Modeling multiply scattered light in full-field optical coherence tomographic imaging of biological tissues

Abstract

In this work, we have constructed a handheld full-field optical coherence tomography (FFOCT) system with high spatial resolution, and the Michelson interferometer (served as compensating optical path) and Fizeau interferometer (served as detection) were mounted in series in this system. The expressions of the multiple scattered light decomposed as the sum of incoherent and coherent contribution were derived based on the diffusion equation and mutual coherence function, and the variations of resolution with imaging depth were derived by using the model of multiple scattering. Experiments were conducted on samples composed of the USAF 1951 resolution target covered by the onion slice and human finger-skin slice, respectively, to validate and evaluate the accuracy of our model. A method of image restoration is then presented in which the relation between the resolution and measuring depth and the simulated PSF in the absence of multiple scattering are employed. With the help of this method the lateral resolution of 2.2 μm and 3.9 μm were separately achieved in the onion slice (measuring depth of 64 μm) and human finger-skin slice (measuring depth of 60 μm), and more tiny structures in the en face image of human finger-skin and moth wings were visible. In addition, a novel method for estimating the values of mean free path and anisotropy of scattering medium was proposed.