Feasibility considerations for a long-range passive vibrometer

High-framerate imaging enables the long-range characterization of the vibration modes and amplitudes of a passively illuminated structure. The vibration signature arises from modulation of the bidirectional reflection distribution function (BRDF) as the surface normal oscillates with respect to a fixed, directional source. In this paper we consider the instrument design characteristics and environmental factors that limit passive vibrometer performance including BRDF angle sensitivity, receiver spatial resolution, interference from atmospheric scintillation, and intrinsic detector performance. We here identify a sensor architecture that is capable of characterizing surface vibration at amplitudes below 1 mrad root mean square (RMS) and discuss detector technology that can further improve long-range vibrometer sensitivity.