Laser-corrected dual-band infrared target passive ranging method

Abstract

The invention provides a laser-corrected dual-band infrared passive distance measurement method, which comprises the following steps of: firstly, acquiring information of a target at three continuous sampling moments by using an infrared detection system, and estimating an extinction coefficient and path radiation; then calculating a multi-mode fusion distance at a next sampling moment; correcting a medium-wave extinction coefficient, medium-wave path radiation, a long-wave extinction coefficient and long-wave path radiation by using the field angles, the irradiance and the laser ranging values at the second to fourth sampling moments; and for a subsequent moment, calculating the multimode fusion distance of the target as a resolving value of the target distance at the sampling moment, and then correcting the medium wave extinction coefficient, the medium wave path radiation, the long wave extinction coefficient and the long wave path radiation. According to the method, dual-band infrared passive distance measurement and laser distance measurement are fused, target motion information is combined, accumulative errors of infrared passive distance measurement and a motion model are eliminated through laser correction, the defect of infrared distance measurement is compensated, the distance measurement precision and the distance measurement stability are improved on the premise of concealment, and multi-target real-time distance measurement is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoelectric detection and photoelectric countermeasure, and mainly relates to a laser-corrected dual-band infrared target passive ranging method, which can be used for real-time passive positioning of multiple targets in the air. BACKGROUND

[0002] Dual-band infrared passive ranging is a distance measurement technology without active signal emission, which estimates the distance of a target by detecting the difference in infrared radiation of the target at two different infrared bands, using atmospheric attenuation characteristics or radiation intensity ratio. Infrared passive ranging can still work at night or in low light conditions, and is easy to realize multi-target ranging, but the ranging accuracy is affected by target temperature, radiation intensity and environmental radiation, and the effect on cold targets or low infrared feature targets is poor, and the ranging accuracy decreases significantly with the increase of distance.

[0003] The obvious advantage of laser ranging is that the laser beam has strong directivity, small ranging error, strong long-distance ranging capability and strong anti-interference capability, which can reduce the influence of environmental light or electronic interference, but the disadvantage is that it is easy to be exposed and has poor adaptability to complex targets. It may fail to range transparent, strongly reflective or fast-moving targets. SUMMARY

[0004] In view of the problems existing in dual-band infrared passive ranging and laser ranging, the present application proposes a laser-corrected dual-band infrared passive ranging method, which combines dual-band infrared passive ranging with laser ranging, and combines target motion information, eliminates the cumulative error of infrared passive ranging and motion model through laser correction, compensates for the deficiency of infrared ranging, improves the ranging accuracy and stability under the premise of concealment, realizes real-time ranging of multiple targets, and is an advanced ranging scheme considering concealment, accuracy and anti-interference capability.

[0005] The technical scheme of the present application is as follows:

[0006] The laser-corrected dual-band infrared target passive ranging method comprises the following steps:

[0007] Step 1: using an infrared detection system to collect information of a target at three consecutive sampling times, and estimating the extinction coefficient and path radiation; the infrared detection system is a dual-band infrared detection system of mid-wave infrared and long-wave infrared; the information includes the azimuth angle, the elevation angle, the mid-wave image information and the long-wave image information of the target;

[0008] Step 2: calculating the multi-model fusion distance of the target at the 4th sampling time;

[0009] Step 3: bringing the opening angle, radiation intensity and laser ranging value at the 2nd to 4th sampling time into the formula

[0010]

[0011] correcting the mid-wave extinction coefficient μ M , the mid-wave path radiation E M_dis , the long-wave extinction coefficient μ L , and the long-wave path radiation E L_dis .

[0012] Step 4: for the subsequent time, using the method of step 2, calculating the multi-mode fusion distance of the target as the solution value of the target distance at this sampling time, and then using the method of step 3, correcting the mid-wave extinction coefficient μ M , the mid-wave path radiation E M_dis , the long-wave extinction coefficient μ L , and the long-wave path radiation E L_dis .

