Smoke scattering infrared laser simulation system and method based on diffusion model

Abstract

The present invention discloses a system and method for simulating and emulating infrared lasers of smoke scattering based on a diffusion model. The system includes a smoke diffusion process simulation subsystem and a smoke scattering process simulation subsystem. The method is as follows: first, the smoke diffusion process simulation subsystem generates smoke particles, performs statistics on smoke particle state information, analyzes smoke particle interactions, and performs smoke particle state transfer and state updates. Then, the smoke scattering process simulation subsystem uses a laser to emit photons, calculates the photons scattered by smoke particles, and finally uses a detector to receive photons to obtain the ratio of the received photon count to the number of emitted photons, which is the transmittance of the corresponding smoke. The present invention can fully simulate the effects of collisions, agglomeration, and external forces between smoke particles in actual environments, thereby improving the accuracy of the simulation method. It can also simulate the dynamic changes in the various state attributes of the smoke during its formation, and can evaluate the interference effect of the smoke on the infrared laser fuse.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic countermeasures, in particular to a smoke screen scattering infrared laser simulation system and method based on a diffusion model. Background Art

[0002] In modern warfare, passive jamming methods such as smoke screens are often used to prevent infrared-guided warheads from tracking critical targets or to prevent infrared imaging equipment from conducting reconnaissance and surveillance of sensitive areas. For warheads equipped with infrared laser fuzes, their ability to resist smoke jamming significantly impacts attack accuracy and, in turn, their lethality. Therefore, evaluating the laser fuze's smoke jamming resistance is a crucial component of laser-guided warhead effectiveness assessment. Using computer simulation to evaluate the effect of smoke screens on infrared laser scattering offers advantages such as high repeatability and low cost. This simulation method can be applied to performance simulation testing during the development of new infrared laser fuzes and smoke agents.

[0003] Currently, there are two main approaches to numerically calculate or simulate the effect of smoke screens on infrared laser scattering. One approach uses the van de Hulst approximation, utilizing parameters such as the laser wavelength, smoke particle radius, and the complex refractive index of smoke particles to calculate the absorption, scattering, and attenuation factors of smoke particles. This leads to the mass extinction coefficient of the smoke, which is then combined with the smoke particle concentration and the laser's penetration distance in the smoke to determine the smoke's transmittance to the laser. For example, the paper "Numerical Simulation Analysis of Laser Transmission Characteristics in Smoke" by Li Xiaofeng et al. from the School of Electronic Information at Sichuan University. The other approach uses a Monte Carlo calculation model, treating the laser as a beam composed of multiple photons. The interaction between photons and particles in a randomly distributed medium is elastic scattering, transforming the laser transmission problem into a photon transmission problem. Since the distribution of particles in a smoke screen is completely random, the photons' scattering changes their direction of motion. This new direction of motion is related to the scattering phase function and the random numbers generated by the computer. When photons undergo multiple scattering, each scattering is only related to the previous scattering, and this process is repeated until the photon weight is less than the threshold, or the photon leaves the smoke screen, or reaches the receiving interface. After tracking the behavior of a large number of photons, the number of photons that finally reach the receiving interface, as well as parameters such as their position and total distance traveled, are counted to obtain information such as the smoke screen transmittance, as shown in the document "Monte Carlo Simulation of Laser Transmission in Smoke Screens" by Wang Hongxia et al. from the Second Artillery Engineering University.

[0004] Existing numerical calculation or simulation methods for the effect of smoke scattering infrared lasers have the following problems:

[0005] (1) Existing methods all assume that smoke particles are uniformly and stably distributed in space. However, in actual smoke interference, the diffusion process of smoke particles is affected by collisions, agglomeration, and external forces, resulting in smoke particles not being uniformly and stably distributed in space. Therefore, existing methods cannot simulate the smoke state precisely and accurately.

