An underwater laser pulse time-domain broadening measurement system and method

Abstract

The application relates to an underwater laser pulse time domain expansion measurement system and method, wherein the measurement system comprises a receiving lens for directly aiming at a pulse laser to be measured and receiving a laser beam output by the pulse laser to be measured; a laser processing unit connected with the receiving lens in an optical path to perform collimation, attenuation and light filtering processing on the laser beam; a high-speed photoelectric detector connected with the laser processing unit in an optical path, used for collecting the processed laser beam and converting the laser pulse electrical signal W1; a data acquisition board electrically connected with the high-speed photoelectric detector, used for collecting the laser pulse electrical signal W1 and sending the laser pulse electrical signal W1 to an analysis processing unit; and the analysis processing unit receives the laser pulse electrical signal W1, calculates the pulse width of the laser pulse electrical signal W1, and calculates the time domain expansion of the laser beam according to a pulse expansion calculation method. The application realizes direct measurement of the time domain expansion of an underwater laser pulse, and improves the measurement accuracy.

Description

TECHNICAL FIELD

[0001] The application relates to the underwater laser measurement field, in particular to an underwater laser pulse time domain expansion measurement system and method. BACKGROUND

[0002] The ocean accounts for about 71% of the earth's surface and has great development potential. The observation and research of the ocean have important application prospects.

[0003] In the ocean photoelectric observation and detection equipment, pulsed laser is widely used, such as laser radar underwater target detection, underwater range-gated imaging, underwater LIBS spectrometer, etc. The pulse width of the laser has an important influence on the detection effect of these photoelectric equipment. For example, in the laser radar underwater target detection, the pulse width of the laser determines the radar ranging accuracy; in the underwater range-gated imaging, the pulse width of the laser determines the length of the gating time, and then determines the exposure time, which directly affects the imaging effect; in the underwater LIBS spectrometer, the pulse width of the laser determines the length of the light-matter interaction time, which affects the quantitative measurement accuracy of elements. Due to the multiple scattering effect of laser transmission in water, the laser pulse will be expanded under water, causing distortion, and then, in underwater optical communication, the expansion of the pulse may cause communication errors.

[0004] In order to study the time domain expansion of underwater pulsed laser, many research institutions have established simulation calculation models. For example, in the August 2014 issue of the Journal of Changchun University of Science and Technology, Vol. 37, No. 4, published by Changchun University of Science and Technology, Yin Hang, Liu Zhi, etc. disclosed a simulation analysis of underwater laser pulse transmission time domain expansion. Through the Fournier-Forand and Henyey-Greenstein scattering phase function, combined with the small-angle approximation method, the laser pulse waveform expression is derived, and the transmission waveform of laser pulse signals with different widths is simulated. In the January 2009 issue of the Chinese Journal of Lasers, Vol. 36, No. 1, published by the Naval University of Engineering, Zhou Yamin, Liu Qizhong, etc. disclosed a simulation calculation method for underwater transmission time domain expansion of laser pulse. This method applies the classical electron scattering theory to the study of photon scattering. Starting from the L.B.Stotts model, through selecting a suitable water scattering phase function, the laser pulse waveform expression is derived, and the pulse width after transmission for a certain distance under certain water quality conditions is simulated. In addition, in the November 2010 issue of the Acta Optica Sinica, Vol. 30, No. 11, Huang Youwei, Wang Xia, etc. of Beijing University of Technology analyzed the timing relationship between underwater pulse transmission and detector gating reception, established a relatively complete range-gated timing model, and designed a special model verification experiment based on the established underwater pulsed laser range-gated experimental platform.

[0005] As described above, there are few measurements of underwater pulse laser broadening in the related art, mainly some theoretical calculations and model simulations. Although the method of measuring pulse broadening by distance gating imaging proposed by Beijing Institute of Technology realizes intuitive measurement, it has the problem of lacking accurate measurement of pulse waveform, quantitative analysis and research difficulties. In addition, the method of detecting and receiving backscattering has many interference factors, such as multiple backscattering of transmission path, different target reflectivity, and too large field of view angle of receiving lens.

