A depth imaging method and a depth imaging system

Abstract

The present application discloses a depth imaging method and a depth imaging system. The target object is scanned at different scanning angles, and laser pulses are emitted at a pulse emission cycle at each scanning angle; the photoelectric detection unit on the photoelectric sensor is polled and controlled to be turned on and off in each pulse emission cycle; each photoelectric detection unit of the photoelectric sensor is divided into multiple super-resolution pixels according to the size of the laser spot; the depth information of the laser spot at the current scanning angle is obtained according to the electrical signal provided by each photoelectric detection unit that is polled and turned on in the pulse emission cycle; after the target object is scanned, the depth information of the laser spot at each scanning angle is spliced ​​to obtain a super-resolution depth image of the target object. The technical solution of the present application greatly shortens the cumulative exposure time of the photoelectric detection unit on the photoelectric sensor, reduces power consumption, and improves the frame rate and imaging speed; the converted signal has a high signal-to-noise ratio, which is beneficial to improving the imaging quality of the depth image of the target object.

Description

Technical Field

[0001] The present application relates to the field of imaging technology, and in particular to a depth imaging method and a depth imaging system. Background Art

[0002] With the advancement of technology, computer vision has been widely applied in our daily lives and across various industries, such as geographic mapping and imaging, remote sensing, autonomous driving, collaborative robotics, three-dimensional depth measurement, and consumer electronics. Radar is a key technology for implementing computer vision. Radar includes but is not limited to lidar, millimeter-wave radar, and visible light radar. A 3D camera is an example application of a radar system. This example system consists of a laser pulse transmitter, a laser pulse receiver, a time-to-digital converter (TDC), and a control system.

[0003] In a radar operating scenario, a laser pulse transmitter generates a light pulse and transmits it into the environment. After reflecting off a target object, the light pulse is picked up by a receiver. The receiver converts the received photons into electrical signals and feeds them to a time-determining device (TDC). The TDC quantifies the time delay of the returning photons relative to the pulse's emission time and places them into a time grid of a given width. When a sufficient number of pulses are transmitted, the number of events in the time grid forms a histogram. The highest position in the histogram corresponds to the pulse's time of flight (TOF), which can be used to calculate the distance to the target object.

[0004] Photoelectric sensors typically serve as receivers to detect light pulses. Depth imaging is widely used in fields such as computer vision. As the demand for depth imaging applications continues to grow, the demand for higher resolution is also increasing. However, due to limitations in semiconductor processing and size, the resolution of the photodetection unit in photoelectric sensors is difficult to meet practical requirements.

[0005] Currently, dot-matrix super-resolution technology can address the conflict between the high-resolution requirements of depth imaging and the low-resolution performance of photoelectric sensors. This technology creates virtual, smaller super-resolution pixels based on the original resolution of the photoelectric sensor, thereby increasing the resolution of the photoelectric sensor to meet the high-resolution requirements of depth imaging. The transceiver modules of 3D cameras used for depth imaging typically have a certain baseline distance, resulting in a mismatch between the transceiver and receiver positions. This mismatch offset is also known as parallax. Parallax is measured in terms of the number of photoelectric detection cells and varies with target distance. Due to parallax, the photoelectric sensor cannot determine the location of the photoelectric detection cell where the laser spot is located when the target distance is unknown. Therefore, it is often necessary to enable all surrounding photoelectric detection cells to detect the photoelectric detection cell that received the pulse. However, in strong ambient light, the power consumption of fully enabling all photoelectric detection cells is unsustainable for the chip. Furthermore, due to the limited number of TDCs, multiple photoelectric detection cells share a single TDC. When all photoelectric detection cells are enabled, only one detects the target signal, while the remaining photoelectric detection cells detect noise. This significantly reduces the signal-to-noise ratio of the TDC received signal, making it difficult to determine the signal light from the histogram.

[0006] Currently, the location of the light spot can be detected by activating the photodetection units in a time-sharing manner. With this time-sharing approach, each photodetection unit is exposed for a specific duration. However, this detection method requires a high number of exposures and long exposure times, resulting in very high system power consumption, a reduced frame rate, and slow depth imaging. To reduce the number and duration of exposures, multiple photodetection units must be fully activated simultaneously, reducing the signal-to-noise ratio of the histogram and, therefore, the probability of detecting the signal light. Summary of the Invention

[0007] The present application provides a depth imaging method and a depth imaging system to reduce system power consumption while ensuring the signal-to-noise ratio, achieve high frame rate dot matrix super-resolution, and improve the speed of depth imaging.

[0008] In a first aspect, the present application provides a depth imaging method, comprising:

[0009] Scanning the target object at different scanning angles, and emitting laser pulses at a pulse emission cycle at each scanning angle;

[0010] Polling and controlling the opening and closing of a photoelectric detection unit on a photoelectric sensor in each pulse emission cycle; the photoelectric sensor includes a plurality of photoelectric detection units, each of which is divided into a plurality of super-resolution pixels according to the size of the laser spot;

[0011] According to the electrical signals provided by each photoelectric detection unit that is turned on in a polling cycle during the pulse emission period, the depth information of the laser spot at the current scanning angle is obtained;

[0012] After scanning the target object, the depth information of the laser spot at each scanning angle is spliced ​​to obtain a super-resolution depth image of the target object.

[0013] Optionally, polling and controlling the photoelectric detection unit on the photoelectric sensor to be turned on and off in each pulse emission cycle specifically includes:

[0014] Determining the photoelectric detection unit to be polled in each pulse emission cycle;

[0015] Determining a time window corresponding to each of the photoelectric detection units to be polled;

[0016] Each of the photoelectric detection units to be polled is controlled to be turned on and off according to the time window polling.

[0017] Optionally, emitting laser pulses at each scanning angle in a pulse emission cycle specifically includes:

[0018] emitting laser pulses toward the target object in a dot matrix projection manner for a plurality of pulse emission cycles at each scanning angle, so as to simultaneously form a plurality of laser spots on the photoelectric sensor;

[0019] The step of determining the photoelectric detection unit to be polled in each pulse emission cycle specifically includes:

[0020] Obtain the minimum interval between two adjacent laser spots in the field of view of the laser;

[0021] The photoelectric detection unit to be polled corresponding to each laser spot in each pulse emission cycle is determined according to the photoelectric detection unit without parallax and the minimum interval.

[0022] Optionally, obtaining the minimum interval between two adjacent laser spots in the field of view of the laser specifically includes:

[0023] The minimum interval between two adjacent laser spots in the field of view of the laser is obtained according to the baseline distance between the laser and the photoelectric sensor, the minimum detection distance of the photoelectric sensor, the lateral field angle and the lateral resolution of the photoelectric detection unit.

