Laser weapon thermal halo effect compensation method

Abstract

The invention discloses a laser weapon thermal halo effect compensation method, and relates to the field of laser weapons, and the method comprises the steps: firstly outputting a laser beam at a preset focal length through a laser weapon, and shooting a target object through an imaging system, so as to obtain a target object image; then, according to the target object image, calculating to obtain at least one thermal halo index characteristic value, and according to the thermal halo index characteristic value, calculating to obtain a thermal halo index; and finally, inputting the thermal halo index into a compensation mapping model, calculating to obtain a focal length compensation amount, and adjusting the focal length of the laser weapon according to the focal length compensation amount to realize thermal halo effect compensation, thereby realizing real-time detection and high-precision compensation of the thermal halo effect, and improving the striking efficiency of the laser weapon.

Description

Technical Field

[0001] This application relates to the field of laser weapons, and more particularly to a method for compensating for the thermal scintillation effect of laser weapons. Background Technology

[0002] Thermal coma is a nonlinear effect caused by the change in refractive index due to the heating of the air along the way when a high-power laser is transmitted through the atmosphere. This leads to beam divergence, deflection, and distortion, and is one of the core bottlenecks restricting the combat effectiveness of laser weapons.

[0003] Among the technologies related to thermal glare compensation for laser weapons, the main ones include adaptive optics and predictive modeling based on atmospheric parameters. However, both of these technologies suffer from low compensation accuracy. Summary of the Invention

[0004] The main purpose of this application is to provide a method for compensating for the thermal stun effect of laser weapons, aiming to solve the technical problem of low compensation accuracy in existing methods for compensating for the thermal stun effect of laser weapons.

[0005] To achieve the above objectives, this application proposes a method for compensating for the thermal coma effect of laser weapons, comprising: The laser weapon outputs a laser beam at a preset focal length and uses an imaging system to capture images of the target object to obtain an image of the target object; Based on the target object image, at least one thermal halo index feature value is calculated, and based on the thermal halo index feature value, the thermal halo index is calculated. The thermal coma index is input into the compensation mapping model to calculate the focal length compensation amount, and the focal length of the laser weapon is adjusted according to the focal length compensation amount to achieve thermal coma effect compensation.

[0006] In one embodiment, the observation path of the imaging system and the laser emission path of the laser weapon are the same optical path, or the optical axis of the imaging system is parallel to the laser beam direction of the laser weapon.

[0007] In one embodiment, the thermal coma index feature values ​​include a first thermal coma index feature value, a second thermal coma index feature value, and a third thermal coma index feature value; wherein, The first thermal halo index feature value is the thermal halo sensitive gradient energy value of a single frame target object image; The second thermal coma index characteristic value is the thermal coma sensitive frequency band energy ratio of a single frame target object image; The third thermal halo index feature value is the trend of thermal halo index change in a continuous multi-frame target object image.

[0008] In one embodiment, the compensation mapping model describes the correlation between the laser weapon's output power, strike range, thermal index, and focal length compensation. The step of inputting the thermal corona index into the compensation mapping model to calculate the focal length compensation includes: The thermal coma index, the output power of the laser weapon, and the strike distance are input into the compensation mapping model to calculate the focal length compensation amount.

[0009] In one embodiment, the step of inputting the thermal coma index into the compensation mapping model, calculating the focal length compensation amount, and adjusting the focal length of the laser weapon according to the focal length compensation amount to achieve thermal coma effect compensation includes: When the thermal coma index exceeds a preset thermal coma index threshold, the thermal coma index is input into a compensation mapping model to calculate the focal length compensation amount. The focal length of the laser weapon is then adjusted based on the focal length compensation amount to achieve thermal coma effect compensation; or, When the rate of change of the thermal coma index is greater than the preset threshold for the rate of change of the thermal coma index, the thermal coma index is input into the compensation mapping model to calculate the focal length compensation amount and adjust the focal length of the laser weapon according to the focal length compensation amount to achieve thermal coma effect compensation.