[0006] (2) The existing methods can only approximately simulate the scattering and transmission effects of smoke on infrared lasers when the smoke screen is uniformly and stably distributed in space. They cannot simulate the dynamic changes in the scattering and transmission effects of smoke on infrared lasers during the formation of the smoke screen. Therefore, the existing methods do not have the ability to evaluate the full process of smoke screen interference with infrared laser fuses. Summary of the Invention

[0007] The purpose of the present invention is to provide a smoke scattering infrared laser simulation system and method that can simulate the smoke state precisely and accurately and simulate the dynamic changes of the scattering and transmission effects of the smoke on the infrared laser during the smoke formation process.

[0008] The technical solution to achieve the purpose of the present invention is: a smoke scattering infrared laser simulation system based on a diffusion model, including a smoke diffusion process simulation subsystem and a smoke scattering process simulation subsystem;

[0009] The smoke diffusion process simulation subsystem includes four modules: smoke particle generation, smoke particle state information statistics, smoke particle interaction analysis, and smoke particle state transfer and state update.

[0010] The smoke particle generation module sends the smoke particles into the simulation system by spraying them through the smoke generating device;

[0011] The smoke particle state information statistics module measures and counts the state attributes of the smoke particles during their generation process;

[0012] The smoke particle interaction analysis module analyzes and calculates the collision, coagulation and external force between smoke particles during the diffusion process;

[0013] The smoke particle state transfer and state update module updates the state information of the smoke particles;

[0014] The smoke scattering process simulation subsystem includes three modules: laser emitting photons, smoke particle scattering photons, and detector receiving photons:

[0015] The laser emits a photon module. The laser emits laser light, which is considered to emit a large number of photons. The frequency and movement direction of the photons are related to the characteristics of the laser itself.

[0016] The smoke particle scattering photon module determines the scattering direction of photons scattered by collision with smoke particles during their travel, based on the current state of the smoke particles, by calculating the intensity distribution of Mie scattering and combining it with the generated random number;

[0017] The detector receives the photon module, which receives photons that meet the constraints of the detector's own characteristics according to the detector's own characteristics.

[0018] A method for simulating infrared laser scattering by smoke based on a diffusion model includes the following steps:

[0019] Step 1: Start the simulation, simulate the smoke diffusion process, and input physical constants and external environment parameters;

[0020] Step 2: Input the spatial location information of the smoke generating device and smoke-related parameters;

[0021] Step 3, input relevant parameters of the smoke agent;

[0022] Step 4: Set the time granularity of the diffusion process simulation, that is, the time step corresponding to one cycle execution and the total time length of the diffusion process simulation;

[0023] Step 5: The smoke generating device generates smoke particles and adds the status information of the smoke particles to the smoke particle status information table;

[0024] Step 6: Calculate the external forces acting on the smoke particles, then calculate the random motions caused by the interaction between the smoke particles and the air particles, and update the position and velocity information of the smoke particles under these forces into the existing particle state information table;

[0025] Step 7: Count the collision information between smoke particles and determine whether the condensation condition is met. If the condensation condition is met, calculate the state information of the new particle and update it to the state information table, and delete the state information of the corresponding particle before the collision. If the condensation condition is not met, calculate the speed of each particle after the collision and update the new speed information to the state information table. Finally, increase the diffusion process simulation time by one diffusion process time step.

[0026] Step 8: Check whether the current simulation time reaches the total time length. If it reaches the total time length, go to step 9 to simulate the smoke scattering process; if it does not reach the total time length, return to step 5 and perform the simulation process of the next time step;

[0027] Step 9: Input the spatial position information of the laser and the laser related parameters;

[0028] Step 10: Input the spatial location information of the detector and related parameters of the detector;

[0029] Step 11: setting the number of emitted photons, the time granularity of the scattering process simulation, and the time length of the scattering process simulation, and setting the counts of emitted photons and received photons to zero respectively;

[0030] Step 12: The laser emits a photon, records the position and direction of the photon, adds 1 to the emitted photon count, and determines whether the emitted photon count is greater than the set number of emitted photons. If so, proceed to step 16; if not, proceed to step 13.

