CN105157827A - Integrating sphere transmission radiometer for ontrack spectrum radiation absolute calibration for remote sensor - Google Patents

Abstract

An integrating sphere transmission radiometer for ontrack spectrum radiation absolute calibration for a remote sensor belongs to the field of ontrack spectrum radiation calibration for a remote sensor. The radiometer comprises an integrating sphere main body, an optical filter detector module and a photoelectric measuring module. The integrating sphere main body is equipped with two openings inside. Reflected light enters, through the two openings, the optical filter detector module and the photoelectric measuring module that are fixed outside the integrating sphere main body. Diffuse reflection paint coats the inside of the integrating sphere main body. The integrating sphere transmission radiometer has the capability of measuring low-power signals in a highly precise manner, exhibits the stable performance for a long period of time, and can serve as a standard space ontrack traceablility low temperature radiometer. The integrating sphere transmission radiometer has the characteristics of converting a power reference into a radiance reference and exhibiting high resolution and low uncertainty reference transmission, so the problem of high-precision ontrack traceablility to SI spectrum radiance absolute calibration for an imaging spectrometer, a satellite remote sensor load and the like is well solved.

Description

An Integrating Sphere Transmissive Radiometer for Absolute Calibration of Remote Sensor Spectroradiance

technical field

The invention belongs to the field of on-orbit spectral radiation calibration of remote sensors, and relates to an integrating sphere transfer radiometer used for absolute calibration of on-orbit spectral radiation of satellite remote sensors.

Background technique

With the continuous and in-depth research of several major issues such as global warming, high-resolution earth observation, and extreme disaster prediction, the demand for high-quality space remote sensing data that can be traced to a unified radiation reference is becoming more and more urgent. Due to the lack of a high-precision unified radiation reference in the existing satellite optical remote sensing payload spectral radiometric calibration, there are large measurement errors in the remote sensing data of a large number of satellites, which makes it difficult for the existing remote sensing satellites to meet the needs of certain fields such as climate, resources and the environment. scientific data needs. In order to meet the research needs of Earth climate observation, various space missions provide a large amount of observation data, the quality of data and the reliability and sufficiency of published accuracy become the key to the effective use of data. However, in space services, especially for optical sensors, although the ground calibration method before launch is perfect and the calibration accuracy is high, due to the vibration during the launch process and the impact of the space environment after orbiting, the on-orbit radiation scale attenuates and drifts. The transmission chain of the radiation reference was broken, so that the instruments after entering orbit could not be traced to SI (International System of Units of Measurement). In order to improve the accuracy of on-orbit calibration and make its uncertainty level comparable to the first-level standard of the National Metrology Laboratory, it is necessary to establish a space on-orbit radiation reference transfer system that is strictly traceable to SI, thereby establishing data quality and data accuracy. The control system regulates the calibration of remote sensing radiation from the mechanism to ensure that all directly acquired data or active output data can be traced back to SI in a true and effective way. parameters are monitored. Since the total solar irradiance and spectral irradiance can be considered to be stable in a long-term scale, the sun is used as the radiation source of the on-orbit remote sensor, and it is measured by a space cryogenic radiometer, thus forming a traceable SI benchmark delivery system. However, due to the limitation of the volume and weight of the space load, the received solar radiation value is directly limited. When it is applied to the narrow bandwidth spectrum band level, the radiation value is already very weak. How to monitor it and use it for spectral radiation calibration of remote sensors is the key question.

Contents of the invention

In order to solve the problems existing in the prior art, the present invention provides a traceable SI, highly integrated, high-precision measuring integrating sphere transfer radiometer for absolute calibration of remote sensor on-orbit spectral radiation.

The technical solution adopted by the present invention to solve technical problems is as follows:

An integrating sphere transfer radiometer for absolute calibration of remote sensor on-orbit spectral radiation, characterized in that the radiometer includes: an integrating sphere main body, an optical filter detector module and a photoelectric measurement module; two openings are opened inside the integrating sphere main body The reflected light enters the optical filter detector module and the photoelectric measurement module fixed outside the main body of the integrating sphere through two openings; the inside of the main body of the integrating sphere is coated with diffuse reflection paint.

