Holographic interferometry (Total 12692 Papers Found)

A unique statistical data analysis method has been developed for reducing nulling interferometry data. The idea is to make use of the statistical distributions of the fluctuating null depths and beam intensities to retrieve the astrophysical null depth in the presence of fluctuations. The approach yields an accuracy much better than is possible with standard data reduction methods, because the accuracy of the null depth is not limited by the sizes of the phase and intensity errors but by the unc ...
The dark-speckle method (Labeyrie 1995) combines features of speckle interferometry and adaptive optics to provide images of faint circumstellar material. We present preliminary results of observations, and simulations concluding to the feasibility of exo-planet imaging from the ground. Laboratory simulations with an avalanche photodiode indicate the detectability of a stellar companion of relative intensity 10 −6 at 5 Airy radii from the star. New, more general, expressions for the signal-to- ...
Pion and kaon correlations in relativistic nuclear collisions are studied in the framework of boost-invariant, cylindrically symmetric hydrodynamics. It is investigated how the inverse widths, Rout, Rside, of the two–particle correlation functions in out– and side–direction depend on the average transverse momentum K⊥ of the particle pair, the initial energy density ǫ0, and the equation of state of the system. The QCD transition leads to a time delay in the expansion of the system and c ...
This paper introduces the innovative concept of multidimensional waveform encoding for spaceborne synthetic aperture radar (SAR). The combination of this technique with digital beamforming on receive enables a new generation of SAR systems with improved performance and flexible imaging capabilities. Examples are high-resolution wide-swath radar imaging with compact antennas, enhanced sensitivity for applications like alongtrack interferometry and moving object indication, and the implementation ...
Hard x-ray nanobeams have become an important tool in modern synchrotron radiation research with applications in many different fields like biology, chemistry, physics and material science. These nanobeams are usually created by focusing undulator radiation with highly specialized nanofocusing optics like reflective Kirkpatrick-Beaz mirror systems, diffractive zone plates or refractive compound lenses to focal spot sizes below 100 nm in diameter. The optics should in the best case not introduce ...
The effective intercept parameter of the two-pion Bose-Einstein correlation function, λ * , is found to be sensitive to the partial restoration of U A (1) symmetry in ultra-relativistic nuclear collisions. An increase in the yield of the η ′ meson, proposed earlier as a signal of partial U A (1) restoration, is shown to create a " hole " in the low p t region of λ *. A comparison with NA44 data from central S+Pb collisions at 200 AGeV is made and implications for future heavy ion experiment ...
A novel approach using differential reception and nulling interferometry is devoted to weak non line of sight (NLOS) signals measurement. Performed either in the spatial domain or in the spectral domain, this method can achieve line of sight (LOS) dimming, and then NLOS emphasis. This operation, tested in the millimeter band, is very relevant for applications requiring phase carrier measurement such as accurate indoor positioning ...
Most acute tympanic membrane perforations heal spontaneously without any residual complication, whereas a fraction transforms into a chronic perforation. The current treatment of a chronic perforation is surgical repair, which is a costly, time consuming and uncomfortable procedure particularly for the pediatric patients. The objective of this thesis is to evaluate the underlying mechanisms of the reparative process in acute and chronic perforations. This is done by monitoring the structural and ...
It has recently been shown that the response to a virtual source in the subsurface can be derived from reflection data at the surface and an estimate of the direct arrivals between the virtual source and the surface. Hence, unlike for seismic interferometry, no receivers are needed inside the medium. This new method recovers the complete wavefield of a virtual source, including all internal multiple scattering. Because no actual receivers are needed in the medium, the virtual source can be place ...
Crosscorrelating wavefields recorded at two receivers to produce data as if one receiver was a source is commonly referred to as seismic interferometry, or the virtual source method. An artifact in seismic interferometry related to critically refracted waves allowed us to estimate the velocity in the refracting layer. In addition, we devised a new semblance analysis on the crosscorrelation of reflection and refraction energy to robustly estimate the depth and velocity of the slow layer, tested w ...
To date, much of the development work associated with polymer optical fibre (POF) applications has been aimed at exploiting the potential of the technology to provide low cost solutions. Here we argue that, in the sensing area at least, POF offers a number of other, more relevant advantages. In this paper we describe work on a range of devices based on photoinscribed gratings and on fibre interferometers, which are designed to take advantage of the unique properties of POF. Introduction At the t ...
Any-order pion inclusive distribution for a chaotic source in high energy collisions are given which can be used in both theory and experiment to analyze any-order pion interferometry. Multi-pion correlations effects on twopion and three-pion interferometry are discussed. PACS number(s): 13.85 Hd, 05.30Jp, 12.40 Ee. Hanbury-Brown and Twiss [1] were the first who applied the Bose-Einstein (BE) correlations to measure the size of distant stars. The method was first applied to particle physics by G ...
Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterise their atmospheres. Darwin is conceived as a space \nulling interferometer" which makes use of on-axis destructive interferences to extinguish the stellar light while keeping the o -axis signal of the orbiting planet. Within the frame of the Darwin program, the European Space Agency (ESA) and the ...
If scattering amplitudes are ordinary complex numbers (not quaternions) there is a universal algebraic relationship between the six coherent cross sections of any three scatterers (taken singly and pairwise). A violation of this relationship would indicate either that scattering amplitudes are quaternions, or that the superposition principle fails. Some possible experimental tests involve neutron interferometry, KS-meson regeneration, and low energy proton-proton scattering. When we progress in ...
The paper discusses the experimental and finite element investigation into the failure mechanisms of uniply graphite-epoxy composite plates with circular holes loaded in uniaxial compression. The effect of hole size on the failure mode is established. Test specimens composed of a single layer of uniply graphite-epoxy sandwiched between two layers of transparent polyetherimide plastic were designed and produced. This unique stacking geometry enabled the investigators to carry out a nondestructive ...
  • ,
  • 2005
Much of our expectation of the future is based on a linear extrapolation from the present. However history tells us time and again that it’s the nonlinearities that make the big differences in predicting the future. New technologies like smart materials, MEMS, micro adaptive flow control, and nanotechnology all have the potential to have a big influence on the future of aeronautics. A forward-looking view of systems that can successfully integrate these technologies is a key part of making the ...
During a seismic swarm masonry buildings suffer stresses which often give rise to permanent deformation and, in extreme cases, lesions, and sometimes unavailability. When a large area is hit by a swarm, the number of buildings affected by this phenomenon, and potentially vulnerable, amounts to several thousand, giving rise to huge monitoring activity needs [1]. According to this reason, we decided to explore the methodology of differential SAR interferometry, which allows, in principle, to detec ...
The implementation of structural health monitoring systems in modern aircraft structures made of carbon fibre reinforced plastics requires a deeper understanding of the propagation of impact generated Lamb waves. In this paper a digital shearing interferometry method is presented that allows visualization of laser generated Lamb waves. The contactless full field measurement of these waves is performed by a Mach-Zehnder interferometer which combines spatial phase shifting technique and shearograp ...
Tides near and under floating glacial ice, such as ice shelves and glacier termini in fjords, can influence heat transport into the subice cavity, mixing of the under-ice water column, and the calving and subsequent drift of icebergs. Freesurface displacement patterns associated with ocean variability below glacial ice can be observed by differencing two synthetic aperture radar (SAR) interferograms, each of which represents the combination of the displacement patterns associated with the time-v ...
Interferometric signals involving speckle waves invariably exhibit phase indeterminations. These indeterminations arise at the zero-intensities of the speckle fields, or singularities, and show themselves as a net loss of modulation depth of the interferometric signals. To bypass the difficulty associated with the processing of low modulated parts of speckle interferometry signals, we propose a novel approach based on the Delaunay triangulation (DT). The method applies in both situations of stat ...
We show that it is possible to image the structure of a distant quasar on scales of ∼ 1 AU by constructing a telescope which uses a nearby dwarf star as its “primary lens” together with a satellite-borne “secondary”. The image produced by the primary is magnified by ∼ 105 in one direction but is contracted by 0.5 in the other, and therefore contains highly degenerate one-dimensional information about the two-dimensional source. We discuss various methods for extracting information ab ...
The Volturno Plain is one of the largest alluvial plain of peninsular Italy. This area is 10 characterized by both natural and human induced subsidence, and is and most susceptible to coastal 11 hazards. The present study is based on post-processing, analysis and mapping of the available 12 Persistent Scatterer interferometry datasets, derived from combination of both ascending and 13 descending orbits of three different SAR satellite systems, during an observation period of almost 14 two decade ...
We investigate and compare the <inline-formula> <tex-math notation="LaTeX">$\varphi $ </tex-math></inline-formula>-optical time domain reflectometry (OTDR) and OTDR-interferometry methods, both using phase demodulation, for distributed acoustic sensing. By theoretical analysis and experiments we show that, while both <inline-formula> <tex-math notation="LaTeX">$\varphi $ </tex-math></inline-formula>-OTDR and OTDR-interferometry give proper instanta ...