[0006] At present, there is no effective solution for measuring underwater pulse laser broadening in the related art. SUMMARY

[0007] The embodiment of the present application provides a kind of underwater laser pulse time domain broadening measurement system and method, realize the time domain broadening of direct measurement underwater laser pulse, improve measurement accuracy, and provide the basis for the theoretical research and model research of laser pulse broadening caused by underwater scattering effect.

[0008] In the first aspect, the embodiment of the present application provides a kind of underwater laser pulse time domain broadening measurement system, comprising:

[0009] Receiving lens, for directly aiming at the pulse laser to be measured and receiving the laser beam output by the pulse laser to be measured, specifically, the receiving lens directly receives the forward transmission light of the pulse laser to be measured to avoid the interference of other factors;

[0010] Laser processing unit, optically connected with the receiving lens, for collimating, attenuating and filtering the laser beam;

[0011] High-speed photoelectric detector, optically connected with the laser processing unit, for collecting the processed laser beam and converting to obtain laser pulse electrical signal W1;

[0012] Data acquisition board, electrically connected with the high-speed photoelectric detector, for collecting the laser pulse electrical signal W1 and sending to an analysis processing unit;The analysis processing unit is used for receiving the laser pulse electrical signal W1 and calculating the pulse width width W 11 , W 12 ……, W 1n Then, the time domain broadening of the laser beam is calculated according to the pulse broadening calculation method. Specifically, the analysis processing unit is a computer device, and the data acquisition board is connected with the analysis processing unit through water-tight cable communication. Optionally, the pulse width width W 11 , W 12 ……, W 1nThe laser pulse electrical signal can be calculated by half-wave width, 10% Pmax width or 20% Pmax width, etc., which is not limited herein, wherein Pmax is used to represent the waveform height value of the laser pulse electrical signal.

[0013] In some embodiments, the laser processing unit comprises a diaphragm, a lens, an adjustable attenuating sheet and a narrow-band filter connected in sequence, so as to limit the field of view by the diaphragm, and to collimate, attenuate and filter the laser beam by the lens, the adjustable attenuating sheet and the narrow-band filter.

[0014] In some embodiments, the data acquisition board is further electrically connected with a preamplification circuit between the data acquisition board and the high-speed photoelectric detector, for amplifying the laser pulse electrical signal.

[0015] In some embodiments, the output end of the to-be-measured pulse laser is provided with a collimating lens, and the receiving lens adopts a narrow-field lens, so as to avoid stray light interference.

[0016] In some embodiments, the response speed of the high-speed photoelectric detector, the preamplification circuit and the data acquisition board is ≥1 GHz, and the dynamic range of the data acquisition board is ≥14 bits.

[0017] In some embodiments, the high-speed photoelectric detector is a photoelectric detector based on a photomultiplier tube (PMT) or an avalanche photoelectric detector (APD).

[0018] In some embodiments, the analysis processing unit is pre-stored with laser pulse electrical signals W0 and their pulse widths W0, W1, …, Wn transmitted in an air environment collected by the measurement system. 01 02 0n 01 02 0n The pulse widths W0, W1, …, Wn are used for the analysis processing unit to compare and analyze the pulse widths W0, W1, …, Wn and the pulse widths W0, W1, …, Wn, and to calculate the time-domain broadening. 01 02 0n 11 12 1n

[0019] In some embodiments, the pulse broadening calculation method comprises an average value pulse broadening calculation method and a root mean square pulse broadening calculation method.

[0020] ​​​​​​​​​​​Based on the above structure, this application uses a high-speed photodetector (PMT or APD) combined with a data acquisition board to acquire the laser beam signal. After photoelectric conversion by the high-speed photodetector, the signal is amplified by the preamplifier circuit and then acquired at high speed by the data acquisition board. Finally, the analysis and processing unit analyzes and measures the laser pulse signal after it has passed through a certain distance of seawater. By comparing the measured value with the value in the air, the time domain broadening is obtained.

