CN210513419U - Radiometer for remote sensor on-orbit atmospheric correction - Google Patents
Radiometer for remote sensor on-orbit atmospheric correction Download PDFInfo
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- CN210513419U CN210513419U CN201921179262.3U CN201921179262U CN210513419U CN 210513419 U CN210513419 U CN 210513419U CN 201921179262 U CN201921179262 U CN 201921179262U CN 210513419 U CN210513419 U CN 210513419U
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Abstract
The utility model discloses a radiometer for remote sensor on-orbit atmospheric correction, which comprises an integrating sphere, wherein the inner surface of the integrating sphere is coated with a diffuse reflection coating; the integrating sphere is provided with a ground light gathering port, a sunlight incident port and at least one detector interface; the ground light gathering port is connected with the light gathering system, and a first electromagnetic valve is arranged between the ground light gathering port and the light gathering system; the sunlight incident port is provided with a second electromagnetic valve; the detector interface is provided with a collimation correction module and a detector module; the incident light of the ground light gathering port and the sunlight incident port enters the integrating sphere and is reflected for multiple times by the diffuse reflection coating, a uniform illumination surface is formed on the inner surface of the integrating sphere, and the uniform illumination surface is led into the detector module through the collimation correction module of the detector interface. The calibration device takes the stable known sun as a reference, eliminates the influence of self attenuation and change on the calibration precision in principle, can accurately measure the atmospheric characteristic parameters above the calibration field, and has the advantages of simple structure, good stability and reliable and effective acquired signals.
Description
Technical Field
The invention relates to the technical field of spectral radiometric calibration, in particular to a radiometer for on-orbit atmospheric correction of a remote sensor.
Background
With the development of national economy and science and technology, the support of space remote sensing data is urgently needed in the fields of national macro decision, national defense and military, national and local resource investigation, precision agriculture, environmental monitoring, atmospheric exploration, extreme disaster forecast and the like. The hyperspectral imaging technology is a remote sensing technology developed in the 80 s, and is different from a traditional spectrometer in that the hyperspectral imaging technology integrates an image and a spectrum (the map is integrated), and continuous fine spectral information of a target is synchronously acquired while two-dimensional spatial image information of the target is acquired with nanoscale hyperspectral resolution, so that the detection capability of space remote sensing is greatly improved, and the hyperspectral imaging technology can be widely applied to observation of land, atmosphere, ocean and the like.
The reflectivity curve of the ground object can be inverted through ground three-dimensional cube data acquired by the hyperspectral camera on track; however, under the influence of the characteristics of the atmosphere over the ground object, the inverted reflectivity curve has a certain difference from the real reflectivity curve of the ground object target, and due to the scattering and absorption contributions of molecules and aerosol particles in the atmosphere, the radiation value of the target before the detector passes through the ascending atmosphere and the real radiation value of the ground object target have a large difference, and the difference is greatly changed along with the difference of weather conditions and local atmosphere parameters (such as water vapor and other absorbed gas content, atmospheric aerosol, temperature, humidity, air pressure and the like). Therefore, to acquire high-quality hyperspectral space remote sensing data which can be traced to SI (international basic unit system), accurately and quantitatively interpreting ground object information, a research on ground observation work by a hyperspectral imager must be deeply conducted, atmospheric correction is conducted, and atmospheric influence is deducted.
The existing atmospheric radiation correction method mainly comprises the steps of measuring actual atmospheric transmittance and simulating and calculating the atmospheric transmittance according to detected atmospheric parameters. However, it is very difficult to measure the atmospheric transmittance of a long inclined path in real time, and it is not easy to implement. The method mainly adopts a computer software simulation analysis method for correcting the measured radiation signal by constructing a calculation mode of the atmospheric spectral transmittance, generally utilizes foreign atmospheric radiation transmission software (such as MODTRAN and the like) to calculate the atmospheric transmittance by adopting a standard atmospheric mode, and has the advantages of simple operation, low cost, short period and the like. However, the actual atmosphere of a typical region in China has a great difference from the standard atmosphere mode, and the calculation accuracy and the calculation efficiency of the actual atmosphere have certain limitations. Therefore, in practical engineering application, the atmospheric measurement instrument still needs to be adopted to carry out actual observation and correction on the atmospheric characteristic parameters at the calibration time of the measurement site. However, in the current practical engineering application, a plurality of atmospheric measuring instruments are needed for correcting atmospheric characteristic parameters, the measuring process is complex, a self-calibration device and an instrument attenuation self-correction function are lacked, and the long-term stability is difficult to maintain.
