A high-density structured light generating device

Abstract

This invention discloses a high-density structured light generation device, belonging to the technical field of structured light generation equipment. A metasurface device is integrated on the front end of a polarization-maintaining fiber. Light emitted from a light source is transmitted through the fiber to the metasurface device, and then the metasurface generates a structured light projection point cloud pattern at a predetermined location. The portion of the fiber extending into the imaging area has a diameter on par with the fiber diameter, making it smaller in size compared to traditional structured light projection systems that transmit light through free space. Furthermore, it can penetrate curved spaces to project structured light point clouds. The light-guiding fiber is a polarization-maintaining fiber, which can maintain the polarization characteristics of the beam during transmission. The metasurface microstructure used is a multi-channel multiplexed metasurface, which can modulate incident light of different wavelengths and polarizations, thereby simultaneously generating projection patterns from different channels at a predetermined location. By superimposing these patterns, the density of the projection point cloud is greatly increased, thus improving imaging accuracy in 3D imaging.

Description

Technical Field

[0001] This invention relates to the field of structured light generation equipment technology, and in particular to a high-density structured light generation device based on fiber end metasurface and capable of projecting high-density point clouds into a micro-cavity. Background Technology

[0002] Structured light 3D imaging technology is a type of 3D imaging technology based on active projection. Its principle involves projecting a pre-designed intensity pattern onto the target using a projection device, then capturing the pattern deformation caused by varying heights on the object's surface using a camera. Finally, high-precision 3D topographic information of the object is obtained through calculation. Traditional structured light 3D imaging systems are often bulky, limiting their application in fields such as medical procedures and industrial inspection. However, integrating the projection device into the fiber optic end face allows for the miniaturization of the entire system, enabling it to play a significant role in medical surgical applications and industrial non-destructive testing.

[0003] To obtain high-precision 3D topographic information, various pattern projection methods have been proposed. For example, Gray code and sinusoidal fringe coding require multiple frames of projection to capture the object's 3D information, while speckle structured light typically only requires a single image to calculate the object's 3D topographic information, offering better real-time performance and good imaging accuracy. However, current random point cloud methods still face the problem of a limited number of projected points, and this limited point cloud density also restricts the accuracy of 3D reconstruction.

[0004] To address this issue, larger-area devices can be used. Current speckle projection devices often employ diffractive optical elements (DOEs). While increasing the area of ​​the DOE can achieve higher density speckle patterns, this means the size of the optical system may be affected. Furthermore, DOEs suffer from low efficiency and a small field of view. Summary of the Invention

[0005] In view of the above problems, the present invention provides a high-density structured light generation device to overcome or at least partially solve the above problems. It solves the problem of low reconstruction resolution caused by the limited number of scattered points in current structured light projection systems used for 3D imaging in microcavities. This device can project high-density point cloud patterns from the end face of optical fibers at the millimeter or even sub-millimeter scale, and its application in 3D imaging systems can greatly improve the accuracy of 3D reconstruction.

[0006] This invention provides the following solution:

[0007] A high-density structured light generation device, comprising:

[0008] A light source assembly for generating at least two light sources of different wavelengths;

[0009] A switch box is connected to the light source assembly via an optical fiber patch cord; the switch box is used to control and couple at least two of the light sources.

[0010] A polarization-maintaining fiber, one end of which is connected to the switch box;

[0011] The polarization-maintaining fiber has a metasurface microstructure on its front end face; the polarization-maintaining fiber is used to transmit at least two light sources output from the switch box to the metasurface microstructure; the metasurface microstructure is used to modulate at least two light sources and form a target structured light distribution at a designated position, so as to improve the point cloud density of the formed structured light point cloud map by superimposing the point cloud patterns reconstructed by multiple wavelengths and multiple polarization channels.

[0012] Preferably, the light source assembly includes a laser light source, which includes a supercontinuum laser that simultaneously outputs multiple laser beams coaxially via an acousto-optic modulator or a combination of multiple single-wavelength lasers that simultaneously output multiple laser beams coaxially via a beam combiner.

