Laser radar based on non-mechanical solid-state light source

Abstract

The invention discloses a laser radar based on a non-mechanical solid-state light source, and the laser radar comprises a transmitting array, the transmitting array comprises a plurality of sub-arrays, and each sub-array comprises a phase modulation unit and a transmitting antenna unit; a scanning area of the emission array is divided into a plurality of sub-areas, the sub-arrays are in one-to-one correspondence with the sub-areas, and the sub-arrays are used for scanning the corresponding sub-areas. According to the invention, the phase modulation unit is used to deflect the light and then the light is transmitted through the transmitting antenna unit for scanning, no mechanical mechanism needs to be arranged, and the cost and size of the laser radar are effectively reduced; according to the invention, the emission array is divided into a plurality of sub-arrays, the scanning area of the emission array is divided into a plurality of sub-areas, the sub-arrays and the sub-areas are in one-to-one correspondence, and two-dimensional scanning with a large field angle, high scanning precision and high scanning speed is realized through a partition scanning mode that the large scanning area is divided into a plurality of small sub-areas.

Description

Technical Field

[0001] This application relates to the field of laser scanning, and more particularly to a lidar based on a non-mechanical solid-state light source. Background Technology

[0002] Lidar (light detection and ranging) is a 3D ranging device that measures the distance to objects in a scene by utilizing the time of flight (ToF) of a light signal from emission, reflection, and reception. Lidar is primarily used in consumer electronics such as smartphones, tablets, and robotic vacuum cleaners, as well as in automation fields such as machine vision, autonomous driving, surveillance, and drones.

[0003] The core components of a lidar system can be divided into three parts: the light source emitting component, the light source receiving component, and the signal processing center. The lidar's light source emitting component emits 1D or 2D light pulses into the scene to cover a certain field of view. The receiving chip in the light source receiving component receives the pulse echoes reflected back from the target object. The signal processing center is responsible for recording the flight time of each received light signal and generating histograms and point cloud maps, thereby achieving 2D distance detection. Ideally, a lidar needs to cover 360 degrees of horizontal and vertical distance information; therefore, it is generally required that the lidar can emit and receive light over a wide angle.

[0004] Traditional mechanical LiDAR typically uses a vertically aligned array of light sources, driven by a motor system to rotate horizontally, achieving 360-degree two-dimensional scanning. However, mechanical LiDAR often requires multiple discrete components, leading to complex optical path debugging and assembly, low production efficiency, and high component costs, thus reducing its competitiveness. The high-frequency rotation of the motor and the complex mechanical structure also result in a mean time between failures (MTBF) of only 1000-3000 hours, falling short of the minimum requirement of 13000 hours. This aging issue of the motor system further reduces the reliability of mechanical LiDAR. Furthermore, when applied to autonomous driving in automobiles, mechanical LiDAR needs to be positioned at the highest point of the vehicle to avoid obstruction. However, placing mechanical LiDAR and reinforcing structures on the roof can affect the vehicle's center of gravity, impacting driving safety. The protruding LiDAR is also more susceptible to damage, and its placement on the roof significantly affects the vehicle's styling.

[0005] To overcome the problems inherent in mechanical LiDAR, hybrid solid-state LiDAR has been proposed in recent years, employing methods such as rotating mirror scanning, prism scanning, or galvanometer scanning based on microelectromechanical systems (MEMS). Among these, the galvanometer scanning scheme based on MEMS is the most representative. A MEMS galvanometer is a miniature integrated system that utilizes microfabrication technology to mass-produce channels, holes, cantilever arms, films, cavities, and other micromechanical structures on a chip, and then integrates them with corresponding circuits using integrated circuit manufacturing technology. Light deflection on the microstructure is achieved by controlling the rotation of a rotating arm. Compared to mechanical LiDAR, hybrid solid-state MEMS LiDAR significantly reduces cost and size. However, the presence of micromechanical structures such as rotating arms in hybrid solid-state MEMS LiDAR raises questions about its reliability, stability, and integration. Summary of the Invention

[0006] To address one of the technical problems existing in the prior art, this application provides a lidar based on a non-mechanical solid-state light source, which achieves a large field of view, high precision, and high-speed scanning effect.

