OCT Interferogram: Fringe-Resolved Coherence Gating (2D)

This 2D simulator models the raw signal inside an optical coherence tomography system rather than only its final image. As the probe sweeps laterally across a layered tissue sample, each column triggers a simulated reference-arm depth scan that produces a genuine interferometric signal: carrier fringes at the source's optical frequency, appearing only where the reference and sample path lengths match to within the source's coherence length. That raw fringe signal is then quadrature-demodulated on canvas, in real time, using the same in-phase/quadrature lock-in technique real OCT electronics use, to recover the depth-resolved echo strength — which is what actually builds the live B-scan cross-section shown on the right. Adjust the source's center wavelength and bandwidth to watch the fringe spacing and coherence gate change together, switch tissue presets, and use the live trace to see coherence gating happen at the level of individual interference fringes rather than as an already-smoothed curve.