The amplitude and the phase or: Measuring directional and random motion with optical coherence tomography

Optical coherence tomography (OCT) uses a low coherence light source and a Michelson interferometer to measure path-length resolved backscatter profiles of samples with micrometer resolution and up to a few millimeters long. The OCT amplitude is typically used to generate images of the sample. Additionally, the amplitude and the phase of the OCT signal can be used to extract quantitative sample information such as layer thickness, refractive index, and flow. In the medical field, OCT has been applied, e.g., to measure blood flow in the human retina and to visualize tumors.
The emphasis of this thesis lies in exploiting the information carried by the time-dependent OCT amplitude and phase to measure the directional and random motion of a sample. In particular, we report on the development, validation, and application of a model based on the OCT autocorrelation function to extract information about the dynamic parameters of a sample from the time fluctuations of the OCT amplitude and phase. The work presented in this thesis, first, extends the understanding of dynamic fluctuations on the OCT amplitude and phase; and second, it opens up new opportunities and applications of OCT for the study of a range of rheological properties in complex dynamic geometries.