Swept-source optical coherence tomography (SS-OCT) is able to achieve very high scan speeds and is less susceptible to spectral interferogram fringe washout than spectral domain OCT (SD-OCT) [1, 2]. Therefore, it has advantages for both structural and Doppler OCT imaging. However, in some SS-OCT systems, there is uncertainty in trigger timing so that the starting point of the spectral interferogram acquisition changes from cycle to cycle in wavenumber (k) space. For phase-sensitive OCT measurements such as Doppler OCT, this jitter will reduce the precision of phase measurements. In addition, trigger jitter reduces the effectiveness of subtractive removal of fixed-pattern noise artifacts (lines at fixed depths in OCT B-scans) arising from unintended internal reflections from fiber tips and sample/reference arm optics [3].
A few numerical methods have been proposed to improve the phase stability of SS-OCT systems [3-7]. However, these methods typically cannot remove the residual fixed-pattern noise. In one example approach, a method to eliminate residual fixed-pattern noise and improve the phase stability may be performed by resampling the wavenumber using a simultaneously recorded calibration signal from an interferometer [8]. However, such an approach requires another reference calibration signal as well as another digitizer channel. Thus, the system complexity and cost will be greatly increased. In another example approach, a narrow band fiber Bragg grating (FBG) may be used to produce a reference dip in acquired spectral interferograms so that the spectral interferograms can be shifted accordingly [9]. However, introduction of a FBG in such an approach may induce additional power loss and increase system cost.