[0010] In one embodiment, adjusting the focal length of the laser weapon according to the focal length compensation amount includes: The focal length of the laser weapon is adjusted in a step-by-step manner until the thermal index after focal length adjustment meets the convergence condition.

[0011] In one embodiment, the method further includes: The parameters of the compensation mapping model are adjusted based on the heat wave index to update the compensation mapping model.

[0012] One or more technical solutions proposed in this application have at least the following technical effects: A method for compensating for the thermal coma effect of laser weapons is proposed. First, a laser weapon outputs a laser beam at a preset focal length, and an imaging system is used to capture an image of the target object. Then, based on the target object image, at least one thermal coma index feature value is calculated, and a thermal coma index is calculated based on the thermal coma index feature value. Finally, the thermal coma index is input into a compensation mapping model to calculate a focal length compensation amount, and the focal length of the laser weapon is adjusted according to the focal length compensation amount to achieve thermal coma effect compensation. This method realizes real-time detection and high-precision compensation of the thermal coma effect, improving the strike effectiveness of laser weapons. Attached Figure Description

[0013] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0015] Figure 1 A flowchart illustrating the first embodiment of the laser weapon thermal coma effect compensation method provided in this application; The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0016] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application. To better understand the technical solutions of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0017] Thermal coma is a nonlinear effect caused by the change in refractive index due to the heating of the air along the way when a high-power laser is transmitted through the atmosphere. This leads to beam divergence, deflection, and distortion, and is one of the core bottlenecks restricting the combat effectiveness of laser weapons.

[0018] Among the technologies related to thermal glare compensation for laser weapons, the main ones include adaptive optics and predictive modeling based on atmospheric parameters. However, both of these technologies suffer from low compensation accuracy.

[0019] Specifically, the principle of adaptive optics technology is to use a wavefront sensor to detect laser wavefront distortion in real time, and then use a deformable mirror for phase compensation. However, under strong turbulence and strong thermal halo conditions, the detection accuracy of the wavefront sensor will be significantly reduced, so ultimately; The principle of predictive modeling based on atmospheric parameters is to use multiple sensors to detect current environmental parameters, such as temperature, humidity, and visibility, and then use a pre-built theoretical model to calculate the thermal coma effect. Finally, the parameters of the laser weapon are adjusted to compensate for the thermal coma effect. However, the theoretical model has many simplified assumptions and differs greatly from the actual environment. In addition, it can generally only detect environmental parameters near the laser weapon and cannot respond to the dynamic changes of the target path environment in real time, resulting in low compensation accuracy.

[0020] This application provides a method for compensating for the thermal coma effect of a laser weapon. In the first embodiment of this laser weapon thermal coma effect compensation method, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the laser weapon thermal coma compensation method of this application. The laser weapon thermal coma compensation method may include steps S10 to S30: Step S10: Use a laser weapon to output a laser beam at a preset focal length and use an imaging system to photograph the target object to obtain an image of the target object.

[0021] It should be noted that the target image is an image that at least contains the area to be struck by the target object. This could be an image including both the background and the target object, or an image containing only the target object (extracted from the original image), or an image containing only the area to be struck by the target object. The imaging system can be a high-resolution optoelectronic imaging system, which can be installed coaxially or adjacent to the laser weapon to ensure maximum overlap between the observation path and the laser emission path.

[0022] Specifically, during the laser weapon's strike operation, an imaging system can be used to image the target object in the target area in real time to obtain an image of the target object.

[0023] In one feasible implementation, the observation path of the imaging system and the laser emission path of the laser weapon are the same optical path, or the optical axis of the imaging system is parallel to the laser beam direction of the laser weapon.

[0024] It should be noted that this setup ensures that the imaging beam and the laser beam experience the same thermal coma interference, thereby improving the accuracy of subsequent thermal coma compensation.

[0025] Step S20: Calculate at least one thermal halo index feature value based on the target object image, and calculate the thermal halo index based on the thermal halo index feature value.