[0031] Step 13: Calculate the new position of the photon after one time step, update the position information of the photon, and determine whether the photon has reached the detector. If the photon has reached the detector, proceed to step 15; if the photon has not reached the detector, proceed to step 14;

[0032] Step 14: Look up the smoke particle state information table to determine whether the photon collides with the smoke particle. If a collision occurs, calculate the spatial distribution of the Mie scattering intensity and determine the scattering direction of the photon based on the generated random number, and update the photon's motion direction information. If no collision occurs, do nothing. Finally, increase the scattering process simulation time by one scattering process time step, and return to step 13.

[0033] Step 15: Determine whether the photon meets the constraints of the detector reception. If the constraints are met, the received photon count is increased by 1, and the process returns to step 12; if the constraints are not met, the received photon count remains unchanged, and the process returns to step 12;

[0034] Step 16: The simulation ends, and the ratio of the received photon count to the emitted photon count corresponds to the transmittance of the smoke screen.

[0035] Compared with the prior art, the present invention has the following significant advantages: (1) It introduces the simulation of the smoke diffusion process, so that the collision, agglomeration and influence of external forces between smoke particles in the actual environment can be completely and accurately simulated, thereby improving the accuracy of the simulation method; (2) Including the smoke diffusion process can effectively simulate the dynamic change process of various state attributes of the smoke during the smoke formation process, thereby having the ability to evaluate the effectiveness of the smoke interference on the infrared laser fuse throughout the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The diagram is a structural diagram of a smoke scattering infrared laser simulation system based on a diffusion model of the present invention.

[0037] Figure 2 The figure is a flow chart of a method for simulating infrared laser scattering by smoke based on a diffusion model of the present invention. DETAILED DESCRIPTION

[0038] The present invention provides a smoke scattering infrared laser simulation system based on a diffusion model, comprising a smoke diffusion process simulation subsystem and a smoke scattering process simulation subsystem;

[0039] The smoke diffusion process simulation subsystem includes four modules: smoke particle generation, smoke particle state information statistics, smoke particle interaction analysis, and smoke particle state transfer and state update.

[0040] The smoke particle generation module sends the smoke particles into the simulation system by spraying them through the smoke generating device;

[0041] The smoke particle state information statistics module measures and counts the state attributes of the smoke particles during their generation process;

[0042] The smoke particle interaction analysis module analyzes and calculates the collision, coagulation and external force between smoke particles during the diffusion process;

[0043] The smoke particle state transfer and state update module updates the state information of the smoke particles;

[0044] The smoke scattering process simulation subsystem includes three modules: laser emitting photons, smoke particle scattering photons, and detector receiving photons:

[0045] The laser emits a photon module. The laser emits laser light, which is considered to emit a large number of photons. The frequency and movement direction of the photons are related to the characteristics of the laser itself.

[0046] The smoke particle scattering photon module determines the scattering direction of photons scattered by collision with smoke particles during their travel, based on the current state of the smoke particles, by calculating the intensity distribution of Mie scattering and combining it with the generated random number;

[0047] The detector receives the photon module, which receives photons that meet the constraints of the detector's own characteristics according to the detector's own characteristics.

[0048] As a specific example, the smoke diffusion process simulation subsystem simulates the collision, coagulation and influence of external forces between smoke particles in a real environment.

[0049] As a specific example, the state attributes of smoke particles during the generation process include smoke particle velocity, particle size, density, and refractive index.

[0050] As a specific example, the state properties of smoke particles during the generation process are determined by the properties of the smoke agent itself, the characteristics of the smoke generating device, and environmental parameters.

[0051] As a specific example, the external forces acting on smoke particles during the diffusion process include gravity, buoyancy, and air resistance.

[0052] As a specific example, the smoke particle state transfer and state update module updates the state information of the smoke particles, including the position, velocity and particle size information of the smoke particles after the interaction occurs.