[0021] Secondly, embodiments of this application provide an underwater laser pulse time-domain stretching measurement method, based on the underwater laser pulse time-domain stretching measurement system described in the first aspect above, including:

[0022] The steps for acquiring the laser pulse width in an air environment are as follows: The measurement system is installed and adjusted along the optical axis of the laser under test in an air environment, and a laser beam is emitted. The measurement system acquires and calculates the laser pulse electrical signal W0 and its pulse width W transmitted in the air environment. 01 W 02 ... W 0n ;

[0023] The underwater environment laser pulse width acquisition step involves moving the laser under test and the measurement system to the underwater environment, and using the measurement system to acquire and calculate the laser pulse electrical signal W1 and its pulse width W transmitted in the underwater environment. 11 W 12 ... W 1n ;

[0024] The laser pulse temporal broadening acquisition step involves calculating the pulse width W based on the pulse broadening calculation method. 01 W 02 ... W 0n and the pulse width W 11 W 12 ... W 1n The time-domain broadening is obtained by calculation.

[0025] In some embodiments, the step of obtaining the air environment laser pulse width further includes:

[0026] The attenuator adjustment steps involve adjusting the adjustable attenuator by gradually reducing the attenuation factor. When the laser pulse signal is saturated, the attenuation factor is adjusted to make the laser pulse signal intensity 90% to 95% of the saturation intensity, and the adjustable attenuator is then fixed.

[0027] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0029] Figure 1 is a structural block diagram of an underwater laser pulse time domain broadening measurement system according to an embodiment of the application;

[0030] Figure 2 is a half-wave width waveform schematic diagram of a laser pulse according to an embodiment of the application;

[0031] Figure 3 is a flow chart of an underwater laser pulse time domain broadening measurement method according to an embodiment of the application.

[0032] In the drawings:

[0033] 11, receiving lens;

[0034] 12, laser processing unit;

[0035] 13, high-speed photoelectric detector;

[0036] 14, preamplifier circuit;

[0037] 15, data acquisition board;

[0038] 16, analysis processing unit;

[0039] 21, pulse laser to be measured;

[0040] 22, collimating lens;

[0041] 121, diaphragm;

[0042] 122, lens;

[0043] 123, adjustable attenuator;

[0044] 124, narrow-band filter. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the application clearer, the application is described and explained below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application. Based on the embodiments provided in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the application.

[0046] It is apparent that the drawings in the following description merely show some examples or embodiments of the present application, and for those skilled in the art, the present application can be applied to other similar situations without creative labor based on these drawings. In addition, it can be understood that although the efforts made in this development process can be complex and lengthy, some design, manufacture or production changes based on the technical content disclosed in the present application are only routine technical means for those skilled in the art related to the disclosure of the present application, and should not be understood as insufficient disclosure of the present application.

[0047] In the present application, the phrase "embodiment" means that the specific features, structures or characteristics described in conjunction with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments without conflict.

[0048] Unless otherwise defined, the technical terms or scientific terms involved in the present application should be understood as the usual meaning understood by those skilled in the art in the technical field to which the present application belongs. The terms "one", "a", "an", "the", and the like similar words involved in the present application do not represent quantity limitation, but can represent singular or plural. The terms "include", "contain", "have", and any variations thereof involved in the present application are intended to cover non-exclusive inclusion; for example, a process, method, system, product or device including a series of steps or modules (units) is not limited to the listed steps or units, but can also include steps or units not listed, or can also include other steps or units inherent to these processes, methods, products or devices. The terms "connected", "connected", "coupled" and the like similar words involved in the present application are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The term "multiple" refers to two or more. The association between the associated objects is described by the term "and / or", which means that there can be three relationships, for example, "A and / or B" can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects. The terms "first", "second", "third", and the like involved in the present application are merely to distinguish similar objects, and do not represent a specific order for the objects.

[0049] The embodiment of the present application provides a water laser pulse time domain expansion measurement system, Figure 1 is a structural block diagram of the water laser pulse time domain expansion measurement system according to the embodiment of the present application, referring to Figure 1As shown, the measurement system comprises a receiving lens 11, a laser processing unit 12, a high-speed photoelectric detector 13, a data acquisition board 15 and the like. Those skilled in the art can understand that Figure 1 The user terminal structure shown in the figure does not constitute a limitation on the user terminal, and can include more or fewer components than shown, or combine certain components, or different component arrangements.

