A single-photon lidar imaging detection system

Abstract

The invention discloses a single-photon laser radar imaging detection system, comprising: a laser emission subsystem, a laser receiving subsystem, and a timing control and data processing subsystem; the laser emission subsystem is used to realize pulse laser emission and output a light synchronization signal at the same time; the timing control and data processing subsystem is used to receive the light synchronization signal output by the laser emission subsystem, and output a trigger signal for the laser receiving subsystem, and process the detection data output by the laser receiving subsystem at the same time; the laser receiving subsystem receives signals according to a preset frequency or based on the trigger signal output by the timing control and data processing subsystem; the photon laser radar imaging detection system performs imaging detection in a fast scanning working mode or an adaptive distance gating working mode. The fast scanning is combined with the adaptive distance gating to improve the spatial scanning efficiency of the system, and make up for the shortcomings of the existing Geiger focal plane detector, such as long dead time and low detection efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of radar imaging detection, and particularly relates to a single-photon lidar imaging detection system. Background Art

[0002] A single-photon detector (SPD) is a highly sensitive optoelectronic detector that can respond to photon-level signals and is the basis for fields such as single-photon radar detection and quantum communication. With the continuous development of basic software and hardware technologies, the three-dimensional imaging detection technology of single-photon lidar based on Geiger focal plane cameras has attracted more and more attention, and many research results have been introduced, with significant improvements in aspects such as operating range and imaging effect, and having high application value.

[0003] Existing single-photon detectors have a relatively long dead time, which severely limits their detection efficiency. Taking a single-photon lidar with a detection range of 0 - 150 km as an example, within 1 ms after the system emits a laser pulse signal, the laser echo signal reflected by the target may arrive at any time. This requires the single-photon detector to be in a standby state at all times during this 1 ms period. However, a Geiger focal plane camera operates in a gated state and has a relatively long detector dead time, making it impossible to detect the photon echo signal reflected by the target in real time. Taking an existing Geiger focal plane camera as an example, its maximum operating frequency is 25 kHz, and the longest effective detection time is 4 us. That is, within the shortest frame period of 40 us, only 1 / 10 of the time can receive signals normally, and the rest of the time is dead time and cannot receive photon echo signals. Therefore, it cannot meet the aforementioned requirement of being in a real-time standby state within 1 ms.

[0004] To solve the above contradiction, it is urgent to design a new single-photon lidar imaging detection system. Summary of the Invention

[0005] The purpose of the present invention is to disclose a new single-photon lidar imaging detection system to overcome the problems of the prior art. By combining fast scanning with adaptive range gating, the spatial scanning efficiency of the system is improved, and the deficiencies of the existing Geiger focal plane detector with a long dead time and low detection efficiency are made up for.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A single-photon lidar imaging detection system, the single-photon lidar imaging detection system comprising: a laser emission subsystem, a laser reception subsystem, and a timing control and data processing subsystem; wherein, the laser emission subsystem is used to implement pulsed laser emission and simultaneously output an optical output synchronization signal; the timing control and data processing subsystem is used to receive the optical output synchronization signal output by the laser emission subsystem, output a trigger signal to the laser reception subsystem, and simultaneously process the detection data output by the laser reception subsystem; the laser reception subsystem receives signals according to a preset frequency or based on the trigger signal output by the timing control and data processing subsystem; the photon lidar imaging detection system performs imaging detection in a fast scanning operating mode or an adaptive range gating operating mode.

[0008] According to a preferred embodiment, when the photon lidar imaging detection system performs imaging detection in the fast scanning operating mode, it proceeds as follows:

[0009] S1: The laser emission module emits a single laser pulse and simultaneously outputs an optical output synchronization signal to the timing control and data processing subsystem as the starting point for pulse flight time measurement.

[0010] S2: After the timing control and data processing subsystem receives the rising edge of the optical output synchronization signal, it actively delays by a preset pulse phase d x , and then outputs n periodic pulse trains to the laser reception subsystem as the external trigger signal for the detector in the laser reception subsystem. Under the action of the n external trigger pulses, the detector completes n detection cycles, outputs n frames of detection data, and inputs the data into the timing control and data processing subsystem for target detection.

[0011] S3: Change the pulse phase d x , perform m kinds of delay loop traversals from d 1 to d m to complete a full scan of the space to be measured.

[0012] S4: Send the detection data into the timing control and data processing subsystem for target detection, and invert the target distance and target three-dimensional imaging from the detection results.

