Disposable underwater profile target laser radar detection system and method

Abstract

The invention belongs to the technical field of ocean in-situ detection, and particularly relates to an expandable underwater profile target laser radar detection system and method, and the system comprises a magnetic detection cabin and a load rejection cabin. The detection cabin comprises a detection cabin main body with a transparent whole body, a laser radar module is arranged in the detection cabin main body, the laser radar module comprises a pulse laser, a reflecting mirror, a right-angle reflecting mirror, a rotary reflecting mirror capable of rotating by 360 degrees, a telescope system, an optical filter and a photomultiplier tube, and a laser beam of the pulse laser is incident on the rotary reflecting mirror through the reflecting mirror and the right-angle reflecting mirror; light pulse echo signals reflected by the target penetrate through the detection cabin main body, are reflected by the rotary reflecting mirror, are received by the telescope system, and are detected by the photomultiplier through the optical filter; the rotary reflecting mirror, the right-angle reflecting mirror, the telescope system, the optical filter and the photomultiplier are coaxially arranged as an optical path, the optical path design blind area is small, and large-depth and large-range rapid underwater target profile detection is achieved in the system sinking process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of in-situ ocean exploration, and particularly relates to a cast-off underwater profile target laser radar detection system and method. BACKGROUND

[0002] Underwater target fine detection has wide and urgent application requirements in the fields of maritime search and rescue, ocean exploration and military investigation, and especially the short-range detection of underwater mobile small targets is an important requirement of national defense security in recent years.

[0003] Compared with conventional underwater acoustic and electromagnetic detection technologies, laser detection technology has the advantages of high resolution, good collimation and strong anti-interference capability, and can obtain higher detection accuracy and positioning accuracy for underwater target short-range detection.

[0004] The conventional ship-borne or airborne sea measurement laser radar is limited by the absorption and scattering of seawater to laser, resulting in that the detection distance is usually limited to tens of meters to hundreds of meters, especially in turbid nearshore waters, the effective detection depth is only 10-30 meters, which greatly limits the detection capability of the sea measurement laser radar on deep sea areas or long-distance targets. At the same time, when the ship-borne or airborne sea measurement laser radar is detected, the interference of the water-gas interface such as sea surface wave fluctuation, white foam and spray will not only affect the accuracy of water depth measurement, but also cause underwater target positioning deviation, which makes the sea measurement laser radar need to invest a lot of effort in signal processing and error correction in the actual application process to reduce the adverse effects of the water-gas interface.

[0005] And for the underwater laser radar system, a paraxial optical path design is usually adopted, thereby introducing a larger blind area problem in the limited underwater detection distance, and the system is usually fixed at a specific depth for single-direction detection, the detection efficiency is low, and the fast scanning detection of large depth range and long distance in abnormal areas cannot be realized, which seriously limits the practical application of the laser radar in the fields of underwater target detection, seabed observation and sea area safety.

[0006] In order to solve the problem that large depth range, large area and fast underwater target detection cannot be realized, there is an urgent need for a cast-off underwater profile target laser radar detection system and method. SUMMARY

[0007] In order to solve the defects existing in the prior art, the present application proposes a cast-off underwater profile target laser radar detection system and method, which realizes large depth range, large area and fast underwater target detection, and the scheme is as follows: On the one hand, the present application proposes a cast-off underwater profile target laser radar detection system, which comprises a detection cabin and a throw load cabin magnetically connected with the detection cabin. The detection cabin includes a transparent detection cabin body, in which a laser radar module is arranged, and the laser radar module includes a pulse laser, a reflector, a right-angle reflector, a rotating reflector, a motor, a telescope system, a filter and a photomultiplier tube. The laser beam emitted by the pulse laser passes through the reflector and the right-angle reflector, is incident on the surface of the rotating reflector, and is irradiated to the underwater target through the detection cabin body, and reflects the light pulse on the surface of the underwater target. The light pulse echo signal passes through the detection cabin body, is reflected by the rotating reflector, and is received by the telescope system, and is detected and received by the photomultiplier tube after passing through the filter. The motor is fixedly installed in the detection cabin body, and the rotating reflector is connected to the motor through a fixed mirror frame. The motor drives the fixed mirror frame to rotate, and synchronously drives the rotating reflector to achieve 360° rotation. The rotating reflector, the right-angle reflector, the telescope system, the filter and the photomultiplier tube are coaxially arranged to ensure that the transmitting and receiving optical paths are coaxial.

