Angle detection device and laser radar scanning system

Abstract

The invention provides an angle detection device and a laser radar scanning system, and relates to the field of optical detection, the device is used for detecting the inclination angle of an MEMS micromirror based on a first rotating shaft and a second rotating shaft, and the device comprises a light source; the photoelectric detector matrix comprises N photoelectric detector arrays, the photoelectric detector matrix and the light source are located on the same plane, N is larger than or equal to 4, and the light source is located in the center of the photoelectric detector matrix. Based on the device, angle detection of the MEMS micromirror based on biaxial inclination can be realized, light spot distribution of reflected laser is detected through a detection array formed by a plurality of photoelectric detectors, the response time of a sensor can be shortened so as to realize real-time detection of angle change of the MEMS micromirror, and the photoelectric detectors are arranged in a matrix form, so that the detection accuracy is improved. The MEMS micro-mirror angle detection device is compact in overall structure arrangement and small in occupied space, so that the device can be arranged in a laser radar scanning system more easily, and angle detection can be directly carried out on the MEMS micro-mirror.

Description

Technical Field

[0001] The present application relates to the field of optical detection, and in particular to an angle detection device and a laser radar scanning system. Background Art

[0002] With the development of autonomous driving technology, LiDAR, as an important device in autonomous driving technology, can detect the driving environment. Micro-electro-mechanical system (MEMS) micromirrors are characterized by small size, low power consumption, fast response, and long life, so they are widely used in LiDAR. In order to achieve precise control of MEMS micromirrors, it is necessary to measure the tilt angle of the MEMS micromirrors. However, the detection error of angle detection devices based on piezoresistive feedback, piezoelectric feedback, etc. is large, making it difficult to accurately measure the tilt angle of the MEMS micromirrors. Therefore, how to accurately measure the tilt angle of the MEMS micromirrors in real time is a problem that needs to be solved urgently. Summary of the Invention

[0003] The embodiments of the present application provide an angle detection device and a lidar scanning system, which can decouple the action of detecting the MEMS micromirror based on the dual-axis tilt angle, help avoid the detection error caused by the dual-axis coupling of the MEMS micromirror, thereby increasing the accuracy of the MEMS micromirror tilt angle detection, and can also eliminate the error caused by temperature drift of the detection device.

[0004] In a first aspect, an angle detection device is provided for detecting the tilt angle of a micro-electromechanical system (MEMS) micromirror based on a first rotation axis and a second rotation axis. The device includes: a light source; a photodetector matrix including N photodetector arrays, the photodetector matrix and the light source are located in the same plane, N is greater than or equal to 4, and the light source is located at the center of the photodetector matrix.

[0005] For example, the first rotation axis can be the fast axis of the MEMS micromirror, and the second rotation axis can be the slow axis of the MEMS micromirror. Typically, the fast axis and slow axis of the MEMS micromirror intersect and are perpendicular to each other, allowing the MEMS micromirror to achieve two-dimensional rotation in the horizontal and vertical directions, thereby realizing the two-dimensional laser scanning function of the lidar.

[0006] Based on the above technical solution, it is possible to detect the angle of the MEMS micromirror based on dual-axis tilt. In addition, a detection array composed of multiple photodetectors can detect the spot distribution of the reflected laser, which can speed up the sensor's response time to achieve real-time detection of the MEMS micromirror's angle changes. In addition, the photodetectors are arranged in a matrix form, and the overall structure is compact and occupies little space, making it easier to install the device in a lidar scanning system, thereby directly detecting the angle of the MEMS micromirror.

[0007] In combination with the first aspect, in certain implementations of the first aspect, the photodetector array includes four photodetectors distributed in a 2×2 pattern, and the N photodetector arrays are respectively located around the light source.

[0008] For example, each photodetector array may include 4 photodetectors distributed in a 2×2 (number of rows×number of columns) format.

[0009] For example, the photodetector matrix may further include 8 photodetector arrays. Accordingly, these 8 photodetector arrays may be distributed in a 2×4 pattern.

[0010] Based on the above technical solution, the spot distribution of the reflected laser is detected by a detection array composed of multiple photodetectors, which can speed up the response time of the sensor and realize real-time detection of the angle change of the MEMS micromirror.

[0011] In combination with the first aspect, in certain implementations of the first aspect, the light source is used to emit a light beam to a first surface of the MEMS micromirror, a reflective layer is coated on the first surface of the MEMS micromirror, and the MEMS micromirror is used to reflect the light beam to a photodetector matrix.

[0012] Based on the above technical solution, by performing a coating process on the first surface of the MEMS micromirror to form a reflective layer, the loss of reflected light can be greatly reduced, which helps to increase the light intensity amplitude received by the photodetector matrix, thereby increasing the angular resolution of the device 200.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the light source and the photodetector matrix are located on the same silicon substrate.

[0014] For example, a pad 213 is further provided on the silicon substrate 214 , and the pad 213 is used to connect and energize electronic devices such as the photodetector matrix 212 and the light source 211 .

[0015] Based on the above technical solution, the light source and the photodetector matrix are arranged on the same silicon substrate to form a highly integrated angle detection device. In addition, it is convenient to add other components such as pads, marks, leads, etc. on the silicon substrate, thereby further increasing the integration of the device.

[0016] In combination with the first aspect, in certain implementations of the first aspect, the above-mentioned device also includes a grating cover plate, which includes N grating arrays. The grating cover plate is arranged on the photodetector matrix, and the positions of the N grating arrays correspond one-to-one to the positions of the N photodetector arrays. The stripe direction of the first part of the gratings in the N grating arrays is a first direction, and the stripe direction of the second part of the gratings in the N grating arrays is a second direction. The first direction is parallel to the first rotation axis of the MEMS micromirror, and the second direction is parallel to the second rotation axis of the MEMS micromirror.

[0017] It should be understood that, because the N grating arrays correspond one-to-one to the positions of the N photodetector arrays, the intensity of the light signals received by the N photodetector arrays is also affected by the N grating arrays. This reduces the sensitivity of some photodetectors (e.g., those corresponding to the first portion of the gratings) to changes in the distribution of the detection light spot in the second direction, and also reduces the sensitivity of other photodetectors (e.g., those corresponding to the second portion of the gratings) to changes in the distribution of the detection light spot in the first direction.

[0018] Based on the above technical solution, even if the MEMS micromirror is tilted based on the first rotation axis and the second rotation axis at the same time, under the influence of the grating cover plate on the light spot, it is possible to achieve that a part of the photodetectors in the photodetector matrix is dedicated to detecting the tilt angle of the MEMS micromirror based on the first rotation axis, and the other part of the photodetectors can be dedicated to detecting the tilt angle of the MEMS micromirror based on the second rotation axis, thereby helping to decouple the action of detecting the MEMS micromirror based on the dual-axis tilt angle.

[0019] In combination with the first aspect, in certain implementations of the first aspect, the grating cover plate further includes a lens, the position of the lens corresponding to the position of the light source, and the lens is used to make the spot distribution formed by the light beam emitted by the light source correspond to the stripe direction and stripe shape of the N grating arrays in the grating cover plate.

[0020] Based on the above technical solution, the direction of the light spot stripes formed on the photodetector matrix is made to correspond to the stripe direction of the grating array through a lens, so that the light spot also includes stripe spots parallel to the first direction and stripe spots parallel to the second direction. Then, as the MEMS micromirror tilts based on two axes, the distribution of the stripe spots parallel to the first direction will only change when the MEMS micromirror deflects about the second axis during the deflection process, and the distribution of the light spots parallel to the second direction will only change when the MEMS micromirror deflects about the first axis during the deflection process, thereby avoiding the detection error caused by the dual-axis coupling of the MEMS micromirror, and thereby increasing the accuracy of the MEMS micromirror tilt angle detection.

[0021] In combination with the first aspect, in certain implementations of the first aspect, a first spacing exists between a first grating in the first partial grating and a second grating adjacent to the first grating in the second direction, and stripes of the first grating and stripes of a third grating adjacent to the first grating in the first direction are staggered by a second spacing in the second direction; a first spacing exists between a fourth grating in the second partial grating and a fifth grating adjacent to the fourth grating in the first direction, and stripes of the fourth grating and stripes of a sixth grating adjacent to the fourth grating in the second direction are staggered by a second spacing in the first direction, wherein the first spacing is (n+(1 / 4))d, or (n+(1 / 2))d, and the second spacing is m×d, where n and m are integers, and d is the stripe width of the grating.

[0022] For example, due to the specific spacing between the gratings, when the photodetectors corresponding to these gratings receive light spots that are periodically shifted as the MEMS micromirror rotates periodically, there is a certain phase difference in the signal outputs of these photodetectors in the same period.

[0023] For example, assuming that the photodetector has a temperature drift error, the output signals of the photodetectors corresponding to the first grating and the third grating in the same period both have a temperature drift error. Then, the two output signal results are subtracted, and the new output signal result obtained is the result of eliminating the temperature drift error.

[0024] Based on the above technical solution, a specific grating cover plate design is used to align the spot distribution shape of the emitted laser light with the grating distribution of the grating cover plate, and phase differences are generated in the outputs of the individual photosensors in the photodetector array. Based on these phase differences in the outputs of the individual photosensors, corresponding calculations can be performed on the output results of each photoelectric sensor to eliminate the influence of errors caused by temperature drift in the angle detection device. Furthermore, since the grating will block the light spot to a certain extent, the light spot processed by the grating cover plate will have more spot characteristics, thereby helping to make the output characteristics of the photodetector array more distinct. Based on these output characteristics, the tilt angle of the MEMS micromirror can be obtained.

[0025] In combination with the first aspect, in some implementations of the first aspect, a light shielding portion is provided on a side surface of the lens, and the light shielding portion is used to shield interfering light incident from the side surface of the lens.

[0026] For example, the above-mentioned interference light can be a kind of ambient light, which includes light beams from other light sources, or light beams from inside the lidar system. For example, due to errors in the optical module, part of the laser emitted by the lidar is retained in the lidar system and is not emitted, and is thus received by the detector inside the lidar in the form of interference light.

[0027] Based on the above technical solution, the shading portion can block ambient light from the side, thereby reducing measurement errors.

[0028] In combination with the first aspect, in certain implementations of the first aspect, the above-mentioned photodetector matrix is used to collect the light beam reflected by the MEMS micromirror and output N collection results, and there is a mapping relationship between the N collection results and the tilt angle of the MEMS micromirror.