[0007] According to a first aspect of this application, a lidar based on a non-mechanical solid-state light source is provided. The lidar includes a transmitting array, which includes multiple subarrays. Each subarray includes a phase modulation unit and a transmitting antenna unit. The scanning area of ​​the transmitting array is divided into multiple sub-regions, and the subarrays and sub-regions correspond one-to-one. The subarrays are used to scan the corresponding sub-regions.

[0008] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, the transmitting array includes a light source module and an optical phased array module. The light emitted by the light source module is phase-modulated by the optical phased array module and then output. The optical phased array module consists of the phase-modulation unit of each subarray and the corresponding transmitting antenna unit.

[0009] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, when the light source module outputs waveguide light to the optical phased array module, the optical phased array module also includes a beam splitter, and the multiple parallel beams generated by the beam splitter enter the corresponding phase modulation unit through optical waveguides respectively.

[0010] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, when the lidar scans, the sub-arrays scan simultaneously or the sub-arrays scan at different times.

[0011] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, the scanning pixel array of each subarray is configured to be the same.

[0012] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, the subarray has a variety of different scanning pixel arrays, and the scanning pixel array of each subarray can be designed according to the actual resolution requirements, so that different subarrays have different scanning pixel arrays.

[0013] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, the emitting array further includes a light output module, which is disposed behind the optical phased array module along the optical path direction.

[0014] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, the light output module includes a liquid crystal polarizing grating, and a linear polarizer is disposed in front of the liquid crystal polarizing grating.

[0015] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, the light output module includes a Bragg volume grating.

[0016] According to the lidar based on a non-mechanical solid-state light source provided in the first aspect of this application, the light output module includes an external lens, which improves the quality of the light spot.

[0017] This application has the following beneficial effects:

[0018] The lidar based on a non-mechanical solid-state light source of this application uses a phase-tuning unit to deflect the light before transmitting it through a transmitting antenna unit for scanning. This eliminates the need for mechanical mechanisms, effectively reducing the cost and size of the lidar. Furthermore, this application divides the transmitting array into multiple sub-arrays, and the scanning area of ​​the transmitting array is divided into multiple sub-regions. The sub-arrays and sub-regions correspond one-to-one. By dividing a large scanning area into multiple small sub-regions, a two-dimensional scanning method with a large field of view, high scanning accuracy, and high scanning speed is achieved.

[0019] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solution of this application, the following description will be provided in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort. In the drawings:

[0021] Figure 1 This is a block diagram of the lidar transmitting array provided in this application;

[0022] Figure 2 This is a block diagram of the non-waveguide optical phased array provided in this application;

[0023] Figure 3 This is a block diagram of the waveguide optical phased array provided in this application;

[0024] Figure 4 This is a schematic diagram of the scanning area array when using an optical phased array for scanning.

[0025] Figure 5 It is Figure 4 A schematic diagram showing the scanning area divided into multiple equivalent sub-regions;

[0026] Figure 6 This is a schematic diagram of dividing the scanned area into multiple sub-regions with different pixel arrays.

[0027] Explanation of icon numbers:

[0028] The light source module 100, optical phased array module 200, phase modulation unit 201, transmitting antenna unit 202, beam splitter 204, optical waveguide 205, and optical output module 300 are included. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0030] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0031] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0032] The following is in conjunction with the appendix Figure 1 To be continued Figure 6 The provided embodiments further illustrate the lidar based on a non-mechanical solid-state light source proposed in this application.

