Comparison of OCT and LDV for surface vibration measurements and implications for surface wave elastography in multilayered tissues such as skin

Phase-sensitive optical coherence tomography (PhS-OCT) enables depth-resolved measurements of nanometerscale displacements and is increasingly used for optical coherence elastography (OCE). Laser Doppler vibrometry (LDV), in contrast, provides highly sensitive measurements of surface vibration but lacks depth resolution. In this study, displacement measurements obtained with PhS-OCT are compared with LDV using two experimental configurations: (i) controlled excitation of the top surface of a piezoelectric transducer (PZT) and (ii) measurement of surface wave vibrations generated by the PZT on a tissue-mimicking silicone phantom. Finally, the implications of this comparison are discussed in the context of surface wave elastography in layered soft tissues such as skin. In particular, the respective advantages and limitations of LDV and OCT are considered with regard to sensitivity for surface vibration measurements and the ability to obtain subsurface structural information such as layer thickness. These considerations are related to our recent work on multilayer elastography, highlighting the roles of each modality in the biomechanical characterization of skin.