[0008] Furthermore, a second power supply module and a signal processing and storage module are also provided in the detection cabin body. The second power supply module is used to power the lidar module and the signal processing module. A transmitting antenna is installed on the top of the detection cabin body to transmit the data stored in the signal processing and storage module to the shore-based system via satellite. The signal processing module includes a data acquisition card and a development board; the data acquisition card is used to convert the analog current signal of the photomultiplier tube into a digital signal; the development board is used to store and process the data collected by the data acquisition card.

[0009] Furthermore, the mirror surface area of ​​the right-angle reflector is smaller than the mirror surface area of ​​the rotating reflector.

[0010] Furthermore, the detection cabin body includes a transparent detection cabin shell, a bottom plate, an intermediate plate and a top plate, the transmitting antenna is installed on the outside of the top plate, the detection cabin shell, the bottom plate and the intermediate plate are sealed to form a first pressure-resistant chamber, the detection cabin shell, the intermediate plate and the top plate are sealed to form a second pressure-resistant chamber, a circular hole is opened on the intermediate plate for light transmission, and an iron plate for magnetic connection is installed on the outside of the bottom plate; the rotating reflector, the motor and the fixed mirror holder are located in the second pressure-resistant chamber, and the motor is fixedly connected to the top plate; A mounting plate is also provided in the first pressure-resistant chamber, which is fixedly installed between the bottom plate and the middle plate. A pulse laser, a reflector, a right-angle reflector, a telescope system, a filter and a photomultiplier tube are installed on one side of the mounting plate, and a data acquisition card, a development board and a second power supply module are installed on the other side of the mounting plate.

[0011] Furthermore, the jettisoning cabin includes a jettisoning cabin main body and a counterweight installed at the bottom of the jettisoning cabin main body; a first power supply module, an electromagnet for magnetic connection, a circuit board and a pressure sensor are arranged in the jettisoning cabin main body, the first power supply module is connected to the electromagnet, and the circuit board is connected to the first power supply module and the pressure sensor respectively.

[0012] Furthermore, the jettison cabin body includes an upper end cover, a jettison cabin shell, and a lower end cover, and the jettison cabin shell is sealed to the upper end cover and the lower end cover to form a pressure-resistant cabin body; the electromagnet is installed in the upper end cover, and the upper end cover is made of magnetic conductive material; a pressure sensor is installed on the lower end cover for measuring the underwater depth of the jettison cabin; the lower end cover is also provided with a debugging and charging port for circuit debugging and / or charging the second power supply module; a fastening bolt hole is provided at the bottom of the lower end cover for installing a counterweight block.

[0013] Furthermore, the electromagnet is configured to be demagnetized when energized, maintaining magnetic force when not energized and losing magnetic force when energized.

[0014] On the other hand, the present invention provides a expendable underwater profile target laser radar detection method, which is applicable to the above-mentioned expendable underwater profile target laser radar detection system, comprising the following steps: S1. Upon discovering a suspicious target water area, the expendable underwater profile target lidar detection system is dropped into the water area; S2: The system sinks and powers on. The LiDAR module emits a laser beam, which rotates downward as the system sinks, forming a spiral scanning path. The laser beam hits the target and reflects light pulses from the target surface. The light pulse echo signal is detected and received by the photomultiplier tube and stored in the signal processing module's development board via the signal acquisition card. S3: After the system sinks to a preset depth or time, the jettison cabin is released, and the detection cabin floats up to the surface. The transmitting antenna on the detection cabin transmits data back to the shore-based system via satellite. S4. Recover the detection cabin.

[0015] Furthermore, in step S2, the laser emission beam of the pulse laser of the lidar module passes through the reflector and the right-angle reflector, and is incident on the surface of the rotating reflector that rotates 360°. It is irradiated onto the target through the detection cabin body and reflected from the target by the light pulse. The light pulse passes through the detection cabin body, is reflected by the rotating reflector, and is received by the telescope system. After passing through the filter, it is detected and received by the photomultiplier tube and converted into an analog current signal. The rotating reflector, the right-angle reflector, the telescope system, the filter and the photomultiplier tube are coaxially arranged to make the optical path coaxial for transmission and reception.

