Literatura científica selecionada sobre o tema "Non-linear interferometry"
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Artigos de revistas sobre o assunto "Non-linear interferometry"
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Paterova, Anna V., Dmitry A. Kalashnikov, Egor Khaidarov, Hongzhi Yang, Tobias W. W. Mass, Ramón Paniagua-Domínguez, Arseniy I. Kuznetsov e Leonid A. Krivitsky. "Non-linear interferometry with infrared metasurfaces". Nanophotonics 10, n.º 6 (22 de março de 2021): 1775–84. http://dx.doi.org/10.1515/nanoph-2021-0011.
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Abstract The optical elements comprised of sub-diffractive light scatterers, or metasurfaces, hold a promise to reduce the footprint and unfold new functionalities of optical devices. A particular interest is focused on metasurfaces for manipulation of phase and amplitude of light beams. Characterisation of metasurfaces can be performed using interferometry, which, however, may be cumbersome, specifically in the infrared (IR) range. Here, we realise a new method for characterising metasurfaces operating in the telecom IR range using accessible components for visible light. Correlated IR and visible photons are launched into a non-linear interferometer so that the phase profile, imposed by the metasurface on the IR photons, modifies the interference at the visible photon wavelength. Furthermore, we show that this concept can be used for broadband manipulation of the intensity profile of a visible beam using a single IR metasurface. Our method unfolds the potential of quantum interferometry for the characterization of advanced optical elements.
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Bakon, Matus, Daniele Perissin, Milan Lazecky e Juraj Papco. "Infrastructure Non-linear Deformation Monitoring Via Satellite Radar Interferometry". Procedia Technology 16 (2014): 294–300. http://dx.doi.org/10.1016/j.protcy.2014.10.095.
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Jundt, G., G. T. Purves, C. S. Adams e I. G. Hughes. "Non-linear Sagnac interferometry for pump-probe dispersion spectroscopy". European Physical Journal D - Atomic, Molecular and Optical Physics 27, n.º 3 (1 de dezembro de 2003): 273–76. http://dx.doi.org/10.1140/epjd/e2003-00275-5.
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Ogushi, Fumitaka, Masashi Matsuoka, Marco Defilippi e Paolo Pasquali. "Implementation of Non-Linear Non-Parametric Persistent Scatterer Interferometry and Its Robustness for Displacement Monitoring". Sensors 21, n.º 3 (2 de fevereiro de 2021): 1004. http://dx.doi.org/10.3390/s21031004.
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To derive surface displacement, interferometric stacking with synthetic aperture radar (SAR) data is commonly used, and this technique is now in the implementation phase in the real world. Persistent scatterer interferometry (PSI) is one of the most universal approaches among in- terferometric stacking techniques, and non-linear non-parametric PSI (NN-PSI) was proposed to overcome the drawbacks of PSI approaches. The estimation of the non-linear displacements was successfully conducted using NN-PSI. However, the estimation of NN-PSI is not always stable with certain displacements because wider range of the velocity spectrum is used in NN-PSI than the conventional approaches; therefore, a calculation procedure and parameter optimization are needed to consider. In this paper, optimized parameters and procedures of NN-PSI are proposed, and real data processing with Sentinel-1 in the Kanto region in Japan was conducted. We confirmed that the displacement estimation was comparable to the measurement of the permanent global positioning system (GPS) stations, and the root mean square error between the GPS measurement and NN-PSI estimation was less than 3 mm in two years. The displacement over 2π ambiguity, which the conventional PSI approach wrongly reconstructed, was also quantitatively validated and successfully estimated by NN-PSI. As a result of the real data processing, periodical displacements were also reconstructed through NN-PSI. We concluded that the NN-PSI approach with the proposed parameters and method enabled the estimation of several types of surface displacements that conventional PSI approaches could not reconstruct.
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Corcoran, T. C., L. L. Connell, G. V. Hartland, B. F. Henson e P. M. Felker. "Down-shifting of high frequency components in non-linear interferometry". Chemical Physics Letters 147, n.º 6 (junho de 1988): 517–24. http://dx.doi.org/10.1016/0009-2614(88)80260-4.
