Dynamic Range is an important index to evaluate the performance of scientific CCD imaging system, which reflects the detection capability to the signal. At present, the description of DR is mainly expressed by the ratio of CCD full well capacity to readout noise at home and abroad. On the basis of clarifying the imaging process of scientific CCD, a method that defines linearity critical point as the last point where the Linearity Error doesn't exceed -3%, minimum exposure point as the point where the SNR equals to 1, then precisely expresses and calculates DR is introduced. Afterwards in the lab, 100 light and 100 dark images of CCD at different exposure time are collected by using the integrating sphere and other equipment, the relationship between the signal and exposure time is calculated to find out the linearity critical point and minimum exposure point and calculate the DR of CCD. The result shows that the DR of the measured CCD is 61.76dB, which corresponds to the theoretical analysis and verifies the validity of the test. Finally, the factors influencing the DR of CCD are analyzed, the advice to improve the DR is introduced.
Aerosol Absorbing Index (AAI) can be used for the observation of the absorbing aerosol including dust, biomass burning and volcano ash etc. Recently, with much more aerosol pollution events occurring, atmospheric environment is getting worse in China. The AAI derived from FY-3/TOU has been used for the atmospheric aerosol pollution observation since 2013 by China Meteorological Administration. In this paper, the precision factors analysis of AAI retrieval from TOU is made. Based on the analysis, the wavelengths most suitable for AAI retrieval are 354 nm and 388 nm. Besides, considering the low spatial resolution of TOU (50×50 km2), a modified UV sensor is proposed with characters of much smaller size, higher sensitivity (SNR<4000) and higher spatial resolution (<5 km) which is much more suitable for observing aerosol pollution events, especially in urban areas.