[0053] The present invention provides a method for simulating infrared laser scattering by smoke based on a diffusion model, comprising the following steps:

[0054] Step 1: Start the simulation, simulate the smoke diffusion process, and input physical constants and external environment parameters;

[0055] Step 2: Input the spatial location information of the smoke generating device and smoke-related parameters;

[0056] Step 3, input relevant parameters of the smoke agent;

[0057] Step 4: Set the time granularity of the diffusion process simulation, that is, the time step corresponding to one cycle execution and the total time length of the diffusion process simulation;

[0058] Step 5: The smoke generating device generates smoke particles and adds the status information of the smoke particles to the smoke particle status information table;

[0059] Step 6: Calculate the external forces acting on the smoke particles, then calculate the random motions caused by the interaction between the smoke particles and the air particles, and update the position and velocity information of the smoke particles under these forces into the existing particle state information table;

[0060] Step 7: Count the collision information between smoke particles and determine whether the condensation condition is met. If the condensation condition is met, calculate the state information of the new particle and update it to the state information table, and delete the state information of the corresponding particle before the collision. If the condensation condition is not met, calculate the speed of each particle after the collision and update the new speed information to the state information table. Finally, increase the diffusion process simulation time by one diffusion process time step.

[0061] Step 8: Check whether the current simulation time reaches the total time length. If it reaches the total time length, go to step 9 to simulate the smoke scattering process; if it does not reach the total time length, return to step 5 and perform the simulation process of the next time step;

[0062] Step 9: Input the spatial position information of the laser and the laser related parameters;

[0063] Step 10: Input the spatial location information of the detector and related parameters of the detector;

[0064] Step 11: setting the number of emitted photons, the time granularity of the scattering process simulation, and the time length of the scattering process simulation, and setting the counts of emitted photons and received photons to zero respectively;

[0065] Step 12: The laser emits a photon, records the position and direction of the photon, adds 1 to the emitted photon count, and determines whether the emitted photon count is greater than the set number of emitted photons. If so, proceed to step 16; if not, proceed to step 13.

[0066] Step 13: Calculate the new position of the photon after one time step, update the position information of the photon, and determine whether the photon has reached the detector. If the photon has reached the detector, proceed to step 15; if the photon has not reached the detector, proceed to step 14;

[0067] Step 14: Look up the smoke particle state information table to determine whether the photon collides with the smoke particle. If a collision occurs, calculate the spatial distribution of the Mie scattering intensity and determine the scattering direction of the photon based on the generated random number, and update the photon's motion direction information. If no collision occurs, do nothing. Finally, increase the scattering process simulation time by one scattering process time step, and return to step 13.

[0068] Step 15: Determine whether the photon meets the constraints of the detector reception. If the constraints are met, the received photon count is increased by 1, and the process returns to step 12; if the constraints are not met, the received photon count remains unchanged, and the process returns to step 12;

[0069] Step 16: The simulation ends, and the ratio of the received photon count to the emitted photon count corresponds to the transmittance of the smoke screen.

[0070] As a specific example, the relevant parameters of the smoke agent in step 3 include particle size distribution, refractive index and density;

[0071] The particle size distribution of the smoke agent satisfies the Rosin-Rammler cumulative distribution function F d :

[0072]

[0073] Where d is the particle size, is the average particle size, and n is the particle size distribution index.

[0074] As a specific example, the state information of the smoke particles in step 5 includes external force, Brownian motion, collision and coagulation. The interaction process is added according to the actual situation, and the update method of the smoke particle state information table is adjusted.

