Detection device, detection method and laser radar

Abstract

The present invention discloses a detection device, comprising: a receiving lens for receiving and converging echoes; a detection unit for receiving echoes and outputting electrical signals, comprising at least one macropixel, each macropixel comprising an array consisting of a plurality of detectors; an aperture array, arranged between the receiving lens and the detection unit and located on or near a focal plane, the aperture array comprising at least one sub-aperture, each sub-aperture comprising a plurality of independently controllable optical switch pixels, each sub-aperture enabling one or more of the optical switch pixels to be turned on to form a light-transmitting area, thereby allowing the echo to pass through and illuminate a corresponding macropixel; a processing unit for performing calculations and processing based on the electrical signals, a control unit coupled to the aperture array and the processing unit, for controlling each sub-aperture in the aperture array, and for at least one of the sub-apertures, controlling the opening and closing of the optical switch pixels of the sub-aperture based on the light spot distribution of the echo on the macropixel corresponding to the sub-aperture.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronic technology, and in particular to a detection device, a detection method and a laser radar. Background Art

[0002] Currently, LiDAR technology is widely used in areas such as autonomous driving, surveying and mapping, and unmanned warehouses. Due to their high sensitivity, single-photon detectors have gradually matured in recent years and are being used in LiDAR. Single-photon detector devices, SPADs, are light detection arrays composed of multiple SPAD (single-photon avalanche diode) units. Unlike SiPM / MPPC (silicon photomultiplier tubes, whose basic component is also SPAD, but they are constructed differently from SPADs and lack independent unit location and readout), the output of each SPAD unit in a SPADs device is digital and can be directly calculated on the backend without the need for analog-to-digital conversion through an ADC or TDC. Furthermore, each SPAD unit has a location-selective readout feature, a feature not found in SiPM / MPPCs.

[0003] Currently, as a technical approach, the application of SPADs devices in LiDAR has been adopted by more and more manufacturers. For example, a LiDAR composed of SPADs and VCSELs has been used to achieve three-dimensional perception capabilities. The autonomous driving field requires LiDAR with medium- and long-range measurement capabilities. Unlike the single-light source operation mode of FLASH radar, LiDAR with medium- and long-range measurement capabilities often requires a laser emitting array and a corresponding photodetection array. Each laser and its corresponding one or more photodetection units are called a detection channel, namely a transmitting channel and a receiving channel.

[0004] Since a SPAD unit can only provide two outputs: Geiger occurred and Geiger not occurred, using multiple SPAD units to form a SPADs as a single-channel receiving unit can effectively improve the dynamic response range of the channel, such as Figure 1 The single-channel SPADs shown in the figure have an array detection unit that includes multiple (multi-channel) SPADs. As a single-photon device, a single photon can trigger a Geiger avalanche. Therefore, under strong ambient light conditions, the lidar needs to consider suppressing the influence of ambient light from the perspective of the optical system. Placing filters in the optical receiving lens group or on the surface of the SPADs is a common method of suppressing ambient light. In order to further suppress the ambient light in the field of view and the stray light of the receiving optical system, a mechanical aperture is often considered in the optical system. The mechanical aperture is an array of small holes corresponding to the detection channel, and its aperture range is generally from a few millimeters to tens of microns. Another solution is to only read part of the SPAD unit output of the channel SPADs to achieve an effect similar to that of an aperture.

[0005] The existing technology has the following disadvantages: Although the introduction of mechanical aperture can effectively suppress ambient light, Figure 2 As shown (the two beams of light in the figure represent different incident angles), but there are the following defects.

[0006] In a rangefinder optical system, the position and size of the radar's receiving spot in the focal plane are related to the distance of the object being measured. A sufficiently large aperture ensures that laser echoes reflected at different distances can be received by the SPADs. However, a larger aperture increases the field of view of the laser receiving channel and reduces the ability to suppress stray light within the receiving lens, resulting in a lower radar system's immunity to ambient light interference. Because the mechanical aperture is placed near the focal plane of the receiving optical system, optical path deviations caused by mechanical deformation of the transmitting and receiving optical systems can cause the position of the receiving spot to shift in the focal plane. This can block some of the laser echoes and prevent them from being detected by the SPADs. During production, the mechanical aperture must be adjusted to the appropriate position and angle, increasing the accuracy and difficulty of optical alignment during production. The mechanical aperture cannot dynamically adjust its aperture size, thus failing to simultaneously achieve the desired goals of suppressing ambient light, reducing the receiving field of view, and improving long-range measurement performance, while also reducing production complexity and enhancing robustness to mechanical deformation.

[0007] Another method uses only part of the SPAD unit output of the channel SPADs. When the light spot is small, the dynamic response range of the channel SPADs will be reduced due to the limited number of activated SPAD units.

[0008] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the existing technologies in this field. Summary of the Invention

[0009] To solve the above technical problems, an embodiment of the present invention provides a detection device, comprising:

[0010] a receiving lens configured to receive and focus an echo of the detection laser beam reflected on a target object;

[0011] a detection unit configured to receive the echo and output an electrical signal, the detection unit comprising at least one macro pixel, each macro pixel comprising an array consisting of a plurality of detectors;

[0012] an aperture array, disposed between the receiving lens and the detection unit and located on or near the focal plane of the receiving lens, the aperture array comprising at least one sub-aperture, each sub-aperture comprising a plurality of independently controllable optical switch pixels, each sub-aperture being configured such that one or more of the optical switch pixels are turned on to form a light-transmitting area, thereby allowing an echo from the receiving lens to pass through and illuminate a corresponding macropixel of the detection unit;

[0013] a processing unit configured to perform calculations and processing based on the electrical signal,

[0014] A control unit is coupled to the aperture array and the processing unit and is configured to control each sub-aperture in the aperture array, and for at least one of the sub-apertures, control the opening and closing of the optical switch pixel of the sub-aperture according to the spot distribution of the echo on the macro pixel corresponding to the sub-aperture.

