Unfolding displacement measurement method for the aliasing interferometer signal of a wavelength-comb-swept laser

We demonstrate an unfolding displacement measurement method to overcome the aliasing problem of wavelength-comb-swept laser (WCSL). Compared to the conventional wavelength-swept laser (WSL), the WCSL exhibits an extended coherence length, owing to the narrowing spectral linewidth of the etalon filter. However, the aliasing interference signal induces an unexpected back-bounced phenomenon during displacement measurement because of the discretely distributed comb-like periodic spectra of the etalon filter. By using the dual-reference interferometry method, the back-bounced displacement measurement can be successfully unfolded to extend the measurement range by two times. In addition, we demonstrate a longer-range surface profiling image over 18 mm within the 200 mm of measurement range using a line-field beam of a parallel-swept source-optical coherence tomography system. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement