TOF module based on metasurface and sweeping robot

Abstract

The utility model relates to a TOF module based on a metasurface and a sweeping robot, and belongs to the field of optical devices.The TOF module comprises a transmitting end and a receiving end, and the transmitting end and the receiving end are located at the same horizontal position and placed at intervals; the transmitting end comprises a light source and a metasurface projection device; the receiving end comprises a CMOS sensor and a metasurface receiving device. According to the invention, the collimation and beam splitting functions of the VCSEL light source are realized at the same time by using the single metasurface, and the dot matrix projection function of the TOF module transmitting end in the sweeping robot can be realized.

Description

Technical Field

[0001] This application belongs to the field of optical devices, and specifically relates to a TOF module based on metasurface and a sweeping robot. Background Technology

[0002] With the development of the smart furniture industry, robotic vacuum cleaners are gradually entering the public eye. They can complete the task of cleaning floors in a house by planning paths using artificial intelligence. Current technology uses a lidar sensor mounted on top of the robot for obstacle avoidance, which is used for path planning and mapping. However, this approach has two drawbacks: firstly, the lidar requires mechanical rotation, reducing its lifespan; secondly, because the lidar module is above the horizontal line, the robot cannot accurately avoid low obstacles such as door sills, limiting its usability.

[0003] The Time-of-Flight (TOF) method, which measures the three-dimensional structure of environmental targets by measuring the time interval between the transmission and reception of the pulse signal emitted by the projection module, offers the possibility of improving the obstacle avoidance performance of robotic vacuum cleaners.

[0004] Existing technologies have replaced the transmitter of lidar in robotic vacuum cleaners by using a VCSEL array combined with a collimating lens and a nanoimprint diffraction element (DOE). However, this method requires two optical lenses, resulting in high cost and assembly difficulty. On the receiver side, a lens composed of multiple lenses is typically used, which is bulky and expensive. These issues limit the application of Time-of-Flight (TOF) modules in robotic vacuum cleaners. Utility Model Content

[0005] This application provides a TOF module and a robotic vacuum cleaner based on metasurfaces to at least solve the above-mentioned technical problems existing in the prior art.

[0006] One embodiment of this application provides a TOF module based on metasurfaces, including a transmitter and a receiver, wherein the transmitter and the receiver are located at the same horizontal position and are placed at intervals; the transmitter includes a light source and a metasurface projection device; the receiver includes a CMOS sensor and a metasurface receiving device.

[0007] In one embodiment, the metasurface projection device includes a first substrate and a first metasurface disposed on the first substrate; the metasurface receiving device includes a second substrate and a second metasurface disposed on the second substrate.

[0008] In one embodiment, both the first and second metasurfaces achieve their desired phase distribution through the size and arrangement of microstructures, with phase variations ranging from 0 to 2π.

[0009] In one embodiment, the arrangement of the microstructures on the first metasurface is the same as that on the second metasurface; however, the size of the microstructures at each location on the first metasurface is different from that on the second metasurface.

[0010] In one embodiment, the light source is a VCSEL array light source with an infrared wavelength and an emission angle range of 18°-26°.

[0011] In one embodiment, the operating wavelength of the light source is 850nm, 905nm, or 940nm.

[0012] In one embodiment, the field of view of the metasurface receiving device is 100°-130°.

[0013] In one embodiment, the CMOS sensor has 300,000 to 2,000,000 pixels.

[0014] Another embodiment of this application provides a robotic vacuum cleaner, including at least two of the above-mentioned TOF modules.

[0015] In one possible implementation, two TOF modules are included, each of which includes a transmitter and a receiver, the transmitter and the receiver being located at the same horizontal position and placed at an interval. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the sweeping robot in the embodiments of this application;

[0017] Figure 2 This is a schematic diagram of the transmitter end of the TOF module in the embodiments of this application;

[0018] Figure 3 This is a schematic diagram of the receiver end of the TOF module in the embodiments of this application;

[0019] Figure 4 This is a schematic diagram of the metasurface unit structure in an embodiment of this application;

[0020] Figure 5 This is a schematic diagram illustrating the relationship between microstructure diameter, phase, and transmittance in the embodiments of this application;

[0021] Figure 6 This is a schematic diagram of the dot matrix effect projected by the transmitting end in an embodiment of this application;

[0022] Figure 7 This is a schematic diagram of the dot matrix effect received by the receiving end in an embodiment of this application; Detailed Implementation

[0023] The present application will now be described in further detail with reference to the accompanying drawings.