The beneficial effects of the present invention are: the integrating sphere transfer radiometer provided by the present invention for the absolute calibration of the remote sensor's on-orbit spectral radiation will combine the functions of the trap detector standard and the filter radiometer into one, and the structural integration degree High, small and light, suitable for space radiation calibration as an on-orbit payload. The dual-aperture diaphragm design of the present invention can provide a conversion between a power reference and an irradiance reference and a radiance reference. The primary reflective partition used in the present invention cooperates with the paint with high diffuse reflectance and low specular reflectance to realize the high Lambertian uniformity of the incident light at the opening of the photoelectric measurement module and the opening of the optical filter detector. The invention adopts a unique optical modulator system and digital phase-sensitive detection technology in the photoelectric measurement module, and mechanically refrigerates the InGaAs detector to make it work at a low temperature of 240K, and finally realizes 10 ^-13 W level, 10 ⁷ The dynamic measurement range and the lowest measurement power level signal-to-noise ratio can reach 400 high-precision circuit measurement control system. Cooperating with specially selected 15 narrow-band filters and using a smooth interpolation algorithm, the filter detector in the present invention realizes spectral radiation calibration and benchmark measurement covering 300-2500nm solar reflection spectrum with 3-10nm resolution Transmit uncertainty at 0.3% level. To sum up, the integrating sphere transfer radiometer used for the absolute calibration of the on-orbit spectral radiation of satellite remote sensors involved in the present invention has the ability to perform high-precision measurement of low-power signals, and at the same time has the guarantee of long-term stable performance, which can be used for The low-temperature radiometer standard used in space on-orbit traceability, combined with the characteristics of the present invention, which converts power references into radiance references and high-resolution and low-uncertainty level reference transfers, solves the problem of imaging spectrometers and other satellites. The problem of high-precision on-orbit traceable SI spectral radiance calibration for remote sensor payloads.

Description of drawings

Fig. 1 is a structural schematic diagram of the overall system of the integrating sphere radiometer provided by the present invention.

Fig. 2 is a schematic diagram of the signal measurement control circuit inside the optical measurement module in Fig. 1 .

In the figure: 1. The main body of the integrating sphere, 2. The precision field diaphragm, 3. The first aperture barrier, 4. The second aperture barrier, 5. The primary reflection baffle, 6. The opening of the filter detector module , 7. Opening of photoelectric measurement module, 8. Diffuse reflection coating, 9. Photoelectric measurement package, 10. Optical modulator system, 11. The first Silicon and InGaAs detector, 12. The first mechanical refrigeration device, 13. Signal measurement Control circuit, 14, optical filter detector package, 15, optical filter and its rotation device, 16, second Silicon and InGaAs detector, 17, second mechanical refrigeration device.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Referring to Fig. 1, the present invention relates to an integrating sphere transfer radiometer for absolute calibration of on-orbit spectral radiation of satellite remote sensors, mainly composed of an integrating sphere main body, a photoelectric measurement module and a filter detector.

The main body of the integrating sphere includes the integrating sphere cavity 1, the precision field diaphragm 2, the first aperture barrier 3, the second aperture barrier 4, the primary reflection baffle 5, the optical filter detector module opening 6, the photoelectric measurement module opening Hole 7, diffuse reflection paint 8. The precision field diaphragm 2 is assembled at the entrance of the integrating sphere cavity 1, the first aperture partition 3 and the second aperture partition 4 are respectively arranged in the precision field diaphragm 2; the primary reflection baffle 5 is arranged on the filter Between the opening 6 of the detector module, the opening 7 of the photoelectric measurement module and the first reflection surface of the incident light beam, the diffuse reflection paint 8 is evenly distributed on the inner surface of the integrating sphere cavity 1 and the entire surface of the first reflection baffle 5 .

The photoelectric measurement module includes a photoelectric measurement package 9 , an optical modulator system 10 , a first Silicon and InGaAs detector 11 , a first mechanical refrigeration device 12 , and a signal measurement control circuit 13 . The optical modulator system 10 is assembled immediately after the opening 7 of the photoelectric measurement module. The first Silicon and InGaAs detectors 11 are installed on the optical path passing through the optical modulator system 10. The signal measurement control circuit 13 is together with the first Silicon and InGaAs detectors 11. The package, after which the first mechanical refrigeration device 12 is connected and assembled, is located at the tail of the photoelectric measurement package 9 .

