High-sensitive full-range optical vibrometry based on Fourier-domain optical coherence tomography

Optical vibrometery based on low coherence Fourier-domain optical coherence tomography (FD-OCT) technique are well capable for providing depth resolved vibration information in comparison with conventional laser based vibrometery. Recently, there has been growing interest in developing coherence-domain vibrometry for various clinical and pre-clinical applications. However, a major drawback of the conventional vibrometer based on Fourier-domain low coherence interferometry is the complex-conjugate ambiguity. This is because in FD-OCT, the detected real valued spectral interferogram is Fourier transformed to localize the scatter within the sample. The Fourier transform of a real valued function is Hermitian, so the reconstructed image is symmetric with respect to the zero-phase delay of the interferometer, leading to ambiguity in interpretation of the resulted OCT images. In this paper, we introduce a full range optical coherence vibrometry to utilize the whole imaging range of the spectrometer. The mirror image elimination is based on the linear phase modulation of the interferometer's reference arm mirror and with an algorithm that exploits Hilbert transform to obtain full range complex imaging.