Phase-shifting algorithm to achieve high-speed long-depth-range probing by frequency-domain optical coherence tomography

Abstract

Standard Fourier-domain optical coherence tomography (FDOCT) suffers from the presence of autocorrelation terms that obscure the object information and degrade the sensitivity and signal-to-noise ratio. By exploiting the phase information of the recorded interferograms, it is possible to remove those autocorrelation terms and to double the measurement range. However, standard phase-retrieval algorithms need three to five interferograms. We present a novel technique that shows all the features of complex FDOCT with only two recorded interferograms.

Optical coherence tomography—current technology and applications in clinical and biomedical research

“…FD-OCT allows for very high A-scan rates, because it requires no mechanical scanning of the reference path length. This advantage comes, however, at the cost of higher data processing complexity, limited dynamic range [28], signal decrease with the distance of objects from zero (defined by the reference path length), and signal ambiguity for objects above or below zero which may require additional measures for compensation [29][30][31][32][33][34][35]. The choice between SD-OCT or SS-OCT depends mainly on the operating wavelength range [36].…”

Single-step method for fiber-optic probe-based full-range spectral domain optical coherence tomography

“…They can be categorized into the multi-and single-frame methods. As the multi-frame method, the phase shifting [5][6][7][8][9][10] and the simultaneous multiple detection method [11,12] were researched. For the single-frame method, the BM scan [13] (B-scan: lateral scan, M-scan: reference mirror scan), the B-scan-based Hilbert transform reconstruction [14], and the phase shift between two A-lines [15] methods have been proposed.…”

“…However, it requires several interferograms at the same location to build a single complex A-line, which is time consuming; the two-step phase-shifting method has been adopted particularly because it demands just two interferograms [6,7,9,10]. By utilizing multiple spectrometers [11] or a 3 × 3 coupler [12] for parallel detections, two interferograms of a phase difference could be simultaneously captured.…”

Complex Conjugate Resolved Retinal Imaging by One-micrometer Spectral Domain Optical Coherence Tomography Using an Electro-optical Phase Modulator

“…To eliminate these artifacts, several techniques including phase-shifting methods [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], a polarization based demodulation method [24], and a 3 × 3 fiber coupler based method [25] have been proposed. By obtaining the full complex interferogram, the complex ambiguity problems of SD-OCT can be solved.…”

“…One of the main problems in ophthalmic imaging is the sample motion and that is the reason why this method is not so suitable for in vivo imaging. The two frame method [11,13,16,22] reduces the number of required frames to resolve complex ambiguity making it faster than the phase shifted interferometric method. The drawback of that two frame method is that it requires exact 90 degree phase shift between adjacent frames.…”