Detection of birefringence singularity by supercontinuum vector beam.

We demonstrated detection of birefringence singularity on the space-variant retarder with an inhomogeneous birefringence distribution by supercontinuum vector beam. The birefringence measurement by supercontinuum vector beam analysis provides kinematics of a singularity point on the space-variant retarder. We conducted numerical calculations and experiments for proof of principle. The calculated results were characterized by relative positions with (,) between the singularity point and the vector beam. In the experiments, we measured the retardance and the azimuthal angle from intensity profile on a single-shot image captured at wavelengths of =450, 550, and 650 nm. The retardances at =450 and 550 nm were changed from =112 to 131° and from =120 to 152° when the displacement of the space-variant retarder moved from 0 to 350 µm. The measured retardance corresponded with the calculated results in the function of the position of birefringence singularity.