High-Resolution Quantitative Phase Microscopy with Second-Harmonic Generation and Structured Illumination from a k -Space Formulation

Abstract

<p>We propose a high-resolution label-free two-dimensional imaging method by introducing second-harmonic generation (SHG) and structured illumination in quantitative phase microscopy (QPM), termed S2QPM, which can achieve a fourfold lateral resolution improvement compared with normal incident illumination for noncentrosymmetric structures. Unlike traditional QPM only obtaining information about the optical path difference, S2QPM can additionally recover structural information from the ?(2) distribution. Analytical solutions for SHG fields are obtained by solving the inhomogeneous and nonlinear Helmholtz equation in the k-space in a both concise and accurate way. With the k-space SHG field solutions for different structured illumination patterns, an object reconstruction model is developed to retrieve the high-resolution normalized ?(2) distributions and quantitative phase maps. We simulate high-resolution reconstructions of the normalized ?(2) distributions and quantitative phase maps using various resolution targets. The lateral resolution improvement is quantified by synthesizing the object spectrum function and profiling resolution targets.</p>