Super oblique incidence interferometer by using antireflection prism with sub-wavelength structure

摘要

A super oblique incidence interferometer is proposed by using an anti-reflection prism with sub-wavelength structure. Since the sensitivity of interferogram depends on incident angle it can be achieved lower than ordinary interferometer. A sub-wavelength structure on the prism works an increasing transmittance under the condition of the vicinity of critical angle. A shape of this structure is a triangle with sub-wavelength order of height and width periodically and works matching a difference reflective index between prism and air. The experimental results of transmittance are agreed well with the calculated results by the rigorous coupled wave analysis. Its incident angle of the oblique interferogram can be achieved at 86 degrees. Simulation and experimental results are shown.