[0016] Furthermore, in step S3, the release mode of the jettisoning chamber includes a fixed depth release and a timed release; Depth release is as follows: as the system dives, the water pressure gradually increases, and the pressure sensor detects pressure data and feeds it back to the circuit board. The circuit board has a preset pressure threshold. When the detected pressure exceeds the pressure threshold, the circuit board controls the first power supply module to energize and demagnetize the electromagnet, and the jettisoning module separates from the detection cabin. The timed release is as follows: the circuit board has a built-in real-time clock to record the system's diving time. The circuit board has a preset time threshold. When the diving time is greater than the time threshold, the circuit board controls the first power supply module to energize and demagnetize the electromagnet, and the jettison cabin separates from the detection cabin.

[0017] Compared with the prior art, the advantages of the present invention are as follows: The embodiments of the present invention combine high-frequency pulsed lasers with 360-degree rotational scanning to achieve a maximum depth profile of 500 meters. The system can quickly scan and detect targets over a large range in all directions, breaking through the detection depth limitations of conventional sea-surveying lidars and greatly improving the detection efficiency and accuracy of underwater lidars.

[0018] The embodiment of the present invention adopts a coaxial optical path design for laser transmission and reception, which can greatly reduce the impact of blind spots in underwater laser radar detection.

[0019] The embodiment of the present invention adopts magnetic separation and quick release technology to achieve the quick release of the jettisoning compartment, thereby improving the reuse rate of the system at an extremely low cost.

[0020] The embodiment of the present invention improves the ability to quickly identify and locate targets in underwater abnormal areas by adopting a real-time data processing method, and also enables the system to have autonomous analysis and decision-making functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the overall structure of the expendable underwater profile target laser radar detection system according to the first embodiment of the present invention; Figure 2 1 is a schematic diagram of the internal structure of the jettison compartment according to the first embodiment of the present invention; Figure 3 This is a schematic diagram of the internal structure of the detection cabin of the first embodiment of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the internal structure of the detection cabin of the first embodiment of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of the principle flow of the laser radar module according to the first embodiment of the present invention; Figure 6 It is a schematic diagram of a model of a expendable underwater profile target laser radar detection system according to the first embodiment of the present invention.

[0022] In the above figures: 1. jettison; 1.3. upper end cover; 1.4. electromagnet; 1.5. jettison housing; 1.6. battery; 1.7. pressure sensor; 1.8. circuit board; 1.9. lower end cover; 1.10. debugging and charging port; 2. detection cabin; 2.1. pulse laser; 2.2. reflector; 2.3. photomultiplier tube; 2.4. filter; 2.5. telescope system; 2.6. right-angle reflector; 2.7. Fixed mirror frame; 2.8. Rotating reflector; 2.9. Precision motor; 2.10. Development board; 2.11. Data acquisition card; 2.12. Battery; 2.13. Transmitting antenna; 2.14. Detection cabin shell; 2.15. Bottom plate; 2.16. Middle plate; 2.17. Top plate; 2.18. Mounting plate; 4. Connecting bolts; 5. Iron plate; 6. Fastening bolts; 7. Counterweight; 8. Transmitting antenna. DETAILED DESCRIPTION

[0023] To facilitate those skilled in the art to understand the present invention, specific embodiments of the present invention are described below with reference to the accompanying drawings. Example 1

[0024] like Figures 1 to 6 As shown, the present invention proposes a expendable underwater profile target laser radar detection system, which mainly includes two parts: a jettisoning cabin 1 and a detection cabin 2. The first power supply module, electromagnet 1.4, circuit board and sensor are arranged inside the jettisoning cabin 1, and a counterweight block 7 is installed at the bottom. The second power supply module, laser radar module and signal processing module are arranged inside the detection cabin 2, and a transmitting antenna for communication is installed on the top. The jettisoning cabin 1 and the detection cabin 2 are connected by the iron plate 5 and the electromagnet 1.4, and the iron plate 5 is fixed to the bottom of the detection cabin 2 with four fastening bolts 4. The system is an underwater in-situ self-contained working mode, adopts a sealed cabin design, and has a designed pressure resistance depth of 500m.

