A technique for increasing the ranging depth in optical frequency domain imaging utilizing frequency encoding is presented. Ranging depth is enhanced by using two interferometer reference arms with different path lengths and independent modulation frequencies (25 and ). With this configuration, the sensitivity decreases by over a depth range of , approximately a threefold improvement over the conventional optical frequency domain imaging technique. We demonstrate that the reference arm frequency separation, tuning speed, center wavelength, and coherence instantaneous length determine the signal-to-cross-talk ratio.
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