[0013] Further, in step 1, the specific process of estimating the extinction coefficient and the path radiation is as follows:

[0014] Step 1.1: determining the mid-wave target gray scale DN M (i), the long-wave target gray scale DN L (i), the mid-wave target area S M (i), and the long-wave target area S L (i) according to the mid-wave image information and the long-wave image information;

[0015] Step 1.2: using the mid-wave target gray scale DN M (i) and the long-wave target gray scale DN L (i), calculating the radiation brightness L M0 (i) at the optical entrance pupil of the mid-wave infrared and the radiation brightness L L0 (i) at the optical entrance pupil of the long-wave infrared according to the radiation scaling functions of the mid-wave infrared and the long-wave infrared, respectively;

[0016] Step 1.3: using the focal length f M and the aperture d M of the mid-wave infrared and the focal length f L and the aperture d L of the long-wave infrared, respectively, to determine the solid angle Ω M and Ω L relative to the imaging focal point at the optical entrance pupil of the mid-wave infrared and the long-wave infrared, respectively;

[0017] Step 1.4: according to the horizontal field of view FovH M of the mid-wave infrared, the radiation brightness L M0 of the target at the optical entrance pupil of the mid-wave infrared, the mid-wave target area S M (i), the horizontal field of view FovH L of the long-wave infrared, and the radiation brightness L L0 of the target at the optical entrance pupil of the long-wave infrared,, long-wave target area S L (i), respectively, determine the relative to the three consecutive time, the target equivalent to the circle area after the circle radius angle θ M (i) and relative to the long-wave infrared angle θ L (i), the target at the mid-wave infrared and long-wave infrared optical entrance pupil radiation E M (i), E L (i);

[0018] Step 1.5: the radiation obtained in step 1.4 combined with the target radiation brightness obtained by the infrared detection system to establish the equation, with the target movement, simultaneous equations at three consecutive sampling time, use numerical method to solve the mid-wave extinction coefficient μ M , mid-wave path radiation E M_dis , long-wave extinction coefficient μ L and long-wave path radiation E L_dis ;

[0019]

[0020] Further, in step 1.2, the radiation scaling function of mid-wave infrared and long-wave infrared is respectively:

[0021] DN M (i) = 1075.4 × L M0 (i) + 3882.7

[0022] DN L (i) = 409.38 × L L0 (i) + 1590.1.

[0023] Further, in step 1.3, the solid angle calculation formula is:

[0024]

[0025] Further, in step 1.4, according to the formula

[0026]

[0027] determine the angle θ M (i), θ L (i) and the radiation E M (i), E L (i).

[0028] Further, in step 2, the process of calculating the multi-mode fusion distance R'(4) of the target at the fourth sampling time is:

[0029] Step 2.1: Based on the medium-wave and long-wave infrared radiation measurement data of the target at the 3rd and 4th sampling moments, and the laser ranging value of the target relative to the observation point at the 3rd sampling moment, according to the formula

[0030]

[0031] R d =R(i)

[0032] Calculate the medium wave ranging value R of the target at the 4th sampling moment M (4) and the long-wave ranging value R L (4), where β(i) and ε(i) are the azimuth and elevation angles corresponding to the target at the i-th sampling moment;

[0033] Step 2.2: According to the formula

[0034]

[0035] Calculate the estimated motion distance R of the target at the 4th sampling moment Move (4);

[0036] Step 2.3: According to the formula

[0037]

[0038] Calculate the multi-model passive ranging fusion coefficient, where k1, k2, and k3 represent the fusion coefficients of the medium-wave ranging model, long-wave ranging model, and motion model in the passive ranging algorithm, respectively, and are updated with the target laser ranging value; R(i) is the laser ranging value at the i-th moment;

[0039] Step 2.4: According to the formula

[0040] R′(i+2)=k1R M (i+2)+k2R L (i+2)+k3R Move (i+2), i=2

[0041] Calculate the multimodal fusion distance R′(4) of the target at the 4th sampling time.

[0042] Furthermore, in step 4, if there is no laser ranging value calculated at the current sampling moment, the multi-model passive ranging fusion coefficient at the previous sampling moment is used as the multi-model passive ranging fusion coefficient at the current sampling moment. If there is a laser ranging value at the current sampling moment, the multi-model passive ranging fusion coefficient is updated, and the laser ranging value at the sampling moment is used as the solution value of the target distance at the sampling moment.