[0015] According to one aspect of the present invention, for the at least one sub-aperture, the control unit is configured to control the light switching pixels of the sub-aperture based on the spot distribution of the echo on the macro-pixel corresponding to the sub-aperture, so that the spot distribution of the echo on the sub-aperture is basically consistent with the light-transmitting area of ​​the sub-aperture.

[0016] According to one aspect of the present invention, for the at least one sub-aperture, the processing unit is configured to determine the spot distribution of the echo on the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture, and the multiple detectors included in each macropixel are independently addressable.

[0017] According to one aspect of the present invention, for the at least one sub-aperture, the processing unit determines the Geiger avalanche number distribution of the detector in a preset area of ​​the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture, and determines the spot distribution of the echo on the macropixel based on the Geiger avalanche number distribution.

[0018] According to one aspect of the present invention, the preset area is determined by the light-transmitting area of ​​the sub-aperture corresponding to the macro pixel, the focal length f of the receiving lens, and the distance d between the detection unit and the aperture array.

[0019] According to one aspect of the present invention, for the at least one sub-aperture, the control unit is configured to control the optical switching pixels of the sub-aperture so that the Geiger avalanche number distribution of the detector in the preset area of ​​the macro pixel corresponding to the sub-aperture is basically consistent with the standard distribution.

[0020] According to one aspect of the present invention, for the at least one sub-aperture, the control unit is configured to control the optical switching pixels of the sub-aperture according to the deviation between the Geiger avalanche number distribution of the detector in the preset area of ​​the macro-pixel corresponding to the sub-aperture and the standard distribution.

[0021] According to one aspect of the present invention, the detector comprises a single-photon detector, and the aperture array comprises a liquid crystal aperture or an electrically controlled filter.

[0022] According to one aspect of the present invention, the aperture array may be configured as an attenuation plate with adjustable transmittance, and the control unit is configured to initialize the aperture array according to a configuration file.

[0023] According to one aspect of the present invention, the control unit is configured to: when the configuration file is missing, configure the aperture array as an attenuation plate, and update the configuration file according to the size, position and shape of the light spot of the echo on the detection unit, and the correspondence between the light spot and the aperture array.

[0024] The present invention also provides a detection method, comprising:

[0025] S401: Converging the detection laser beam through a receiving lens to detect the echo reflected by the target object;

[0026] S402: Providing a light-clearance area by using an aperture array, wherein the aperture array is located on or near the focal plane of the receiving lens, the aperture array includes at least one sub-aperture, each sub-aperture includes a plurality of independently controllable optical switch pixels, and each sub-aperture is configured such that one or more of the optical switch pixels are turned on to form the light-clearance area, thereby allowing the echo from the receiving lens to pass through;

[0027] S403: Receiving an echo passing through the light-transmitting area by a detection unit, wherein the detection unit includes at least one macropixel, each macropixel including an array consisting of a plurality of detectors, and the echo passing through the light-transmitting area of ​​a sub-aperture is irradiated onto a corresponding macropixel of the detection unit and converted into an electrical signal;

[0028] S404: Controlling the opening and closing of the optical switch pixel of at least one sub-aperture in the aperture array according to the light spot distribution on the macro pixel corresponding to the sub-aperture.

[0029] According to one aspect of the present invention, step S404 includes: for the at least one sub-aperture, based on the spot distribution of the echo on the macropixel corresponding to the sub-aperture, controlling the light switch pixels of the sub-aperture, so that the spot distribution of the echo on the sub-aperture is substantially consistent with the light transmission area of ​​the sub-aperture.

[0030] According to one aspect of the present invention, step S404 includes: for the at least one sub-aperture, determining the spot distribution of the echo on the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture, wherein the multiple detectors included in each macropixel are independently addressable.

[0031] According to one aspect of the present invention, step S404 further includes: for the at least one sub-aperture, determining the Geiger avalanche number distribution of the detector in a preset area of ​​the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture, and determining the spot distribution of the echo on the macropixel based on the Geiger avalanche number distribution.

[0032] According to one aspect of the present invention, the preset area is determined by the light-transmitting area of ​​the sub-aperture corresponding to the macro pixel, the focal length f of the receiving lens, and the distance d between the detection unit and the aperture array.

[0033] According to one aspect of the present invention, step S404 includes: for the at least one sub-aperture, controlling the optical switch pixels of the sub-aperture so that the Geiger avalanche number distribution of the detector in the preset area of ​​the macro pixel corresponding to the sub-aperture is substantially consistent with the standard distribution.

[0034] According to one aspect of the present invention, step S404 includes: for the at least one sub-aperture, controlling the optical switch pixel of the sub-aperture according to the deviation between the Geiger avalanche number distribution of the detector in the preset area of ​​the macro pixel corresponding to the sub-aperture and the standard distribution.

[0035] According to one aspect of the present invention, the detection method further includes:

[0036] Initialize the aperture array.

[0037] According to one aspect of the present invention, the step of initializing the aperture array includes: initializing the aperture array according to a configuration file; when the configuration file is missing, configuring the aperture array as an attenuation plate with adjustable transmittance, updating the configuration file according to the size, position and shape of the light spot of the echo on the detection unit, and the correspondence between the light spot and the aperture array, and then initializing the aperture array according to the configuration file.

[0038] The present invention also provides a laser radar, comprising:

[0039] a transmitting unit, comprising at least one laser, configured to emit a detection laser beam for detecting a target object;

[0040] A receiving unit, wherein the receiving unit includes the detection device as described above, and the detection device is configured to receive the echo after the detection laser beam is reflected on the target object and process the echo signal.

[0041] According to one aspect of the present invention, a laser of the transmitting unit, a macro pixel of the receiving unit and a sub-aperture corresponding to the macro pixel constitute a detection channel.

