RF properties of circular-ranging OCT signals.

Circular-ranging optical coherence tomography (CR-OCT) systems that use a time-stepped frequency comb source generate interference fringe signals that are more complex than those of a conventional swept-source OCT system. Here, we define a common terminology for describing these signals, and we develop a mathematical framework that relates the radio-frequency (RF) properties of these fringe signals to the parameters of the frequency comb source. With this framework, we highlight non-intuitive mechanisms whereby the design of the frequency comb source can affect imaging performance. We show, for example, that amplitude-pulsed time-stepped frequency comb sources have a sensitivity advantage over constant power time-stepped frequency comb sources. More broadly, this framework and associated terminology provide a foundation on which to design and optimize time-stepped frequency comb sources and systems.