[0033] Please refer to Figures 1 to 6 This application provides a lidar based on a non-mechanical solid-state light source. The lidar includes a transmitting array, which comprises multiple sub-arrays. Each sub-array includes a phase modulation unit 201 and a transmitting antenna unit 202. Figure 5 As shown, in this application, the scanning area of ​​the transmitting array is divided into multiple sub-regions, and the sub-arrays and sub-regions correspond one-to-one. Each sub-array is used to scan the corresponding sub-region, thereby achieving partitioned scanning. The lidar based on a non-mechanical solid-state light source in this application uses the phase modulation unit 201 to deflect the light before transmitting it through the transmitting antenna unit 202 for scanning. There is no need to set up a mechanical mechanism, which effectively reduces the cost and size of the lidar. In this application, the transmitting array is divided into multiple sub-arrays, and the scanning area of ​​the transmitting array is also divided into multiple sub-regions. The sub-arrays and sub-regions correspond one-to-one, and the superposition of multiple sub-regions can achieve a large field of view scanning. By dividing the large scanning area into multiple small sub-regions for partitioned scanning, the scanning accuracy and scanning speed can be improved, while reducing the technical difficulty brought about by large-area, high-precision scanning.

[0034] like Figure 1As shown, the transmitting array includes a light source module 100 and an optical phased array module 200. The light source module 100 is mainly responsible for providing a light source coupled into the optical phased array module 200. An optical phased array (OPA) is based on electro-optic or thermo-optic phase modulation. Under the influence of an electric field or temperature, it changes the refractive index of the material and the phase of light. Through methods such as light interference or polarization, it causes abrupt changes in light intensity or a shift in the light path, achieving scanning at different angles without the need for a mechanical structure to rotate the light source. In this application, the optical phased array module 200 consists of a phase modulation unit 201 and a transmitting antenna unit 202 in each subarray. The phase modulation unit 201 in each subarray can be composed of an independent phase modulation chip or different array units within a single phase modulation chip. The optical phased array module 200 effectively adjusts the phase difference of light through thermo-optic or electro-optic effects, and changes the emitted light angle through the diffraction and interference properties of light, thereby achieving a deflection of the scanning angle and increasing the scanning field of view (FoV). In some embodiments, the optical phased array module 200 can be made of any one of the following materials: liquid crystal, silicon, silicon nitride, or lithium niobate thin film. Optical phased array modules 200 made of different materials have different performance characteristics to adapt to different usage environments and requirements. For example, liquid crystal optical phased arrays (LCOPA) and MEMS-type optical phased arrays are often used for phase modulation of non-waveguide light, while optical phased arrays made of materials such as silicon (Si), silicon nitride (SiN), or lithium niobate thin film (LNOI) are often used for phase modulation of waveguide light. Furthermore, when scanning based on an optical phased array, a common approach is to equip multiple point light sources in the vertical direction. By deflecting the light path through the optical phased array, the multiple point light sources move synchronously in the horizontal direction for scanning. Figure 4 As shown, Figure 4The rectangular frame represents the scanning area, the solid circle represents the point light source, and the dashed hollow circle represents the far-field spot formed by the optical phased array after deflecting the optical path. Another approach involves using only one point light source. Through the optical phased array's deflection of the optical path, the point light source first moves horizontally in the first row. After the first row is scanned, the optical phased array controls the point light source to enter the initial position of the second row, where it moves horizontally again. This process is repeated multiple times to complete the scan. Using a single light source to simultaneously scan both horizontally and vertically can significantly reduce hardware costs. However, this approach requires high scanning speeds, and its technical principle is only applicable to waveguide-type optical phased arrays. When using a non-mechanical solid-state light source for scanning, the key parameters of field of view and scanning accuracy are related to the array size and number of arrays in the optical phased array. Generally, the smaller the size of the transmitting array, the larger the scanning field of view, while the larger the number of transmitting arrays, the higher the scanning accuracy. However, as the number of transmitter arrays increases, the complexity of the drive control circuit increases exponentially. Simultaneously, the smaller the size of the transmitter array, the higher the precision requirements of the processing platform, and it also introduces serious optical crosstalk problems. Therefore, as... Figure 5 and Figure 6 As shown, in this application, the emission array of the lidar is divided into multiple sub-arrays, and the scanning area is divided into multiple sub-regions. Each sub-array is used to scan the corresponding sub-region. By using partitioned scanning, the technical difficulty of large-area, high-precision scanning is reduced, while the scanning accuracy and scanning speed are improved.