[0042] According to one aspect of the present invention, the laser comprises a vertical cavity surface emitting laser.

[0043] The embodiments of the present invention address the issue of spot shift at different distances under paraxial optical path conditions, address the received spot shift caused by mechanical deformation, and resolve alignment issues during production. Furthermore, the preferred embodiments of the present invention do not change the number of SPAD units read within each channel, thus maintaining the dynamic response of the SPADs within the channel. Furthermore, the present invention addresses the saturation issue of SPADs devices under strong light. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0045] Figure 1 A schematic diagram showing the use of multiple SPAD units to form a SPADs as a single-channel receiving unit;

[0046] Figure 2 A schematic diagram showing the use of a mechanical aperture to suppress ambient light;

[0047] Figure 3 A detection device according to an embodiment of the present invention is shown;

[0048] Figure 4 A schematic diagram showing the spot size and sub-aperture formed by echoes from the same direction on the aperture array when the target is at different distances;

[0049] Figure 5 The corresponding relationship between the light-transmitting area formed by the aperture array and the detector array illuminated by the light-transmitting area is shown;

[0050] Figure 6A 、 6B 6C show different types of light spots on the aperture array;

[0051] Figure 7A and 7B The figure shows the superposition effect of 100 exposures for a 50*50 detector array;

[0052] Figure 8 The figure shows the distribution of the number of detector excitations within the preset area of ​​the corresponding macro pixel when the light transmission area of ​​the sub-aperture matches the focal plane spot;

[0053] Figure 9 The figure shows the distribution of the number of detector excitations within the preset area of ​​the corresponding macro pixel when the light transmission area of ​​the sub-aperture is larger than the size of the focal plane spot;

[0054] Figure 10 The figure shows the distribution of the number of detector excitations within the preset area of ​​the corresponding macro pixel when the position of the light-transmitting area of ​​the sub-aperture and the focal plane spot are offset;

[0055] Figure 11 The figure shows the distribution of the number of detector excitations within the preset area of ​​the corresponding macro pixel when the light transmission area of ​​the sub-aperture is smaller than the focal plane spot;

[0056] Figure 12 A schematic diagram showing initialization of a sub-aperture when a configuration file is missing or erroneous;

[0057] Figure 13 A flowchart showing sub-aperture initialization and adjustment of the light transmission area of ​​the sub-aperture is shown;

[0058] Figure 14 A schematic diagram showing a laser radar according to an embodiment of the present invention; and

[0059] Figure 15 A detection method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0060] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0061] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for the purpose of facilitating the description of the present invention and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the aforementioned features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0062] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, removable, or integral connections; mechanical, electrical, or intercommunication connections; direct or indirect connections through an intermediary; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0063] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may also include the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a lower level than the second feature.

[0064] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0065] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0066] Figure 3 FIG. 1 shows a detection device 10 according to an embodiment of the present invention, which will be described in detail below with reference to the accompanying drawings. Figure 3As shown, the detection device 10 includes a receiving lens 11, a detection unit 12, an aperture array 13, a processing unit 14 and a control unit 15, and preferably includes a filter 16. The receiving lens 11 is configured to receive and converge the echo of the detection laser beam reflected on the target object. The receiving lens 11 can generally include a single lens or a lens group for converging the echo onto its focal plane. The aperture array 13 is arranged on or near the focal plane of the receiving lens 11, so that when the echo is parallel light, it can be converged to a point or a small area on the aperture array 13 through the converging effect of the receiving lens 11. The aperture array 13 includes a plurality of optical switch pixels 131 (i.e., pixels 131 and 131) that can be independently controlled to open and close. Figure 3 Each small square of the middle aperture array 13), such as Figure 4 As shown clearly. Each light switch pixel 131 has an "on", "off" and "half-on" state, and can be freely switched between multiple states, for example, under the control of the control unit 15 described below. When a light switch pixel 131 is switched to the "on" state, the light switch pixel 131 will allow the light beam incident thereon to pass through; when a light switch pixel 131 is switched to the "off" state, the light switch pixel 131 will not allow the light beam incident thereon to pass through. As shown Figure 3 As shown in FIG, the light-switch pixel 131 marked with shadows is in the "off" state, and the two light-switch pixels 131 marked with blank squares are in the "on" state. According to one embodiment of the present invention, the aperture array includes a liquid crystal aperture or an electrically controlled filter.

[0067] The detection unit 12 is arranged on the side of the aperture array 13 opposite to the receiving lens 11, that is, the aperture array 13 is located between the receiving lens 11 and the detection unit 12. The detection unit 12 is configured to receive the echo passing through the aperture array 13 and output an electrical signal. Figure 1 The aperture array 13 in the aperture array 13 implements an "optical gate." By controlling the opening and closing of each optical switch pixel 131 in the aperture array 13, the echo can pass through as fully as possible and be incident on the detection unit 12, while effectively isolating ambient light or background noise from entering the detection unit 12. The detection unit 12 can, for example, be an array composed of multiple detectors 121. The detectors 121 are preferably single-photon avalanche diodes (SPADs). Each detector 121 can independently respond to incident photons and output an electrical signal.

[0068] It is easy for those skilled in the art to understand that the array of detectors 121 in the detection unit 12 and the aperture array composed of the optical switch pixels 131 can be a one-dimensional array or a two-dimensional array, which are all within the protection scope of the present invention.

[0069] The processing unit 14 is electrically connected or in communication with the detection unit 12, thereby acquiring the electrical signal output by the detection unit 12 and performing corresponding calculations and processing based on the electrical signal. For example, when used in a laser radar, the processing unit 14 can calculate the distance and / or reflectivity of a target object based on the electrical signal.