[0013] Preferably, the laser includes a visible light laser or an infrared laser.

[0014] Preferably, the switch box includes at least one fiber optic multiplexer and at least two polarization controllers; the fiber optic multiplexer is used to couple at least two of the light sources to at least two of the polarization controllers or to couple the light sources output by at least two of the polarization controllers to the polarization-maintaining fiber; the polarization controllers are used to switch the polarization state of each of the light sources.

[0015] Preferably, the switch box further includes at least two optical switches, one end of each of the at least two optical switches is connected to the optical fiber jumper, and the other end of each of the at least two optical switches is connected to at least two polarization controllers respectively; the optical switches are used to control the on / off state of the light source coupled into the polarization-maintaining fiber.

[0016] Preferably, the polarization-maintaining fiber includes a single polarization-maintaining fiber or a bundle of fibers composed of multiple polarization-maintaining fibers.

[0017] Preferably, the connection method between the metasurface microstructure and the polarization-maintaining fiber includes either processing the front end face of the polarization-maintaining fiber using two-photon polymerization 3D printing technology, or preparing the metasurface microstructure using electron beam lithography and then pasting it onto the front end face of the polarization-maintaining fiber.

[0018] Preferably, the front end face of the polarization-maintaining fiber is connected to a beam expander; the metasurface microstructure is connected to the front end face of the beam expander; the beam expander is used to shape at least two light sources into target waveforms and target sizes and transmit them to the metasurface microstructure.

[0019] Preferably, the beam expander assembly includes any one of the following: coreless optical fiber, multiple microlenses, and hollow support.

[0020] Preferably, the metasurface microstructure includes superatoms and a substrate, and the geometry of the superatoms includes, but is not limited to, square prisms and cylindrical shapes.

[0021] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0022] This application provides a high-density structured light generation device that integrates a metasurface device on the front end of a polarization-maintaining fiber. Light emitted from a light source is transmitted through the fiber to the metasurface device, where it is then used to generate a structured light projection point cloud pattern at a predetermined location. The portion of the fiber extending into the imaging area has a diameter on par with the fiber diameter, making it smaller than traditional structured light projection systems that transmit light through free space. Furthermore, it can penetrate curved spaces to project structured light point clouds. The light-guiding fiber is a polarization-maintaining fiber, which preserves the polarization characteristics of the light beam during transmission. The metasurface microstructure used is a multi-channel multiplexed metasurface, which can modulate the incident light at different wavelengths and polarization channels, thereby simultaneously generating projection patterns from different channels at the predetermined location. By superimposing multiple projection patterns, the density of the projection point cloud is significantly increased, thereby improving imaging accuracy in 3D imaging.

[0023] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0025] Figure 1 This is a schematic diagram of a high-density structured light generation device provided in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a multi-wavelength coaxial output light source assembly provided in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of a light source assembly with multiple single-wavelength outputs provided in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the interior of the multi-wavelength coaxial output switch box assembly provided in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the interior of a switch box assembly with multiple single-wavelength outputs provided in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of a connection method using coreless optical fiber expansion provided in an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of a connection method for beam expansion using a microlens group provided in an embodiment of the present invention;

[0032] Figure 8 This is a schematic diagram of a connection method using a hollow support for beam expansion provided in an embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of the metasurface microstructure provided in an embodiment of the present invention;

[0034] Figure 10 These are structured light point cloud maps with different distribution states provided in embodiments of the present invention;

[0035] Figure 11 This is a schematic diagram of the process of generating structured light projection point clouds provided in an embodiment of the present invention.

[0036] In the diagram: 1. Light source assembly; 2. Switch box; 21. Fiber optic multiplexer; 22. Polarization controller; 23. Optical switch; 3. Fiber optic patch cord; 4. Polarization-maintaining fiber; 5. Metasurface microstructure; 51. Superatom; 52. Substrate; 6. Beam expander assembly; 61. Coreless fiber; 621. First microlens; 622. Second microlens; 63. Hollow support; 64. Structured light point cloud. Figure 7 First sparse projection pattern 71, second sparse projection pattern 72, third sparse projection pattern 73, fourth sparse projection pattern 74. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0038] See Figure 1 This invention provides a high-density structured light generation device, such as... Figure 1 As shown, the device may include:

[0039] Light source assembly 1, the light source assembly 1 being used to generate at least two light sources of different wavelengths;

[0040] Switch box 2 is connected to the light source assembly 1 via fiber optic patch cord 3; the switch box 2 is used to control and couple at least two of the light sources.

