A large-dynamic adaptive laser detection and tracking device and method for ship wake

Abstract

The present invention belongs to the technical field of underwater laser detection and guidance, and discloses a large-dynamic adaptive laser detection and tracking device and method for ship wakes, including a laser emission system, a multi-channel receiving system, an APD adaptive gain control system, and a signal processing system. Based on the theory of laser backscattering detection of ship wakes and the loading requirements such as volume, size, weight, high and low temperature, and anti-load impact that need to be satisfied for the application of wake laser detection, the present invention designs a ship wake laser detection system suitable for loading on an underwater vehicle. In the laser emission module, a semiconductor-pumped solid-state laser is selected, and an expanding and collimating system is designed by using the relationship between the beam angle, focal length, and light-emitting aperture, so as to realize controllable adjustment of the laser emission energy and repetition frequency; in the multi-channel receiving system, a multi-channel detection and receiving system is adopted; the APD gain is controllably adjusted by using a digital potentiometer, so as to realize the detection and reception of short pulses and large-dynamic laser echoes.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater laser detection and guidance, and particularly relates to a large-dynamic adaptive ship wake laser detection and tracking device and method. Background Art

[0002] At present, when a ship moves in water, especially on the water surface, it will inevitably generate a wake. The so-called wake is a long wake area containing a large number of bubbles formed in the seawater at the stern of the ship during navigation due to the cavitation of the propeller, the breaking of sea waves, and the entrainment of a large amount of air in the hull waterline part. Currently, the acoustic wake homing device is the one that has been truly applied in practice and has good combat use effects. However, the traditional acoustic wake homing device has problems such as large self-noise interference, being greatly affected by sea conditions, seawater temperature gradient, etc. At the same time, as the speed of the vehicle increases, the platform noise increases sharply, further reducing the performance of the acoustic detection system. It is difficult for an underwater high-speed vehicle to carry an acoustic detection device to detect the weak bubbles in the far field of the ship wake with high precision, which limits the speed of the underwater vehicle and the combat use distance of terminal precise guidance. Due to the short wavelength of the laser, by using the Mie scattering effect of the wake bubbles on the laser, the laser can be made to be much more sensitive to the change of the propagation medium than the sound wave, and it is less affected by water temperature and noise. It can be carried on a high-speed moving carrier to detect the micro-bubbles in the ship wake with high precision, improving the guidance distance and speed of the underwater vehicle in combat use.

[0003] By using the Mie backward scattering characteristics of the ship wake bubbles on the laser, a laser detection device can be used to detect the micro-bubble group in the ship wake, and when carried on an underwater vehicle, it can achieve accurate strikes on the ship. However, the backscattering echo signal of the water body is relatively strong, and the strong water body signal in the near field can easily cause the signal saturation of the receiving system, and the far-field target echo signal of the system is easily submerged in the water body backscattering background signal.

[0004] Through the above analysis, the problems and defects existing in the prior art are as follows: The existing laser detection device can achieve accurate strikes on the ship by being carried on an underwater vehicle. However, the backscattering echo signal of the water body is relatively strong, and the strong water body signal in the near field can easily cause the signal saturation of the receiving system, and the far-field target echo signal of the system is easily submerged in the water body backscattering background signal. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a large-dynamic adaptive ship wake laser detection and tracking device and method.

[0006] The present invention is implemented as follows. A large-dynamic adaptive ship wake laser detection and tracking device includes:

[0007] A laser emission system is used to design a beam expanding and collimating system based on the relationship between the beam angle, focal length, and light output aperture of a semiconductor-pumped solid laser, enabling controllable adjustment of the laser emission energy and repetition frequency.

[0008] A multi-channel receiving system uses a multi-channel detection and receiving method to obtain photons scattered back after a laser beam collides with the surface of the wake bubbles of a ship.

[0009] An APD adaptive gain control system is connected to the multi-channel receiving system and is used to achieve controllable adjustment of the APD gain using a digital potentiometer, enabling detection and reception of short-pulse and large-dynamic laser echoes.

