Stable carrier generation and phase-resolved digital data processing in optical coherence tomography

Abstract

We present a technique for improved carrier generation by eliminating the instability of a mechanical device in favor of an electro-optical phase modulator in the reference arm of an optical coherence tomography system. A greater than threefold reduction in the phase variance between consecutive A-line scans at a repetition rate of 1 kHz was achieved. Stable and reproducible interference fringe generation permits phase-resolved digital data processing. A correction algorithm was applied to the interferometric signal to compensate for the departure of the source spectrum from an ideal Gaussian shape, resulting in up to 8-dB sidelobe suppression at the expense of a 1-dB increase in the noise floor. In addition, we could eliminate completely the broadening effect of group-delay dispersion on the coherence function by introducing a quadratic phase shift in the Fourier domain of the interferometric signal.