[0025] Working Principle: The system operates after entering the water. As it descends, it emits a laser beam. When the laser strikes an underwater target, the system receives the reflected echo signal, thereby obtaining information about the target's position, depth, and distance. Once the device reaches a certain depth, the jettisoning capsule 1 is released, and the detection capsule 2, carrying the data, rises to the surface due to its own buoyancy. The transmitting antenna on the capsule then transmits the data back to the shore-based system via satellite.

[0026] Functional mechanism of each major component: 1. Dump bay 1: The structure of the jettisoning cabin 1 is mainly composed of the jettisoning cabin main body and the counterweight 7. The counterweight 7 is fastened to the bottom of the cabin main body by fastening bolts 6. When the system reaches the specified time or depth, the jettisoning cabin main body and the counterweight 7 are automatically separated from the iron plate 5 to realize the jettisoning function. The iron plate 5 is fixedly connected to the top of the jettisoning cabin main body by connecting screws 4. The jettisoning cabin 1 uses its own structure as part of the ballast weight, thereby offsetting part of the rising buoyancy of the detection cabin 2 to the greatest extent, and improving the flexibility of the system design. The jettisoning cabin 1 is an independent structure, which is easy to install and replace, and has a simple structure, and is stable and reliable.

[0027] The jettisoning compartment body comprises an upper end cover 1.3, a housing 1.5, and a lower end cover 1.9. The housing 1.5 is a pressure-resistant shell, sealed between the end face of the shell and the end cover with an O-ring, forming a pressure-resistant compartment. An electromagnet 1.4 is mounted within the upper end cover 1.3. The upper end cover 1.3 is made of a magnetically conductive material, which not only seals the electromagnet 1.4 but also directs its magnetic force. A pressure sensor 1.7 is mounted on the lower end cover 1.9, which accurately measures the underwater depth of the jettisoning device and provides water pressure data for subsequent depth-determined release. The lower end cover 1.9 also features a debugging and charging port 1.10, which allows for parameter presets and battery charging. Fastening bolt holes are provided at the bottom of the lower end cover 1.9 for mounting a counterweight 7. The counterweight 7 is configured as an inverted pyramid and is securely connected to the lower end cover 1.9 via fastening bolts 6.

[0028] A first power supply module and a circuit board 1.8 are arranged inside the jettisoning cabin body. The first power supply module is connected to the electromagnet 1.4. In this embodiment, the first power supply module is a battery 1.6. The circuit board 1.8 is electrically connected to the electromagnet 1.4, the pressure sensor 1.7, and the jettisoning battery 1.6, respectively. The electromagnet 1.4 is of the energized demagnetization type. When not energized, it can maintain the attraction force on the iron disk 5. When energized, the electromagnet 1.4 loses its magnetic force and, under the action of gravity, separates from the iron disk 5, allowing the jettisoning cabin 1 to be jettisoned and the detection cabin 2 to float and be recovered. Experimental verification has shown that this technology can effectively improve the reuse rate of the system at a very low cost.

