure 1A A nanostructure 21 is respectively provided at the vertex position of each supersurface structure unit 2 and the center position of each supersurface structure unit.

[0064] For example, in some embodiments, see Figure 1A , all the metasurface structural units 2 are regular hexagons; in some other embodiments, see Figure 1B , all the supersurface structure units 2 are square; in some other embodiments, the multiple supersurface structure units 2 include regular hexagonal array units and square supersurface structure units 2. It should be understood that in other embodiments, the supersurface structure unit 2 can also be designed as other regular polygonal or fan-shaped structures.

[0065] In this embodiment, the nanostructure 21 has an average transmittance greater than 80% at 930-950 nm (central wavelength 940 nm) and 1530-1570 nm (central wavelength 1550 nm).

[0066] In this embodiment, the nanostructure 21 is axially symmetrical along the first axis and the second axis, and the multiple nanostructure units obtained by cutting the nanostructure 21 along the first axis and the second axis are the same, and this structure is insensitive to the polarization of the incident light. The first axis and the second axis are perpendicular, and the first axis and the second axis are perpendicular to the height direction of the nanostructure. It should be noted that the first axis and the second axis pass through the center of the nanostructure 21 and are parallel to the horizontal plane.

[0067] In this embodiment, the nanostructures 21 at different positions have different optical phases at different wavelengths to limit the optical phase distribution of the metasurface at different wavelengths. It should be noted that the overall structure formed by the multiple nanostructures 21 in the embodiment of the present application can simultaneously transmit dual-band near-infrared light.

[0068] Exemplarily, the material of the nanostructure 21 may be quartz glass, crystalline silicon or amorphous silicon; it should be understood that the material of the nanocolumn may also be other materials.

[0069] Exemplarily, the nanostructure 21 may be a nanocolumn structure, or other nanostructures that are axially symmetric along the horizontal axis and the vertical axis.

[0070] The following description will be made by taking the nanostructure 21 as a nanocolumn structure as an example; it should be understood that when the nanostructure 21 is other structures, the nanocolumn structure in the following embodiments can be replaced by a corresponding structure.

[0071] The nanocolumn structure may include at least one of a positive nanocolumn structure 211, a negative nanocolumn structure 212, a hollow nanocolumn structure 213, a negative hollow nanocolumn structure 214, a square nanocolumn structure 215, a negative square nanocolumn structure 216, a hollow square nanocolumn structure 217, a negative hollow square nanocolumn structure 218, and a topological nanocolumn structure 219. Exemplarily, the nanocolumn structure is one of the positive nanocolumn structure 211, the negative nanocolumn structure 212, the hollow nanocolumn structure 213, the negative hollow nanocolumn structure 214, the square nanocolumn structure 215, the negative square nanocolumn structure 216, the hollow square nanocolumn structure 217, the negative hollow square nanocolumn structure 218, and the topological nanocolumn structure 219, which is convenient for processing.

[0072] In the embodiment of the present application, the optical phase of the nanostructure is related to the height of the nanorod structure, the shape of the cross section and the material of the nanorod structure.

[0073] See also FIG. 2A to FIG. 2I , the height of the nanocolumn structure (ie, the height of the nanocolumn structure in the z direction) is H.

[0074] The height H of the nanopillar structure is greater than or equal to 300nm and less than or equal to 3500nm, the spacing between adjacent nanopillar structures (i.e., the spacing between the centers of two adjacent nanopillar structures) is greater than or equal to 40nm and less than or equal to 640nm, and the minimum size of the nanostructure and the minimum spacing between two adjacent nanopillar structures (i.e., the minimum distance between the edges of two adjacent nanopillars) may be 40nm. Exemplarily, the height H of the nanopillar structure is 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1100nm, 1200nm, 1300nm, 1400nm, 2500nm or 3500nm, etc. Exemplarily, the spacing between adjacent nanopillar structures is 40nm, 140nm, 240nm, 340nm, 440nm, 540nm or 640nm, etc.

[0075] See also Figure 2AThe positive nanorod structure 211 may include a first cylinder, which is a solid structure. The positive nanorod structure 211 has a cross-sectional diameter d in the xy plane, which ranges from 40nm to 600nm, such as d can be set to 40nm, 50nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 500nm, 600nm, etc.

[0076] See also Figure 2B , the negative nanocolumn structure 212 may include a first column 2121, the cross-sectional shape of the first column 2121 is the same as the shape of the supersurface structure unit 2, and illustratively, when the supersurface structure unit 2 is a hexagon, the cross-sectional shape of the first column 2121 is also a hexagon; when the supersurface structure unit 2 is a square, the cross-sectional shape of the first column 2121 is also a square. In this embodiment, the size of the cross-sectional size of the first column 2121 is the same as the size of the supersurface structure unit 2. The first column 2121 is provided with a cylindrical first hollow portion 2122 extending from the top to the bottom thereof, and the first column 2121 and the first hollow portion 2122 are coaxial. The negative nanorod structure 212 has a cross-sectional diameter d in the xy plane (ie, the cross section), which ranges from 40 nm to 600 nm. For example, d can be set to 40 nm, 50 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 500 nm, 600 nm, etc.

[0077] See also Figure 2C , the hollow nanocolumn structure 213 may include a second cylinder 2131, the second cylinder 2131 is provided with a cylindrical second hollow portion 2132 extending from the top to the bottom thereof, and the second cylinder 2131 is coaxial with the second hollow portion 2132. The hollow nanocolumn structure 213 has a cross-sectional outer diameter d1 and an inner diameter d2 in the xy plane, and the range of d1-d2 is between 40nm and 600nm, such as d1-d2 can be set to 40nm, 50nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 500nm, 600nm, etc.

[0078] See also Figure 2D, the negative hollow nanocolumn structure 214 may include a second column 2141, the cross-sectional shape of the second column 2141 is the same as the shape of the supersurface structure unit 2, and illustratively, when the supersurface structure unit 2 is a hexagon, the cross-sectional shape of the second column 2141 is also a hexagon; when the supersurface structure unit 2 is a square, the cross-sectional shape of the second column 2141 is also a square. In this embodiment, the size of the cross-sectional size of the second column 2141 is the same as the size of the supersurface structure unit 2. Further, the second column 2141 is provided with a cylindrical third hollow portion 2142 extending from the top to the bottom thereof. Further, a third cylinder 2143 is provided inside the third hollow portion 2142, and the third cylinder 2143 is a solid structure. The second column 2141 , the third hollow portion 2142 and the third cylinder 2143 are coaxial, and the second column 2141 and the third cylinder 2143 are of equal height. The bottom of the third cylinder 2143 is attached to the substrate 1 .

[0079] See also Figure 2E The square nanorod structure 215 may include a third column, the third column is a solid structure, and the cross-section of the third column is a square.

[0080] See also Figure 2F , the negative square nanorod structure 216 may include a fourth column 2161, the shape of the cross section of the fourth column 2161 is the same as the shape of the super surface structure unit 2, illustratively, when the super surface structure unit 2 is a hexagon, the shape of the cross section of the fourth column 2161 is also a hexagon; when the super surface structure unit 2 is a square, the shape of the cross section of the fourth column 2161 is also a square. In this embodiment, the size of the cross section of the fourth column 2161 is the same as the size of the super surface structure unit 2. Further, the fourth column 2161 is provided with a fourth hollow portion 2162 extending from the top to the bottom thereof, the shape of the cross section of the fourth hollow portion 2162 is a square, and the fourth column 2161 is coaxial with the fourth middle portion.

[0081] See also Figure 2G , the hollow square nanorod structure 217 may include a fifth column 2171, and the cross-section of the fifth column 2171 is in the shape of a square. Further, the fifth column 2171 is provided with a fifth hollow portion 2172 extending from the top to the bottom thereof, and the cross-section of the fifth hollow portion 2172 is in the shape of a square. Moreover, the fifth column 2171 is coaxial with the fifth hollow portion 2172. On the same cross-section, the corresponding diagonal lines of the square corresponding to the fifth column 2171 and the square corresponding to the fifth hollow portion 2172 are colinear.