[0041] Polarization-maintaining fiber 4, one end of which is connected to the switch box 2;

[0042] The polarization-maintaining fiber 4 has a metasurface microstructure 5 on its front end. The polarization-maintaining fiber 4 transmits at least two paths of light from the light source output from the switch box 2 to the metasurface microstructure 5. The metasurface microstructure 5 modulates the at least two paths of light from the light source and forms a target structured light distribution at a designated location. This allows for the superposition of point cloud patterns reconstructed from multiple wavelengths and polarization channels, thereby improving the formation of the structured light point cloud. Figure 7 Point cloud density.

[0043] The high-density structured light generation device provided in this application adopts a metasurface microstructure 5 on the front end of the polarization-maintaining fiber 4, which avoids making the overall size of the device too large. The provided metasurface microstructure 5 can modulate light of different wavelengths and polarization states and form the desired structured light distribution at a specified position. By superimposing the point cloud patterns reconstructed from multiple wavelengths and polarization channels, the point cloud density of the structured light can be significantly improved. The size of the structured light generation area of ​​this device is only the diameter of the fiber. High-density structured light point clouds can be projected in a millimeter-scale area, which not only reduces the size of the 3D imaging device, but also greatly improves the accuracy of 3D imaging.

[0044] The metasurface microstructure device provided in this application is an artificially constructed device composed of subwavelength-scale microstructures, capable of flexibly controlling parameters such as amplitude, phase, and polarization of light waves in multiple dimensions. Its flexible and powerful optical field manipulation capabilities enable it to improve the efficiency and field-of-view issues of DOEs, and allow for simultaneous manipulation of multi-spectral and multi-polarization channel information. By spatially superimposing point clouds from different channels, a high-density structured light projection pattern is obtained.

[0045] The light source assembly 1 provided in this application embodiment is used to generate multiple light sources with different wavelengths or polarization states. In specific implementation, the specific type of light emitted by the light source can be determined as needed. For example, in one implementation, this application embodiment can provide that the light source assembly 1 includes a laser light source, which includes a supercontinuum laser that simultaneously outputs multiple laser beams coaxially via an acousto-optic modulator, or a combination of multiple single-wavelength lasers that simultaneously output multiple laser beams coaxially via a beam combiner. Further, the laser includes a visible light laser or an infrared laser.

[0046] Light source component 1 is a laser source capable of outputting multiple wavelengths. This source can be a supercontinuum laser that simultaneously outputs multiple laser beams coaxially via an acousto-optic modulator, or it can be multiple single-wavelength lasers combined together and simultaneously outputting multiple laser beams coaxially via a beam combiner, or multiple single-wavelength lasers that each simultaneously output a single laser beam to their respective fiber optic patch cords. The wavelength range of the laser can be selected from visible light lasers or infrared lasers according to design requirements.

[0047] Understandably, if a visible light band projection point cloud is required, a visible light band light source and optical fiber can be selected, and a metasurface can be designed for the required wavelengths; if an infrared band projection point cloud is required, an infrared band light source and optical fiber can be selected, and a metasurface can be designed for the required wavelengths.

[0048] The switch box 2 provided in this application embodiment is used to control and couple multiple light sources. In one implementation, the switch box 2 may include at least one fiber optic multiplexer 21 and at least two polarization controllers 22; the fiber optic multiplexer 21 is used to couple at least two light sources to at least two polarization controllers 22 or to couple the light sources output by at least two polarization controllers 22 to the polarization-maintaining fiber 4, and the polarization controllers 22 are used to switch the polarization state of each light source.