Disclosure of Invention
The invention provides a radiometer for remote sensor on-orbit atmospheric correction, which takes stable and known sun as reference, eliminates the influence of self attenuation and change on calibration precision of a calibration source in principle, can accurately measure atmospheric characteristic parameters above a calibration field, eliminates atmospheric profile errors and inverts atmospheric parameters.
Therefore, the invention adopts the following technical scheme:
the first embodiment is as follows:
a radiometer for remote sensor on-orbit atmospheric calibration, as shown in FIG. 1, comprises an integrating sphere 1, the inner surface of the integrating sphere 1 is coated with a diffuse reflection coating 2; the integrating sphere 1 is provided with an earth light gathering port 3, a sunlight incident port 4 and a detector interface 5; the ground light gathering port 3 is connected with the light gathering system 6, and a first electromagnetic valve 11 is arranged between the ground light gathering port 3 and the light gathering system 6; the sunlight incident port 4 is provided with a second electromagnetic valve 12; the detector interface 5 is provided with a collimation correction module and a detector module; incident light rays of the ground light-gathering port 3 and the sunlight incident port 4 enter the integrating sphere, are reflected for multiple times by the diffuse reflection coating 2, form a uniform illumination surface on the inner surface of the integrating sphere, and are guided into the detector module through the collimation correction module of the detector interface 5.
The collimation and correction module comprises a field diaphragm 7 and a correction and collimation lens 8, the correction and collimation lens 8 is arranged in the field diaphragm 7, and light enters the correction and collimation lens 8 from the detector interface 5 and then is guided into the detector module; the detector module comprises an optical filter 9 and a detector unit 10, light is guided into the detector unit 10 after passing through the optical filter 9, and the detector unit 10 is an InGaAs detector.
Wherein, the light-gathering system 6 is a reflective structure.
The InGaAs detector is an integrated detector and integrates at least 1 pixel.
Wherein, the incident flux of the ground light gathering port 3 is equal to the incident flux of the sunlight incident port 4, because
Flux of sunlight incident port of
Wherein the content of the first and second substances,
solar irradiance outside the atmosphere, bλIs the bandwidth, theta is the angle of incidence of the sunlight, DsThe aperture of the sunlight incident port;
incident flux to the ground light-gathering opening is
Wherein the content of the first and second substances,
in order to obtain the upward atmospheric transmittance,
for the down-bound atmospheric permeability, ρ (λ) is the ground reflectivity, τ0(lambda) is the transmittance of the ground observation light-gathering system, omega is the solid angle formed by the height of the track and the ground, DoThe aperture of the ground light-gathering port;
when in use
The relationship between the aperture of the sunlight incident port and the aperture of the ground light gathering port is as follows:
example two
A radiometer for remote sensor on-orbit atmospheric calibration, as shown in FIG. 2, comprises an integrating sphere 1, the inner surface of the integrating sphere 1 is coated with a diffuse reflection coating 2; the integrating sphere 1 is provided with a ground light-gathering port 3, a sunlight incident port 4 and two detector interfaces 51 and 52; the ground light gathering port 3 is connected with the light gathering system 6, and a first electromagnetic valve 11 is arranged between the ground light gathering port 3 and the light gathering system 6; the sunlight incident port 4 is provided with a second electromagnetic valve 12; the detector interfaces 51 and 52 are both provided with a collimation correction module and a detector module; incident light rays of the ground light gathering port and the sunlight incident port enter the integrating sphere, are reflected for multiple times through the diffuse reflection coating, form a uniform illumination surface on the inner surface of the integrating sphere, and are guided into the detector module through the collimation correction modules of the detector interfaces 51 and 52.
