Determination of the Expanded Optical Transfer Function in Saturated Excitation Imaging and High Harmonic Demodulation

摘要

Most limits of a microscope can be understood in terms of its spatial frequency mapping ability, known as the optical transfer function (OTF). Here, we demonstrate the expansion of the confocal fluorescence microscopy OTF under conditions where the population of excitation states of the sample is saturated. We show how the OTF of saturated excitation can be determined by estimating fluorescence signals using a five-level molecular electronic state model. We then show how modulating excitation and demodulating fluorescence signals can extract high frequency components. We provide experimental validation by demonstrating that harmonic demodulation can extract high frequency OTF components.