A single-photon laser non-scanning imaging detection system for moving targets

Abstract

The present invention discloses a single-photon laser non-scanning imaging detection system for moving targets. The system comprises a laser emission module, a laser ranging receiver module, a ranging signal processing module, a laser imaging receiver module, an imaging signal processing module, and a timing control module. The present invention integrates the design of laser emission, laser ranging, and laser imaging. By using ranging to guide imaging, the imaging detector only needs to operate within a very short period of time, thereby improving the detection efficiency and three-dimensional imaging quality of the single-photon three-dimensional imaging detection system. Furthermore, the operating modes of the laser emission module are optimized, and through the coordinated operation of multiple modes, the laser simultaneously meets the requirements of high pulse energy and high pulse repetition rate for photon imaging detection, adapting to different mission requirements, reducing design costs, and improving operational reliability.

Description

Technical Field

[0001] The invention relates to a moving target single-photon laser non-scanning imaging detection system, belonging to the technical field of radar imaging. Background Art

[0002] A single-photon detector (SPD) is a highly sensitive photoelectric detector that can respond to photon-level signals and is the basis of single-photon radar detection, quantum communication and other fields.

[0003] In the existing technology, single-photon laser non-scanning three-dimensional imaging detection uses a Geiger focal plane detector to obtain a large amount of laser point cloud information at one time through flash imaging. It has the advantages of high imaging angular resolution, long effective range, simple structure, and fast imaging speed. It can quickly obtain the long-range three-dimensional contour features of the target and provide support for target identification. It is an important development direction of future lidar detection systems.

[0004] The inventors have found that there are at least the following problems in the existing technology: single-photon laser non-scanning imaging detection faces two problems: first, the Geiger focal plane detector is easily interfered by background noise when working for a long time, resulting in a short effective working time and inability to be in standby state in real time. It is difficult to achieve efficient reception of target echo signals under the premise of unknown target distance; second, the Geiger focal plane detector adopts a time-correlated photon counting detection working mode, which requires multi-frame accumulation of detection results, requiring the system to achieve multiple repeated detection of the target in a relatively short time. When the laser pulse repetition rate is low, the time correlation between adjacent multi-frame detection results decreases, which seriously affects the three-dimensional imaging quality of the target. High-energy pulse lasers generally cannot achieve high repetition rates, and place high requirements on the laser. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a moving target single-photon laser non-scanning imaging detection system.

[0006] The present invention is achieved through the following technical solutions.

[0007] The present invention provides a moving target single-photon laser non-scanning imaging detection system, comprising a laser emission module, a laser ranging receiving module, a ranging signal processing module, a timing control module, a laser imaging receiving module, and an imaging signal processing module, wherein:

[0008] The laser emission module emits narrow pulse lasers toward the target and outputs optical synchronization signals through the laser;

[0009] The laser ranging receiving module receives the laser echo pulse reflected by the target, performs optoelectronic conversion through an internal single-photon ranging detector, and outputs a photon counting pulse signal;

[0010] The ranging signal processing module receives the light output synchronization signal output by the laser and the photon counting pulse signal output by the laser ranging receiving module, and outputs the target distance and the target distance-time function through a single-photon ranging algorithm based on multi-channel time correlation;

[0011] The timing control module receives the light output synchronization signal output by the laser and the distance-time function output by the ranging signal processing module, and outputs an external trigger signal through timing control logic;

[0012] The laser imaging receiving module receives the laser echo pulse reflected by the target and outputs imaging detection data through an internal single-photon imaging detector;

[0013] The imaging signal processing module receives the imaging detection data output by the laser imaging receiving module and outputs a three-dimensional image of the target.

[0014] The single-photon ranging detector is a free-running mode or quasi-continuous mode single-photon detector.

[0015] The single-photon imaging detector is a Geiger focal plane detector, and the detector operates in a gated mode.

[0016] The laser emitting module emits periodic narrow pulses to the target, including two working modes: a low-frequency working mode and a composite working mode.

[0017] The low-frequency working mode is: emitting laser pulses to the target at a fixed frequency; the composite working mode is: divided into three stages in one working cycle, a low pulse repetition frequency (PRF) pulse emission stage, a high PRF pulse emission stage, and a rest stage, and the stages alternate and cycle in sequence.

[0018] In the low PRF emission stage, the laser pulse PRF is f1, in the high PRF emission stage, the pulse PRF is f2, and f1 << f2, and no laser is emitted in the rest stage.