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Bedding, T. R., J. G. Robertson e R. G. Marson. "MAPPIT: Optical Interferometry with Non-Redundant Masks". Symposium - International Astronomical Union 158 (1994): 327–30. http://dx.doi.org/10.1017/s007418090010782x.
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MAPPIT (Masked APerture-Plane Interference Telescope) is an optical interferometer mounted at the coudé focus of the 3.9 m Anglo-Australian Telescope. The instrument, shown schematically in Fig. 1, uses a pupil mask with five apertures of diameter ≲r0. The apertures are arranged in a linear non-redundant array, with the spacings chosen to optimize the spatial frequency coverage (R. G. Marson, these Proceedings).
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Lendiel, Vasyl, Iryna Stepakhno e Leonid Yarovoi. "APPLICATION OF THREE-WAVE HETERODINE INTERFEROMETRY FOR NANORIZED LAYERS THICKNESS MEASUREMENT IN THE PROCESS OF THEIR DEPOSITION". Bulletin of Kyiv Polytechnic Institute. Series Instrument Making, n.º 63(1) (4 de julho de 2022): 39–45. http://dx.doi.org/10.20535/1970.63(1).2022.260636.
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The paper proposes a new method of current measurement of the layer thickness of optical films in the process of their forming, in particular, by the method of vacuum deposition. Such films, among other things, are used to create a variety of optoelectronic devices and optical nanosensors for laboratory research in the chemical and pharmaceutical industries, for environmental monitoring.
We propose a method for measuring the phase of a laser beam, which is based on heterodyne interferometry. The method of heterodyne interferometry in comparison with ordinary interference methods provides better S/N ration results due to the transfer of the investigated signal from the low frequency domain to heterodyne frequency. Our proposed approach is the three-wave heterodyne interferometry (TGI), otherwise - TWI (three waves interference). The TGI method is designed to critically increase the sensitivity to small amplitudes of laser Doppler vibrometers and increase their noise resistance. In interference gauges of optical film thickness, in refractometers, and in many other film thickness gauges as well as in laser Doppler vibrometers the investigated parameter is the phase shift of probing optical radiation. Therefore, the developments of TGI in laser Doppler vibrometers can be used to measure the phase shift.
The analysis of the new method on mathematical model of TGI was provided. We have got the relations of the output signal of a three-wave heterodyne interferometer dependence on the phase shift , as well as on the thickness of optical films and on their refractive index. The simulation results show that for the optoelectronic equipment that provides with an error of up to 10 %, the absolute error of phase shift measurement, compared to the classical heterodyne interferometer, can be reduced to 103 times. The same results applies to the thickness of the optical coating layer.
The paper also analyzes the results of experiments on the use of TGI in laser vibrometers and shows that they indicate the possibility of measuring the phase of optical radiation up to 10-5. The disadvantage of the proposed method is its non-linearity and, as a result, a limited linear range. Ways of extending the linear range are discussed.
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Gerberding, Oliver, e Katharina-Sophie Isleif. "Ghost Beam Suppression in Deep Frequency Modulation Interferometry for Compact On-Axis Optical Heads". Sensors 21, n.º 5 (2 de março de 2021): 1708. http://dx.doi.org/10.3390/s21051708.
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We present a compact optical head design for wide-range and low noise displacement sensing using deep frequency modulation interferometry (DFMI). The on-axis beam topology is realised in a quasi-monolithic component and relies on cube beamsplitters and beam transmission through perpendicular surfaces to keep angular alignment constant when operating in air or in a vacuum, which leads to the generation of ghost beams that can limit the phase readout linearity. We investigated the coupling of these beams into the non-linear phase readout scheme of DFMI and implemented adjustments of the phase estimation algorithm to reduce this effect. This was done through a combination of balanced detection and the inherent orthogonality of beat signals with different relative time-delays in deep frequency modulation interferometry, which is a unique feature not available for heterodyne, quadrature or homodyne interferometry.
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Martínez-Tapia, Áulide, Samuel Corona-Aquino, Freiman Triana-Arango, Chenglong You, Rui-Bo Jin, Omar S. Magaña-Loaiza, Shi-Hai Dong, Alfred B. U’Ren e Roberto de J. León-Montiel. "Witnessing entangled two-photon absorption via quantum interferometry". APL Photonics 8, n.º 3 (1 de março de 2023): 036104. http://dx.doi.org/10.1063/5.0128249.
