Optical diffraction tomography (ODT)

Optical diffraction tomography (ODT) is a visible-range version of X-Ray computerized tomography (CT), which can quantitatively measure three-dimensional (3D) refractive index (RI) distribution of samples in non-invasive manner. Since the RI is an intrinsic optical property of material, ODT quantitatively provides the 3D RI distribution of samples without fluorescence staining. Moreover, since the RI value is linearly proportional to mass density of macromolecules inside biological cells and tissues, ODT offers quantitative analysis of biophysical and morphological parameters of the specimens including mass density, cellular dry mass, and cellular volume in high spatial resolution (~ 100 nm in lateral direction, <200 nm in axial direction).

Principle of ODT : Fourier diffraction theorem

  • You can download a recent version of working MATLAB code and a sample data set upon request. Please contact via e-mail.

a, Quantitative phase images of a polystyrene bead with the diameter of 10 μm illuminated at various incidence angles, and corresponding 2D Fourier spectra of complex optical fields. b, Object functions in the 3D Fourier space mapped via Fourier diffraction theorem. Each 2D Fourier spectrum of complex optical field at certain illumination angle can be mapped into the surface of a sphere called Ewald sphere according to Fourier diffraction theorem. Illuminating a sample with hundreds of various incident angles can fill the 3D Fourier space, from which 3D RI distribution of the sample is reconstructed by applying inverse Fourier transform of the Fourier space as c. © Samara National Research University.

Biological applications of ODT

a, Reconstructed 3D refractive index distribution of various biological samples. © Samara National Research University. b-d, Intravital quantitative phase microscopy for imaging individual red blood cells flowing inside mesentery capillaries of live mice. © Macmillan Publishers Limited, part of Springer Nature.

  • You can find more visualized images of 3D RI distribution of various biological cells and tissues in Tomocube Inc., a start-up company that commercializes optical diffraction tomography.