Detecting vibration features from remote objects based on high-speed imagery
Remote detection of vibrational features from an object is important for many short-range civil applications, but it is also of interest for long-range applications in the defense and security areas. The well-established laser Doppler vibrometry technique is widely used as a high-sensitivity, noncontact method. The development of camera technology in recent years made image-based methods reliable passive alternatives for vibration and dynamic measurements. We investigate and discuss the potential of high-speed imaging technique for medium- and long-range vibration detection. The sensitivity and the limitations of the method are experimentally investigated in comparison to the well-established Doppler vibrometry technique. As atmospheric turbulence is expected to become a limiting factor for long-range applications, imaging in the short-wave IR (SWIR) to mid-wave IR (MWIR) rather than in the visual range is advantageous due to the longer wavelength. We present experiments on the vibration detection from SWIR and MWIR image sequences, as well as additional experiments on the extraction of vibration signature under strong local turbulence conditions.