Method and system for rapidly predicting detonation velocity of laser-loaded single-particle energetic material

Abstract

The invention provides a laser-loaded single-particle energetic material detonation velocity rapid prediction method and system, pulse laser is used for loading a single-particle energetic material to generate shock waves, an enhanced sCMOS camera is used for collecting shock wave images, shock wave position information in the shock wave images is used for calculating shock wave characteristic velocity, and the detonation velocity of the single-particle energetic material is predicted according to the shock wave characteristic velocity. A linear relation model is established for the shock wave characteristic speed and the known macroscopic detonation velocity through partial least square regression, and rapid prediction of the detonation velocity of the energetic material is achieved; according to the invention, the consumed sample amount is extremely small, the interaction among particles is eliminated, the safety is high, the laser pulse can only excite one single-particle energetic material each time, and the test can be completed only by using the particle-level energetic material; the method is of great significance in improving the testing safety of the energetic material and testing the performance of the energetic material with ultra-small dose and even multiple single-particle magnitudes.

Description

Technical Field

[0001] The invention belongs to the technical field of detonation performance detection of energetic materials, and in particular relates to a method and system for quickly predicting the detonation velocity of a single-particle energetic material loaded by laser. Background Art

[0002] Energetic materials are important energy sources in weapon systems, and the rapid detection of their explosion performance parameters directly affects the research and development of energetic materials. Detonation velocity, as a key parameter to measure the speed at which energetic materials release energy, is directly related to the intensity and effect of the explosion. Testing detonation performance is crucial for guiding the research and development of new energetic materials and evaluating their safety during storage and transportation.

[0003] Traditional detonation performance testing is constrained by charge density and critical diameter, consumes large amounts of charge and is highly dangerous. New materials are constantly emerging, but due to limited production, they are unable to meet critical diameter and density requirements, resulting in the inability to detect key performance indicators.

[0004] In recent years, the detection technology based on the particle group micro-explosion method under laser loading is expected to solve this problem, but this method inevitably introduces factors such as particle size differences, inter-particle interface effects, and different ablation volumes and thermal conductivity in the detection, resulting in insufficient detection reliability. Some new energetic materials are initially synthesized with only a few or a single particle, which cannot meet the milligram-level minimum detection dose requirement of the particle group micro-explosion detection method. Summary of the invention

[0005] In order to solve the problems that traditional detonation velocity test methods consume a large amount of medicine, the experimental operation is complicated and the risk is high, the particle size difference and interface effect of the particle group micro-explosion method lead to insufficient reliability, and some new energetic materials with only a few particles cannot be tested for detonation velocity, the present invention provides a method and system for quickly predicting the detonation velocity of a single-particle energetic material loaded by laser, by shooting the shock wave image generated by a single particle of the laser loaded energetic material, extracting the shock wave position information and calculating the shock wave characteristic velocity matrix, and establishing a model through an intelligent algorithm to realize the prediction of the detonation velocity.

[0006] A laser-loaded single-particle energetic material detonation velocity rapid prediction system, comprising a timing controller, a shock wave image acquisition subsystem, an optical processing subsystem, and a single-particle energetic material selection subsystem and a LIBS subsystem for partially sharing the same optical path;

[0007] The single-particle energetic material selection subsystem is used to select an imaging position for placing a single-particle energetic material, wherein the imaging position satisfies: the laser focusing position of the LIBS subsystem is at the same height as the position where the image is clearest in the single-particle energetic material selection subsystem, and the laser focusing spot of the LIBS subsystem at the imaging position is smaller than the area of ​​the single-particle energetic material;

[0008] The LIBS subsystem is used to emit laser light to excite a single particle of energetic material located at an imaging position;

[0009] The timing controller is used to control the triggering time of the LIBS subsystem and the shock wave image acquisition subsystem, so that the LIBS subsystem is triggered to emit laser light first, and the shock wave image acquisition subsystem acquires shock wave images of the single energetic particle after being excited at different time delays, and the triggering time of the shock wave image acquisition subsystem is later than the triggering time of the LIBS system, and the difference between the triggering times of the two is the delay, until the shock wave images of all the delay times of the different types of single energetic particles are acquired;

[0010] The optical processing subsystem is used to establish a linear prediction model of the shock wave characteristic velocity and detonation velocity of a single particle of energetic material according to different delayed shock wave images.

[0011] Further, the single particle energetic material selection subsystem includes a first visible light source 8, a first dichroic mirror 4, a second dichroic mirror 5, a microscope objective 6 and a CMOS camera 9;

[0012] The first visible light source 8 is used to provide an illumination and observation light source for imaging the sample surface, wherein the illumination and observation light source is reflected by the first dichroic mirror 4, transmitted through the second dichroic mirror 5 and the microscope objective lens 6 to illuminate the sample surface placed on the sample stage 7, and the illumination and observation light source illuminates the sample surface to form a sample optical signal, which is sequentially transmitted through the microscope objective lens 6 and reflected by the second dichroic mirror 5 to enter the CMOS camera 9, and the CMOS camera 9 is used to convert the sample optical signal into a sample image.

[0013] Further, the LIBS subsystem includes a pulsed laser 1, a reflector 2, a concave lens 3-1, a plano-convex lens 3-2, a first dichroic mirror 4 for reflection, a second dichroic mirror 5 and a microscope objective 6;

[0014] The pulse laser 1 is used to provide a pulse laser light source, wherein the pulse laser light source is reflected by the reflector 2 in sequence, transmitted by the concave lens 3-1 and the plano-convex lens 3-2, and a divergent pulse laser is obtained; the divergent pulse laser is transmitted by the first dichroic mirror 4 and the second dichroic mirror 5, and finally the divergent pulse laser is focused by the microscope objective lens 6, and finally focused on a single particle of energetic material on the sample stage 7;

[0015] Among them, the distances between the concave lens 3-1 and the plano-convex lens 3-2 are different, and the divergence angles of the divergent pulse lasers obtained are different. With different divergence angles, the heights of the laser focusing positions obtained when the microscope objective 6 focuses the divergent pulse lasers are different. The smaller the distance, the larger the divergence angle, and the lower the height of the laser focusing position. Conversely, the larger the distance, the smaller the divergence angle, and the higher the height of the laser focusing position.