[0050] The following will be described in detail Figure 1 The various components of the measurement system will be described in detail:

[0051] The receiving lens 11 is used to directly aim at the pulsed laser to be measured 21 and receive the laser beam output by the pulsed laser to be measured 21. In the figure, the distance between the receiving lens 11 and the output end of the laser to be measured 21 is L. Specifically, the receiving lens 11 directly receives the forward transmission light of the pulsed laser to be measured, which can avoid interference from other factors.

[0052] The laser processing unit 12 is optically connected to the receiving lens 11. The laser processing unit 12 is used for collimation, attenuation and filtering of the laser beam. Specifically, the laser processing unit 12 comprises a diaphragm 121, a lens 122, an adjustable attenuation sheet 123 and a narrow-band filter 124 connected in sequence, so as to limit the field of view through the diaphragm 121, and to collimate, attenuate and filter the laser beam through the lens 122, the adjustable attenuation sheet 123 and the narrow-band filter 124.

[0053] The high-speed photoelectric detector 13 is optically connected to the laser processing unit 12, and is used to collect the processed laser beam and convert it into a laser pulse electrical signal W1. Optionally, the high-speed photoelectric detector 13 is a photoelectric detector based on a photomultiplier PMT or an avalanche photodetector APD. Based on this, the high-speed photoelectric detector 13 is used as a single-point photoelectric detector to directly detect the pulse waveform of the laser beam, so as to realize high-speed collection of the laser pulse electrical signal, and compared with the existing measurement by imaging, the response speed is faster, and the accuracy of waveform analysis is improved.

[0054] The data acquisition board 15 is electrically connected to the high-speed photoelectric detector 13 through a preamplifier circuit 14. The preamplifier circuit 14 is used to amplify the laser pulse electrical signal W1. The data acquisition board 15 is used to collect the laser pulse electrical signal W1 and send it to an analysis processing unit 16. The analysis processing unit 16 is used to receive the laser pulse electrical signal W1 and calculate the pulse width of the laser pulse electrical signal W1, and then calculate the time-domain broadening of the laser beam according to a pulse broadening calculation method. Optionally, the pulse width can be calculated according to the half-wave width (such as Figure 2 As shown, the 10% P max width or the 20% P max width, etc., which are not limited here, wherein P maxThis is used to represent the waveform height value of the laser pulse electrical signal. The high-speed photodetector 13, preamplifier circuit 14, and data acquisition board 15 have a response speed ≥ 1 GHz, and the dynamic range of the data acquisition board 15 is ≥ 14 bits. The analysis and processing unit 16 pre-stores the laser pulse electrical signal W0 and its pulse width W transmitted in an air environment, acquired using the measurement system. 01 W 02 ... W 0n Pulse width W 01 W 02 ... W 0n The pulse width W is used for comparative analysis in the analysis and processing unit 16. 01 W 02 ... W 0n and pulse width W 11 W 12 ... W 1n The time-domain pulse broadening is then calculated. Specifically, pulse broadening calculation methods include the average pulse broadening calculation method and the root mean square pulse broadening calculation method.

[0055] Existing methods generally employ a backward measurement approach. Under limited measurement distances, increasing the receiving field of view is necessary to reduce the blind zone. This allows a large amount of stray light from other angles to enter the receiving lens 11, resulting in inaccurate measurement results representing the forward broadening of long-distance transmission. Therefore, in this embodiment, a collimating lens 22 is provided at the output end of the pulsed laser under test 21, and a narrow field-of-view lens is used in the receiving lens 11 to avoid stray light interference. The output end of the pulsed laser under test 21 is collimated using the collimating lens 22, and the narrow field-of-view lens is directly aligned with the forward transmission light of the receiving pulsed laser, achieving complete reception of the laser beam under test while greatly minimizing stray light interference, resulting in more accurate measurement of the broadening.