[0070] In the present invention, the detection unit 12 includes at least one macro pixel, preferably includes a plurality of macro pixels, each macro pixel includes an array composed of a plurality of detectors 121, for example Figure 1 Each SPAD in the array is a macropixel, which is an array composed of multiple SPAD units. Correspondingly, the aperture array 13 includes at least one sub-aperture, preferably multiple sub-apertures. Each sub-aperture includes multiple independently controllable optical switch pixels. Each optical switch pixel is, for example, a liquid crystal cell, its state controlled by applying an electric field. Each sub-aperture is configured so that one or more of the optical switch pixels are turned on to form a light-transmitting area, allowing the echo from the receiving lens to pass through and illuminate a corresponding macropixel of the detection unit. Therefore, one sub-aperture corresponds to one macropixel, forming a receiving channel.

[0071] Each receiving channel corresponds to an echo incident on the receiving lens 11 along a certain direction. Still using the LiDAR application as an example, each macropixel must ensure that, regardless of the distance between the target and the LiDAR, as long as the echo's direction corresponds to that receiving channel, the light spot formed by the echo on the detection unit 12 after convergence by the receiving lens 11 will fall completely within the range of the macropixel of that receiving channel.

[0072] Figure 4 The diagram shows the spot size and sub-aperture formed by the echo in the same direction on the aperture array 13 when the target is at different distances. Figure 4 The left side of the diagram shows that when the target is far away, for example, about 100 meters away, the spot area formed on the aperture array 13 is small. However, when the target is close at the same orientation (angle), for example, about 10 meters away, the spot area formed on the aperture array 13 is larger. Therefore, when setting the size of the sub-aperture, the sub-aperture can be set relatively large to ensure that the echo returning along the angle or direction will fall within the range of the corresponding sub-aperture after passing through the receiving lens 11. Figure 4In the figure, the sub-aperture 132 is schematically shown in a box, from which it can be seen that both the far-field light spot and the near-field light spot fall within the range of the sub-aperture. When used in a laser radar, since each laser radar has its theoretical detection range, for example, 5-200 meters, and generally the closer the target is, the larger the light spot is. At this time, the light spot size when the target is 5 meters away from the laser radar can be used as the size of the sub-aperture, or it can be appropriately increased on this basis, for example, by 5% or 10%. In addition, the present invention is not limited to the shape of the sub-aperture, and the sub-aperture can be as follows: Figure 4 The shape shown is square, but it can also be a substantially circular shape or other polygonal shape, all of which are within the scope of protection of the present invention. Those skilled in the art will readily understand that when the aperture array 13 includes multiple sub-apertures 132, each sub-aperture unit 132 can be isolated from each other or partially overlap with each other.

[0073] Each sub-aperture 132 of the aperture array 13 forms a one-to-one correspondence with a macropixel. When the optical switch pixel of each sub-aperture is turned on, it allows the echo from the receiving lens to pass through and illuminate a corresponding macropixel of the detection unit. The following describes how to determine the macropixel corresponding to each sub-aperture.

[0074] After the optical path of the detection unit 10 is determined, the laser echo will be imaged on the focal plane of the receiving lens (on the aperture array). When the focal spot matches the light-transmitting area of ​​the aperture array, this can ensure that all echoes pass through and are detected while reducing ambient light interference. At this time, the proportional relationship between the light-transmitting area of ​​the aperture array 13 and the illuminated area on the detection unit 12 is determined. Figure 5 As shown, taking a single receiving channel as an example, the corresponding relationship between the size L1 of the light-transmitting area formed by the sub-aperture in the aperture array and the size L2 of the detector array in the macro pixel illuminated by it is as follows: Figure 5 As shown, the focal plane is at a distance f from the receiving lens 11, and the detector array is positioned at a distance d from the focal plane. The photosensitive area L2 on the detector array within a macropixel is related to the focal plane spot size (i.e., the size of the light-transmitting area L1 of the sub-aperture), the focal length f, and the distance d to the receiving lens aperture. Therefore, the position and size of the macropixel corresponding to each sub-aperture can be determined. Figure 5 The relationship between the size L1 of the light-transmitting area of ​​a sub-aperture and the size L2 of the detector array in the macropixel illuminated by it is described in one dimension. The same applies to the relationship between the two in other dimensions and will not be repeated here. The above description uses the sub-aperture of a single receiving channel and its corresponding macropixel as an example. The situation with multiple receiving channels is similar and will not be repeated here.

[0075] Figure 3The control unit 15 is coupled to the aperture array 13 and the processing unit 14, and is configured to control each sub-aperture in the aperture array 13, and for at least one of the sub-apertures, control the opening and closing of the optical switch pixel of the sub-aperture according to the spot distribution of the echo on the macro pixel corresponding to the sub-aperture.

[0076] As described above, during actual LiDAR detection, the size and position of the echo focal plane spot change with the position of the target. This means that the focal plane spot may not match the preset light transmission area of ​​the sub-aperture. In this case, either part of the echo is blocked by the sub-aperture and cannot be detected by the macropixel, or the sub-aperture is too large relative to the focal plane spot size, introducing significant ambient light interference. Therefore, according to one embodiment of the present invention, for the at least one sub-aperture, the control unit 15 is configured to control the optical switching pixels of the sub-aperture based on the spot distribution of the echo on the macropixel corresponding to the sub-aperture, so that the spot distribution of the echo on the sub-aperture is substantially consistent with the light transmission area of ​​the sub-aperture. Specifically, the optical switching pixels on the sub-aperture that are illuminated by the echo are turned on, allowing the echo to pass through, while the optical switching pixels on the sub-aperture that are not illuminated by the echo are turned off, blocking ambient light.

[0077] Figure 6A 、 6B Figures 6 and 6C show different types of light spots on the aperture array. On the aperture array 13, shaded light switch pixels indicate they are not illuminated by the echo and are therefore in the off state. Unshaded light switch pixels indicate they are illuminated by the echo and are controlled to be in the on state, forming a light-transmitting area.

