A radar scanning device and method based on cascaded dual-phase plates

Abstract

This invention discloses a radar scanning device and method based on cascaded dual-phase plates. The device includes: a laser generator, a first phase plate, and a second phase plate; the light output end of the laser generator is aligned with the first phase plate, and the laser generator is used to generate an initial light signal; the first phase plate has a first phase distribution etched on its side away from the laser generator, and the first phase plate is used to perform a first-level modulation processing on the received initial light signal to obtain a first light signal; the second phase plate has a second phase distribution etched on its side facing the first phase plate, and the second phase plate is used to perform a second-level modulation processing on the received first light signal to obtain a two-dimensional grating scanning beam; wherein, the first phase distribution and the second phase distribution are designed to generate a corresponding two-dimensional grating scanning beam based on the phase difference between them, thereby enhancing the flexibility and stability of the lidar scanning system.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, and in particular to a radar scanning device and method based on cascaded dual-phase plates. Background Technology

[0002] With the rapid development of autonomous driving technology, the demand for smaller, lower-energy-consumption, and more stable vehicle-mounted LiDAR is becoming increasingly urgent. Among the core technologies of LiDAR, the beam scanning device is particularly critical, as its performance directly affects the imaging resolution of the LiDAR, thus becoming an important factor in ensuring the safety of autonomous driving. In order to achieve real-time three-dimensional imaging of the road environment during driving, the beam scanning device generates a two-dimensional area array scanning light field and emits scanning laser beams towards the target object to reconstruct a three-dimensional image of the road environment.

[0003] Existing LiDAR systems typically achieve two-dimensional scanning by separately controlling the deflection of a one-dimensional beam in the x and y directions, and then combining these deflections to achieve beam scanning. However, this approach results in a highly complex beam scanning system structure, large size, and high cost of optical components. Furthermore, it limits the system's stability and reliability, making it unsuitable for application in automotive LiDAR systems.

[0004] Therefore, optimizing the structural design of radar scanning devices to achieve two-dimensional scanning has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a radar scanning device and method based on cascaded dual-phase plates, which improves the structure of the radar scanning device and enhances the stability of the system.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a radar scanning device based on a cascaded dual-phase plate, comprising:

[0007] Laser generator, first phase plate and second phase plate;

[0008] The laser generator has its light output end aligned with the first phase plate, and the laser generator is used to generate an initial light signal;

[0009] The first phase plate has a first phase distribution etched on the side away from the laser generator, and the first phase plate is used to perform first-level modulation processing on the received initial optical signal to obtain a first optical signal;

[0010] The second phase plate has a second phase distribution etched on the side facing the first phase plate, and the second phase plate is used to perform secondary modulation processing on the received first optical signal to obtain a two-dimensional grating scanning beam; wherein the first phase distribution and the second phase distribution are designed to generate a corresponding two-dimensional grating scanning beam based on the phase difference between them.

[0011] Furthermore, the planes of the first phase plate and the second phase plate are arranged parallel to each other along the optical axis.

[0012] Furthermore, the first phase plate and the second phase plate are respectively engraved on the corresponding glass substrates.

[0013] Furthermore, the first phase plate is formed by etching the first phase distribution on the back side of the first glass substrate, and the second phase plate is formed by etching the second phase distribution on the front side of the second glass substrate.

[0014] Furthermore, the first phase plate and the second phase plate are designed in a disk shape.

[0015] Furthermore, the first phase plate and the second phase plate are designed as a spatial light modulator, a diffractive optical element, and a metasurface, respectively.

[0016] Furthermore, the phase distribution of the first phase plate is represented by the following formula:

[0017]

[0018] Where (x1,y1) represents the plane where the first phase plate is located, and x1 and y1 represent the horizontal and vertical coordinate values ​​in the (x1,y1) plane, respectively; Φ1(x1,y1) represents the first phase distribution in the rectangular coordinate system, λ represents the working wavelength of the phase plate; a and b represent the coefficients that determine the horizontal and vertical fields of view of the grating scanning, respectively; L and H represent the length and width of the first phase distribution, respectively.

