TANG Xiao,FANG Wei,WANG Yu-peng,YANG Dong-jun,YI Xiao-long.Time constant optimization of solar irradiance absolute radiometer[J].Optoelectronics Letters,2017,13(3):179-183 Time constant optimization of solar irradiance absolute radiometer Author Name Affiliation TANG Xiao  Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China University of Chinese Academy of Sciences, Beijing 100049, China School of Mechanical Engineering, University of South China, Hengyang 421001, China  FANG Wei  Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China  WANG Yu-peng  Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China  YANG Dong-jun  Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China  YI Xiao-long  Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China  Abstract:       We experimentally evaluate and optimize the time constant of solar irradiance absolute radiometer (SIAR). The systemic error introduced by variable time constant is studied by a finite element method. The results shown that, with a classic time constant of 30 s for SIAR, the systemic errors are 0.06% in the midday and 0.275% in the morning and afternoon. The uncertainty level which can be considered negligible for SIAR is also investigated, and it is suggested that the uncertainty level has to be less than 0.02%. Then, combining the requirement of international comparison with these two conclusions, we conclude that the suitable time constant for SIAR is 20 s. Thiswork has been supported by the National Natural Science Foundation of China (No.41474161), and the National High Technology Research and Development Program of China (No.2015AA123703). E-mail:tanggxiao1022@126.com Hits: 3723 Download times: 0 View Full Text    Download reader