نتایج جستجو برای: interferometry

تعداد نتایج: 11315  

In this paper, we report on the design and fabrication of a low-cost phase shifter for application in phase shifting interferometry. Phase shifting interferometry is a powerful method for surface characterization. It uses interference data recorded during a series of predetermined phase shifts to recover the induced phase by the object surface. These controlled phase shifts are typically perfor...

2006
Ivan Vasconcelos Roel Snieder

Seismic interferometry is a field of growing interest in exploration seismology. In this paper we provide the theoretical basis for performing interferometry by deconvolution. We argue that for general models, deconvolution interferometry gives only the causal scattering response between any two receivers, as opposed to cross-correlation which gives both causal and acausal scattering responses....

2007
Olaf Hellwich

The principles of SAR interferometry and interferogram generation, in particular phase unwrapping and geocoding, are described. Current issues of SAR interferometry are discussed: atmospheric effects on spaceborne repeat-pass interferometry limiting the accuracy and reliability of Digital Elevation Models (DEM), the Shuttle Radar Topography Mission (SRTM) resulting in a globally homogeneous DEM...

1999
Olaf Hellwich

The principles of SAR interferometry, in particular phase unwrapping and geocoding, are described. Interferometric point positioning is treated based on a least squares approach avoiding approximations. Current issues of SAR interferometry are discussed: atmospheric effects on spaceborne repeat-pass interferometry limiting the accuracy and reliability of Digital Elevation Models (DEM), the Shut...

1999
Yunjin Kim Jakob van Zyl Anhua Chu

SAR polarimetry makes use of the polarization dependent scattering response of each pixel within the imaged area. The polarimetric response is highly sensitive to the scattering mechanism of a pixel. SAR interferometry is sensitive to the location of a pixel and its scattering geometry. The location of a pixel can be measured by the phase difference between two coherent SAR images using SAR int...

Journal: :The Journal of the Acoustical Society of America 2013
Giovanni Angelo Meles Andrew Curtis

Source-receiver interferometry allows Green's functions between sources and receivers to be estimated by means of convolution and cross-correlation of other wavefields. Source-receiver interferometry has been observed to work surprisingly well in practical applications when theoretical requirements (e.g., complete enclosing boundaries of other sources and receivers) are contravened: this paper ...

2008
Ivan Vasconcelos Roel Snieder

Interferometry allows for synthesis of data recorded at any two receivers into waves that propagate between these receivers as if one of them behaves as a source. This is accomplished typically by crosscorrelations. Based on perturbation theory and representation theorems, we show that interferometry also can be done by deconvolutions for arbitrary media and multidimensional experiments. This i...

2015
Michael I. Duersch David G. Long

Synthetic aperture radar (SAR) interferometry uses the phase difference between two SAR antennas to obtain an elevation estimate of the imaged terrain. Using an initial digital elevation model (DEM), the time-domain backprojection algorithm implicitly removes the terrain height phase from images during image formation. The use of a DEM during image formation adds additional information to the p...

2010
Yuanzhong Fan James MacNeil Tim Ohno

The phrase virtual source refers to two different techniques in this dissertation. In the first half of the dissertation, it refers to interferometry and in the second half it uses the concept of the synthetic aperture technique. In interferometry, a receiver is converted to a “virtual source”. In the synthetic aperture technique, a large “virtual source” is constructed by adding small sources....

2003
James C. Wyant

The largest limitation of phase-shifting interferometry for optical testing is the sensitivity to the environment, both vibration and air turbulence. In many situations the measurement accuracy is limited by the environment and sometimes the environment is sufficiently bad that the measurement cannot be performed. Recently there have been several advances in dynamic interferometry techniques fo...

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