[0019] Furthermore, the phase distribution of the second phase plate is represented by the following formula:

[0020]

[0021] Where (x2,y2) represents the plane where the second phase plate is located, and x2 and y2 represent the horizontal and vertical coordinates in the (x2,y2) plane, respectively; Φ2(x2,y2) represents the second phase distribution in the rectangular coordinate system, which is obtained by horizontally splicing N sub-phases; h represents a constant; L and H represent the length and width of the second phase distribution, respectively.

[0022] Another embodiment of the present invention provides a radar scanning method based on cascaded dual-phase plates, comprising:

[0023] The initial optical signal is emitted to the first phase plate via the laser generator;

[0024] The first phase plate receives the initial optical signal, modulates it with a reference phase, and then transmits it to the second phase plate;

[0025] The second phase plate performs rotational phase modulation on the initial optical signal after the reference phase modulation and then emits it to achieve two-dimensional grating scanning.

[0026] Furthermore, two-dimensional raster scanning at arbitrary frame rates is performed by adjusting the rotation speed of the second phase plate.

[0027] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following:

[0028] The device provided by this invention can be applied to lidar beam scanning systems. By designing two phase plates (a fixed plate and a rotating plate) with different phase distributions etched on them, the structure of the lidar beam scanning system is optimized, improving system stability while significantly reducing costs. Furthermore, by adjusting the rotation speed of the rotating plate, two-dimensional raster scanning at any frame rate can be obtained, providing high flexibility. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a radar scanning device based on a cascaded dual-phase plate in one embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the first phase distribution and the second phase distribution in a rectangular coordinate system in one embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the disk phase distribution etched on a glass substrate by the first phase plate and the second phase plate in one embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the generated N-line scan dot matrix in one embodiment of the present invention;

[0033] Figure 5 This is a schematic flowchart of a radar scanning method based on a cascaded dual-phase plate in one embodiment of the present invention;

[0034] Figure label:

[0035] Among them, 1. First phase plate; 11. First phase distribution in rectangular coordinate system; 12. First disk phase distribution; 2. Second phase plate; 21. Second phase distribution in rectangular coordinate system; 22. Second disk phase distribution; 3. Laser generator. Detailed Implementation

[0036] 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 some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0038] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0040] Addressing the issues of complex structure, large size, high manufacturing cost, and low stability and reliability in existing beam scanning systems, an embodiment of the present invention provides a radar scanning device based on a cascaded dual-phase plate. For details, please refer to... Figure 1 , Figure 1The diagram shown illustrates the structure of a radar scanning device based on a cascaded dual-phase plate according to one embodiment of the present invention. The device includes:

[0041] Laser generator 3, first phase plate 1 and second phase plate 2 respectively etched with different phase distributions.

[0042] from Figure 1 As can be seen, the laser generator 3 has its light output end aligned with the first phase plate 1 to generate the initial light signal, which is the incident laser.

[0043] The first phase plate 1 has a first phase distribution etched on the side away from the laser generator 3, and the first phase plate 1 is used to perform first-level modulation processing on the received initial light signal to obtain a first light signal.

[0044] The second phase plate 2 has a second phase distribution etched on its side facing the first phase plate 1, and the second phase plate 2 is used to perform secondary modulation processing on the received first optical signal to obtain a two-dimensional grating scanning beam. The first phase distribution and the second phase distribution are designed to generate a corresponding two-dimensional grating scanning beam based on the phase difference between them.

[0045] Understandably, the process of achieving grating scanning using the above-described device is as follows: A one-dimensional light beam is emitted by the laser generator 3 and incident on the first phase plate 1 and the second phase plate 2. The first phase plate 1 and the second phase plate 2 convert the one-dimensional light beam into a two-dimensional grating scanning beam by superposition and phase modulation, and then emit it. It is worth noting that the incident laser emitted by the laser generator 3 must be perpendicularly incident on the first phase plate 1.