[0043] Further, if there are other targets in the same field of view, the same medium wave extinction coefficient mu is used to calculate the distance of other targets in the same field of view M , medium wave path radiation E M_dis , long wave extinction coefficient mu L , and long wave path radiation E L_dis , according to the azimuth, elevation angle, and irradiance intensity information of the remaining targets, the multi-mode fusion distance of the remaining targets in the same field of view is calculated in parallel; and the laser range finder corrects the distance of multiple targets in a single field of view in turn according to the search period.

[0044] Advantages

[0045] 1. The ranging model of the application not only realizes distance measurement of the target, but also intermittently corrects the ranging model and parameters by using laser distance, which not only ensures the concealment of passive ranging of multiple targets, but also improves the accuracy of passive ranging of multiple targets, and has high application prospect in military.

[0046] 2. The application realizes passive ranging by dual-band infrared, and calculates the target distance by combining the motion of the target, so as to reduce the calculation amount of the target calculation process, and ensure the real-time performance of the passive ranging method.

[0047] 3. The application also solves the problem that the laser cannot simultaneously measure the distance of multiple targets in the same field of view. The dual-band infrared passive ranging solves the problem that multiple targets are difficult to be measured in real time.

[0048] Additional aspects and advantages of the application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0049] The above and / or additional aspects and advantages of the application will become apparent and be readily understood from the following description, including the appended drawings, in which:

[0050] Figure 1 is a schematic diagram of the principle of dual-band infrared passive ranging corrected by laser;

[0051] Figure 2 is a system ranging flowchart;

[0052] Figure 3 is a fitting curve of the calibration model of the medium wave infrared detection system and test data;

[0053] Figure 4 is a fitting curve of the calibration model of the long wave infrared detection system and test data. DETAILED DESCRIPTION

[0054] Embodiments of the present application are described in detail below, which are exemplary and intended to explain the present application, and cannot be understood as a limitation of the present application.

[0055] The present embodiment proposes a laser-corrected dual-band infrared passive ranging method, and the experimental device used is as follows:

[0056] The measured target is set as an artificial target, and five targets are arranged at equal intervals to simulate the continuous motion state of the target in the t1-t5 period, wherein the target is at the target 1 position at the t1 moment, the target is at the target 2 position at the t2 moment, and so on.

[0057] The specific method flow is as shown in Figure 2 The specific method flow is as shown in

[0058] Step 1: Determine the observation point as the point where the infrared detection system is located, the infrared detection system is a dual-band infrared detection system of medium wave infrared and long wave infrared, and a medium wave thermal imager and a long wave thermal imager are built-in.

[0059] Use the infrared detection system to collect information of the target at three continuous sampling moments (i=1, 2, 3), and estimate the extinction coefficient and path radiation; the information includes the azimuth angle, the elevation angle, the medium wave image information and the long wave image information of the target.

[0060] The specific process is as follows:

[0061] Step 1.1: Determine the medium wave target gray scale DN M (i) and the long wave target gray scale DN L (i) of each moment according to the medium wave image information and the long wave image information. Step 1.2: Determine the medium wave target area S M (i) and the long wave target area S L (i) of each moment according to the medium wave image information and the long wave image information.

[0062] In the present embodiment, the information of the five targets is as follows: the target 1 is 793.499 m away, the azimuth angle is 63.310°, and the elevation angle is 0.115°; the target 2 is 704.194 m away, the azimuth angle is 59.594°, and the elevation angle is 0.172°; the target 3 is 619.489 m away, the azimuth angle is 54.877°, and the elevation angle is 0.216°; the target 4 is 540.183 m away, the azimuth angle is 48.715°, and the elevation angle is 0.259°; and the target 5 is 468.567 m away, the azimuth angle is 40.480°, and the elevation angle is 0.314°.