[0029] For example, the above mapping relationship may also be expressed in the form of a mathematical formula, or in the form of a mapping table.

[0030] Based on the above technical solution, the tilt angle of the MEMS micromirror can be determined through the output of the photodetector matrix.

[0031] In combination with the first aspect, in some implementations of the first aspect, the light source is a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED), and the photodetector is a photodiode (PD).

[0032] Based on the above technical solution, using LCSEL as the light source can reduce the impact of temperature on the luminous performance of the light source, and using PD as the photodetector can increase the data acquisition efficiency of the photodetector matrix based on the fast response characteristics of PD.

[0033] In a second aspect, a laser radar scanning system is provided, which includes: a micro-electromechanical system MEMS micromirror device, including a MEMS micromirror, a first rotation axis and a second rotation axis, and the MEMS micromirror is tilted based on the first rotation axis and the second rotation axis; an angle detection device, arranged below the MEMS micromirror device and opposite to the first surface of the MEMS micromirror, the angle detection device including: a light source and a photodetector matrix, wherein the photodetector matrix includes N photodetector arrays, the photodetector matrix and the light source are located in the same plane, N is greater than or equal to 4, and the light source is located at the center of the photodetector matrix.

[0034] In combination with the second aspect, in some implementations of the second aspect, the photodetector array includes 4 photodetectors distributed in a 2×2 pattern, and the N photodetector arrays are respectively located around the light source.

[0035] In combination with the second aspect, in certain implementations of the second aspect, the light source is used to emit a light beam to a first surface of the MEMS micromirror, a reflective layer is coated on the first surface of the MEMS micromirror, and the MEMS micromirror is used to reflect the light beam to a photodetector matrix.

[0036] In combination with the second aspect, in certain implementations of the second aspect, the light source and the photodetector matrix are located on the same silicon substrate.

[0037] In combination with the second aspect, in certain implementations of the second aspect, the angle detection device further includes a grating cover plate, the grating cover plate includes N grating arrays, the grating cover plate is arranged on the photodetector matrix, the positions of the N grating arrays correspond one-to-one to the positions of the N photodetector arrays, the stripe direction of the first part of the gratings in the N grating arrays is a first direction, and the stripe direction of the second part of the gratings in the N grating arrays is a second direction, the first direction is parallel to the first rotation axis of the MEMS micromirror, and the second direction is parallel to the second rotation axis of the MEMS micromirror.

[0038] In combination with the second aspect, in certain implementations of the second aspect, the grating cover plate further includes a lens, the position of the lens corresponds to the position of the light source, and the lens is used to make the spot distribution formed by the light beam emitted by the light source correspond to the stripe direction and stripe shape of the N grating arrays in the grating cover plate.

[0039] In combination with the second aspect, in certain implementations of the second aspect, a first spacing exists between the first grating in the first portion of the grating and a second grating adjacent to the first grating in the second direction, and the stripes of the first grating and the stripes of a third grating adjacent to the first grating in the first direction are staggered by a second spacing in the second direction; a first spacing exists between the fourth grating in the second portion of the grating and a fifth grating adjacent to the fourth grating in the first direction, and the stripes of the fourth grating and the stripes of a sixth grating adjacent to the fourth grating in the second direction are staggered by a second spacing in the first direction, the first spacing is (n+(1 / 4))d, or (n+(1 / 2))d, and the second spacing is m×d, where n and m are integers, and d is the stripe width of the grating.

[0040] In combination with the second aspect, in some implementations of the second aspect, a light shielding portion is provided on a side surface of the lens, and the light shielding portion is used to shield interference light incident from the side surface of the lens.

[0041] In combination with the second aspect, in certain implementations of the second aspect, the photodetector matrix is used to collect the light beam reflected by the MEMS micromirror and output N collection results, and there is a mapping relationship between the N collection results and the tilt angle of the MEMS micromirror.

[0042] In combination with the second aspect, in some implementations of the second aspect, the light source is a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED), and the photodetector is a photodiode (PD).

[0043] In combination with the second aspect, in certain implementations of the second aspect, the above-mentioned system also includes: a driving device, arranged below the angle detection device, the driving device being used to drive the MEMS micromirror to tilt based on the first rotation axis and the second rotation axis; a supporting device being used to support the MEMS micromirror device, the angle detection device and the driving device.

[0044] In a third aspect, a vehicle is proposed, which includes a lidar scanning system as in any possible implementation of the second aspect, or the lidar scanning system of the vehicle includes an angle detection device as in any possible implementation of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a functional schematic block diagram of a vehicle 100 provided in an embodiment of the present application;

[0046] Figure 2 is a schematic diagram of an angle detection device 200 proposed in an embodiment of the present application;

[0047] Figure 3 is a schematic diagram of an optical lens assembly 215 proposed in an embodiment of the present application;

[0048] Figure 4 is a schematic diagram of an optical lens assembly 215 proposed in an embodiment of the present application;

[0049] Figure 5 2 is a schematic diagram of the angle detection principle of the device 200 proposed in an embodiment of the present application;

[0050] Figure 6 2 is a schematic diagram of a design of a silicon substrate 214 proposed in an embodiment of the present application;

[0051] Figure 7 This is a schematic diagram of a PCB design proposed in an embodiment of the present application;

[0052] Figure 8 is a schematic diagram of an angle detection device 300 proposed in an embodiment of the present application;

[0053] Figure 9 is a schematic diagram of a grating cover plate 270 proposed in an embodiment of the present application;

[0054] Figure 10 This is a schematic diagram of laser transmission and reception based on the grating cover plate 270 proposed in an embodiment of the present application;

[0055] Figure 11 This is a schematic diagram of a striped light spot formed based on the light shielding portion of a lens, as proposed in an embodiment of the present application;

[0056] Figure 12This is a schematic diagram of the distribution of grating strips proposed in an embodiment of the present application;

[0057] Figure 13 This is a schematic diagram of the light spot distribution on the PD surface within one MEMS micromirror rotation cycle proposed in an embodiment of the present application;

[0058] Figure 14 This is a schematic diagram of a PD output signal proposed in an embodiment of the present application;

[0059] Figure 15 These are the sine wave signals and square wave signals of PD1-3 and PD2-4 proposed in the embodiments of the present application;

[0060] Figure 16 This is a simulation experiment result diagram of the output of a photodetector matrix proposed in an embodiment of the present application;

[0061] Figure 17 This is a simulation experiment result diagram of the intensity variation of the light spot on the surface of a photodetector matrix proposed in an embodiment of the present application;

[0062] Figure 18 1800 is a flowchart of a method for determining calibration parameters proposed in an embodiment of the present application;

[0063] Figure 19 1900 is a flowchart of a method 1900 for calculating an angle based on calibration parameters, as proposed in an embodiment of the present application;

[0064] Figure 20 is a schematic diagram of an integrated angle detection device proposed in an embodiment of the present application;

[0065] Figure 21 21 is a schematic diagram of a laser radar scanning system 2100 proposed in an embodiment of the present application;

[0066] Figure 22 1 is a schematic diagram of a MEMS micromirror device 10 proposed in an embodiment of the present application;

[0067] Figure 23 Schematic diagram of the structure of a driving device 30 proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0069] In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in this article is a kind of association relationship that describes associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In this application, "at least one" refers to one or more, and "more than one" refers to two or more. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0070] In the embodiments of this application, prefixes such as "first" and "second" are used only to distinguish different description objects and have no limiting effect on the position, order, priority, quantity, or content of the described objects. The use of prefixes such as ordinal numbers in the embodiments of this application to distinguish description objects does not constitute a limitation on the described objects. For a statement of the described objects, please refer to the description in the context of the claims or embodiments, and the use of such prefixes should not constitute an unnecessary limitation.

[0071] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0072] Figure 1 It is a functional schematic block diagram of a vehicle 100 provided in an embodiment of the present application.

[0073] The vehicle 100 may include a perception system 120, a display device 130, and a computing platform 150. The perception system 120 may include several sensors for sensing information about the environment surrounding the vehicle 100. For example, the perception system 120 may include a positioning system, which may be a global positioning system (GPS), a Beidou system or other positioning systems, an inertial measurement unit (IMU), a laser radar, a millimeter-wave radar, an ultrasonic radar, and a camera.

[0074] Some or all functions of the vehicle 100 may be controlled by a computing platform 150. The computing platform 150 may include processors 151 to 15n (n is a positive integer). A processor is a circuit capable of processing signals. In one implementation, the processor may be a circuit capable of reading and executing instructions, such as a central processing unit (CPU), a microprocessor, a graphics processing unit (GPU) (which can be understood as a microprocessor), or a digital signal processor (DSP). In another implementation, the processor may implement certain functions through the logical relationships of a hardware circuit. The logical relationships of the hardware circuit may be fixed or reconfigurable. For example, the processor may be a hardware circuit implemented by an application-specific integrated circuit (ASIC) or a programmable logic device (PLD), such as a field programmable gate array (FPGA). In a reconfigurable hardware circuit, the process of the processor loading a configuration file to implement the hardware circuit configuration can be understood as the process of the processor loading instructions to implement the functions of some or all of the above units. In addition, it can also be a hardware circuit designed for artificial intelligence, which can be understood as an ASIC, such as a neural network processing unit (NPU), a tensor processing unit (TPU), a deep learning processing unit (DPU), etc. In addition, the computing platform 150 can also include a memory for storing instructions, and some or all of the processors 151 to 15n can call the instructions in the memory to implement the corresponding functions described in the embodiments of the present application.

[0075] The vehicles involved in this application may include road vehicles, industrial equipment, agricultural equipment, or entertainment equipment, etc. For example, the vehicle may include an unmanned vehicle, which is a vehicle in a broad sense, and may be a vehicle (such as a commercial vehicle, a passenger car, a motorcycle, a flying car, a train, etc.), industrial equipment (such as a robot based on a machine vision system), an industrial vehicle (such as a forklift, a trailer, a tractor, etc.), an engineering vehicle (such as an excavator, a bulldozer, a crane, etc.), agricultural equipment (such as a lawn mower, a harvester, etc.), amusement equipment, a toy vehicle, etc. The embodiments of this application do not specifically limit the type of vehicle. In addition, the application objects of the embodiments of this application are not limited to vehicles, but can also be extended to water vehicles or air vehicles, such as unmanned yachts and drones.