[0046] In this embodiment, the first phase plate 1 is fixed and used to provide a reference phase; the second phase plate 2 rotates along the optical axis and is used to provide a variable phase. It can be understood that the device in this embodiment actually utilizes the total phase deflection of the incident laser after the two phase plates are superimposed, so that the laser passing through the first and second phase plates forms a dynamic grating scan in space.

[0047] from Figure 1 As can be seen, both phase plates are designed in the shape of disks with a gap between them, and the planes of the first phase plate 1 and the second phase plate 2 are arranged parallel to each other along the optical axis shown in the figure.

[0048] In some embodiments of this example, in order to fully utilize the beam deflection effect, the interval between the two phase plates should be as small as possible. Preferably, the interval d can be set to 1 mm.

[0049] In some embodiments of this example, the first phase plate 1 and the second phase plate 2 are respectively engraved on the corresponding glass substrates, that is, the two phase plates are located on the back and front sides of the two glass substrates respectively.

[0050] In this embodiment, the two phase plates are designed as one of a diffractive optical element, a molded element, and a metasurface device. The diffractive optical element, the molded element, and the metasurface device have optical field phase modulation function, which can realize two-dimensional grating scanning through laser wavefront phase modulation.

[0051] In order to enable the device to perform two-dimensional grating scanning, this embodiment etches different phase distributions on two phase plates, thereby creating a phase difference between the two phase plates.

[0052] In this embodiment, the first phase plate 1 is formed by etching a first phase distribution on the back side of the first glass substrate, and the second phase plate 2 is formed by etching a second phase distribution on the front side of the second glass substrate, thereby realizing precise control of the laser beam and expansion of the scanning dimension.

[0053] The design process of the phase distribution of the two phase plates in this embodiment of the invention is described in detail below. For details, please refer to [link / reference]. Figure 2 As shown, Figure 2 The diagram shown is a schematic diagram of the first phase distribution and the second phase distribution in a rectangular coordinate system according to one embodiment of the present invention. It can be seen that:

[0054] In this embodiment, the first phase plate 1 performs initial phase modulation on the incident laser emitted from the laser generator 3, and the first phase distribution 11 of the first phase plate 1 is represented by the following formula:

[0055]

[0056] Where (x1,y1) represents the plane where the first phase plate is located, and x1 and y1 represent the horizontal and vertical coordinate values ​​in the (x1,y1) plane, respectively; Φ1(x1,y1) represents the first phase distribution in the rectangular coordinate system, λ represents the working wavelength of the phase plate; a and b represent the coefficients that determine the horizontal and vertical fields of view of the grating scanning, respectively; L and H represent the length and width of the first phase distribution, respectively.

[0057] In this embodiment, the second phase plate 2 is modulated again by the laser after the initial phase modulation. The second phase distribution 21 of the second phase plate 2 is represented by the following formula:

[0058]

[0059] Where (x2,y2) represents the plane where the second phase plate is located, and x2 and y2 represent the horizontal and vertical coordinates in the (x2,y2) plane, respectively; Φ2(x2,y2) represents the second phase distribution in the rectangular coordinate system, which is obtained by horizontally splicing N sub-phases; h represents a constant; L and H represent the length and width of the second phase distribution, respectively.

[0060] Understandably, the second phase distribution in Cartesian coordinates is obtained by horizontally splicing N sub-phases, where the size of each sub-phase is equal to the size of the first phase distribution, and the phase distribution of each sub-phase is as follows:

[0061]

[0062] As can be seen from the above formulas, the derivation process represents the phase distribution of the two phase plates in a Cartesian coordinate system. Therefore, this embodiment transforms the phase distributions of the first and second phase plates into phase distributions in a polar coordinate system. For details, please refer to... Figure 3 , Figure 3 The diagram shows a schematic of the phase distribution of a disk etched onto a glass substrate, representing one embodiment of the present invention, with the first phase plate and the second phase plate overlaid on the substrate.