[0013] According to a preferred embodiment, the value of m is: m = T f / T w , where T f is the measurement period of the detector in the laser reception subsystem, and T w is the effective working time in the measurement period of the detector in the laser reception subsystem.

[0014] According to a preferred embodiment, the calculation method of the pulse phase d x is:

[0015] d x = D + (x - 1)T w ; x = 1, 2, … m

[0016] D is the inherent time delay, determined by the minimum distance L between the space to be detected and the system, and the calculation method is: min Decide, the calculation method is:

[0017]

[0018] Among them, c represents the speed of light. By increasing the delay d x Incremental method to achieve scanning of the target area from near to far.

[0019] According to a preferred embodiment, the pulse phase d x The calculation method is:

[0020] d x = D + (m - x)T w ; x = 1, 2, … m

[0021] D is the inherent time delay, determined by the minimum distance L between the space to be detected and the system, and the calculation method is: min Decide, the calculation method is:

[0022]

[0023] Among them, c represents the speed of light. By decreasing the delay d x Decremental method to achieve scanning of the target area from far to near.

[0024] According to a preferred embodiment, when the photon laser radar imaging detection system is in the fast scanning working mode, the number of measurements corresponding to each pulse phase d x Is N, and N is a positive integer constant.

[0025] According to a preferred embodiment, when the photon laser radar imaging detection system performs imaging detection in the adaptive distance gating working mode, the following steps are carried out:

[0026] When the photon laser radar imaging detection system scans the entire space to be measured in the fast scanning working mode, when no target is detected during the change of the pulse phase d x During the process, when no target is detected, the m - type delay loop traversal from d1 to dm is completed until the complete scanning of the space to be measured is completed;

[0027] When at the pulse phase d xIf a target is detected during the change process, then according to the detected target distance, update the delay pulse phase of the next measurement cycle to P, so that when the photon echo signal reflected by the target arrives, the detector in the laser receiving subsystem is in an effective working state;

[0028] When in the tracking and detection process, if the target is not detected continuously for more than k times, where k is a preset value, it means the target is lost. Then the system enters the fast scanning working mode, traverses the airspace to be detected again until the target is detected again, and then the system switches to the adaptive distance gating working mode.

[0029] The main solution of the present invention and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and claimed by the present invention. Those skilled in the art can understand that there are various combinations according to the prior art and common general knowledge after understanding the solution of the present invention. All of them are the technical solutions to be protected by the present invention and will not be enumerated here.

[0030] The beneficial effects of the present invention: The single-photon laser radar imaging detection system of the present invention utilizes the advantage of the high frame rate of the single-photon detector, and through strict timing coordination, makes up for the deficiency of the relatively long dead time of the detector, effectively improving the detection efficiency of the system. And by combining the fast scanning mode and the adaptive distance gating mode, it can effectively adapt to the detection of high-speed moving targets in the air. Description of the Drawings

[0031] Figure 1 is a schematic structural diagram of the single-photon laser radar imaging detection system of the present invention;

[0032] Figure 2 is a schematic diagram of the fast scanning timing relationship of the single-photon laser radar imaging detection system of the present invention. Detailed Embodiments

[0033] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0034] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Additionally, the present invention points out that in the present invention, if the specific structures, connection relationships, positional relationships, power source relationships, etc. involved are not specifically written out, the structures, connection relationships, positional relationships, power source relationships, etc. involved in the present invention are those that can be known by those skilled in the art on the basis of the prior art without creative labor.

[0035] Embodiment 1:

[0036] Reference Figure 1 As shown in the figure, a single-photon lidar imaging detection system is shown. The single-photon lidar imaging detection system includes: a laser emission subsystem, a laser reception subsystem, and a timing control and data processing subsystem. The photon lidar imaging detection system can be divided into two working modes: the first is the fast scanning working mode, and the second is the adaptive range gating mode.

[0037] Among them, the laser emission subsystem is used to realize pulsed laser emission and simultaneously output an optical output synchronization signal; the timing control and data processing subsystem is used to receive the optical output synchronization signal output by the laser emission subsystem, output a trigger signal for the laser reception subsystem, and simultaneously process the detection data output by the laser reception subsystem; the laser reception subsystem receives signals according to a preset frequency or based on the trigger signal output by the timing control and data processing subsystem.

[0038] Fast scanning working mode

[0039] Reference Figure 2 As shown in the figure, the fast scanning working mode mainly performs fast scanning and traversal of the detection area Td under the condition of unknown target distance. The detection area Td here represents the time range when the reflected laser pulses of the target at a certain distance arrive. For example, assuming that the system wants to detect targets at a distance of 15 km to 150 km, the arrival time range of the reflected laser pulse echoes is 0.1 ms to 1 ms, and the corresponding detection area Td is 0.9 ms. Here, the minimum detection distance of the system is denoted as Lmin, and the maximum detection distance is denoted as Lmax.