[0076] MEMS, also known as micro-electromechanical systems or micro-electromechanical systems, refers to micro-devices or systems that utilize traditional semiconductor processes and materials to integrate micro-sensors, micro-actuators, micro-mechanical structures, signal processing and control circuits, high-performance electronic integrated devices, interfaces, communications, and power supplies. A MEMS micromirror is a vibrating mirror manufactured using standard MEMS manufacturing processes.

[0077] It should be understood that the MEMS micromirror described in this application can also be called a MEMS lens, a MEMS rotating mirror, a MEMS vibrating mirror, a MEMS micro-vibrating mirror, etc., and the embodiments of this application do not limit this.

[0078] LiDAR systems used in autonomous vehicles typically use MEMS mirrors for laser scanning to acquire information about the vehicle's surroundings. LiDAR imaging quality is a key indicator of LiDAR's competitiveness, and this quality is inextricably linked to the precise control of the MEMS mirror's rotation. Therefore, closed-loop control can be used to improve the vibration accuracy of the MEMS mirror. However, high-precision closed-loop control relies on high-precision detection methods. Therefore, precise control of the MEMS mirror requires accurate measurement of its tilt angle. Because the vibration amplitude and phase of a MEMS mirror vary with voltage, atmospheric humidity, and temperature, accurate operation requires the real-time status of the mirror. For example, a processor can monitor the real-time tilt angle of the MEMS mirror to achieve real-time control of its rotation angle.

[0079] In addition, MEMS micromirrors can also be used in projectors, laser processing equipment, etc.

[0080] At present, the angle detection of MEMS micromirrors can be achieved through the following two methods.

[0081] Method 1: Piezoresistive detection-based method, that is, by integrating a piezoresistive sensor on or around the cantilever beam of the MEMS micromirror, as the micromirror deflects, the cantilever beam deforms, causing the piezoresistive sensor to generate a signal, which is then used to analyze the rotation angle of the micromirror.

[0082] Method 2: Based on the piezoelectric detection method, that is, by integrating the piezoelectric sensor on or around the cantilever beam of the MEMS micromirror, as the micromirror deflects, the cantilever beam deforms, causing the output of the piezoelectric sensor to change, and the rotation angle of the micromirror is analyzed by the change in the form of the signal.

[0083] However, both Method 1 and Method 2 require processing on the basis of the MEMS micromirror product. The processing is complicated, which increases the difficulty of manufacturing the MEMS micromirror. In addition, the sensing accuracy of the piezoresistive sensor or the piezoelectric sensor is affected by temperature, for example, there is a problem of temperature drift. In addition, since the MEMS micromirror is deflected based on two rotating axes (fast axis and slow axis), and the piezoresistive sensor or the piezoelectric sensor measures the deflection of the two rotating axes at the same time, there is a coupling error caused by the dual-axis deflection of the MEMS micromirror. Among them, temperature drift refers to the change in semiconductor device parameters caused by temperature changes. It is the main reason for the zero-point drift phenomenon of the sensor detection element. Therefore, zero-point drift is usually also called temperature drift, or simply temperature drift. In addition, the piezoelectric sensor or piezoresistive sensor obtains the pressure value of the MEMS micromirror's tilt on the beam, and indirectly calculates the MEMS micromirror's tilt angle through this pressure value. This method has poor accuracy and poor sensitivity to the MEMS micromirror's tilt detection, and responds slowly. Moreover, when considering the errors introduced by temperature drift and dual-axis coupling, it is difficult for the above methods 1 and 2 to achieve real-time and accurate measurement of the MEMS micromirror's tilt angle.

[0084] It can be seen that the angle detection accuracy of the above methods 1 and 2 is poor, and they cannot eliminate the error caused by temperature drift and dual-axis deflection coupling. In view of this, the embodiments of the present application propose an angle detection device and a lidar scanning system. By using a specially designed grating cover and laser transceiver, the measurement of dual-axis deflection is decoupled, and the measurement error caused by temperature drift can be eliminated, which can improve the accuracy of MEMS micromirror deflection angle detection.

[0085] Figure 2 Figure 2 is a schematic diagram of an angle detection device 200 proposed in an embodiment of the present application. This device is used to detect the tilt angle of a MEMS micromirror about a first rotation axis and a second rotation axis. It should be understood that the tilt angle of a MEMS micromirror can also be referred to as a rotation angle or a rotation angle, which is not limited in this embodiment of the present application.

[0086] For example, the first rotation axis can be the fast axis of the MEMS micromirror, and the second rotation axis can be the slow axis of the MEMS micromirror. Typically, the fast axis and slow axis of the MEMS micromirror intersect and are perpendicular to each other, allowing the MEMS micromirror to achieve two-dimensional rotation in the horizontal and vertical directions, thereby realizing the two-dimensional laser scanning function of the lidar.

[0087] The apparatus 200 includes:

[0088] Light source 211;

[0089] The photodetector matrix 212 includes N photodetector arrays 2121 , and the photodetector matrix 212 and the light source 211 are located in the same plane, where N is greater than or equal to 4, and the light source 211 is located at the center of the photodetector matrix.

[0090] In some possible embodiments, the photodetector array 2121 may include four photodetectors distributed in a 2×2 (number of rows × number of columns) pattern, with the N photodetector arrays 2121 positioned around the light source 212. For example, if the photodetector matrix includes four photodetector arrays 2121, these four photodetector arrays 2121 are located at the upper right, upper left, lower right, and lower left of the light source 212, respectively. In other words, the four photodetector arrays 2121 included in the photodetector matrix 212 are also distributed in a 2×2 pattern. Of course, the photodetector array 2121 may also include other numbers of photodetectors. For example, if the photodetector matrix 212 includes two photodetectors distributed in a 2×1 pattern, the photodetector matrix 212 may include eight photodetector arrays 2121. Accordingly, these eight photodetector arrays 2121 may be distributed in a 2×4 pattern. And so on.

[0091] It should be understood that the distribution form of the photodetector matrix 212 is the form proposed in the above example because the shape of the MEMS micromirror is a regular rectangle, and the photodetectors are distributed in a matrix form, which is more suitable for detecting the tilt angle of the MEMS micromirror.

[0092] Based on the above technical solution, it is possible to detect the angle of the MEMS micromirror based on dual-axis tilt. Furthermore, by detecting the spot distribution of the reflected laser light through a detection array composed of multiple photodetectors, the sensor's response time can be accelerated, enabling real-time detection of the MEMS micromirror's angle change. Furthermore, the device 200 directly calculates the MEMS micromirror's tilt angle by collecting the intensity of the light beam reflected by the MEMS micromirror. This solution is more accurate than solutions that detect the MEMS micromirror's tilt angle based on piezoresistive or piezoelectric sensors. Furthermore, the overall structure of the photodetector matrix is compact and occupies little space, making the device 200 easier to install in a laser radar scanning system, thereby enabling direct angle detection of the MEMS micromirror.

[0093] In some possible embodiments, the light source 211 is configured to emit laser light. For example, the light source 211 may be an LED. However, considering that the light emission characteristics of an LED are easily affected by temperature, i.e., the higher the temperature, the lower the intensity of the laser light emitted by the LED. Therefore, a VCSEL may be used as the light source 211 of the device 200 to reduce the impact of temperature on the light emission performance of the light source 211.

[0094] In some possible embodiments, the light source 211 is configured to emit a light beam toward a first surface of the MEMS micromirror. The first surface of the MEMS micromirror is coated with a reflective layer, and the MEMS micromirror is configured to reflect the light beam toward the photodetector matrix 212. That is, the light beam emitted by the light source 211 is reflected by the first surface of the MEMS micromirror coated with the reflective layer and can then be received by the photodetector matrix 212. The first surface of the MEMS micromirror is opposite to the plane where the light source 211 and the photodetector matrix 212 are located.

[0095] For example, when the light source 211 is a VCSEL, the light beam is a laser beam.

[0096] Based on the above technical solution, by performing a coating process on the first surface of the MEMS micromirror to form a reflective layer, the loss of reflected light can be greatly reduced, which helps to increase the light intensity amplitude received by the photodetector matrix, thereby increasing the angular resolution of the device 200.

[0097] In some possible embodiments, the photodetector may be a photodiode (PD). Therefore, the photodetector matrix may also be referred to as a PD matrix, and the photodetector array 2121 may also be referred to as a PD array. It should be noted that a photodetector is also called a photodetector, and is usually referred to as a PD. However, the photodiode proposed in the embodiments of the present application may also be referred to as a PD. To avoid confusion, it is stated that the PD mentioned in the embodiments of the present application is used to specifically refer to a photodiode.

[0098] Based on the above technical solution, PD has the characteristic of fast response speed, and the photodetector matrix includes multiple PDs, so that based on the photodetector matrix, more detection data can be quickly obtained for angle detection, so that the angle detection device responds quickly.

[0099] It should be understood that the angle detection device proposed in the embodiments of the present application is not limited to detecting the tilt angle of the MEMS micromirror, but can also detect the tilt angle of other objects to be measured. In addition, based on the design concept of the angle detection device of the present application, when the object to be measured is tilted along only one axis, the photodetector matrix 212 can be adjusted to a row matrix or a column matrix accordingly, thereby realizing the detection of the tilt angle of the object to be measured.

[0100] In some possible embodiments, when the size of the object to be measured is large, the number of rows and / or columns of the photodetector matrix can be adaptively expanded, and the number of photodetectors included in the photodetector array 2121 can be increased, and vice versa; when the shape of the object to be measured is other shapes, such as a rhombus, the distribution form of the photodetector array 2121 can also be adaptively changed, as can the distribution form of each photodetector in the photodetector array 2121, for example, all adjusted to a rhombus distribution.

[0101] In some possible embodiments, the light source 211 and the photodetector matrix 212 can be deployed on the same silicon substrate 214. Based on the device structure proposed in the above embodiment, the light source 211 can be located at the center of the silicon substrate 214. The light source 211 uses the above VCSEL so that the laser emission direction of the light source 211 is perpendicular to the silicon substrate 214 and upward. The N photodetector arrays are respectively located around the light source 211. For example, referring to Figure 2 As shown, the light source 211 is located at the center of the photodetector matrix 212. In addition, a pad 213 is provided on the silicon substrate 214. The pad 213 is used to connect and energize electronic devices such as the photodetector matrix 212 and the light source 211.

[0102] In some possible embodiments, the silicon substrate 214 may be made of silicon, ceramic or other materials.

