Removing the dichroism and retardance artifacts in a collinear backscattering Mueller matrix imaging system.

In this paper we report a method for removing artifacts caused by the beam splitter in a collinear backscattering Mueller matrix (CBMM) imaging system. As an essential optical component in a collinear back reflection optical path, a 45ϵ,ρ,δ beam splitter has to be used to separate the incident and the reflection beam. Since the beam splitter induces parasitic dichroism and retardance artifacts in both the illumination and detection optical paths, it leads to artifacts in the experimental results of Muller matrix measurements. We examined the influence of the beam splitter to the measured Mueller matrices in detail and reduced those artifacts in the CBMM system by precisely reconstructing the instrument matrix with a numerical calculation method. By measuring three standard samples we can calculate multiple systematic errors and the polarization characteristics of beam splitter in the CBMM system simultaneously. After the calibration, the maximum error in the Mueller matrix elements can be reduced to less than 0.02.