[0075] As a specific example, in step 14, the spatial distribution of the Mie scattering intensity is calculated and the scattering direction of the photon is determined in combination with the generated random number, as follows:

[0076] When the incident light is unpolarized natural light, the Mie scattered light intensity has the following spatial distribution:

[0077]

[0078] Where, I λ is the scattered light intensity, that is, the energy per unit area per unit time; I 0λ is the incident light intensity, that is, the energy per unit area per unit time; i1 is the intensity function of the horizontal polarization component of the scattered light, i2 is the intensity function of the vertical polarization component of the scattered light, λ is the wavelength of the incident light, χ = 2πr / λ is the particle size parameter, R is the distance between the observation point and the center of the particle, m is the refractive index of the particle relative to the surrounding medium, and θ is the angle between the scattered light and the incident light, that is, the scattering angle;

[0079] The mathematical expressions of i1 and i2 are written as infinite series:

[0080]

[0081]

[0082] Where a n and b n is the amplitude function, all of which are complex numbers and are related to χ and m, but θ is independent of π; n and τ n is a function that is only related to the scattering angle θ; a n 、b n , π n and τ n The expressions are:

[0083]

[0084]

[0085]

[0086]

[0087] Where, ψ n and ζ n is a half-integer order Bessel function and a second-kind Hankel function, expressed as:

[0088]

[0089]

[0090] P n (cosθ) and are the Legendre functions and first-order associated Legendre functions with respect to cosθ.

[0091] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0092] Example

[0093] Combine Figure 1 The present invention provides a smoke scattering infrared laser simulation system based on a diffusion model, including a smoke diffusion process simulation subsystem and a smoke scattering process simulation subsystem;

[0094] The smoke diffusion process simulation subsystem includes four modules: smoke particle generation, smoke particle state information statistics, smoke particle interaction analysis, and smoke particle state transfer and state update.

[0095] The smoke particle generation module sends the smoke particles into the simulation system by spraying them through the smoke generating device;

[0096] The smoke particle state information statistics module measures and compiles statistics on the state attributes of smoke particles during their generation process. The smoke particle generation process imparts various state attributes to smoke particles, such as velocity, particle size, density, and refractive index. These state attributes are determined by the properties of the smoke agent itself, the characteristics of the smoke generating device, and environmental parameters such as temperature, humidity, and air pressure. The smoke particle state information statistics module is used to measure and compile statistics on these states.

[0097] The smoke particle interaction analysis module analyzes and calculates the collisions, coalescence, and external forces between smoke particles during the diffusion process. In the system, smoke particles are affected by external forces such as gravity, buoyancy, and air resistance. Smoke particles interact with air particles to produce random motions such as Brownian motion. Smoke particles collide with each other and coalesce under certain conditions. The smoke particle interaction analysis module is used to analyze and calculate these processes.

[0098] The smoke particle state transfer and state update module updates the state information of the smoke particles; after the interaction occurs, the state information of the smoke particles, such as the position, speed, and particle size, changes, i.e., a state transfer occurs, and the smoke particle state transfer and state update module updates the state information of the smoke particles;

[0099] The smoke scattering process simulation subsystem includes three modules: laser emitting photons, smoke particle scattering photons, and detector receiving photons:

[0100] The laser emits a photon module. The laser emits laser light, which can be regarded as emitting a large number of photons. The frequency and movement direction of the photons are related to the characteristics of the laser itself.

[0101] The smoke particle scattering photon module determines the scattering direction of photons scattered by collision with smoke particles during travel, based on the current state of the smoke particles, by calculating the intensity distribution of Mie scattering and combining it with a generated random number. Photons may collide with smoke particles during travel. Once a collision occurs, the photons will be scattered. The probability distribution of the scattering angle and scattering azimuth angle obeys the Mie scattering law. The scattering direction of the photons is determined by calculating the intensity distribution of Mie scattering and combining it with the generated random number. The same photon may be scattered multiple times during travel.

[0102] The detector receives the photon module, which receives photons that meet the constraints of the detector's own characteristics according to the detector's own characteristics.

[0103] Combine Figure 2 A method for simulating infrared laser scattering by smoke screen based on a diffusion model includes the following steps:

[0104] Step 1: Simulate the smoke diffusion process and input physical constants and external environmental parameters. The physical constants include the speed of light in a vacuum, gravitational acceleration, and the Boltzmann constant. The external environmental parameters include temperature, humidity, and air pressure.