[0026] It should be noted that the thermal coma index feature value refers to the parameter that can quantify the thermal coma effect. The thermal coma index is calculated based on one or more thermal coma index feature values. Calculating the thermal coma index using multiple thermal coma index feature values ​​can improve the accuracy of subsequent thermal coma effect compensation.

[0027] It should also be noted that the essence of the thermal coma effect is the thermal lensing effect. That is, in the laser transmission path, the air absorbs laser energy, the air temperature rises, the refractive index decreases, and a radial refractive index gradient is formed. This is equivalent to introducing a negative lens in the optical path, increasing the beam divergence angle. This not only causes radially symmetrical blurring of the image, but also seriously affects the quality of the imaging beam and laser beam as time accumulates. Therefore, the thermal coma effect can be quantified by one or more of the following: the thermal coma sensitive gradient energy value of a single frame of the target object image, the thermal coma sensitive frequency band energy ratio of a single frame of the target object image, and the thermal coma index variation trend of multiple consecutive frames of the target object image.

[0028] In one feasible implementation, the thermal halo index characteristic values ​​include a first thermal halo index characteristic value, a second thermal halo index characteristic value, and a third thermal halo index characteristic value; wherein, The first thermal halo index feature value is the thermal halo sensitive gradient energy value of a single frame target object image; The second thermal coma index characteristic value is the thermal coma sensitive frequency band energy ratio of a single frame target object image; The third thermal halo index feature value is the trend of thermal halo index change in a continuous multi-frame target object image.

[0029] It should be noted that the thermal halo sensitive gradient energy value is defined as the region energy of the medium gradient region in the target object image. In the spatial gradient features, the thermal halo effect mainly affects the edge information of medium intensity. The edge information of high intensity (such as the outline of the target object) and the edge information of low intensity (such as noise) are less affected by the thermal halo effect. Therefore, the thermal halo sensitive gradient energy value can be used as the feature value for quantifying the thermal halo index. The larger the thermal halo sensitive gradient energy value, the more obvious the thermal halo effect.

[0030] Specifically, the mathematical expression for the thermal corona-sensitive gradient energy value can be:

[0031] In the formula, E g Let G(i,j) represent the gradient energy value sensitive to thermal halo, and let T represent the gradient magnitude at image pixel (i,j). l T represents the lower limit of the gradient magnitude of pixels in the medium region, such as 30% of the total gradient magnitude. u This represents the upper limit of the gradient magnitude for pixels in the medium-range region, such as 70% of the total gradient magnitude. This indicates that the gradient magnitude is in the range [T]. l T u The number of pixels within the range.

[0032] In the frequency domain attenuation characteristics, the thermal corona effect preferentially attenuates high-frequency components while relatively preserving mid-frequency components. Therefore, the energy ratio of the thermal corona-sensitive frequency band can be used as a characteristic value for quantifying the thermal corona index to distinguish it from uniform defocusing blur.

[0033] Specifically, the mathematical expression for the energy ratio of the heat-sensitive frequency band can be:

[0034] In the formula, F s Indicates the energy ratio of the thermal corona-sensitive frequency band. R high Indicates the proportion of energy in the high-frequency band. R mid This indicates the proportion of energy in the mid-frequency band. R low Indicates the proportion of energy in the low-frequency band; The mathematical expressions for the energy proportion of each frequency band are as follows:

[0035] In the formula, R band express R high , R mid or R low F(u,v) represents the spectrum obtained by performing a Fourier transform on the target image.

[0036] In one specific implementation, the high-frequency band, mid-frequency band, and low-frequency band are divided according to the following ranges: High frequency band ; Mid-frequency band, ; Low frequency band ; In the formula, The radius represents the point where the frequency is highest.

[0037] In the temporal evolution characteristics, the thermal halo effect has a time cumulative property, and the ambiguity increases monotonically with time. The trend of thermal halo index change can be used to distinguish between thermal halo effect (continuous deterioration) and instantaneous disturbance.

