Thin film retardation plate by oblique deposition

The birefringent property of obliquely deposited metal oxides was studied with a view to applying it to optical retardation plates. By finding favorable conditions to form transparent films of large retardation and low opacity, we developed homogeneous quarterwave plates with a bilayered structure 60 x 250 mm in size and ~3 microm thick on glass substrates. These retardation plates can work with a normally incident light based on form birefringence caused by the characteristic anisotropic microstructure inside the film. They showed promising optical properties which can compete with the conventional types of retardation plate.