[0063] The imaging data of the targets relative to the observation point are shown in Table 1:

[0064] Table 1 Imaging data of targets relative to measurement point

[0065]

[0066] Step 1.2: Use the medium wave target gray scale DN M (i), the long wave target gray scale DN L (i), according to the radiation calibration function of the medium wave thermal imager and the long wave thermal imager, respectively calculate the radiation brightness L at the optical entrance pupil of the medium wave thermal imager M0 (i) and the radiation brightness L at the optical entrance pupil of the long wave thermal imager L0 (i);

[0067] In this embodiment, the radiation calibration functions of the medium wave thermal imager and the long wave thermal imager are respectively:

[0068] DN M (i) = 1075.4 x L M0 (i) + 3882.7

[0069] DN L (i) = 409.38 x L L0 (i) + 1590.1

[0070] In this embodiment, the calibration models of the medium wave thermal imager and the long wave thermal imager and the fitting curves of the test data are respectively as shown in Figure 3 , Figure 4 From the target 1, target 2, target 3 in the Figure 3 , the radiation brightness at the optical entrance pupil of the medium wave thermal imager is respectively 1.0983, 1.0646, 1.0537; from the target 1, target 2, target 3 in the Figure 4 , the radiation brightness at the optical entrance pupil of the long wave thermal imager is respectively 13.5796, 13.0989, 13.1307.

[0071] Step 1.3: Use the focal length f M and aperture d M of the medium wave thermal imager and the focal length f L and aperture d L of the long wave thermal imager to respectively determine the solid angle Ω M , Ω L of the optical entrance pupil of the medium wave thermal imager and the long wave thermal imager relative to the imaging focus point;

[0072] In this embodiment, the solid angle calculation formula is:

[0073]

[0074] In this embodiment, Ω M = 0.1655, Ω L = 0.1888 are measured.

[0075] Step 1.4: According to the horizontal field of view FovH M, the radiation brightness L of the target at the optical entrance pupil of the medium-wave thermal imager M0 , medium wave target area S M (i) Horizontal field of view (FovH) of the long-wave thermal imager L , the radiation brightness L of the target at the optical entrance pupil of the long-wave thermal imager L0 , long wave target area S L (i) Determine the angle θ of the circle radius after the target is equivalent to the circle area relative to the medium wave thermal imager at three consecutive moments. M (i) and the aperture angle θ relative to the long-wavelength thermal imager L (i) Radiant illumination E of the target at the optical entrance pupil of the medium-wave thermal imager and the long-wave thermal imager M (i) E L (i);

[0076]

[0077] In this embodiment, the angle θ of the circle radius relative to the medium wave thermal imager after the target is equivalent to the circle area at three consecutive moments is determined respectively. M (1) = 0.021, θ M (2) = 0.0258, θ M (3) = 0.0305; relative to the long-wave thermal imager angle θ L (1) = 0.017, θ L (2) = 0.0208, θ L (3) = 0.0238; the radiant illumination E of the target at the entrance pupil of the medium-wave thermal imager at three consecutive moments M (1) = 4.4924 × 10 -3 w / cm 2 、E M (2) = 6.5049 × 10 -3 w / cm 2 、E M (3) = 8.9928 × 10 -3 w / cm 2 The radiant illumination E of the target at the entrance pupil of the long-wave thermal imager for three consecutive moments L (1) = 3.9518 × 10 -2 w / cm 2 、E L (2) = 5.1884 × 10 -2 w / cm 2 、E L (3) = 6.7932 × 10 -2 w / cm 2 .

[0078] Step 1.5: Establish equations with the irradiance obtained in step 1.4 and the target radiance obtained by the infrared detection system, and solve the equations by numerical method to obtain the middle wave extinction coefficient μ M , the middle wave path radiation E M_dis , the long wave extinction coefficient μ L , and the long wave path radiation E L_dis .

[0079]

[0080] wherein R(1), R(2), R(3) are the laser ranging values of the target at three sampling time points relative to the observation point; L M is the middle wave radiance of the target; L L is the long wave radiance of the target.