[0038] Specifically, the trend of the heat halo index can be characterized by the slope of the trend. A positive slope indicates an increase in the heat halo index. Therefore, the mathematical expression for the trend of the heat halo index can be:

[0039] In the formula, trend Indicates the trend of heat wave index changes. TI [ i ] indicates the first i Thermal halo index of the target object image in the frame. N Indicates the size of the analysis window; in this embodiment, N Configured to 10~20 frames per second.

[0040] In one feasible implementation, step S20, "calculating the heat corona index based on the heat corona index characteristic value," may include steps S201-S202: Step S201: After calculating and obtaining the first thermal halo index feature value, the second thermal halo index feature value and the third thermal halo index feature value, normalize the first thermal halo index feature value, the second thermal halo index feature value and the third thermal halo index feature value respectively, and linearly map each feature value to the [0,1] interval. For feature values ​​that exceed the training set range, truncation is performed.

[0041] In this embodiment, the maximum and minimum value normalization method is adopted. Based on the maximum and minimum values ​​of each feature value in the training dataset during the offline calibration stage, the first thermal halo index feature value, the second thermal halo index feature value, and the third thermal halo index feature value are normalized respectively.

[0042] Step S202: The normalized first thermal halo index feature value, second thermal halo index feature value and third thermal halo index feature value are weighted and fused to calculate the thermal halo index.

[0043] Specifically, the mathematical expression for calculating the heat wave index can be:

[0044] In the formula, TI represents the thermal coma index, and a, b, and c represent weighting coefficients. In this embodiment, a is configured as 0.45, b as 0.3, and c as 0.25.

[0045] Step S30: Input the thermal coma index into the compensation mapping model, calculate the focal length compensation amount, and adjust the focal length of the laser weapon according to the focal length compensation amount to achieve thermal coma effect compensation.

[0046] It should be noted that by adjusting the focal length of the laser weapon, a positive lens effect opposite to the thermal coma effect is introduced to balance the wavefront distortion caused by the thermal coma effect, thereby compensating for the thermal coma effect, maintaining the quality of the laser beam, and improving the strike effectiveness.

[0047] In one feasible implementation, the compensation mapping model is a single-parameter extended model that describes the relationship between the thermal corona index and the focal length compensation amount.

[0048] It should be noted that laboratory calibration methods can be used to establish the correlation between the thermal corona index and the focal length compensation.

[0049] In one feasible implementation, the compensation mapping model describes the relationship between the output power, strike range, thermal index, and focal length compensation of a laser weapon.

[0050] Accordingly, step S30, "inputting the thermal corona index into the compensation mapping model and calculating the focal length compensation amount," may include step A1: Step A1: Input the thermal coma index, the output power of the laser weapon, and the strike distance into the compensation mapping model to calculate the focal length compensation amount.

[0051] It should be noted that the compensation mapping model in this embodiment is a multi-parameter extended model, which comprehensively considers the correlation between the thermal coma index, the output power of the laser weapon, the strike distance, and the focal length compensation.

[0052] It should also be noted that a laboratory calibration method can be used to establish a mapping model of thermal coma index, laser weapon output power, strike distance, and focal length compensation. Specifically, during calibration, under different output power, different strike distance, and different thermal coma index scenarios, by scanning different focal length settings, the spot quality indicators (such as Strehl ratio, circumferential energy, etc.) at the target object (e.g., target) are measured to determine the focal length compensation amount when the spot quality indicator is at its maximum, in order to construct a dataset.

[0053] After constructing the dataset, a compensation mapping model is established based on the dataset. The mathematical expression of the compensation mapping model can be:

[0054] In the formula, TI represents focal length compensation, L represents the thermal index, P represents the impact distance, and a0~a6 represent weighting coefficients.

