Imaging of phase fluctuations by optical coherence tomography

Summary form only. Optical coherence tomography (OCT) is a new modality for recording cross sectional images in transparent and semi-transparent structures with high resolution. Conventional OCT is based on the intensity of backscattered light, i.e., it yields the distribution of the backscattering potential within the sample. However, as is known from microscopy, many samples yield only a poor contrast if they are imaged on an intensity basis. These samples may change other properties of the light which can be used for improving the image contrast. We have developed an extension of OCT which allows imaging of slight phase differences occurring between light beams traversing a sample at closely spaced positions. Such phase differences can be caused by refractive index variations within the sample. We show a sketch of the instrument. A low coherence light source illuminates a Michelson interferometer where the beam is split into a reference and a sample beam.