The filter detector module includes a filter detector package 14, a filter and its rotation device 15, a second Silicon and InGaAs detector 16, a second mechanical refrigeration device 17. The filter detector package 14 and filter The optical filter and its switching device 15 are installed behind the opening 6 of the detector module, and the second Silicon and InGaAs detector 16 is installed on the optical path after the optical filter and its switching device 15 , the second mechanical refrigeration device 17 is connected to the second Silicon and InGaAs detector 16 and is located at the end of the optical filter detector package 14 .

When a light beam enters the integrating sphere cavity 1 through the precision field diaphragm 2, if the light beam does not completely cover the first aperture barrier 3 and the second aperture barrier 4, the power reference traceability calibration is used; if the beam completely covers The first aperture partition 3 and the second aperture partition 4 use the radiance reference traceability calibration; if only one of the first aperture partition 3 and the second aperture partition 4 is covered, use the irradiance reference traceability target. After the incident light is diffusely reflected for the first time in the integrating sphere cavity 1, part of the reflected light will be blocked by the primary reflection baffle 5, so as to avoid direct incident into the opening 6 of the optical filter detector module and the opening 7 of the photoelectric measurement module, so that After multiple reflections by the diffuse reflection paint 8 , the opening 6 of the detector module and the opening 7 of the photoelectric measurement module will receive light radiation with high Lambertian properties and uniform brightness. As shown in Figure 2, the light incident on the photoelectric measurement package 9 will pass through the optical modulator system 10, the optical modulator system 10 is composed of an optical modulator and a frequency generator, and the rotation frequency of the optical modulator is controlled by the frequency generator. Phase modulation is performed by superimposing a fixed-frequency background signal on the incident light signal. After phase modulation, the light beam is incident on the first Silicon and InGaAs detector 11. Since the energy of the incident light is weak, the preamplifier is used to appropriately amplify the generated electrical signal for easy detection. At the same time, because the incident light is superimposed with phase modulation, the reference signal with the same frequency as the background signal generated by the frequency generator can obtain a measurement signal with a very low noise level after the signal measurement control circuit 13 performs digital phase-sensitive detection and acquisition on it. , combined with the 240K low-temperature environment provided by the first mechanical refrigeration device 12 for the first Silicon and InGaAs detector 11, finally realizes a high-precision detector for the weak spectral radiation covering the 1100nm-2500nm solar reflection spectrum with a resolution of 5-10nm Response calibration, thus using the calibrated detector can calculate the relevant light radiation value (power) incident to the photoelectric measurement module, due to the openings of the filter detector module opening 6 and the photoelectric measurement module opening 7 The areas are the same, so the light radiation value incident on the optical filter detector can be determined accordingly, and then the spectral response calibration of the optical filter detector is performed. The opening 6 of the detector module receives the same uniform light radiation as the opening 7 of the photoelectric measurement module, and then the light incident on the optical filter detector package 14 passes through the optical filter and its rotation device 15, due to the continuous replacement of the optical filter Alternate, so the wavelength radiation in the narrow band range corresponding to 15 different channels is sequentially obtained, such quasi-monochromatic light is finally received by the second Silicon and InGaAs detector 16, and cooperates with the low temperature environment provided by the second mechanical refrigeration device 17, finally Complete the same high-precision weak light signal acquisition and responsivity calibration as the photoelectric test module, and establish the second Silicon and InGaAs detector 16 and the beam power and radiation incident on the integrating sphere cavity 1 through the precision field diaphragm 2 The mathematical relationship between the absolute values of luminance or radiance realizes the on-orbit traceability calibration measurement of the spectral radiation of the satellite remote sensor by using the integrating sphere radiometer involved in the present invention. Utilize the solar radiation of the same path to irradiate on the satellite remote sensor to be calibrated and the integrating sphere transfer radiometer of the absolute calibration of the on-orbit spectral radiation involved in the present invention, the on-orbit spectral responsivity of the satellite remote sensor can be obtained, So that it can get high-precision traceable SI calibration measurement.