[0105] Step 2: inputting the spatial position information of the smoke generating device and smoke generating related parameters; the smoke generating related parameters include the size parameters of the smoke generating nozzle and the flow rate of the smoke generating nozzle;

[0106] Step 3: Input relevant parameters of the smoke agent, including particle size distribution, refractive index and density;

[0107] The particle size distribution of the smoke agent satisfies the Rosin-Rammler cumulative distribution function:

[0108]

[0109] Where d is the particle size, is the average particle size, n is the particle size distribution index;

[0110] Step 4: Set the time granularity of the diffusion process simulation, that is, the time step corresponding to one cycle execution and the total time length of the diffusion process simulation;

[0111] Step 5: The smoke generating device generates smoke particles and adds status information of the smoke particles to a smoke particle status information table; the status information of the smoke particles includes position, speed, particle size, refractive index, density, etc.;

[0112] Step 6: Calculate the external forces acting on the smoke particles, including gravity, buoyancy, air resistance, etc., and then calculate the random motion of the smoke particles interacting with air particles. Update the position and velocity information of the smoke particles under these forces into the existing particle state information table.

[0113] Step 7: Count the collision information between smoke particles and determine whether the condensation condition is met. If the condensation condition is met, calculate the state information of the new particle and update it to the state information table, and delete the state information of the corresponding particle before the collision. If the condensation condition is not met, calculate the speed of each particle after the collision and update the new speed information to the state information table. Finally, increase the diffusion process simulation time by one diffusion process time step.

[0114] Step 8: Check whether the current simulation time reaches the total time length. If it reaches the total time length, go to step 9 to simulate the smoke scattering process; if it does not reach the total time length, return to step 5 and perform the simulation process of the next time step;

[0115] Step 9: Input the spatial position information of the laser and the relevant parameters of the laser, including the operating wavelength, beam divergence angle, etc.

[0116] Step 10: Input the spatial position information of the detector and related parameters of the detector, including receiving radius, receiving field of view, etc.

[0117] Step 11: setting the number of emitted photons, the time granularity of the scattering process simulation, and the time length of the scattering process simulation, and setting the counts of emitted photons and received photons to zero respectively;

[0118] Step 12: The laser emits a photon, records the position and direction of the photon, adds 1 to the emitted photon count, and determines whether the emitted photon count is greater than the set number of emitted photons. If so, proceed to step 16; if not, proceed to step 13.

[0119] Step 13: Calculate the new position of the photon after one time step, update the position information of the photon, and determine whether the photon has reached the detector. If the photon has reached the detector, proceed to step 15; if the photon has not reached the detector, proceed to step 14;

[0120] Step 14: Look up the smoke particle state information table to determine whether the photon collides with the smoke particle. If a collision occurs, calculate the spatial distribution of the Mie scattering intensity and determine the scattering direction of the photon based on the generated random number, and update the photon's motion direction information. If no collision occurs, do nothing. Finally, increase the scattering process simulation time by one scattering process time step, and return to step 13.

[0121] The calculation of the spatial distribution of the Mie scattering intensity and the determination of the scattering direction of the photon in combination with the generated random number are as follows:

[0122] Since the incident light is unpolarized natural light, the Mie scattered light intensity has the following spatial distribution:

[0123]

[0124] Where, I λ is the scattered light intensity, that is, the energy per unit area per unit time; I 0，λ is the incident light intensity, that is, the energy per unit area per unit time; i1 is the intensity function of the horizontal polarization component of the scattered light, i2 is the intensity function of the vertical polarization component of the scattered light, λ is the wavelength of the incident light, χ = 2πr / λ is the particle size parameter, R is the distance between the observation point and the center of the particle, m is the refractive index of the particle relative to the surrounding medium, and θ is the angle between the scattered light and the incident light, that is, the scattering angle;

[0125] The mathematical expressions of i1 and i2 can be written as infinite series:

[0126]

[0127]

[0128] Where a n and b n is the amplitude function, all of which are complex numbers and are related to χ and m, but θ is independent of π; n and τ n is a function that is only related to the scattering angle θ; a n 、b n , π n and τ n The expressions are:

[0129]

[0130]

[0131]

[0132]

[0133] Where, ψ n and ζ n is a half-integer order Bessel function and a second-kind Hankel function, expressed as:

[0134]

[0135]

[0136] P n (cosθ) and are the Legendre functions and first-order associated Legendre functions with respect to cosθ.