[0103] Based on the above technical solution, the light source 211 and the photodetector matrix 212 are arranged on the same silicon substrate 214 to form a highly integrated angle detection device. In addition, other components such as pads, marks, leads, etc. can be easily added on the silicon substrate 214, thereby further increasing the integration of the device.

[0104] In some possible embodiments, the device 200 further includes an optical lens assembly 215 .

[0105] Figure 3 FIG. 2 is a schematic diagram of an optical lens assembly 215 proposed in an embodiment of the present application.

[0106] The optical lens assembly 215 includes a lens 221 and a filter film 222. The lens 221 is positioned relative to the light source 211, allowing the light beam to be emitted through the lens 221 and shaping the light beam, for example, expanding the light beam angle. The filter film 222 covers the sides of the optical lens assembly 215 to shield side light from the sides of the light source 211, thereby preventing errors caused by side light on angle detection.

[0107] In some possible embodiments, the lens 221 is a divergent lens, which is used to amplify the divergence angle of the light beam emitted by the light source 211 to increase the detection range of the device 200 and make the laser Gaussian distributed to form a Gaussian spot. The characteristic of this spot is that the central light intensity is the largest and the light intensity gradually decreases along the radial direction. The light beam with this characteristic is reflected by the MEMS micromirror and received by the photodetector matrix 212, so that the tilt angle of the MEMS micromirror can be solved according to the distribution of the signal output intensity of each photodetector in the photodetector matrix 212.

[0108] It should be understood that, taking the light source 211 as a VCSEL as an example, the laser emitted by the light source 211 is usually in a beam form, so after the lens 221 is expanded, the emission angle of the laser beam will be further diffused. Assuming that the lens 221 does not have a laser angle expansion function, the laser beam emitted by the lens 221 can cover a first range. Since the laser beam is usually narrow, it may be difficult for the laser beam to cover the entire MEMS micromirror, making it difficult to detect the overall tilt state of the MEMS micromirror. Then, if the lens 221 has a laser angle expansion function, the laser beam emitted by the lens 221 can cover a second range, which is larger than the first range, thereby helping to cover the entire MEMS micromirror with the laser beam.

[0109] Based on the above technical solution, the specially structured optical lens assembly 215 can diverge the light beam, thereby increasing the detection range of device 200 and ensuring that the intensity distribution of the light spot formed on the photodetector matrix 212 satisfies a Gaussian distribution. This allows the tilt angle of the MEMS micromirror to be calculated based on the distribution of the signal output intensities of each photodetector in the photodetector matrix 212. Furthermore, the filter film of optical lens assembly 215 blocks ambient light from the side, reducing measurement errors.

[0110] Figure 4 Schematic diagram of the deployment position of the angle detection device 200 proposed in the embodiment of the present application. The device 200 is set in the laser scanner of the laser radar, and the laser scanner performs laser scanning through a MEMS micromirror.

[0111] refer to Figure 4 As shown, the device 200 can be placed behind a MEMS mirror. Specifically, the light source 211 of the device 200 can emit a light beam perpendicularly toward the bottom surface of the MEMS mirror (or the back of the MEMS mirror). The light beam is reflected by the MEMS mirror onto the photodetector matrix 212. Based on the signal strength output by each photodetector, high-precision deflection angle detection of the MEMS mirror can be achieved. The angle detection principle of the device 200 is described below.

[0112] Figure 5 This is a schematic diagram of the angle detection principle of the device 200 proposed in the embodiment of the present application. The schematic diagram uses the light source 211 as a VCSEL and the photodetector as a PD ( Figure 5 It is a front view, showing only two PDs for illustration, and the number of PDs is not limited), and the MEMS micromirror is described based on the fast axis tilt as an example.

[0113] refer to Figure 5 As shown in the figure, when the MEMS micromirror is not tilted, the MEMS micromirror is parallel to the plane where the device 200 is located. The VCSEL emits laser light toward the back of the MEMS micromirror (z-axis direction), and PD1 and PD2 on the same side of the VCSEL receive the laser light reflected back by the MEMS micromirror (the laser light propagation path is the dotted arrow). The spot corresponding to the laser light emitted by the VCSEL is the above-mentioned Gaussian spot. When the MEMS micromirror angle deflects along the fast axis, the MEMS micromirror is not parallel to the plane where the device 200 is located, and the VCSEL emits laser light toward the back of the MEMS micromirror. PD1 and PD2 on the same side of the VCSEL receive the laser light reflected back by the MEMS micromirror (the laser light propagation path is the solid arrow). It can be seen that compared with before the MEMS micromirror tilted, the position of the spot has changed, and the laser light intensity received by PD1 and PD2 is affected by this. Therefore, the tilt angle of the MEMS micromirror can be inferred based on the outputs of PD1 and PD2. In other words, there is a mapping relationship between the output of the photodetector matrix 212 and the tilt angle of the MEMS micromirror.

[0114] It should be understood that Figure 5 Only the angle detection of the MEMS micromirror based on the fast axis tilt is shown. When the angle detection of the MEMS micromirror based on the fast axis and slow axis tilt is performed, the tilt angle of the MEMS micromirror needs to be detected through a two-dimensionally distributed PD array. The detection principle is similar to the above description and will not be repeated here.

[0115] Figure 6 Schematic diagram of a silicon substrate 214 proposed in an embodiment of the present application.

[0116] refer to Figure 6As shown, the upper surface of the silicon substrate 214 is deposited or laser etched with alignment marks, leads, and pads 213 for the light source 211 and the photodetector matrix 212. The alignment marks provide a reference for the packaging of the light source 211 and the photodetector. Leads are arranged below the light source 211 and the photodetector and connected to the pads 213. Since the cathodes of the light source 211 and the photodetector are located on the bottom surface, the light source 211 and the photodetector can be bonded to the silicon substrate 214 using conductive silver glue and connected to the pads 213. The anodes of the photodetector and the light source 211 can be connected to the pads 213 by wire bonding.

[0117] In some possible embodiments, the device 200 further includes a printed circuit board (PCB), on which the silicon substrate 214 and all components deployed on the silicon substrate 214 are carried.

[0118] Figure 7 This is a schematic diagram of a PCB design proposed in an embodiment of the present application.

[0119] refer to Figure 7 As shown, the PCB is also provided with amplifiers. The amplifiers (220, 230, 240) mainly form a transimpedance amplification circuit, an inverting circuit, and a follower circuit of the sensor output signal, thereby realizing analog amplification of the output signal.

[0120] In addition, the PCB is also provided with a power supply module 250 and a flexible cable interface 260. After the above signal is processed by the device 200 and the amplifiers (220, 230, 240), it is finally connected to the external circuit board through the flexible cable interface 260 to output the result.

[0121] Based on the above technical solution, the device 200 is integrated, and the detection elements are all carried on the PCB, so that the device 200 can be powered on and used. In addition, the device 200 is small in size and can be easily installed in the Lidar.

[0122] Figure 8 3 is a schematic diagram of an angle detection device 300 proposed in an embodiment of the present application.

[0123] Similar to angle detection device 200, angle detection device 300 also includes a light source 211 and a photodetector matrix 212. The photodetector matrix 212 includes N photodetector arrays 2121. The photodetector matrix 212 and the light source 211 are located in the same plane, where N is greater than or equal to 4. Furthermore, device 300 also includes a grating cover plate 270, which includes N grating arrays 272. The grating cover plate 270 is disposed above the photodetector matrix 212, with the positions of the N grating arrays 272 corresponding one-to-one with the positions of the N photodetector arrays 2121. The stripes of the first portion of the N grating arrays 272 are oriented in a first direction, while the stripes of the second portion of the N grating arrays 272 are oriented in a second direction. The first direction is parallel to the first rotation axis of the MEMS micromirror, and the second direction is parallel to the second rotation axis of the N photodetector arrays 2121.

[0124] It should be understood that the light source 211 and the photodetector matrix 212 in the device 200 and the device 300 are the same, so for the corresponding extended description of the light source 211 and the photodetector matrix 212 in the device 300, please refer to the aforementioned corresponding embodiments and will not be repeated here.

[0125] For example, the grating in the embodiment of the present application is presented in the form of a rectangular grid, and each grid is composed of multiple grating stripes. The grating stripes in the embodiment of the present application can also be called grating bars, and the embodiment of the present application does not limit the names of grating stripes with equivalent meanings.

[0126] It should be understood that the grating in the embodiment of the present application is an optical element composed of a series of equidistant parallel grating bars (or stripes), and the stripe width of the grating is equal to the width of the gap between the stripes. However, the embodiment of the present application does not limit the distance between the grating stripes, the stripe width and the width of the gap between the stripes.

[0127] In some possible embodiments, the grating cover plate 270 further includes a lens 271, which may be the lens 221 in the device 200. Similar to the previous embodiment, the lens 271 may be a diverging lens, configured to amplify the divergence angle of the light beam emitted by the light source 211, thereby increasing the detection range of the device 300 and imparting a Gaussian distribution to the laser light to form a Gaussian light spot. This light spot is characterized by a maximum light intensity at the center and a gradually decreasing light intensity along the radial direction. The light beam with this characteristic is reflected by the MEMS micromirror and received by the photodetector matrix 212, so that the tilt angle of the MEMS micromirror can be calculated based on the distribution of the signal output intensities of the individual photodetectors in the photodetector matrix 212.

[0128] In some possible embodiments, a first spacing exists between a first grating in the first portion of gratings and a second grating adjacent to the first grating in the second direction, and stripes of the first grating and stripes of a third grating adjacent to the first grating in the first direction are staggered by a second spacing in the second direction; a first spacing exists between a fourth grating in the second portion of gratings and a fifth grating adjacent to the fourth grating in the first direction, and stripes of the fourth grating and stripes of a sixth grating adjacent to the fourth grating in the second direction are staggered by a second spacing in the first direction.

[0129] In some possible embodiments, the first spacing is (n+1 / 4)d, or (n+1 / 2)d, and the second spacing is m×d, where n and m are integers, and d is the stripe width of the grating.

[0130] Figure 9 Schematic diagram of a grating cover plate 270 proposed in an embodiment of the present application.