The integrating sphere transfer radiometer used for absolute calibration of remote sensor on-orbit spectral radiation of the present invention has high-precision weak optical signal collection capability, very wide spectral coverage and precise measurement and calibration performance, and its structural design features are suitable for use with The on-orbit cryogenic radiometer reference is used together to realize the absolute calibration of the traceable SI on-orbit spectral radiation under the low uncertainty level of the satellite remote sensor.

Claims (10)

1. The integrating sphere transfer radiometer used for the absolute calibration of the remote sensor's on-orbit spectral radiation is characterized in that the radiometer comprises: an integrating sphere main body, an optical filter detector module and a photoelectric measurement module; Two openings are opened, and the reflected light enters the optical filter detector module and the photoelectric measurement module fixed outside the main body of the integrating sphere through the two openings; the inside of the main body of the integrating sphere is coated with diffuse reflection paint. 2. The integrating sphere transfer radiometer for remote sensor on-orbit spectral radiation absolute calibration according to claim 1, characterized in that, the radiometer comprises: a primary reflection baffle; the primary reflection baffle is a semi-circular shape , the entire surface is coated with diffuse reflection paint; it is located inside the main body of the integrating sphere, and is set between the first reflection surface and the two openings after the incident light enters the main body of the integrating sphere; so that the diffuse reflection light of the primary reflection surface cannot enter the two openings. 3. The integrating sphere transfer radiometer for remote sensor on-orbit spectral radiation absolute calibration according to claim 1, characterized in that, the radiometer comprises: a precision field diaphragm; the precision field diaphragm is positioned at the integrating sphere The light entrance of the main body; the first aperture barrier and the second aperture barrier are arranged in the precision field diaphragm. 4. the integrating sphere transfer radiometer for remote sensor on-orbit spectral radiation absolute calibration according to claim 1, characterized in that, the opening diameters of the first aperture partition and the second aperture partition are respectively 10mm and 16mm. 5. The integrating sphere transfer radiometer for remote sensor on-orbit spectral radiation absolute calibration according to claim 1, wherein the optical filter detector module comprises: optical filter and its rotation device, Silicon and InGaAs detector; after the incident light enters the optical filter detector module through the opening, it passes through the optical filter and its rotation device, and sequentially obtains the wavelength radiation corresponding to different channels in the narrow band range, which is received by the Silicon and InGaAs detectors. 6. The integrating sphere transfer radiometer for absolute calibration of on-orbit spectral radiation of remote sensors according to claim 1, wherein the optical filter and its rotation device include 15 central wavelengths in the 300-2500nm band For different narrow-band filters within the range, the narrow-band filters are all set on the conversion device. 7. The integrating sphere transfer radiometer for absolute calibration of remote sensor on-orbit spectral radiation according to claim 6, characterized in that, the central wavelength distribution of the 15 optical filters is: there are 6 in the range of 300-700nm There are 5 in the range of 700nm to 1200nm, and 4 in the range of 1200 to 2500nm. 8. The integrating sphere transfer radiometer for remote sensor on-orbit spectral radiation absolute calibration according to claim 1, characterized in that, the photoelectric measurement module includes: Silicon and InGaAs detectors, optical modulator systems and signal Measurement control circuit: After the incident light enters the photoelectric measurement module through the opening, it is phase-modulated by the optical modulator system and collected by Silicon and InGaAs detectors. After the signal measurement control circuit performs digital phase-sensitive detection and acquisition on it, the noise level is obtained Very low measurement signal. 9. according to claim 1,5 or the described integrating sphere transfer radiometer that is used for remote sensor on-orbit spectral radiation absolute calibration, it is characterized in that, in described optical filter detector module and photoelectric measurement module, all Contains a mechanical refrigeration device connected to Silicon and InGaAs detectors. 10. The integrating sphere transfer radiometer for remote sensor on-orbit spectral radiation absolute calibration according to claim 1, characterized in that, the diameters of the two openings are equal, and the center forms a sandwich with the center of the integrating sphere main body The angle range is 25°～35°.