Development And Detection Of Radiation Calibration Light Source For Spaceborne Shimmer Detector

The spaceborne shimmer detector has been applied to various aspects of environmental observing and production.However,due to the various factors,as the service life increases,its data accuracy will decrease.It needs to be recalibrated and calibrated.Because of the limitation of the calibration light source,the calibration accuracy of traditional methods is generally around 10%.After referring to the successful experience of the radiation calibration light source of the external field shimmer detector,we developed a radiation calibration light source of the external field shimmer detector based on the LED integrating sphere.According to the parameters of the existing shimmer detector,the performance index and system design plan of the integrating sphere light source was proposed,and the feasibility of the plan was demonstrated through the calculation of radiance and uniformity.Integrating sphere used the LED which central wavelength was 670nm as the light-emitting unit.Through the series-parallel connection and gold wire bonding,those LED was integrated packaged into diameter 60mm light platform.A high-precision adjustable voltage power supply and a voltage-controlled constant-current circuit with a dual op-amp structure constituted a high-precision LED drive module.The instability of the drive module was calculated less than 0.1%.Aiming at improving the stability of the LED light-emitting unit when the temperature rises,the customized circulating liquid refrigeration equipment and the designed serpentine cooling block was used to solve the heat dissipation problem.Through the research,QE-Pro high-performance spectrometer was used as the main device to measure the spectral characteristics of the integrating sphere light source.The trap detector which made by three photodiodes was the main body of the stability monitor.Using the C9329 amplifier and data acquisition software to monitor the brightness stability of integrating sphere.Through the investigation,solar lithium batteries was decided as the main power source of the entire system,and gasoline generators was used as backup power sources.To test the light source performance characteristics of the integrating sphere,a large-aperture integrating sphere radiance distribution automatic test system and absolute spectral response rate standard detector was used.The results show that the absolute radiance of the LED integrating sphere was 5.2×10-2 W.cm-z.sr-1;the surface uniformity was better than 99.5%;the angle uniformity within±30° is better than 99.5%;The instability was less than 0.1%and it had excellent radiation characteristics.An external field verification test was conducted in China Remote Sensing Satellite radiometric correction field.The test results show that the stability of the external field radiance can be controlled within 0.1%,and spectral characteristics almost no change.The spaceborne detector result was 8.27×10-9 W·cm-2·sr-1(including moonlight contribution and atmospheric influence),which proves the rationality of the design of the external field low-light calibration light source radiation value.