[0024] Optionally, determining the time window corresponding to each photoelectric detection unit to be polled specifically includes:

[0025] determining an offset range of each of the photodetection units to be polled relative to the photodetection unit without parallax;

[0026] Determining, according to the offset range and the correspondence between the offset and the distance, a distance range corresponding to when the laser spot falls on each of the photoelectric detection units to be polled;

[0027] According to the distance range and the corresponding relationship between the distance and the time delay, the flight time range within which each photoelectric detection unit to be polled can receive the laser spot is determined; the flight time range serves as the time window.

[0028] Optionally, the depth information of the laser spot at the current scanning angle is obtained according to the electrical signals provided by each photoelectric detection unit that is turned on in a polling cycle during the pulse emission period, specifically including:

[0029] Generate a direct time-of-flight histogram corresponding to the current scanning angle according to the electrical signals provided by each photoelectric detection unit that is turned on during the pulse emission period at the current scanning angle;

[0030] Finding a peak in the direct flight time histogram to determine the flight time corresponding to the laser spot at the current scanning angle;

[0031] According to the flight time and the corresponding relationship between the flight time and the distance, the distance information of the laser spot at the current scanning angle is obtained as the depth information of the laser spot.

[0032] Optionally, after obtaining the distance information of the laser spot at the current scanning angle as the depth information of the laser spot, the method further includes:

[0033] An offset corresponding to the distance information is obtained according to a correspondence between the offset and the distance; the integer part of the offset indicates the number of photoelectric detection units that the target photoelectric detection unit is offset from the photoelectric detection unit without parallax, the target photoelectric detection unit being the photoelectric detection unit where the laser spot is located, and the decimal part of the offset indicates the super-resolution position of the target photoelectric detection unit where the laser spot is received;

[0034] Determining, based on the offset and the super-resolution multiple of the photoelectric sensor, the super-resolution pixel at which the laser spot is detected in the target photoelectric detection unit at the current scanning angle, so as to establish a corresponding relationship between the depth information and the super-resolution pixel;

[0035] After scanning the target object, stitching the depth information of the laser spot at each scanning angle specifically includes:

[0036] After the target object is scanned, the depth information of the laser spot at each scanning angle is spliced ​​together using the correspondence between the depth information and the super-resolution pixels.

[0037] Optionally, scanning the target object at different scanning angles includes:

[0038] Before scanning the target object at a next scanning angle, the laser light path is adjusted to form the next scanning angle.

[0039] In a second aspect, the present application provides a depth imaging system, comprising: a laser, a controller, a gate switch, a photoelectric sensor, a time-to-digital converter, and a processor; the controller is connected to the laser; the photoelectric sensor includes a plurality of photoelectric detection units, each photoelectric detection unit is divided into a plurality of super-resolution pixels according to the size of the laser spot; the gate switch is connected to all the photoelectric detection units of the photoelectric sensor; the controller and the processor are respectively connected to the time-to-digital converter; the time-to-digital converter is further connected to the photoelectric detection unit through the gate switch;

[0040] The controller is used to control the laser to scan the target object at different scanning angles, and emit laser pulses at a pulse emission cycle at each scanning angle;

[0041] The gate switch is used to poll and control the photoelectric detection unit on the photoelectric sensor to turn on and off in each pulse emission cycle; the turned-on photoelectric detection unit is used to receive the light signal reflected by the target object and convert the light signal into an electrical signal;

[0042] The time-to-digital converter is used to obtain the flight time based on the electrical signals provided by each photoelectric detection unit that is polled and turned on during the pulse emission period and the emission time of each pulse at the current scanning angle, and convert the flight time into a count value;

[0043] The processor is used to form a direct flight time histogram corresponding to the current scanning angle based on the count value converted by the time-to-digital converter and the electrical signal; obtain the depth information of the laser spot at the current scanning angle based on the direct flight time histogram; after the laser completes scanning the target object, splice the depth information of the laser spot at each scanning angle to obtain a super-resolution depth image of the target object.

[0044] Optionally, the laser includes: a laser light source, a collimating lens, a deflecting mirror, a beam splitter element and a driving device;

[0045] The laser light source is used to emit a laser beam, and the laser beam includes laser pulses emitted according to a pulse emission period;

[0046] The collimating lens is used to collimate the laser beam and send it to the deflecting mirror;

[0047] The deflection mirror is connected to the driving device and is used to reflect the laser beam from the collimating lens to the beam splitting element; during this period, the deflection mirror is driven by the driving device to perform periodic deflection;

[0048] The beam splitting element is used to split the received laser beam into multiple beams and then project the multiple laser beams toward the target object.

[0049] It can be seen from the above technical solutions that the embodiments of the present application have at least the following advantages:

[0050] In the depth imaging method provided by the present application, a target object is scanned at different scanning angles, and a laser pulse is emitted at each scanning angle in a pulse emission cycle; a photodetection unit on a photoelectric sensor is polled and controlled to be turned on and off during each pulse emission cycle; the photoelectric sensor includes multiple photodetection units, each of which is divided into multiple super-resolution pixels according to the size of the laser spot; the depth information of the laser spot at the current scanning angle is obtained based on the electrical signal provided by each photodetection unit that is polled and turned on during the pulse emission cycle; after the target object is scanned, the depth information of the laser spot at each scanning angle is spliced ​​to obtain a super-resolution depth image of the target object. Since the photodetection units are polled and turned on during each pulse emission cycle, the cumulative exposure time of the photodetection units on the photoelectric sensor is greatly shortened compared to the time-sharing method of turning on the photodetection units, thereby reducing power consumption and improving the frame rate and depth imaging speed. In addition, compared to the method of turning on all photodetection units at the same time, the polling method ensures that the photodetection units turned on at a certain time are not interfered with by other adjacent photodetection units, and the converted signal has a higher signal-to-noise ratio, thereby ensuring a higher probability of detecting effective signals, which is conducive to improving the imaging quality of the depth image of the target object. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A schematic diagram of lattice super-resolution;

[0052] Figure 2 Schematic diagram of the relationship between the transmitting field of view and the receiving field of view;

[0053] Figure 3 It is a schematic diagram of the relationship between offset and distance;

[0054] Figure 4 Schematic diagram of the actual size of the field of view of a single photoelectric detection unit in the RX field of view at various distances;

[0055] Figure 5 A flowchart of a depth imaging method provided in an embodiment of the present application;

[0056] Figure 6 A schematic diagram of a laser dot matrix projection;