[0056] Specifically, the analysis and processing unit 16 is a computer device, and the data acquisition board 15 is communicatively connected to the analysis and processing unit 16 via a watertight cable. The computer device may include a processor and a memory storing computer program instructions. Specifically, the processor may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application. The memory may include a large-capacity memory for data or instructions. The memory can be used to store or cache various data files that need to be processed and / or communicated, as well as possible computer program instructions executed by the processor. The processor implements any of the pulse broadening calculation methods in the above embodiments by reading and executing the computer program instructions stored in the memory.

[0057] Based on the above structure, this application uses a high-speed photodetector 13 (PMT or APD) combined with a data acquisition board 15 to acquire the laser beam signal. After photoelectric conversion by the high-speed photodetector 13, the signal is amplified by the preamplifier circuit 14 and then acquired at high speed by the data acquisition board 15. Finally, the analysis and processing unit 16 performs analysis and fine measurement of the laser pulse signal after passing through a certain distance of seawater. By comparing it with the air laser pulse signal in the air and the pulse width of the air environment, time-domain broadening is obtained.

[0058] Based on the underwater laser pulse time-domain stretching measurement system of the above embodiments and preferred embodiments, this application also provides an underwater laser pulse time-domain stretching measurement method, which will not be repeated here as has been described before. Figure 3 This is a flowchart of an underwater laser pulse time-domain stretching measurement method according to an embodiment of this application, as shown below. Figure 3 As shown, the process includes the following steps:

[0059] Step S1 for acquiring the laser pulse width in an air environment: A measurement system is installed and adjusted along the optical axis of the laser under test 21 in an air environment, and an output laser beam is emitted. The measurement system acquires and calculates the laser pulse electrical signal W0 and its pulse width W transmitted in the air environment. 01 W 02 ... W 0n The step S1 for obtaining the laser pulse width in the air environment further includes:

[0060] In the attenuator adjustment step S101, the adjustable attenuator 123 is adjusted by gradually decreasing the attenuation factor. Once the laser pulse signal is saturated, the attenuation factor is adjusted to make the laser pulse signal intensity 90%–95% of the saturation intensity, and the adjustable attenuator 123 is fixed. Specifically, the adjustable attenuator 123 can be adjusted using a stepping attenuation disk or other electric adjustment methods. It should be noted that this attenuation factor is also the attenuation factor used in the underwater environment laser pulse width acquisition step to ensure the same attenuation factor measurement in air and underwater environments, avoiding errors caused by the attenuator.

[0061] In step S2, the laser pulse width acquisition in the underwater environment involves moving the laser under test and the measurement system to the underwater environment, and using the measurement system to acquire and calculate the laser pulse electrical signal W1 and its pulse width W transmitted in the underwater environment. 11 W 12 ... W 1n ;

[0062] Step S3, obtaining laser pulse temporal broadening, involves calculating the pulse width W based on the pulse broadening calculation method. 01 W02 ... W 0n and pulse width W 11 W 12 ... W 1n Calculations are performed to obtain the time-domain broadening.

[0063] The pulse broadening calculation method of this application embodiment will be described and explained below with examples.

[0064] Taking half-width as an example, the pulse width measured n times in air is W. 01 W 02 ... W 0n The pulse width measured n times underwater is W. 11 W 12 ... W 1n .

[0065] If the average pulse broadening calculation method is used, the pulse broadening can be calculated based on the following calculation model:

[0066]

[0067] in, pulse width W 11 W 12 ... W 1n The average value, pulse width W 01 W 02 ... W 0n The average value.

[0068] If the root mean square pulse broadening calculation method is used, the pulse broadening can be calculated based on the following calculation model:

[0069] ΔW=W 1RMS -W 0RMS

[0070] Among them, W 1RMS pulse width W 11 W 12 ... W 1n The root mean square value, W 0RMS pulse width W 01 W 02 ... W 0n The root mean square value.

[0071] Through the above steps, the embodiments of this application can directly obtain time-domain broadening based on the pulse width of the air environment and the pulse width of the air environment obtained by the measurement system. Compared with the existing measurement by imaging method, the response speed is faster, effectively solving the difficulties of accurate measurement and quantitative analysis of pulse waveforms, and solving the interference factors of backscattering, thus improving the accuracy of waveform analysis.