[0081] In this embodiment, the middle wave extinction coefficient μ M = 3.6366 x 10 -4 m -1 , the middle wave path radiation E M_dis = 5.3604 x 10 -8 w / m 2 , the long wave extinction coefficient μ L = 6.8730 x 10 -4 m -1 , and the long wave path radiation E L_dis = 8.1920 x 10 -7 w / m 2 are obtained by numerical method.

[0082] Step 2: Calculate the multi-mode fusion distance R'(4) of the target at the fourth sampling time point by the following process:

[0083] Step 2.1: According to the middle wave and long wave infrared radiation measurement data of the target at the third and fourth sampling time points, and the laser ranging value of the target at the third sampling time point relative to the observation point, calculate the middle wave ranging value R M (4) = 576.1819 m and the long wave ranging value R L (4) = 531.4460 m at the fourth sampling time point according to the formula

[0084]

[0085] R d = R(i)

[0086] , wherein β(i), ε(i) are the azimuth angle and the pitch angle of the target at the i sampling time point; the process of calculating the middle wave ranging value is referred to as algorithm 1, and the process of calculating the long wave ranging value is referred to as algorithm 2.

[0087] Step 2.2: According to the formula

[0088]

[0089] Calculate the motion estimation distance R of the target at the 4th sampling moment Move (4) = 542.4396 m; the process of calculating the motion estimation distance is referred to as algorithm 3.

[0090] Step 2.3: According to the formula

[0091]

[0092] Calculate the multi-model passive ranging fusion coefficient, where k1, k2, and k3 represent the fusion coefficients of the medium wave ranging model, the long wave ranging model, and the motion model in the passive ranging algorithm, respectively, and are updated with the target laser ranging value; R(i) is the laser ranging value at the ith moment.

[0093] In this embodiment, there is a laser ranging value at the 3rd moment, so the multi-model passive ranging fusion coefficients k1 = 0.1310, k2 = 0.2138, and k3 = 0.6552 are calculated at the 3rd moment.

[0094] For the 4th moment, if there is no laser ranging value at the 4th moment, the multi-model passive ranging fusion coefficients of the last sampling moment are used as the multi-model passive ranging fusion coefficients of the current sampling moment; if the laser ranging value at the 4th moment is 540.183 m, the multi-model passive ranging fusion coefficients k1 = 0.0475, k2 = 0.1955, and k3 = 0.7570 are updated.

[0095] Step 2.4: According to the formula

[0096] R'(i+2) = k1R M (i+2) + k2R L (i+2) + k3R Move (i+2), i = 2

[0097] Calculate the multi-model fusion distance R'(4) of the target at the 4th sampling moment.

[0098] In this embodiment, if there is no laser ranging value at the 4th moment, R'(4) = 544.5114 m is calculated, and if there is a laser ranging value at the 4th moment, R'(4) = 541.8913 m is calculated.

[0099] Step 3: Bring the opening angle, radiant intensity, and laser ranging value of the 2nd to 4th sampling moments into the formula

[0100]

[0101] corrected mid-wave extinction coefficient μ M , mid-wave path radiance E M_dis , long-wave extinction coefficient μ L , and long-wave path radiance E L_dis .

[0102] corrected mid-wave extinction coefficient μ M = 3.6365 x 10 -4 m -1 , mid-wave path radiance E M_dis = 5.0236 x 10 -8 w / m 2 , long-wave extinction coefficient μ L = 6.8730 x 10 -4 m -1 , and long-wave path radiance E L_dis = 7.2293 x 10 - 7 w / m 2 .

[0103] Step 4: for the subsequent time, the value of i is updated, the multi-model fusion distance of the target is calculated as the solution of the target distance at the sampling time by the method of step 2, and the mid-wave extinction coefficient μ M , the mid-wave path radiance E M_dis , the long-wave extinction coefficient μ L , and the long-wave path radiance E L_dis are corrected by the method of step 3; wherein if there is no laser ranging value at the sampling time, the multi-model passive ranging fusion coefficient at the last sampling time is used as the multi-model passive ranging fusion coefficient at the current sampling time, and if there is a laser ranging value at the sampling time, the multi-model passive ranging fusion coefficient is updated by the formula in step 2.3, and the laser ranging value at the sampling time is used as the solution of the target distance at the sampling time.