[0131] refer to Figure 9 As shown, it is assumed that the photodetector matrix 212 includes four photodetector arrays 2121, and each photodetector array 2121 includes photodetectors arranged in a 2×2 pattern. Correspondingly, the grating cover plate 270 also includes four grating arrays 272. Corresponding to the photodetector arrangement of the photodetectors in the photodetector matrix 212, each grating array 272 also includes four gratings arranged in a 2×2 pattern. These four grating stripes are identical. The four grating arrays 272 are distributed in the upper right, upper left, lower left, and lower right of the grating cover plate 270. In this order of description, these four grating arrays can be referred to as the first grating array, the second grating array, the third grating array, and the fourth grating array. The stripes of the first and fourth grating arrays are horizontal and belong to the first grating portion described above, while the stripes of the second and fourth grating arrays are vertical and belong to the second grating portion described above.

[0132] It should be understood that while the stripes of each grating within each grating array are identical, the placement of the stripes within each grating is not aligned. Taking the first grating array as an example, there is a certain vertical deviation between the placement of the grating stripes located in the upper left and the upper right. Based on the aforementioned embodiments, this deviation is equal to one stripe width. Similarly, there is also a certain horizontal deviation between the placement of the grating stripes located in the lower left and the lower right of the first grating array. This is to enhance the spot distribution characteristics of the laser spot formed after screening by the grating cover plate 270. This characteristic can be used to analyze the tilt angle of the measured object and to address the errors caused by zero-point drift. The calculation principle is detailed in the corresponding description of the subsequent embodiments.

[0133] The grating cover plate 270 is used in scenarios where the tilt angle of a MEMS micromirror is detected. The grating stripes of the first and fourth grating arrays are parallel to the slow axis of the MEMS micromirror, while the grating stripes of the second and third grating arrays are parallel to the fast axis of the MEMS micromirror. Therefore, when the MEMS micromirror is tilted about its block axis, the outputs of the photodetectors corresponding to the second and third grating arrays are significantly affected, while the outputs of the photodetectors corresponding to the first and fourth grating arrays are less affected. Ideally, when the MEMS micromirror is tilted about its slow axis, only the outputs of the photodetectors corresponding to the second and third grating arrays are affected, while the outputs of the photodetectors corresponding to the first and fourth grating arrays are not affected. The same applies vice versa.

[0134] For ease of description, the fast axis of the MEMS micromirror is referred to as the y-axis, the slow axis of the MEMS is referred to as the x-axis, and the light source 211 is a VCSEL. When the MEMS micromirror is tilted about the y-axis, the reflection point of the laser light contacting the MEMS micromirror will shift in the x-axis direction as the MEMS micromirror tilts. Considering that the grating cover plate 270 has a certain thickness, when the laser light passes through the vertical striped grating after the reflection point shift, the side surfaces of the vertical striped grating may have a strong blocking effect on the reflected laser light, causing the light spot distribution formed by the vertical striped grating to change significantly compared to before the MEMS micromirror tilted. When the laser light passes through the horizontal striped grating after the reflection point shift, because the laser light reflection point is shifted in the x-axis direction, the blocking effect of the horizontal striped grating on the reflected laser light is weaker. Therefore, the light spot distribution formed by the horizontal striped grating changes less than that before the MEMS micromirror tilted, or may even remain unchanged. The changes in the light spot distribution can be detected by the photodetector matrix. Based on the output of the photodetector matrix, the tilt of the MEMS micromirror around the y-axis and the corresponding tilt angle can be determined, and vice versa.

[0135] It can be seen that the introduction of the grating cover 270 reduces the sensitivity of some photodetectors (such as the photodetectors corresponding to the first grating array and the fourth grating array) to detecting changes in the distribution of the laser spot in the x-axis direction, and also reduces the sensitivity of other photodetectors (such as the photodetectors corresponding to the second grating array and the third grating array) to detecting changes in the distribution of the laser spot in the y-axis direction.

[0136] Based on the above technical solution, even if the MEMS micromirror is tilted based on the x-axis and y-axis at the same time, under the influence of the grating cover on the light spot, it is possible to realize that a part of the photodetectors in the photodetector matrix is dedicated to detecting the tilt angle of the MEMS micromirror based on the y-axis, and the other part of the photodetectors can be dedicated to detecting the tilt angle of the MEMS micromirror based on the x-axis, thereby decoupling the action of detecting the dual-axis tilt angle of the MEMS micromirror.

[0137] Figure 10 This is a schematic diagram of laser transmission and reception based on the grating cover plate 270 proposed in an embodiment of the present application.

[0138] refer to Figure 10 As shown in (a) in FIG. 1 , the light source 211 emits laser light toward the lens 271 of the grating cover 270 . The laser light is diverged by the lens and irradiates the back of the MEMS micromirror 108 .

[0139] refer to Figure 10 As shown in (b), the laser is reflected from the back (first surface) of the MEMS micromirror 108 and is reflected onto the grating cover plate 270. The grating cover plate 270 filters the reflected light and ultimately projects the filtered laser light onto the photodetectors corresponding to each grating, forming a light spot on the photodetector matrix 212. Due to the effect of the grating cover plate 270, the light spot is partially in the shape of horizontal stripes (parallel to the x-axis of the MEMS micromirror 108) and partially in the shape of vertical stripes (parallel to the y-axis of the MEMS micromirror 108). The photodetector matrix 212 detects the tilt angle of the MEMS micromirror 108 about the y-axis based on the change in the distribution of the horizontal stripes of the light spot to determine a first angle component; and detects the tilt angle of the MEMS micromirror 108 about the x-axis based on the change in the distribution of the vertical stripes of the light spot to determine a second angle component. Based on the first angle component and the second angle component, the tilt angle of the MEMS micromirror 108 based on both axes can be determined.

[0140] Based on the above technical solution, the action of detecting the MEMS micromirror based on the dual-axis tilt angle can be decoupled, which helps to avoid the detection error caused by the dual-axis coupling of the MEMS micromirror, thereby eliminating the detection error caused by the dual-axis coupling of the MEMS micromirror and increasing the accuracy of the MEMS micromirror tilt angle detection.

[0141] In some possible embodiments, the lens 271 is further configured to ensure that the light spot distribution formed by the light beam emitted by the light source 211 corresponds to the stripe directions and stripe shapes of the N grating arrays 272 in the grating cover plate 270. For example, this function can be achieved by providing a corresponding light shielding portion on the lens 271.

[0142] Figure 11This is a schematic diagram of a striped light spot formed based on the action of the lens shading portion proposed in an embodiment of the present application.

[0143] refer to Figure 11 As shown, the spot distribution is similar to Figure 9 The grating stripes of the illustrated grating cover plate 270 are uniformly distributed, forming a square-shaped light spot. The stripes on the left and right sides of the light spot are perpendicular to each other and are equally spaced. The stripes on the two sides are oriented parallel to the fast axis (y-axis) and slow axis (x-axis) of the MEMS mirror, respectively. The vertical stripes on the left side of the light spot can be used to detect the tilt angle of the MEMS mirror about the y-axis, while the horizontal stripes on the right side of the light spot can be used to detect the tilt angle of the MEMS mirror about the x-axis.

[0144] In some possible embodiments, the number of gratings in the first and second grating portions of the grating cover plate 270 is a multiple of 2, such as 8, 16, 32, etc. Furthermore, the number of gratings in the first and second grating portions of the grating cover plate 270 may also be equal.

[0145] The correspondence between the light spot distribution and the stripe directions of the N grating arrays 272 in the grating cover plate 270 means that the gratings included in the N grating arrays are divided into a first portion of gratings and a second portion of gratings, wherein the stripe direction of the first portion of gratings is a first direction, and the stripe direction of the second portion of gratings is a second direction. Then, the light spot formed by the light shielding portion is also stripe-shaped, and the light spot can also be divided into a first portion of light spots and a second portion of light spots according to the stripe direction. wherein, the stripe direction of the first portion of light spots is a first direction, which is the same as the stripe direction of the first portion of gratings, and the stripe direction of the second portion of light spots is a second direction, which is the same as the stripe direction of the second portion of light spots.

[0146] The correspondence between the light spot distribution and the stripe shapes of the N grating arrays 272 in the grating cover plate 270 means that the stripe geometric parameters formed by the light spot (such as the width of the stripe) are equal to the stripe geometric parameters of the grating, and the parameter difference between the stripe geometric parameters formed by the light spot and the stripe geometric parameters of the grating is within a preset difference range.

[0147] Then based on the light shielding part, the light spot formed on the photodetector matrix is also striped. Figure 9 Taking the first grating and the third grating of the first part of the grating in the grating cover plate 270 as an example, the second distance between the stripes of the first grating and the stripes of the third grating in the second direction is 1 stripe width d, and the reference Figure 11As can be seen, the light spot is a complete, continuous straight stripe in the first direction. Therefore, the signal intensity detected by the first photodetector corresponding to the first grating differs from the signal intensity detected by the second photodetector corresponding to the third grating. For example, if both the first and third gratings include three bars, i.e., four light-transmitting openings, then if the first photodetector can detect four complete stripes of light, the second photodetector will not detect the light because the stripes are blocked by the three bars of the third grating.

[0148] It can be seen from this that when the deflection angle of the MEMS micromirror changes periodically, there is a phase difference of π / 2 between the signal light intensity change curve responded by the first photodetector and the signal light intensity change curve responded by the second photodetector. Based on the signal light intensity change characteristics between the photodetectors, the rotation direction and rotation angle of the MEMS micromirror can be calculated, and the detection error caused by temperature drift can be solved. The detailed detection principle and process are detailed in the subsequent embodiments.

[0149] The following describes a detailed example of the principle of measuring the tilt angle of an object by the device 300 proposed in this application.

[0150] This example uses the grating cover 270 reference Figure 9 As shown, the stripe-shaped spot distribution formed by the light source 211 through the lens shading portion is referred to Figure 11 shown.

[0151] Figure 12 : is a schematic diagram of a grating stripe distribution proposed in an embodiment of the present application, wherein the grating stripes can be understood as the grating stripes proposed in the above embodiment.

[0152] Taking the second grating array as an example, the second grating array includes four gratings, denoted as grating 1 (at the upper left position of the second grating array), grating 2 (at the upper right position of the second grating array), grating 3 (at the lower left position of the second grating array), and grating 4 (at the lower right position of the second grating array). Each grating includes multiple vertical bars, each of which has a width d and a length l. The spacing between the multiple bars can also be d, wherein the bars are used to block reflected laser light, and the spacing between the bars is used to transmit reflected laser light. Since the gratings correspond one-to-one to the photodetectors (taking PD as an example), the projection of each grating of the grating cover plate 270 in a direction perpendicular to the PD can cover the corresponding PD.