[0057] Figure 7 Schematic diagram of the position change of multiple laser spots in super-resolution pixels when the scanning angle changes according to an embodiment of the present application;

[0058] Figure 8A schematic diagram of the offset range of other photoelectric detection units relative to the photoelectric detection unit without parallax in the lateral direction provided by an embodiment of the present application;

[0059] Figure 9 A schematic diagram of the polling timing of each photoelectric detection unit SPAD0 to SPAD4 to be polled within a pulse transmission cycle provided in an embodiment of the present application;

[0060] Figure 10 A schematic diagram of a direct time-of-flight histogram provided in an embodiment of the present application;

[0061] Figure 11 A schematic diagram of a dot matrix emission parallax provided in an embodiment of the present application;

[0062] Figure 12 A flowchart of another depth imaging method provided in an embodiment of the present application;

[0063] Figure 13 A schematic diagram of the structure of a depth imaging system provided in an embodiment of the present application;

[0064] Figure 14 A schematic diagram of the structure of a laser provided in an embodiment of the present application. DETAILED DESCRIPTION

[0065] When performing depth imaging, if the resolution of the photoelectric sensor is insufficient to meet the imaging requirements, dot matrix super-resolution technology can be used to improve the resolution. The following is a brief introduction to dot matrix super-resolution technology with reference to the accompanying figures.

[0066] Figure 1 is a schematic diagram of lattice super-resolution. Figure 1 As shown, the size of one photodetection unit corresponds to 4×4 super-resolution pixels, and the 4×4 photodetection units share one TDC. The size of the super-resolution pixels in the photodetection unit matches the size of the laser spot. For example, if the laser spot diameter is K, the photodetection unit is divided into multiple K×K super-resolution pixels. In addition, the laser spot diameter can also be slightly smaller than the super-resolution pixel size.

[0067] Figure 2 Schematic diagram of the relationship between the transmitting field of view and the receiving field of view. Figure 2 In the figure, TX represents the laser and RX represents the photoelectric sensor. The dotted line passing through TX represents the baseline of the laser, and the dotted line passing through RX represents the baseline of the photoelectric sensor. Figure 2 As shown in the figure, there is a certain distance between the baselines of TX and RX. Figure 2 In the figure, horizontal direction represents offset and vertical direction represents distance. Due to the existence of baseline distance, the sending and receiving positions of light are mismatched, and the offset of the mismatch (also known as parallax) is inversely proportional to the distance.

[0068] Figure 3 Schematic diagram of the relationship between offset and distance. In the embodiment of the present application, the offset is measured by the number of photoelectric detection units, for example: offset 3 photoelectric detection units. Taking the lateral offset as an example, the actual meaning is the lateral offset of the size of 3 photoelectric detection units. Figure 3 As shown, the farther the distance, the smaller the offset; the closer the distance, the larger the offset.

[0069] Formula (1) shows how the offset is calculated:

[0070]

[0071] In formula (1), σ represents the offset, d baseline represents the baseline distance, d spad The field of view of a single photoelectric detection unit corresponds to the size of the actual field of view at a given distance. As shown in formula (1), when the baseline distance is constant, the size of the field of view of a single photoelectric detection unit in the actual field of view is inversely proportional to the offset. Combined with the relationship between offset and distance, it can be seen that the size of the field of view of a single photoelectric detection unit in the actual field of view is directly proportional to the distance.

[0072] Figure 4 The actual size of the field of view of a single photodetection unit in the RX field of view at various distances is shown. Figure 3 As shown, the closer the distance to the RX is, the smaller the size of the single photodetection unit in the corresponding RX field of view is; and the farther the distance from the RX is, the larger the size of the single photodetection unit in the corresponding RX field of view is.

[0073] Formula (2) shows how to calculate the size of the field of view of a single photoelectric detection unit corresponding to the actual field of view:

[0074]

[0075] In formula (2), d spad Indicates the size of the field of view of a single photoelectric detection unit corresponding to the actual field of view, Dist represents the distance, FOV h Indicates the lateral field of view of the photoelectric detection unit, N h Indicates the lateral resolution of the photodetection unit.

[0076] Combining formula (1) and formula (2), we can get the relationship between offset and distance:

[0077]

[0078] The premise of dot matrix super-resolution is to know in advance the specific position of the light spot in the photoelectric detection unit to be super-resolution, without relying on the output of the photoelectric sensor. That is, the precise position of the light spot formed by the emitted laser pulse on the photoelectric sensor must be known in advance. At present, the time-sharing method of turning on the photoelectric detection unit requires turning on the photoelectric detection units that may detect the light spot in turn, and detecting whether there is a laser pulse in the histogram formed after these photoelectric detection units convert the signal, so as to determine the position of the light spot. However, time-sharing turning on means multiple exposure times and exposure times, which causes the system power consumption to increase exponentially and the frame rate to decrease exponentially. The other method of turning on all the photoelectric detection units at the same time is easy to detect a large amount of ambient light, which reduces the histogram signal-to-noise ratio. The effective signal is easily masked by the noise, making it difficult to detect the light pulse and thus difficult to determine the position of the light spot.

[0079] From the above description, it can be seen that when using dot matrix super-resolution technology for depth imaging, it is difficult to achieve both high imaging signal-to-noise ratio and low system power consumption.

[0080] Based on the above problems, a depth imaging method and a depth imaging system are provided in the present application. In the technical solution of the present application, the photoelectric detection unit on the photoelectric sensor is polled and controlled to turn on and off during each pulse emission cycle, which shortens the exposure time of the photoelectric detection unit and reduces the number of exposures. This saves system power consumption, improves the frame rate, and increases the depth imaging speed. In addition, the signal-to-noise ratio of the histogram is enhanced, and the detection rate of the effective signal is improved. To facilitate the understanding of the technical solution of the present application, the following detailed description is given in conjunction with the embodiments and drawings.

[0081] Method Example:

[0082] See also Figure 5 , which is a flow chart of a depth imaging method provided by an embodiment of the present application. Figure 5 As shown, the depth imaging method includes:

[0083] Step 501: Scan the target object at different scanning angles, and emit laser pulses at a pulse emission cycle at each scanning angle.

[0084] The target object refers to the object that needs to be presented in the depth imaging. Depending on the actual needs of the depth image, the target object may be a person, an animal, a building, etc. The type of target object is not limited here. In the embodiment of the present application, a laser is used to emit a light pulse to the target object, and then the photoelectric sensor receives the light pulse reflected from the target object. The laser has good collimation and forms a light spot when projected onto the target object. The photoelectric sensor specifically detects the light spot on the target object.