[0104] For example, for the 5th sampling time, i = 3, the mid-wave ranging value R M (5) = 433.7163 m and the long-wave ranging value R L (5) = 478.3907 m of the target at the 5th sampling time are calculated by the method of step 3, and the motion estimation distance R Move (5) = 468.2729 m; if there is no laser ranging value at the 5th time, the multi-model passive ranging fusion coefficient at the last sampling time is used as the multi-model passive ranging fusion coefficient at the current sampling time, and R'(5) = 466.7576 m is calculated, and if there is a laser ranging value at the 5th time, the multi-model passive ranging fusion coefficient is updated, and R'(5) = 468.6164 m is calculated, and then the extinction coefficient and the path radiance are corrected. The corrected mid-wave extinction coefficient μM = 3.6365 x 10 -4 m -1 , the middle wave path radiation E M_dis = 3.8777 x 10 -8 w / m 2 , the long wave extinction coefficient μ L = 6.8729 x 10 -4 m -1 , and the long wave path radiation E L_dis = 6.6203 x 10 -7 w / m 2 .

[0105] The target distance is compared with the distance error output by the ranging algorithm as follows:

[0106] The real distance of target 4 is 540.183 m, the fusion distance based on the fusion coefficient of multi-model passive ranging at the 3rd moment is 544.5114 m, and the relative error is 0.80%.

[0107] The real distance of target 5 is 468.567 m, the fusion distance based on the fusion coefficient of multi-model passive ranging at the 4th moment is 466.7576 m, and the relative error is 0.386%.

[0108] If there are other targets in the same field of view, the same middle wave extinction coefficient μ M , the middle wave path radiation E M_dis , the long wave extinction coefficient μ L , and the long wave path radiation E L_dis are used to calculate the multi-model fusion distance of the remaining targets in the same field of view according to the azimuth angle, the elevation angle, and the irradiance information of the remaining targets; and the laser range finder corrects the distance of multiple targets in a single field of view in turn according to the search period.

[0109] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements, and variations to the above embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. A laser-corrected dual-band infrared target passive ranging method, characterized by: The following steps are involved: Step 1: Using an infrared detection system to collect information about the target at three consecutive sampling moments and estimate the extinction coefficient and path radiation; the infrared detection system is a dual-band infrared detection system of medium-wave infrared and long-wave infrared; the information includes the azimuth angle, pitch angle, medium-wave image information, and long-wave image information of the target; Step 2: Calculate the multimodal fusion distance of the target at the fourth sampling moment; Step 3: Substitute the angular range, irradiance, and laser ranging values ​​from the 2nd to the 4th sampling moments into the formula Corrected MW extinction coefficient μ M , Medium wave path radiation E M_dis , long-wave extinction coefficient μ L and the longwave path radiation E L_dis ; Step 4: For subsequent moments, use the method in step 2 to calculate the multi-mode fusion distance of the target as the solution value of the target distance at the sampling moment, and then use the method in step 3 to correct the medium-wave extinction coefficient μ M , Medium wave path radiation E M_dis , long-wave extinction coefficient μ L and the longwave path radiation E L_dis .

