Infrared radiation measuring instrument measures the infrared radiation of air target and retrieves method

Abstract

The present application belongs to the technical field of equipment calibration inversion, and particularly relates to an infrared radiation measurement instrument measurement of an aerial target infrared radiation inversion method. The method comprises: using an infrared radiation measurement instrument to measure the response gray scale and background gray scale of an aerial target; calculating and correcting the long-range atmospheric radiation by an atmospheric correction subsystem; calculating the atmospheric transmittance by the atmospheric correction subsystem; based on a linear response model, the target response gray scale is compensated after the long-range atmospheric radiation is subtracted from the background gray scale, and the target radiation is calculated, thereby completing the target radiation inversion. The method of the present application is changed from removing the long-range atmospheric radiation in front of the target to compensating the long-range atmospheric radiation behind the target, and has higher accuracy. For high-altitude long-distance targets, especially for the infrared radiation inversion accuracy of targets outside the atmosphere, the present application is more advantageous.

Description

Technical Field

[0001] This invention belongs to the field of equipment calibration and inversion technology, and in particular relates to an infrared radiation inversion method for measuring the infrared radiation of aerial targets using an infrared radiation measuring instrument. Background Technology

[0002] Currently, linear models are used to invert the radiation of targets in the infrared radiation measurement of aerial targets. This requires calibration of the equipment's response slope and intercept. In particular, the calibration of the intercept usually requires a large-diameter blackbody and a large-diameter collimator, which is costly and bulky, causing considerable inconvenience for field use. At the same time, atmospheric correction is the main source of error in the infrared radiation measurement of targets. Especially for weak targets, atmospheric path radiation will cause even greater errors, which need to be corrected. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and to propose an infrared radiation inversion method for measuring the infrared radiation of aerial targets using an infrared radiation measuring instrument.

[0004] To achieve the above objectives, this invention proposes a method for infrared radiation inversion of aerial targets using an infrared radiation measuring instrument, the method comprising:

[0005] The response grayscale and background grayscale of aerial targets were measured using an infrared radiation meter.

[0006] The atmospheric correction subsystem collects, calculates, and corrects the downstream atmospheric radiation.

[0007] Atmospheric transmittance is collected and calculated by the atmospheric correction subsystem;

[0008] Based on the linear response model, the target response grayscale is processed by subtracting the background grayscale and then compensating for the subsequent atmospheric radiation to calculate the target radiation, thus completing the target radiation inversion.

[0009] As an improvement to the above method, the step of measuring the response grayscale of an aerial target using an infrared radiation measuring instrument includes:

[0010] The response grayscale D of aerial targets was measured using an infrared radiation meter. nR and background grayscale D sc .

[0011] As an improvement to the above method, the step of collecting, calculating, and correcting the downstream atmospheric radiation by the atmospheric correction subsystem includes:

[0012] Step 3-1) Use an infrared radiation measurement device to collect the grayscale of the sky radiation response of a certain pixel of the camera at two pointing angles;

[0013] Step 3-2) The atmospheric correction subsystem is used to measure and calculate the sky radiation corresponding to the two pointing angles.

[0014] Step 3-3) Using the two sets of sky radiation response grayscale and sky radiation obtained in Step 3-1) and Step 3-2), the slope of the change in the sky response of the equipment is calculated, and then the atmospheric radiation in the later stage is obtained.

[0015] As an improvement to the above method, step 3-1) includes:

[0016] The sky radiative response grayscale of a certain pixel of the camera is repeatedly collected using an infrared radiation measurement device at the first pointing angle. After smoothing and calculating the collected data from multiple frames, the first sky radiative response grayscale D corresponding to the first pointing angle is obtained. s1 ;

[0017] The sky radiative response grayscale of a certain pixel of the camera is repeatedly collected using an infrared radiation measurement device at the second pointing angle. After smoothing and calculating the collected data from multiple frames, the second sky radiative response grayscale D corresponding to the second pointing angle is obtained. s2 .

[0018] As an improvement to the above method, step 3-2) includes:

[0019] Based on the atmospheric parameters collected by the atmospheric correction subsystem at the corresponding first pointing angle, the atmospheric path radiation L" between the target and the infrared radiation measurement device at the corresponding first pointing angle is calculated. qc1 and subsequent radiation L" hc1 Based on this, the first sky radiation L" was calculated. s1 ;

[0020] Based on the atmospheric parameters collected by the atmospheric correction subsystem at the corresponding second pointing angle, the atmospheric path radiation L" between the target and the infrared radiation measurement device at the corresponding second pointing angle is calculated. qc2 and subsequent radiation L" hc2 The second sky radiation L" was calculated. s2 .

