Measurement of the spatial uniformity of a large field microstructured retarder

We report on experimental characterization of a microstructured optical retarder fabricated using interference lithography technique. The microstructured element is designed to be a quarter-wave plate in visible range. The measurements of retardation distribution were carried out against wavelength in incoherent light using a rotating analyzer technique. We also investigated the dependence of retardation upon angle of incidence for two orientations of the rotation axis. The measurements showed that the birefringent microstructured element is relatively uniform and introduces 70° retardation at = 510 nm.