[0024] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] This application provides a TOF module and a robotic vacuum cleaner based on a metasurface. The metasurface simultaneously achieves collimation and beam splitting of a VCSEL light source, enabling dot matrix projection from the TOF module's transmitter in the robotic vacuum cleaner. Furthermore, by replacing the lens of the imaging module with a metasurface, the emitted dot matrix is ​​collected and imaged onto a CMOS sensor, ultimately realizing the obstacle avoidance module of the robotic vacuum cleaner.

[0026] Specifically, this application provides a Time-of-Flight (TOF) module that can be used in a robotic vacuum cleaner. The main structure includes a transmitter and a receiver, which are located at the same horizontal level and spaced apart. The transmitter includes a light source and a metasurface projection device, while the receiver includes a CMOS sensor and a metasurface receiving device.

[0027] Specifically, the metasurface projection device includes a first substrate and a first metasurface placed on the first substrate. The first metasurface is composed of several microstructures, and the phase distribution required by the first metasurface can be achieved by the type, size and arrangement of the microstructures. Its phase change range is within 0-2π.

[0028] Optionally, the first substrate can be made of a transparent material such as silicon dioxide. The material of the microstructure is selected as a high refractive index material suitable for the working wavelength of the light source. The refractive index of the microstructure and the first substrate have the following relationship: n 微结构 >n 第一基底 The shape of the microstructure can be a nanopillar or a nanopore, and it needs to have a transmittance of >85% at the designed wavelength. The microstructure includes, but is not limited to, rectangular nanopillars, nanocross pillars, etc., and the arrangement of the microstructure can be tetragonal or hexagonal.

[0029] In this embodiment, the light source is a vertical-cavity surface-emitting laser (VCSEL) array, with an operating wavelength of infrared light and an emission angle range of 18°-26°. Specifically, its operating wavelength can be infrared light such as 850nm, 905nm, or 940nm.

[0030] The laser emitted by the VCSEL is collimated and split after passing through the metasurface, projecting a rectangular lattice of dots in space with a horizontal angle between 100° and 130° and a vertical angle between 5° and 40°.

[0031] Specifically, the metasurface receiving device includes a second substrate and a second metasurface placed on the second substrate. The second metasurface is composed of several microstructures, and the phase distribution required by the metasurface can be achieved by the type, size and arrangement of the microstructures, with the phase change range being within 0-2π.

[0032] Optionally, the second substrate can be made of a transparent material such as silicon dioxide. The material of the microstructure is selected as a high-refractive-index material suitable for the working wavelength of the light source. The refractive index of the microstructure and the second substrate have the following relationship: n 微结构 >n 第二基底 The shape of the microstructure can be a nanopillar or a nanopore, and it needs to have a transmittance of >85% at the designed wavelength. The microstructure includes, but is not limited to, rectangular nanopillars, nanocross pillars, etc., and the arrangement of the microstructure can be tetragonal or hexagonal.

[0033] It should be noted that the materials and microstructures of the metasurface receiving device are the same as those of the metasurface projection device, but the microstructure dimensions at each location are different from those of the projection part, in order to collect light reflected at large angles. The collected light is then focused onto the CMOS sensor.

[0034] That is, both the first and second metasurfaces achieve their desired phase distribution through the size and arrangement of microstructures, with phase variations ranging from 0 to 2π. The arrangement of microstructures on the first metasurface is the same as that on the second metasurface, but the size of the microstructures at each location on the first metasurface differs from that on the second metasurface.

[0035] Specifically, the CMOS sensor is a detector capable of detecting VCSEL infrared light, and its pixel count can be 30W-200W.

[0036] This application also discloses a robotic vacuum cleaner comprising at least two of the aforementioned TOF modules.

[0037] In some embodiments, the robotic vacuum cleaner includes two Time-of-Flight (TOF) modules, each including a transmitter and a receiver, which are located at the same horizontal position and spaced apart.

[0038] Figure 1 This is a schematic diagram of a robotic vacuum cleaner with two Time-of-Flight (TOF) modules.

[0039] Two TOF modules are located on the front and rear sides of the robotic vacuum cleaner 1, respectively, and are designated as the first module and the second module. The first module includes a first transmitting module 11 and a first receiving module 13, and the second module includes a second transmitting module 12 and a second receiving module 14.

