摘要 :
Im Rahmen von gro?r?umigen geometrischen Fragestellungen ist die satellitenbasierte Radarfernerkundung zu einem Standardverfahren geworden und wird mittlerweile im Bereich der Erfassung von Bodenbewegungen auf Bundes- bzw. Landere...
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Im Rahmen von gro?r?umigen geometrischen Fragestellungen ist die satellitenbasierte Radarfernerkundung zu einem Standardverfahren geworden und wird mittlerweile im Bereich der Erfassung von Bodenbewegungen auf Bundes- bzw. Landerebene genutzt. Wesentlich kleinr?umigere Untersuchungsgebiete wie Hangrutschungen, Boschungsbewegungen, Setzungen von Bauwerken oder Deformationsmessungen im Bereich des Tunnelbaus, der Dammüberwachung oder der Stabilit?tsuntersuchungen von Brücken fallen in den Bereich der Ingenieurgeod?sie und k?nnen teilweise auch mit radarinterferometrischen Verfahren beobachtet und überwacht werden. In diesem Beitrag soll auf die grundlegenden Messmethoden der satellitengestützten und terrestrischen Radarinterferometrie für die Anwendung in der Ingenieurgeod?sie eingegangen und das Anwendungspotenzial für Fragestellungen in der Ingenieurgeod?sie an einigen Beispielen dargestellt werden.
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A new algorithm is proposed for solving the problems associated with discontinuity sources in phase maps. It is based on the stable-marriages algorithm and is implemented as a recursive procedure. With this technique, discontinuit...
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A new algorithm is proposed for solving the problems associated with discontinuity sources in phase maps. It is based on the stable-marriages algorithm and is implemented as a recursive procedure. With this technique, discontinuity sources of opposite sign are connected by a set of cut lines that fulfills a stability criterion and possesses the minimum cut length of the stable sets. The algorithm is fast and easy to implement and has proved efficient, as experimental results show. [References: 11]
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Correlations between photon currents from separate light-collectors provide information on the shape of the source. When the light-collectors are well separated, for example in space, transmission of these currents to a central co...
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Correlations between photon currents from separate light-collectors provide information on the shape of the source. When the light-collectors are well separated, for example in space, transmission of these currents to a central correlator is limited by band-width. We study the possibility of compression of the photon fluxes and find that traditional compression methods have a similar chance of achieving this goal compared to compressed sensing.
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The use of polarization sensitivity Digital Speckle Pattern Interferometry (DSPI) technique as a new alternative to characterize surface behavior is proposed. The method is based on the visibility fringes dependence on the way eac...
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The use of polarization sensitivity Digital Speckle Pattern Interferometry (DSPI) technique as a new alternative to characterize surface behavior is proposed. The method is based on the visibility fringes dependence on the way each surface depolarizes the incident laser light. [References: 16]
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A modified Michelson interferometer with external electrooptic phase control is presented. The device is a polarization interferometer, in which the reference and test arms are parts of the same collimated beam. The reference wave...
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A modified Michelson interferometer with external electrooptic phase control is presented. The device is a polarization interferometer, in which the reference and test arms are parts of the same collimated beam. The reference wave undergoes an odd number of reflections while the test wave is reflected an even number of times. As a consequence, the elliptical state of polarization of the reference wave will have opposite handedness in comparison with the state of polarization of the wave traveling through the test object. The phase shift between the two waves is externally controlled with a Pockels cell. This allows to make a very fast phase modulation. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 12]
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In most speckle shearing intrferometers image shearing is performed by means of a Michelson interferometer or by means of a wedge prism covering half of the aperture of the Camera objective. We present a speckle shearing interfero...
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In most speckle shearing intrferometers image shearing is performed by means of a Michelson interferometer or by means of a wedge prism covering half of the aperture of the Camera objective. We present a speckle shearing interferometer which utilizes a microprism Array of this purpose. It is placed between the test specimen and the camera. In comparision With a wedge prism it exhibits some advantages: it needs no exact alignment, it works with any Camera lens, the shearing distance and direction of shearing can be easily changed by changing Position(resp. Angular orientation)of the element.
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A simple model is used to show that control of dispersion in an all-fiber stellar interferometer is feasible. From the results we assume that an interferometer control system is available in which both temperature and strain are u...
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A simple model is used to show that control of dispersion in an all-fiber stellar interferometer is feasible. From the results we assume that an interferometer control system is available in which both temperature and strain are used to balance the interferometer. Within the restriction of a single polarization mode, it is shown that vacuum path errors before the coupling of starlight into the fibers as well as fiber-length differences and environmental differences between two fibers can be corrected to high order. [References: 17]
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A method for measuring a phase difference between two interfering wavefronts on the basis of analyzing the trajectories that are formed by the intensities of pairs of points in a series of interferograms with different phase shift...
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A method for measuring a phase difference between two interfering wavefronts on the basis of analyzing the trajectories that are formed by the intensities of pairs of points in a series of interferograms with different phase shifts is proposed. This method does not require a priori knowledge of the actual values of phase shifts.
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The effectiveness of phase-shifting interferometry (PSI) techniques employing piezoelectric device PZT in the estimation of phase depends largely on the accuracy with which the phase shifts are imparted to the device and the noise...
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The effectiveness of phase-shifting interferometry (PSI) techniques employing piezoelectric device PZT in the estimation of phase depends largely on the accuracy with which the phase shifts are imparted to the device and the noise influencing the measurement. Several effective algorithms have been proposed to compute the phase shifts imparted to the device and subsequently obtain the phase using least-squares estimation technique. In this paper, we propose a generalized approach, which accurately estimates the phase shifts in the presence of noise. The method is based on the idea of linear prediction and explores the fact that sampling more data frames yields a reliable phase step estimate in a least-squares sense. We also compare our method with a commonly used generalized phase-shifting method based on histogram analysis and show that our proposed approach is highly effective. We also present simulation and experimental validations of our proposed method.
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Lateral shear interferometry is used to obtain the lateral aberrations of a lens. The zeroth-order fringe in an interferogram obtained from a wedge-plate lateral shear interferometer, however, directly displays the lateral aberrat...
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Lateral shear interferometry is used to obtain the lateral aberrations of a lens. The zeroth-order fringe in an interferogram obtained from a wedge-plate lateral shear interferometer, however, directly displays the lateral aberration curve of a test lens. Nevertheless, the intensity distribution, is cosinusoidal. Multiple-beam interferometry results in sharpened fringes; hence the multiple-beam wedge-plate shear interferometer displays the lateral aberration curve of a lens sharply, provided the shear is small. For large shear, some new artifacts appear in the interferogram, which are also explained. [References: 23]
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