[0016] Furthermore, the imaging position is obtained by:

[0017] Changing the distance between the sample stage 7 and the microscope objective 6 until the sample image in the CMOS camera 9 is clearest;

[0018] The distance between the concave lens 3-1 and the plano-convex lens 3-2 is adjusted to change the height of the laser focus position obtained when the microscope objective lens 6 focuses the divergent pulsed laser, until the laser focus position is at the same height as the position where the sample image in the CMOS camera 9 is clearest.

[0019] Furthermore, after obtaining the imaging position, the imaging position is marked, and the marking method is:

[0020] A marker is placed on the sample stage, and the pulse laser 1 sends a pulse laser to generate an ablation pit on the marker. The three-dimensional coordinates of the ablation pit are marked as the three-dimensional coordinates of the imaging position.

[0021] Furthermore, the shock wave image acquisition subsystem includes a second visible light source 10, a first convex lens 11, a slit 12, a second convex lens 13, a third convex lens 14, an aperture 15, a filter 16, a lens 17 and an enhanced sCMOS camera 18; meanwhile, the single particle of energetic material is located between the second convex lens 13 and the third convex lens 14, and the area where the plasma and shock wave generated after the single particle of energetic material is excited is located is the disturbance area;

[0022] The second visible light source 10 is used to provide a background light source for the shock wave disturbance generated after the single particle of energetic material is excited, wherein the background light source passes through the first convex lens 11, the slit 12, and the second convex lens 13 in sequence to form parallel light, and the parallel light is deflected after passing through the disturbance area. The deflected light passes through the third convex lens 14, the aperture 15, the filter 16, and the lens 17 in sequence and is incident on the enhanced sCMOS camera 18, forming a shock wave image in the enhanced sCMOS camera 18.

[0023] Furthermore, the delay of the shock wave image acquisition subsystem is 0.5μs, 1.0μs, 1.5μs, 2.0μs, 2.5μs, 3.0μs, 4.0μs, 5.0μs, 6.0μs, 7.0μs, 8.0μs, 9.0μs, 10.0μs, 15.0μs, and 20.0μs after the single particle of energetic material is excited.

[0024] A method for rapidly predicting the detonation velocity of a laser-loaded single-particle energetic material based on a laser-loaded single-particle energetic material detonation velocity rapid prediction system comprises the following steps:

[0025] S1: For each energetic material, two sets of shock wave images collected at different time delays after being excited are obtained, among which there are 15 different time delays;

[0026] S2: For each energetic material, obtain the shock wave characteristic velocity vector of each group according to the two groups of shock wave images, wherein the method for obtaining the shock wave characteristic velocity vector of any group of shock wave images of each energetic material is specifically as follows:

[0027] S21: obtaining shock wave front position information in the shock wave images of the current group with different delays for each energetic material;

[0028] S22: Obtain the average value of the shock wave radius corresponding to each delay respectively, wherein the method for obtaining the average value of the shock wave radius of the nth delay is:

[0029] The major axis radius is obtained by performing an ellipse fitting on the front position information of the nth delayed shock wave Minor axis radius And the major axis radius Corresponding to the lateral propagation radius, the minor axis radius Corresponding to the longitudinal propagation radius, and the major axis radius With minor axis radius The average radius of the shock wave is recorded as

[0030] S23: Obtain the average propagation speed of the shock wave corresponding to each two delays, wherein the average propagation speed of the shock wave between the nth delay and the n+1th delay is The calculation method is:

[0031]

[0032] in, is the average radius of the n+1th delay, t n+1 is the n+1th delay, t n is the nth delay;

[0033] S24: Obtain the average transverse velocity of the shock wave and the average longitudinal propagation velocity of the shock wave corresponding to each two delays, wherein the average transverse velocity of the shock wave between the nth delay and the n+1th delay is and the average longitudinal velocity of the shock wave The calculation method is:

[0034]

[0035] in, is the major axis radius corresponding to the nth delay, is the minor axis radius corresponding to the nth delay;

[0036] S25: Obtain the shock wave propagation distance fitting curve corresponding to the current group of shock wave images through the Dewey model, and then derive the shock wave propagation distance fitting curve at 15 delays to obtain the shock wave propagation fitting speed v of 15 delays n ;

[0037] S26: Constructing the shock wave characteristic velocity vector I of the current group of shock wave images m as follows:

[0038]

[0039] Wherein, v0 is the average propagation velocity of the shock wave with a delay of 0.5 μs, which is obtained by dividing the radius of the shock wave with a delay of 1 μs by 1 μs; m = 1, 2;

[0040] S3: Construct the shock wave characteristic velocity matrix q of the current energetic material by using the shock wave characteristic velocity vectors corresponding to the two different delays:

[0041]

[0042] S4: The shock wave characteristic velocity vectors I1 and I2 corresponding to each energetic material are averaged to obtain the final shock wave characteristic velocity matrix Q for each energetic material. k , k is the label of each energetic material, and the shock wave characteristic velocity matrix of all energetic materials is Q:

[0043]

[0044] S5: The shock wave characteristic velocity matrix Q is fitted by an intelligent algorithm based on partial least squares regression to obtain a linear prediction model for the shock wave characteristic velocity and detonation velocity of a single particle of energetic material.