[0021] As an improvement to the above method, the first sky radiation L" s1 Satisfy the following formula:

[0022] L″ s1 =L″ qc1 +L″ hc1

[0023] Second sky radiation L" s2 Satisfy the following formula:

[0024] L″ s2 =L″ qc2 +L″hc2 .

[0025] As an improvement to the above method, step 3-3) includes:

[0026] The atmospheric path radiation ratio correction factor γ is obtained according to the following formula:

[0027]

[0028] Where K is the coefficient of the pre-calibrated linear response model;

[0029] This leads to the slope K of the device's sky response change. as for:

[0030]

[0031] The calculated value L" obtained by combining the atmospheric correction subsystem hc The atmospheric radiation L in the later stages can be obtained from the following formula. hc :

[0032]

[0033] As an improvement to the above method, the target response grayscale, based on the linear response model, is calculated by subtracting the background grayscale and then compensating for the subsequent atmospheric radiation to obtain the target radiation, thereby completing the target radiation inversion; including:

[0034] Based on the coefficients K of the pre-calibrated linear response model, the atmospheric transmittance τ of the atmospheric correction subsystem is calculated. a Combined with the grayscale response of aerial targets D nR and background grayscale D sc And subsequent atmospheric radiation L hc From the following formula, the target radiation L is obtained. R Thus, the target radiation inversion is completed:

[0035]

[0036] Compared with the prior art, the advantages of the present invention are:

[0037] 1. The method of the present invention obtains the sky radiation response along with the target tracking measurement and uses it to correct the atmospheric path radiation, without the need for separate atmospheric path radiation correction measurement;

[0038] 2. The inversion method changes the original method of removing atmospheric path radiation in front of the target to background reduction processing and then compensating for atmospheric path radiation behind the target. This is more advantageous for improving the accuracy of infrared radiation inversion for high elevation angle long-distance targets, especially targets outside the atmosphere.

[0039] 3. The infrared target radiation measurement elements of this inversion method do not include the intercept of the pixel response. Only the K value of the linear response model is used for the parameters of the equipment itself. Therefore, when calibrating the equipment, only the response scaling factor K of the equipment needs to be calibrated, and the intercept no longer needs to be calibrated, which solves the previous problem of intercept calibration and reduces calibration costs. Attached Figure Description

[0040] Figure 1 This is a flowchart of the infrared radiation inversion method for measuring aerial targets using an infrared radiation measuring instrument according to the present invention;

[0041] Figure 2 The slope K of the device's sky response change as Schematic diagram of value measurement. Detailed Implementation

[0042] I. Calibration of the basic model

[0043] For a pixel n of an infrared radiation measuring camera, receiving infrared radiation L, the response curve approximates a straight line when the response grayscale value is within a certain range. Its linear response model is as follows:

[0044] D n =KL+c (1)

[0045] Among them, D n denoted as the overall response gray value of the band, L as the band or equivalent full-aperture radiance, K as the radiance response coefficient of the pixel, and c as the response gray value at zero input.

[0046] II. Atmospheric Radiation Correction in the Later Stages

[0047] (1) Equation for measuring sky radiation

[0048] When infrared radiation measurement equipment operates at full aperture, it tracks and measures the target. Other pixels besides the target pixel acquire sky radiation, which can be equivalently transformed to the target pixel response through calibration data.

[0049] For measurements taken over two airspace regions with similar angles, the sky radiance does not change significantly. Assuming their responses fall within the same linear segment, we have:

[0050]

[0051] Among them, L s1 L s2 The radiance at two different locations in the sky, D s1 D s2 These are the measurement device responses in two spatial domains, where K is the response coefficient of the linear model and c is the grayscale value of the zero-input response.

[0052] (2) Atmospheric path radiation correction

[0053] Considering that sky radiation is equivalent to the path radiation of the entire atmosphere, at the target location, the sky path radiation L s The path radiation L is divided into target-to-device path. p Atmospheric radiation L at a distance from the target hc (abbreviated as atmospheric backcourse radiation), has

[0054]

[0055] Among them, Ls, L p L hc and L" s 、L" p 、L" hc These are the measured values ​​of sky radiation, atmospheric path radiation, and atmospheric backpath radiation, respectively, and the calculated values ​​of the atmospheric correction subsystem.

[0056] Under normal circumstances, the atmosphere is homogeneous in all directions. When the elevation angle is the same or similar, the ratio of atmospheric path radiation variation along each path is assumed to be the same. Atmospheric path radiation can be corrected using a proportional model.

[0057]

[0058] Where γ is the path radiation ratio correction factor.

