High-Precise Retardation Measurement Using A Phase Detection Of Young's Fringes

A method for a phase detection of Young's fringes is applied to a high-precise retardation measurement. A simple common-path polarizing interferometer is used with a birefringent wedge and a polarizer. The birefringent wedge introduces a spatially linear phase difference between orthogonally polarized light and Young's fringes are formed on an image sensor. The phase difference between orthogonally polarized light is proportional to the phase of Young's fringes. Thus, the retardation is equal to the phase change of Young's fringes before and after the insertion of the retarder into the common-path interferometer. The phase of Young's fringes is calculated from Fourier cosine and sine integrals of the fringe profile. , The experimental results for wave plates, a Soleil-Babinet compensator and a Pockels cell are presented with error estimations. The accuracy of the retardation measurement is estimated experimentally to be higher than X/2100.