[0063] Understandably, in this embodiment, the first phase distribution in the Cartesian coordinate system is mapped using polar coordinates: The phase distribution Φ1(x1,y1) is then transformed into the first disk phase distribution 12 in polar coordinates, specifically represented by the following formula:

[0064]

[0065] Where (ρ1,θ1) represents the polar coordinate system, ρ1 and θ1 represent the radial and angular coordinate values ​​of the polar coordinate system, respectively, and Ψ1(ρ1,θ1) represents the phase distribution of the first disk.

[0066] Similarly, the second phase distribution in the Cartesian coordinate system is mapped using polar coordinates: The phase distribution 22 of the second disk in polar coordinates is transformed into the following formula:

[0067]

[0068] Where (ρ2,θ2) represents the polar coordinate system, ρ2 and θ2 represent the radial and angular coordinate values ​​of the polar coordinate system, respectively; Ψ2(ρ2,θ2) represents the phase distribution of the second disk; and the constant ρ0 determines the longitudinal interval between any two rows of the scanning light field.

[0069] Based on this, during the modulation process, the phase of the first phase plate 1 and the second phase plate 2 is subtracted, which generates a real-time changing phase slope at the laser incident point. In other words, this phase slope changes as the second phase plate 2 rotates. Specifically,

[0070] The phase difference ψ between the phase distributions Ψ1(ρ1,θ1) and Ψ2(ρ2,θ2) of the first disk in polar coordinates is used to modulate the incident laser beam, thereby achieving two-dimensional deflection of the laser. Since the first phase plate is fixed and the second phase plate is rotated Δθ along the optical axis, the specific expression for the phase distribution of the second disk after rotation is as follows:

[0071]

[0072] The phase difference ψ generated by the superposition of the two disk phase plates will change with the rotation angle Δθ. By unifying the coordinate variables and denoteing ρ1=ρ2=ρ, θ1=θ2=θ, the specific expression for the superposition phase difference ψ is as follows:

[0073]

[0074] The phase slope of the superimposed phase difference ψ is the essential reason for realizing two-dimensional beam scanning, and the tangential direction at the laser incident point... and radial The specific expression for the phase slope is as follows:

[0075]

[0076] in, and is the unit basis vector of the polar coordinate system.

[0077] The above equation shows that the tangential phase slope The radial phase slope is proportional to the rotation angle Δθ of the rotating phase plate; therefore, as the rotating phase plate rotates, the laser scans in the tangential (or horizontal) direction. These are N discrete values, indicating that the radial phase slope controls the laser to perform line-changing scanning in the radial (or vertical) direction, generating an N-line scan. For details, please refer to... Figure 4 , Figure 4 The diagram shown is a schematic representation of an N-line scan dot matrix generated in one embodiment of the present invention. As an example, as shown... Figure 4 As shown, it displays the scan dot matrix when N=8 and 20.

[0078] In summary, the device provided in this embodiment of the invention can be applied to a lidar beam scanning system. By cascading dual phase plates to deflect and modulate the incident light, and with a stationary and a moving plate design, the structure of the lidar beam scanning system is greatly optimized. Furthermore, the high-speed rotation of the phase plates enables grating scanning with arbitrary line counts and fields of view. This device can efficiently and conveniently convert a one-dimensional incident beam into a two-dimensional grating, significantly reducing costs while improving system stability.

[0079] Based on the above-described device embodiments, an embodiment of the present invention provides a radar scanning method based on cascaded dual-phase plates. For details, please refer to... Figure 5 , Figure 5 The diagram shown is a schematic flowchart of a radar scanning method using a cascaded dual-phase board according to one embodiment of the present invention, including the following steps:

[0080] S1. The initial light signal is emitted to the first phase plate through the laser generator.

[0081] S2. The first phase plate receives the initial optical signal, modulates it with a reference phase, and then transmits it to the second phase plate.

[0082] S3. The second phase plate performs rotational phase modulation on the initial optical signal after the reference phase modulation and then emits it to achieve two-dimensional grating scanning.