[0049] The switch box 2 contains an optical fiber multiplexer 21 and a polarization controller 22. The optical fiber multiplexer is used to couple multiple light sources into the polarization-maintaining fiber 4; the selection of the optical fiber multiplexer depends on the type of light source used. For light sources with coaxial output, a single optical fiber multiplexer is used to couple the light into the polarization-maintaining fiber 4; for light sources with non-coaxial output, multiple optical fiber multiplexers are used to couple the light into the polarization-maintaining fiber 4. The polarization controller 22 is used to switch the polarization state of each light source, such as switching the incident light to 0° and 90° polarization states, or left-handed and right-handed polarization states.

[0050] Furthermore, embodiments of this application may also provide that the switch box 2 further includes at least two optical switches 23, one end of each of the at least two optical switches 23 being connected to the optical fiber jumper 3, and the other end of each of the at least two optical switches 23 being connected to at least two polarization controllers 22 respectively; the optical switches 23 are used to control the on / off state of the light source coupled to the polarization-maintaining fiber 4. The optical switches 23 may be introduced depending on whether it is convenient to control the on / off state of the light source light of each wavelength.

[0051] The polarization-maintaining fiber 4 provided in this application embodiment is an important component for laser transmission. It is used to stably transmit a light beam with specific physical properties to the metasurface region at the fiber end without changing the physical properties of the beam, namely its polarization characteristics. Therefore, the polarization-maintaining fiber 4 must maintain the polarization state of the light beam while ensuring that light from multiple wavelengths does not leak out during transmission. In specific implementation, this application embodiment can provide that the polarization-maintaining fiber 4 includes a single polarization-maintaining fiber 4 or a bundle of fibers composed of multiple polarization-maintaining fibers 4.

[0052] Understandably, the polarization-maintaining fiber 4 needs to be selected with appropriate parameter types to ensure that the required orthogonal polarization state is maintained, while ensuring that the wavelength range covers the required operating wavelength. The numerical aperture of the polarization-maintaining fiber 4 also needs to be appropriate and needs to be matched with the beam expander components provided later.

[0053] The metasurface microstructure 5 provided in this embodiment is disposed at the front end of the polarization-maintaining fiber 4 without excessively increasing the volume of the polarization-maintaining fiber 4. It can modulate light from light sources of different wavelengths and polarization states and form the desired structured light distribution in the far field. The formed structured light can include point distribution, line distribution, and mesh distribution, as well as a combination of various shapes and patterns. When specifically selecting the connection method with the polarization-maintaining fiber 4, this embodiment can provide any of the following connection methods: fabricating the metasurface microstructure 5 on the front end surface of the polarization-maintaining fiber 4 using two-photon polymerization 3D printing technology, or fabricating the metasurface microstructure 5 using electron beam lithography and then pasting it onto the front end surface of the polarization-maintaining fiber 4.

[0054] It is understood that the metasurface microstructure 5 provided in this application embodiment can be directly disposed on the front end face of the polarization-maintaining fiber 4, or the connection between the metasurface microstructure 5 and the front end face of the polarization-maintaining fiber 4 can be achieved by setting an intermediate connector. Specifically, in this application embodiment, the front end face of the polarization-maintaining fiber 4 can be connected to a beam expander 6; the metasurface microstructure 5 is connected to the front end face of the beam expander 6; the beam expander 6 is used to shape at least two light sources into target waveforms and target sizes and transmit them to the metasurface microstructure 5.

[0055] The beam expander 6 provided in this embodiment can be used to shape the light wave output from the polarization-maintaining fiber 4 into the required waveform and size before incident on the metasurface microstructure 5. Further, the beam expander 6 includes any one of a coreless fiber 61, multiple microlenses, and a hollow support 63. The beam expander 6 can use a coreless fiber 61 of finite length, a beam expander system composed of multiple microlenses, or a hollow support 63. For the coreless fiber 61, its length is determined by the numerical aperture of the polarization-maintaining fiber 4 and the diameter of the metasurface microstructure 5; for the beam expander system composed of multiple microlenses, the focal length and aperture of the microlenses are determined by the numerical aperture of the polarization-maintaining fiber 4 and the diameter of the metasurface microstructure 5, and the specific parameters can be optimized using optical design software.