[0040] When the photon lidar imaging detection system performs imaging detection in the fast scanning working mode, it proceeds as follows:

[0041] S1: The laser emission module emits a laser pulse once and simultaneously outputs an optical output synchronization signal to the timing control and data processing subsystem as the starting point for pulse flight time measurement.

[0042] S2: After the rising edge of the light emission synchronization signal is received by the timing control and data processing subsystem, it actively delays the preset pulse phase d x , and then outputs n periodic pulse trains to the laser receiving subsystem as the external trigger signal for the detector in the laser receiving subsystem. Under the action of n external trigger pulses, the detector completes n detection cycles, outputs n frames of detection data, and inputs the data into the timing control and data processing subsystem for target detection. By adopting a 1:n timing control scheme, when the laser emits one laser pulse, the detector works n times, greatly improving the system scanning efficiency.

[0043] After the laser receiving subsystem receives the external trigger pulse signal, the Geiger focal plane detector starts to enter the effective working state and responds to the received optical signal. The continuous effective working time length of the detector is T w , and the rest of the time is the dead time when the detector cannot respond to the optical signal. Among them, T w is determined by the detector itself, and the effective working time length is generally much smaller than the detection cycle T f . As Figure 2 shown, for the convenience of expression, it is assumed here that the high-level width of each trigger pulse represents the effective working time of the detector. (In practice, there may not be an actual corresponding relationship between the effective working time of the detector and the trigger level width. This is just an image expression method here)

[0044] S3: Change the pulse phase d x , and perform m kinds of delay loop traversals from d 1 ~d m to complete a complete scan of the space to be measured.

[0045] S4: Send the detection data into the timing control and data processing subsystem for target detection, and invert the target distance and target three-dimensional imaging from the detection results. The target distance is calculated based on the flight time of the laser pulse.

[0046] As Figure 2 shown, d x represents the delay of the external trigger signal. There are m kinds of delays in total, corresponding to m kinds of detection phases. When the system traverses all the phases, a scan of the detector area can be realized.

[0047] The value of m is: m = T f / T w , where T f is the measurement cycle of the detector in the laser receiving subsystem, and T w is the effective working time in the measurement cycle of the detector in the laser receiving subsystem.

[0048] Preferably, the calculation method of the pulse phase d x can be:

[0049] d x = D + (x - 1)T w ; x = 1, 2, … m

[0050] D is the inherent time delay, determined by the minimum distance L between the space to be detected and the system, and the calculation method is: min decided, and the calculation method is:

[0051]

[0052] where c represents the speed of light, and by increasing the delay d x incrementally, the target area is scanned from near to far.

[0053] Preferably, the pulse phase d x can also be calculated as:

[0054] d x = D + (m - x)T w ; x = 1, 2, … m

[0055] D is the inherent time delay, determined by the minimum distance L between the space to be detected and the system, and the calculation method is: min decided, and the calculation method is:

[0056]

[0057] where c represents the speed of light, and by decreasing the delay d x decrementally, the target area is scanned from far to near.

[0058] The above two calculation methods of the pulse phase d x are only typical processing methods. The specific method can be relatively flexible, as long as m delay values can be traversed. Here, they are not listed one by one. This patent aims to protect the time sequence splicing achieved by this traversal phase method. The specific changes in the traversal method are only special cases of this splicing scheme and should all fall within the protection scope of the patent.

[0059] Preferably, when the photon laser radar imaging detection system operates in the fast scanning working mode, the number of measurement times corresponding to each pulse phase d x is N, and N is a positive integer constant. By performing multiple detections at each pulse phase d x the measurement accuracy of the detection system is ensured.

[0060] Adaptive distance gating working mode

[0061] The basic timing control process of the adaptive distance gating working mode is the same as that of the fast scanning working mode, and the main difference lies in the different ways of obtaining dx.

[0062] When the photon laser radar imaging detection system performs imaging detection in the adaptive distance gating working mode, it proceeds as follows:

[0063] When the photon laser radar imaging detection system scans the entire space to be measured in the fast scanning working mode, during the change of the pulse phase d x If no target is detected during the change process, then the m - type delay loop traversal from d1 to dm is completed until the complete scanning of the space to be measured is finished;

[0064] When a target is detected during the change of the pulse phase d x If a target is detected during the change process, then according to the detected target distance, the delay pulse phase of the next measurement cycle is updated to P, so that when the photon echo signal reflected by the target arrives, the detector in the laser receiving subsystem is in an effective working state. Thus, it is ensured that each laser pulse reflected by the target can be effectively received, and adaptive distance gating tracking detection is achieved.

