Diffusion-sensitive Fourier-domain optical coherence tomography

Diffusion-sensitive optical coherence tomography (DS-OCT) is presented as a functional extension to OCT. Fluctuations of signal intensity and phase, which are caused by Brownian motion, are analysed by an autocorrelation function similar to dynamic light scattering measurements. Based on an ultra-fast Fourier-domain OCT, DS-OCT can determine quantitatively diffusion properties with high depth resolution, e.g. the hydrodynamic diameter of colloidal suspensions . Performance of DS-OCT is demonstrated with polystyrene particle suspensions and compared to conventional DLS measurements. Applications for DS-OCT may be found in the measurement of particle size distributions of inhomogeneous samples or measurements of diffusion properties at boundary surfaces. Additionally, the method has the capability to become a useful benefit in clinical diagnostics, especially in ophthalmology, where the molecular compositions and pathological changes of anterior eye components could be detected.