[0056] As can be seen, the metasurface microstructure 5 can be directly fabricated on the end face of the polarization-maintaining fiber 4 by 3D printing technology, or by electron beam exposure and other processes; or it can be fabricated on the end face of the coreless fiber 61 or multiple microlenses or hollow support 63, and the other end of the coreless fiber 61 can be fused to the polarization-maintaining fiber 4 by a fiber optic fusion splicer; or the metasurface microstructure 5 can be fabricated after the microlens beam expansion system components are fabricated by 3D printing technology.

[0057] In a specific implementation, the embodiments of this application may also provide that the metasurface microstructure 5 includes superatoms 51 and a substrate 52, and the geometry of the superatoms 51 includes, but is not limited to, square columnar or cylindrical shapes, and may also be other complex geometric shapes.

[0058] The following section provides a detailed description of the high-density structured light generation device provided in this application embodiment, using laser light as the light source as an example.

[0059] This application provides a high-density structured light generation device based on fiber-terminated metasurfaces, including a light source assembly 1, a switch box 2, an optical fiber patch cord 3, a polarization-maintaining fiber 4, a metasurface microstructure 5, and a beam expander assembly 6.

[0060] Light source component 1 is used to output laser light of at least three wavelengths. Light source component 1 can be as follows: Figure 2 The supercontinuum laser shown simultaneously outputs multiple laser beams coaxially via an acousto-optic modulator. The laser can have a built-in optical switch 23. Alternatively, multiple single-wavelength lasers can simultaneously output multiple laser beams coaxially via a beam combiner. The light source assembly 1 can also be as follows: Figure 3 The diagram shows multiple single-wavelength lasers simultaneously outputting a single laser beam, and each laser beam can have its own optical switch 23. The laser beams are output to the optical switch box 2 assembly via corresponding fiber optic patch cords 3.

[0061] like Figure 4 , Figure 5As shown, a multi-wavelength laser beam enters the optical switch box 2 through the fiber optic jumper 3 and is then coupled into the polarization-maintaining fiber 4. Without the optical switch 23, the laser needs to be switched on / off and polarization controlled before coupling (if the laser already has the optical switch 23, then a separate optical switch 23 for switching on / off is not required here).

[0062] For a laser coaxially input to a single fiber jumper 3, such as Figure 4 As shown, two fiber optic multiplexers 21 are required. The coaxial laser first passes through the first fiber optic multiplexer 21, coupling the multi-wavelength beams into different optical fibers. Then, three optical switches 23 are used to control the switching of each wavelength beam to control the density of the projected structured light point cloud.

[0063] The multi-wavelength beam composed of three laser beams is transmitted through three polarization controllers 22. The polarization controllers 22 decompose the originally single-polarized beam into two orthogonally polarized beams, such as switching the incident light to 0° and 90° polarization states, or left-handed and right-handed polarization states. Subsequently, the laser beams with different polarizations and wavelengths are coupled into the polarization-maintaining fiber 4 through the second fiber multiplexer 21 for long-distance transmission within the fiber.

[0064] For multiple single-wavelength lasers to simultaneously output multiple laser beams coaxially after passing through a beam combiner, such as Figure 5 As shown, only one fiber optic multiplexer 21 is needed, and the coaxial output multiple laser beams are respectively fed into three optical switches 23 to control the switching of each wavelength beam, thereby controlling the density of the projected structured light point cloud.

[0065] The multi-wavelength beam composed of three laser beams is transmitted through three polarization controllers 22. The polarization controllers 22 decompose the originally single-polarized beam into two orthogonally polarized beams, such as switching the incident light to 0° and 90° polarization states, or left-handed and right-handed polarization states. Subsequently, the laser beams with different polarizations and wavelengths are coupled into the polarization-maintaining fiber 4 through the fiber multiplexer 21 for long-distance transmission within the fiber.