[0085] In practical applications, various types of lasers can be used, such as those operating in the infrared band or the visible light band. The detection band of the photoelectric sensor must match the operating band of the laser to effectively detect the resulting light spot.

[0086] To fully scan the target object for subsequent depth imaging, a 2D line scan can be performed on the target object. Since a 2D line scan can be split into several independent 1D line scans, the following description uses a horizontal 1D line scan as an example.

[0087] In the embodiment of the present application, the scanning angle of the laser to the target object is constantly changing. The scanning angle can be changed by adjusting the laser optical path inside the laser, or by adjusting the overall position of the laser without changing the laser optical path inside the laser. After the laser optical path is adjusted, the next scanning angle is formed, and then scanning is performed at the next scanning angle until the super-resolution scan covering the entire receiving field of view is completed. To improve scanning efficiency, the laser can be made to emit a laser dot matrix, so that when the laser pulse is emitted, multiple laser spots can be formed on the surface of the target object. Figure 6 A schematic diagram of laser dot matrix projection.

[0088] In an embodiment of the present application, the photoelectric sensor includes a plurality of photoelectric detection units. The photoelectric detection units on the photoelectric sensor are arranged in a horizontal and vertical pattern. The horizontal dimension of each photoelectric detection unit may be the same as the vertical dimension, or may be different from the vertical dimension. As an example, the photoelectric detection unit may be a single photon avalanche diode (SPAD) or an avalanche photon diode (APD). The specific type of the photoelectric detection unit is not limited here.

[0089] Each photodetection unit is divided into multiple super-resolution pixels based on the size of the laser spot. For example, if the laser spot diameter is D and the lateral and longitudinal dimensions of the photodetection unit are both 4D, each photodetection unit can be divided into 4*4 super-resolution pixels. Dividing the photodetection unit into multiple super-resolution pixels based on the size of the laser spot allows for subsequent depth imaging based on the depth information recorded when the spot is detected by each super-resolution pixel, thus meeting the high-resolution requirements for depth imaging.

[0090] For ease of understanding, the present application provides a schematic diagram of the position change of multiple laser spots in super-resolution pixels when the scanning angle changes, as shown in FIG. Figure 7 .exist Figure 7 The left and right sides of the are the position changes of the laser spots 001 to 002 in the super-resolution pixels of the photoelectric conversion unit of the photoelectric sensor under the two scanning angles. Figure 7 It can be seen that when the scanning angle changes once, the laser spots 001 to 002 are shifted laterally by one super-resolution pixel on the photosensor.

[0091] When scanning a target at different scanning angles, laser pulses are emitted at a preset pulse emission period at each scanning angle to accumulate enough photons to subsequently obtain depth information of the laser spot. The pulse emission period can be set according to actual needs, for example, setting the pulse emission period to 100ns.

[0092] Step 502: polling and controlling the photoelectric detection unit on the photoelectric sensor to turn on and off in each pulse transmission cycle.

[0093] When the scanning angle remains constant, the photoelectric sensor detects the position of the super-resolution pixel of the laser spot formed by the laser pulses emitted by the laser at different pulse emission periods. However, during the detection phase, the specific photoelectric detection unit that receives the light signal reflected from the laser spot and the specific super-resolution pixel on this photoelectric detection unit that receives the light signal reflected from the laser spot are unknown.

[0094] In this embodiment of the present application, in order to save power and improve frame rate and depth imaging speed, a scheme for controlling the on and off of the photodetection unit by polling is proposed. Specifically, as described in this step, the photodetection unit on the photoelectric sensor is polled and turned on and off during each pulse emission cycle.

[0095] In the above Figure 3 In the introduction, the farther the target object is, the smaller the offset between the TX field of view and the RX field of view. In the embodiment of the present application, the photoelectric detection unit can be pre-calibrated when the target distance is infinite and there is no parallax between TX and RX as a photoelectric detection unit without parallax. The position of the photoelectric detection unit without parallax is used as the reference position to measure the offset of other photoelectric detection units. Figure 8 , a schematic diagram of the offset range of other photoelectric detection units relative to the photoelectric detection unit without parallax in the horizontal direction. Figure 8 As shown, the offset range of the photoelectric detection unit Spad i is [σ i-1 , σ i ].

[0096] According to formula (3), the relationship between the offset of the photoelectric detection unit and the distance to the target object can be known. Therefore, combining formula (3) to obtain the offset range [σ i-1 , σ i ] corresponds to the distance range [d imin , d imax ], the upper limit of the distance range d imax and the lower limit d imin The expression is as follows:

[0097]

[0098]

[0099] When performing depth imaging, the distance to the target object can be obtained by the flight time of the light pulse emitted by the laser. The relationship between distance and flight time is as follows:

[0100]

[0101] In formula (6), Δt represents the flight time and c represents the speed of light. Therefore, according to formulas (4) to (6), the distance range of the target object detected by the photoelectric detection unit [d i-1 , d i ] corresponds to the flight time range [t init_i , t end_i ], flight time range [t init_i , t end_i The lower and upper bounds of ] are expressed as follows:

[0102]

[0103]

[0104] Before polling and controlling the photodetection unit to be turned on within the pulse emission cycle, the photodetection unit to be polled can be first determined. The offset range of each photodetection unit to be polled relative to the photodetection unit without parallax is then determined, and the relationship between the offset and the distance is combined to obtain the distance range corresponding to when the laser spot falls on each photodetection unit to be polled. Based on the corresponding relationship between the distance and the time delay, the flight time range within which each photodetection unit to be polled can receive the laser spot is determined, and the flight time range is used as the time window for polling the photodetection unit. In this way, the time window corresponding to each photodetection unit to be polled is determined. Next, the turning on and off of each photodetection unit to be polled is controlled according to the time window.

[0105] by Figure 8 Taking the photoelectric detection unit Spad i shown in the figure as an example, the flight time range [t init_i , t end_i ], in each pulse emission cycle, t init_i As the moment to open Spad i, will t end_i As the moment to turn off Spad i. For ease of understanding, Figure 9 The polling timing of each photoelectric detection unit SPAD0 to SPAD4 to be polled within a pulse transmission cycle is shown as an example. Figure 9As shown, during the pulse transmission cycle, SPAD0 is controlled to turn on, SPAD0 is controlled to turn off (SPAD1 is controlled to turn on), SPAD1 is controlled to turn off (SPAD2 is controlled to turn on), SPAD2 is controlled to turn off (SPAD3 is controlled to turn on), SPAD3 is controlled to turn off (SPAD4 is controlled to turn on), and SPAD4 is controlled to turn off.