[0045] Furthermore, the method for obtaining the shock wave front of any shock wave image is as follows:

[0046] Calculate the gradient value matrix of the shock wave image along the horizontal positive direction, the horizontal negative direction, the vertical negative direction, and the vertical positive direction to obtain the gradient maps in four directions;

[0047] The gradient images in each direction are smoothed and filtered respectively, and then based on the Laida criterion, the gradient intensity threshold is used to directly remove the significant noise points in the gradient images after smoothing filtering whose gradient intensity fluctuation is greater than the set multiple standard deviation, and the smoothed gradient images in each direction are obtained;

[0048] The smooth gradient images in each direction are processed by opening and closing operations respectively, wherein the opening operation is used to eliminate the secondary noise points whose connectivity does not meet the set requirements, and the closing operation is used to eliminate the pulse noise points inside the shock wave. Then, the smooth gradients processed by the opening and closing operations are subjected to denoising by the median filter to obtain the primary denoising images in each direction after the noise points are removed;

[0049] The first denoised image corresponding to the positive and negative gradient images in the horizontal direction and the first denoised image corresponding to the positive and negative gradient images in the vertical direction are spliced ​​respectively to obtain a spliced ​​gradient image, wherein the splitting line of the horizontal splicing is determined by the estimated value of the laser incident line position, and the splitting line of the vertical splicing is determined by the estimated value of the height position of the sample cover glass surface;

[0050] Calculate the gradient value matrix of the spliced ​​gradient image along the horizontal positive direction, horizontal negative direction, vertical negative direction, and vertical positive direction to obtain the secondary gradient image in four directions;

[0051] The secondary gradient images in four directions are spliced ​​to obtain a secondary spliced ​​gradient image;

[0052] The secondary splicing gradient image is subjected to secondary denoising by means of a random sampling consistency algorithm, and the secondary gradient image after secondary denoising is used as the final shock wave front.

[0053] Beneficial effects:

[0054] 1. The present invention provides a laser-loaded single-particle energetic material detonation velocity rapid prediction system, which utilizes pulsed laser to load single-particle energetic material to generate shock wave, utilizes enhanced sCMOS camera to collect shock wave image, calculates shock wave characteristic velocity through shock wave position information in shock wave image, establishes linear relationship model between shock wave characteristic velocity and known macroscopic detonation velocity through partial least squares regression, and realizes rapid prediction of detonation velocity of energetic material; The present invention consumes very little sample amount, eliminates interaction between particles, has high safety, can realize that only one single-particle energetic material is excited each time laser pulse, and only energetic material of particle level is required to complete test, which is of great significance to improving safety of energetic material test and performing performance test on energetic material of ultra-small charge amount or even several single-particle level.

[0055] 2. The present invention provides a method for rapidly predicting the detonation velocity of a single-particle energetic material loaded with laser, and provides a detailed modeling process of a linear prediction model of the characteristic velocity of the shock wave and the detonation velocity of a single-particle energetic material, which can realize rapid prediction of the detonation velocity of the energetic material, and is of great significance for improving the safety of energetic material testing and for performing performance testing on energetic materials of ultra-small charge or even several single-particle levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1A schematic diagram of a laser-loaded single-particle energetic material detonation velocity rapid prediction system provided by the present invention;

[0057] 1—pulse laser; 2—reflector; 3-1—concave lens, 3-2—plano-convex lens, 3—beam expander; 4—first dichroic mirror; 5—second dichroic mirror; 6—microscope objective; 7—sample stage, 8—first visible light source, 9—CMOS camera, 10—second visible light source, 11—first convex lens, 12—slit, 13—second convex lens, 14—third convex lens, 15—aperture, 16—filter, 17—lens, 18—enhanced sCMOS camera, 19—timing controller. DETAILED DESCRIPTION

[0058] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0059] A laser-loaded single-particle energetic material detonation velocity rapid prediction system, comprising a timing controller of model DG535, a shock wave image acquisition subsystem, an optical processing subsystem, and a single-particle energetic material selection subsystem and a LIBS subsystem for partially sharing the same optical path;

[0060] The single-particle energetic material selection subsystem is used to select an imaging position for placing a single-particle energetic material, wherein the imaging position satisfies: the laser focusing position of the LIBS subsystem is at the same height as the position where the image is clearest in the single-particle energetic material selection subsystem, and the laser focusing spot of the LIBS subsystem at the imaging position is smaller than the area of ​​the single-particle energetic material;

[0061] The LIBS subsystem is used to emit laser light to excite a single particle of energetic material located at an imaging position;

[0062] The timing controller is used to control the triggering time of the LIBS subsystem and the shock wave image acquisition subsystem, so that the LIBS subsystem is triggered to emit laser light first, and the shock wave image acquisition subsystem acquires shock wave images of the single energetic particle after being excited at different time delays, and the triggering time of the shock wave image acquisition subsystem is later than the triggering time of the LIBS system, and the difference between the triggering times of the two is the delay, until the shock wave images of all the delay times of the different types of single energetic particles are acquired;

[0063] The optical processing subsystem is used to establish a linear prediction model of the shock wave characteristic velocity and detonation velocity of a single particle of energetic material according to different delayed shock wave images.

[0064] Specifically, Figure 1As shown, the single particle energetic material selection subsystem includes a first visible light source 8, a first dichroic mirror 4, a second dichroic mirror 5, a microscope objective lens 6 and a CMOS camera 9;

[0065] The first visible light source 8 is used to provide an illumination and observation light source for imaging the sample surface, wherein the illumination and observation light source is reflected by the first dichroic mirror 4, transmitted through the second dichroic mirror 5 and the microscope objective lens 6 to illuminate the sample surface placed on the sample stage 7, and the illumination and observation light source illuminates the sample surface to form a sample optical signal, which is sequentially transmitted through the microscope objective lens 6 and reflected by the second dichroic mirror 5 to enter the CMOS camera 9, and the CMOS camera 9 is used to convert the sample optical signal into a sample image.

[0066] Optionally, the first visible light source 8 is a white light LED, the first dichroic mirror 4 and the second dichroic mirror 5 transmit a wavelength of 1064 nm and reflect a wavelength band of 200-1000 nm, the microscope objective lens 6 has a magnification of 5 times and a numerical aperture of 0.14.

