Enhancing the dynamic range of phase-sensitive optical coherence elastography by overcoming speckle decorrelation

Phase-sensitive optical coherence elastography (PhS-OCE) is a high-sensitivity method for measuring internal displacement fields of semi-transparent materials. Although the displacement measurement sensitivity of PhS-OCE reaches sub-nanometer level, the dynamic range of the measured displacements is limited to micrometers due to displacement-induced speckle decorrelation. In this Letter, a displacement tracking method is developed to overcome this limitation. The method uses a subset-based match approach and takes the noise number of the phase difference map as the match quality, which can effectively track both axial and lateral displacements. For validation, the phase changes inside the polymer samples due to the displacements produced by the temperature/mechanical load changing were measured. The results show that many previously undetectable mechanical behaviors can be quantitatively detected after applying the proposed method.