2. The laser-corrected dual-band infrared target passive ranging method according to claim 1, characterized in that: In step 1, the specific process of estimating the extinction coefficient and path radiation is: Step 1.1: Determine the medium wave target grayscale DN at each moment based on the medium wave image information and the long wave image information M (i) Long-wave target grayscale DN L (i) Medium wave target area S M (i) and the long-wave target area S L (i); Step 1.2: Using the Medium Wave Target Grayscale DN M (i) Long-wave target grayscale DN L (i) Calculate the radiance L at the mid-wave infrared optical entrance pupil based on the mid-wave infrared and long-wave infrared radiation calibration functions. M0 (i) and the radiance L at the long-wave infrared optical entrance pupil L0 (i); Step 1.3: Using the focal length f of the MWIR M and caliber d M , focal length f of long-wave infrared L and caliber d L Determine the solid angle Ω at the mid-wave infrared and long-wave infrared optical entrance pupil relative to the imaging focus M ,Ω L ; Step 1.4: Based on the horizontal field of view FovH of the MWIR M , the target's radiant brightness L at the entrance pupil of the medium-wave infrared optics M0 , medium wave target area S M (i) Horizontal field of view (FovH) of long-wave infrared L , the radiation brightness L of the target at the long-wave infrared optical entrance pupil L0 , long wave target area S L (i) Determine the angle θ of the circle radius relative to the mid-wave infrared after the target is equivalent to the circle area at three consecutive moments. M (i) and the angle θ relative to the long-wave infrared L (i) Radiant illumination E of the target at the entrance pupil of the mid-wave infrared and long-wave infrared optics M (i) E L (i); Step 1.5: Use the radiance obtained in step 1.4 and the target radiance obtained by the infrared detection system to establish an equation. As the target moves, combine the equations for three consecutive sampling moments and use numerical solutions to calculate the medium-wave extinction coefficient μ. M , Medium wave path radiation E M_dis , long-wave extinction coefficient μ L and the longwave path radiation E L_dis ; 3. The laser-corrected dual-band infrared target passive ranging method according to claim 2, characterized in that: In step 1.2, the radiation calibration functions for medium-wave infrared and long-wave infrared are: DN M (i)=1075.4×L M0 (i)+3882.7 DN L (i)=409.38×L L0 (i)+1590.1。 4. The laser-corrected dual-band infrared target passive ranging method according to claim 2, characterized in that: In step 1.3, the solid angle calculation formula is:

5. The laser-corrected dual-band infrared target passive ranging method according to claim 2, characterized in that: In step 1.4, according to the formula Determine the opening angle θ M (i), θ L (i) and irradiance E M (i) E L (i).

6. The laser-corrected dual-band infrared target passive ranging method according to claim 1, characterized in that: In step 2, the process of calculating the multi-mode fusion distance R′(4) of the target at the fourth sampling time is: Step 2.1: Based on the medium-wave and long-wave infrared radiation measurement data of the target at the 3rd and 4th sampling moments, and the laser ranging value of the target relative to the observation point at the 3rd sampling moment, according to the formula Calculate the medium wave ranging value R of the target at the 4th sampling moment M (4) and the long-wave ranging value R L (4), where β(i) and ε(i) are the azimuth and elevation angles corresponding to the target at the i-th sampling moment; Step 2.2: According to the formula Calculate the estimated motion distance R of the target at the 4th sampling moment Move (4); Step 2.3: According to the formula Calculate the multi-model passive ranging fusion coefficient, where k1, k2, and k3 represent the fusion coefficients of the medium-wave ranging model, long-wave ranging model, and motion model in the passive ranging algorithm, respectively, and are updated with the target laser ranging value; R(i) is the laser ranging value at the i-th moment; Step 2.4: According to the formula R′(i+2)=k1R M (i+2)+k2R L (i+2)+k3R Move (i+2),i=2 Calculate the multimodal fusion distance R′(4) of the target at the 4th sampling time.

7. The laser-corrected dual-band infrared target passive ranging method according to claim 1, characterized in that: In step 4, if there is no laser ranging value calculated at the current sampling moment, the multi-model passive ranging fusion coefficient at the previous sampling moment is used as the multi-model passive ranging fusion coefficient at the current sampling moment. If there is a laser ranging value at the current sampling moment, the multi-model passive ranging fusion coefficient is updated, and the laser ranging value at the sampling moment is used as the solution value of the target distance at the sampling moment.

8. The laser-corrected dual-band infrared target passive ranging method according to claim 1, characterized in that: If there are other targets in the same field of view, the same medium-wave extinction coefficient μ is used when calculating the distance of other targets in the same field of view. M , Medium wave path radiation E M_dis , long-wave extinction coefficient μ L and the longwave path radiation E L_dis , the multi-mode fusion distance of the remaining targets in the same field of view is solved in parallel according to the azimuth, pitch angle, and radiant illumination information of the remaining targets; and the laser rangefinder corrects the distances of multiple targets in a single field of view in sequence according to the search cycle.

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