The first collimation correction module at the detector interface 51 comprises a first field diaphragm 71 and a first collimation correction lens 81, the first collimation correction lens 81 is arranged in the first field diaphragm 71, light enters the first collimation correction lens 81 from the detector interface 51 and then is guided into the first detector module, the first detector module comprises a first optical filter 91 and a first detector unit 101, the light is guided into the detector unit 101 through the optical filter 91, and the detector unit 101 is an InGaAs detector; the second collimation and correction module at the detector interface 52 includes a second field diaphragm 72 and a second collimation and correction lens 82, the second collimation and correction lens 82 is disposed in the second field diaphragm 82, light enters the second collimation and correction lens 82 from the detector interface 52 and then is guided into the second detector module, the detector module includes a second optical filter 92 and a second detector unit 102, the light is guided into the detector unit 102 through the optical filter 92, and the detector unit 102 is a Silicon detector.
The InGaAs detector is an integrated detector and integrates at least 1 pixel.
Wherein the incident flux of the ground light-gathering port 3 is equal to the incident flux of the sunlight incident port 4, so that
Flux of sunlight incident port of
Wherein the content of the first and second substances,
solar irradiance outside the atmosphere, bλIs the bandwidth, theta is the angle of incidence of the sunlight, DsThe aperture of the sunlight incident port;
incident flux to the ground light-gathering opening is
Wherein the content of the first and second substances,
in order to obtain the upward atmospheric transmittance,
for the down-bound atmospheric permeability, ρ (λ) is the ground reflectivity, τ0(lambda) is the transmittance of the ground observation light-gathering system, omega is the solid angle formed by the height of the track and the ground, DoThe aperture of the ground light-gathering port;
when in use
The relationship between the aperture of the sunlight incident port and the aperture of the ground light gathering port is as follows:
a measurement method based on the radiometer for remote sensor on-orbit atmospheric correction comprises the following steps:
1) self-calibration of radiometer: determining the relative attenuation of the radiometer by adopting the ratio of the output average value of the radiometer to the daily observation detector when the remote sensor passes through a certain solar altitude in the orbital motion to the output average value of the radiometer to the daily observation detector when the remote sensor passes through the same solar altitude in the orbital motion;
the average value of the output of the detector is the time t from the sun altitude α to the sun altitude β when the remote sensor runs in the track, the first electromagnetic valve is utilized to close the ground light gathering port, the second electromagnetic valve is opened to enable the sunlight incident port to observe the sun, the incident light enters the integrating sphere and then is reflected for multiple times by the diffuse reflection coating, a uniform illumination surface is formed on the inner surface of the integrating sphere, and the average value of N times of data continuously collected by the detector is used
2) Atmospheric radiation characteristic measurement: when the remote sensor passes through the ground calibration field and is empty, the sunlight incident port is closed by using the second electromagnetic valve, the first electromagnetic valve is opened, the ground light-gathering system is aligned to the central reference area of the calibration field, the light of the calibration field is gathered by the ground light-gathering system, enters the integrating sphere and is reflected for multiple times by the diffuse reflection coating, a uniform illumination surface is formed on the inner surface of the integrating sphere, data are collected by the detector, and the atmospheric transmittance of the central reference area of the calibration field is obtained.
By adopting the technical scheme, the invention has the following advantages:
1) the method takes a stable and known sun as a reference, eliminates the influence of self attenuation and change on calibration precision of a calibration source in principle, can accurately measure atmospheric characteristic parameters above a calibration field, eliminates atmospheric profile errors, and inverts the atmospheric parameters;
2) according to the invention, the correction module is arranged in front of the light-entering detector to solve the problem that the wavelength curve is tilted and widened due to a large refraction angle when the light enters the detector after passing through the integrating sphere, so that the spectral response bandwidth of the detector is ensured, and the calibration of the atmosphere correction radiometer is more accurate;
3) simple structure and good stability.
