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Proceedings Paper

FDTD based model of ISOCT imaging for validation of nanoscale sensitivity (Conference Presentation)

Paper Abstract

Many of the earliest structural changes associated with neoplasia occur on the micro and nanometer scale, and thus appear histologically normal. Our group has established Inverse Spectroscopic OCT (ISOCT), a spectral based technique to extract nanoscale sensitive metrics derived from the OCT signal. Thus, there is a need to model light transport through relatively large volumes (< 50 um^3) of media with nanoscale level resolution. Finite Difference Time Domain (FDTD) is an iterative approach which directly solves Maxwell’s equations to robustly estimate the electric and magnetic fields propagating through a sample. The sample’s refractive index for every spatial voxel and wavelength are specified upon a grid with voxel sizes on the order of λ/20, making it an ideal modelling technique for nanoscale structure analysis. Here, we utilize the FDTD technique to validate the nanoscale sensing ability of ISOCT. The use of FDTD for OCT modelling requires three components: calculating the source beam as it propagates through the optical system, computing the sample’s scattered field using FDTD, and finally propagating the scattered field back through the optical system. The principles of Fourier optics are employed to focus this interference field through a 4f optical system and onto the detector. Three-dimensional numerical samples are generated from a given refractive index correlation function with known parameters, and subsequent OCT images and mass density correlation function metrics are computed. We show that while the resolvability of the OCT image remains diffraction limited, spectral analysis allows nanoscale sensitive metrics to be extracted.

Paper Details

Date Published: 24 April 2017
PDF: 1 pages
Proc. SPIE 10075, Biophysics, Biology and Biophotonics II: the Crossroads, 100750F (24 April 2017); doi: 10.1117/12.2253058
Show Author Affiliations
Aya Eid, Northwestern Univ. (United States)
Di Zhang, Northwestern Univ. (United States)
Ji Yi, Boston Univ. (United States)
Vadim Backman, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 10075:
Biophysics, Biology and Biophotonics II: the Crossroads
Adam Wax; Vadim Backman, Editor(s)

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