Design and measurement of a full-stokes spectro-polarimeter with KD~*P crystals for land objects

摘要

The polarization measurement instrument of land objects is a key element of the polarization remote sensing research, especially for the polarized spectral measurement. The current non-real time and partial polarization spectral measurement cannot meet the need of study. In this paper, a real time full-Stokes spectro-polarimeter with Deuterated Potassium Dihydrogen Phosphate (KD~*P) crystals was developed in lab. The polarimeter, consisting of two KD~*Ps and a fixed retarder and a polarizer, can measure the full Stokes vector with a flexible modulation frequency 1Hz-1kHz, and has the balanced polarimetric efficiencies at a wide spectra band of 400-900 nm. The polarimeter was calibrated with an instrument calibration unit (ICU) to determine the instrument matrix X of each band using a non-linear least square fitting method, the results showed that the measuring accuracy of the full-Stokes spectro-polarimeter is better than 0.02 over the entire spectra band after calibration. Besides, Rohdea japonica is measured and analyzed to obtain their full polarization properties, and the results demonstrated that the circular polarization parameter V is not small enough to be neglected but show significant band features.