[0066] like Figure 6 , Figure 7 , Figure 8 As shown, the beam expander expands the light emitted from the polarization-maintaining fiber 4 and transmits it to the metasurface microstructure 5.

[0067] Preferably, the beam expander 6 can be adopted Figure 6The coreless optical fiber 61 shown has a length determined by the numerical aperture of the polarization-maintaining fiber 4 and the diameter of the metasurface microstructure 5. The light emitted from the polarization-maintaining fiber 4 is propagated a specific distance in the coreless optical fiber 61 and then expanded to a certain diameter before being incident on the metasurface microstructure 5. The metasurface microstructure 5 shapes the beam and forms a projected structured light point cloud at a set position.

[0068] Preferably, the beam expander 6 can also employ... Figure 7 The microlens beam expander assembly 6 shown consists of a first microlens 621 and a second microlens 622. The spacing, curvature, and diameter of the first microlens 621 and the second microlens 622 are determined by the numerical aperture of the polarization-maintaining fiber 4 and the diameter of the metasurface microstructure 5. The light emitted from the polarization-maintaining fiber 4 is expanded to a certain diameter after passing through the microlens beam expander assembly 6 and then incident on the metasurface microstructure 5. The metasurface microstructure 5 shapes the beam and forms a projected structured light point cloud at a set position.

[0069] Preferably, the beam expander 6 can also employ... Figure 8 The hollow support 63 shown has a length determined by the numerical aperture of the polarization-maintaining fiber 4 and the diameter of the metasurface microstructure 5. The hollow support 63 fixes the metasurface microstructure 5 at a certain distance to the end face of the polarization-maintaining fiber 4. The light emitted from the polarization-maintaining fiber 4 is propagated in free space and expanded to a certain diameter before being incident on the metasurface microstructure 5. The metasurface microstructure 5 shapes the beam and forms a projected structured light point cloud at a set position.

[0070] like Figure 9 As shown, the metasurface microstructure 5 includes superatoms 51 and a substrate 52. The geometry and material of the superatoms 511 are carefully designed, and they are not limited to a rectangular prism shape; they can also be cylindrical or other shapes. The metasurface microstructure 5 composed of superatoms 51 can modulate light of different wavelengths and polarization states and form the desired projection structured light point cloud distribution at specific locations. The substrate 52 can be made of the same material as the superatoms 51, or it can be made of other support materials, depending on the fabrication process requirements.

[0071] The metasurface microstructure 5 can be directly fabricated on the front end of the polarization-maintaining fiber 4 using two-photon polymerization 3D printing technology, with a hollow support 63 or a microlens beam expander 6 fabricated in the middle and then connected, using the same material as the substrate 52; or the metasurface microstructure 5 can be prepared on the substrate 52 using electron beam exposure or other processes and then pasted onto the end face of the polarization-maintaining fiber 4; or the coreless fiber 61 can be connected to the polarization-maintaining fiber 4 using a fiber optic fusion splicer, and then the metasurface microstructure 5 can be prepared on the other end face of the coreless fiber 61.

[0072] like Figure 10As shown, the structured light projection includes random point distribution, uniform point distribution, linear distribution or mesh distribution, or a combination of multiple shapes and patterns.

[0073] The working principle of this invention is as follows:

[0074] like Figure 11 As shown, taking two wavelengths and two polarization states as an example, the multi-wavelength laser emitted from the light source component 1 is polarized and coupled through the optical switch box 2. The beam emitted from the polarization-maintaining fiber 4 contains multiple wavelengths and multiple polarization states. When light of each wavelength and polarization state illuminates the metasurface microstructure 5, it forms corresponding sparse first sparse projection patterns 71, second sparse projection patterns 72, third sparse projection patterns 73, and fourth sparse projection patterns 74. When light of all these wavelengths and polarization states illuminates the metasurface microstructure 5, it forms a superposition pattern of all the corresponding first sparse projection patterns 71, second sparse projection patterns 72, third sparse projection patterns 73, and fourth sparse projection patterns 74 as the final structured light point cloud. Figure 7 This enhances the formation of structured light point clouds. Figure 7 Point cloud density.