[0055] It is understandable that the first implementation of the compensation mapping model provided above has higher computational efficiency for focal length compensation than the second implementation, thus the first implementation has higher compensation efficiency. Since the second implementation has higher accuracy for focal length compensation than the first implementation, the second implementation has a better effect on compensating for thermal halo effect and can also improve the adaptability of the model under different working conditions.

[0056] The above are only two feasible implementations of the compensation mapping model provided in this embodiment. This embodiment does not specifically limit the specific implementation of the compensation mapping model.

[0057] In one possible implementation, step S30 may include step S301 or S302: Step 301: When the thermal coma index is greater than the preset thermal coma index threshold, the thermal coma index is input into the compensation mapping model to calculate the focal length compensation amount and adjust the focal length of the laser weapon according to the focal length compensation amount to achieve thermal coma effect compensation.

[0058] Step S302: When the rate of change of the thermal corona index is greater than the preset threshold for the rate of change of the thermal corona index, the thermal corona index is input into the compensation mapping model to calculate the focal length compensation amount and adjust the focal length of the laser weapon according to the focal length compensation amount to achieve thermal corona effect compensation.

[0059] Specifically, when the heat halo index is greater than the heat halo index threshold, or the rate of change of the heat halo index is greater than the rate of change of the heat halo index threshold, a compensation command is output to initiate heat halo effect compensation. In this embodiment, the compensation command is configured as 1. When the heat halo index is less than the heat halo index threshold, and the rate of change of the heat halo index is less than or equal to the rate of change of the heat halo index threshold, a monitoring command is output, and no heat halo effect compensation is performed. In this embodiment, the monitoring command is configured as 0. The mathematical expression for the above judgment process can be:

[0060] In the formula, This represents the thermal halo index corresponding to the t-th frame image. Indicates the threshold of the heat wave index. This represents the rate of change of the thermal halo index corresponding to the t-th frame image. This represents the threshold for the rate of change of the heat wave index.

[0061] In one feasible implementation, step S30, "adjusting the focal length of the laser weapon according to the focal length compensation amount," may include step B1: The focal length of the laser weapon is adjusted in a step-by-step manner until the thermal index after focal length adjustment meets the convergence condition.

[0062] It should be noted that the focal length of the laser weapon is adjusted in a step-by-step manner in this embodiment to avoid overshoot; after each adjustment, the adjustment effect is evaluated to accurately control the amount of thermal compensation.

[0063] Specifically, after calculating the focal length compensation amount using the compensation mapping model, adjustments are made in small steps. The mathematical expression for the adjusted focal length is:

[0064] In the formula, f new Indicates the focal length to be configured, f current The current focal length is represented by , i represents the adjustment step, and α represents the caution coefficient. In this embodiment, α is configured as 0.25, and the step size is configured as 1, starting from 0 and increasing by one with each adjustment.

[0065] After each adjustment, the heat halo index after heat halo compensation is calculated using the adjusted target object image. The compensation effect is evaluated based on the difference between the heat halo index before and after heat halo compensation. Assuming the heat halo coefficient after heat halo compensation is... The thermal coma coefficient before thermal coma compensation is The difference in the heat coma index before and after heat coma compensation is: The mathematical expression is:

[0066] Then when If the value is greater than 0, the compensation is effective, and the thermal coma effect compensation continues until the convergence condition is met. In this embodiment, γ The configuration is set to 0.05.

[0067] when When the value is less than or equal to 0, the focal length is configured as the focal length of the previous thermal flare compensation configuration, and thermal flare compensation is stopped.

[0068] In one possible implementation, after step S30, the method further includes step S40: Step S40: Adjust the parameters of the compensation mapping model according to the thermal corona index to update the compensation mapping model.

[0069] Specifically, during the thermal coma compensation process, the thermal coma coefficient and its changes are continuously recorded to monitor the compensation effect. When the compensation effect is poor, such as when the model deviation is large, the model parameters are updated, such as one or more weight coefficients from a0 to a6, or the recursive least squares method, so that the compensation mapping model can adapt to environmental changes.

