page_title: Optical coherence tomography
section_title: Full-field OCT
hierarchical_section_title: Optical coherence tomography / Theory / Full-field OCT
caption_attribution_description: English: Schematic view of a full-field OCT set-up.
context_page_description: Optical coherence tomography is an imaging technique that uses low-coherence light to capture micrometer-resolution, two- and three-dimensional images from within optical scattering media. It is used for medical imaging and industrial nondestructive testing. Optical coherence tomography is based on low-coherence interferometry, typically employing near-infrared light. The use of relatively long wavelength light allows it to penetrate into the scattering medium. Confocal microscopy, another optical technique, typically penetrates less deeply into the sample but with higher resolution.
  Depending on the properties of the light source, optical coherence tomography has achieved sub-micrometer resolution.
  Optical coherence tomography is one of a class of optical tomographic techniques. Commercially available optical coherence tomography systems are employed in diverse applications, including art conservation and diagnostic medicine, notably in ophthalmology and optometry where it can be used to obtain detailed images from within the retina.
context_section_description: An imaging approach to temporal OCT was developed by Claude Boccara's team in 1998, with an acquisition of the images without beam scanning. In this technique called full-field OCT (FF-OCT), unlike other OCT techniques that acquire cross-sections of the sample, the images are here "en-face" i.e. like images of classical microscopy: orthogonal to the light beam of illumination.
  More precisely, interferometric images are created by a Michelson interferometer where the path length difference is varied by a fast electric component (usually a piezo mirror in the reference arm). These images acquired by a CCD camera are combined in post-treatment (or on-line) by the phase shift interferometry method, where usually 2 or 4 images per modulation period are acquired, depending on the algorithm used.
  The "en-face" tomographic images are thus produced by a wide-field illumination, ensured by the Linnik configuration of the Michelson interferometer where a microscope objective is used in both arms. Furthermore, while the temporal coherence of the source must remain low as in classical OCT (i.e. a broad spectrum), the spatial coherence must also be low to avoid parasitical interferences (i.e. a source with a large size).
caption: Schematic view of a full-field OCT
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