[0067] The LIBS subsystem is implemented based on LIBS technology, and uses a pulse laser 1 with a laser wavelength of 1064nm, a pulse width of 9ns, a single pulse laser energy of 10-120mJ@1064nm adjustable, a divergence angle of less than 0.5mrad, and a pulse repetition frequency of 1-10Hz adjustable as an excitation light source, provides injection energy, adjusts the emission energy of the pulse laser 1, and controls the laser energy at the focus of the focusing lens to 6mJ; specifically, the LIBS subsystem includes a pulse laser 1, a reflector 2, a concave lens 3-1, a plano-convex lens 3-2, a first dichroic mirror 4 for reflection, a second dichroic mirror 5, and a microscope objective 6;

[0068] The pulse laser 1 is used to provide a pulse laser light source, wherein the pulse laser light source is reflected by the reflector 2 in turn, and transmitted by the concave lens 3-1 and the plano-convex lens 3-2 to obtain a divergent pulse laser, wherein the reflector 2 is used to change the optical path direction of the 1064nm laser so that the laser is perpendicular to the horizontal plane and has a reflectivity greater than 99.5%. At the same time, the concave lens 3-1 and the plano-convex lens 3-2 are used in combination to change the divergence angle of the laser, expand the laser spot area to avoid damage to the subsequent optical lens group, and ultimately change the distance between the actual focus point of the laser and the microscope objective 6; the divergent pulse laser After being transmitted through the first dichroic mirror 4 and the second dichroic mirror 5, the divergent pulsed laser is finally focused by the microscope objective 6 and finally focused onto the single particle of energetic material on the sample stage 7. The excited single particle of energetic material generates high-temperature and high-pressure plasma and a rapid exothermic chemical reaction, and the surrounding air is violently compressed to generate an air shock wave. Among them, the first dichroic mirror 4 is used to change the light path direction of the first visible light source 8 so that it illuminates the sample surface and transmits the 1064nm laser. The second dichroic mirror 5 is used to change the light path direction of the sample optical signal so that it enters the CMOS camera 9 and transmits the 1064nm laser.

[0069] Among them, the distances between the concave lens 3-1 and the plano-convex lens 3-2 are different, and the divergence angles of the divergent pulse lasers obtained are different. With different divergence angles, the heights of the laser focusing positions obtained when the microscope objective 6 focuses the divergent pulse lasers are different. The smaller the distance, the larger the divergence angle, and the lower the height of the laser focusing position. Conversely, the larger the distance, the smaller the divergence angle, and the higher the height of the laser focusing position.

[0070] Optionally, the microscope objective lens 6 is a Mitutoyo model, with a magnification of 5 times and a numerical aperture of 0.14; the sample stage 7 can be adjusted in three-dimensional XYZ directions for placing samples. The CMOS camera 9 uses an area array CMOS photosensitive chip with an exposure time of 0.3-1000ms.

[0071] Based on this, the method for obtaining the imaging position is:

[0072] Change the distance between the sample stage 7 and the microscope objective 6 until the sample image in the CMOS camera 9 is clearest; adjust the distance between the concave lens 3-1 and the plano-convex lens 3-2 to change the height of the laser focusing position obtained when the microscope objective 6 focuses the divergent pulsed laser, until the laser focusing position is at the same height as the position where the sample image in the CMOS camera 9 is clearest, that is, the single-particle energetic material selection subsystem and the LIBS subsystem are focused on the same plane together, and the laser spot corresponding to the horizontal position of this plane is the smallest, so that only a single particle is excited.

[0073] After obtaining the imaging position, the imaging position can be marked. The marking method is:

[0074] A marker is placed on the sample stage, and the pulse laser 1 sends a pulse laser to generate an ablation pit on the marker, and the three-dimensional coordinates of the ablation pit are marked as the three-dimensional coordinates of the imaging position. In other words, before placing a single particle of energetic material, a laser pulse is emitted to find the ablation pit position in the field of view of the CMOS camera 9, and the ablation pit position is the laser focus. The sample stage 7 is moved to place a single particle of energetic material at the laser focus under the field of view of the CMOS camera 9, and then a laser pulse is emitted to achieve the excitation of the single particle of energetic material.

[0075] The shock wave image acquisition subsystem includes a second visible light source 10, a first convex lens 11, a slit 12, a second convex lens 13, a third convex lens 14, an aperture 15, a filter 16, a lens 17 and an enhanced sCMOS camera 18; at the same time, the single particle energetic material is located between the second convex lens 13 and the third convex lens 14, and the area where the plasma and shock wave generated after the single particle energetic material is excited is located is the disturbance area; wherein the second visible light source 10 uses a green LED light source as an imaging light source, the power is 20W, the size of the light emitting center is 5×5mm, and the luminous flux is 1800-2000lm , wavelength range is 520-525nm; the first convex lens 11 is a double-cemented achromatic lens, which focuses the light of the second visible light source 10; the second convex lens 13 is a double-cemented achromatic lens with a focal length of 150mm; the third convex lens 14 is a double-cemented achromatic lens with a focal length of 100mm; the filter 16 has a central wavelength of 520nm, a half-bandwidth of 10nm, and a peak transmittance of 85%; the lens 17 is the camera's own lens; the enhanced sCMOS camera 18 has a frame rate of 200MHz, a resolution of 2560×2160 pixels, a pixel size of 6.5μm, and a sensor size of 16.6×14.0mm;

[0076] The second visible light source 10 is used to provide a background light source for the plasma and shock wave disturbances generated after the single particle of energetic material is excited, wherein the background light source passes through the first convex lens 11, the slit 12, and the second convex lens 13 in sequence to form parallel light, and the parallel light passes through the disturbance area to form a shock light wave with uneven light intensity distribution, and the shock light wave passes through the third convex lens 14, the aperture 15, the filter 16, and the lens 17 in sequence to be incident on the enhanced sCMOS camera 18, forming a shock wave image in the enhanced sCMOS camera 18.

[0077] That is to say, the slit 13 forms an approximate point light source from the background light source emitted by the two focused visible light sources 10, and is placed at the front focal plane of the second convex lens 13. The emitted light beam passes through the second convex lens 13 and becomes parallel light. The parallel light passes through the microflow field area disturbed by the shock wave and converges through the third convex lens 14. An aperture 15 is placed at the focus of the third convex lens 14, and a filter 16 is placed thereafter to reduce the influence of strong light caused by the plasma's own radiation. The filter 16 has a central wavelength of 520 nm, a half bandwidth of 10 nm, and a peak transmittance of 85%. Finally, the shock wave image is presented in the enhanced sCMOS camera 18 through the lens 17.

