Infrared emissivity out-field measurement method

Abstract

The application discloses an infrared emissivity outfield measurement method, which adopts four target cloths with different emissivity as calibration bodies, calibrates the emissivity of the target cloths by using a high-precision surface source black body and a gold plate, and then corrects the atmosphere and environmental radiation by using the four target cloths. Meanwhile, the influences of the uplink atmospheric radiation, the downlink atmospheric radiation, the environmental radiation and the atmospheric attenuation are corrected, and then the target and typical surface emissivity inversion is completed. The application can not only obtain accurate target and typical surface emissivity, meet the engineering application needs, but also significantly reduce the test cost, and does not need complex and expensive test special equipment and does not need to develop a special outfield test system. Only the calibration bodies such as the surface source black body and the gold plate and the outfield hanging test equipment are needed, so that the outfield infrared emissivity measurement can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of infrared emissivity measurement, in particular to an infrared emissivity field measurement method. BACKGROUND

[0002] Infrared emissivity is a kind of inherent property of an object, which is closely related to the infrared radiation characteristics of a target. Accurate acquisition of the emissivity of a target surface is of great significance for obtaining the infrared radiation characteristics of the target and realizing target detection and tracking. Experimental measurement is the most direct and effective method for obtaining the infrared emissivity of an object. Infrared emissivity measurement is mainly divided into laboratory measurement and field measurement. Laboratory measurement mainly relies on special optical equipment, and has high measurement accuracy, but is expensive and requires the preparation of samples that meet the testing requirements according to the performance of the instrument, which is a complex process. Field measurement is affected by atmospheric radiation, environmental radiation, and atmospheric attenuation, and needs to be corrected for atmospheric radiation and environmental radiation to obtain accurate object surface emissivity to meet engineering needs.

[0003] Currently, the measurement of emissivity mainly relies on laboratory measurement, which requires expensive testing equipment. The field measurement system is complex and the operation procedure is tedious, resulting in high testing cost.

[0004] The statements herein only provide background technology related to the present application, and do not necessarily constitute the prior art. SUMMARY

[0005] The present application aims to provide an infrared emissivity field measurement method, which can not only obtain accurate target and typical surface emissivity, but also does not require complex and expensive testing equipment or the development of a special field testing system, significantly reducing the testing cost.

[0006] In order to achieve the above-mentioned purpose, the present application provides an infrared emissivity field measurement method, comprising the following steps:

[0007] Step S1, obtaining the radiation brightness of a high-precision surface element blackbody, a gold plate and a large-area calibration body by low-altitude hanging flight, and synchronously collecting the surface temperature of the large-area standard body;

[0008] Step S2, calculating the surface emissivity of the large-area standard body;

[0009] Step S3, obtaining the in-pupil radiation brightness of the target and the ground object background by high-altitude hanging flight, and synchronously collecting the surface temperature of the target, the large-area standard body and the typical ground object;

[0010] Step S4, calculating the atmospheric radiation, environmental radiation and atmospheric attenuation;

[0011] Step S5, inverting the surface emissivity of the target and the typical ground object.

[0012] In the step S1, four target cloths with emissivity of 0.9, 0.6, 0.3 and 0.1 are selected, each of which has a size of 5m*5m, and the four target cloths are regularly arranged, and the high-precision surface element black body and the gold plate are arranged beside the large-area standard body, so that the target cloths and the high-precision surface element black body and the gold plate are located in the field of view of the detector when flying at low altitude.

[0013] In the step S1, the surface temperatures of the target and the typical ground surface, the large-area target cloth surface and the gold plate surface are measured by a contact type temperature measuring instrument.

[0014] In the step S2, the surface temperature T bb of the black body is read from the control panel of the black body, and the surface temperature T gb of the gold plate is measured by a contact type temperature measuring instrument, which are used to calculate the body radiation brightness of the black body and the gold plate.

