Optical coherence tomography

Optical coherence tomography (OCT) uses low-coherence light and interferometry to create cross-sectional images of scattering materials, often at micrometer-scale resolution.

Low-coherence interferometry: Interferometry that uses light with a short coherence length to localize optical path differences. OCT uses short coherence length to select signal from a narrow depth range.
Optical coherence tomography angiography: An OCT method that maps blood flow by detecting motion contrast between repeated scans. It extends structural OCT by visualizing retinal and choroidal microvasculature without injected dye.
Confocal microscopy: A microscopy technique that rejects out-of-focus light using a spatial pinhole to produce optical sections. Both methods section tissue optically, but confocal imaging relies on spatial filtering rather than coherence gating.
Adolf Fercher: An Austrian physicist who helped develop optical coherence tomography and its biomedical applications. His interferometric ranging work supplied key foundations for early OCT.
Multiple scattering: The repeated deflection of waves as they travel through a medium containing many scattering structures. It weakens and distorts OCT signals from deeper tissue, limiting penetration.
Michelson interferometer: An optical instrument that splits light into two paths and recombines them to measure phase or path differences. Many OCT systems compare sample and reference paths using this interferometer's layout.
Retinal imaging: Imaging of the retina, the light-sensitive neural tissue lining the back of the eye. OCT resolves retinal layers in vivo and is widely used to assess eye disease.
Ultrasound imaging: Medical imaging that uses reflected high-frequency sound waves to visualize internal structures. Ultrasound generally penetrates deeper, while OCT resolves finer detail near the surface.
James G. Fujimoto: An American physicist whose group developed and demonstrated biomedical OCT in the early 1990s. His laboratory introduced OCT imaging of biological tissue and helped establish the field.
OCT image segmentation: The computational identification of anatomical boundaries and regions within OCT images. Reliable measurements depend on segmenting layers despite noise, pathology, and image artifacts.

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