[0106] In this way, in each pulse emission cycle, each photoelectric detection unit to be polled is enabled only within the time window where it may detect the laser spot of the corresponding distance, thereby avoiding wasting exposure time and reducing the probability of detecting ambient light.

[0107] Step 503: Obtain the depth information of the laser spot at the current scanning angle according to the electrical signals provided by each photoelectric detection unit that is turned on in polling during the pulse emission period.

[0108] In conjunction with the aforementioned step 502, when a photodetection unit is turned on, it is possible to collect signal light or ambient light. In practical applications, among the multiple photodetection units that are polled and turned on to detect a laser spot within a pulse emission cycle, only one photodetection unit detects the laser spot. This photodetection unit is hereinafter referred to as the target photodetection unit. It is understandable that as the scanning angle changes, the target photodetection unit also changes. The target photodetection unit detects signal light (or signal light + ambient light), while the remaining photodetection units detect ambient light.

[0109] In order to obtain the depth image of the target object, the target photoelectric detection unit detects the specific depth information of the laser spot. The implementation process is described below:

[0110] Based on the electrical signals provided by each photodetector unit that is turned on during the pulse emission cycle at the current scanning angle, a direct time-of-flight histogram corresponding to the current scanning angle is generated. The horizontal axis of the direct time-of-flight histogram represents time, and the vertical axis represents count value. Figure 10 This is a schematic diagram of a direct time-of-flight histogram. By finding the peak in the histogram, the time corresponding to the column with the highest count value can be obtained, and this time is used as the flight time corresponding to the laser spot at the current scanning angle. Based on the flight time and the corresponding relationship between flight time and distance, as shown in formula (6), the flight time obtained from the histogram in the previous step is substituted into formula (6) to obtain the distance information of the laser spot at the current scanning angle. This distance information represents the depth information of the laser spot detected by the target photoelectric detection unit.

[0111] It should be noted that steps 501 to 503 are all executed in a loop.

[0112] Step 504: After scanning the target object, the depth information of the laser spot at each scanning angle is spliced ​​to obtain a super-resolution depth image of the target object.

[0113] Taking a one-dimensional line scan as an example, each change in the scanning angle changes the scanning position of the target object—that is, the position at which the same laser beam is transmitted to the target object changes. Furthermore, the position of the super-resolution pixel on the photosensor that receives the same laser spot changes laterally, with the change being one super-resolution pixel.

[0114] As described in step 503, the depth information of the laser spot is obtained at each scanning angle, so the complete super-resolution depth image of the target object can be obtained by stitching according to the position relationship between the super-resolution pixels receiving the laser spot at each scanning angle.

[0115] The above is the depth imaging method provided by the embodiment of the present application. In this method, the target object is scanned at different scanning angles, and laser pulses are emitted at each scanning angle in a pulse emission cycle; the photoelectric detection unit on the photoelectric sensor is polled and controlled to be turned on and off during each pulse emission cycle; the photoelectric sensor includes multiple photoelectric detection units, each of which is divided into multiple super-resolution pixels according to the size of the laser spot; the depth information of the laser spot at the current scanning angle is obtained based on the electrical signals provided by each photoelectric detection unit that is polled and turned on during the pulse emission cycle; after the target object is scanned, the depth information of the laser spot at each scanning angle is spliced ​​to obtain a super-resolution depth image of the target object.

[0116] Because the photodetection units are turned on in a polling manner within each pulse emission cycle, the cumulative exposure time of the photodetection units on the photoelectric sensor is greatly shortened compared to turning on the photodetection units in a time-sharing manner, thereby reducing power consumption and improving frame rate and depth imaging speed. In addition, compared to the method of turning on all photodetection units at the same time, the polling method ensures that the photodetection units turned on at a certain time are not interfered with by other nearby photodetection units. The converted signal has a higher signal-to-noise ratio, thereby ensuring a higher probability of valid signal detection, which is beneficial to improving the imaging quality of the depth image of the target object.

[0117] In polling-on mode, the time window during which each photodetector unit is enabled within a pulse emission cycle is precisely controlled, accurately receiving photons that may return at various distances and minimizing interference from ambient light. Because the number of ambient light photons collected during the time when multiple photodetector units are enabled within a pulse emission cycle is equivalent to the number collected during the time when a single photodetector unit is continuously enabled in the prior art, and the detection of signal light is equivalent to fully enabling all photodetector units, there is no signal loss and system power consumption is significantly reduced.

[0118] When using a laser to scan a target object, multiple laser beams can be projected simultaneously toward the target object to improve scanning efficiency. These laser beams can be emitted in parallel or non-parallel. The following description uses parallel emission as an example.

[0119] See also Figure 11 , this figure is a schematic diagram of dot matrix emission parallax. Figure 11 The solid dots in the middle represent different laser spots in the TX field of view, and the hollow circles represent different laser spots in the RX field of view. Figure 11 It's easy to see that if too many photodetectors are involved in a single polling control, it's possible to obtain two or more valid laser spot optical signals after polling. In this case, weaker optical signals can be easily misinterpreted as ambient light noise and ignored. To avoid this problem, the photodetectors to be polled based on a single laser spot can be determined before polling.

[0120] Another depth imaging method provided by an embodiment of the present application is described below in conjunction with the embodiments and drawings.

[0121] See also Figure 12 , which is a flow chart of another depth imaging method provided by an embodiment of the present application. Figure 12 As shown, the depth imaging method includes:

[0122] Step 1201: Scan the target object at different scanning angles, and emit laser pulses to the target object in a dot matrix projection manner for multiple pulse emission cycles at each scanning angle to simultaneously form multiple laser spots on the photoelectric sensor.

[0123] Multiple laser spots formed at different scanning angles are respectively Figure 7 The left side and Figure 7 on the right side.

[0124] Step 1202: Obtain the minimum interval between two adjacent laser spots in the field of view of the laser according to the baseline distance between the laser and the photoelectric sensor, the minimum detection distance of the photoelectric sensor, the lateral field angle and lateral resolution of the photoelectric detection unit.

[0125] The baseline distance between the laser and the photoelectric sensor can be determined through pre-calibration. Each photoelectric sensor's detection capability includes a maximum detection distance and a minimum detection distance. The minimum detection distance can be determined from the photoelectric sensor's factory specifications or through multiple tests. The photoelectric detection unit's lateral field of view and lateral resolution can also be determined from factory specifications.

[0126] In this embodiment, to determine the photodetector unit to be polled corresponding to each laser spot within each pulse emission cycle and to prevent more than one laser spot from being detected in a single polling cycle, the minimum separation between two adjacent laser spots in the laser's field of view (TX field of view) is first calculated. For each laser spot, the photodetector unit to be polled is determined based on the minimum separation.