[0010] A signal processing system is connected to the APD adaptive gain control system and is used to process signals.

[0011] Furthermore, the laser emission system consists of a laser, a power supply, a beam expanding and collimating device, and an integrated processing and display control module. The laser is respectively connected to the power supply, the beam expanding and collimating system, and the integrated processing and display control module. The beam expanding and collimating system and the integrated processing and display control module are connected to a computer host.

[0012] The beam expanding and collimating device realizes the function of electric focus adjustment through the computer host, controlling the change of the laser emission beam angle. The integrated processing and display control module is used to adjust the parameters of the laser switch and energy magnitude by controlling the current of the drive module and the TEC temperature control module.

[0013] Furthermore, the multi-channel receiving system includes multiple receiving channels set at different axial distances, and the optimal receiving distances corresponding to the receiving channels at different axial distances are different.

[0014] Furthermore, the APD adaptive gain control system includes an optical receiving structure, an optical fiber, an APD detector, and a filtering device. The light reflected by the target is focused on the optical fiber through a convex lens and the filtering device, and is coupled into the APD detector through the optical fiber.

[0015] Furthermore, the APD detector adjusts the photocurrent gain of the APD detector by adjusting the magnitude of the bias voltage of the APD detector using the relationship between the dark current, photocurrent, and bias voltage.

[0016] Furthermore, the APD detector sends a setting command through the IIC interface, which can adjust the contact position of the potentiometer, thereby changing the output voltage. The APD gain is divided into 256 levels.

[0017] Furthermore, the signal processing system consists of an amplifier circuit, a conditioning circuit, a high-speed ADC acquisition circuit, and a processing circuit.

[0018] The amplification circuit is used for the signal generated by the APD detector cannot be directly transmitted and needs to be amplified.

[0019] The conditioning circuit is used for analog filtering the amplified signal, converting the signal from single-ended to differential to match the high-speed ADC input interface, and obtaining an electrical signal that meets the requirements of the subsequent circuit.

[0020] The high-speed ADC acquisition circuit is used for acquiring the signal.

[0021] The processing circuit is used for detecting and filtering the signal.

[0022] Another object of the present invention is to provide a large-dynamic adaptive ship wake laser detection and tracking method. The large-dynamic adaptive ship wake laser detection and tracking method includes:

[0023] Step 1: The computer upper computer outputs a control instruction to control the laser to output pulsed laser. After collimating the output pulsed laser, it is incident into the water environment. A large number of photons are absorbed or scattered by the water body. The scattered photons are received by the multi-channel receiving system and then transmitted to the APD adaptive gain control system through optical fiber. The system collects and processes the light scattering intensity of the natural water body. Through multiple cumulative measurements and adjusting parameters such as the laser emission energy, frequency, and the receiving gain of the APD, the best emission and receiving system parameters of the measurement water area and the normalized natural water body signal characteristics of the measurement water area are obtained.

[0024] Step 2: When the detection device enters the wake area, the laser beam composed of a large number of photons collides with the natural water body and the surface of the ship wake bubbles. A large number of photons are absorbed or scattered by the natural water body and bubbles. The scattered photons are received by the multi-channel receiving system and then transmitted to the APD adaptive gain control system through optical fiber. According to the normalized natural water body signal characteristics obtained in Step 1, the background interference of the natural water body is filtered out through cumulative correlation processing, and an extremely weak wake bubble scattering signal is obtained.

[0025] Step 3: Finally, the signal is output to the signal processing system for signal processing, transmitted to the oscilloscope through the BNC line for displaying images, and finally the detection information is displayed. Through multiple cumulative detections, processing, and continuous judgments, the detection of the ship wake state is realized, and further the underwater vehicle is tracked to follow the ship wake.

[0026] Further, in the output control instruction of the computer upper computer to control the laser to output pulsed laser in Step 1, the computer upper computer adjusts parameters such as the switch, energy size, and repetition frequency of the laser, transmits the information to the integrated processing and display control module, and the integrated processing and display control module adjusts parameters such as the switch and energy size of the laser by controlling the current of the drive module and the TEC temperature control module.