[0072] It should be noted that the steps shown in the above process or in the flowchart of the accompanying figures can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An underwater laser pulse time-domain stretching measurement system, characterized in that, include: A receiving lens is used to directly align with the pulsed laser under test and receive the laser beam output by the pulsed laser under test. The output end of the pulsed laser under test is provided with a collimating lens. The receiving lens is a narrow field of view lens. The output end of the pulsed laser under test uses the collimating lens to collimate the laser beam. The narrow field of view lens is used to directly align with the forward transmission light of the receiving pulsed laser to achieve complete reception of the laser beam. A laser processing unit is optically connected to the receiving lens. The laser processing unit is used to collimate, attenuate, and filter the laser beam. The laser processing unit includes an aperture, a lens, an adjustable attenuator, and a narrowband filter connected in sequence by optical path. A high-speed photodetector, with an optical path connected to the laser processing unit, is used to collect the processed laser beam and convert it into a laser pulse electrical signal W1. A data acquisition board, electrically connected to the high-speed photodetector, is used to acquire the laser pulse electrical signal W1 and send it to an analysis and processing unit. The analysis and processing unit receives the laser pulse electrical signal W1, calculates its pulse width, and then calculates the time-domain broadening of the laser beam using a pulse broadening calculation method. The analysis and processing unit pre-stores laser pulse electrical signals W0 and their pulse widths W1 acquired by the measurement system and transmitted in an air environment. 01 W 02 ... W 0n The pulse width W 01 W 02 ... W 0n The analysis and processing unit is used to compare and analyze the pulse width W. 01 W 02 ... W 0n and the pulse width W 11 W 12 ... W 1n The time-domain broadening is then calculated.

2. The underwater laser pulse time-domain stretching measurement system according to claim 1, characterized in that, A preamplifier circuit is also electrically connected between the data acquisition board and the high-speed photodetector to amplify the laser pulse electrical signal.

3. The underwater laser pulse time-domain stretching measurement system according to claim 2, characterized in that, The high-speed photodetector, preamplifier circuit, and data acquisition board have a response speed of ≥1GHz, and the dynamic range of the data acquisition board is ≥14 bits.

4. The underwater laser pulse time-domain stretching measurement system according to claim 2, characterized in that, The high-speed photodetector is a photodetector based on a photomultiplier tube (PMT) or an avalanche photodetector (APD).

5. The underwater laser pulse time-domain stretching measurement system according to claim 1, characterized in that, The pulse broadening calculation method includes the average pulse broadening calculation method and the root mean square pulse broadening calculation method.

6. A method for measuring the time-domain broadening of underwater laser pulses, based on the underwater laser pulse time-domain broadening measurement system as described in any one of claims 1 to 5, characterized in that, include: The steps for acquiring the laser pulse width in an air environment are as follows: The measurement system is installed and adjusted along the optical axis of the laser under test in an air environment, and a laser beam is emitted. The measurement system acquires and calculates the laser pulse electrical signal W0 and its pulse width W transmitted in the air environment. 01 W 02 ... W 0n ; The underwater environment laser pulse width acquisition step involves moving the laser under test and the measurement system to the underwater environment, and using the measurement system to acquire and calculate the laser pulse electrical signal W1 and its pulse width W transmitted in the underwater environment. 11 W 12 ... W 1n ; The laser pulse temporal broadening acquisition step involves calculating the pulse width W based on the pulse broadening calculation method. 01 W 02 ... W 0n and the pulse width W 11 W 12 ... W 1n The time-domain broadening is obtained by calculation.

7. The underwater laser pulse time-domain stretching measurement method according to claim 6, characterized in that, The step of obtaining the laser pulse width in the air environment also includes: The attenuator adjustment steps involve adjusting the adjustable attenuator by gradually reducing the attenuation factor. When the laser pulse signal is saturated, the attenuation factor is adjusted to make the laser pulse signal intensity 90%~95% of the saturation intensity, and the adjustable attenuator is then fixed.

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