[0019] The system includes two task states: the system ranging task state and the system imaging task state. In the system ranging task state, the laser emitting module operates in the low-frequency working mode, and the system only completes the ranging function of the target; in the system imaging task state, the laser emitting module operates in the composite working mode, and the system completes the imaging detection function of the target.

[0020] The working method of the system ranging task state is:

[0021] (1) The laser emitting module operates in the low-frequency working mode, sends narrow pulse laser with a fixed pulse frequency to the target, and outputs a light output synchronization signal;

[0022] (2) The laser ranging receiver module receives the laser echo pulse reflected by the target and converts it into a photon counting pulse signal through the internal single photon ranging detector;

[0023] (3) The ranging signal processing module receives the photon counting signal output by the laser ranging receiving module, extracts the target echo arrival time from the counting pulse signal through the single photon ranging algorithm based on multi-path time correlation, and calculates the time difference Δt between the optical synchronization signal and the target echo arrival time. Calculate the target distance d.

[0024] The working method of the imaging task state is:

[0025] (1) The laser transmitting module operates in the low repetition rate transmitting stage of the composite working mode, and cooperates with the laser ranging receiving module and the ranging signal processing module to complete the ranging of the target. Its working method is the same as the ranging task state described in claim 8;

[0026] (2) After completing the distance measurement of the target during the low repetition rate laser emission phase, the target distance-time function is extracted from the distance measurement result by the least squares method, and the distance-time function is output to the timing control module;

[0027] (3) During the laser high repetition rate emission phase, the timing control module receives the target distance-time function and calculates the current target distance based on the target distance-time function;

[0028] (4) After receiving the laser light synchronization signal, the timing control module and the ranging signal processing module output an external trigger signal to the laser imaging receiving module after a delay according to the current distance;

[0029] (5) After receiving the external trigger signal, the laser imaging receiving module works for a fixed time slot and outputs a frame of imaging detection data;

[0030] (6) The imaging signal processing module receives the imaging detection data output by the laser imaging receiving module and outputs the target three-dimensional imaging through a single-photon three-dimensional reconstruction algorithm based on multi-frame time correlation;

[0031] (7) During the laser rest phase, the system does not perform any processing.

[0032] The beneficial effects of the present invention are as follows: by utilizing a design mode combining ranging and imaging, the target distance is acquired in advance through a long-range single-photon ranging system, thereby solving the problem that the effective working time of the Geiger focal plane detector is short and it is difficult to achieve efficient reception of the target echo signal under the premise of unknown target distance; by optimizing the design of the laser working mode, low-repetition-rate high-energy laser pulses are combined with the laser group pulse mode, so that rapid and repeated detection of the target is achieved in a short time, thereby improving the quality of imaging detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a working principle diagram of the system of the present invention;

[0034] Figure 2 This is an example diagram of the working timing of the low-frequency working mode of the present invention;

[0035] Figure 3 This is an example diagram of the working timing of the composite working mode of the present invention;

[0036] Figure 4 This is a timing diagram of the ranging guidance imaging reception work of the system of the present invention. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention through specific examples. 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 embodiments. The 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 the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0038] It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures. In addition, the present invention should point out that, in the present invention, if the specific structure, connection relationship, position relationship, power source relationship, etc. are not specifically written out, the structure, connection relationship, position relationship, power source relationship, etc. involved in the present invention are all known to those skilled in the art based on the existing technology without creative work.

[0039] like Figure 1 As shown, a single-photon laser non-scanning imaging detection system for moving targets consists of a laser emission module, a laser ranging receiving module, a ranging signal processing module, a timing control module, a laser imaging receiving module, and an imaging signal processing module, wherein:

[0040] (1) Laser emission module: The laser emission module emits narrow pulsed laser towards the target and outputs an optical output synchronization signal.

[0041] (2) Laser ranging receiving module: It receives the laser echo pulse reflected by the target, performs photoelectric conversion through an internal single-photon ranging detector, and outputs a photon counting pulse signal. Among them, the single-photon ranging detector operates in a free-running mode or a quasi-continuous mode.

[0042] (3) Ranging signal processing module: It receives the optical output synchronization signal output by the laser, receives the photon counting pulse signal output by the ranging receiving module, and after a single-photon ranging algorithm based on multi-channel time correlation, outputs the target distance. And through the distance data, using the least squares method, extracts the target distance-time function and outputs the function to the timing control module.

[0043] (4) Timing control module: It receives the optical output synchronization signal output by the laser, receives the distance-time function output by the ranging signal processing module, calculates the current target distance through the distance-time function, and outputs an external trigger signal according to the target distance and the timing control logic.