[0127] The minimum interval between two adjacent laser spots in the laser's field of view is calculated as follows:

[0128]

[0129] In formula (9), N spot Indicates the minimum interval between two adjacent laser spots in the TX field of view, d baseline Indicates the baseline distance between the laser and the photoelectric sensor, Dist min Indicates the minimum detection distance of the photoelectric sensor, FOV h Indicates the lateral field of view of the photoelectric detection unit, N h Indicates the lateral resolution of the photodetection unit. The symbol for rounding up is the maximum offset corresponding to the minimum detection distance. In the embodiment of the present application, the maximum offset value is added by 1 to the result of the rounding up of this maximum offset, and the resulting value is used as the minimum spacing between two adjacent laser spots in the laser field of view. The minimum spacing is represented by the number of photoelectric detection units.

[0130] Step 1203: Determine the photoelectric detection unit to be polled corresponding to each laser spot in each pulse emission cycle according to the photoelectric detection unit without parallax and the minimum interval.

[0131] For example, N spot =4 means that 4 consecutive photoelectric detection units are used as the photoelectric detection units to be polled corresponding to a certain laser spot, and the following 4 consecutive photoelectric detection units are used as the photoelectric detection units to be polled corresponding to the adjacent laser spot. Figure 7 For example, the minimum interval is 4. In the figure, photoelectric detection units 701-704 are the photoelectric detection units to be polled corresponding to laser spot 001, and photoelectric detection units 705-708 are the photoelectric detection units to be polled corresponding to laser spot 002.

[0132] The minimum interval N calculated according to formula (9) spot To determine the N to be polled corresponding to a laser spot spot Each photoelectric detection unit will not detect more than one laser spot in a pulse emission cycle. This reduces the difficulty of determining the signal light, avoids missing signal light, and enhances the pertinence and accuracy of signal light detection.

[0133] Step 1204: Determine the time window corresponding to each photoelectric detection unit to be polled.

[0134] The implementation of this step is shown in formulas (7) to (8) and Figure 8 .

[0135] Step 1205: Control each photoelectric detection unit to be polled to turn on and off according to the time window polling.

[0136] To understand how this step is implemented, please refer to Figure 9 .

[0137] Step 1206: Generate a direct time-of-flight histogram corresponding to the current scanning angle according to the electrical signals provided by each photoelectric detection unit that is turned on during the pulse transmission period at the current scanning angle.

[0138] When the target object is projected by S laser beams (S is an integer greater than 1) during the current pulse emission cycle, S direct flight time histograms can be generated. The time corresponding to the maximum count value of each direct flight histogram is the flight time of the corresponding laser spot. For an example of a histogram, refer to Figure 10 .

[0139] Step 1207: Find the peak in the direct flight time histogram to determine the flight time corresponding to the laser spot at the current scanning angle.

[0140] Step 1208: According to the flight time and the corresponding relationship between the flight time and the distance, the distance information of the laser spot at the current scanning angle is obtained as the depth information of the laser spot.

[0141] The implementation of the above steps 1207 to 1208 has been described in the above embodiments and will not be repeated here. The calculation method for obtaining the laser spot depth information by the flight time is shown in formula (6).

[0142] In order to smoothly stitch the depth information of the laser spot at each scanning angle to form a complete super-resolution depth image containing the target object, the following steps can be used to determine the target photodetection unit where the super-resolution pixel that receives the laser beam reflected at the laser spot is located and the position of the super-resolution pixel in the target photodetection unit (i.e., the super-resolution position).

[0143] Step 1209: Obtain the offset corresponding to the distance information according to the correspondence between the offset and the distance.

[0144] Based on formula (3), the offset expression corresponding to the distance information of the laser spot at the current scanning angle can be obtained:

[0145]

[0146] In formula (10), d obj Indicates the distance information of a laser spot at the current scanning angle, σ obj Indicates the offset corresponding to the distance information.

[0147] The offset calculated according to formula (10) typically includes an integer part and a decimal part. The integer part indicates the number of photodetection units that the target photodetection unit is offset from the photodetection unit without parallax, where the target photodetection unit is the photodetection unit where the laser spot is located. The decimal part of the offset indicates the super-resolution position of the target photodetection unit where the laser spot is received.

[0148] σ obj =3.25 as an example, it means that the target photodetection unit is offset by 3 photodetection units relative to the photodetection unit without parallax. In order to accurately determine the super-resolution pixel on the target photodetection unit that receives the laser spot, the following steps 1210 need to be performed.

[0149] Step 1210: Determine the super-resolution pixel where the laser spot is detected in the target photodetection unit at the current scanning angle according to the offset and the super-resolution multiple of the photoelectric sensor, so as to construct a corresponding relationship between the depth information and the super-resolution pixel.

[0150] The following formula expresses how to determine the super-resolution pixel receiving the laser spot:

[0151]

[0152] In formula (11), l rx Indicates the ordinal number of the super-resolution pixel that detects the laser spot in the target photoelectric detection unit, N supres Represents the super-resolution multiple of the photoelectric sensor, σ obj Indicates the offset corresponding to the distance information of the laser spot. is the floor symbol, Is the rounding symbol. Figure 7 For example, a photodetection unit includes 4 super-resolution pixels in the horizontal direction, so the super-resolution factor is 4. rx The value ranges from 1 to N supres When N supres =4, then l rx =1, 2, 3, 4. obj =3.25 as an example, the ordinal number of the super-resolution pixel that detects the laser spot is calculated according to formula (11) to be 1, indicating that the super-resolution pixel receiving the laser spot is the first super-resolution pixel of the target photoelectric detection unit along the moving direction of the laser spot.

[0153] In this way, the correspondence between the first super-resolution pixel of the target photodetection unit along the moving direction of the laser spot and the depth information of the laser spot is constructed. In the scenario where laser pulses are emitted to the target object in a dot matrix projection manner, the correspondence between multiple super-resolution pixels and the depth information of the laser spot can be obtained for each scanning angle. It should be noted that steps 1201 to 1210 are performed in a loop. Therefore, by repeatedly executing steps 1201 to 1210, the correspondence between the laser spot depth information of each super-resolution pixel that has received the laser spot can be constructed.

[0154] Step 1211: After scanning the target object, the depth information of the laser spot at each scanning angle is spliced ​​together using the correspondence between the depth information and the super-resolution pixels.

[0155] by Figure 7 For example, the depth information of the laser spot 001 in the first super-resolution pixel of the photodetection unit 701 and the depth information of the second super-resolution pixel in the photodetection unit 701 are spliced ​​together according to the position association of the two super-resolution pixels, and so on.