[0153] In addition, a spacing L may be provided between each grating in the second grating array. The spacing L may be set to a multiple of the grating width d. The multiple may be an integer multiple or a non-integer multiple. Based on the above embodiment, it can be seen that: L = (n + (1 / 4)) d or L = (n + (1 / 2)) d, where n is a positive integer. Figure 12The example in FIG. 1 uses L=(n+(1 / 2))d.

[0154] Based on the above embodiment, it can be seen that the positions of the gratings of the four gratings of the second grating array are not completely aligned. Taking grating 1 and grating 3 of the second grating array as an example, the gratings of grating 3 are staggered by a second spacing in the x-axis direction compared with the gratings of grating 1. Figure 12 As shown, the second spacing may be equal to the grating width d. The gratings of grating 2 and grating 4 are distributed in the same manner.

[0155] Since the MEMS micromirror needs to periodically rotate along two axes during use, the output signals of the four PDs corresponding to the second grating array also exhibit corresponding periodic changes. For ease of description, in this embodiment of the application, the PD corresponding to grating 1 is denoted as PD1, the PD corresponding to grating 2 is denoted as PD2, the PD corresponding to grating 3 is denoted as PD3, and the PD corresponding to grating 4 is denoted as PD4.

[0156] Figure 13 This is a schematic diagram of the light spot distribution on the PD surface within one MEMS micromirror rotation cycle proposed in an embodiment of the present application.

[0157] Figure 13 The figure shows the light spot distribution on the PD surface corresponding to the four gratings of the second grating array. t1 and t4 correspond to the start and end times of the MEMS micromirror rotation cycle, respectively, and the time intervals between t1, t2, t3, and t4 are the same. The PD non-receiving position corresponds to the grating bar position. This position is blocked by the grating bars, resulting in the inability to receive light signals, i.e., no light spot can be formed. The PD receiving position corresponds to the gap position between the grating bars. This position is not blocked by the grating bars, so at least part of the light signal can be received, i.e., at least part of the light spot can be formed.

[0158] At time t1, the bars of grating 1 block part of the light signal, so a partial stripe light spot can be formed at each PD receiving position of PD1, and the light spot is located at the left part of each PD receiving position of PD1; grating 2 does not block the light signal, so a complete stripe light spot can be formed at each receiving position of PD2, and the light spot occupies each PD receiving position of PD2; the bars of grating 3 block part of the light signal, so a partial stripe light spot can be formed at each PD receiving position of PD3, and the light spot is located at the right part of each PD receiving position of PD3; grating 4 completely blocks the light signal, so no stripe light spot can be formed at each receiving position of PD4.

[0159] At time t2, grating 1 does not block the light signal (excluding the blocking of the light signal by the left frame of grating 1), so a complete striped light spot can be formed at each receiving position of PD1, and the light spot occupies each PD receiving position of PD1; the bars of grating 2 block part of the light signal, so a partial striped light spot can be formed at each PD receiving position of PD2, and the light spot is located at the right part of each PD receiving position of PD2; grating 3 completely blocks the light signal, so no striped light spot can be formed at each receiving position of PD3; the bars of grating 4 block part of the light signal, so a partial striped light spot can be formed at each PD receiving position of PD4, and the light spot is located at the left part of each PD receiving position of PD4.

[0160] At time t3, the bars of grating 1 block part of the light signal, so a partial stripe light spot can be formed at each PD receiving position of PD1, and the light spot is located at the right part of each PD receiving position of PD1; grating 2 completely blocks the light signal, so no stripe light spot can be formed at each receiving position of PD2; the bars of grating 3 block part of the light signal, so a partial stripe light spot can be formed at each PD receiving position of PD3, and the light spot is located at the left part of each PD receiving position of PD3; grating 4 does not block the light signal, so a complete stripe light spot can be formed at each receiving position of PD4, and the light spot occupies each PD receiving position of PD4.

[0161] At time t4, grating 1 completely blocks the light signal, so no striped light spot can be formed at each receiving position of PD1; the bars of grating 2 block part of the light signal, so a partial striped light spot can be formed at each PD receiving position of PD2, and the light spot is located at the left part of each PD receiving position of PD2; grating 3 does not block the light signal (excluding the blocking of the light signal by the right frame of grating 3), so a complete striped light spot can be formed at each receiving position of PD3, and the light spot occupies each PD receiving position of PD3; the bars of grating 4 block part of the light signal, so a partial striped light spot can be formed at each PD receiving position of PD4, and the light spot is located at the right part of each PD receiving position of PD4.

[0162] It should be understood that the more complete the light spot formed on the PD, the greater the signal light intensity responded to by the PD, and the greater the voltage of the output signal. From the state of the light spots formed on the surfaces of each PD mentioned above, it can be seen that as the MEMS micromirror rotates periodically, the signal light intensity responded to by each PD also changes periodically, and then the voltage of the output signal of each PD also changes periodically.

[0163] Figure 14 This is a schematic diagram of a PD output signal proposed in an embodiment of the present application.

[0164] refer to Figure 12 and Figure 13 As shown, since there is a deviation of the width d between the gratings 1 and 3 in the x-axis direction, the reference Figure 14 As shown, the phase difference between the output signal images of PD1 and PD3 is π. It should be understood that when the grating distribution position deviation between grating 1 and grating 3 is other values, the phase difference between the output signal images of PD1 and PD3 will also change. The same applies to PD2 and PD4. Therefore, by subtracting the output signals of PD1 and PD3, and subtracting the output signals of PD2 and PD4, and then calculating the rotation angle of the MEMS micromirror based on the output signals obtained by the difference, the error caused by the zero point drift of the device 300 can be eliminated. Since the interval between PD1 and PD2 is L = (n + (1 / 2)) d, the phase difference between the output signals of PD1 and PD2 is π / 2, and the same applies to PD3 and PD4. Then, after the above-mentioned difference operation of the PD output signals, two sinusoidal wave signals PD1-3 and sine wave signals PD2-4 with a phase difference of π / 2 can be obtained.

[0165] Figure 15 These are the sine wave signals and square wave signals of PD1-3 and PD2-4 proposed in the embodiments of this application.

[0166] The above-mentioned sine wave signals PD1-3 and sine wave signals PD2-4 can be converted into square wave signals, and then the rotation direction of the MEMS micromirror can be determined by comparing the rising edge and falling edge of the square wave signals PD1-3 and PD2-4.

[0167] In some possible embodiments, after the sine wave signals PD1 - 3 and sine wave signals PD2 - 4 are acquired, these two signals may be frequency-multiplied and subdivided to improve detection accuracy.

[0168] Figure 16 This is a simulation experiment result diagram of the output of a photodetector matrix proposed in an embodiment of the present application.

[0169] The simulation experiment is based on Figure 9 The grating cover plate 270 and Figure 11 The positions of the gratings in the same grating array in the grating cover plate 270 differ by d / 2. The MEMS micromirror periodically rotates along two axes, and the photodetector matrix 212 receives the reflected laser light and outputs a signal. Figure 15 Only the outputs of the upper right array (denoted as array 1) and the upper left array (denoted as array 2) of the photodetector matrix 212 are shown.

[0170] The output signal of array 1 is used to detect the angle of the MEMS micromirror's rotation based on the x-axis, and the output signal of array 2 is used to detect the angle of the MEMS micromirror's rotation based on the y-axis. In array 1 or array 2, one PD has the strongest output signal, two PDs have medium outputs, and one PD has the weakest output signal, almost zero. These correspond to the intensity states of the light spots received by the four PDs in the same grating area at the same moment, with positions differing by d / 2.

[0171] Based on the output signal results of arrays 1 and 2 at four moments, it can be seen that the output signal intensity of each PD in array 1 has not changed, while the output signal intensity of each PD in array 2 has changed. This means that the MEMS micromirror only tilts along the y-axis during the time periods corresponding to the four moments.

[0172] In addition, the simulation experiment also tested the intensity of the light spot on the surface of array 1.

[0173] Figure 17 This is a simulation experiment result diagram of the change in light spot intensity on the surface of a photodetector matrix proposed in an embodiment of the present application.

[0174] refer to Figure 17 As shown, as the MEMS micromirror rotates, the spot intensity on the surfaces of PD1 to PD4 in array 1 also changes, and there is a phase difference of π / 2 between the signals of the light intensity received on the surfaces of PD1 to PD4, which is consistent with the above simulation experimental results.

[0175] Considering that the output results of the photodetector matrix 212 are different when the MEMS micromirror is at different tilt angles, the output result can be an output matrix. For example, if the photodetector matrix 212 includes a 2×2 array of four PDs, the corresponding output is a 2×2 output matrix. The output corresponding to each array element can be the sum or weighted average of the output signals of the four PDs in the array. Different output matrices correspond to different tilt angles. The mapping relationship between the output results of the photodetector matrix 212 and the tilt angle of the MEMS micromirror can be calibrated through experiments.

[0176] In some possible embodiments, the above mapping relationship may also be expressed in the form of a mathematical formula or in the form of a mapping table, which is not limited in the embodiments of the present application.

[0177] Based on the above technical solution, through the specific design of the grating cover plate 270, the spot distribution shape corresponding to the emitted laser light corresponds to the grating distribution of the grating cover plate 270, and a phase difference exists in the output of each photoelectric sensor of the photodetector array 2121. Based on the phase difference in the output of each photoelectric sensor, corresponding calculation operations can be performed on the output results of each photoelectric sensor to eliminate the error caused by temperature drift in the angle detection device 200. This also helps to make the output characteristics of the photodetector matrix 212 more distinct. Based on this output characteristic, the tilt angle of the MEMS micromirror can be obtained. In addition, since the stripe direction of the light spot formed on the photodetector matrix 212 corresponds to the stripe direction of the grating array 272, the light spot also includes a horizontal stripe spot (first direction) and a vertical stripe spot (second direction). Then, as the MEMS micromirror tilts based on two axes, the distribution of the horizontal stripe spot will only change when the MEMS micromirror has a deflection amount about the slow axis during the deflection process, and the distribution of the vertical stripe spot will only change when the MEMS micromirror has a deflection amount about the fast axis during the deflection process. This helps to avoid the detection error caused by the dual-axis coupling of the MEMS micromirror, thereby increasing the accuracy of the MEMS micromirror tilt angle detection.

[0178] In addition, an embodiment of the present application also proposes an angle calculation method, which includes two parts: determining calibration parameters and calculating the angle based on the calibration parameters.