[0078] Figure 6A The far-field spot is shown. The spot on aperture array 13 is roughly circular, with a diameter approximately equal to the width of four optical switch pixels. In this case, by controlling the activation of some of the optical switch pixels in the sub-aperture of the detection channel, the echo spot distribution on the sub-aperture is essentially consistent with (i.e., matches) the light transmission area of ​​the sub-aperture. Figure 6B The figure shows the near-field spot, where the spot on the aperture array 13 is roughly circular, with a diameter of about 6 optical switch pixels. In this case, the light transmission area of ​​the sub-aperture can be opened wider while maintaining the circular shape. Figure 6C The case of an irregular light spot is shown. In this case, some optical switch pixels of the sub-aperture of the detection channel can also be controlled to be turned on, so that the light spot distribution of the echo on the sub-aperture is basically consistent with the light-transmitting area of ​​the sub-aperture.

[0079] The concepts of sub-aperture and macro-pixel in the context of the present invention are described above, wherein sub-aperture and macro-pixel are control concepts and are not necessarily physical entities. The division between sub-aperture and macro-pixel can be integrated into the control unit 15 and the processing unit 14, and does not necessarily need to be distinguished in the detection unit 12 itself.

[0080] According to a preferred embodiment of the present invention, for at least one sub-aperture, the processing unit 14 is configured to determine the spot distribution of the echo on the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture. Each macropixel includes multiple independently addressable detectors. Because each macropixel includes multiple independently addressable detectors, the electrical signal output by each detector can be determined for subsequent determination of the spot distribution.

[0081] Specifically, for example, for the at least one sub-aperture, the processing unit 14 can determine the Geiger avalanche probability or Geiger avalanche count distribution of the detector in the preset area of ​​the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture, and determine the spot distribution of the echo on the macropixel based on the Geiger avalanche probability or Geiger avalanche count distribution. Based on the current light-clearance size of the sub-aperture, according to the aforementioned relationship, the preset area is determined by the light-clearance size of the sub-aperture corresponding to the macropixel, the focal length f of the receiving lens, the distance d between the detection unit and the aperture array, and the aperture of the receiving lens. Therefore, the corresponding area on the macropixel, i.e., the preset area, can be conveniently obtained. For a single detector within the preset area, a single exposure (e.g., corresponding to the Geiger avalanche probability for a single-photon detector) is generally not meaningful. Instead, the intensity distribution of the spot on the SPAD is typically determined by the superposition of multiple exposures (multiple frames) (i.e., corresponding to the Geiger avalanche count). Figure 7A and 7B The superposition effect of 100 exposures for a 50*50 detector array is shown, as three-dimensional and two-dimensional images respectively.

[0082] When the light transmission area of ​​the sub-aperture matches the focal spot, the distribution of the number of detector excitations in the preset area of ​​the corresponding macro pixel (for example, the result of multiple exposure superposition as shown in FIG7 ) is as follows: Figure 8 As shown, the middle part in the corresponding area has a relatively flat part, and both sides have inclined rising edges and falling edges, and the slopes of the rising edges and falling edges are not too large, for example, the absolute value is less than a preset threshold. Figure 8 The distribution diagram shown can be considered as a standard signal.

[0083] When the light passing area of ​​the sub-aperture is larger than the size of the focal spot, such as Figure 9As shown, the Geiger avalanche probability or Geiger avalanche count of the detectors at the edge of the detector array in the preset area of ​​the macropixel corresponding to the sub-aperture (the dotted line range in the figure corresponds to the preset area) will not increase due to the echo laser irradiation, and there is a blank area. The Geiger avalanche count of the SPAD can be obtained by, for example, accumulating the data of each addressable SPAD at a certain time through an accumulator. Figure 9 As shown, there is a flat portion in the middle of the distribution graph, and inclined rising edges and falling edges on both sides, which are symmetrical, and there is a blank area outside the rising edge and the falling edge.

[0084] When the position of the light-transmitting area of ​​the sub-aperture is offset from the focal spot, the distribution of the number of Geiger avalanches occurring in the detector array of the preset area of ​​the macro-pixel corresponding to the sub-aperture will be asymmetric. Figure 10 As shown, there is a flat portion in the middle of the distribution graph, and the rising edges and falling edges on both sides of the flat portion are asymmetrical.

[0085] When the light transmission area of ​​the sub-aperture is smaller than the focal spot, the probability or number of Geiger avalanches occurring in the detectors at the edge of the detector array in the preset area of ​​the macro-pixel corresponding to the sub-aperture is higher. Figure 11 As shown, there is a flat portion in the middle of the distribution graph, and the slopes of the rising edges and falling edges on both sides of the flat portion are very high, for example, the absolute values ​​are higher than a preset threshold.

[0086] Therefore, the processing unit can determine the Geiger avalanche probability or the number of Geiger avalanches of the detector in a preset area on the macropixel based on the electrical signal output by the detector in the macropixel, and then determine whether one or more of the size, position and shape of the current light-transmitting area of ​​the sub-aperture is appropriate based on the Geiger avalanche probability or the Geiger avalanche number of the detector.

[0087] As mentioned above, Figure 8 The distribution diagram shown can be considered as a standard signal. For the at least one sub-aperture, the control unit 15 is configured to control the optical switching pixels of the sub-aperture so that the Geiger avalanche number distribution of the detector in the preset area of ​​the macro pixel corresponding to the sub-aperture is substantially consistent with the standard distribution.