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Recent investigations have suggested that the use of non-classical states of light, such as entangled photon pairs, may open new and exciting avenues in experimental two-photon absorption spectroscopy. Despite several experimental studies of entangled two-photon absorption (eTPA), there is still a heated debate on whether eTPA has truly been observed. This interesting debate has arisen mainly because it has recently been argued that single-photon-loss mechanisms, such as scattering or hot-band absorption, may mimic the expected entangled-photon linear absorption behavior. In this work, we focus on transmission measurements of eTPA and explore three different two-photon quantum interferometers in the context of assessing eTPA. We demonstrate that the so-called N00N-state configuration is the only one among those considered insensitive to linear (single-photon) losses. Remarkably, our results show that N00N states may become a potentially powerful tool for quantum spectroscopy, placing them as a strong candidate for the certification of eTPA in an arbitrary sample.
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Zou, Lilong, Weike Feng, Olimpia Masci, Giovanni Nico, Amir M. Alani e Motoyuki Sato. "Bridge Monitoring Strategies for Sustainable Development with Microwave Radar Interferometry". Sustainability 16, n.º 7 (22 de março de 2024): 2607. http://dx.doi.org/10.3390/su16072607.
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The potential of a coherent microwave radar for infrastructure health monitoring has been investigated over the past decade. Microwave radar measuring based on interferometry processing is a non-invasive technique that can measure the line-of-sight (LOS) displacements of large infrastructure with sub-millimeter precision and provide the corresponding frequency spectrum. It has the capability to estimate infrastructure vibration simultaneously and remotely with high accuracy and repeatability, which serves the long-term serviceability of bridge structures within the context of the long-term sustainability of civil engineering infrastructure management. In this paper, we present three types of microwave radar systems employed to monitor the displacement of bridges in Japan and Italy. A technique that fuses polarimetric analysis and the interferometry technique for bridge monitoring is proposed. Monitoring results achieved with full polarimetric real aperture radar (RAR), step-frequency continuous-wave (SFCW)-based linear synthetic aperture, and multi-input multi-output (MIMO) array sensors are also presented. The results reveal bridge dynamic responses under different loading conditions, including wind, vehicular traffic, and passing trains, and show that microwave sensor interferometry can be utilized to monitor the dynamics of bridge structures with unprecedented spatial and temporal resolution. This paper demonstrates that microwave sensor interferometry with efficient, cost-effective, and non-destructive properties is a serious contender to employment as a sustainable infrastructure monitoring technology serving the sustainable development agenda.
Teses / dissertações sobre o assunto "Non-linear interferometry"
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Galetti, Erica. "Seismic interferometry and non-linear tomography". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10506.
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Seismic records contain information that allows geoscientists to make inferences about the structure and properties of the Earth’s interior. Traditionally, seismic imaging and tomography methods require wavefields to be generated and recorded by identifiable sources and receivers, and use these directly-recorded signals to create models of the Earth’s subsurface. However, in recent years the method of seismic interferometry has revolutionised earthquake seismology by allowing unrecorded signals between pairs of receivers, pairs of sources, and source-receiver pairs to be constructed as Green’s functions using either cross-correlation, convolution or deconvolution of wavefields. In all of these formulations, seismic energy is recorded and emitted by surrounding boundaries of receivers and sources, which need not be active and impulsive but may even constitute continuous, naturally-occurring seismic ambient noise. In the first part of this thesis, I provide a comprehensive overview of seismic interferometry, its background theory, and examples of its application. I then test the theory and evaluate the effects of approximations that are commonly made when the interferometric formulae are applied to real datasets. Since errors resulting from some approximations can be subtle, these tests must be performed using almost error-free synthetic data produced with an exact waveform modelling method. To make such tests challenging the method and associated code must be applicable to multiply-scattering media. I developed such a modelling code specifically