[0029] The release mode of the jettisoning chamber 1 supports fixed-depth release or timed release. The circuit board 1.8 has a built-in microcontroller that can control the charge management and voltage stabilization control of the battery 1.6. During the system's dive, the water pressure gradually increases, and the pressure sensor 1.7 detects the pressure data and feeds it back to the microcontroller. The microcontroller sets a pressure threshold. When the detected pressure is greater than the preset pressure threshold, the electromagnet 1.4 is controlled to be energized and demagnetized, and the jettisoning chamber 1 is separated from the detection chamber 2 to achieve fixed-depth release. The circuit board 1.8 has a built-in real-time clock to record the system's dive time. The microcontroller is set with a time threshold. When the dive time exceeds the set time threshold, the electromagnet 1.4 is controlled to be energized and demagnetized, and the jettisoning chamber 1 is separated from the detection chamber 2 to achieve timed release. The dual release mode of depth and time is adopted to improve the applicability of the system. 2. Detection Module 2: The detection cabin 2 is the core part of the expendable underwater profile target laser radar detection system, and is mainly responsible for laser emission, target detection and data return. The detection cabin 2 includes a detection cabin body, inside which the second power supply module, laser radar module, and signal processing module are arranged, and a transmitting antenna is installed on the outside of the detection cabin body. The detection cabin body includes a detection cabin shell 2.14, a bottom plate 2.15, an intermediate plate 2.16 and a top plate 2.17. The transmitting antenna is installed on the outside of the top plate 2.17. The detection cabin shell 2.14, the bottom plate 2.15 and the intermediate plate 2.16 made of transparent material form a first pressure-resistant chamber, and the detection cabin shell 2.14, the intermediate plate 2.16 and the top plate 2.17 form a second pressure-resistant chamber. A circular hole is opened on the intermediate plate 2.16 for light transmission, and an iron plate is installed on the outside of the bottom plate 2.15 by screws. A mounting plate 2.18 is also provided within the first pressure-resistant chamber. This mounting plate 2.18 is fixedly mounted between the bottom plate 2.15 and the middle plate 2.16. O-rings are used to seal the detection chamber housing 2.14 against the bottom plate 2.15, the middle plate 2.16, and the top plate 2.17, forming a pressure-resistant chamber. The mounting plate 2.18 is double-sided. For ease of distinction, one side is defined as the top side of the mounting plate 2.18, and the other side is defined as the bottom side.

[0030] In order to facilitate the generation of high repetition rate pulse beams and the reception of underwater target echo signals, the detection cabin shell 2.14 is configured as a ring-shaped acrylic transparent window.

[0031] A laser radar module is installed within the detection cabin 2. To achieve long-range, wide-area target detection, the laser radar module includes a pulsed laser 2.1, a reflector 2.2, a right-angle reflector 2.6, a 360° rotatable rotating mirror 2.8, and a precision motor 2.9. These components are mounted on a mounting plate 2.18, while the precision motor 2.9 is fixedly mounted on a top plate 2.17. The rotating mirror 2.8 is connected to the precision motor 2.9 via a fixed mirror mount 2.7. The precision motor 2.9 drives the fixed mirror mount 2.7 to rotate, which in turn drives the rotating mirror 2.8 to achieve 360° rotation. In this embodiment, a high-repetition-rate, 532nm-wavelength pulsed laser 2.1 is employed. The laser beam, after passing through a reflector 2.2 and a right-angle reflector 2.6, is incident on a rotating reflector 2.8, which is driven by a precision motor 2.9 and capable of 360° rotation. Rotating reflector 2.8 is connected to precision motor 2.9 via a fixed mirror mount 2.7. The system uses an annular, transparent acrylic detection chamber housing 2.14 as a circular window for rotating high-repetition-rate pulsed beams, forming a spiral scanning path across the cross-sectional detection area as the system depth increases. Simultaneously, the echo signal from the underwater target passes through the annular window and rotating reflector 2.8 before being received by a telescope system 2.5. After passing through a filter 2.4, the final optical signal is detected and received by a highly sensitive photomultiplier tube (PMT) 2.3, where it is converted into an electrical signal. (See reference to the following text.) Figure 4 .like Figure 3 、 4 As shown, the rotating reflector 2.8, the right-angle reflector 2.6, the telescope system 2.5, the filter 2.4 and the photomultiplier tube 2.3 are coaxially arranged to make the optical transmission and reception coaxial, wherein the telescope system 2.5, the filter 2.4 and the photomultiplier tube 2.3 are all located on the mounting plate 2.18.

[0032] In the optical path structure of the lidar module, we adopted a coaxial optical path structure design, that is, the transmission and reception are on the same axis. Compared with the existing technology that uses a paraxial optical path design for detection, which cannot avoid the problem of large blind spots, the optical path structure design of this application can greatly reduce the impact of the underwater lidar detection blind spot. Even if the laser energy decays exponentially in the water, the system can still ensure the ability to detect targets in a large circumferential range in the water.

