Transient vibration measurements using multi-pulse digital holography

Full-field transient vibrometry of the human tympanic membrane by local phase correlation and high-speed holography

“…Existing methods 5,21 based on steady-state measurements estimate a surface wave speed in the 5 to 70 m∕s range, resulting in acoustic delays across the 8-mm-diameter membrane of 110 to 1600 μs. In order to reliably quantify the speed and direction of acoustic energy propagation across the surface of the TM, an acquisition method should allow the capture of at least three instances 22 of the spatiotemporal evolution of the surface waves within the duration of the acoustical delay. Considering a more conservative estimate for acoustic delay (i.e., ∼100 μs), capturing three instances of the propagation of the surface waves would require <33 μs interframe time resulting in minimal sampling rate of 30 kHz.…”

Obtaining four-dimensional vibration information for vibrating surfaces with a Kinect sensor

“…To extend the applications to various kinds of measurement objects, non-contact measurement techniques based on various kinds of optical theories (photo-electricity, structured light, etc) are exploited for obtaining vibration information in many literatures [1][2][3]. These techniques enable researchers to monitor the surface information of the measured objects without contacting the surface, which largely improve the convenience and flexibility of measurement.…”

<title>Combination of pulsed digital holography and laser vibrometry for the 3D measurements of vibrating objects</title>

“…Hence two digital holograms are captured for every illumination direction. The reconstruction of the phase of the object beam is done by using the Fourier Transform method [1][2][3]. The digital reconstruction allows the determination of the complex amplitude of the wavefront of each hologram.…”