Drawings
FIG. 1 is a schematic structural diagram of a radiometer according to a first embodiment of the present invention for in-orbit atmospheric calibration of a remote sensor
FIG. 2 is a schematic structural diagram of a radiometer according to a second embodiment of the present invention for in-orbit atmospheric calibration of a remote sensor
FIG. 3 is a schematic structural diagram of a light-collecting system according to an embodiment of the present invention
Detailed Description
In order that the objects, features and advantages of the present invention will become more apparent, a detailed description of one embodiment of the invention is provided below along with accompanying drawings and examples, wherein many specific details are set forth in order to provide a thorough understanding of the invention, but the invention can be practiced in many ways other than as described, and therefore the invention is not limited to the specific embodiments disclosed below.
The specific implementation method is given according to the structural characteristics and the functions of the invention. Radiometer system specifications for remote sensor in-orbit atmospheric calibration are as follows:
| 1 | inner diameter of integrating sphere | 56.0 |
| 2 | Thickness of integrating sphere | 10.0 |
| 3 | Size of sunlight incident port | Ф0.17mm |
| 4 | Size of ground light gathering port | Ф1.54mm |
| 5 | Detector diaphragm size | Si：5×Ф3.2mm；InGaAs：1×Ф8.8mm |
| 6 | Size of photosensitive surface of detector | Ф1.0mm |
The light-gathering system adopts a reflection type structure, as shown in fig. 3, the lens is made of quartz material, and meanwhile, the structure is light and small, and the optical design result is shown in the following chart:
for Si detector, 5 units are independently arranged, and for InGaAs detector, 5 units 1 integral arrangement is adopted. The detector center wavelength settings and received energy are shown in the following table:
incident light rays of a solar light inlet and a ground light gathering port of the radiometer enter the integrating sphere in the integrating sphere and are reflected for multiple times through the diffuse reflection coating, after a uniform illumination surface is formed on the inner surface of the integrating sphere, the incident angle of the light rays reaching a light filter of the detector is larger than 9 degrees, the wavelength curve is easy to warp and widen, and data acquired by the detector is inaccurate, so that a correction collimating lens is arranged in front of the light ray entering detector, and the distance between the correction collimating lens and the light filter is 0.5 mm; after the light leaves the correcting collimating lens, the incident angle of the light reaching the surface of the optical filter of the detector is controlled within 9 degrees, so that the spectral response bandwidth of the detector is ensured, and the calibration of the atmospheric correcting radiometer is more accurate.
A measuring method of a radiometer for remote sensor on-orbit atmospheric correction comprises the following steps:
1) self-calibration of radiometer: determining the relative attenuation of the radiometer by adopting the ratio of the output average value of the radiometer to the daily observation detector when the remote sensor passes through a certain solar altitude in the orbital motion to the output average value of the radiometer to the daily observation detector when the remote sensor passes through the same solar altitude in the orbital motion;
wherein the average value of the output of the detector is within 2min from the sun altitude of-2 degrees to the sun altitude of +4 degrees (near the arctic shadow region) when the remote sensor runs in the track,the earth light gathering port is closed by the first electromagnetic valve, the second electromagnetic valve is opened to enable the sunlight incident port to observe the sun, the incident light enters the integrating sphere and then is reflected for multiple times by the diffuse reflection coating, a uniform illumination surface is formed on the inner surface of the integrating sphere, and then the average value of 10 times of data continuously collected by the detector is obtained
2) Atmospheric radiation characteristic measurement: when the remote sensor passes through the ground calibration field and is empty, the sunlight incident port is closed by using the second electromagnetic valve, the first electromagnetic valve is opened, the ground light-gathering system is aligned to the central reference area of the calibration field, the light of the calibration field is gathered by the ground light-gathering system, enters the integrating sphere and is reflected for multiple times by the diffuse reflection coating, a uniform illumination surface is formed on the inner surface of the integrating sphere, data are collected by the detector, and the atmospheric transmittance of the central reference area of the calibration field is obtained.