[0040] Specifically, the first transmitting module 11 and the first receiving module 13 are arranged on the same horizontal line, and the second transmitting module 12 and the second receiving module 14 are arranged on the same horizontal line. After the dot matrix projected by the first transmitting module 11 and the second receiving module 12 is received by the first receiving module 13 and the second receiving module 14, the surrounding environment can be modeled in three dimensions by analyzing the changes in the intensity and shape of the projected speckle, thus completing the obstacle avoidance function.

[0041] The structure of the first launching module 11 is as follows: Figure 2 As shown, the first emission module 11 includes a light source 111 and a metasurface projection device 112. The metasurface projection device 112 includes a first substrate and a first metasurface placed on the first substrate.

[0042] Specifically, the light source 111 can be a VCSEL array with a divergence angle range of 18°-26°. After being collimated and split by the metasurface projection device 112, the light source 111 will be projected into a dot matrix in space.

[0043] In one embodiment, the divergence angle of the light source 111 is 23°, the distance between the light source 111 and the metasurface projection device 112 is 2.2 mm, and the thickness of the metasurface unit in the metasurface projection device 112 is 0.5 mm.

[0044] The structure of the first receiving module 13 is as follows: Figure 3 As shown, the first receiving module 13 includes a CMOS sensor 131 and a metasurface receiving device 132. The metasurface receiving device 132 includes a second substrate and a second metasurface placed on the second substrate, the second metasurface being composed of a plurality of microstructures.

[0045] Light in space is focused by the metasurface receiving device 132 and then received by the CMOS sensor 131.

[0046] Specifically, the field of view of the metasurface receiving device 132 is 100°-130°.

[0047] In one embodiment, the metasurface receiving device 132 has a field of view of 130°, a focal length of 0.8 mm, and a metasurface unit thickness of 0.7 mm.

[0048] It should be noted that both the metasurface projection device 112 and the metasurface receiving device 131 are composed of several metasurface units. Each metasurface unit is composed of any microstructure and a substrate. A schematic diagram of the composition of the metasurface unit is shown below. Figure 4 In this embodiment, nanopillars were chosen as the shape of the microstructure. Phase modulation can be achieved by changing the microstructure diameter d. Figure 5 The relationship between the phase and transmittance of some microstructures and their diameter d is given. By combining units with different diameters, the direction of light can be controlled to achieve beam splitting or focusing.

[0049] Figure 6 The effect of the laser emitted by the VCSEL array after being collimated and split by the first emission module 11 is as follows: the overall angle in the horizontal direction of the entire array is 115°, and the angle in the vertical direction is 20°.

[0050] Figure 7 The dot matrix distribution received by the first receiving module 13 has a reduced distortion due to the opposite distortion of the metasurfaces at the transmitting and receiving ends. By utilizing the received dot matrix in conjunction with a corresponding algorithm, distance detection of surrounding objects can be achieved, thus realizing obstacle avoidance.

[0051] As described above, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0052] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A TOF module based on metasurfaces, characterized in that: It includes a transmitter and a receiver, which are located at the same horizontal position and placed at intervals. The transmitting end includes a light source and a metasurface projection device; The receiving end includes a CMOS sensor and a metasurface receiving device.

2. The TOF module based on metasurfaces according to claim 1, characterized in that: The metasurface projection device includes a first substrate and a first metasurface disposed on the first substrate; The metasurface receiving device includes a second substrate and a second metasurface disposed on the second substrate.

3. The TOF module based on metasurfaces according to claim 2, characterized in that: Both the first and second metasurfaces achieve their desired phase distribution through the size and arrangement of microstructures, with phase variations ranging from 0 to 2π.

4. The TOF module based on metasurfaces according to claim 3, characterized in that: The arrangement of the microstructures of the first metasurface is the same as that of the second metasurface; The dimensions of the microstructures at various locations in the first metasurface are different from those in the second metasurface.

5. The TOF module based on metasurfaces according to claim 1, characterized in that: The light source is a VCSEL array light source with an infrared wavelength and an emission angle range of 18°-26°.

6. The TOF module based on metasurfaces according to claim 5, characterized in that: The operating wavelength of the light source is 850nm, 905nm, or 940nm.

7. A TOF module based on metasurfaces according to claim 1, characterized in that: The field of view of the metasurface receiving device is 100°-130°.

8. A TOF module based on metasurfaces according to claim 1, characterized in that: The CMOS sensor has 300,000 to 2,000,000 pixels.

9. A robotic vacuum cleaner, characterized in that, It includes at least two TOF modules as described in claims 1-8.

10. The sweeping robot according to claim 9, characterized in that, It includes two TOF modules, each of which includes a transmitter and a receiver, which are located at the same horizontal position and placed at an interval.

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