[0033] The signal processing module includes a data acquisition card 2.11 and a development board 2.10, both of which are installed under the mounting plate 2.18. The present invention uses a data acquisition card with a high acquisition rate to obtain echo signals at different times, and then calculate the distance information of the underwater target. During the data acquisition process, the pulse laser 2.1 externally triggers the working mode of the data acquisition card 2.11 to achieve synchronization of laser emission and signal acquisition. The development board 2.10 is used to store and process the data collected by the data acquisition card. The present invention selects a development board with stable performance because it has the characteristics of small size and rich bus interfaces, making it an ideal control and data processing platform. During the entire in-situ profile measurement process, the system is able to achieve self-starting, self-measurement, and self-storage working modes.

[0034] The transmitting antenna uses an integrated shallow sea Iridium antenna 2.13, which is not only small in size and light in weight, but also can withstand an underwater pressure of 1,000 meters.

[0035] The second power supply module is used to power the devices in the detection cabin 2. The second power supply module of the present invention is configured as a battery. The system is configured with a high-capacity detection battery 2.12, which is specifically installed under the mounting plate 2.18.

[0036] The system uses an autonomous decision-making algorithm for underwater target detection, which is set in the development board 2.10. Through efficient and accurate real-time data processing, it can quickly identify and locate abnormal underwater targets, thereby improving the effectiveness and reliability of the system in actual marine environments.

[0037] Specifically, the autonomous decision-making algorithm includes the following steps: The first step is to obtain effective underwater target signals by preprocessing the data. The collected raw data undergoes filtering, denoising, and normalization to remove interference from water scattering noise and electronic device noise, accurately extracting the target's echo signal characteristics. This improves data quality while also obtaining target distance information. The second step is to build a deep learning-based convolutional neural network model. By training the model with a large number of labeled echo signals, the model can rapidly identify and classify different types of underwater targets. Example 2

[0038] The present invention also provides a expendable underwater profile target laser radar detection method, which is applicable to the above-mentioned expendable underwater profile target laser radar detection system, comprising the following steps: S1. After discovering a suspicious target water area, the drone transports the system to the water area and drops the system; S2. The system is put into operation underwater and powered on. The laser radar module emits a laser beam. As the system sinks, the laser beam rotates downward in a spiral, irradiating the target and reflecting light pulses from the target. The light pulse echo signal is detected and received by the photomultiplier tube 2.3 and stored in the signal processing module's development board 2.10 via the signal processing module's data acquisition card 2.11. Specifically, the laser emission beam of the pulse laser 2.1 of the lidar module passes through the reflector 2.2 and the right-angle reflector 2.6, and is incident on the surface of the 360-degree rotating rotating reflector 2.8. It then passes through the detection cabin body and irradiates the target and reflects the light pulse from the target. The light pulse passes through the detection cabin body, is reflected by the rotating reflector 2.8, and is received by the telescope system 2.5. After passing through the filter 2.4, it is detected and received by the photomultiplier tube 2.3 and converted into an analog current signal. The rotating reflector 2.8, the right-angle reflector 2.6, the telescope system 2.5, the filter 2.4 and the photomultiplier tube 2.3 are coaxially arranged to ensure that the optical path is coaxial for transmission and reception, and the influence of the blind spot can be ignored, which greatly reduces the influence of the underwater lidar detection blind spot. Even if the laser energy decays exponentially in the water, the ability to detect targets in a large range in the water can still be guaranteed.

[0039] S3. After sinking to a preset depth or time, the jettisoning module 1 is released, and the detection module 2 floats up to the surface. The transmitting antenna on the detection module 2 transmits data back to the shore-based system via satellite. The circuit board controls the electromagnet 1.4 to be energized, and the electromagnet 1.4 loses its magnetic force. Under the action of gravity, the electromagnet 1.4 is separated from the iron plate 5 of the detection cabin, thereby releasing the jettison cabin 1.

[0040] Specifically, the release mode of the jettisoning chamber 1 includes fixed depth release and timed release; More specifically, the fixed-depth release is as follows: as the system dives, the water pressure gradually increases, and the pressure sensor 1.7 detects pressure data and feeds it back to the circuit board 1.8. The circuit board 1.8 has a preset pressure threshold. When the detected pressure exceeds the pressure threshold, the circuit board 1.8 controls the first power supply module to energize and demagnetize the electromagnet 1.4, causing the jettisoning chamber 1 to separate from the detection chamber 2 and release the jettisoning chamber 1. More specifically, the timed release is as follows: the circuit board 1.8 has a built-in real-time clock for recording the system diving time, and a time threshold is preset in the circuit board 1.8. When the diving time is greater than the time threshold, the circuit board 1.8 controls the first power supply module to energize and demagnetize the electromagnet 1.4, and the jettisoning cabin 1 separates from the detection cabin 2 to realize the release of the jettisoning cabin 1.