[0035] like Figure 2 As shown, in some embodiments, when the input light is non-waveguide light, the optical phased array module 200 adopts a non-waveguide optical phased array, which is also generally referred to as a spatial light modulator, including liquid crystal optical phased arrays or MEMS optical phased arrays. Among them, liquid crystal optical phased arrays include liquid crystal on silicon (LCoS) and liquid crystal on glass (LCoG). The optical phased array module 200 consists of a phase modulation unit 201 and a transmitting antenna unit 202 for each subarray. The optical phased array module 200 also includes an electrical control module 203, which is connected to each phase modulation unit 201. The electrical control module 203 controls the operation of each phase modulation unit 201, including whether the phase modulation unit 201 is turned on and put into operation, and the angle at which the phase modulation unit 201 deflects the optical path. Under the control of the electrical control module 203, the phase modulation unit 201 changes the phase difference of each light path to deflect it, and then couples the light into free space through the transmitting antenna unit 202 to achieve mechanical-free scanning.

[0036] like Figure 3As shown, in some embodiments, when the input light is waveguide light (i.e., the light source module 100 outputs waveguide light to the optical phased array module 200), the optical phased array module 200 adopts a waveguide-type optical phased array. The waveguide-type optical phased array has higher integrability. In addition to the phase modulation unit 201, the transmitting antenna unit 202, and the electrical control module 203, the optical phased array module 200 also includes a beam splitter 204. The beam splitter 204 is connected to each phase modulation unit 201 through the optical waveguide 205. The beam splitter 204 splits the input waveguide light into multiple parallel beams. Each parallel beam enters the corresponding phase modulation unit 201 through the connection of the optical waveguide 205.

[0037] like Figure 4 and Figure 5 As shown, taking a liquid crystal optical phased array as an example, a detailed illustration of the lidar based on a non-mechanical solid-state light source of this application is provided. In some embodiments, the lidar may have a field of view of 30 degrees in the horizontal direction, dividing the entire scanning area into 15 sub-regions ( Figure 5 If only four sub-regions are displayed (in this case, only four are shown), then the field of view of each sub-region is 2 degrees. Stitching together 15 sub-regions will achieve a 30-degree field of view in the horizontal direction. Simultaneously, scanning can be performed by the light sources of all 15 sub-regions, increasing the imaging time per frame of the lidar and thus the frame rate. Taking a 20Hz lidar frame rate as an example, if the horizontal angular accuracy is 0.1 degrees, then one frame will have 300 imaging points. For liquid crystal optical phased arrays, the fastest response speed of the crystal is generally 2ms. With a frame time of 50ms, simultaneous scanning of 15 sub-regions can form a maximum of 375 imaging points. The lidar based on a non-mechanical solid-state light source of this application can ensure high accuracy over a wide viewing angle while significantly improving scanning speed, meeting the frame rate requirements of lidar. The number of sub-regions generally depends on the type of optical phased array. If it is a waveguide-type optical phased array, the scanning speed and scanning field of view are larger, so the number of sub-regions can be smaller than that of a liquid crystal optical phased array.

[0038] Furthermore, when the lidar is scanning, each subarray can be activated simultaneously. Additionally, depending on the device's response speed, and provided the scanning frame rate is met, the subarrays can be activated at different times. For example, with 15 zones, the central 6 subarrays can be activated first to scan, followed by the remaining 9 subarrays, to reduce instantaneous power consumption, thereby lowering the power and heat dissipation requirements of the device and reducing costs.