[0088] Specifically, for the at least one sub-aperture, the control unit is configured to control the optical switching pixel of the sub-aperture according to the deviation between the Geiger avalanche number distribution of the detector in the preset area of ​​the macro pixel corresponding to the sub-aperture and the standard distribution. For example, when the distribution diagram of the Geiger avalanche number obtained by the processing unit is Figure 9 When the distribution diagram shown in FIG. 1 is obtained, the light-passing area of ​​the sub-aperture can be reduced to reduce or eliminate the blank area; when the distribution diagram of the number of Geiger avalanches obtained by the processing unit is Figure 10When the distribution diagram is shown, the sub-aperture can be increased on the side with higher slope ( Figure 10 The distribution of the number of Geiger avalanches obtained by the processing unit is Figure 11 When the distribution diagram is shown, the through-hole area of ​​the sub-aperture on both sides can be increased. Figure 8-11 The detection unit 2 and the aperture array 13 are shown in a one-dimensional form. Those skilled in the art will readily appreciate that the above description is also applicable to a two-dimensional array of detection units 2 and aperture array 13.

[0089] According to a preferred embodiment of the present invention, the aperture array can be configured as an attenuation plate with adjustable transmittance, and the control unit is configured to initialize the aperture array according to a configuration file. Each sub-aperture can have a corresponding configuration file, and upon device startup or initialization, or during the first detection, the sub-aperture can be configured according to the configuration file.

[0090] In some cases, configuration files may be missing or incorrect. During radar startup, reset, or software upgrades, if the sub-aperture configuration files for one or more channels are missing or incorrect, the sub-aperture for that channel can be configured as a uniform attenuation plate with adjustable transmittance. Taking the liquid crystal aperture array and SPAD array as an example, the transmittance of the liquid crystal can be set to a low value, such as T = 10%, in the initial state. The avalanche state of the SPAD array of the macropixel corresponding to that channel is then read. If a valid echo spot is obtained, the sub-aperture opening of that channel can be configured based on the position, size, and shape of the detected echo spot, thus updating the configuration file.

[0091] refer to Figure 12 Detailed description. At this time, the aperture array 13 or one of its sub-apertures is configured as an attenuation plate, wherein each of the optical switch pixels allows light to pass through at a certain attenuation rate and illuminate the detection unit 12. At this time, the Geiger avalanche number of the detector on the detection unit 12 will show a certain area. Figure 8 Further, based on this area, according to Figure 5 The relationship between the size L2 of the illuminated area on the macro pixel and the corresponding light-transmitting area size L1 of the sub-aperture, the focal length f of the receiving lens, and the distance d between the detection unit and the aperture array can easily determine the required light-transmitting area of ​​the sub-aperture.

[0092] Figure 13 A flow chart of a method 200 for initializing a sub-aperture and adjusting a light-passing area of ​​the sub-aperture is shown, wherein the detector is a SPAD and the aperture array is a liquid crystal aperture array, that is, each optical switch pixel is a liquid crystal unit. Detailed description is given below with reference to the accompanying drawings.

[0093] In step S201, the system starts initialization.

[0094] In step S202, all liquid crystal cells are turned off.

[0095] In step S203, it is checked whether there is an initial configuration file of the light-transmitting area of ​​the sub-aperture. If so, the process proceeds to step S207; otherwise, the process proceeds to step S204.

[0096] In step S204, the light flux of the liquid crystal is increased, for example, the liquid crystal aperture is set as an attenuation plate. Preferably, the initial increase is small, for example, 10%.

[0097] In step S205, a determination is made as to whether the size, position, and shape of the echo spot can be effectively measured by the SPAD array of the macropixel in the receiving channel. If so, the process proceeds to step S206. Otherwise, the process returns to step S204 and continues to increase the light flux through the liquid crystal until the size, position, and shape of the echo spot can be effectively measured in step S205.

[0098] In step S206 , the size, position and shape of the corresponding light-transmitting area of ​​the sub-aperture are inferred based on the size, position and shape of the echo spot effectively measured, and a light-transmitting area profile of the sub-aperture is set accordingly.

[0099] In step S207 , the light transmission area of ​​the sub-aperture is set according to the configuration file.

[0100] In step S208, a determination is made as to whether the size, position, and shape of the SPAD array echo spot detected by the preset area of ​​the macropixel of the receiving channel matches the size, position, and shape of the light-transmitting area of ​​the sub-aperture. If so, step S208 is repeated to continue detection; otherwise, the process proceeds to step S209.

[0101] In step S209 , the size, position and shape of the light-transmitting area of ​​the liquid crystal diaphragm are configured according to the size, position and shape of the echo spot measured by the SPAD array of the preset area of ​​the macro pixel of the receiving channel.

[0102] In the preferred embodiment of the present invention, the mechanical pinhole diaphragm is replaced with a liquid crystal diaphragm. By electrically controlling the optical rotation properties of the liquid crystal cells, addressable cell states such as open, closed, and half-open can be achieved. The liquid crystal diaphragm is placed in the focal plane of the receiving lens. Because each liquid crystal cell is addressable and controllable, the corresponding aperture's light transmission area can be dynamically adjusted based on the focal plane spot shape of each channel to achieve optimal receiving field of view and stray light suppression. The dynamic response rate of the liquid crystal device ranges from tens of kHz to tens of Hz, meeting the dynamic diaphragm adjustment requirements of area array radars.

[0103] When ambient light is too strong, such as direct sunlight, the SPADs are attenuated by controlling the angle of the liquid crystal to achieve partial light transmission. While this also reduces the efficiency of the returning laser light, it prevents the SPADs from saturating and failing under strong light. Reducing ranging capability to prevent ranging failure in strong background light conditions is a reasonable radar configuration.

[0104] The embodiments of the present invention address the issue of spot shift at different distances under paraxial optical conditions, address the received spot shift caused by mechanical deformation, and address alignment issues during production. Furthermore, the preferred embodiments of the present invention do not change the number of SPAD units read per channel, nor do they reduce the channel's dynamic response range. Furthermore, the present invention addresses the saturation issue of SPAD devices under strong light.

[0105] like Figure 14 As shown, the present invention also relates to a laser radar 300, comprising a transmitting unit 301 and a receiving unit 302. The transmitting unit 301 comprises at least one laser configured to emit a probing laser beam for detecting a target. The laser preferably comprises a vertical cavity surface emitting laser (VCSEL). The receiving unit 302 comprises the detection device 10 described above, configured to receive an echo of the probing laser beam after it is reflected from a target and to process the echo signal.

