Rapid angle-resolved low-coherence interferometry measurements

We have developed a novel angle-resolved low coherence interferometry scheme for rapid measurement of depth-resolved angular scattering distributions. These measurements enable the determination of scatterer size via elastic scattering properties. The scheme uses spectral domain measurements where the mixed signal and reference fields are dispersed by an imaging spectrograph to achieve depth-resolved measurements upon Fourier transform of the spectral data. Angle-resolved measurements are obtained by locating the spectrograph slit in a Fourier transform plane of the scattering sample. We discuss the theoretical basis for the measurements and demonstrate the capabilities of the new technique by recording the distribution of light scattered by polystyrene microspheres. The important features of the system include the ability to detect sub-surface scattering distributions and rapid data acquisition with the entire scattering distribution recorded in 40 milliseconds. The data are used to determine the microsphere size with good accuracy. Potential application of the technique to measuring cell nuclei size in living epithelial tissues is discussed.