[0027] Furthermore, the drive circuit drives the internal emission of 808 nm pump light in the laser according to the information conveyed by the integrated processing and display control module. The pump light irradiates the laser working substance, and after a delay of 200 μs, a Q-switching signal is generated. A high-voltage signal is generated by the Q-switching module to control the generation of 1064 nm laser, which is frequency-doubled to 532 nm by OPO and emitted through the beam expander and collimator device.

[0028] Combined with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0029] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving this problem, closely combining the technical solutions to be protected by the present invention and the results and data during the R & D process, etc., analyze in detail and profoundly how the technical solutions of the present invention solve the technical problems and the creative technical effects brought after solving the problems. The specific description is as follows:

[0030] Based on the theory of laser backscattering detection of ship wakes and the loading requirements such as volume, size, weight, high and low temperature, and anti-load impact required for the application of wake laser detection, the present invention designs a ship wake laser detection system suitable for underwater vehicle loading. In the laser emission system, a semiconductor-pumped solid-state laser is selected, and a beam expander and collimator system is designed using the relationship between the beam angle, focal length, and light output aperture, which can realize controllable adjustment of the laser emission energy and repetition frequency; in the multi-channel receiving system, a multi-channel detection and receiving system is adopted; in the APD adaptive gain control system, a digital potentiometer is used to realize controllable adjustment of the APD gain, which can realize the detection and reception of short pulses and large-dynamic laser echoes.

[0031] The present invention utilizes the Mie backscattering characteristics of ship far-field wake bubbles, uses a highly sensitive and large-dynamic laser detection device to detect the ship wake bubble group, and is carried on an underwater vehicle to achieve accurate strikes on ships.

[0032] By designing a multi-channel distributed receiving technology and an adaptive gain adjustment module, the present invention combines the APD adaptive large-dynamic range and high-sensitivity detection with multi-channel distributed receiving. The structure design is relatively simple and the cost is low. It can effectively suppress the backscattering of seawater and improve the detection signal-to-noise ratio of ship wake bubbles, and enhance the reliability and combat range of underwater vehicles in wake guidance.

[0033] The present invention combines the APD adaptive large-dynamic range and high-sensitivity detection with multi-channel distributed receiving. The structure is simple and the cost is low. It can effectively shield the strong scattering interference of the near-distance water body, and then realize the high-sensitivity detection of the weak bubble echo of the ship wake under the strong reverberation background. It can replace the range-gating mode to a certain extent.

[0034] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows

[0035] The present invention has a relatively simple structural design and low cost, improving the detection sensitivity of discrete and sparse ship wake bubbles under strong reverberation background. An APD adaptive gain controllable adjustment module is designed using a digital potentiometer, significantly enhancing the environmental adaptability of the detection system and the ability to detect weak bubble wake laser echoes under the background of large dynamic range, strong reverberation, and strong noise. Furthermore, the reliability and environmental adaptability of the underwater vehicle in wake guidance are improved.

[0036] Third, as the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0037] (1) The expected benefits and commercial value after the transformation of the technical solution of the present invention are as follows: The technical solution of the present invention has passed the test verification of equivalently simulating ship wake bubbles under the background of complex indoor water bodies and the test in the outdoor lake environment, verifying the environmental adaptability of the technical solution. After the transformation of the technical solution in the next step, a large dynamic adaptive control and detection module in the underwater laser detection system can be formed, which should be used in fields such as ship wake detection, underwater obstacle detection, fishing net detection, and underwater topography survey, reducing the system implementation cost, enhancing the environmental adaptability and reliability of the system, and having broad commercial value.

[0038] (2) The technical solution of the present invention fills the technical gaps in the domestic and international industries: Currently, domestic relevant researchers mostly use methods such as range-gated imaging, polarization detection, and pulsed laser backscattering to detect ship wakes in ship wake laser detection. Most of them have designed prototype systems to conduct corresponding detection experiments on ship wake bubbles, but the achieved effects still lag behind those of foreign countries. The specific reason is that ship wake bubbles are sparse and discrete, the laser detection echo signal is weak, and the system's environmental adaptability is poor. The present invention can effectively match the ship wake laser detection system with the water environment and ship wake bubble targets, filling the long-term technical gap that restricts the high-sensitivity and large-dynamic detection of weak bubbles under strong reverberation background.