[0082] See also Figure 2H, the negative hollow square nanocolumn structure 218 may include a sixth column 2181, the shape of the cross section of the sixth column 2181 is the same as the shape of the super surface structure unit 2, illustratively, when the super surface structure unit 2 is a hexagon, the shape of the cross section of the sixth column 2181 is also a hexagon; when the super surface structure unit 2 is a square, the shape of the cross section of the sixth column 2181 is also a square. In this embodiment, the size of the cross section of the sixth column 2181 is the same as the size of the super surface structure unit 2. Further, the sixth column 2181 is provided with a sixth hollow portion 2182 extending from its top to the bottom, and the shape of the cross section of the sixth hollow portion 2182 is a square. A seventh column 2183 is provided inside the sixth hollow portion 2182, and the seventh column 2183 is a solid structure, and the shape of the cross section of the seventh column 2183 is a square. In this embodiment, the sixth column 2181, the sixth hollow portion 2182 and the seventh column 2183 are coaxial. Furthermore, on the same cross section, the diagonal lines corresponding to the square corresponding to the seventh column 2183 and the diagonal lines corresponding to the square corresponding to the sixth hollow portion 2182 are collinear.

[0083] See also Fig.2I The topological nano-column structure 219 may include an eighth column, which is a solid structure, and a cross section of the eighth column is a polygon, and the sides of the polygon are arc-shaped.

[0084] For example, in some embodiments, the nanocolumn structure is a round nanocolumn structure. For designs working at a near-infrared wavelength of 940 nm, the round nanocolumn structure is made of amorphous silicon, and the positive nanocolumn structure is made of Figure 2A The positive nanocolumn structure shown has a height H of 1600 nm, and the side of the corresponding regular hexagonal basic unit is 405 nm. Figure 3A The relationship between the optical phase of the metasurface and the diameter of the positive nanopillar structure at a near-infrared wavelength of 940nm is given. Figure 3A In the figure, the horizontal axis is the diameter of the positive nanorod structure, and the vertical axis is the light phase at 940 nm. Figure 3B The relationship between the transmittance of the metasurface and the diameter of the positive nanopillar structure at a near-infrared wavelength of 940nm is given. Figure 3B In the figure, the horizontal axis is the diameter of the positive nanorod structure, and the vertical axis is the light phase at 940 nm. Figure 3C The relationship between the optical phase of the metasurface and the diameter of the positive nanopillar structure at a near-infrared wavelength of 1550nm is given. Figure 3C In the figure, the horizontal axis is the diameter of the positive nanorod structure, and the vertical axis is the light phase at 1550nm. Figure 3D The relationship between the transmittance of the metasurface and the diameter of the positive nanopillar structure at a near-infrared wavelength of 1550nm is given. Figure 3D In the figure, the horizontal axis is the diameter of the positive nanorod structure, and the vertical axis is the light phase at 1550nm.

[0085] Embodiment 2:

[0086] A second aspect of the present invention provides a dual-spectrum collimation-point cloud / multi-line generation device 100, please refer to Figure 4A The dual-spectrum collimation-point cloud / multi-line generating device includes: a substrate 1, which has high transmittance in two spectra; a dual-spectrum metasurface as described in any one of the above items, which is arranged on both sides of the substrate 1, wherein the side close to the light source is a collimation metasurface 11, which is used for the divergent light speed of the laser light source; wherein the side far away from the light source is a point cloud / multi-line generating metasurface 12, which is used to generate point cloud / multi-line in the far field, and has the same function as the diffraction optical element in the traditional lidar.

[0087] Optionally, the substrate 1 is quartz glass or Schott glass or crown glass, and the thickness of the substrate 1 is 0.1 mm to 10 mm. Exemplarily, the substrate material is a material with high transmittance of the first near-infrared light and the second near-infrared light, such as quartz glass, K9 glass, etc. The thickness of the substrate is between 0.1 mm and 10 mm, and the thickness can be set to 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.

[0088] Exemplarily, the phase of the collimating metasurface 11 satisfies:

[0089]

[0090] in, is the phase distribution of the collimating metasurface 11 to the first near-infrared light, r is the position of the collimating metasurface 11 along the radial direction, λ1 is in the near-infrared light of 930-950nm, and f1 is the focal length of the collimating metasurface 11 to the first near-infrared light; is the phase distribution of the collimating metasurface 11 to the second near-infrared light, r is the position of the collimating metasurface 11 along the radial direction, λ2 is in the near-infrared light 1530-1570nm, and f2 is the focal length of the collimating metasurface 11 to the second near-infrared light.

