Hyperspectral quantitative phase microscopy for decoupling refractive index and thickness of thin transparent samples

Abstract

Quantitative phase microscopy (QPM) is a label-free imaging technique that has revolutionized transparent sample analysis. It offers precise insights into the sub-wavelength morphological composition of the sample by generating quantitative maps of optical path length delay. However, its potential for explicit study of the microscopic composition of the samples is limited by coupled information of refractive index and thickness. In this work, we present a technique that effectively decouples refractive index and thickness from the phase map, using high spectral resolution hyperspectral quantitative phase microscopy in conjunction with the Higher-order Cauchy dispersion equation. The effectiveness of the proposed approach is established through validation on a simulated phase object, where the recovered refractive index and thickness values agree well with the pre-assigned values. Further, the versatility of this technique is demonstrated through successful application to thin transparent industrial objects and biological samples, positioning it as a promising tool for decoupling refractive index and thickness with minimal assumptions for various transparent specimens.