[0078] It should be noted that the timing controller controls the triggering moment of the LIBS subsystem and the shock wave image acquisition subsystem, which actually controls the delay between the pulsed laser 1 and the enhanced sCMOS camera 18. The shock wave image acquisition subsystem captures shock wave images with different delays after laser emission. For each group of shock wave images of each sample, 15 delays are selected, namely 0.5μs, 1.0μs, 1.5μs, 2.0μs, 2.5μs, 3.0μs, 4.0μs, 5.0μs, 6.0μs, 7.0μs, 8.0μs, 9.0μs, 10.0μs, 15.0μs and 20.0μs.

[0079] It can be seen from this that Figure 1 The connection relationship of a laser-loaded single-particle energetic material detonation velocity rapid prediction system shown can be summarized as follows:

[0080] The reflecting mirror 2, the concave lens 3-1, the plano-convex lens 3-2, the first dichroic mirror 4, the second dichroic mirror 5, the microscope objective 6, and the sample stage 7 are arranged vertically in space from top to bottom in sequence. The mirror surfaces of the reflecting mirror 2, the first dichroic mirror 4, and the second dichroic mirror 5 are all placed at an angle of 45° to the horizontal plane. The planes of the concave lens 3-1, the plano-convex lens 3-2, the microscope objective 6, and the sample stage 7 are placed parallel to the horizontal plane. The planes of the first convex lens 11, the slit 12, the second convex lens 13, the third convex lens 14, the aperture 15, the filter 16, and the lens 17 are all placed perpendicular to the horizontal plane. The plane of the sample stage 7 is placed horizontally with the horizontal plane and is located at the microscope objective. The mirror 6 is at the best focal position where the imaging is clearest, and this position is also the laser focusing position. The gap of the slit 12 is located at the focus of the second convex lens 13, and the visible light passing through the second convex lens 13 forms parallel light. The aperture position of the aperture 15 is located at the focal position of the third convex lens 14, and the parallel light is focused after being converged by the third convex lens 14. The enhanced sCMOS camera 18 and its lens 17 are placed at a suitable position after the filter 16, and the suitable standard is that the image is clear and the size is suitable. The timing controller 19 connects the pulse laser 1 and the enhanced sCMOS camera 18 to control the delay between the two, and shoots the delayed shock wave image.

[0081] After the shock wave image is taken, the present invention extracts the shock wave front position information in the image, constructs a shock wave characteristic matrix, and thus establishes a linear prediction model of the shock wave characteristic velocity and detonation velocity of a single particle of energetic material; therefore, based on a laser-loaded single particle of energetic material detonation velocity rapid prediction system, the present invention provides a laser-loaded single particle of energetic material detonation velocity rapid prediction method, comprising the following steps:

[0082] S1: For each energetic material, two sets of shock wave images acquired at different delays after being excited are obtained, among which there are 15 different delays; for example, the triggering time of the shock wave image acquisition subsystem is 0.5μs, 1.0μs, 1.5μs, 2.0μs, 2.5μs, 3.0μs, 4.0μs, 5.0μs, 6.0μs, 7.0μs, 8.0μs, 9.0μs, 10.0μs, 15.0μs, 20.0μs after a single particle of energetic material is excited.

[0083] S2: For each energetic material, obtain the shock wave characteristic velocity vector of each group according to the two groups of shock wave images, wherein the method for obtaining the shock wave characteristic velocity vector of any group of shock wave images of each energetic material is specifically as follows:

[0084] S21: obtaining shock wave front position information in the shock wave images of the current group with different delays for each energetic material;

[0085] S22: Obtain the average value of the shock wave radius corresponding to each delay respectively, wherein the method for obtaining the average value of the shock wave radius of the nth delay is:

[0086] The major axis radius is obtained by performing an ellipse fitting on the front position information of the nth delayed shock wave Minor axis radius And the major axis radius Corresponding to the lateral propagation radius, the minor axis radius Corresponding to the longitudinal propagation radius, and the major axis radius With minor axis radius The average radius of the shock wave is recorded as

[0087] S23: Obtain the average propagation speed of the shock wave corresponding to each two delays, wherein the average propagation speed of the shock wave between the nth delay and the n+1th delay is The calculation method is:

[0088]

[0089] in, is the average radius of the n+1th delay, t n+1 is the n+1th delay, t nis the nth delay;

[0090] S24: Obtain the average transverse velocity of the shock wave and the average longitudinal propagation velocity of the shock wave corresponding to each two delays, wherein the average transverse velocity of the shock wave between the nth delay and the n+1th delay is and the average longitudinal velocity of the shock wave The calculation method is:

[0091]

[0092] in, is the major axis radius corresponding to the nth delay, is the minor axis radius corresponding to the nth delay;

[0093] S25: Obtain the shock wave propagation distance fitting curve corresponding to the current group of shock wave images through the Dewey model, and then derive the shock wave propagation distance fitting curve at 15 time delays to obtain the shock wave propagation fitting speed v at 15 time delays. n ;

[0094] In other words, the evolution of the shock wave front with time can be fitted by the Dewey model, and the fitting formula is:

[0095]

[0096] In the formula, a, b, c and d are fitting coefficients, R is the shock wave propagation distance, and t is the shock wave propagation time. The fitting velocity v of shock wave propagation at 15 different times is obtained by derivation of the fitting curve. n , select the shock wave radius at 1μs and divide it by 1μs to obtain the average shock wave propagation velocity v0 at 0.5μs.

[0097] S26: Combine the above shock wave velocity data in a specific order to construct a shock wave characteristic velocity vector I of the current group of shock wave images m as follows:

[0098]

[0099] Wherein, v0 is the average propagation velocity of the shock wave with a delay of 0.5 μs, which is obtained by dividing the radius of the shock wave with a delay of 1 μs by 1 μs; m = 1, 2;

[0100] S3: Construct the shock wave characteristic velocity matrix q of the current energetic material by using the shock wave characteristic velocity vectors corresponding to the two different delays:

[0101]

[0102] S4: The shock wave characteristic velocity vectors I1 and I2 corresponding to each energetic material are averaged to obtain the final shock wave characteristic velocity matrix Q for each energetic material. k , k is the label of each energetic material, and the shock wave characteristic velocity matrix of all energetic materials is Q:

[0103]

[0104] S5: The shock wave characteristic velocity matrix Q is fitted by an intelligent algorithm based on partial least squares regression to obtain a linear prediction model of the shock wave characteristic velocity and detonation velocity of a single particle of energetic material, thereby realizing the prediction of the macroscopic detonation velocity of a single particle of energetic material based on laser loading induced shock waves.