[0179] Figure 18 This is a flow chart of a method 1800 for determining calibration parameters proposed in an embodiment of the present application. When applied to a calibration turntable, before proceeding with the following steps, it is necessary to install any angle detection device proposed in the aforementioned embodiments of the present application on the calibration turntable and perform angle detection on the calibration turntable. Figure 8 The angle detection device shown is taken as an example for explanation, wherein the photodetector is a PD.

[0180] It should be understood that the calibration turntable's rotation mechanism is the same as that of the MEMS micromirror, namely, rotation via a first axis and a second axis. Of course, in practical applications, the calibration turntable can be directly replaced with a MEMS micromirror. The calibration parameters are determined using the following steps. For ease of description, the first axis is referred to as the x-axis, and the second axis is referred to as the y-axis.

[0181] S1810: Control the calibration turntable to rotate around the first rotation axis and the second rotation axis at a fixed step angle α°, and obtain the output signal of the angle detection device.

[0182] For ease of description, the output voltages of the 2×2 PDs corresponding to the 2×2 gratings (first grating array) on the upper right side of the grating cover are denoted as the output voltage U1 of the first quadrant, the output voltages of the 2×2 PDs corresponding to the 2×2 gratings (second grating array) on the upper left side of the grating cover are denoted as the output voltage U2 of the second quadrant, the output voltages of the 2×2 PDs corresponding to the 2×2 gratings (third grating array) on the lower left side of the grating cover are denoted as the output voltage U3 of the third quadrant, and the output voltages of the 2×2 PDs corresponding to the 2×2 gratings (fourth grating array) on the lower right side of the grating cover are denoted as the output voltage U4 of the fourth quadrant. The outputs of U1 to U4 are the sum or weighted average of the outputs of the PDs in their respective arrays.

[0183] Record the output voltages of the four quadrants at each step angle, with the number of steps being 2m+1, where m is a positive integer. The corresponding values of U1 to U4 at all step angles can then be represented by a (2m+1)×(2m+1) matrix. At each step angle, the calibration turntable rotates around the x-axis by [-mα, -(m-1)α, …, (m-1)α, mα], where α is the step angle. The same applies to the calibration turntable's rotation angle around the y-axis. As the input signals of each PD change with the angle of the two axes, their output signals also change accordingly.

[0184] S1820: Based on the difference and ratio algorithm, the output signals U1 to U4 are processed, and the processing results are amplified by a times, where a is an integer greater than 1.

[0185] Based on S1820, the input signal of the photodetector matrix related to the calibration turntable angle and the output signal (U1 to U4) of the photodetector matrix can present a monotonic correspondence relationship.

[0186] For example, the operation of S1820 can be completed by the following formula (1).

[0187]

[0188] S1830: The processing result of the above method a times is represented by a first parameter network, which includes a×a grids, each grid has a side length of 1, and each grid corresponds to a test point of the calibration turntable, wherein each grid carries a corresponding characteristic parameter, which is related to the rotation angle of the test point corresponding to the grid around the x-axis or y-axis.

[0189] S1840: Calculate the angle value corresponding to each grid based on the thin plate spline interpolation algorithm.

[0190] S1850: Calculate and save the linear difference parameter vector corresponding to each grid.

[0191] Taking the linear difference parameter of the ith grid as an example, the lower left corner point in the ith grid corresponds to the vector ai=[a i0 ,a i1 ,a i2 ,a i3 ] T and vector bi = [b i0 ,b i1 ,b i2 ,b i3 ] T .

[0192] It should be understood that based on the linear difference parameter vector corresponding to each grid, the two-axis rotation angle corresponding to each grid can be determined. The two-axis rotation angle corresponding to the lower left corner point of the i-th grid can be expressed by the following formula (2), where the i-th grid is any grid in the first parameter network.

[0193]

[0194] Among them, R xi is the difference and ratio of any point on the i-th grid about the x-axis, R yi is the difference and ratio of any point on the y-axis in the i-th grid, T xi is the angle of rotation about the x-axis corresponding to any point in the i-th grid, T yi is the rotation angle about the y-axis corresponding to any point in the i-th grid.

[0195] Based on the above formula (2), the parameter relationship between the i-th grid and the adjacent grid can be determined according to the distance d (d=1 in this example) between two adjacent grid center points or corresponding vertices (for example, the upper left corner point of the grid, the upper right corner point of the grid, the lower left corner point of the grid, or the lower right corner point of the grid) in the first parameter network. That is, the i-th grid corresponds to a in formula (2). i0 , a i1 , a i2 , b i0 , b i1 , b i2 By analogy, we can obtain the value of a in formula (2) corresponding to each grid in the first parameter network. i0 , a i1 , a i2 , b i0 , b i1 , b i2 The value of .

[0196] In some possible embodiments, the linear difference parameter vector corresponding to all the above grids is A={a1, a2, a3, ..., a n},B={b1,b2,b3,…,b n}, where n is the number of grids, can be stored in the processing chip of the angle detection device, or in a memory connected to the processing chip, or in a cloud server that communicates with the angle detection device in real time, so that it can be called up in a timely manner when the angle detection device measures the rotation angle of the MEMS micromirror. It should be understood that the linear difference parameter vector described above is the calibration parameter.

[0197] Correspondingly, the angle detection device can detect the target based on the calibration parameters obtained above by the following method.

[0198] Figure 19 It is a flowchart of a method 1900 for calculating angles based on calibration parameters proposed in an embodiment of the present application.

[0199] This method uses Figure 8 The angle detection device shown is described as an example.

[0200] and Figure 18 The corresponding description methods are consistent. In the following, the output voltage of the 2×2 PDs corresponding to the 2×2 gratings on the upper right of the grating cover plate is recorded as the output voltage U1 of the first quadrant, the output voltage of the 2×2 PDs corresponding to the 2×2 gratings on the upper left of the grating cover plate is recorded as the output voltage U2 of the second quadrant, the output voltage of the 2×2 PDs corresponding to the 2×2 gratings on the lower left of the grating cover plate is recorded as the output voltage U3 of the third quadrant, and the output voltage of the 2×2 PDs corresponding to the 2×2 gratings on the lower right of the grating cover plate is recorded as the output voltage U4 of the fourth quadrant.

[0201] S1910: Obtain the output voltages U1 to U4 of the photodetector matrix.

[0202] S1920: Determine the difference and ratio of the output voltages U1 to U4, and determine a first parameter network.

[0203] The difference and ratio of U1 to U4 can be determined by the above formula (1).

[0204] In some possible embodiments, when the difference and the ratio are not integers, the difference and the ratio may be rounded down.

[0205] S1930: Determine the linear difference parameter corresponding to each grid in the first parameter network.

[0206] In some possible embodiments, the difference and ratio corresponding to the lower left corner point of the i-th grid are recorded as: (R xi ,R yi ), then the difference and ratio corresponding to the upper left corner point of the i-th grid is recorded as: (R xi ,Ry(i+1) ), the difference and ratio corresponding to the lower right corner point of the i-th grid are recorded as: (R x(i+1) ,R yi ), the difference and ratio corresponding to the upper right corner point of the i-th grid are recorded as: (R x(i+1) ,R y(i+1) Based on the differences and ratios corresponding to these four corner points, the linear difference parameter vector corresponding to the i-th grid can be obtained. Similarly, the linear difference parameters corresponding to each grid can be determined.

[0207] S1940: Substitute the linear difference parameter corresponding to each grid into the first formula to determine the rotation angle T corresponding to each grid x and T y .

[0208] Among them, the first formula is the above formula (2).

[0209] S1950: According to the rotation angle T corresponding to each grid xi and T yi , determine the rotation angle of the MEMS mirror.

[0210] In some possible embodiments, the method 1900 may be executed by a microcontroller unit (MCU).

[0211] Based on the above technical solution, a mathematical formula for angle calculation can be determined through experimentation. This mathematical formula can then be directly applied to the angle detection device 300, allowing the device 300 to directly determine the MEMS micromirror's rotation angle based on the output of the photodetector matrix. Furthermore, because this method is based on the unique dual-axis decoupling detection structure of the angle detection device 300, it not only eliminates errors caused by temperature drift in the angle detection device but also helps reduce angle detection errors introduced by dual-axis coupling.

[0212] Figure 20 This is a schematic diagram of an integrated angle detection device proposed in an embodiment of the present application.

[0213] refer to Figure 20 As shown, the above-mentioned device 200 or device 300 can manufacture the photodetector matrix 212 and the light source 211 on the same silicon wafer through processes such as epitaxy and doping.

[0214] It should be understood that the above-mentioned device 200 or device 300 can be manufactured using semiconductor manufacturing technology, so there is no need to directly mount the photodetector on the silicon substrate. In the process of directly mounting the photodetector on the silicon substrate, large mounting errors are likely to occur. Manufacturing photodetectors on silicon wafers based on semiconductor manufacturing technology can effectively reduce position errors between photodetectors due to the high precision of this technology.

[0215] Based on the above technical solution, the light source 211 and the photodetector matrix are integrated on a silicon wafer, that is, the silicon wafer is equivalent to the aforementioned silicon substrate 214, so as to realize the detection of the tilt angle of the MEMS micromirror, without the need for additional packaging steps, thereby effectively reducing the packaging cost of the angle detection device 20. In addition, based on the photodetector matrix obtained by integrated production, the photodetectors therein also have consistency in their response capabilities to light, which helps to avoid errors introduced by differences in the response capabilities of the photodetectors.

[0216] It should be noted that the deployment position of the above-mentioned device 300 is similar to the deployment position of the above-mentioned device 200. The specific extended description is detailed in the above-mentioned corresponding embodiment, which will not be repeated here.

[0217] Based on the angle detection device 200 and the device 300 proposed in the aforementioned embodiments, the embodiments of the present application also propose a laser radar scanning system.

[0218] Figure 21 It is a schematic diagram of a laser radar scanning system 2100 proposed in an embodiment of the present application.

[0219] The system 2100 includes:

[0220] The MEMS micromirror device 10 comprises a MEMS micromirror 108, a first rotation axis and a second rotation axis, wherein the MEMS micromirror 108 is tilted based on the first rotation axis and the second rotation axis;

[0221] The angle detection device 20 is arranged below the MEMS micromirror device 10 and opposite to the first surface of the MEMS micromirror 108. The angle detection device 20 includes: a light source 211 and a photodetector matrix 212, wherein the photodetector matrix 212 includes N photodetector arrays 2121. The photodetector matrix 212 and the light source 211 are located in the same plane, N is greater than or equal to 4, and the light source 211 is located at the center of the photodetector matrix 212.