for interferometric tests and applications. Since virtually no errors are introduced into the results from modelling, any difference between the true and interferometric waveforms can safely be attributed to specific origins in interferometric theory. I show that this is not possible when using other, previously available methods: for example, the errors introduced into waveforms synthesised by finite-difference methods due to the modelling method itself, are larger than the errors incurred due to some (still significant) interferometric approximations; hence that modelling method can not be used to test these commonly-applied approximations. I then discuss the ability of interferometry to redatum seismic energy in both space and time, allowing virtual seismograms to be constructed at new locations where receivers may not have been present at the time of occurrence of the associated seismic source. I present the first successful application of this method to real datasets at multiple length scales. Although the results are restricted to limited bandwidths, this study demonstrates that the technique is a powerful tool in seismologists’ arsenal, paving the way for a new type of ‘retrospective’ seismology where sensors may be installed at any desired location at any time, and recordings of seismic events occurring at any other time can be constructed retrospectively – even long after their energy has dissipated. Within crustal seismology, a very common application of seismic interferometry is ambient-noise tomography (ANT). ANT is an Earth imaging method which makes use of inter-station Green’s functions constructed from cross-correlation of seismic ambient noise records. It is particularly useful in seismically quiescent areas where traditional tomography methods that rely on local earthquake sources would fail to produce interpretable results due to the lack of available data. Once constructed, interferometric Green’s functions can be analysed using standard waveform analysis techniques, and inverted for subsurface structure using more or less traditional imaging methods. In the second part of this thesis, I discuss the development and implementation of a fully non-linear inversion method which I use to perform Love-wave ANT across the British Isles. Full non-linearity is achieved by allowing both raypaths and model parametrisation to vary freely during inversion in Bayesian, Markov chain Monte Carlo tomography, the first time that this has been attempted. Since the inversion produces not only one, but a large ensemble of models, all of which fit the data to within the noise level, statistical moments of different order such as the mean or average model, or the standard deviation of seismic velocity structures across the ensemble, may be calculated: while the ensemble average map provides a smooth representation of the velocity field, a measure of model uncertainty can be obtained from the standard deviation map. In a number of real-data and synthetic examples, I show that the combination of variable raypaths and model parametrisation is key to the emergence of previously-unobserved, loop-like uncertainty topologies in the standard deviation maps. These uncertainty loops surround low- or high-velocity anomalies. They indicate that, while the velocity of each anomaly may be fairly well reconstructed, its exact location and size tend to remain uncertain; loops parametrise this location uncertainty, and hence constitute a fully non-linearised, Bayesian measure of spatial resolution. The uncertainty in anomaly location is shown to be due mainly to the location of the raypaths that were used to constrain the anomaly also only being known approximately. The emergence of loops is therefore related to the variation in raypaths with velocity structure, and hence to 2nd and higher order wave-physics. Thus, loops can only be observed using non-linear inversion methods such as the one described herein, explaining why these topologies have never been observed previously. I then present the results of fully non-linearised Love-wave group-velocity tomography of the British Isles in different frequency bands. At all of the analysed periods, the group-velocity maps show a good correlation with known geology of the region, and also robustly detect novel features. The shear-velocity structure with depth across the Irish Sea sedimentary basin is then investigated by inverting the Love-wave group-velocity maps, again fully non-linearly using Markov chain Monte Carlo inversion, showing an approximate depth to basement of 5 km. Finally, I discuss the advantages and current limitations of the fully non-linear tomography method implemented in this project, and provide guidelines and suggestions for its improvement.
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Romare, Dario. "The application of adaptive linear and non-linear filters to fringe order identification in white-light interferometry systems". Thesis, City, University of London, 1998. http://openaccess.city.ac.uk/19993/.