[0015] According to the Planck law, the body radiation brightness calculation formula of the black body and the gold plate is as follows:

[0016]

[0017]

[0018] In the formula, L bb is the body radiation brightness of the black body; L gb is the body radiation brightness of the gold plate; ε bb is the emissivity of the black body; ε gb is the emissivity of the gold plate; T bb is the surface temperature of the black body; T gb is the surface temperature of the gold plate; C1 is the first Planck constant, 3.743*10 8 m 4 ·W / m 2 ; C2 is the second Planck constant, 1.439*10 4 m·K; λ is the infrared radiation wavelength of the infrared detection device, in meters; e is the natural constant 2.718; π is the natural constant 3.141;

[0019] The entrance pupil radiation brightness calculation formula of the black body and the gold plate when flying at low altitude is as follows:

[0020] L′ bb =L bb +ρ bb L atm↓ +L atm↑ (3)

[0021] L′ gb =L gb +ρ gb L atm↓ +L atm↑(4)

[0022] L′ bb is the luminance of the entrance pupil of the blackbody; L′ gb is the luminance of the entrance pupil of the gold plate; ρ bb is the reflectivity of the blackbody, ρ bb = 1 - ε bb ; ρ gb is the reflectivity of the gold plate, ρ gb = 1 - ε gb ; L atm↓ is the downward radiation in the atmospheric environment at the first test height; L atm↑ is the upward radiation in the atmospheric environment at the low-altitude hang flight;

[0023] According to the formulas (3) and (4), the calculation formulas of the downward radiation L atm↓ and the upward radiation L atm↑ in the atmospheric environment at the low-altitude hang flight are as follows:

[0024]

[0025]

[0026] The body radiation luminance L bb and L gb of the blackbody and the gold plate, and the entrance pupil radiation luminance L b ′ b and L g ′ b of the blackbody and the gold plate are substituted into the formulas (3) and (4), so as to obtain the downward radiation L atm↓ and the upward radiation L atm↑ in the atmospheric environment at the low-altitude hang flight.

[0027] The four large-area target cloths are respectively marked as 1, 2, 3 and 4, and the body radiation luminance calculation formula is as follows:

[0028]

[0029] In the formula, L lbb (i) is the body radiation luminance of the i-th target cloth; ε lbb (i) is the emissivity of the i-th target cloth; T lbb (i) is the surface temperature of the i-th target cloth, L bb (T lbb (i)) is the blackbody radiation luminance at the T lbb (i) temperature;

[0030] L l ′ bb (i) = L lbb (i) + ρ lbb(i) L atm↓ + L atm↑ = ε lbb (i) L bb (T lbb (i)) + (1 - ε lbb (i)) L atm↓ + L atm↑ (8)

[0031] wherein, L l ′ bb (i) is the entrance pupil radiance of the i-th target cloth when flying at low altitude; ρ lbb (i) is the reflectivity of the i-th target cloth;

[0032] According to formula (8), the emissivity calculation formula of the large-area target cloth is:

[0033]

[0034] The reflectivity of the large-area target cloth is:

[0035] ρ lbb (i) = 1 - ε lbb (i) (10).

[0036] In the step S3, when flying at high altitude, the flight height is 500 m, the target and ground object background radiance is obtained by push-broom imaging, and the target and typical ground object surface temperature is synchronously collected.

[0037] In the step S4, when flying at high altitude, the entrance pupil radiance of the large-area target cloth is:

[0038] L″ lbb (i) = [L lbb (i) + ρ lbb (i) (L″ atm↓ + L bg )] · τ + L″ atm↑ (11)

[0039] wherein, L″ lbb (i) is the entrance pupil radiance of the i-th target cloth when flying at high altitude; L lbb (i) is the body radiance of the i-th target cloth; L″ atm↓ is the downward radiation of the atmospheric environment when flying at high altitude; L″ atm↑ is the upward radiation of the atmospheric environment when flying at high altitude; τ is the atmospheric attenuation from the ground to the detector when flying at high altitude;

[0040] As can be seen from equation (11), there are four factors affecting the target and background radiation: atmospheric up-going radiation, atmospheric down-going radiation, atmospheric attenuation, and environmental radiation. The emissivity of the four large-area target cloths has been obtained from low-altitude flight. The body radiation brightness of the four target cloths can be known by using the surface temperature of the target cloths during high-altitude flight. By solving the equations simultaneously, atmospheric up-going radiation, atmospheric down-going radiation, atmospheric attenuation, and environmental radiation can be obtained.