[0039] (3) The technical solution of the present invention solves the technical problems that people have been eager to solve but have never been successful:

[0040] By means of multi-channel distributed reception, adaptive gain control technology, etc. of the present invention, the weak signal processing of wake bubble laser echoes is realized, the ability to detect weak bubble wake laser echoes under the background of large dynamic range and strong noise is enhanced, the engineering of the wake laser detection system can be rapidly promoted, and the technical problem that has long restricted the detection of extremely weak targets by underwater laser detection systems under strong reverberation background is solved. Description of the Drawings

[0041] Figure 1 is a schematic structural diagram of a large-dynamic adaptive ship wake laser detection and tracking device provided by an embodiment of the present invention;

[0042] Figure 2 is a principle block diagram of the connection of a large-dynamic adaptive ship wake laser detection and tracking device provided by an embodiment of the present invention;

[0043] Figure 3 is a block diagram of the structure of a laser emission system provided by an embodiment of the present invention;

[0044] Figure 4 is a schematic diagram of the principle of an expanding and collimating device provided by an embodiment of the present invention;

[0045] Figure 5a is a schematic diagram of the relationship between the emission and reception fields of view of a multi-channel reception system provided by an embodiment of the present invention;

[0046] Figure 5b is the present invention Figure 5a longitudinal sectional view at position 1;

[0047] Figure 5c is the present invention Figure 5a longitudinal sectional views at positions 2, 3, and 4;

[0048] Figure 5d is the present invention Figure 5a transverse sectional view of the emission channel and the near, middle, and far-field reception channels;

[0049] Figure 6 is a schematic diagram of the structure principle of an APD adaptive gain control system provided by an embodiment of the present invention;

[0050] Figure 7 is a schematic diagram of the principle of an improved APD bias power supply provided by an embodiment of the present invention;

[0051] Figure 8 is a block diagram of the structure of a signal processing system provided by an embodiment of the present invention;

[0052] In the figure: 1. Computer host; 2. Laser; 3. Pulse laser; 4. Ship wake bubbles; 5. Multi-channel reception system; 6. Detector control cable; 7. APD adaptive gain control system; 8. Oscilloscope; 9. Optical fiber; 10. Signal processing system. Detailed Embodiments

[0053] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in combination with embodiments. It should be understood that the specific embodiments described herein are merely used to explain the present invention and are not used to limit the present invention.

[0054] I. Explanation of the embodiments. In order to enable those skilled in the art to fully understand how the present invention is specifically implemented, this part is an explanatory embodiment that expands on the technical solutions of the claims.

[0055] As Figure 1 and Figure 2 shown, the large dynamic adaptive ship wake laser detection and tracking device provided by the embodiments of the present invention includes a laser emission system, a multi-channel receiving system 5, an APD adaptive gain control system 7, and a signal processing system 10. The electrolytic molybdenum wire and the air pump air flow are used to release through the ceramic tube to equivalently simulate wake bubbles with different scale characteristics in the indoor laboratory environment.

[0056] Among them, the laser emission system is composed of a laser 2, a power supply, a beam expanding and collimating system, and an integrated processing and display control module. The parameters such as the switch, energy size, and repetition frequency of the laser are adjusted through the computer host control software, and the information is sent to the integrated processing and display control module. The integrated processing and display control module adjusts the parameters such as the switch and energy size of the laser by controlling the current of the driving module and the TEC temperature control module. The driving circuit drives the internal emission of 808nm pump light in the laser according to the information sent by the integrated processing and display control module. The pump light irradiates the laser working substance, and after a delay of 200μs, a Q-switching signal is generated. A high-voltage signal is generated by the Q-switching module to control the generation of 1064nm laser, which is frequency-doubled to 532nm by OPO and emitted through the beam expanding and collimating device.

