FDOCT

FDOCT stands for Fourier-domain Optical Coherence Tomography (also referred to as frequency-domain OCT). It is a family of optical coherence tomography techniques that obtain depth information by analyzing the spectrum of light reflected from a sample, rather than by mechanically scanning a reference path alone. FDOCT encompasses several implementations that share the same fundamental principle of converting spectral interference data into high-resolution, cross-sectional images.

Principle: In FDOCT, a broadband light source illuminates the sample while a reference arm creates interference. The detected interference pattern is recorded as a function of wavelength (spectral-domain OCT) or by using a swept laser (swept-source OCT). A Fourier transform of the interference spectrum yields an axial reflectivity profile, or A-scan; assembling A-scans across lateral positions constructs a B-scan image.

Advantages and scope: FDOCT offers faster imaging and higher sensitivity than traditional time-domain OCT, enabling real-time visualization with greater detail and larger imaging ranges in a single acquisition. Its performance depends on the light source, detection method, and wavelength used. Common clinical and research wavelengths include around 800–900 nm for high-resolution retinal imaging and around 1050–1300 nm for deeper penetration in tissue and thicker samples.

Applications: The technology is widely used in ophthalmology for retinal and optic nerve imaging, dermatology for skin assessment, cardiology and other medical fields, as well as industrial nondestructive testing and materials science.

Variants: The main implementations are spectral-domain OCT (SD-OCT) and swept-source OCT (SS-OCT); both are forms of Fourier-domain OCT and are frequently referred to collectively as FD-OCT. In practice, FD-OCT and SD-OCT are often used interchangeably in literature.