[0083] In this embodiment, the second phase plate is rotatable, providing a changing phase, and rotates at high speed along the optical axis.

[0084] Based on this, it can be understood that the frame rate of a two-dimensional raster scan is equal to the rotation speed of the rotating phase plate. By adjusting the rotation speed of the rotating plate, a raster scan with any frame rate can be obtained, which is highly flexible.

[0085] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A radar scanning device based on cascaded dual-phase plates, characterized in that, The device includes a laser generator, a first phase plate, and a second phase plate; The laser generator has its light output end aligned with the first phase plate, and the laser generator is used to generate an initial light signal; The first phase plate has a first phase distribution etched on the side away from the laser generator, and the first phase plate is used to perform first-level modulation processing on the received initial optical signal to obtain a first optical signal; The second phase plate has a second phase distribution etched on its side facing the first phase plate. The second phase plate is used to perform secondary modulation processing on the received first optical signal to obtain a two-dimensional grating scanning beam. The first phase distribution and the second phase distribution are designed to generate a corresponding two-dimensional grating scanning beam based on the phase difference between them. Specifically, the phase distributions of the first and second phase plates are transformed into phase distributions in polar coordinates. The incident laser is controlled by the phase difference between the first phase distribution and the second phase distribution in polar coordinates to achieve two-dimensional deflection of the laser. The phase difference changes with the rotation angle of the second phase plate along the optical axis. The phase distribution of the first phase plate is represented by the following formula: The phase distribution of the second phase plate is represented by the following formula: Wherein, (x1,y1) represents the plane where the first phase plate is located, and x1 and y1 represent the horizontal and vertical coordinate values ​​in the (x1,y1) plane, respectively; Φ1(x1,y1) represents the first phase distribution in the rectangular coordinate system, and λ represents the working wavelength of the phase plate; a and b represent the coefficients that determine the horizontal and vertical fields of view of the grating scanning, respectively; L1 and H1 represent the length and width of the first phase distribution, respectively; (x2,y2) represents the plane where the second phase plate is located, and x2 and y2 represent the horizontal and vertical coordinate values ​​in the (x2,y2) plane, respectively; Φ2(x2,y2) represents the second phase distribution in the rectangular coordinate system, which is obtained by horizontally splicing N sub-phases; h represents a constant; L2 and H2 represent the length and width of the second phase distribution, respectively.

2. The radar scanning device based on cascaded dual-phase plates as described in claim 1, characterized in that, The planes of the first phase plate and the second phase plate are arranged parallel to each other along the optical axis.

3. The radar scanning device based on cascaded dual-phase plates as described in claim 1, characterized in that, The first phase plate and the second phase plate are respectively engraved on the corresponding glass substrates.

4. The radar scanning device based on cascaded dual-phase plates as described in claim 1, characterized in that, The first phase plate is formed by etching the first phase distribution on the back side of the first glass substrate, and the second phase plate is formed by etching the second phase distribution on the front side of the second glass substrate.

5. The radar scanning device based on cascaded dual-phase plates as described in claim 1, characterized in that, The first phase plate and the second phase plate are designed in the shape of a disk.

6. The radar scanning device based on cascaded dual-phase plates as described in claim 1, characterized in that, The first phase plate and the second phase plate are designed as a spatial light modulator, a diffractive optical element, and a metasurface, respectively.

7. A radar scanning method based on cascaded dual-phase plates, applied to the radar scanning device based on cascaded dual-phase plates as described in any one of claims 1 to 6, characterized in that, include: The initial optical signal is emitted to the first phase plate via the laser generator; The first phase plate receives the initial optical signal, modulates it with a reference phase, and then transmits it to the second phase plate; The second phase plate performs rotational phase modulation on the initial optical signal after the reference phase modulation and then emits it to achieve two-dimensional grating scanning.

8. The radar scanning method based on cascaded dual-phase plates as described in claim 7, characterized in that, Two-dimensional raster scanning at arbitrary frame rates is performed by adjusting the rotation speed of the second phase plate.

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