[0041] S4. Recover detection cabin 2.

[0042] The above-described embodiments of the present invention do not limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A disposable underwater profile target laser radar detection system, characterized in that: It comprises a detection cabin (2) and a jettison cabin (1) magnetically connected to the detection cabin (2); The detection cabin (2) includes a transparent detection cabin body, in which a laser radar module is arranged. The laser radar module includes a pulse laser (2.1), a reflector (2.2), a right-angle reflector (2.6), a rotating reflector (2.8), a motor (2.9), a telescope system (2.5), a filter (2.4) and a photomultiplier tube (2.3). The laser beam emitted by the pulse laser (2.1) passes through the reflector (2.2) and the right-angle reflector (2.6), is incident on the surface of the rotating reflector (2.8), and passes through the detection cabin body. The light pulse is irradiated onto the underwater target and reflected on the surface of the underwater target. The light pulse echo signal passes through the detection cabin body, is reflected by the rotating reflector (2.8), is received by the telescope system (2.5), and is detected and received by the photomultiplier tube (2.3) after passing through the filter (2.4). The motor (2.9) is fixedly installed in the detection cabin body, and the rotating reflector (2.8) is connected to the motor (2.9) through the fixed mirror frame (2.7). The motor (2.9) drives the fixed mirror frame (2.7) to rotate, and synchronously drives the rotating reflector (2.8) to achieve 360° rotation. The rotating reflector (2.8), the right-angle reflector (2.6), the telescope system (2.5), the filter (2.4) and the photomultiplier tube (2.3) are coaxially arranged to make the light path transmitting and receiving coaxial.

2. The expendable underwater profile target laser radar detection system according to claim 1, characterized in that: A second power supply module and a signal processing and storage module are also provided in the detection cabin body, wherein the second power supply module is used to supply power to the laser radar module and the signal processing module. A transmitting antenna (8) is installed on the top of the detection cabin body, and is used to transmit the data stored in the signal processing and storage module to the shore-based system via a satellite. The signal processing module includes a data acquisition card (2.11) and a development board (2.10); the data acquisition card (2.11) is used to convert the analog current signal of the photomultiplier tube (2.3) into a digital signal; and the development board (2.10) is used to store and process the data acquired by the data acquisition card.

3. The expendable underwater profile target laser radar detection system according to claim 1, characterized in that: The mirror surface area of ​​the right-angle reflector (2.6) is smaller than the mirror surface area of ​​the rotating reflector (2.8).

4. The expendable underwater profile target laser radar detection system according to claim 2, characterized in that: The detection cabin body comprises a transparent detection cabin shell (2.14), a bottom plate (2.15), an intermediate plate (2.16) and a top plate (2.17); the transmitting antenna is installed on the outside of the top plate (2.17); the detection cabin shell (2.14), the bottom plate (2.15) and the intermediate plate (2.16) are sealed to form a first pressure-resistant chamber; the detection cabin shell (2.14), the intermediate plate (2.16) and the top plate (2.17) are sealed to form a second pressure-resistant chamber; a circular hole is provided on the intermediate plate (2.16) for light transmission; an iron plate (5) for magnetic connection is installed on the outside of the bottom plate (2.15); the rotating reflector (2.8), the motor (2.9) and the fixed mirror frame (2.7) are located in the second pressure-resistant chamber; the motor (2.9) is fixedly connected to the top plate (2.17); A mounting plate (2.18) is also provided in the first pressure-resistant chamber. The mounting plate (2.18) is fixedly installed between the bottom plate (2.15) and the middle plate (2.16). A pulse laser (2.1), a reflector (2.2), a right-angle reflector (2.6), a telescope system (2.5), a filter (2.4), and a photomultiplier tube (2.3) are installed on one side of the mounting plate (2.18), and a data acquisition card (2.11), a development board (2.10), and a second power supply module are installed on the other side of the mounting plate (2.18).