According to the relative relation between the reference area of the center of the calibration field and the orbit, the satellite laterally swings within the range of +/-10 degrees for different calibration time points. Considering the influence of drift angle, the accuracy required by the side-sway angle is better than 0.1 degrees, namely the positioning accuracy of the acquisition area of the atmospheric correction radiometer is better than 1.54 km.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. A radiometer for remote sensor in-orbit atmospheric calibration, characterized by: the radiometer comprises an integrating sphere, wherein the inner surface of the integrating sphere is coated with a diffuse reflection coating; the integrating sphere is provided with a ground light gathering port, a sunlight incident port and at least one detector interface; the ground light gathering port is connected with the light gathering system, and a first electromagnetic valve is arranged between the ground light gathering port and the light gathering system; the sunlight incident port is provided with a second electromagnetic valve; the detector interface is provided with a collimation correction module and a detector module; the incident light of the ground light gathering port and the sunlight incident port enters the integrating sphere and is reflected for multiple times by the diffuse reflection coating, a uniform illumination surface is formed on the inner surface of the integrating sphere, and the uniform illumination surface is led into the detector module through the collimation correction module of the detector interface.
2. A radiometer for remote sensor in-orbit atmospheric calibration, according to claim 1, wherein: the light condensing system is of a reflective structure.
3. A radiometer for remote sensor in-orbit atmospheric calibration, according to claim 1, wherein: the collimation and correction module comprises a field diaphragm and a correction and collimation lens, the correction and collimation lens is arranged in the field diaphragm, and light enters the correction and collimation lens from a detector interface and then is guided into the detector module.
4. A radiometer for remote sensor in-orbit atmospheric calibration, according to claim 1, wherein: the detector module comprises an optical filter and a detector unit, and light rays are guided into the detector unit after passing through the optical filter.
5. A radiometer for remote sensor in-orbit atmospheric calibration, according to claim 4, wherein: the detector unit is an InGaAs detector.
6. A radiometer for remote sensor in-orbit atmospheric calibration, according to claim 5, wherein: the InGaAs detector is an integrated detector and integrates at least 1 pixel.
7. A radiometer for remote sensor in-orbit atmospheric calibration, according to claim 4, wherein: the detector unit is a Silicon detector.
8. A radiometer for remote sensor in-orbit atmospheric calibration, according to claim 1, wherein: the incident flux of the ground light gathering port is equal to that of the sunlight incident port
Flux of sunlight incident port of
Wherein the content of the first and second substances,
solar irradiance outside the atmosphere, bλIs the bandwidth, theta is the angle of incidence of the sunlight, DsThe aperture of the sunlight incident port;
incident flux to the ground light-gathering opening is
Wherein the content of the first and second substances,
in order to obtain the upward atmospheric transmittance,
for the down-bound atmospheric permeability, ρ (λ) is the ground reflectivity, τ0(lambda) is the transmittance of the ground observation light-gathering system, omega is the solid angle formed by the height of the track and the ground, DoThe aperture of the ground light-gathering port;
when in use
The relationship between the aperture of the sunlight incident port and the aperture of the ground light gathering port is as follows:
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| CN112284533A (en) * | 2019-07-24 | 2021-01-29 | 中国科学院上海技术物理研究所启东光电遥感中心 | Radiometer for remote sensor on-orbit atmospheric correction |
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| CN112284533A (en) * | 2019-07-24 | 2021-01-29 | 中国科学院上海技术物理研究所启东光电遥感中心 | Radiometer for remote sensor on-orbit atmospheric correction |
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Address after: 226200 building 11, Jinmeng Pioneer Park, 101 Nanhai Road, high tech Zone, Qidong City, Nantong City, Jiangsu Province Patentee after: Qidong Zhongke photoelectric remote sensing center Address before: 226200 building 11, Jinmeng Pioneer Park, 101 Nanhai Road, high tech Zone, Qidong City, Nantong City, Jiangsu Province Patentee before: QIDONG PHOTOELECTRIC AND REMOTE SENSING CENTER, SHANGHAI INSTITUTE OF TECHNICAL PHYSICS OF THE CHINESE ACADEMY OF SCIENCES |
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