Abstract
Using a Mueller matrix polarimeter based on liquid crystal cells (1) and the forward polar decomposition (2), we study the evolution of the birefringence property induced by an increasing compression of a Plexiglas sample. We measure the 2D distribution of the relative retardation �, the azimuth angleand the ellipticity angleof the sample. A noticeable advantage of such method is the possibility to map the stress- induced birefringence even if the material used for the reflexion implies partial depolarization of the scattered field. More generally, this method will be particularly useful in experimental situations where the light beam undergoes depolarization and/or dichroism in addition to birefringence effects because classical birefringence measurement methods are not able to perform an efficient discrimination between these 3 effects. Our experiment shows that the Plexiglas sample under investigation exhibits some weak stress-induced elliptic birefringence. According to simple numerical simulations, this observation is explained by the use of a bi-static illumination/detection configuration.
Highlights
There is considerable interest in spatially quantifying the parameters describing optical anisotropy [3,4,5,6,7]
We use Mueller matrix polarimeters composed of a polarization-state generator (PSG) and a polarizationstate analyser (PSA) that respectively generates and analyses the light using four linearly independent states
The Mueller matrix polarimeter is composed of a Polarization State Generator (PSG) that consists of a Glan-Thompson polarizing prism followed by 2 nematic liquid crystals acting as adjustable retardance elements and of a Polarisation State Analyser (PSA) that includes the same components, but with the prism placed before the nematic liquid crystals
Summary
There is considerable interest in spatially quantifying the parameters describing optical anisotropy [3,4,5,6,7]. In order to perform a complete polarimetric characterization of an unknown sample, we need to acquire its Mueller Matrix. For such measurement, we use Mueller matrix polarimeters composed of a polarization-state generator (PSG) and a polarizationstate analyser (PSA) that respectively generates and analyses the light using four linearly independent states. The 16 elements of this matrix characterize the 3 polarimetric properties driving amplitude and/or phase relations between 2 orthogonal polarization states of the electric field scattered by the sample : the birefringence (or retardance) that traduces a dephasing, the diattenuation (or dichroism) that describes a differential attenuation and the depolarization that highlights the phase breaks provoked mainly by multiple scattering
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