[0105] Furthermore, the method for obtaining the shock wave front of any shock wave image is as follows:

[0106] Calculate the gradient value matrix of the shock wave image along the horizontal positive direction, horizontal negative direction, vertical negative direction, and vertical positive direction to obtain a more obvious gradient map of the shock wave front in the four directions;

[0107] The gradient images in each direction are smoothed and filtered respectively, and then based on the Laida criterion, the gradient intensity threshold is used to directly remove the significant noise points in the gradient images after smoothing filtering whose gradient intensity fluctuation is greater than a set multiple, such as m times the standard deviation, to obtain the smoothed gradient images in each direction; wherein the value of m is selected according to the actual image situation;

[0108] The smooth gradient images in each direction are processed by opening and closing operations respectively, wherein the opening operation is used to eliminate the secondary noise points whose connectivity does not meet the set requirements, and the closing operation is used to eliminate the pulse noise points inside the shock wave. Then, the smooth gradients processed by the opening and closing operations are subjected to denoising by the median filter to obtain the primary denoising images in each direction after the noise points are removed;

[0109] The first denoised image corresponding to the positive and negative gradient images in the horizontal direction and the first denoised image corresponding to the positive and negative gradient images in the vertical direction are spliced ​​respectively to obtain a spliced ​​gradient image, wherein the splitting line of the horizontal splicing is determined by the estimated value of the laser incident line position, and the splitting line of the vertical splicing is determined by the estimated value of the height position of the sample cover glass surface;

[0110] Calculate the gradient value matrix of the first splicing gradient image along the horizontal positive direction, horizontal negative direction, vertical negative direction, and vertical positive direction to obtain the secondary gradient images in four directions; the secondary gradient calculation is to find the edge line of the optimized first splicing gradient image;

[0111] The secondary gradient images in four directions are spliced ​​to obtain a secondary spliced ​​gradient image;

[0112] The secondary splicing gradient image is subjected to secondary denoising by using a random sampling consensus algorithm, and the secondary gradient image after secondary denoising is used as the final shock wave front. Specifically, the method of performing secondary denoising by the random sampling consensus algorithm (RANSAC) is as follows:

[0113] Randomly select three points of the quadratic gradient result image for circle fitting to obtain the coordinates of the center and radius of the circle. Calculate the distance from the remaining points to the center and compare it with the fitting radius. Record the number of points less than 2σ. Repeat the above steps k times (k is the number of non-zero pixels in the quadratic gradient result image). Select the coordinates of the center and radius of the circle with the largest number of points as the parameters of the fitting circle. Calculate the distance from the remaining points to the center of the final fitting circle and compare it with the radius of the final fitting circle. Remove the points greater than 3σ as noise points. The quadratic gradient image after secondary denoising is the final shock wave front.

[0114] Furthermore, the method for using a laser-loaded single-particle energetic material detonation velocity rapid prediction system provided by the present invention is summarized as follows:

[0115] Turn on the second visible light source 10 and the enhanced sCMOS camera 18, and adjust the second visible light source 10, lens group 11, 13, 14, 16, 17, slit 12, and aperture 15 in the shock wave image acquisition system to be coaxial until the shock wave image can be clearly captured.

[0116] The optical lens group 2-5 of the single-particle energetic material selection system and LIBS and the central optical axes of the microscope objective lens 6 are adjusted to coincide with each other, and the first visible light source 8 and the CMOS camera 9 are turned on.

[0117] The LIBS system is adjusted and the distance between the microscope objective 6 and the sample stage 7 is adjusted until the image in the CMOS camera 9 is the clearest.

[0118] The distance between the concave lens 3-1 and the plano-convex lens 3-2 is adjusted to change the laser spot size and the divergence angle until the laser is focused on the surface of the sample stage 7 when the image of the CMOS camera 9 is clearest.

[0119] Before placing the sample, a laser pulse is emitted to leave an ablation pit. The position of the ablation pit is the laser focusing position. The sample is placed, and the horizontal position of the sample stage 7 is moved. At the same time, the real-time image in the CMOS camera 9 is observed until a particle of the energetic material is located at the laser focusing position.

[0120] After the position of the sample stage 7 is fixed, a laser pulse is emitted, and the single particle of energetic material located at the laser focus is excited to generate plasma while compressing the surrounding gas environment to generate a shock wave. When the uniform parallel light passing through the area between the second convex lens 13 and the third convex lens 14 passes through the shock wave disturbance area with uneven density distribution, the density at the front of the shock wave is relatively high, so the parallel light will be deflected downward relative to the horizontal direction after passing through the shock wave disturbance area, and the brightness and darkness will reverse the change of the derivative of the refractive index along the spatial distance in the shock wave disturbance space, and finally the light intensity distribution reaching the image-intensified sCMOS camera 18 is uneven, forming a shock wave image.

[0121] The timing controller 19 controls the enhanced sCMOS camera 18 to capture shock wave images at different delay times after the pulse laser 1 emits the pulse laser. For each sample, shock wave images are captured at 15 delay times, namely, 0.5μs, 1.0μs, 1.5μs, 2.0μs, 2.5μs, 3.0μs, 4.0μs, 5.0μs, 6.0μs, 7.0μs, 8.0μs, 9.0μs, 10.0μs, 15.0μs, and 20.0μs.

[0122] After a series of shock wave images with different time delays are taken, the shock wave front position information of each image is extracted: in the shock wave image, there will be a dark area behind the shock wave front and a bright area in front of it, with peaks and troughs appearing successively in intensity, and the shock wave front is the point where the grayscale value changes fastest between the peaks and troughs, that is, the point where the gradient maximum value is located. The shock wave front identification is to extract the point with the maximum grayscale gradient, and the shock wave image is processed by gradient calculation, denoising, splicing, secondary gradient calculation, and secondary denoising. The secondary gradient image after secondary denoising is the final shock wave front.

