A liquid crystal based polarimetric system, a process for its calibration, and a polarimetric measurement process

摘要

The invention concerns a liquid crystal based polarimetric system, a process for the calibration of this polarimetric system, and a polarimetric measurement process intended for measuring the representative parameters of a sample (7).The polarimetric system contains an excitation section (1) emitting a light beam (2). Said light beam (2) passes through a polarization state generator (4) (PSG) and sent onto a sample (7). After reflection or transmission by the sample (7), the beam goes through an analysis section (3) comprising a polarization state detector (8) (PSD). According to the invention, the PSG and PSD comprise each a first and a second liquid crystal elements (13, 14) LCj (j=1,2) having, for each LCj element of the PSG (respectively for each LCj element of the PSD), an extraordinary axis making an angle θj (resp. θ'j) with respect to the polarization direction (i), and a retardation δj (resp(δ'j) between its ordinary and extraordinary axes, said liquid crystals LCj elements (14) being positioned in reverse order in the PSD with respect to the LCj elements (13) of the PSG.