[0075] In summary, the high-density structured light generation device provided in this application integrates a metasurface device on the front end of a polarization-maintaining fiber. Light emitted from the light source is transmitted through the fiber to the metasurface device, where it then generates a structured light projection point cloud pattern at a predetermined location. The portion of the fiber extending into the imaging area has a diameter on par with the fiber diameter, resulting in a smaller volume compared to traditional structured light projection systems that transmit light through free space. Furthermore, it can penetrate curved spaces to project structured light point clouds. The light-guiding fiber is a polarization-maintaining fiber, which preserves the polarization characteristics of the beam during transmission. The metasurface microstructure used is a multi-channel multiplexed metasurface, which can modulate the incident light at different wavelengths and polarization channels, thereby simultaneously generating projection patterns from different channels at the predetermined location. By superimposing these patterns, the density of the projection point cloud is significantly increased, thereby improving imaging accuracy in 3D imaging.

[0076] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0077] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0078] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A high-density structured light generation device, characterized in that, include: A light source assembly for generating at least two light sources of different wavelengths; A switch box is connected to the light source assembly via an optical fiber patch cord; the switch box is used to control and couple at least two of the light sources. A polarization-maintaining fiber, one end of which is connected to the switch box; The front end face of the polarization-maintaining fiber is provided with a metasurface microstructure. The polarization-maintaining fiber is used to transmit at least two of the light sources output from the switch box to the metasurface microstructure; the metasurface microstructure is used to modulate at least two of the light sources and form a target structured light distribution at a specified position, so as to improve the point cloud density of the formed structured light point cloud map by superimposing the point cloud images reconstructed by multiple wavelengths and multiple polarization channels. The switch box includes at least one fiber optic multiplexer and at least two polarization controllers; the fiber optic multiplexer is used to couple at least two of the light sources to at least two of the polarization controllers or to couple the light sources output by at least two of the polarization controllers to the polarization-maintaining fiber; the polarization controllers are used to switch the polarization state of each of the light sources.

2. The high-density structured light generation device according to claim 1, characterized in that, The light source assembly includes a laser light source, which includes a supercontinuum laser that simultaneously outputs multiple laser beams coaxially via an acousto-optic modulator or a combination of multiple single-wavelength lasers that simultaneously output multiple laser beams coaxially via a beam combiner.

3. The high-density structured light generation device according to claim 2, characterized in that, The laser may be a visible light laser or an infrared laser.

4. The high-density structured light generation device according to claim 1, characterized in that, The switch box further includes at least two optical switches, one end of each of the at least two optical switches is connected to the optical fiber jumper, and the other end of each of the at least two optical switches is connected to at least two polarization controllers respectively; the optical switches are used to control the on / off state of the light source coupled into the polarization-maintaining fiber.

5. The high-density structured light generation device according to claim 1, characterized in that, The polarization-maintaining fiber includes a single polarization-maintaining fiber or a fiber bundle consisting of multiple polarization-maintaining fibers.

6. The high-density structured light generation device according to claim 1, characterized in that, The connection method between the metasurface microstructure and the polarization-maintaining fiber includes either fabricating the front end face of the polarization-maintaining fiber using two-photon polymerization 3D printing technology, or preparing the metasurface microstructure using electron beam lithography and then attaching it to the front end face of the polarization-maintaining fiber.

7. The high-density structured light generation device according to claim 1, characterized in that, The front end of the polarization-maintaining fiber is connected to a beam expander; the metasurface microstructure is connected to the front end of the beam expander; the beam expander is used to shape at least two of the light sources into a target waveform and target size and transmit them to the metasurface microstructure.

8. The high-density structured light generation device according to claim 7, characterized in that, The beam expander assembly includes any one of the following: coreless optical fiber, multiple microlenses, and hollow support.

9. The high-density structured light generation device according to claim 1, characterized in that, The metasurface microstructure includes superatoms and a substrate, and the geometry of the superatoms includes square prisms and cylindrical shapes.

Images