[0070] The laser weapon thermal flare effect compensation method in this embodiment first uses a laser weapon to output a laser beam at a preset focal length and uses an imaging system to capture an image of the target object. Then, based on the target object image, at least one thermal flare index feature value is calculated, and based on the thermal flare index feature value, a thermal flare index is calculated. By quantifying the thermal flare effect through the image feature value, complex wavefront detection and theoretical modeling are avoided. Based on millisecond-level processing of a single frame image, true real-time compensation can be achieved. In addition, the imaging system commonly equipped in existing laser weapons is reused, which greatly reduces the complexity and cost of the laser weapon system. Finally, the thermal flare index is input into the compensation mapping model to calculate the focal length compensation amount, and the focal length of the laser weapon is adjusted according to the focal length compensation amount to achieve thermal flare effect compensation. This achieves real-time detection and high-precision compensation of the thermal flare effect, improving the strike effectiveness of the laser weapon.

[0071] The above are only some embodiments of this application and do not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method for compensating for the thermal corona effect of a laser weapon, characterized in that, The method includes: The laser weapon outputs a laser beam at a preset focal length and uses an imaging system to capture images of the target object to obtain an image of the target object; Based on the target object image, at least one thermal halo index feature value is calculated, and based on the thermal halo index feature value, the thermal halo index is calculated. The thermal coma index is input into the compensation mapping model to calculate the focal length compensation amount, and the focal length of the laser weapon is adjusted according to the focal length compensation amount to achieve thermal coma effect compensation.

2. The laser weapon thermal coma compensation method as described in claim 1, characterized in that, The observation path of the imaging system and the laser emission path of the laser weapon are the same optical path, or the optical axis of the imaging system is parallel to the laser beam direction of the laser weapon.

3. The laser weapon thermal coma compensation method as described in claim 1, characterized in that, The thermal halo index characteristic values ​​include a first thermal halo index characteristic value, a second thermal halo index characteristic value, and a third thermal halo index characteristic value; wherein... The first thermal halo index feature value is the thermal halo sensitive gradient energy value of a single frame target object image; The second thermal coma index characteristic value is the thermal coma sensitive frequency band energy ratio of a single frame target object image; The third thermal halo index feature value is the trend of thermal halo index change in a continuous multi-frame target object image.

4. The laser weapon thermal coma compensation method as described in claim 1, characterized in that, The compensation mapping model describes the relationship between the output power, strike range, thermal index, and focal length compensation of a laser weapon. The step of inputting the thermal corona index into the compensation mapping model to calculate the focal length compensation includes: The thermal coma index, the output power of the laser weapon, and the strike distance are input into the compensation mapping model to calculate the focal length compensation amount.

5. The laser weapon thermal coma compensation method as described in claim 1, characterized in that, The step of inputting the thermal coma index into the compensation mapping model, calculating the focal length compensation amount, and adjusting the focal length of the laser weapon according to the focal length compensation amount to achieve thermal coma effect compensation includes: When the thermal coma index exceeds a preset thermal coma index threshold, the thermal coma index is input into a compensation mapping model to calculate the focal length compensation amount. The focal length of the laser weapon is then adjusted based on the focal length compensation amount to achieve thermal coma effect compensation; or, When the rate of change of the thermal coma index is greater than the preset threshold for the rate of change of the thermal coma index, the thermal coma index is input into the compensation mapping model to calculate the focal length compensation amount and adjust the focal length of the laser weapon according to the focal length compensation amount to achieve thermal coma effect compensation.

6. The laser weapon thermal coma compensation method as described in claim 1, characterized in that, The adjustment of the laser weapon's focal length based on the focal length compensation includes: The focal length of the laser weapon is adjusted in a step-by-step manner until the thermal index after focal length adjustment meets the convergence condition.

7. The laser weapon thermal coma compensation method as described in claim 1, characterized in that, The method further includes: The parameters of the compensation mapping model are adjusted based on the heat wave index to update the compensation mapping model.

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