[0065] When, during the tracking detection process, the target is not detected continuously for more than k times (k is a preset value), it means the target is lost. Then the system enters the fast scanning working mode and traverses the airspace to be detected again until the target is detected again, and the system then switches to the adaptive distance gating working mode.

[0066] The single - photon laser radar imaging detection system of the present invention utilizes the advantage of the high frame rate of the single - photon detector. Through strict timing coordination, it makes up for the deficiency of the relatively long dead time of the detector and effectively improves the detection efficiency of the system. And by combining the fast scanning mode and the adaptive distance gating mode, it can effectively adapt to the detection of high - speed moving targets in the air.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A single-photon lidar imaging detection system, characterized in that, the single-photon lidar imaging detection system comprises: a laser emission subsystem, a laser reception subsystem, and a timing control and data processing subsystem; wherein, the laser emission subsystem is used to implement pulsed laser emission and simultaneously output an optical output synchronization signal; the timing control and data processing subsystem is used to receive the optical output synchronization signal output by the laser emission subsystem, output a trigger signal to the laser reception subsystem, and simultaneously process the detection data output by the laser reception subsystem; the laser reception subsystem receives signals according to a preset frequency or based on the trigger signal output by the timing control and data processing subsystem; the single-photon lidar imaging detection system performs imaging detection in a fast scanning working mode or an adaptive range gating working mode; when the single-photon lidar imaging detection system performs imaging detection in the fast scanning working mode, it proceeds according to the following steps: S1: The laser emission module emits a laser pulse once and simultaneously outputs an optical output synchronization signal to the timing control and data processing subsystem as the starting point for pulse flight time measurement; S2: After the rising edge of the light output synchronization signal is received by the timing control and data processing subsystem, it actively delays the preset pulse phase , and then outputs n periodic pulse trains to the laser receiving subsystem as the external trigger signal for the detectors in the laser receiving subsystem. Under the action of the n external trigger pulses, the detectors complete n detection cycles, output n frames of detection data, and input the data into the timing control and data processing subsystem for target detection; S3: Change the pulse phase , perform m kinds of delay loop traversals starting from to complete a full scan of the space to be measured; The value of m is: m = T f / T w , where T f is the measurement period of the detector in the laser receiving subsystem, and T w is the effective working time in the measurement period of the detector in the laser receiving subsystem; S4: The detection data is sent into the timing control and data processing subsystem for target detection, and the target distance and target three-dimensional imaging are retrieved from the detection results; when the single-photon lidar imaging detection system performs imaging detection in the adaptive range gating working mode, it proceeds according to the following steps: When the single-photon lidar imaging detection system scans the entire space to be measured in the fast-scanning working mode, during the process of changing the pulse phase when no target is detected, m kinds of delay cycles from d1 to dm are completed until the complete scanning of the space to be measured is finished; When a target is detected during the pulse phase change, the delay pulse phase of the next measurement cycle is updated to P according to the detected target distance, so that when the photon echo signal reflected by the target arrives, the detector in the laser receiving subsystem is in an effective working state; During the tracking detection process, if the target is not detected continuously more than k times, where k is a preset value, it indicates that the target is lost. The system then enters the fast scanning working mode and traverses the area to be detected again until the target is detected again, and the system switches back to the adaptive range gating working mode.

2. The single-photon lidar imaging detection system according to claim 1, characterized in that, Pulse phase is calculated as follows: D is the proper time delay, which is determined by the minimum distance L between the system and the space to be detected, and the calculation method is as follows: min determined by, and the calculation method is: Among them, c represents the speed of light, and through the way of increasing the delay The scanning of the target area from near to far is realized.

3. The single-photon lidar imaging detection system according to claim 1, characterized in that, Pulse phase is calculated as follows: D is the proper time delay, which is determined by the minimum distance L between the system and the space to be detected, and the calculation method is as follows: min Determined, the calculation method is: Among them, c represents the speed of light, and through the way of decreasing the delay, the scanning of the target area from far to near is realized.

4. The single-photon lidar imaging detection system according to claim 1, characterized in that, When the single-photon lidar imaging detection system operates in the fast-scanning mode, the number of measurements corresponding to each pulse phase is N, where N is a positive integer constant.

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