Polarimetric methods
Figure 1 shows schematic designs of IR-DCP (a) and classical FTIR polarimetry (b). Both methods aim to probe the polarization dependent complex transmission (reflection) coefficients txy = |txy| · exp( Δxy), which describe the progression of incoming y-polarized light into x-polarized light. Both methods are sensitive to the transmission Txy = |txy|2.Classical FTIR polarimetry can acquire relative phase differences for two sets of polarization configurations, such as Δxx – Δyy. For FTIR polarimetric studies of materials with cos Δ ≈ 1 (Δ close to 0 or π), a retarder is required as an additional optical element to achieve sufficiently high accuracy. In contrast, IR-DCP can directly measure absolute phases Δxy.