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Conventional optical interferometry systems driven by highly coherent light sources have a very short unambiguous operating range, a direct consequence of the flatness of the interference fringes visibility profile at the output of the system. The range can be extended by using a white-light interferometer (WU), which is driven by a low-coherence source and produces a Gaussian visibility profile with a unique maximum in correspondence of the central fringe. Due to system and/or measurement noise, however, the position of the maximum (from which an accurate measurement of the measurand - displacement, temperature, pressure, flow, etc. - can be derived) is not easily detectable, and can lead to large measurement errors. This is especially true in a multiplexing scheme, where the source power is distributed evenly among various sensors, with a corresponding drop in the overall signal-to-noise ratio. The inclusion of a signal processing scheme at the receiver end is thus a necessity. As the fringe pattern at the output of a WLI system is basically a noisy sine wave amplitude modulated by a Gaussian envelope, it can be classified as a non-stationary, narrow-band, linear but non-Gaussian signa\. So far, no attempt has been made to apply digital filtering techniques, as understood in the signal processing community, to the output signal of a WLI system. This thesis constitutes a first step in that direction. Since the only measurable information given by the system is contained in the output signal, the system is modelled as a "black box" driven by the system and measurement noise processes and containing an unknown set of parameters. Standard least squares techniques can then be applied to estimate the parameters of the model, as is usually done in the field of system identification when only noisy output measurements are available. It is shown that identification of the model parameters is equivalent to finding a set of coefficients for an inverse filter which takes the WU signal at its input and delivers the unknown noise process at the output. The non-stationarity of the signal is accounted for by allowing for time variations of the model parameters; this justifies the use of adaptive filters with time-varying coefficients. A new central fringe identification scheme is proposed, based on a modification of the standard least mean square (LMS) adaptive filtering algorithm in combination with amplitude thresholding of the fringe pattern. The new scheme is shown to offer considerable improvement in the identification rate when tested against current schemes over comparable operating ranges, while retaining the computational simplicity and operational speed of the standard LMS. Its performance is also shown to be largely independent of the step-size parameter controlling the rate of convergence and tracking in the standard LMS, which is known to be the main obstacle for a successful application of the algorithm in a practical setting. The non-Gaussianity of the signal is explored and an attempt is made to apply higher-order statistics (HOS) algorithms to central fringe identification. The effectiveness of Gaussianity tests on pilot Gaussian data is seen to depend not only on the number and length of records available but, perhaps more importantly, on the bandwidth of the process. Violation of the stationarity assumption is shown to lead to mis-classification of a seemingly non-Gaussian signal into a Gaussian one, as the visibility profile may alter the distribution of the underlying sinusoid making it appear Gaussian, even when beam diffraction and wavefront aberrations combine to produce a nonGaussian profile. HOS-based adaptive algorithms may still be of some benefit, however, if processing is confined to that region of the fringe pattern where sufficient non-Gaussianity is allowed to develop. Non-linear adaptive filters based on the Volterra theories are finally applied to compensate for possible non-linearities introduced by mismatches in optical components, chromatic aberrations, and analogue-to-digital converters. It is shown that although a Volterra filter is able to reproduce the low-amplitude distortions of the fringe pattern better than a linear filter does, the identification rate does not improve. Reasons are given for such behaviour.
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Yoshino, Hirokazu. "Non-linear model fitting for the measurement of thin films and surface topography". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/25482.
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Inspection of optical components is essential to assure the quality and performance of optical systems. Evaluation of optical components includes metrology measurements of surface topography. It also requires optical measurements including refractive index, thin film thickness, reflectivity and transmission. The dispersion characteristics of optical constants including refractive index are also required. Hence, various instruments are used to make these measurements in research laboratories and for quality assurance. Clearly, it would be a significant advantage and cost saving if a technique was developed that could combine surface metrology with optical measurements. {Coherence Scanning Interferometry} (CSI) (also referred to as {Scanning White Light Interferometry} (SWLI)) has been used widely to measure surface topography with sub-nanometre vertical resolution. One of the benefits of the CSI is that the technique is non-contacting and hence non-destructive. Thus the test surfaces are not affected by the measurement using a CSI instrument whereas damage to the surfaces can occur when using traditional contact methods such as stylus profilometry. However use of CSI is geometrically limited to small areas ($\lesssim 10 \times 10$ mm) with gentle slopes ($\lesssim \ang{40}$) because of the numerical aperture of objective lens whereas stylus profilometry works well with larger areas and higher slopes due to the range of motion of the gauge and the traverse unit. Since the CSI technique is optical and involves light reflection and interference it is possible to extend the technique for the measurement of the thickness of transparent films, the roughness of surfaces buried beneath thin films or interfacial surfaces. It may also be used to determine spectral complex refractive index. This thesis provides an analytical framework of new methods to obtain complex refractive index in a visible light domain and interfacial surface roughness (ISR). It also