[0039] like Figure 5 As shown, when dividing the subarrays, the scan pixel array of each subarray can be set to the same scan pixel array. Furthermore, as... Figure 6As shown, when dividing the subarrays, the scanning pixel array of each subarray can be designed separately according to the actual resolution requirements, so that different subarrays can have different scanning pixel arrays. For example, generally, LiDAR requires high resolution in the center of the image and low resolution around the edges; the design can be based on this principle. Figure 6 The scanning pixel arrays of the sub-arrays corresponding to each sub-region in the image have more scanning pixel arrays in the middle sub-array and smaller scanning pixel arrays in the sub-arrays on both sides. This can control the imaging resolution and effectively reduce the amount of data while meeting the image resolution requirements.

[0040] like Figure 1 As shown, in some embodiments, the transmitting array further includes a light output module 300, which is positioned behind the optical phased array module 200 along the optical path. The light output module 300 can serve as a selective module to increase the field of view or change the spot quality. For example, in scenarios where speed requirements are not high but a large field of view is needed, a liquid crystal polarization grating (LCPG) can be used as the light output module 300. Since the liquid crystal polarization grating has polarization requirements for the light source, a linear polarizer is required in front, i.e., the light output module 300 is composed of the linear polarizer and the liquid crystal polarization grating. Using a liquid crystal polarization grating can double the deflection angle of the optical phased array module 200, but it will reduce the scanning accuracy. Alternatively, a volume Bragg grating (VBG) can be used instead of a liquid crystal polarization grating to achieve the same effect. Since the volume Bragg grating is not polarization sensitive, a linear polarizer is not required, reducing the number of components. To further improve the quality of the light spot, such as collimation and optical power density, the optical output module 300 may also include an external lens, which can effectively improve the quality of the light spot.

[0041] It is understood that the above embodiments only illustrate preferred embodiments of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that, for those skilled in the art, without departing from the concept of this application, the above technical features can be freely combined, and several modifications and improvements can be made, all of which fall within the protection scope of this application. Therefore, all equivalent transformations and modifications made within the scope of the claims of this application should fall within the coverage of the claims of this application.

Claims

1. A lidar based on a non-mechanical solid-state light source, characterized in that, The lidar includes a transmitting array, which includes multiple subarrays, each of which includes a phase modulation unit and a transmitting antenna unit. The scanning area of ​​the transmitting array is divided into multiple sub-regions, and the sub-arrays and the sub-regions correspond one-to-one. The sub-arrays are used to scan the corresponding sub-regions.

2. The lidar based on a non-mechanical solid-state light source as described in claim 1, characterized in that, The emission array includes a light source module and an optical phased array module. The light emitted by the light source module is phase-modulated by the optical phased array module and then output. The optical phased array module consists of the phase modulation unit of each subarray and the corresponding transmitting antenna unit.

3. The lidar based on a non-mechanical solid-state light source as described in claim 2, characterized in that, When the light source module outputs waveguide light to the optical phased array module, the optical phased array module also includes a beam splitter, and the multiple parallel beams generated by the beam splitter enter the corresponding phase modulation unit through the optical waveguide.

4. The lidar based on a non-mechanical solid-state light source as described in claim 1, characterized in that, When the lidar scans, the subarrays scan simultaneously or at staggered times.

5. The lidar based on a non-mechanical solid-state light source as described in claim 1, characterized in that, The scan pixel array of each of the subarrays is set to the same scan pixel array.

6. The lidar based on a non-mechanical solid-state light source as described in claim 1, characterized in that, The subarray has a variety of different scan pixel arrays.

7. The lidar based on a non-mechanical solid-state light source as described in claim 2, characterized in that, The transmitting array also includes an optical output module, which is located behind the optical phased array module along the optical path.

8. The lidar based on a non-mechanical solid-state light source as described in claim 7, characterized in that, The optical output module includes a liquid crystal polarizing grating, and a linear polarizer is disposed in front of the liquid crystal polarizing grating.

9. The lidar based on a non-mechanical solid-state light source as described in claim 7, characterized in that, The optical output module includes a Bragg volume grating.

10. The lidar based on a non-mechanical solid-state light source as described in any one of claims 7 to 9, characterized in that, The optical output module includes an external lens.

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