Simultaneous Measurement of Refractive Index and Physical Thickness of Multiple Layers Using the Results of Fourier Domain Optical Coherence Tomography



Amjadi A¹ ; Falavarjani KG² ; Moazami Gudarzi N¹
Source: Iranian Journal of Physics Research Published:2018

Abstract

In the Fourier domain optical coherence tomography, a picture of the optical thickness (multiplication of the refractive index n in physical thickness d) is obtained; e.g. for the retinal layers, it is used to diagnose many diseases throughout the hospitals in the country. In this work, we introduce a method for a discrete and simultaneous measurement of the refractive index and the physical thickness of multiple layers using Fourier domain optical coherence tomography, without additional information regarding the structure of the sample under investigation. In this method, the only input data are the spectrum of the FD-OCT system and the optical thickness of the sample layers (OPLs), asobtained from Fourier transform of interference spectrum. The results of simulation indicate that the accuracy of the extracted parameters depends on the difference in the refractive index of sample interfaces, because the more the difference in the refractive index, the more the optical reflection index. Furthermore, we show that the accuracy of the extracted parameters is influenced by the accuracy of measuring OPLs. So, we introduce a method to optimize the accuracy of parameters in spite of uncertainty in measuring OPLs. Simulation results show that for transparent biological samples merged into the aqueous media, if sample layers have a refractive index less than 1.55, these parameters can be extracted with an error less than 0.001. © 2018, Isfahan University of Technology. All rights reserved.