provides experimental verification of these new capabilities using actual thin film model systems. The original Helical Complex Field (HCF) function theory is presented followed by its existing extensions that enable determination of complex refractive index and interfacial surface roughness. Further theoretical extensions of the HCF theory are also provided: A novel theory to determine the refractive index of a (semi-)transparent film is developed to address the constraint of the current HCF theory that restricted its use to opaque materials; Another novel theory is provided to measure ISR with noise compensation, which avoids erroneous surface roughness caused by the numerical optimisation affected by the existence of noise. The effectiveness of the ISR measurement with noise compensation has been verified using a number of computer simulations. Stylus profilometry is a well established method to provide a profile and has been used extensively as a 'reference' for other techniques. It normally provides a profile on which the roughness and the waviness are computed. Extension of the stylus profilometry technique to areal measurement of asymmetrical surfaces, namely raster scan measurement, requires a system to include error compensation between each traverse. The system errors and the random errors need to be separately understood particular when the measurement of a surface with nanometre-order accuracy is required. In this thesis a mathematical model to locate a stylus tip considering five mechanical errors occurring in a common raster scan profilometer is provided. Based on the model, the simulator which provides an areal measurement of a sphere was developed. The simulator clarified the relationship between the Zernike coefficients obtained from the form residual and the size of the errors in the form of partial derivatives of Zernike coefficients with respect to the errors. This provides theoretical support to the empirical knowledge of the relationship between the coefficients and the errors. Furthermore, a method to determine the size of errors directly from Zernike coefficients is proposed supported by simulations. Some of the error parameters were accurately determined avoiding iterative computation with this method whereas the errors are currently being determined by iterative computation.
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Duro, Javier. "Development of new methodologies for the detection, measurement and on going monitoring of ground deformation using spaceborne SAR data". Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00638089.
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Persistent Scatterer Interferometric techniques are very powerful geodetic tools for land deformation monitoring that offer the typical advantages of the satellite remote sensing SAR (Synthetic Aperture Radar) systems : a wide coverage at a relatively high resolution. Those techniques are based on the analysis of a set of SAR images acquired over a given area. They overcome the decorrelation problem by identifying elements (in resolution cells) with a high quality returned SAR signal which remains stable in a series of interferograms. These techniques have been useful for the analysis of urban areas, where man-made objects produce good reflections that dominate over the background scattering, as well as in field areas where the density of infrastructures is more limited. Typically, PSI technique requires an approximate a priori temporal model for the detection of the deformation, even though characterizing the temporal evolution of a deformation is commonly one of the objectives of any study.This work is focused on a particular PSI technique, which is named Stable Point Network (SPN) and that it has been completely developed by Altamira Information in 2003. The work concisely outlines the main characteristics of this technique, and describes its main products: average deformation maps, deformation time series of the measured points, and the so-called maps of the residual topographic error, which are used to precisely geocode the PSI products. The main objectives of this PhD are the identification and analysis of the drawbacks of this processing chain, and the development of new tools and methodologies in order to overcome them. First, the performances of the SPN technique are examined and illustrated by means of practical cases (based on real test sites made with data coming from different sensors) and simulated scenarios.Thus, the main drawbacks of the technique are identified and discussed, such as the lack of automatic quality control parameters, the evaluation of the input data quality, the selection of good points for the measurements and the use of a functional model to unwrap the phases based on a linear deformation trend in time. Then, different enhancements are proposed. In particular, the automatic quality control of the coregistration procedure has been introduced through the analysis of the inter-pixel position of some natural point targets-like pixels identified within the images. The enhancements in the selection of the final points of measurements (the final PSI map) come by means of the analysis of the SAR signal signature of the strong targets presented within the image, in order to select only the center of the main lobe as point of measurement. The introduction of robustness within some critical steps of the technique is done by means of the analysis of the rotational of the estimates in close loops within a network of relative measurements, and by means of the implementation of a different integration methodology, which can be ran in parallel in order to compare it with the classical one. Finally, the main drawback of the technique, the use of a linear model for the detection of ground deformations, is addressed with the development of a new fitting methodology which allows possible change of trends within the analyzed time span. All those enhancements are evaluated with the use of real examples of applications and with simulated data. In particular, the new methodology for detecting non-linear ground deformations has been tested in the city of Paris, where a large stacking of ERS1/2 and ENVISAT SAR images are available. Those images are covering a very large time period of analysis at where some known non-linear ground deformations where occurring
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Tephany, Christophe. "Analyse de la formabilité de renforts composites à base de fibres naturelles". Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2051/document.