[0057] The multi-channel receiving system 5 needs to be installed on the underwater vehicle carrier, and has high requirements for the volume, weight, size, and anti-impact performance of the equipment. Considering the engineering application background of wake laser detection, a multi-channel detection system is designed. By combining APD adaptive large dynamic range high-sensitivity detection with multi-channel distributed reception, the structure is simple and the cost is low. It can effectively shield the strong scattering interference of the near-distance water body, and then realize the high-sensitivity detection of the weak bubble echo of the ship wake under the strong reverberation background. It can replace the range-gating mode to a certain extent.

[0058] As Figures 5a to 5dAs shown in the figure, A in the figure is the transmitting field of view, and B is the receiving field of view. In order to achieve high-sensitivity detection for each receiving channel, the receiving field-of-view angle of each receiving channel is set to be small, so the receiving field-of-view range of each receiving channel is narrow. The optimal receiving distances corresponding to the receiving channels at different axle distances are different. By setting multiple receiving channels at different axle distances, the high-sensitivity detection of a single channel can be combined with the distributed reception of multiple channels to achieve the detection of ship wakes within a large dynamic range. At position 1, the laser echo is within the starting detection distance range and not within the receiving fields of view of the three receiving channels, so the receiver cannot receive the wake bubble echo signal; at position 2, only the near-field channel can receive the echo signal; at position 3, the near-field and mid-field channels can receive the echo signal; at position 4, all three channels can receive the echo signal. Figure 5d The center in it is the transmitting channel. From the inside to the outside of the transmitting channel, there are the far-field receiving channel, the mid-field receiving channel, and the far-field receiving channel in sequence. In order to be able to detect targets at a long distance, the receiving field-of-view angle of the receiving channel should decrease sequentially with the receiving channel, and the echo signal of the wake bubble received by it will be stronger. However, if the receiving field-of-view angle is too large, it will cause the receiving field-of-view coverage area to be too large. While receiving the wake bubble echo signal, too much water body signal and signals of other impurities will also be received. At the same time, if there are too many other types of signals, causing the saturation of the echo signal, the wake bubble echo signal will be submerged in other signals and it is impossible to judge whether there is a target through parameters such as amplitude.

[0059] On the basis of completing the multi-channel receiving system, an APD adaptive gain control system 7 is designed. The APD adaptive gain control system 7 is composed of an optical receiving structure, an optical fiber, an APD detector, and a filtering device. The light reflected by the target is focused on the optical fiber through a convex lens and a filtering device, and is coupled into the APD detector through the optical fiber.

[0060] An APD receiver applicable to ship wake detection is selected. In order to prevent APD saturation or the saturation of the amplifier circuit output, and at the same time improve the optical signal receiving ability within a large dynamic range, the APD receiving gain is optimized and controlled. Using the relationship between the dark current, photocurrent, and bias voltage of the APD, the photocurrent gain of the APD is adjusted by adjusting the magnitude of the APD bias voltage.

[0061] The improved circuit is as Figure 7 shown. By sending a setting command through the IIC interface, the contact position of the potentiometer can be adjusted, and then the output voltage can be changed. After design, the APD gain is divided into 256 levels.

[0062] The signal processing system 10 mainly consists of an amplification circuit, a conditioning circuit, a high-speed ADC acquisition circuit, and a processing circuit. The computer terminal sends a control signal to the laser to control the laser to emit light. After the laser is emitted and hits the target, it is reflected back to the receiving system and input into the APD detector through fiber optic coupling. The output current of the APD is converted and amplified by a transimpedance circuit and then sent to the conditioning circuit; the conditioning circuit performs single-ended to differential conversion on the signal and conducts analog filtering processing; the high-speed ADC acquisition circuit samples the signal at high speed and sends the signal to the processing circuit; the processing circuit processes the signal and outputs it to the oscilloscope; finally, it is transmitted to the computer terminal through a USB cable.

[0063] (1) Amplification circuit

[0064] The signal generated by the APD detector cannot be directly transmitted and needs to be amplified. The LTC6268-10 amplifier from ADI is selected. This amplifier has extremely low input reference current noise and voltage noise.

