Fourier Transform Light Scattering (FTLS)

Fourier transform light scattering (FTLS) is a novel experimental approach that combines optical microscopy, holography, and light scattering for studying inhomogeneous and dynamic media. In FTLS the optical phase and amplitude of a coherent image field are quantified and propagated numerically to the scattering plane. Because it detects all the scattered angles (spatial frequencies) simultaneously in each point of the image, FTLS can be regarded as the spatial equivalent of Fourier transform infrared spectroscopy (FTIR), where all the temporal frequencies are detected at each moment in time.

Figure. a) Spatially resolved phase distribution of red blood cells. The color bar indicates phase shift in radians. b) FTLS scattering phase function associated with the cells in a). The FDTD simulation by Karlsson et al. is shown for comparison (the x-axis of the simulation curve was multiplied by a factor of 532/633, to account for the difference in the calculation wavelength, 633 nm, and that in our experiments, 532 nm). c) Terra-pixel quantitative phase image of a mouse breast tissue slice. Color bar indicates phase shift in radians. d) FTLS angular scattering from the tissue in c. The inset shows the 2D scattering map, where the average over each ring corresponds to a point in the angular scattering curve. The dashed lines indicate power laws of different exponents, as indicated.

References
35. H. Ding, Z. Wang, F. Nguyen, S. A. Boppart, and G. Popescu, "Fourier transform light scattering of inhomogeneous and dynamic structures", Phys. Rev. Lett., 101, 238102 (2008).