[0137] Step 15: Determine whether the photon meets the constraints of the detector reception. If the constraints are met, the received photon count is increased by 1, and the process returns to step 12; if the constraints are not met, the received photon count remains unchanged, and the process returns to step 12;

[0138] Step 16: The simulation ends, and the ratio of the received photon count to the emitted photon count corresponds to the transmittance of the smoke screen.

[0139] The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A smoke screen scattering infrared laser simulation system based on a diffusion model, characterized in that: Including smoke diffusion process simulation subsystem and smoke scattering process simulation subsystem; The smoke diffusion process simulation subsystem includes four modules: smoke particle generation, smoke particle state information statistics, smoke particle interaction analysis, and smoke particle state transfer and state update. The smoke particle generation module sends the smoke particles into the simulation system by spraying them through the smoke generating device; The smoke particle state information statistics module measures and counts the state attributes of the smoke particles during their generation process; The smoke particle interaction analysis module analyzes and calculates the collision, coagulation and external force between smoke particles during the diffusion process; The smoke particle state transfer and state update module updates the state information of the smoke particles; The smoke scattering process simulation subsystem includes three modules: laser emitting photons, smoke particle scattering photons, and detector receiving photons: The laser emits a photon module. The laser emits laser light, which is considered to emit a large number of photons. The frequency and movement direction of the photons are related to the characteristics of the laser itself. The smoke particle scattering photon module determines the scattering direction of photons scattered by collision with smoke particles during their travel, based on the current state of the smoke particles, by calculating the intensity distribution of Mie scattering and combining it with the generated random number; The detector receives the photon module, which receives photons that meet the constraints of the detector's own characteristics according to the detector's own characteristics.

2. The smoke scattering infrared laser simulation system based on the diffusion model according to claim 1 is characterized in that: The smoke diffusion process simulation subsystem simulates the collision, coagulation and external force effects between smoke particles in actual environments.

3. The smoke scattering infrared laser simulation system based on the diffusion model according to claim 1 is characterized in that: The state properties of smoke particles during the generation process include smoke particle velocity, particle size, density and refractive index.

4. The smoke scattering infrared laser simulation system based on the diffusion model according to claim 3 is characterized in that: The state properties of smoke particles during the generation process are determined by the properties of the smoke agent itself, the characteristics of the smoke generating device and the environmental parameters.

5. The smoke scattering infrared laser simulation system based on the diffusion model according to claim 1 is characterized in that: The external forces acting on smoke particles during the diffusion process include gravity, buoyancy and air resistance.

6. The smoke scattering infrared laser simulation system based on the diffusion model according to claim 1 is characterized in that: The smoke particle state transfer and state update module updates the state information of the smoke particles, including the position, velocity and particle size information of the smoke particles after the interaction occurs.

