Radiometric Calibration Of Satellite-Borne Solar Ultraviolet Spectrum Monitor Before Flight

With the development of remote sensing in our motherland, more and more spectrometers or imaging spectrometers were sent into space, they were widely applied in military and scientific research.Remote sensing in ultraviolet and vacuum ultraviolet can help us recognize many spatial phenomenon, such as dayside and nightside airglow,aurora.So it's very important. In chapter one both development of ultraviolet and vacuum ultraviolet remote sensing in our country and other countries was introduced. Our research process of solar ultraviolet spectrum monitor has three stages from observing on the ground to measuring in a basket carried by a bloon; finally a satellite-borne instrument was launched on Shenzhou spaceship. In chapter two, the structure, working principle, main technical performance, operating mode, and status on orbit were given. How the spectral irradiance and spectral radiance transfer from outside atmosphere to the instrument, further more, through optical elements of the instrument to the detector of the instrument, finally turn into output electric signals are described. Then you have a shematic view of solar ultraviolet spectrum monitor, evaluate the output signal. Because the spectrometer has no inner calibration system at real-time, it has to be calibrated on the ground before being launched. Standard lamp and diffusers are very important calibration elements, in chapter three, first UV and VUV radiometric standard for calibration are introduced. Then the fabrication and characteristics of BaSO4 diffuser and Alminium diffuser are researched, the BaSO4 diffuser's hemispheric reflectance and bi-directional reflectance distribution function were measured and compared with Lambtian surface, and the deviation from that of Lambtian surface is given. In the experiment, Al diffuser's BRDF is researched, obtain the change of spectral characteristic of Al diffuser, compare Al diffuser's BRDF before and after coated with Al+MgF2, and different Al diffusers with different surface roughness. The empirical formula of BRDF changes with different incident angles is fitted according to the experiment data.In chapter four, the solar ultraviolet spectrum monitor was calibrated. First, the apparatus of spectral irradiance calibration is set up, and ultraviolet spectrum band uses a standard lamp offered by Standard Metrological Institute of China, while vacuum ultraviolet spectrum uses a deuterium transfer lamp. The spectral irradiance response of solar ultraviolet spectrummonitor is obtained. For the spectral radiance calibration of solar ultraviolet spectrum monitor, a BaSC>4 diffuser is used, and a more accurate calculation for spectral radiance response is given by a integral formula. Process of download signal data from solar ultraviolet spectrum monitor on spaceship obtains measurement results of solar ultraviolet spectral irradiance and solar backscatter spectral radiance.In chapter five, The structure and principle of Hadamard Transform Imaging Spectrometer are deseribed.Method of manufacturing marks, the key element of the spectrometer by applying computer technology lithography is given, practical masks are obtained by this method, errors of the mask that affected the measurement result are modulaton, finally discusses the limitation of Hadamard Transform Imaging spectrometer's application. Chapter six summarizes all the work done in this dissertation and gives some advices about further research in ultraviolet and vacuum ultraviolet spectrometry.