[0059] Substituting equations (2) and (3) into equation (4) and further refining, we obtain the path radiation ratio correction factor:

[0060]

[0061] Substituting equation (5) into equation (4) and rearranging, we obtain the corrected atmospheric back-range radiation:

[0062]

[0063] in, The slope of the device's sky response change.

[0064] like Figure 2 Since the sky radiative response grayscale values ​​at continuous elevation angles can be obtained during target tracking, a continuous sky radiative angle-response grayscale curve can be plotted. Each elevation angle can be calculated using the atmospheric correction subsystem to obtain a sky radiative value, thus allowing the plotting of the sky radiative calculation value-response grayscale curve at that elevation angle 'a'. Therefore, the slope of the curve at that elevation angle 'a' is K. as .

[0065] III. Infrared radiation calibration and target radiation inversion

[0066] The linear response model is used to describe the radiation response of a pixel n to an aerial target. The measurement equation is as follows:

[0067] D nR =KL R τ a +KL c +c (7)

[0068] Among them, L R For target radiation, L c For atmospheric path radiation (atmospheric radiation between the target and the equipment), τ a Atmospheric transmittance (atmospheric transmittance between the target and the equipment) D nR To measure the grayscale of the response.

[0069]

[0070] Equation (8) can be transformed and rewritten as follows:

[0071]

[0072] Among them, L s For the background radiation of the sky, L hc For later-stage atmospheric radiation. D sc =c+KL s The term is considered as a whole (other pixels besides the target pixel acquire sky radiation, which can be equivalently transformed to the target pixel response through calibration data). Then the target radiation L... R The inversion result is

[0073]

[0074] Substituting equation (6) into equation (10), and considering that the atmospheric transmittance of the target path cannot be obtained through measurement, the corrected calculated value is used.

[0075]

[0076] Among them, τ" a This is the calculated atmospheric transmittance value for the atmospheric correction subsystem.

[0077] As can be seen from equation (11), in order to increase the measurement work and equipment, atmospheric path radiation correction is realized, and the original removal of atmospheric path radiation in front of the target is changed to compensation for atmospheric path radiation behind the target, which is more beneficial to improving the accuracy of infrared radiation inversion for high elevation angle long distance targets. The equation does not include the intercept of pixel response, and only the K value of the linear response model is used for the parameters of the equipment itself. Therefore, when calibrating the equipment, only the response proportional coefficient K of the equipment needs to be calibrated, and the intercept does not need to be calibrated. This solves the previous problem of intercept calibration and reduces the calibration cost.

[0078] The atmospheric correction subsystem mainly consists of measuring equipment such as a solar radiometer (i.e., an atmospheric water vapor analyzer), an automatic weather station (a real-time measurement system for ground meteorological parameters), a visibility meter (a ground aerosol particle measurement system), and a micropulse lidar, as well as atmospheric transmission correction software. It can provide atmospheric spectral transmittance and the wavelength response function of the instrument to calculate the atmospheric transmittance and turbulence effects in the corresponding band, and can also provide atmospheric path radiation.

[0079] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0080] Example

[0081] like Figure 1 As shown, an embodiment of the present invention proposes a method for infrared radiation inversion of an airborne target using an infrared radiation measuring instrument.

[0082] The target radiation inversion process described in this method is as follows: The target's radiation is obtained by subtracting the "background" gray level from the measured response gray level, including both the sky radiation response and the zero-input response; then, proportional dimension recovery is performed; followed by atmospheric back-range radiation correction and compensation; and finally, atmospheric transmittance correction. The process includes the following steps:

[0083] The response grayscale and background grayscale of aerial targets were measured using an infrared radiation meter.

[0084] The atmospheric correction subsystem collects, calculates, and corrects the downstream atmospheric radiation.

[0085] Atmospheric transmittance is collected and calculated by the atmospheric correction subsystem;

[0086] Based on the linear response model, the target response grayscale is processed by subtracting the background grayscale and then compensated for the subsequent atmospheric radiation to calculate the target radiation, thereby completing the target radiation inversion.

[0087] The following is a detailed analysis of the target radiation inversion:

[0088] (1) Calibration of the slope of the infrared radiation response of the equipment

[0089] When calibrating the equipment, only the proportional coefficient K of the equipment's response needs to be calibrated; the intercept does not need to be calibrated.

[0090] (2) Measurement of atmospheric correction subsystem parameters

[0091] The instruments in the atmospheric correction subsystem continuously collect atmospheric parameters.

[0092] (3) The background radiation of this pixel is calculated, and background subtraction is performed.