[0156] In the above embodiment, the minimum interval is obtained in step 1202, and then the photoelectric detection unit to be polled corresponding to each laser spot within each pulse emission cycle is determined based on the minimum interval in step 1203. This reduces the difficulty of determining the signal light, avoids missed signal light detection, and enhances the targetedness and accuracy of signal light detection. The corresponding relationship between depth information and super-resolution pixels is established in step 1210, which improves the efficiency of stitching depth information at each position of each target object and increases the speed of depth imaging.

[0157] Based on the depth imaging method provided in the aforementioned embodiment, the present application also provides a depth imaging system, which is described below in conjunction with the embodiments and accompanying drawings.

[0158] System Example:

[0159] See also Figure 13 , which is a schematic diagram of the structure of the depth imaging system provided by the embodiment of the present application. Figure 13 As shown, the depth imaging system includes:

[0160] Laser 1301, controller 1302, gate switch 1303, photosensor 1304, time-to-digital converter TDC and processor 1305;

[0161] The controller 1302 is connected to the laser 1301. The controller 1302 is configured to control the laser 1301 to scan the target object at different scanning angles, and to emit laser pulses at a pulse emission cycle at each scanning angle.

[0162] In a possible implementation, the controller 1302 sets the pulse emission period of the laser 1301 , and the laser 1301 emits laser pulses at the pulse emission period according to a pulse control signal provided by the controller 1302 .

[0163] In another possible implementation, the controller 1302 may control the scanning angle of the laser 1301. When the controller 1302 transmits a scanning angle adjustment signal to the laser 1301, the laser 1301 adjusts the scanning angle according to the scanning angle adjustment signal.

[0164] The photoelectric sensor 1304 includes multiple photoelectric detection units, each of which is divided into multiple super-resolution pixels according to the size of the laser spot. The photoelectric detection unit can be a SPAD or an APD. The specific type of the photoelectric detection unit is not limited here. Figure 13 In the figure, only SPAD 1, SPAD 2, SPAD 3 ... SPAD N are used as examples to represent different photodetection units.

[0165] Gating switch 1303 connects all photodetection units of photoelectric sensor 1304. Gating switch 1303 is used to control the photodetection units on photoelectric sensor 1304 to turn on and off during each pulse transmission cycle. The enabled photodetection units receive the light signal reflected by the target object (i.e., the reflected laser beam) and convert the light signal into an electrical signal.

[0166] The controller 1302 and the processor 1305 are respectively connected to a time-to-digital converter TDC.

[0167] The time-to-digital converter (TDC) is also connected to the photodetection units of the photoelectric sensor 1304 via the selection switch 1303. The TDC is used to obtain the flight time based on the electrical signals (which also provide the time when the light signal was detected) provided by the photodetection units that are polled and turned on during the pulse transmission cycle and the emission time of each pulse at the current scanning angle, and convert the flight time into a count value.

[0168] Processor 1305 is used to form a direct flight time histogram corresponding to the current scanning angle based on the count value and electrical signal converted by the time-to-digital converter TDC; obtain the depth information of the laser spot at the current scanning angle based on the direct flight time histogram; after the laser 1301 completes scanning the target object, splice the depth information of the laser spot at each scanning angle to obtain a super-resolution depth image of the target object.

[0169] The above is the depth imaging system provided by the embodiment of the present application. Since the photodetection unit is turned on in a polling manner within each pulse emission cycle, the cumulative exposure time of the photodetection unit on the photoelectric sensor is greatly shortened compared to the time-sharing opening of the photodetection unit, thereby reducing power consumption and improving the frame rate and depth imaging speed. In addition, compared to the method of turning on all photodetection units at the same time, the polling opening method ensures that the photodetection unit turned on at a certain time is not interfered with by other adjacent photodetection units, and the converted signal has a higher signal-to-noise ratio, thereby ensuring a higher probability of detecting effective signals, which is beneficial to improving the imaging quality of the depth image of the target object.

[0170] In polling-on mode, the time window during which each photodetector unit is enabled within a pulse emission cycle is precisely controlled, accurately receiving photons that may return at various distances and minimizing interference from ambient light. Because the number of ambient light photons collected during the time when multiple photodetector units are enabled within a pulse emission cycle is equivalent to the number collected during the time when a single photodetector unit is continuously enabled in the prior art, and the detection of signal light is equivalent to fully enabling all photodetector units, there is no signal loss and system power consumption is significantly reduced.

[0171] Optionally, the depth imaging system may further include a memory connected to the processor and configured to store the direct time-of-flight histogram.

[0172] The present application embodiment provides an exemplary implementation of the above laser. Figure 14 , which shows the structure of a laser. Figure 14 As shown, the laser includes: a laser light source 13011, a collimating lens 13012, a deflecting mirror 13013, a spectrometer 13014 and a driving device 13015.

[0173] The laser light source 13011 is used to emit a laser beam, and the laser beam includes laser pulses emitted according to a pulse emission cycle;

[0174] The collimating lens 13012 is used to collimate the laser beam and send it to the deflection mirror;

[0175] The deflection mirror 13013 is connected to the driving device 13015 and is used to reflect the laser beam from the collimating lens 13012 to the beam splitter 13014. During this period, the deflection mirror 13013 is driven by the driving device 13015 to perform periodic deflection. The deflection mirror 13013 is mechanically and / or electrically connected to the driving device 13015.

[0176] The beam splitter 13014 is used to split the received laser beam into multiple beams and then project the multiple laser beams toward the target object. Depending on the design of the beam splitter 13014, the projected multiple laser beams may be parallel to each other or at an angle.

[0177] When the controller 1302 controls Figure 14 When the laser shown adjusts the scanning angle, it may specifically send a scanning angle adjustment signal to the driving device 13015, and then the driving device 13015 drives the deflection mirror 13013 to rotate according to the scanning angle adjustment signal.

