Research Of Vacuum Low Background Infrared Radiance Temperature Calibration Method

To calibrate the radiance temperature of Chinese Fengyun Meteorological satellite infrared remote sensing,NIM China proposed domestic remote sensing satellite infrared radiance temperature standard research programs,and established the Vacuum Radiance Temperature National Standard Facility(VRTSF)and Infrared remote sensing radiance temperature standard value transfer system,which protects the effective traceability of the radiance temperature of infrared remote sensing satellites in China.The facility uses a high-resolution Fourier spectrometer and an infrared radiation thermometer with an 8~14 ?m spectral response as value transfer instruments,the 190~340 K vacuum standard blackbody as a radiance temperature source traceability standard,the infrared remote sensing radiance temperature standard measurement system with spectral range from 3 ?m to 1000 ?m is established.This paper systematically introduces the system structure,working principle and calibration process of VRTSF.In this paper,a vacuum infrared radiation thermometer with spectral response range of 8~14 ?m is developed,realize the value transfer of the radiance temperature in the low vacuum background.The radiance temperature of the 190~340 K vacuum standard blackbody is measured under atmospheric and vacuum conditions respectively,and the consistency of the thermometer in the atmosphere and vacuum is verified.Based on the VRTSF,the theoretical model of spectral radiance temperature calibration is established.The model used FTIR spectrometer as the value transfer instrument,realize spectral response 8~16 ?m spectrum radiance temperature measurement,and finish the radiance temperature calibration experiment of XXX blackbody.At the same time,a 8~14 ?m vacuum infrared radiation thermometer is used as the value transfer instrument,the theoretical model of band radiance temperature calibration is established.The thermometer's values are calibrated by the 190~340 K vacuum standard blackbody,and complete the radiance temperature calibration experiment of the FY-2 satellite vacuum calibration blackbody.Based on the calibration requirements of vacuum low background aerospace infrared remote sensing radiance temperature,a high precision vacuum blackbody is developed,which the temperature range between 180 K to 500 K and is used in Infrared remote sensing load calibration.This article introduces its structure and temperature control system,and performances tested under vacuum conditions and in a reduced background environment(liquid-nitrogen-cooled shroud),such as the heating rate and stability of temperature control.At room temperature and atmospheric environment,the major technical indicators of this blackbody,such as the emissivity,uniformity and so on,is measured.The method of the blackbody emissivity measurement based on the controlling surrounding radiation is used.The uniformity of the bottom of the cavity is measured by a standard infrared radiation thermometer.The experiments results show that temperature stability time better than 50 minutes when the heating rate of 1 ? / min,and temperature stability better than 0.01 ? in ten minutes.Blackbody temperature is set at 20 ?,30 ? and 50 ?,the emissivity are 0.9965,0.9966 and 0.9963,respectively;the bottom uniformity of the blackbody cavity is better than 0.03 ?.