Application of an imaging spectropolarimeter to agro-environmental sciences

Abstract

Hyperspectral analysis of solar rays reflected from the Earth’s surface is expected to play an important role in future Earth observation. Two imaging liquid crystal tunable filter (LCTF) spectropolarimeters for the visible and near-infrared wavelength bands have been developed by NAL over the past several years for such analysis. In order to realize the practical application of these optical sensors, efforts are currently under way to develop them into sensor packages for airborne observation systems. 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, along with its construction. The results of a farm observation conducted using a visible wavelength LCTF imaging spectropolarimeter are then presented by the spectral images of the observed areas as an example of a preliminary application to agro-environmental sciences. The results of a second farm observation conducted using a near-infrared LCTF imaging spectropolarimeter are presented by spectral images of an observed crop specimen, and radiances of solar rays reflected from the specimen are also shown. Finally, the applicability of the LCTF spectropolarimeter to agriculture observation is summarized based on the results of these agricultural observations.