Optical coherence tomography (OCT) is a non-invasive and non-destructive imaging technique that provides real-time, cross-sectional (2D) and sub-surface volumetric (3D) imaging of structural features with micron-level resolution. OCT bridges the gap separating the resolution and imaging depth capabilities of confocal microscopy and ultrasound imaging.

OCT images are generated by analyzing light backscattered from the different features in the sample. To collect a 1D depth scan, often called an A-Scan, the light emitted by the OCT light source is focused to a small diameter spot, positioned on the specimen, and held stationary. OCT imaging is ideal for samples that are partly transparent to this light probe, allowing the light to penetrate into the sample. The OCT system collects and measures the light backscattered by the surface and sub-surface features located along the path of the probe.

The backscattered light and a reference light beam form an interference pattern that is Fourier transformed to produce a 1D depth profile.
2D and 3D images are obtained by scanning the OCT light probe across the surface of the sample while collecting the measured A-Scans into datasets. The 2D scan that produces a cross-sectional image is called a B-Scan. OCT measurements can also be used to perform qualitative and quantitative motion detection through Doppler and speckle variance OCT.

Contact person: Alexander Riess, M.Sc.