[0044] (5) Laser imaging receiving module: Under the action of the external trigger signal, it receives the laser echo pulse reflected by the target and outputs imaging detection data through an internal single-photon imaging detector.

[0045] (6) Imaging signal processing module: It receives the imaging detection data output by the imaging receiving module and outputs the three-dimensional imaging of the target through a single-photon three-dimensional reconstruction algorithm based on multi-frame time correlation.

[0046] The single-photon ranging detector is a free-running mode or quasi-continuous mode single-photon detector, and the single-photon imaging detector is a Geiger focal plane detector. The detector operates in a gated mode and can achieve non-scanning imaging of the target.

[0047] The laser emission module emits periodic narrow pulses towards the target, and its operation includes two working modes: low-frequency working mode and composite working mode:

[0048] (1) Low-frequency working mode: The low-frequency working mode emits laser pulses towards the target at a fixed frequency. An example of the working timing of the low-frequency working mode is as Figure 2 shown;

[0049] (2) Composite working mode: The composite working mode can be divided into three stages in one working cycle: low pulse repetition frequency pulse emission stage, high pulse repetition frequency pulse emission stage, and rest stage. Each stage works alternately in a cycle. In the low pulse repetition frequency emission stage, the laser pulse repetition frequency is f1, and in the high pulse repetition frequency emission stage, the pulse repetition frequency is f2, where f1 << f2. No laser is emitted in the rest stage. An example of the working timing of the composite working mode is as Figure 3 shown.

[0050] The system working method includes two task states: system ranging task state and system imaging task state.

[0051] In the system ranging task state, the laser emission module works in low-frequency working mode, and the system only completes the ranging function of the target. Its basic working process is as follows:

[0052] (1) The laser emission module works in low-frequency working mode, sends narrow pulse laser with fixed pulse frequency to the target, and outputs optical synchronization signal;

[0053] (2) The laser ranging receiver module receives the laser echo pulse reflected by the target and converts it into a photon counting pulse signal through the internal single photon ranging detector;

[0054] (3) The ranging signal processing module receives the photon counting signal output by the laser ranging receiving module, extracts the target echo arrival time from the counting pulse signal through the single photon ranging algorithm based on multi-path time correlation, and calculates the time difference Δt between the optical synchronization signal and the target echo arrival time. Calculate the target distance.

[0055] In the imaging task state of the system, the laser emission module works in a composite working mode, and the system completes the imaging detection function of the target. Among them, the system realizes the distance measurement of the target in the low repetition rate emission stage of the laser, and relies on the ranging results to guide the system to quickly image the target in the high repetition rate emission stage of the laser. The timing relationship of the system ranging guidance imaging reception work is as follows: Figure 4 shown.

[0056] In the imaging task state of the system, the laser emission module works in the composite working mode, and the system completes the imaging detection function of the target. The workflow of the imaging task state is as follows:

[0057] (1) In the low repetition rate emission phase of the composite working mode, the laser cooperates with the laser ranging receiving module and the ranging signal processing module to complete the ranging of the target. Its working method is the same as that in the ranging task state;

[0058] (2) After completing the distance measurement of the target in the low repetition rate emission phase of the laser, the distance-time function of the target distance is extracted from the distance measurement result by the least squares method, and the distance-time function is output to the timing control module;

[0059] (3) During the laser high repetition rate emission phase, the timing control module receives the distance-time function and calculates the current target distance based on the distance-time function;

[0060] (4) After receiving the laser light synchronization signal, the timing control and signal processing module outputs an external trigger signal to the laser imaging receiving module after a delay according to the current distance;

[0061] (5) After receiving the external trigger signal, the laser imaging receiving module works for a fixed time and outputs a frame of imaging detection data;

[0062] (6) The imaging signal processing module receives the imaging detection data output by the laser imaging receiving module and outputs the target three-dimensional imaging through a single-photon three-dimensional reconstruction algorithm based on multi-frame time correlation;

[0063] (7) During the laser rest phase, the system does not perform any processing and waits for the laser to return to the standby state.

