Full-depth spectral domain optical coherence tomography technology insensitive to phase disturbance.

To achieve full-depth spectral domain optical coherence tomography in the case of strong environmental disturbance, the iterative phase-shifting (IPS) method and modified dispersion-coded (MDC) method are proposed in this work. In IPS, the precise amount of phase shift is retrieved by iteration, and the direction of the phase shift is determined by dispersion compensation. Conjugate mirror items and noise can be simultaneously eliminated by two captured interferograms, whereas only one of them can be removed in the traditional phase-shift method with two interferograms. In MDC, they are removed through dispersion compensation and signal extraction with a single interferogram. Full-depth images of a glass slide, an onion, and a live fish eye are obtained by the two methods. The advantages and disadvantages of each method are analyzed and compared. IPS is found to be more effective for removing conjugate artifacts, whereas MDC is more conducive to real-time imaging. For a 2 mm × 3.6 mm image of a fish eye (200 depth scans and 1200 spectral sampling points per depth scan), the mirror image artifact is reduced by 28.55 dB in MDC and 41.53 dB in IPS. Processing times are 5.1 seconds (20 iterations) for the IPS method and 0.91 seconds for MDC.