7. A method for simulating infrared laser scattering by smoke based on a diffusion model, characterized in that: The following steps are involved: Step 1: Start the simulation, simulate the smoke diffusion process, and input physical constants and external environment parameters; Step 2: Input the spatial location information of the smoke generating device and smoke-related parameters; Step 3, input relevant parameters of the smoke agent; Step 4: Set the time granularity of the diffusion process simulation, that is, the time step corresponding to one cycle execution and the total time length of the diffusion process simulation; Step 5: The smoke generating device generates smoke particles and adds the status information of the smoke particles to the smoke particle status information table; Step 6: Calculate the external forces acting on the smoke particles, then calculate the random motions caused by the interaction between the smoke particles and the air particles, and update the position and velocity information of the smoke particles under these forces into the existing particle state information table; Step 7: Count the collision information between smoke particles and determine whether the condensation condition is met. If the condensation condition is met, calculate the state information of the new particle and update it to the state information table, and delete the state information of the corresponding particle before the collision. If the condensation condition is not met, calculate the speed of each particle after the collision and update the new speed information to the state information table. Finally, increase the diffusion process simulation time by one diffusion process time step. Step 8: Check whether the current simulation time reaches the total time length. If it reaches the total time length, go to step 9 to simulate the smoke scattering process; if it does not reach the total time length, return to step 5 and perform the simulation process of the next time step; Step 9: Input the spatial position information of the laser and the laser related parameters; Step 10: Input the spatial location information of the detector and related parameters of the detector; Step 11: setting the number of emitted photons, the time granularity of the scattering process simulation, and the time length of the scattering process simulation, and setting the counts of emitted photons and received photons to zero respectively; Step 12: The laser emits a photon, records the position and direction of the photon, adds 1 to the emitted photon count, and determines whether the emitted photon count is greater than the set number of emitted photons. If so, proceed to step 16; if not, proceed to step 13. Step 13: Calculate the new position of the photon after one time step, update the position information of the photon, and determine whether the photon has reached the detector. If the photon has reached the detector, proceed to step 15; if the photon has not reached the detector, proceed to step 14; Step 14: Look up the smoke particle state information table to determine whether the photon collides with the smoke particle. If a collision occurs, calculate the spatial distribution of the Mie scattering intensity and determine the scattering direction of the photon based on the generated random number, and update the photon's motion direction information. If no collision occurs, do nothing. Finally, increase the scattering process simulation time by one scattering process time step, and return to step 13. Step 15: Determine whether the photon meets the constraints of the detector reception. If the constraints are met, the received photon count is increased by 1, and the process returns to step 12; if the constraints are not met, the received photon count remains unchanged, and the process returns to step 12; Step 16: The simulation ends, and the ratio of the received photon count to the emitted photon count corresponds to the transmittance of the smoke screen.

8. The method for simulating infrared laser scattering by smoke based on a diffusion model according to claim 7, characterized in that: Relevant parameters of the smoke agent in step 3, including particle size distribution, refractive index and density; The particle size distribution of the smoke agent satisfies the Rosin-Rammler cumulative distribution function F d : Where d is the particle size, is the average particle size, and n is the particle size distribution index.

9. The method for simulating infrared laser scattering by smoke based on a diffusion model according to claim 7, characterized in that: The state information of the smoke particles in step 5 includes the external force, Brownian motion, collision and coagulation. The interaction process is added according to the actual situation, and the update method of the smoke particle state information table is adjusted.

10. The method for simulating infrared laser scattering by smoke based on a diffusion model according to claim 7, characterized in that: In step 14, the spatial distribution of the Mie scattering intensity is calculated and combined with the generated random number to determine the scattering direction of the photon, as follows: When the incident light is unpolarized natural light, the Mie scattered light intensity has the following spatial distribution: Where, I λ is the scattered light intensity, that is, the energy per unit area per unit time; I 0，λ is the incident light intensity, that is, the energy per unit area per unit time; i1 is the intensity function of the horizontal polarization component of the scattered light, i2 is the intensity function of the vertical polarization component of the scattered light, λ is the wavelength of the incident light, χ = 2πr / λ is the particle size parameter, R is the distance between the observation point and the center of the particle, m is the refractive index of the particle relative to the surrounding medium, and θ is the angle between the scattered light and the incident light, that is, the scattering angle; The mathematical expressions of i1 and i2 are written as infinite series: Where a n and b n is the amplitude function, all of which are complex numbers and are related to χ and m, but θ is independent of π; n and τ n is a function that is only related to the scattering angle θ; a n 、b n , π n and τ n The expressions are: Where, ψ n and ζ n is a half-integer order Bessel function and a second-kind Hankel function, expressed as: P n (cosθ) and are the Legendre functions and first-order associated Legendre functions with respect to cosθ.

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