A method for measuring two-dimensional refractive index distribution by using Fresnel equations and phase-shifting interferometry

Abstract

Based tin Fresnel equations and the phase-shifting interferometry, an alternative method for measuring the two-dimensional refractive index distribution of a material is presented. A linearly polarized light passes through a quarter wave-plate and is incident on the tested material. The reflected light propagates through an analyzer, and then the interference signal can be obtained. The special equations to estimate the phase of the interferometric signal can be derived by using Fresnel equations. Next, the associated two-dimensional phase distribution is measured by the four-step phase-shifting interferometry. Then, the measured data are substituted into the special equations derived previously, and the two-dimensional refractive index distribution of the tested material can be obtained.