[0091] The phase distribution of the point cloud / multi-line generated metasurface 12 is determined by the far-field point cloud / multi-line distribution, and this phase distribution can be calculated by the Gerchberg-Saxton iterative algorithm.

[0092] The dual-spectrum collimation-point cloud / multi-line generating device of the present invention integrates the collimation system and the diffractive optical element (point cloud / multi-line generating device) into a single device, which has a simple structure, light weight, small size and is easy to integrate.

[0093] Embodiment three:

[0094] A third aspect of an embodiment of the present invention provides a laser radar transmitting system, including:

[0095] Two lasers 31a and 31b, with central wavelengths at 940nm and 1550nm respectively;

[0096] a dichroic mirror 32;

[0097] a scanning system 33;

[0098] And a dual-spectrum collimation-point cloud / multi-line generating device 100 as described in any one of the above.

[0099] The laser radar transmitting system of the present invention uses a dual-spectrum collimation-point cloud / multi-line generating device 100. Compared with the existing laser radar transmitting system, the dual-spectrum laser radar transmitting system of the present invention has a simple structure, small size, light weight, easy integration and can distinguish the material of the detected object.

[0100] Optionally, the light sources of the lasers 31a and 31b may be point light sources, and the divergence angles after collimation are 1 mrad to 5 mrad; or the light sources of the lasers 31a and 31b may be surface light sources, and the divergence angles after collimation are 1 mrad×1 mrad to 5 mrad×5 mrad.

[0101] Optionally, the number of points projected by the laser radar transmitting system in the far field is 100 to 1,000,000 points; the number of lines projected by the laser radar transmitting system in the far field is 16 to 1,024 lines.

[0102] Specifically, the scanning system 33 is insensitive to the laser wavelength; the scanning system 33 may be a mechanical reflective scanning mirror or a MEMS reflective galvanometer.

[0103] For example, please refer to Figure 5A and 5B ,in Figure 5A is a schematic diagram of a laser radar transmitting system when the scanning system 33 is a mechanical reflective scanning mirror, Figure 5B It is a schematic diagram of a laser radar transmitting system when the scanning system 33 is a MEMS reflective galvanometer.

[0104] For example, the 940nm lasers are all vertical cavity surface emitting lasers, the light emitting area is a circle with a diameter of 0.36mm, and the divergence angle is 24°; on the other hand, the 1550nm lasers are all vertical cavity surface emitting lasers, the light emitting area is a circle with a diameter of 0.36mm, and the divergence angle is 24°. The focal length of the collimating metasurface 11 for both 940nm and 1550nm is 120mm, and the diameter of the collimating metasurface 11 is 50.8mm (2 inches). The phase distribution of the collimating metasurface can be calculated according to formula (1). The phase distribution of 940nm and 1550nm refers to Fig. 6A and Figure 6B , where the solid line is the phase required for theoretical calculation, and the "*" is the phase of the light emitted by the nanostructure at 940nm and 1550nm respectively by searching the nano database. The material of substrate 1 is quartz glass with a thickness of 5mm. After collimation, the divergence angles of 940nm and 1550nm light are both 3mrad.

[0105] For example, refer to Figure 4B The process can obtain the required phase diagram of the far-field 576 point cloud through iterative Gerchberg-Saxton calculation, where: represents the Fourier transform, represents the inverse Fourier transform, I is the amplitude, is the phase, A is the complex amplitude; refer to Figure 6C , where the edge length of the hypersurface generated by the point cloud is 50.8 mm; on the other hand, referring to Figure 4B The process can obtain the required phase diagram of 64-line multi-line in the far field through iterative Gerchberg-Saxton calculation, refer to Fig.6D , where the side length of the multi-line generated metasurface is 50.8 mm.

[0106] For example, the 576-point cloud image formed by 940nm and 1550nm in the far field is shown in Figure 2. Figure 7 .

[0107] For example, the 64-line diagram formed by 940nm and 1550nm in the far field is shown in FIG. Figure 8 .