This is the second part of an article series where the mechanical and fracture mechanical properties of medium density fiberboard (MDF) were studied. While the first part of the series focused on internal bond strength and density profiles, this article discusses the fracture mechanical properties of the core layer. Fracture properties were studied with a wedge splitting setup. The critical stress intensity factors as well as the specific fracture energies were determined. Critical stress intens ...
Sinkholes are an unpredictable geohazard that endangers life and property in dolomitic terrains. They are a significant threat in Gauteng, South Africa's most populated and urbanized province. Small scale surface subsidence is frequently present prior to the collapse of a sinkhole. Therefore, the presence of precursory surface deformation can be exploited to develop early warning indicators. Spaceborne SAR interferometry is able to monitor small-scale surface deformation over large areas and was ...
ScanSAR interferometry is an attractive option for efficient topographic mapping of large areas and for monitoring of large-scale motions. Only ScanSAR interferometry made it possible to map almost the entire landmass of the earth in the 11-day Shuttle Radar Topography Mission. Also the operational satellites RADARSAT and ENVISAT offer ScanSAR imaging modes and thus allow for repeat-pass ScanSAR interferometry. This paper gives a complete description of ScanSAR and burst-mode interferometric sig ...
In this work, we report the design, fabrication and characterization of novel biochemical sensors consisting of nanoscale grooves and slits milled in a metal film to form planar plasmonic interferometry. By integrating thousands of plasmonic interferometers per square millimeter with a microfluidic system, we demonstrate a sensor able to detect physiological concentrations of glucose in water over a broad wavelength range (400-800 nm). A wavelength sensitivity between 370-630 nm/RIU (RIU, Refrac ...
Continued excessive extraction of groundwater may lead to significant land subsidence, which causes economic loss. The aim of this research is to investigate ground subsidence in several Australian capital cities using the Persistent Scatterer Interferometry approach. Such studies may help improve our understanding of the deformation of terrain and built structures, and evaluate the effectiveness of any measures taken to ease the problem. The Persistent Scatterer Radar Interferometry approach is ...
For development of the Arcan shear test as a standard test specimen for wood, a detailed knowledge of the strain and stress fields at the narrow cross section is required. Current ASTM D143 shear block tests have shown to have a non-uniform state of stress in the shear zone [1]. Previous research in high performance composites has identified that the Arcan specimen develops a near uniform state of shear al the narrow cross section, however, questions remain regarding its’ applicability to wood ...
Whereas the energy loss of ions penetrating cold matter is understood and several theories, codes and tables exist, the interaction with plasma is scarcely investigated and only a few experimental data exist. Therefore the interaction of heavy ions penetrating hot and dense plasma is explored at the GSI Helmholtzzentrum für Schwerionenforschung using powerful lasers to create a plasma and ions from the UNILAC accelerator to probe the target. For the interpretation of the experimental data it is ...
We report on the recording of stabilized running holograms in photorefractive materials with arbitrarily selected phase shift φ between the transmitted and difracted beams propagating along the same direction behind the photorefractive crystal. The dependence of the diffraction efficiency and of the hologram speed on φ , in such stabilized holograms, can be easily measured and used for material characterization. In this communication we applied for the first time this technique for studying an ...
The measurement of thermo-mechanical deformation in C4 interconnect and chip scale packages is a critical metrology problem for IC packaging. The ability to directly measure the deformation of the actual package, without applying special structures for metrology, is a major advantage of optical digital image correlation technology. Cutting edge automated digital image correlation technology allows in-plane deformation and strain to be measured directly at multiple locations on the bare cross-sec ...
A preliminary prototype of spaceborne laser frequency stabilization system for inter-satellite laser ranging missions has been constructed and demonstrated on ground. The system is based on hydroxide-catalysis bonding and fiber optics. The laser frequency control is driven by an in-house-designed digital controller featuring self-analysis and auto-locking functions. Laser frequency noise less than 30 Hz/Hz<sup>1/2</sup> from 0.7 Hz to 10 Hz has been measured by beat note analysis. Th ...
Extensive understanding and management of the thermal-mechanical characteristics of novel packaging designs during the bonding process are indispensable to the realization of the technologies. Thus, this paper attempts to explore the bonding process-induced thermal-mechanical behaviors of an advanced flip chip (FC) electronic packaging. FC packaging employs a novel anisotropic conductive film, which is a thin composite film composed of polymer matrix and thousands of millions of highly oriented, ...
[WASHINGTON] The US Congress told the National Aeronautics and Space Administration (NASA) last week that it must solve its cost problems in building the international space station without raiding funds allocated to science programmes. House of Representatives and Senate appropriations committees granted the agency $148 million beyond its $13.5 billion request for the 1998 fiscal year, which began last week. But they specifically denied a request from NASA to transfer money from the science, ae ...