[0065] (2) Conditioning circuit

[0066] The conditioning circuit performs analog filtering processing on the amplified signal, converts the signal from single-ended to differential to match the input interface of the high-speed ADC, and obtains an electrical signal that meets the requirements of the subsequent circuit.

[0067] (3) High-speed ADC acquisition circuit

[0068] The A / D chip is the core of the signal acquisition circuit. The ADC uses ADS54J40, which has the advantages of low power consumption, high bandwidth, high signal-to-noise ratio, etc. It can provide a background noise of -158dBFS / hz and is suitable for ultra-high dynamic range applications requiring high instantaneous bandwidth, meeting the requirements of ship wake detection.

[0069] (4) Processing circuit

[0070] The processing circuit is the core component of the signal processing module of the detection system, which performs detection processing and filtering processing on the signal.

[0071] The large dynamic adaptive ship wake laser detection and tracking method provided by the embodiment of the present invention includes: the computer host 1 outputs a control instruction to control the laser 2 to output pulsed laser 3. After the output pulsed laser 3 is collimated, it is incident into the water environment. The laser beam composed of a large number of photons collides with the surface of the ship wake bubbles 4. A large number of photons are absorbed or scattered. The scattered photons are received by the multi-channel receiving system 5 and then transmitted to the APD adaptive gain control system 7 through the optical fiber 9. The output gain is adjusted according to the output waveform. Finally, the signal is output to the signal processing module for signal processing, transmitted to the oscilloscope 8 through a BNC cable for displaying an image, and finally the detection information is displayed. After continuous judgment, the ship wake is tracked.

[0072] II. Application Examples. To prove the creativity and technical value of the technical solution of the present invention, this part provides application examples of the technical solution of the claims in specific products or related technologies.

[0073] The technical solution of the present invention has been verified through tests that equivalently simulate the wake bubbles of ships under the background of complex indoor water bodies, and through tests in the outdoor lake environment, the environmental adaptability of the technical solution has been verified. It has solved the technical problem of extremely weak target detection in the underwater laser detection system under the background of strong reverberation for a long time, and can rapidly promote the engineering of the wake laser detection system. After the technical solution is transformed in the next step, a large-dynamic adaptive control and detection module in the underwater laser detection system can be formed, which can be applied to fields such as ship wake detection, underwater obstacle detection, fishing net detection, and underwater topographic and geomorphic exploration, reducing the implementation cost of the system, improving the environmental adaptability and reliability of the system, and having broad commercial value.

[0074] It should be noted that the embodiments of the present invention can be implemented through hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated designed hardware. Those of ordinary skill in the art can understand that the above devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips and transistors, or programmable logic devices such as field programmable gate arrays, and can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software, such as firmware.

[0075] III. Evidence of Related Effects of Embodiments. Some positive effects have been achieved during the research and development or use of the embodiments of the present invention, and there are indeed great advantages compared with the prior art. The following content will be described in combination with data, charts, etc. in the test process.

[0076] The technical solution of the present invention has been verified through tests that equivalently simulate the wake bubbles of ships under the background of complex indoor water bodies, and through tests in the outdoor lake environment, the feasibility and environmental adaptability of the technical solution have been verified. In the next step, in combination with different application scenarios, a large-dynamic adaptive control and detection module in the underwater laser detection system can be formed, which can be applied to fields such as ship wake detection, underwater obstacle detection, fishing net detection, and underwater topographic and geomorphic exploration.