[0106] According to a preferred embodiment of the present invention, a laser of the transmitting unit and a macro pixel of the receiving unit and the sub-aperture corresponding to the macro pixel constitute a detection channel. The laser array in the transmitting unit 301 and the detection unit 12 are, for example, Figure 1 The area array shown, such as one composed of VCSEL lasers, is also addressable and controllable. Furthermore, the aforementioned laser can include a single light-emitting unit or a structure composed of multiple, simultaneously emitting small units. The lidar's multiple detection channels (e.g., controlled to follow a specific time sequence) perform detection, with each detection channel adjusting its sub-aperture in real time based on the macropixel readout to achieve ambient light suppression.

[0107] like Figure 15 As shown, the present invention further relates to a detection method 400, which is described in detail below with reference to the accompanying drawings.

[0108] In step S401, the echo of the laser beam reflected on the target object is focused by a receiving lens. Figure 3 The receiving lens 11 shown includes a single lens or a lens group, and is used to converge the echo.

[0109] In step S402, a light-transmitting area is provided by an aperture array, wherein the aperture array is located on or near the focal plane of the receiving lens, and the aperture array includes at least one sub-aperture, each sub-aperture includes a plurality of independently controllable optical switch pixels, and each sub-aperture is configured so that one or more of the optical switch pixels are turned on to form the light-transmitting area, so as to allow the echo from the receiving lens to pass through. The aperture array is, for example, Figure 3 The aperture array 13 shown is arranged on or near the focal plane of the receiving lens 11 and includes one or more sub-apertures.

[0110] In step S403, the echo passing through the light-transmitting area is received by a detection unit, the detection unit includes at least one macro-pixel, each macro-pixel includes an array composed of multiple detectors, and the echo passing through the light-transmitting area of ​​a sub-aperture is irradiated on a corresponding macro-pixel of the detection unit and converted into an electrical signal. The detection unit is, for example, Figure 3 The detection unit 12.

[0111] In step S404 , according to the light spot distribution on the macro pixel corresponding to at least one sub-aperture in the aperture array, the opening and closing of the optical switch pixel of the sub-aperture is controlled.

[0112] According to a preferred embodiment of the present invention, in step S104, for at least one sub-aperture, the light switch pixels of the sub-aperture are controlled according to the spot distribution of the echo on the macro pixel corresponding to the sub-aperture, so that the spot distribution of the echo on the sub-aperture is substantially consistent with the light transmission area of ​​the sub-aperture, for example Figure 6A 、 6B and the effect achieved by 6C.

[0113] According to a preferred embodiment of the present invention, in step S104: for the at least one sub-aperture, the spot distribution of the echo on the macropixel corresponding to the sub-aperture is determined based on the electrical signal output by the macropixel corresponding to the sub-aperture, and the multiple detectors included in each macropixel are independently addressable.

[0114] According to a preferred embodiment of the present invention, step S104 further includes: for the at least one sub-aperture, determining the Geiger avalanche number distribution of the detector in a preset area of ​​the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture, and determining the spot distribution of the echo on the macropixel based on the Geiger avalanche number distribution.

[0115] According to a preferred embodiment of the present invention, in step S104, for the at least one sub-aperture, the optical switch pixels of the sub-aperture are controlled so that the Geiger avalanche number distribution of the detector in the preset area of ​​the macro pixel corresponding to the sub-aperture is substantially consistent with the standard distribution, where the standard distribution is, for example, Figure 8 described.

[0116] According to a preferred embodiment of the present invention, in step S104, for the at least one sub-aperture, the optical switch pixels of the sub-aperture are controlled based on the deviation of the Geiger number distribution of the detector in the preset area of ​​the macropixel corresponding to the sub-aperture from the standard distribution, so that the Geiger avalanche number distribution of the detector is as close to or as consistent as possible with the standard distribution.

[0117] According to a preferred embodiment of the present invention, the detection method 400 further includes initializing the aperture array, for example, initializing the aperture array according to a configuration file; when the configuration file is missing, configuring the aperture array as an attenuation plate with adjustable transmittance, updating the configuration file according to the size, position and shape of the light spot of the echo on the detection unit, and the correspondence between the light spot and the aperture array, and then initializing the aperture array according to the configuration file, which can be achieved by Figure 13 Initialize according to the process shown.

[0118] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A detection device comprising: a receiving lens configured to receive and focus an echo of the detection laser beam reflected on a target object; a detection unit configured to receive the echo and output an electrical signal, the detection unit comprising at least one macropixel, each macropixel comprising an array consisting of a plurality of detectors, and the plurality of detectors included in each macropixel being independently addressable; an aperture array, disposed between the receiving lens and the detection unit, located on or near the focal plane of the receiving lens, the aperture array comprising at least one sub-aperture, each sub-aperture comprising a plurality of independently controllable optical switch pixels, wherein one sub-aperture corresponds to one macro-pixel, forming a receiving channel; each sub-aperture is configured such that one or more of the optical switch pixels are turned on to form a light-transmitting area, thereby allowing an echo from the receiving lens to pass through and illuminate a corresponding macro-pixel of the detection unit; a processing unit configured to perform calculations and processing based on the electrical signal, A control unit is coupled to the aperture array and the processing unit and is configured to control each sub-aperture in the aperture array, and for at least one of the sub-apertures, control the opening and closing of the optical switch pixel of the sub-aperture according to the spot distribution of the echo on the macro pixel corresponding to the sub-aperture.

2. The detection device according to claim 1 , wherein, for the at least one sub-aperture, the control unit is configured to control the light switch pixels of the sub-aperture based on the spot distribution of the echo on the macropixel corresponding to the sub-aperture, so that the spot distribution of the echo on the sub-aperture is substantially consistent with the light transmission area of ​​the sub-aperture.