[0041] In step S5, during high-altitude flight, the radiance of the large-area target cloth, the target itself, and typical ground features is collected by the detector. The formula for calculating the entrance pupil radiance of the ground target and the background of the site is as follows:

[0042] L″ target =[L target +ρ target (L″ atm↓ +L bg )]·τ+L″ atm↑ (12)

[0043] In the formula, L″ target L is the entrance pupil radiance of ground targets and background features when flying at high altitude; target The radiance of the ground target and the background of the position; ρ target Reflectance of ground targets and the background of the position;

[0044] The emissivity of the target and typical ground features is:

[0045]

[0046] The outdoor infrared emissivity measurement method provided by this invention can not only obtain accurate emissivity of targets and typical ground features to meet the needs of engineering applications, but also significantly reduce testing costs. It does not require complex and expensive special testing equipment, nor does it require the development of a special outdoor testing system. Only a blackbody, a gold plate, or other calibration body and an outdoor flight test device are needed to realize outdoor infrared emissivity measurement. Attached Figure Description

[0047] Figure 1 This is a flowchart of an infrared emissivity field measurement method provided by the present invention. Detailed Implementation

[0048] The following is based on Figure 1 The preferred embodiments of the present invention will be described in detail below.

[0049] like Figure 1As shown, this invention provides an infrared emissivity field measurement method. To simultaneously correct for the effects of upward atmospheric radiation, downward atmospheric radiation, environmental radiation, and atmospheric attenuation, four target fabrics with different emissivities are used as calibration bodies. First, the emissivity of the target fabrics is calibrated using a high-precision surface source blackbody and a gold plate. Then, the four target fabrics are used to correct for atmospheric and environmental radiation, thereby completing the emissivity inversion of the target and typical ground features. Specifically, it includes the following steps:

[0050] Step S1: Obtain the radiation brightness of high-precision blackbody, gold plate and large-area calibration body by low-altitude flight, and simultaneously collect the surface temperature of large-area standard body.

[0051] The number of large-area standard bodies is the same as the number of influencing factors for correction. This patent corrects four factors: atmospheric down-current radiation, atmospheric up-current radiation, environmental radiation, and atmospheric attenuation. Four target cloths with different emissivity are selected for the large-area standard bodies. The four target cloths are arranged in a regular pattern, with emissivity of 0.9, 0.6, 0.3, and 0.1 respectively. Each target cloth is 5m×5m in size. High-precision blackbody and gold plate are arranged next to the large-area standard bodies to ensure that the target cloth, high-precision blackbody and gold plate are located in the detector's field of view when flying at low altitude. They are used to correct the four factors: atmospheric down-current radiation, atmospheric up-current radiation, environmental radiation, and atmospheric attenuation. The surface temperature is measured by a contact thermometer on the surface of the target and typical ground features, the surface of the large-area target cloth, and the surface of the gold plate.

[0052] Step S2: Calculate the emissivity of a large-area standard surface;

[0053] The surface temperature T of the blackbody is read from the blackbody's control panel. bb The surface temperature T of the gold plate was measured using a contact thermometer. gb , used to calculate the bulk radiance of the blackbody and the gold plate;

[0054] According to Planck's law, the formula for calculating the bulk radiance of the blackbody and the gold plate is as follows:

[0055]

[0056]

[0057] In the formula, L bb L is the bulk radiance of the blackbody; gb The radiance of the gold plate; ε bb ε is the emissivity of the blackbody; gb T represents the emissivity of the gold plate. bb T is the surface temperature of the blackbody. gb C is the surface temperature of the gold plate; C1 is Planck's first constant, 3.743 × 10⁻⁶. 8 m 4 ·W / m2 ; C2 is the second Planck constant, 1.439 x 10 4 m K; λ is the infrared radiation wavelength of the infrared detection device, in m; e is the natural constant 2.718; π is the natural constant 3.141;

[0058] The formula for calculating the entrance pupil radiation luminance of the black body and the gold plate when flying at low altitude is:

