Numerical analysis on RSOD-based phase modulation in OCT

Optical coherence tomography (OCT) is an emerging technology for high-resolution bio-medical imaging. The rapid scanning optical delay line (RSOD) has developed basically for depth scanning and dispersion compensation. If the pivot center of the galvamirror in RSOD is offset, phase modulation can be realized, providing a high carrier frequency required for heterodyne detection. However, the size of galvamirror should be increased, leading to lower response for its oscillation and hence a low scanning rate. In this paper we propose to apply a sinusoidal waveform (resonant scan) instead of a triangle waveform (linear scan) to the galvamirror. Numerical analysis on phase modulation by RSOD and successive envelop demodulation under different driving waveform is conducted. We demonstrate that it is possible to improve OCT frame rate by resonant scan without compromising the signal-to-noise performance if complete and accurate envelope demodulation and appropriate signal processing are adopted.