[0108] Exemplarily, when the scanning system 33 is a mechanical reflective scanning mirror, specifically a dual-axis mechanical scanning field mirror, the scanning angle is 40°×10°, and the scanning frequency is 40 Hz; on the other hand, when the scanning system 33 is a MEMS reflective galvanometer, specifically a dual-axis MEMS reflective galvanometer, the scanning angle is 30°×24°, the fast-axis scanning frequency is 25 kHz, and the slow-axis scanning frequency is 1.2 kHz.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-spectrum collimation-point cloud / multi-line generation device, characterized in that: include: The substrate has high transmittance in both spectra; A dual-spectrum metasurface is arranged on both sides of the substrate, wherein the side close to the light source is a collimating metasurface, which is used for the divergent beam of the laser light source; wherein the side far away from the light source is a point cloud / multi-line generating metasurface, which is used for generating point clouds / multi-lines in the far field; The dual-spectrum metasurface is arranged on the same surface, and includes a plurality of metasurface structural units arranged in an array, wherein a nanostructure is respectively arranged at the center position of each metasurface structural unit, or at the center position and the vertex position of each metasurface structural unit; the metasurface structural unit can efficiently transmit light of different wavelengths, and the light of different wavelengths includes near-infrared light of 930-950nm and near-infrared light of 1530-1570nm; The dual-spectrum metasurface is used in a laser radar transmitting system so that the laser radar transmitting system has the ability to detect different materials.

2. The dual-spectrum collimation-point cloud / multi-line generation device according to claim 1, characterized in that: The super surface structural unit is a regular hexagon and / or a square; When the incident light is polarized light or unpolarized light, the nanostructure on the dual-spectrum metasurface is axially symmetric along a first axis and a second axis, respectively, and a plurality of nanostructure units obtained by dividing the nanostructure along the first axis and the second axis are the same, wherein the first axis is perpendicular to the second axis, and the first axis and the second axis are perpendicular to the height direction of the nanostructure, respectively; and the nanostructures at different positions have different optical phases at different wavelengths.

3. The dual-spectrum collimation-point cloud / multi-line generation device according to claim 1, characterized in that: The substrate is quartz glass, Schott glass or crown glass, and the thickness of the substrate is 0.1 mm to 10 mm.

4. The dual-spectrum collimation-point cloud / multi-line generation device according to claim 1, characterized in that: The phase of the collimating metasurface satisfies: in, is the phase distribution of the collimating metasurface to the first near-infrared light, r is the position of the collimating metasurface along the radial direction, λ1 is in the near-infrared light of 930-950nm, and f1 is the focal length of the collimating metasurface to the first near-infrared light; is the phase distribution of the collimating metasurface to the second near-infrared light, r is the position of the collimating metasurface along the radial direction, λ2 is in the near-infrared light 1530-1570nm, and f2 is the focal length of the collimating metasurface to the second near-infrared light.

5. The dual-spectrum collimation-point cloud / multi-line generation device according to claim 1, characterized in that: The phase distribution of the point cloud / multi-line generated metasurface is determined by the far-field point cloud / multi-line distribution, and this phase distribution is calculated by the Gerchberg-Saxton iterative algorithm.

6. A laser radar transmitting system, characterized in that: include: Two lasers with central wavelengths at 940nm and 1550nm respectively; a dichroic mirror; a scanning system; and A dual spectrum collimation-point cloud / multi-line generation device as claimed in any one of claims 1 to 5.

7. The laser radar transmitting system according to claim 6, characterized in that: The laser light source is a point light source, and the divergence angle after collimation is 1mrad to 5mrad; or the laser light source is a surface light source, and the divergence angle after collimation is 1mrad×1mrad to 5mrad×5mrad.

8. The laser radar transmitting system according to claim 6, characterized in that: The number of points projected by the laser radar transmitting system in the far field is 100 to 1,000,000 points; the number of lines projected by the laser radar transmitting system in the far field is 16 to 1,024 lines.

9. The laser radar transmitting system according to claim 6, characterized in that: The scanning system is insensitive to the laser wavelength; the scanning system is a mechanical reflective scanning mirror or a MEMS reflective galvanometer.

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