[0123] The shock wave characteristic velocity matrix Q is calculated.

[0124] Through an intelligent algorithm based on partial least squares regression, a linear model for predicting the macroscopic detonation velocity of the shock wave characteristic velocity I3 of particle-scale energetic materials is established, ultimately achieving safe, rapid, and ultra-small-amount prediction of the detonation velocity of energetic materials at the particle-scale level.

[0125] In summary, the present invention provides a method and system for rapidly predicting the detonation velocity of a single-particle energetic material loaded by laser, using pulsed laser to load a single-particle energetic material to generate a shock wave, using an enhanced sCMOS camera to collect a shock wave image, calculating the characteristic velocity of the shock wave through the shock wave position information in the shock wave image, and establishing a linear relationship model between the characteristic velocity of the shock wave and the known macroscopic detonation velocity through partial least squares regression, thereby realizing rapid prediction of the detonation velocity of the energetic material. The present invention consumes very little sample, eliminates the interaction between particles, has high safety, can realize that only one single-particle energetic material is excited each time the laser pulse is used, and only energetic materials of the particle level are required to complete the test, which is of great significance for improving the safety of energetic material testing and for performing performance tests on energetic materials of ultra-small amounts or even several single-particle levels.

[0126] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may certainly make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A laser-loaded single-particle energetic material detonation velocity rapid prediction system, characterized in that: It includes a timing controller, a shock wave image acquisition subsystem, an optical processing subsystem, and a single-particle energetic material selection subsystem and a LIBS subsystem for some common optical paths; The single-particle energetic material selection subsystem is used to select an imaging position for placing a single-particle energetic material, wherein the imaging position satisfies: the laser focusing position of the LIBS subsystem is at the same height as the position where the image is clearest in the single-particle energetic material selection subsystem, and the laser focusing spot of the LIBS subsystem at the imaging position is smaller than the area of ​​the single-particle energetic material; The LIBS subsystem is used to emit laser light to excite a single particle of energetic material located at an imaging position; The timing controller is used to control the triggering time of the LIBS subsystem and the shock wave image acquisition subsystem, so that the LIBS subsystem is triggered to emit laser light first, and the shock wave image acquisition subsystem acquires shock wave images of the single energetic particle after being excited at different time delays, and the triggering time of the shock wave image acquisition subsystem is later than the triggering time of the LIBS system, and the difference between the triggering times of the two is the delay, until the shock wave images of all the delay times of the different types of single energetic particles are acquired; The optical processing subsystem is used to establish a linear prediction model of the shock wave characteristic velocity and detonation velocity of a single particle of energetic material according to different delayed shock wave images.

2. A laser-loaded single-particle energetic material detonation velocity rapid prediction system as claimed in claim 1, characterized in that: The single-particle energetic material selection subsystem comprises a first visible light source (8), a first dichroic mirror (4), a second dichroic mirror (5), a microscope objective lens (6) and a CMOS camera (9); The first visible light source (8) is used to provide an illumination observation light source for imaging the sample surface, wherein the illumination observation light source is reflected by the first dichroic mirror (4), transmitted through the second dichroic mirror (5) and the microscope objective lens (6) to illuminate the sample surface placed on the sample stage (7), the illumination observation light source illuminates the sample surface to form a sample optical signal, the sample optical signal is sequentially transmitted through the microscope objective lens (6), reflected by the second dichroic mirror (5) and enters the CMOS camera (9), and the CMOS camera (9) is used to convert the sample optical signal into a sample image.

3. A laser-loaded single-particle energetic material detonation velocity rapid prediction system as claimed in claim 2, characterized in that: The LIBS subsystem comprises a pulse laser (1), a reflector (2), a concave lens (3-1), a plano-convex lens (3-2), a first dichroic mirror (4) for reflection, a second dichroic mirror (5) and a microscope objective lens (6); The pulse laser (1) is used to provide a pulse laser light source, wherein the pulse laser light source is reflected by a reflector (2), transmitted by a concave lens (3-1) and a plano-convex lens (3-2) in sequence, and a divergent pulse laser is obtained; the divergent pulse laser is transmitted by a first dichroic mirror (4), a second dichroic mirror (5), and finally the divergent pulse laser is focused by a microscope objective lens (6), and finally focused onto a single particle of energetic material on a sample stage (7); The distances between the concave lens (3-1) and the plano-convex lens (3-2) are different, and the divergence angles of the divergent pulse lasers obtained are different. When the divergence angles are different, the heights of the laser focus positions obtained when the microscope objective lens (6) focuses the divergent pulse lasers are different. The smaller the distance, the larger the divergence angle and the lower the height of the laser focus position. Conversely, the larger the distance, the smaller the divergence angle and the higher the height of the laser focus position.

4. A laser-loaded single-particle energetic material detonation velocity rapid prediction system as claimed in claim 3, characterized in that: The method for obtaining the imaging position is: Changing the distance between the sample stage (7) and the microscope objective lens (6) until the sample image in the CMOS camera (9) is clearest; The distance between the concave lens (3-1) and the plano-convex lens (3-2) is adjusted to change the height of the laser focus position obtained when the microscope objective lens (6) focuses the divergent pulse laser, until the laser focus position is at the same height as the position where the sample image in the CMOS camera (9) is clearest.

5. A laser-loaded single-particle energetic material detonation velocity rapid prediction system as claimed in claim 4, characterized in that: After obtaining the imaging position, mark the imaging position. The marking method is: A marker is placed on the sample stage, and a pulse laser (1) emits a pulse laser to generate an ablation pit on the marker, and the three-dimensional coordinates of the ablation pit are marked as the three-dimensional coordinates of the imaging position.

