A polarization Fizeau interferometer based on birefringent thin film is presented.The interferometer adopts a birefringent thin film to obtain orthogonally polarized and strictly common-path reference and test beams.Advantages include ease of implementation on large-aperture interferometer,measuring test optics from long distance,and achieving high fringe visibility.The phase shift is obtained by combining a quarterwave plate and an analyzer.The concepts illustrated are verified experimentally.