[0059] L' bb = L bb + p bb L atm↓ + L atm↑ (3)

[0060] L' gb = L gb + p gb L atm↓ + L atm↑ (4)

[0061] In the formula, L' bb is the entrance pupil radiation luminance of the black body; L' gb is the entrance pupil radiation luminance of the gold plate; p bb is the reflectivity of the black body, p bb = 1 - e bb ; p gb is the reflectivity of the gold plate, p gb = 1 - e gb ; L atm↓ is the downward radiation in the atmospheric environment at the first test height; L atm↑ is the upward radiation in the atmospheric environment when flying at low altitude;

[0062] According to the formulas (3) and (4), the calculation formulas of the downward radiation L atm↓ in the atmospheric environment and the upward radiation L atm↑ in the atmospheric environment when flying at low altitude are:

[0063]

[0064]

[0065] Substituting the body radiation luminance L bb and L gb of the black body and the gold plate, and the entrance pupil radiation luminance L' bb and L' gb of the black body and the gold plate into the formulas (3) and (4), the downward radiation L atm↓ in the atmospheric environment and the upward radiation L atm↑ in the atmospheric environment when flying at low altitude are obtained;

[0066] Four large-area target cloths are marked as 1, 2, 3 and 4 respectively, and the body radiation brightness calculation formula of the four large-area target cloths is:

[0067]

[0068] In the formula, L lbb (i) is the body radiation brightness of the i-th target cloth; ε lbb (i) is the emissivity of the i-th target cloth; T lbb (i) is the surface temperature of the i-th target cloth, L bb (T lbb (i)) is the blackbody radiation brightness at T lbb (i) temperature;

[0069] L′ lbb (i) = L lbb (i) + ρ lbb (i) L atm↓ + L atm↑ = ε lbb (i) L bb (T lbb (i)) + (1-ε lbb (i)) L atm↓ + L atm↑ (8)

[0070] In the formula, L′ lbb (i) is the entrance pupil radiation brightness of the i-th target cloth when flying at low altitude; ρ lbb (i) is the reflectivity of the i-th target cloth;

[0071] According to formula (8), the emissivity calculation formula of the large-area target cloth is obtained as follows:

[0072]

[0073] The reflectivity of the large-area target cloth is:

[0074] ρ lbb (i) = 1-ε lbb (i) (10)

[0075] Step S3, obtaining the entrance pupil radiation brightness of the target and the ground object background by flying at high altitude, and synchronously collecting the surface temperature of the target, the large-area standard body and the typical ground object.

[0076] When flying at high altitude, the flight height is about 500m, the target and the ground object background radiation brightness are obtained by push-broom imaging, and the surface temperature of the target and the typical ground object is synchronously collected.

[0077] Step S4, calculating the atmospheric radiation, the environmental radiation and the atmospheric attenuation;

[0078] The in-pupil radiance of the large-area target cloth during high-altitude flight is:

[0079] L" lbb (i) = [L lbb (i) + p lbb (L" atm↓ + L bg )]·τ + L" atm↑ (11)

[0080] In the formula, L" lbb (i) is the in-pupil radiance of the i-th target cloth during high-altitude flight; L lbb (i) is the body radiance of the i-th target cloth; L" atm↓ is the atmospheric downwelling radiation during high-altitude flight; L" atm↑ is the atmospheric upwelling radiation during high-altitude flight; and τ is the atmospheric attenuation from the ground to the detector during high-altitude flight.

[0081] As can be seen from the formula (11), there are four factors affecting the target and background radiation, namely, the atmospheric upwelling radiation, the atmospheric downwelling radiation, the atmospheric attenuation, and the environmental radiation. The emissivity of the four large-area target cloths has been obtained by low-altitude flight, and the body radiance of the four target cloths can be obtained by using the surface temperature of the target cloth during high-altitude flight. The atmospheric upwelling radiation, the atmospheric downwelling radiation, the atmospheric attenuation, and the environmental radiation can be obtained by solving the equations.