6. A laser-loaded single-particle energetic material detonation velocity rapid prediction system as claimed in claim 1, characterized in that: The shock wave image acquisition subsystem comprises a second visible light source (10), a first convex lens (11), a slit (12), a second convex lens (13), a third convex lens (14), an aperture (15), a filter (16), a lens (17) and an enhanced sCMOS camera (18); meanwhile, the single particle of energetic material is located between the second convex lens (13) and the third convex lens (14), and the area where the plasma and shock wave generated after the single particle of energetic material is excited is located is the disturbance area; The second visible light source (10) is used to provide a background light source for shock wave disturbance generated after a single particle of energetic material is excited, wherein the background light source passes through a first convex lens (11), a slit (12), and a second convex lens (13) in sequence to form parallel light, and the parallel light is deflected after passing through a disturbance area, and the deflected light passes through a third convex lens (14), an aperture (15), a filter (16), and a lens (17) in sequence to be incident on an enhanced sCMOS camera (18), thereby forming a shock wave image in the enhanced sCMOS camera (18).

7. A laser-loaded single-particle energetic material detonation velocity rapid prediction system as claimed in claim 1, characterized in that: The time delay of the shock wave image acquisition subsystem is 0.5μs, 1.0μs, 1.5μs, 2.0μs, 2.5μs, 3.0μs, 4.0μs, 5.0μs, 6.0μs, 7.0μs, 8.0μs, 9.0μs, 10.0μs, 15.0μs, and 20.0μs after a single particle of energetic material is excited.

8. A method for rapidly predicting the detonation velocity of a single particle of energetic material loaded by laser based on the system for rapidly predicting the detonation velocity of a single particle of energetic material loaded by laser according to claim 1, characterized in that: The following steps are involved: S1: For each energetic material, two sets of shock wave images collected at different time delays after being excited are obtained, among which there are 15 different time delays; S2: For each energetic material, obtain the shock wave characteristic velocity vector of each group according to the two groups of shock wave images, wherein the method for obtaining the shock wave characteristic velocity vector of any group of shock wave images of each energetic material is specifically as follows: S21: obtaining shock wave front position information in the shock wave images of the current group with different delays for each energetic material; S22: Obtain the average value of the shock wave radius corresponding to each delay respectively, wherein the method for obtaining the average value of the shock wave radius of the nth delay is: The major axis radius is obtained by performing an ellipse fitting on the front position information of the nth delayed shock wave Minor axis radius And the major axis radius Corresponding to the lateral propagation radius, the minor axis radius Corresponding to the longitudinal propagation radius, and the major axis radius With minor axis radius The average radius is recorded as the shock wave radius n=1,2,…,15; S23: Obtain the average propagation speed of the shock wave corresponding to each two delays, wherein the average propagation speed of the shock wave between the nth delay and the n+1th delay is The calculation method is: in, is the average radius of the n+1th delay, t n+1 is the n+1th delay, t n is the nth delay; S24: Obtain the average transverse velocity of the shock wave and the average longitudinal propagation velocity of the shock wave corresponding to each two delays, wherein the average transverse velocity of the shock wave between the nth delay and the n+1th delay is and the average longitudinal velocity of the shock wave The calculation method is: in, is the major axis radius corresponding to the nth delay, is the minor axis radius corresponding to the nth delay; S25: Obtain the shock wave propagation distance fitting curve corresponding to the current group of shock wave images through the Dewey model, and then derive the shock wave propagation distance fitting curve at 15 delays to obtain the shock wave propagation fitting speed v of 15 delays n ; S26: Constructing the shock wave characteristic velocity vector I of the current group of shock wave images m as follows: Where v0 is the average propagation velocity of the shock wave with a delay of 0.5 μs, which is obtained by dividing the radius of the shock wave with a delay of 1 μs by 1 μs; m = 1, 2; S3: Construct the shock wave characteristic velocity matrix q of the current energetic material by using the shock wave characteristic velocity vectors corresponding to the two different delays: S4: The shock wave characteristic velocity vectors I1 and I2 corresponding to each energetic material are averaged to obtain the final shock wave characteristic velocity matrix Q for each energetic material. k , k is the label of each energetic material, and the shock wave characteristic velocity matrix of all energetic materials is Q: S5: The shock wave characteristic velocity matrix Q is fitted by an intelligent algorithm based on partial least squares regression to obtain a linear prediction model for the shock wave characteristic velocity and detonation velocity of a single particle of energetic material.

9. A method for rapid prediction of detonation velocity of a laser-loaded single-particle energetic material according to claim 7, characterized in that: The method for obtaining the shock wave front of any shock wave image is: Calculate the gradient value matrix of the shock wave image along the horizontal positive direction, the horizontal negative direction, the vertical negative direction, and the vertical positive direction to obtain the gradient maps in four directions; The gradient images in each direction are smoothed and filtered respectively, and then based on the Laida criterion, the gradient intensity threshold is used to directly remove the significant noise points in the gradient images after smoothing filtering whose gradient intensity fluctuation is greater than the set multiple standard deviation, and the smoothed gradient images in each direction are obtained; The smooth gradient images in each direction are processed by opening and closing operations respectively, wherein the opening operation is used to eliminate the secondary noise points whose connectivity does not meet the set requirements, and the closing operation is used to eliminate the pulse noise points inside the shock wave. Then, the smooth gradients processed by the opening and closing operations are subjected to denoising by the median filter to obtain the primary denoising images in each direction after the noise points are removed; The first denoised image corresponding to the positive and negative gradient images in the horizontal direction and the first denoised image corresponding to the positive and negative gradient images in the vertical direction are spliced ​​respectively to obtain a spliced ​​gradient image, wherein the splitting line of the horizontal splicing is determined by the estimated value of the laser incident line position, and the splitting line of the vertical splicing is determined by the estimated value of the height position of the sample cover glass surface; Calculate the gradient value matrix of the spliced ​​gradient image along the horizontal positive direction, horizontal negative direction, vertical negative direction, and vertical positive direction to obtain the secondary gradient image in four directions; The secondary gradient images in four directions are spliced ​​to obtain a secondary spliced ​​gradient image; The secondary splicing gradient image is subjected to secondary denoising by means of a random sampling consistency algorithm, and the secondary gradient image after secondary denoising is used as the final shock wave front.

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