[0222] In some possible embodiments, the photodetector array 2121 includes four photodetectors distributed in a 2×2 pattern, and the N photodetector arrays 2121 are respectively located around the light source 211 .

[0223] In some possible embodiments, the light source 211 is configured to emit a light beam toward a first surface of the MEMS micromirror 108 . The first surface of the MEMS micromirror is coated with a reflective layer. The MEMS micromirror is configured to reflect the light beam toward a photodetector matrix.

[0224] In some possible embodiments, the light source 211 and the photodetector matrix 212 are located on the same silicon substrate 214 .

[0225] In some possible embodiments, the angle detection device 20 further includes a grating cover plate 270, which includes N grating arrays 272. The grating cover plate 270 is disposed above the photodetector matrix 212. The positions of the N grating arrays 272 correspond one-to-one to the positions of the N photodetector arrays 2121. The stripe direction of the first portion of the gratings in the N grating arrays 272 is a first direction, and the stripe direction of the second portion of the gratings in the N grating arrays 272 is a second direction. The first direction is parallel to the first rotation axis of the MEMS micromirror, and the second direction is parallel to the second rotation axis of the MEMS micromirror.

[0226] In some possible embodiments, the grating cover plate 270 further includes a lens 271 , the position of which corresponds to the position of the light source 211 . The lens 271 is configured to ensure that the light spot distribution formed by the light beam emitted by the light source 211 corresponds to the stripe direction and stripe shape of the N grating arrays 272 in the grating cover plate 270 .

[0227] In some possible embodiments, a first spacing exists between the first grating in the first portion of the grating and a second grating adjacent to the first grating in the second direction, and stripes of the first grating and stripes of a third grating adjacent to the first grating in the first direction are staggered by a second spacing in the second direction; a first spacing exists between the fourth grating in the second portion of the grating and a fifth grating adjacent to the fourth grating in the first direction, and stripes of the fourth grating and stripes of a sixth grating adjacent to the fourth grating in the second direction are staggered by a second spacing in the first direction, the first spacing is (n+(1 / 4))d, or (n+(1 / 2))d, and the second spacing is m×d, where n and m are integers, and d is the stripe width of the grating.

[0228] In some possible embodiments, a light shielding portion is provided on a side surface of the lens 271 , and the light shielding portion is used to shield interference light incident from the side surface of the lens 271 .

[0229] In some possible embodiments, the light source is a VCSEL or an LED, and the photodetector is a PD.

[0230] It should be understood that the angle detection device 20 described above is consistent with the device 200 or device 300 of the aforementioned embodiment. Therefore, for details regarding angle measurement by the angle detection device 20, please refer to the corresponding descriptions for the aforementioned devices 200 or 300, and will not be repeated here. Similarly, the structural schematic diagram of the angle detection device 20 is also detailed in the corresponding structural schematic diagram of the aforementioned devices 200 or 300.

[0231] For example, the first rotation axis may be a fast axis of the MEMS micromirror, and the second rotation axis may be a slow axis of the MEMS micromirror.

[0232] Figure 22 Schematic diagram of a MEMS micromirror device 10 proposed in an embodiment of the present application.

[0233] refer to Figure 22 As shown in (a), Figure 22 (a) shows the front structure of the MEMS micromirror device 10 , which further includes: a substrate 101 , a driving coil 103 , a first rotation axis support beam 102 , a second rotation axis support beam 104 and a pad 105 .

[0234] The MEMS micromirror 108 is connected to the driving coil 103 via a first rotating shaft;

[0235] The driving coil 103 includes a coil frame and a coil manufactured based on MEMS manufacturing process standards; the coil frame is connected to the substrate 101 via a second rotating shaft, and the first rotating shaft and the second rotating shaft are perpendicular to each other, so that the MEMS micromirror 108 can deflect in the horizontal and vertical directions.

[0236] The pad 105 is used to electrically connect the MEMS micromirror 108 to an external circuit.

[0237] In some possible embodiments, the driving coil 103 may be a planar or stacked coil prepared by deposition, electroplating, or the like.

[0238] refer to Figure 22 As shown in (b), Figure 22 (b) shows the back structure of the MEMS micromirror device 10

[0239] In some possible embodiments, a first surface of the MEMS micromirror 108 is coated with a reflective film, and the first surface is opposite to the angle detection device 20. It should be understood that the first surface may be the bottom surface (or back surface) of the MEMS micromirror 108 described in the above embodiment.

[0240] In some possible embodiments, the above-mentioned MEMS micromirror device 10 further includes a first support frame 106 and a second support frame 107, wherein the first support frame 106 is arranged on the bottom surface (or back) of the MEMS micromirror 108, and the second support frame 107 is arranged on the bottom surface (or back) of the coil frame of the driving coil 103, so as to avoid large deformation of the MEMS micromirror 108 and the coil frame of the driving coil 103 during the manufacturing process or the operation process.

[0241] Based on the above technical solution, the laser radar scanning system can accurately measure the tilt angle of the MEMS micromirror, which can not only eliminate the error caused by temperature drift of the device, but also avoid the detection error caused by the dual-axis coupling of the MEMS micromirror, and realize the accurate detection of the tilt angle of the MEMS micromirror by the laser radar scanning system, thereby ensuring the accuracy of real-time control of the MEMS micromirror rotation angle.

[0242] In some possible embodiments, the system 2100 further includes:

[0243] A driving device 30 is provided below the angle detection device 20 , and is used to drive the MEMS micromirror 108 to tilt based on the first rotation axis and the second rotation axis;

[0244] The supporting device 40 is used to support the MEMS micromirror device 10 , the angle detecting device 20 and the driving device 30 .

[0245] Figure 23 Schematic diagram of the structure of a driving device 30 proposed in an embodiment of the present application.

[0246] refer to Figure 20 As shown, the driving device 30 includes a plurality of permanent magnets and a bottom plate 305, wherein the plurality of permanent magnets are fixed on the bottom plate 305. For example, the driving device 30 may include four permanent magnets (301, 302, 303, 304), and the bottom plate 305 may be an iron sheet.

[0247] In addition, an embodiment of the present application also proposes a vehicle, which includes any one of the laser radar scanning systems proposed in the aforementioned embodiments, or the laser radar scanning system of the vehicle includes any one of the angle detection devices proposed in the aforementioned embodiments.

[0248] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0249] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0250] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0251] The units described as separate components may or may not be physically separate, and 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 these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0252] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0253] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application.

[0254] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An angle detection device for detecting the tilt angle of a micro-electromechanical system (MEMS) micromirror based on a first rotation axis and a second rotation axis, characterized in that: The device comprises: light source; A photodetector matrix includes N photodetector arrays, the photodetector matrix and the light source are located in the same plane, N is greater than or equal to 4, and the light source is located at the center of the photodetector matrix.

2. The device according to claim 1, characterized in that The photodetector array includes four photodetectors distributed in a 2×2 pattern, and the N photodetector arrays are respectively located around the light source.

3. The device according to claim 1 or 2, characterized in that The light source is used to emit a light beam to the first surface of the MEMS micromirror. The first surface of the MEMS micromirror is coated with a reflective layer. The MEMS micromirror is used to reflect the light beam to the photodetector matrix.

4. The device according to any one of claims 1 to 3, characterized in that The light source and the photodetector matrix are located on the same silicon substrate.

5. The device according to any one of claims 1 to 4, characterized in that The device also includes a grating cover plate, which includes N grating arrays. The grating cover plate is arranged on the photodetector matrix. The positions of the N grating arrays correspond one-to-one to the positions of the N photodetector arrays. The stripe direction of the first part of the gratings in the N grating arrays is a first direction, and the stripe direction of the second part of the gratings in the N grating arrays is a second direction. The first direction is parallel to the first rotation axis of the MEMS micromirror, and the second direction is parallel to the second rotation axis of the MEMS micromirror.

6. The device according to claim 5, characterized in that The grating cover plate further includes a lens, the position of the lens corresponds to the position of the light source, and the lens is used to make the spot distribution formed by the light beam emitted by the light source correspond to the stripe direction and stripe shape of the N grating arrays in the grating cover plate.

7. The device according to claim 5 or 6, characterized in that A first spacing exists between a first grating in the first partial grating and a second grating adjacent to the first grating in the second direction, and stripes of the first grating and stripes of a third grating adjacent to the first grating in the first direction are staggered by a second spacing in the second direction; a fourth grating in the second partial grating and a fifth grating adjacent to the fourth grating in the first direction have the first spacing, and stripes of the fourth grating and stripes of a sixth grating adjacent to the fourth grating in the second direction are staggered by the second spacing in the first direction, the first spacing is (n+(1 / 4))d, or (n+(1 / 2))d, and the second spacing is m×d, where n and m are integers, and d is the stripe width of the grating.

8. The device according to claim 6 or 7, characterized in that A light shielding portion is provided on the side surface of the lens, and the light shielding portion is used to shield the interfering light incident from the side surface of the lens.

9. The device according to any one of claims 1 to 8, characterized in that The photodetector matrix is used to collect the light beam reflected by the MEMS micromirror and output N collection results. There is a mapping relationship between the N collection results and the tilt angle of the MEMS micromirror.

10. The device according to any one of claims 1 to 9, characterized in that The light source is a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED), and the photodetector is a photodiode (PD).

11. A laser radar scanning system, characterized in that: include: A micro-electromechanical system (MEMS) micro-mirror device comprises a MEMS micro-mirror, a first rotation axis and a second rotation axis, wherein the MEMS micro-mirror is tilted based on the first rotation axis and the second rotation axis; The angle detection device according to any one of claims 1 to 10, wherein the angle detection device is arranged below the MEMS micromirror device and opposite to the first surface of the MEMS micromirror.

12. The system according to claim 11, wherein: The system further comprises: a driving device, disposed below the angle detection device, for driving the MEMS micromirror to tilt based on the first rotation axis and the second rotation axis; A supporting device is used to support the MEMS micromirror device, the angle detection device and the driving device.

13. A vehicle, characterized in that: It includes a laser radar scanning system as described in claim 11 or 12, or the laser radar scanning system of the vehicle is equipped with an angle detection device as described in any one of claims 1 to 10.

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