[0082] Step S5, inverting the emissivity of the target and the typical ground surface;

[0083] During high-altitude flight, the radiance of the large-area target cloth, the target, and the typical ground surface is collected by the detector, and the in-pupil radiance calculation formula of the ground target and the background of the position is:

[0084] L" target = [L target + p target (L" atm↓ + L bg )]·τ + L" atm↑ (12)

[0085] In the formula, L" target is the in-pupil radiance of the ground target and the background of the position during high-altitude flight; L target is the body radiance of the ground target and the background of the position; p target is the reflectivity of the ground target and the background of the position.

[0086] The emissivity of the surface of the target and the typical ground surface is:

[0087]

[0088] The method for measuring the infrared emissivity in an external field provided by the application realizes the emissivity calibration of a large-area target cloth when flying at a height of 20 m, and realizes the atmospheric radiation and environmental radiation correction when flying at a height of 500 m, and the emissivity of a target and a typical ground surface is inverted.

[0089] The embodiment of the application adopts an unmanned aerial vehicle to carry infrared detection equipment for emitting medium waves and long waves, a high-precision surface source black body and a standard gold plate are arranged near a ground target as high-precision calibration bodies, and a large-area black calibration target cloth is used as a calibration body. The low-altitude flight height is set to 20 m, the unmanned aerial vehicle flies according to a predetermined flight route, flies from the ground to a height of 20 m, and calibrates the large-area calibration target cloth by using the high-precision calibration body. At the height of 20 m, the high-precision surface source black body, the standard gold plate and the four large-area calibration target cloths are located in the field of view of the infrared detection equipment and just fill the entire field of view, the entrance pupil radiation brightness and the body radiation brightness of the high-precision black body and the standard gold plate are obtained, the atmospheric environmental radiation and the body radiation and reflectivity of the large-area calibration target cloth are obtained by inversion according to the entrance pupil radiation brightness and the body radiation brightness of the high-precision black body and the standard gold plate. The specific process is as follows:

[0090] The surface temperature T of the black body is read from the control panel of the black body bb The surface temperature T of the gold plate is measured by using a contact type temperature measuring instrument gb , which is used to calculate the body radiation brightness of the black body and the gold plate;

[0091] According to the Planck law, the body radiation brightness calculation formula of the black body and the gold plate is:

[0092]

[0093]

[0094] In the formula, L bb is the body radiation brightness of the black body; L gb is the body radiation brightness of the gold plate; ε bb is the emissivity of the black body; ε gb is the emissivity of the gold plate; T bb is the surface temperature of the black body; T gb is the surface temperature of the gold plate; C1 is the first Planck constant, 3.743*10 8 m 4 ·W / m 2 ; C2 is the second Planck constant, 1.439*10 4 m·K; λ is the infrared radiation wavelength of the infrared detection equipment, in meters; e is the natural constant 2.718; π is the natural constant 3.141;

[0095] The entrance pupil radiation brightness calculation formula of the black body and the gold plate when flying at a low altitude is:

[0096] L' bb = L bb + ρ bb L atm↓ + L atm↑ (3)

[0097] L' gb = L gb + ρ gb L atm↓ + L atm↑ (4)

[0098] In the formula, L' bb is the entrance pupil radiance of the black body; L' gb is the entrance pupil radiance of the gold plate; ρ bb is the reflectivity of the black body, ρ bb = 1-ε bb ; ρ gb is the reflectivity of the gold plate, ρ gb = 1-ε gb ; L atm↓ is the downward radiation in the atmospheric environment at the first test height; and L atm↑ is the upward radiation in the atmospheric environment when flying at low altitude.

[0099] According to the formulas (3) and (4), the calculation formulas of the downward radiation L atm↓ in the atmospheric environment when flying at low altitude and the upward radiation L atm↑ in the atmospheric environment are as follows:

[0100]

[0101]

[0102] Substituting the body radiance L bb and L gb of the black body and the gold plate and the entrance pupil radiance L' bb and L' gb of the black body and the gold plate into the formulas (3) and (4), the downward radiation L atm↓ in the atmospheric environment when flying at low altitude and the upward radiation L atm↑ in the atmospheric environment are obtained.

