Tomographic imaging via spectral encoding of spatial frequency

Abstract

Abstract:Three-dimensional optical tomographic imaging plays an important role in biomedical research and clinical applications. We introduce spectral tomographic imaging (STI) via spectral encoding of spatial frequency principle that not only has the capability for visualizing the three-dimensional object at sub-micron resolution but also providing spatially-resolved quantitative characterization of its structure with nanoscale accuracy for any volume of interest within the object. The theoretical basis and the proof-of-concept numerical simulations are presented to demonstrate the feasibility of spectral tomographic imaging.

Nano-sensitive optical coherence tomography

“…The range of axial spatial frequencies in OCT is limited by spectral bandwidth of the light source and the resolution of spatial frequencies is limited by spectral resolution. It is known that the axial Fourier spectrum of the object is very informative and highly sensitive to structural changes 6 . In conventional OCT, during the inverse Fourier transform to reconstruct the axial profile, the spatial information is integrated and, as a result, reduces the resolution and sensitivity of the OCT .…”

“…In addition to nsOCT the conventional OCT image can be reconstructed. It is important to note that there is a trade-off between the width of sub-bands and the axial size of the voxel of the reconstructed image, with the optimal choice being application specific 6 . Different informative parameters can be extracted from the local axial spatial period profiles to characterize structure, depending on application, and presented as the nsOCT colour image.…”

Nanosensitive optical coherence tomography for the study of changes in static and dynamic structures

“…A theoretical analysis of the possibility of applying this approach to threedimensional images has been conducted [31]. However, despite significant progress in the development of methods for studying the structure of objects at micro- and nanoscales, the investigation of a three-dimensional structure of strongly scattering objects at the nanoscales still represents a serious problem.…”

Fourier phase in Fourier-domain optical coherence tomography

“…Assuming that the sample being probed satisfies the Born approximation [1], the reflection profile corresponding to n s ( z ′) is given by [47,48] $$r_{s}false(z^{\prime }false)=\frac{1}{2}\frac{d\log n_{s}false(z^{\prime }false)}{d{z}^{\prime }}.$$We note that the concept of Born approximation is typically associated with describing the scattering potential of a weakly scattering sample in the setting of diffraction tomography to reconstruct the three-dimensional (3D) refractive index distribution of the sample via far-field measurements of the scattering amplitude [49]. There, the scattering potential F ( r ) characterizes the refractive index distribution of the sample n s ( r ) with respect to the surrounding medium n m ( r ) through the relation $Ffalse(\mathrm{boldr}false)=-k_0^{2}false(\frac{n_s^{2}false(\mathrm{boldr}false)}{n_m^{2}false(\mathrm{boldr}false)}-1false)$ [1,47,50], where $k_0=\frac{2\pi }{{\lambda }_0}$ is free-space wavenumber corresponding to wavelength λ 0 .…”