Mapping the wind over vast ocean areas is a very important practical problem, especially at high winds. Satellite measurements using scattering of electromagnetic waves from the rough ocean surface are extremely useful; however, the cross section for this scattering saturates at high winds, when wind speed measurements are most valuable. On the other hand, the same mechanism that precludes use ...

Aalto University, P.O. Box 11000, FI-00076 Aalto www.aalto.fi Author Kimmo Kokkonen Name of the doctoral dissertation Imaging of Surface Vibrations Using Heterodyne Interferometry Publisher School of Science Unit Department of Applied Physics Series Aalto University publication series DOCTORAL DISSERTATIONS 112/2014 Field of research Applied Physics Manuscript submitted 15 October 2013 Date of ...

Passive seismic methods using earthquakes can be applied for extracting body waves and obtaining information of subsurface structure. To analyze earthquake data, one traditionally uses receiver functions, tomography, and seismic interferometry. In this study, we retrieve reflected body waves by applying seismic interferometry to the recorded ground motion from a cluster of earthquakes. We emplo...

Digitally enhanced heterodyne interferometry is a laser metrology technique employing pseudo-random codes phase modulated onto an optical carrier. We present the first characterization of the technique's displacement sensitivity. The displacement of an optical cavity was measured using digitally enhanced heterodyne interferometry and compared to a simultaneous readout based on conventional Poun...

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The cross-correlation of a diffuse or random wavefield at two points has been demonstrated to recover an empirical estimate the Green's function under wide variety source conditions. Over past decades, practical development this principle, termed ambient noise interferometry, revolutionized fields seismology and acoustics. Yet, because spatial sparsity conventional water column seafloor instrum...

Noise pollution has become one of the most serious problems of our society. Considerable part of unpleasant noise is transmitted into the interior of buildings through large vibrating planar structures windows with poor noise-isolation properties caused by their low flexural rigidity. In this Paper, we demonstrate and analyze a noise shielding using an active acoustic metamaterial (AAMM) with e...

The effect of numerical aperture on the fringe spacing in interferometry is analyzed by the use of wave optics. The results are compared with published experimental results, and the influence of apodization of the wave front is discussed. The effects of central obscuration and surface tilt are also considered.

Despite the strength of seismic interferometry to retrieve new seismic responses by crosscorrelating observations at different receiver locations, the method relies on a number of assumptions which are not always fulfilled in practice. Some practical circumstances that may hamper interferometry by crosscorrelation are: one-sided illumination, irregular source distribution, varying source spectr...