[0103] The four large-area target cloths are respectively marked as 1, 2, 3 and 4, and the calculation formula of the body radiance of the four large-area target cloths is as follows:

[0104]

[0105] In the formula, L lbb (i) is the body radiance of the i-th target cloth; and ε lbb(i) is the emissivity of the i-th target cloth; T lbb (i) is the surface temperature of the i-th target cloth, L bb lbb (i) is the surface temperature of the i-th target cloth, L lbb (i) is the blackbody radiation luminance at the temperature T

[0106] L′ lbb (i) is the entrance pupil radiation luminance of the i-th target cloth when flying at low altitude; ρ lbb (i) is the reflectivity of the i-th target cloth; lbb (i) is the reflectivity of the i-th target cloth; atm↓ +L atm↑ = ε lbb (i) L bb (T lbb (i)) + (1- ε lbb (i)) L atm↓ +L atm↑ (8)

[0107] In the formula, L′ lbb (i) is the entrance pupil radiation luminance of the i-th target cloth when flying at low altitude; ρ lbb (i) is the reflectivity of the i-th target cloth;

[0108] According to formula (8), the emissivity calculation formula of the large-area target cloth is:

[0109]

[0110] The reflectivity of the large-area target cloth is:

[0111] ρ lbb (i) = 1- ε lbb (i) (10)

[0112] When flying at high altitude, the flight height is about 500 m, the target and ground object background radiation luminance are obtained by push-broom imaging, and the target and typical ground object surface temperature are synchronously collected, and the entrance pupil radiation luminance of the large-area target cloth is:

[0113] L″ lbb (i) = [L lbb (i) + ρ lbb (i) (L″ atm↓ + L bg )]· τ + L″ atm↑ (11)

[0114] In the formula, L″ lbb (i) is the entrance pupil radiation luminance of the i-th target cloth when flying at high altitude; L lbb (i) is the body radiation luminance of the i-th target cloth; L″ atm↓ is the downward radiation in the atmospheric environment when flying at high altitude; L″ atm↑ ​The upward radiation of the atmospheric environment during high-altitude flight; τ is the atmospheric attenuation from the ground to the detector during high-altitude flight;

[0115] As can be seen from Equation (11), there are four factors affecting the target and background radiation: atmospheric up-going radiation, atmospheric down-going radiation, atmospheric attenuation, and environmental radiation. The emissivity of the four large-area target cloths can be obtained by low-altitude flight. The body radiation brightness of the four target cloths can be known by the surface temperature of the target cloths during high-altitude flight. By solving the equations simultaneously, atmospheric up-going radiation, atmospheric down-going radiation, atmospheric attenuation, and environmental radiation can be obtained.

[0116] The radiance of large-area target deployments, targets, and typical ground features was collected by the detector. The formula for calculating the entrance pupil radiance of ground targets and the background of the site is as follows:

[0117] L″ target =[L target +ρ target (L″ atm↓ +L bg )]·τ+L″ atm↑ (12)

[0118] In the formula, L″ target L is the entrance pupil radiance of ground targets and background features when flying at high altitude; target The radiance of the ground target and the background of the position; ρ target Reflectance of ground targets and the background of the position;

[0119] The emissivity of the target and typical ground features is:

[0120]

[0121] This invention avoids the use of complex and expensive large-area blackbody and laboratory emissivity measurement equipment, saving costs. Under field conditions, it can achieve target and ground background infrared emissivity measurement that meets engineering needs at a lower cost, and can conveniently obtain the emissivity of target and typical ground surface.

[0122] It should be noted that in the embodiments of the present application, the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0123] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

[0124] Although the content of the present application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as limiting the present application. After reading the above content, various modifications and alternatives of the present application will be obvious to those skilled in the art. Therefore, the protection scope of the present application should be defined by the appended claims.