3. The detection device according to claim 2, wherein for the at least one sub-aperture, the processing unit is configured to determine the spot distribution of the echo on the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture.

4. The detection device according to claim 3, wherein, for the at least one sub-aperture, the processing unit determines a Geiger avalanche number distribution of the detector in a preset area of ​​the macropixel based on the electrical signal output by the macropixel corresponding to the sub-aperture, and determines a spot distribution of the echo on the macropixel based on the Geiger avalanche number distribution.

5. The detection device according to claim 4, wherein the preset area is determined by the light-transmitting area of ​​the sub-aperture corresponding to the macro pixel, the focal length f of the receiving lens, and the distance d between the detection unit and the aperture array.

6. The detection device according to claim 5 , wherein for the at least one sub-aperture, the control unit is configured to control the optical switching pixels of the sub-aperture so that the Geiger avalanche number distribution of the detector in the preset area of ​​the macropixel corresponding to the sub-aperture is substantially consistent with the standard distribution.

7. The detection device according to claim 5 , wherein for the at least one sub-aperture, the control unit is configured to control the optical switching pixels of the sub-aperture according to the deviation of the Geiger avalanche number distribution of the detector in the preset area of ​​the macro-pixel corresponding to the sub-aperture from the standard distribution.

8. The detection device according to any one of claims 1 to 7, wherein the detector comprises a single-photon detector, and the aperture array comprises a liquid crystal aperture or an electrically controlled filter.

9. The detection device according to any one of claims 1 to 7, wherein the aperture array can be configured as an attenuation plate with adjustable transmittance, and the control unit is configured to initialize the aperture array according to a configuration file.

10. The detection device as claimed in claim 9, wherein the control unit is configured to: when the configuration file is missing, configure the aperture array as an attenuation plate, and update the configuration file according to the size, position and shape of the light spot of the echo on the detection unit, and the correspondence between the light spot and the aperture array.

11. A detection method comprising: S401: Converging the detection laser beam through a receiving lens to detect the echo reflected by the target object; S402: Providing a light-clearance area by using an aperture array, wherein the aperture array is located on or near the focal plane of the receiving lens, the aperture array includes at least one sub-aperture, each sub-aperture includes a plurality of independently controllable optical switch pixels, and each sub-aperture is configured such that one or more of the optical switch pixels are turned on to form the light-clearance area, thereby allowing the echo from the receiving lens to pass through; S403: Receiving, by a detection unit, an echo that passes through the light-transmitting area. The detection unit includes at least one macropixel, each macropixel includes an array consisting of a plurality of detectors, and the plurality of detectors included in each macropixel are independently addressable. One sub-aperture corresponds to one macropixel, forming one receiving channel. An echo that passes through the light-transmitting area of ​​one sub-aperture is irradiated onto a corresponding macropixel of the detection unit and converted into an electrical signal. S404: Controlling the opening and closing of the optical switch pixel of at least one sub-aperture in the aperture array according to the light spot distribution on the macro pixel corresponding to the sub-aperture.

12. The detection method according to claim 11, wherein the step S404 comprises: For the at least one sub-aperture, the light switch pixels of the sub-aperture are controlled according to the spot distribution of the echo on the macropixel corresponding to the sub-aperture, so that the spot distribution of the echo on the sub-aperture is substantially consistent with the light transmission area of ​​the sub-aperture.

13. The detection method according to claim 12, wherein the step S404 comprises: For the at least one sub-aperture, the spot distribution of the echo on the macro-pixel is determined according to the electrical signal output by the macro-pixel corresponding to the sub-aperture.

14. The detection method according to claim 13, wherein the step S404 further comprises: For the at least one sub-aperture, the Geiger avalanche number distribution of the detector in a preset area of ​​the macropixel is determined based on the electrical signal output by the macropixel corresponding to the sub-aperture, and the spot distribution of the echo on the macropixel is determined based on the Geiger avalanche number distribution.

15. The detection method according to claim 14, wherein the preset area is determined by the light-transmitting area of ​​the sub-aperture corresponding to the macro pixel, the focal length f of the receiving lens, and the distance d between the detection unit and the aperture array.

16. The detection method according to claim 15, wherein the step S404 comprises: For the at least one sub-aperture, the optical switch pixels of the sub-aperture are controlled so that the Geiger avalanche number distribution of the detector in the preset area of ​​the macro pixel corresponding to the sub-aperture is substantially consistent with the standard distribution.

17. The detection method according to claim 15, wherein the step S404 comprises: For the at least one sub-aperture, the optical switch pixels of the sub-aperture are controlled according to the deviation between the Geiger avalanche number distribution of the detector in the preset area of ​​the macro-pixel corresponding to the sub-aperture and the standard distribution.

18. The detection method according to any one of claims 11 to 17, further comprising: Initialize the aperture array.

19. The detection method according to claim 18, wherein the step of initializing the aperture array comprises: The aperture array is initialized according to a configuration file. When the configuration file is missing, the aperture array is configured as an attenuation plate with adjustable transmittance. The configuration file is updated according to the size, position, and shape of the light spot of the echo on the detection unit, as well as the correspondence between the light spot and the aperture array, and the aperture array is initialized again according to the configuration file.

20. A laser radar comprising: a transmitting unit, comprising at least one laser, configured to emit a detection laser beam for detecting a target object; A receiving unit, wherein the receiving unit comprises the detection device according to any one of claims 1 to 10, wherein the detection device is configured to receive an echo after the detection laser beam is reflected on a target object and process the echo signal.

21. The laser radar as claimed in claim 20, wherein a laser of the transmitting unit, a macro pixel of the receiving unit and the sub-aperture corresponding to the macro pixel constitute a detection channel.

22. The laser radar of claim 20 or 21, wherein the laser comprises a vertical cavity surface emitting laser.

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