5. The expendable underwater profile target laser radar detection system according to claim 1, characterized in that: The jettisoning cabin (1) comprises a jettisoning cabin main body and a counterweight (7) mounted on the bottom of the jettisoning cabin main body; a first power supply module, an electromagnet (1.4) for magnetic connection, a circuit board (1.8) and a pressure sensor (1.7) are arranged in the jettisoning cabin main body; the first power supply module is connected to the electromagnet (1.4), and the circuit board (1.8) is respectively connected to the first power supply module and the pressure sensor (1.7).

6. The expendable underwater profile target laser radar detection system according to claim 5, characterized in that: The jettison cabin body comprises an upper end cover (1.3), a jettison cabin shell (1.5), and a lower end cover (1.9); the jettison cabin shell (1.5) is sealedly connected to the upper end cover (1.3) and the lower end cover (1.9) to form a pressure-resistant cabin; the electromagnet (1.4) is installed in the upper end cover (1.3), and the upper end cover (1.3) is made of a magnetic conductive material; a pressure sensor (1.7) is installed on the lower end cover (1.9) for measuring the underwater depth of the jettison cabin (1); the lower end cover (1.9) is also provided with a debugging charging port (1.10) for circuit debugging and / or charging the second power supply module; and a fastening bolt hole (6) is provided at the bottom of the lower end cover (1.9) for installing a counterweight (7).

7. The expendable underwater profile target laser radar detection system according to claim 5, characterized in that: The electromagnet (1.4) is configured as a power-on demagnetization type, maintaining magnetic force when not powered and losing magnetic force when powered.

8. A method for detecting underwater profile targets using a expendable laser radar, applicable to the expendable laser radar detection system for underwater profile targets according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Upon discovering a suspicious target water area, the expendable underwater profile target lidar detection system is dropped into the water area; S2. The system sinks and powers on. The laser radar module emits a laser beam. As the system sinks, the laser beam rotates downward to form a spiral scanning path. The laser beam hits the target and reflects light pulses from the target surface. The light pulse echo signal is detected and received by the photomultiplier tube (2.3) and stored in the signal processing module's development board (2.10) via the signal processing module's data acquisition card (2.11). S3, after the system sinks to a preset depth or time, the jettison cabin (1) is released, the detection cabin (2) floats up to the water surface, and the transmitting antenna on the detection cabin (2) transmits the data back to the shore-based system via a satellite; S4. Recover the detection cabin (2).

9. The method for detecting underwater profile targets by a disposable laser radar according to claim 8, characterized in that: In step S2, the laser emission beam of the pulse laser (2.1) of the laser radar module passes through the reflector (2.2) and the right-angle reflector (2.6), and is incident on the surface of the rotating reflector (2.8) that rotates 360 degrees. The light pulse is irradiated onto the target through the detection cabin body and reflected from the target. The light pulse is received by the telescope system (2.5) after passing through the detection cabin body and the rotating reflector (2.8). After passing through the filter (2.4), the light pulse is detected and received by the photomultiplier tube (2.3) and converted into an analog current signal. The rotating reflector (2.8), the right-angle reflector (2.6), the telescope system (2.5), the filter (2.4) and the photomultiplier tube (2.3) are coaxially arranged so that the optical path for transmission and reception is coaxial.

10. The method for detecting underwater profile targets by a disposable laser radar according to claim 8, characterized in that: In step S3, the release mode of the jettison (1) includes a fixed depth release mode and a timed release mode; The fixed depth release is as follows: the system dives, the water pressure gradually increases, the pressure sensor (1.7) detects the pressure data and feeds it back to the circuit board (1.8), the circuit board (1.8) has a preset pressure threshold, and when the detected pressure is greater than the pressure threshold, the circuit board (1.8) controls the first power supply module to energize and demagnetize the electromagnet (1.4), and the jettisoning cabin (1) separates from the detection cabin (2); The timed release is as follows: a real-time clock is built into the circuit board (1.8) to record the diving time of the system, and a time threshold is preset in the circuit board (1.8). When the diving time is greater than the time threshold, the circuit board (1.8) controls the first power supply module to energize and demagnetize the electromagnet (1.4), and the jettisoning cabin (1) is separated from the detection cabin (2).

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