[0178] It should be understood that in this application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "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, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0179] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A depth imaging method, characterized in that: include: Scanning the target object at different scanning angles, and emitting laser pulses at a pulse emission cycle at each scanning angle; Polling and controlling the opening and closing of a photoelectric detection unit on a photoelectric sensor in each pulse emission cycle; the photoelectric sensor includes a plurality of photoelectric detection units, each of which is divided into a plurality of super-resolution pixels according to the size of the laser spot; According to the electrical signals provided by each photoelectric detection unit that is turned on in a polling cycle during the pulse emission period, the depth information of the laser spot at the current scanning angle is obtained; After scanning the target object, the depth information of the laser spot at each scanning angle is spliced ​​to obtain a super-resolution depth image of the target object; The polling control of turning on and off the photoelectric detection unit on the photoelectric sensor in each pulse emission cycle specifically includes: Determining the photoelectric detection unit to be polled in each pulse emission cycle; Determining a time window corresponding to each of the photoelectric detection units to be polled; Controlling each of the photoelectric detection units to be polled to turn on and off according to the time window polling; The emitting of laser pulses at each scanning angle in a pulse emission cycle specifically includes: emitting laser pulses toward the target object in a dot matrix projection manner for a plurality of pulse emission cycles at each scanning angle, so as to simultaneously form a plurality of laser spots on the photoelectric sensor; The step of determining the photoelectric detection unit to be polled in each pulse emission cycle specifically includes: Obtain the minimum interval between two adjacent laser spots in the field of view of the laser; The photoelectric detection unit to be polled corresponding to each laser spot in each pulse emission cycle is determined according to the photoelectric detection unit without parallax and the minimum interval.

2. The depth imaging method according to claim 1, characterized in that The obtaining of the minimum interval between two adjacent laser spots in the field of view of the laser specifically includes: The minimum interval between two adjacent laser spots in the field of view of the laser is obtained according to the baseline distance between the laser and the photoelectric sensor, the minimum detection distance of the photoelectric sensor, the lateral field angle and the lateral resolution of the photoelectric detection unit.

3. The depth imaging method according to claim 1, wherein: Determining the time window corresponding to each of the photoelectric detection units to be polled specifically includes: determining an offset range of each of the photodetection units to be polled relative to the photodetection unit without parallax; Determining, according to the offset range and the correspondence between the offset and the distance, a distance range corresponding to when the laser spot falls on each of the photoelectric detection units to be polled; According to the distance range and the corresponding relationship between the distance and the time delay, the flight time range within which each photoelectric detection unit to be polled can receive the laser spot is determined; the flight time range serves as the time window.

4. The depth imaging method according to claim 1, wherein: The depth information of the laser spot at the current scanning angle is obtained according to the electrical signals provided by each photoelectric detection unit that is turned on by polling during the pulse emission period, specifically including: Generate a direct time-of-flight histogram corresponding to the current scanning angle according to the electrical signals provided by each photoelectric detection unit that is turned on during the pulse emission period at the current scanning angle; Finding a peak in the direct flight time histogram to determine the flight time corresponding to the laser spot at the current scanning angle; According to the flight time and the corresponding relationship between the flight time and the distance, the distance information of the laser spot at the current scanning angle is obtained as the depth information of the laser spot.

5. The depth imaging method according to claim 4, characterized in that: After obtaining the distance information of the laser spot at the current scanning angle as the depth information of the laser spot, the method further includes: An offset corresponding to the distance information is obtained according to a correspondence between the offset and the distance; the integer part of the offset indicates the number of photoelectric detection units that the target photoelectric detection unit is offset from the photoelectric detection unit without parallax, the target photoelectric detection unit being the photoelectric detection unit where the laser spot is located, and the decimal part of the offset indicates the super-resolution position of the target photoelectric detection unit where the laser spot is received; Determining, based on the offset and the super-resolution multiple of the photoelectric sensor, the super-resolution pixel at which the laser spot is detected in the target photoelectric detection unit at the current scanning angle, so as to establish a corresponding relationship between the depth information and the super-resolution pixel; After scanning the target object, stitching the depth information of the laser spot at each scanning angle specifically includes: After the target object is scanned, the depth information of the laser spot at each scanning angle is spliced ​​together using the correspondence between the depth information and the super-resolution pixels.

6. The depth imaging method according to claim 1, characterized in that: Scanning the target object at different scanning angles specifically includes: Before scanning the target object at a next scanning angle, the laser light path is adjusted to form the next scanning angle.

7. A depth imaging system, characterized in that: include: Lasers, controllers, gate switches, photoelectric sensors, time-to-digital converters, and processors; The controller is connected to the laser; the photoelectric sensor includes a plurality of photoelectric detection units, each of which is divided into a plurality of super-resolution pixels according to the size of the laser spot; the gate switch is connected to all the photoelectric detection units of the photoelectric sensor; the controller and the processor are respectively connected to the time-to-digital converter; the time-to-digital converter is also connected to the photoelectric detection units through the gate switch; The controller is used to control the laser to scan the target object at different scanning angles, and emit laser pulses at a pulse emission cycle at each scanning angle; The gate switch is used to poll and control the photoelectric detection unit on the photoelectric sensor to turn on and off in each pulse emission cycle; the turned-on photoelectric detection unit is used to receive the light signal reflected by the target object and convert the light signal into an electrical signal; The time-to-digital converter is used to obtain the flight time based on the electrical signals provided by each photoelectric detection unit that is polled and turned on during the pulse emission period and the emission time of each pulse at the current scanning angle, and convert the flight time into a count value; The processor is configured to form a direct time-of-flight histogram corresponding to a current scanning angle based on the count value converted by the time-to-digital converter and the electrical signal; obtain depth information of the laser spot at the current scanning angle based on the direct time-of-flight histogram; and after the laser completes scanning the target object, splice the depth information of the laser spot at each scanning angle to obtain a super-resolution depth image of the target object; The strobe switch is specifically used for: Determining the photoelectric detection unit to be polled in each pulse emission cycle; Determining a time window corresponding to each of the photoelectric detection units to be polled; Controlling each of the photoelectric detection units to be polled to turn on and off according to the time window polling; The controller is specifically used for: emitting laser pulses toward the target object in a dot matrix projection manner for a plurality of pulse emission cycles at each scanning angle, so as to simultaneously form a plurality of laser spots on the photoelectric sensor; When determining the photoelectric detection unit to be polled in each pulse emission cycle, the gating switch is specifically used to: Obtain the minimum interval between two adjacent laser spots in the field of view of the laser; The photoelectric detection unit to be polled corresponding to each laser spot in each pulse emission cycle is determined according to the photoelectric detection unit without parallax and the minimum interval.

8. The depth imaging system according to claim 7, characterized in that The laser comprises: a laser light source, a collimating lens, a deflecting mirror, a beam splitting element and a driving device; The laser light source is used to emit a laser beam, and the laser beam includes laser pulses emitted according to a pulse emission period; The collimating lens is used to collimate the laser beam and send it to the deflecting mirror; The deflection mirror is connected to the driving device and is used to reflect the laser beam from the collimating lens to the beam splitting element; during this period, the deflection mirror is driven by the driving device to perform periodic deflection; The beam splitting element is used to split the received laser beam into multiple beams and then project the multiple laser beams toward the target object.

Images