Lateral shearing interferometer for measuring refractive index of silicon

TLDR: In this article, a simple lateral shearing interferometer is proposed for measuring refractive index of thin parallel plate silicon sample, where the rotating sample works as lateral shear element and the recorded interferometric signal is Fourier transform analyzed and the phase change is determined as a function of the rotating angle.

Abstract: A simple lateral shearing interferometer is proposed for measuring refractive index of thin parallel plate silicon sample. The rotating sample works as lateral shearing element. As the sample rotates a continuous lateral shearing is obtained owing to the change of the optical path difference (OPD) between the transmitted beam and that first reflected by the surface sample. The recorded interferometric signal is Fourier-transform analyzed and the phase change is determined as a function of the rotating angle. If the thickness of the silicon sample is known the method provides accurate measurement of the refractive index. ( Summary only available )