[0077] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A large-dynamic adaptive laser detection and tracking device for ship wake, characterized in that The large-dynamic adaptive ship wake laser detection and tracking device includes: A laser emission system, which uses a semiconductor-pumped solid-state laser to design a beam expansion and collimation system according to the relationship between the beam angle, focal length, and light output aperture, and realizes controllable adjustment of the laser emission energy and repetition frequency; A multi-channel receiving system, which uses a multi-channel detection and receiving method to obtain photons scattered back after the laser beam collides with the surface of ship wake bubbles; An APD adaptive gain control system, which is connected to the multi-channel receiving system, and uses a digital potentiometer to realize controllable adjustment of the APD gain, and realizes the detection and reception of short pulses and large-dynamic laser echoes; A signal processing system, which is connected to the APD adaptive gain control system and is used to process signals; The laser emission system consists of a laser, a power supply, a beam expansion and collimation device, and an integrated processing and display control module. The laser is respectively connected to the power supply, the beam expansion and collimation system, and the integrated processing and display control module. The beam expansion and collimation system and the integrated processing and display control module are connected to the computer host; The beam expansion and collimation device realizes the function of electric focusing through the computer host, controls the change of the laser emission beam angle, and the integrated processing and display control module is used to adjust the laser switch and energy size parameters by controlling the current of the drive module and the TEC temperature control module; The multi-channel receiving system includes multiple receiving channels set at different axial distances, and the optimal receiving distances corresponding to the receiving channels at different axial distances are different; The APD adaptive gain control system includes an optical receiving structure, an optical fiber, an APD detector, and a filtering device. The light reflected by the target is focused on the optical fiber through a convex lens and a filtering device, and is coupled into the APD detector through the optical fiber; The APD detector uses the relationship between dark current, photocurrent, and bias voltage to adjust the photocurrent gain of the APD detector by adjusting the magnitude of the bias voltage of the APD detector.

2. The large-dynamic adaptive ship wake laser detection and tracking device according to claim 1, characterized in that The APD detector sends a setting command through the IIC interface, can adjust the contact position of the potentiometer, and then changes the output voltage. The APD gain is divided into 256 levels.

3. The large dynamic adaptive ship wake laser detection and tracking device according to claim 1, characterized in that The signal processing system consists of an amplification circuit, a conditioning circuit, a high-speed ADC acquisition circuit, and a processing circuit; The amplification circuit is used for the signal generated by the APD detector cannot be directly transmitted, and the signal needs to be amplified; The conditioning circuit is used for analog filtering of the amplified signal, and converts the signal from single-ended to differential to match the high-speed ADC input interface to obtain an electrical signal that meets the requirements of the subsequent circuit; The high-speed ADC acquisition circuit is used for signal acquisition; The processing circuit is used for signal detection processing and filtering processing.

4. A large dynamic adaptive ship wake laser detection and tracking method for implementing the large dynamic adaptive ship wake laser detection and tracking device according to any one of claims 1 to 3, characterized in that, The large-dynamic adaptive ship wake laser detection and tracking method includes: Step 1, the computer host outputs a control command to control the laser to output pulsed laser, and the output pulsed laser is collimated and then incident into the water environment; Step 2, the laser beam composed of a large number of photons collides with the surface of ship wake bubbles. A large number of photons are absorbed or scattered. The scattered photons are received by the multi-channel receiving system and transmitted to the APD adaptive gain control system through an optical fiber, and the output gain is adjusted according to the output waveform; Step 3: Finally, output the signal to the signal processing system for signal processing, transmit it to the oscilloscope via a BNC cable to display the image, and finally display the detection information. After continuous judgment, track the ship wake.

5. The large-dynamic adaptive ship wake laser detection and tracking method according to claim 4, characterized in that, In Step 1, the computer host outputs control instructions to control the laser to output pulsed laser. The computer host adjusts parameters such as the switch, energy level, and repetition frequency of the laser, and transmits the information to the integrated processing and display control module. The integrated processing and display control module adjusts parameters such as the switch and energy level of the laser by controlling the current of the drive module and the TEC temperature control module.

6. The large-dynamic adaptive ship wake laser detection and tracking method according to claim 5, characterized in that The drive circuit drives the internal emission of 808 nm pump light in the laser according to the information transmitted by the integrated processing and display control module. The pump light irradiates the laser working substance, and after a delay of 200 μs, a Q-switching signal is generated. The Q-switching module generates a high-voltage signal to control the generation of 1064 nm laser, which is frequency-doubled to 532 nm by OPO and emitted through the beam expander and collimator device.

Images