Agro-environment observation using near-infrared LCTF spectropolarimeter

Polarimetric analysis of solar rays reflected from the Earth's surface is expected to play a particularly important role in future Earth environment observation, and an imaging liquid crystal tunable filter (LCTF) spectropolarimeter for the near-infrared wavelength band has been developed by the Japan Aerospace Exploration Agency(JAXA) over the past several years for such analysis. In order to realize the practical application of the optical sensor, efforts are currently under way to develop it into sensor package for airborne observation system. This paper first presents the concept and architecture of an optical observation system using an LCTF spectropolarimeter which is sensitive to radiation in the 650-1100 nm near-infrared wavelength band. The results of farm and grassland observations using a near-infrared LCTF imaging spectropolarimeter are then presented by spectral images of observed crop specimen and grass, and radiances of solar rays reflected from the crop and grass are shown. The results of a measurement of water-purity conducted using models of a ploughed and irrigated rice field are also presented by the spectral radiances of solar rays reflected from such field models. Finally, the applicability of the LCTF spectropolarimeter to agro-environment observation is summarized based on the results of these outdoor experiments.