Due to the capability to provide direct physical measurements, interferometry is among the remote sensing techniques that have most pushed the applications of SAR to a wide range of scientific areas and have provided direct returns for our society in terms of improved security. Repeat pass DInSAR and, more specifically, its evolution to Persistent Scatterers Interferometry (PSI), which allows the accurate localization of ground targets and the monitoring of possible displacements up to a mm/year ...
We present an assessment of stepwise co-registration procedures applied to multitemporal SAR datasets. Images are connected in pairs through a minimum spanning tree structure, obtained by adopting a distance measure which is a function of the expected co-registration quality. Experiments have been performed on a test dataset by a) directly estimating the (a posteriori) co-registration quality over all possible image combinations, b) using an a priori model inspired by similar models for the mult ...
Knowledge of wall vibrations of musical is important for testing the sound quality of a instrument as well as for instrument design. The Chladnis method for observing the eigen modes gives position of nodal lines, but no amplitude instruments particular traditional only the and phase information. Also the technique ~s not suitable for curved surfaces of musical wind instruments. Introduction of these the wind holographic interferometry helped a lot to overcome drawbacks. But this technique has b ...
  • Kanika Goel, Nico Adam,
  • 2013 IEEE International Geoscience and Remote Sensing Symposium - IGARSS
  • 2013
This paper presents the fusion of monostatic repeat-pass and bistatic single-pass SAR data in complex urban environments to improve the results of stacking techniques such as Persistent Scatterer Interferometry (PSI). Addition of a few motion-free and atmosphere-free TanDEM-X data pairs to the existing TerraSAR-X data stack can improve the 3D positioning and deformation monitoring of objects. However, in dense metropolitan areas, the standard TanDEM-X elevation models are inaccurate because of g ...
X-ray grating interferometry, as a powerful nondestructive imaging tool in fields like biology and medical tests, works well with conventional X-ray tubes, and provides three kinds of information, the attenuation image, the phase-contrast image and the dark field image, with higher contrast. However, the limited field of view of the sample due to the limited size of gratings and detector hinders the further application of the technique. In this paper, we report a solution of large view imaging f ...
The feasibility of two types of all-telluride integrated optics devices being able to single-mode guiding of light in the spectral ranges [6 – 11 µm] and [10 – 20 µm], respectively, is demonstrated. The so-called rib waveguides show a several micron thick Te<inf>82</inf>Ge<inf>18</inf> film deposited onto a Te<inf>75</inf>Ge<inf>15</inf>Ga<inf>10</inf> bulk glass substrate by thermal co-evaporation and furthe ...
In this study, a method of computer model calibration, which was proposed by Kennedy & O’Hagan 2001, is applied to quantify the uncertainty arising in the inverse material identification of the solder joint in the microelectronics package subject to a thermal cycle based on the Bayesian framework. A mathematical example is considered to illustrate the concept and the procedure of the calibration approach. A Wire Bonded – Plastic Ball Grid Array (WB-PBGA) package is considered to determine th ...
In this study, experimental data from two artwork specimens was acquired and processed by pulsed phase thermography (PPT) and holographic interferometry. The first specimen was a wood painting with a variety of damages typical of this kind of pieces. A comparative study between thermography and interferometry results showed the potential complementarities of both techniques. The second inspected specimen was a fresco with fabricated inserts inspected by PPT to detect and characterize the subsurf ...
Edge illumination (EI) x-ray phase contrast computed tomography (CT) can provide threedimensional distributions of the real and imaginary parts of the complex refractive index ( δ β = − + n 1 i ) of the sample. Phase retrieval, i.e. the separation of attenuation and refraction data from projections that contain a combination of both, is a key step in the image reconstruction process. In EI-based x-ray phase contrast CT, this is conventionally performed on the basis of two projections acquire ...
We present adaptive optics integral field spectrograph observations of the Z CMa binary in the 6203 Å-6528 Å band with a spectral resolution of 3200 and spatial resolution of 0.24′′, made with the OASIS instrument coupled to the PUE’O bonnette. Using the binary parameters derived from speckle interferometry, we are able to recover the spectrum of each component, in spite of a spatial sampling (0.11′′) similar to the system separation (0.1′′). The component that dominates the opti ...
High-quality freestanding micromirrors consisting of 40 dielectric layers on silicon have been fabricated by ultrashort-pulse laser ablation in combination with laser-assisted wet chemical etching. Backside material removal enables direct access to both faces of the dielectric coating. The amplitude reflectance of the micromirrors has been determined by Fabry–Pérot interferometry; a finesse in excess of 8900 700, corresponding to a reflectivity exceeding 99.95%, has been found. The mechanical ...