[0064] In summary, the present invention jointly designs laser emission, laser ranging, laser imaging, etc., and through ranging-guided imaging, the imaging detector only needs to work in a very short period of time, thereby improving the detection efficiency and three-dimensional imaging quality of the single-photon three-dimensional imaging detection system; the working mode of the laser emission module is optimized and designed, and through the coordinated operation of multiple modes, the laser can simultaneously meet the requirements of high pulse energy and high pulse repetition rate of photon imaging detection, adapt to different task needs, reduce design costs, and improve work reliability.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A moving target single-photon laser non-scanning imaging detection system, characterized by: It includes a laser emission module, a laser ranging receiving module, a ranging signal processing module, a timing control module, a laser imaging receiving module, and an imaging signal processing module, where: The laser emission module emits narrow pulsed laser towards the target and outputs an optical emission synchronization signal through the laser. The laser ranging receiving module receives the laser echo pulse reflected by the target, performs photoelectric conversion through the internal single-photon ranging detector, and outputs a photon counting pulse signal. The ranging signal processing module receives the optical emission synchronization signal output by the laser and the photon counting pulse signal output by the laser ranging receiving module, and outputs the target distance and the target distance-time function through the single-photon ranging algorithm based on multi-channel time correlation. The timing control module receives the optical emission synchronization signal output by the laser and the distance-time function output by the ranging signal processing module, and outputs an external trigger signal through the timing control logic. The laser imaging receiving module receives the laser echo pulse reflected by the target under the action of the external trigger signal, and outputs imaging detection data through the internal single-photon imaging detector. The imaging signal processing module receives the imaging detection data output by the laser imaging receiving module and outputs the three-dimensional imaging of the target. The laser emission module emits periodic narrow pulses towards the target, including two working modes: a low-frequency working mode and a composite working mode. The low-frequency working mode is to emit laser pulses towards the target at a fixed frequency; the composite working mode is divided into three stages in one working cycle: a low pulse repetition frequency (PRF) pulse emission stage, a high PRF pulse emission stage, and a rest stage, and the stages work alternately in sequence. The system includes two task states: the system ranging task state and the system imaging task state. In the system ranging task state, the laser emission module works in the low-frequency working mode, and the system only completes the ranging function of the target; in the system imaging task state, the laser emission module works in the composite working mode, and the system completes the imaging detection function of the target.

2. The moving target single-photon laser non-scanning imaging detection system according to claim 1, characterized in that: The single-photon ranging detector is a free-running mode or quasi-continuous mode single-photon detector.

3. The moving target single-photon laser non-scanning imaging detection system according to claim 1, characterized in that: The single-photon imaging detector is a Geiger focal plane detector, and the detector works in the gated mode.

4. The moving target single-photon laser non-scanning imaging detection system according to claim 1, characterized in that: In the low PRF emission stage, the laser pulse repetition frequency is f1, in the high PRF emission stage, the pulse repetition frequency is f2, and f1 << f2, and no laser is emitted in the rest stage.

5. The moving target single-photon laser non-scanning imaging detection system according to claim 1, characterized in that: The working method of the system ranging task state is: (1) The laser emission module works in the low-frequency working mode, sends narrow pulsed laser with a fixed pulse frequency towards the target, and outputs an optical emission synchronization signal. (2) The laser ranging receiving module receives the laser echo pulse reflected by the target and converts it into a photon counting pulse signal through the internal single-photon ranging detector. (3) The ranging signal processing module receives the photon counting signal output by the laser ranging receiving module, extracts the target echo arrival time from the counting pulse signal through the single photon ranging algorithm based on multi-path time correlation, and calculates the time difference between the optical synchronization signal and the target echo arrival time. ,pass Calculate the target distance d.

6. The moving target single-photon laser non-scanning imaging detection system according to claim 1, characterized in that: The working method of the imaging task state is: (1) The laser emission module works in the low PRF emission stage of the composite working mode, collaborates with the laser ranging receiving module and the ranging signal processing module to complete the ranging of the target, and its working method is the same as that of the ranging task state described in claim 5. (2) After completing the ranging of the target in the low PRF emission stage of the laser, extract the target distance-time function from the ranging result through the least squares method, and output the distance-time function to the timing control module. (3) During the laser high repetition rate emission phase, the timing control module receives the target distance-time function and calculates the current target distance based on the target distance-time function; (4) After receiving the laser light synchronization signal, the timing control module and the ranging signal processing module output an external trigger signal to the laser imaging receiving module after a delay according to the current distance; (5) After receiving the external trigger signal, the laser imaging receiving module works for a fixed time slot and outputs a frame of imaging detection data; (6) The imaging signal processing module receives the imaging detection data output by the laser imaging receiving module and outputs the target three-dimensional imaging through a single-photon three-dimensional reconstruction algorithm based on multi-frame time correlation; (7) During the laser rest phase, the system does not perform any processing.

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