This paper proposes a full-field and simultaneous method to visualize acoustic waves at the surface of granular media, using a three color digital holographic set-up. Experimental results permit the quantification of the response of the medium to an acoustic excitation, and exhibit propagative longitudinal waves, as well as transverse waves. This new approach also permits the measurement of the influence of a small buried obstacle.
This paper proposes a robust method to compensate for the chromatic aberrations induced by the optical elements in
digital color holography. It combines a zero-padding algorithm and a convolution approach with adjustable
magnification, using a single recording of a reference rectangular grid. Experimental results confirm and validate the
This paper proposes a first attempt to visualize and analyze the vibrations propagating at the surface of a human face's
skin induced by a bone conduction device. The proposed method allows the qualitative visualization and quantitative
measurement of the surface movements illuminated by a coherent laser beam. To do this, we developed a new approach
in a so-called "quasi-time-averaging regime" allowing the retrieval of the vibration amplitude and phase from a sequence
of digital Fresnel holograms recorded with a high image rate. The experimental set-up is based on off-axis digital Fresnel
holography and a high power continuous wave laser. The sensor is a high speed CMOS camera permitting recordings
with a high spatial resolution (1024×1024 pixels) up to 2.4kHz. The set-up is able to provide full field measurements in
the frequency bandwidth 100Hz-600Hz. Recording in the quasi-time-averaging regime leaded to the development of a
dedicated algorithm able to extract the vibration using only three holograms from the sequence. The design of the
algorithm depends on the ratio between exposure time and vibration period. Results exhibit propagation of vibrations at
the skin surface, amplitudes being at most at 200nm, and speed velocity can be estimated at each frequency.