About the A-scan: the electronic signals detected by the photoreceiver are processed as A-scan, which represents the reflectivity profile at the specific focal spot of the sample beam.
About B-scan: multiple A-scans are acquired by sweeping in the lateral direction, and thus a two-dimensional cross-sectional image is created.
C-scan: en face images at a fixed axial depth position.
For the spectrum-domain OCT, the reference arm is fixed at a position approximately corresponding to the position of the sample. The spectral interference of the reference beam and the light backscattered from all depths in the sample is dispersed by a spectrometer and collected simultaneously on an array detector.
For the swept-source OCT, the source has narrow instantaneous linewidth but is rapidly swept in wavelength. The reference arm is also fixed, while the interference fringe is detected on a photoreceiver as a function of time.
2.2 Confocal Gating and Lateral Resolution in OCT Systems
2.3 Spatial Coherence Gating in Full-Field OCT Systems
Pay attention to the multiple scattering and crosstalk artifacts mentioned in this section.
2.4 Axial Ranging with Low-Coherence Interferometry
This section gives a derivation of some key parameters of Michelson interferometer.
Notice: what the three components (DC, cross-correlation, autocorrelation) of intensity of “spectral interferogram” actually mean?