Abstract
Optical coherence tomography (OCT) is a non-contact method for imaging the topological and internal microstructure of samples in three dimensions. OCT can be configured as a conventional microscope, an ophthalmic scanner or endoscopes and small-diameter catheters for accessing internal biological organs. In this Primer, the principles underpinning the different instrument configurations that are tailored to distinct imaging applications are described and the origin of signal, based on light scattering and propagation, is explained. Although OCT has been used for imaging inanimate objects, the discussion focuses on biological and medical imaging. The signal processing methods and algorithms that make OCT exquisitely sensitive to reflections, as weak as just a few photons, and reveal functional information in addition to structure are examined. Image processing, display and interpretation, which are all critical for effective biomedical imaging, are discussed in the context of specific applications. Finally, image artefacts and limitations that commonly arise and future advances and opportunities are considered.