[0093] The “background” grayscale of this pixel is obtained by radiation conversion to the grayscale of other pixels that only contain the sky background and are not affected by the target radiation input. The grayscale of this pixel is then reduced by the “background” grayscale.

[0094] (4) Dimensional restoration

[0095] Dividing the pixel grayscale by the response slope restores the infrared radiation dimension, thus obtaining the target radiation at the device.

[0096] (5) Correction and compensation for radiation calculation in the later stages

[0097] The atmospheric correction subsystem calculates the atmospheric radiation (back path radiation) along the extended path of the line connecting the equipment and the target based on atmospheric parameters and atmospheric models. It then corrects the radiation by using measured sky response grayscale and calculated sky values, and performs summation compensation on the target radiation at the equipment location.

[0098] (6) Atmospheric transmittance correction

[0099] The atmospheric correction subsystem calculates the atmospheric transmittance along the path from the target to the equipment based on atmospheric parameters and atmospheric models, and extrapolates the infrared radiation from the target at the equipment to the target, thus completing the inversion of the target's radiation.

[0100] This inversion method replaces the original method of removing atmospheric path radiation in front of the target with compensating for atmospheric path radiation behind the target, resulting in higher accuracy for distant targets at high elevation angles. Atmospheric path radiation is calculated by the atmospheric correction subsystem, which has limited accuracy. Correcting this subsystem, especially for weak targets, is particularly beneficial for improving the accuracy of infrared radiation inversion.

[0101] This inversion method for infrared target radiation measurement does not include the pixel response intercept. It only uses the K value of the linear response model for the equipment's own parameters. Therefore, when calibrating the equipment, only the response scaling factor K needs to be calibrated, eliminating the need for intercept calibration. This solves the previous problem of intercept calibration and reduces calibration costs. The sky radiation response is obtained along with the target tracking measurement and used to correct atmospheric path radiation, eliminating the need for separate atmospheric path radiation correction measurements.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for inverting infrared radiation of an aerial target using an infrared radiation measuring instrument, the method comprising: The response grayscale of aerial targets was measured using an infrared radiation meter. and background grayscale ; The atmospheric correction subsystem collects, calculates, and corrects post-process atmospheric radiation; specifically, it includes: Step 3-1) Use an infrared radiation measurement device to collect the sky radiation response grayscale of a certain pixel of the camera at two pointing angles. and ; Step 3-2) Calculate the sky radiation corresponding to the two pointing angles using the atmospheric correction subsystem. and ; Step 3-3) Obtain the atmospheric path radiation ratio correction factor according to the following formula. for: in, K The coefficients of the pre-calibrated linear response model; This leads to the slope of the device's sky response change. for: Calculated values ​​obtained by combining atmospheric correction subsystem The latter atmospheric radiation can be obtained from the following formula. : ； Atmospheric transmittance is collected and calculated by the atmospheric correction subsystem; Based on the coefficients of the pre-calibrated linear response model K The calculated atmospheric transmittance value of the atmospheric correction subsystem. Combined with the response grayscale of aerial targets and background grayscale and subsequent atmospheric radiation The target radiation can be obtained from the following formula. Thus, the target radiation inversion is completed: 。 2. The infrared radiation inversion method for measuring aerial targets using an infrared radiation measuring instrument according to claim 1, characterized in that, Step 3-1) includes: The sky radiative response grayscale of a certain pixel of the camera is repeatedly collected using an infrared radiation measurement device at the first pointing angle. After smoothing and calculating the collected data from multiple frames, the first sky radiative response grayscale corresponding to the first pointing angle is obtained. ; The sky radiative response grayscale of a certain pixel of the camera is repeatedly collected using an infrared radiation measurement device at the second pointing angle. After smoothing and calculating the collected data from multiple frames, the second sky radiative response grayscale corresponding to the second pointing angle is obtained. .

3. The infrared radiation inversion method for measuring aerial targets using an infrared radiation measuring instrument according to claim 2, characterized in that, Step 3-2) includes: Based on the atmospheric parameters collected by the atmospheric correction subsystem at the corresponding first pointing angle, the atmospheric path radiation between the target and the infrared radiation measurement device at the corresponding first pointing angle is calculated. and subsequent radiation Based on this, the first sky radiation was calculated. ; Based on the atmospheric parameters collected by the atmospheric correction subsystem at the corresponding second pointing angle, the atmospheric path radiation between the target and the infrared radiation measurement device at the corresponding second pointing angle is calculated. and subsequent radiation The second sky radiation was calculated. .

4. The infrared radiation inversion method for measuring aerial targets using an infrared radiation measuring instrument according to claim 3, characterized in that, First Sky Radiation Satisfy the following formula: Second sky radiation Satisfy the following formula: 。

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