Claims

1. An infrared emissivity ex situ measurement method, characterized by, Comprise the following steps: Step S1, low altitude hanging fly to obtain high precision unit blackbody, gold plate and large area standard body radiation brightness, and synchronous acquisition of large area standard body surface temperature; Large area standard body selects four different emissivity target cloth, four target cloth regular arrangement, emissivity is 0.9, 0.6, 0.3, 0.1, each target cloth size is 5m×5m, high precision unit blackbody and gold plate are arranged beside the large area standard body, ensure that the target cloth and high precision unit blackbody, gold plate are located in the field of view of the detector when low altitude hanging fly, for correcting atmospheric downwelling radiation, atmospheric upwelling radiation, environmental radiation, atmospheric attenuation four factors; Step S2, calculate the surface emissivity of large area standard body; Step S3, high altitude hanging fly to obtain target and ground object background into the pupil radiation brightness, and synchronous acquisition of target, large area standard body and typical ground object surface temperature; Step S4, calculate atmospheric radiation, environmental radiation and atmospheric attenuation; The influencing factors of target and background radiation are four, respectively atmospheric upwelling radiation, atmospheric downwelling radiation, atmospheric attenuation, environmental radiation, the emissivity of four large area target cloth has been obtained by low altitude hanging fly, the body radiation brightness of four target cloth can be obtained by using the surface temperature of target cloth in high altitude hanging fly, simultaneous solution can obtain atmospheric upwelling radiation, atmospheric downwelling radiation, atmospheric attenuation, environmental radiation; Step S5, inversion target and typical ground object surface emissivity.

2. The infrared emissivity ex situ measurement method of claim 1, wherein, In the step S2, the surface temperature T of the black body is read from the control panel of the black body bb The surface temperature T of the gold plate is measured by using a contact type temperature measuring instrument gb for calculating the body radiation brightness of the black body and the gold plate; According to Planck's law, the body radiation brightness calculation formula of the blackbody and gold plate is: wherein L bb is the blackbody radiance of the body; L gb is the blackbody radiance of the gold plate; ε bb is the emissivity of the blackbody; ε gb is the emissivity of the gold plate; T bb is the surface temperature of the blackbody; T gb is the surface temperature of the gold plate; C1 is the first Planck constant, 3.743 x 10 8 m 4 ·W / m 2 ; C2 is the second Planck constant, 1.439 x 10 4 m·K; λ is the infrared radiation wavelength of the infrared detection device, in units of m; e is the natural constant 2.718; π is the natural constant 3.141; The formula for calculating the radiation brightness of the blackbody and gold plate into the pupil at low altitude is: L' bb = L bb + p bb L atm↓ + L atm↑ (3) L' gb = L gb + p gb L atm↓ + L atm↑ (4) where L' = L - L bb ; L = L - L gb ; ρ = ρ - ρ bb ; and ρ = ρ - ρ bb . bb ; ρ = ρ - ρ gb . gb ; ρ = ρ - ρ gb . atm↓ ; L = L - L atm↑ . The calculation formulae of the downward radiation L atm↓ and the upward radiation L atm↑ in the atmosphere environment when flying at low altitude are obtained according to formulae (3), (4). The body radiation luminance L of the black body and the gold plate bb and L gb The entrance pupil radiation luminance L' of the black body and the gold plate bb and L' gb Substitute formula (3) and (4) to obtain the downward radiation L of the atmospheric environment when flying at low altitude atm↓ and the upward radiation L of the atmospheric environment atm↑ ; Four large area target cloth is marked as 1, 2, 3, 4, the body radiation brightness calculation formula is: where L lbb (i) is the bulk radiance of the i-th target cloth; ε lbb (i) is the emissivity of the i-th target cloth; T lbb (i) is the surface temperature of the i-th target cloth, L bb (T lbb (i)) is the blackbody radiance at T lbb (i) temperature; L' lbb (i) = L lbb (i) + p lbb (i) L atm↓ + L atm↑ = ε lbb (i) L bb (T lbb (i)) + (1 - ε lbb (i)) L atm↓ + L atm↑ (8) where L' = L - L0 lbb (i) is the entrance pupil radiance of the i-th target cloth when flying at low altitude; p lbb (i) is the reflectivity of the i-th target cloth According to formula (8), the emissivity calculation formula of large area target cloth is: The reflectivity of large area target cloth is: p lbb (i) = 1 - ε lbb (i) (10).

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