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Cette thèse s’intéresse à la déformabilité des renforts à bases de fibres de lin lors de leur mise en forme, au cours du procédé RTM (Resin Tranfer Molding), notamment lorsque les formes considérées sont complexes. La compréhension des défauts et mécanismes de déformations de ces renforts est alors nécessaire. S’appuyant sur un banc d’essai d’emboutissage spécifique, une caractérisation globale (défauts de mise en forme) et locale (déformations des mèches par méthode optique) des préformes a été réalisée, pour différents paramètres procédés (pressions serre-flan et orientation du renfort) et matériaux (architecture). De cette étude, un défaut spécifique lors de la mise en forme a été mis en évidence : le bouclage, sous la forme de flambement hors plan des mèches. Afin de contribuer à sa compréhension, peu décrite dans la littérature, un banc de caractérisation, indépendamment du procédé, a été conçu pour reproduire le phénomène dans le plan et identifier les différents mécanismes à l’origine de ce défaut. Une méthode interférométrique pour quantifier ce phénomène est proposée et une étude paramétrique est réalisée (tensions appliquées, angle de courbure, orientation, architecture du renfort). Au sein du renfort, le comportement des mèches présente de fortes non-linéarités en tension. Un modèle macroscopique par éléments finis est proposé afin de mettre en avant l’importance de ces non-linéarités sur les résultats numérique issus de l’opération de formage. Une étude de sensibilité sous différentes conditions procédés de ces non-linéarités est également apportéeThis study concerns the manufacturing process of composite material from woven flax reinforcement and specifically the preforming stage of the RTM (Resin Transfer Molding) process, with complex geometries. During the process several deformation modes take place and several defects may appear and it is therefore important to understand the mechanisms controlling their appearance. A specific sheet forming bench has been used to characterise the formed shapes at the macroscopic scale (global defects) as well as at the mesoscopic scale (tow strains). Various process parameters (blank holder pressures and reinforcement orientation) and the local tensile strains were measured using an optical method. From the observed defects, the tow buckling, out of plane bending of tows, was particularly investigated as this one is not very much described in the litterature. An experimental setup independent of the forming process was designed to specifically study this defect and to quantify the key parameters controlling its appearance. An interferometric method was proposed to measure the size of the buckles with accuracy and a parametric study (applied tensions, bending angles, orientation and architecture of the reinforcement) has been completed. Within the reinforcement, the tensile behaviour of tows presents strong non-linearities. A finite elements model at the macroscopic scale is proposed to highlight the impact of these non-linearities on the forming modeling results. A sensitivity study under several process conditions has been realized
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Matha, Robin. "Interférométrie self-mixing pour la détection des conditions givrantes". Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5018.
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Nous proposons ici une méthode permettant d'effectuer la détection de gouttelettes d'eau en condition atmosphérique de façon fiable et robuste. Pour cela, nous avons choisi de tester l'application de l'interférométrie self-mixing à cette problématique. Cette technique optique complexe consiste à extraire une information d'un signal d'interférométrie non-linéaire obtenu aux bornes d'une diode laser soumise à une rétro-injection optique sur une scène. C'est cette scène qui génère et contient l'information. Le cas d'étude représentatif est celui d'une surface solide en déplacement longitudinal dans l'axe du faisceau laser ; le signal se compose de franges d'interférométrie qui se forment dans le milieu non-linéaire qu'est le laser, chaque frange correspond à un déplacement de λ/2 de la surface (λ étant la longueur d'onde du laser) et l'orientation donne le sens du déplacement de cette surface. L'interféromètre self-mixing, une simple diode laser équipée d'une alimentation et d'une amplification en sortie, est connue pour offrir une grande versatilité dans la nature des mesures faisables (mesure de vitesse, détection de micro particules, imagerie 3D, etc) mais il offre également des avantages importants dans la conception d'un capteur : compacité, éléments robustes, peu consommateur en énergie, système auto-aligné et intrinsèquement simple. Cependant, la disponibilité de la mesure dans le signal est très dépendante de la quantité de lumière réinjectée dans la cavité laser. Dans le cadre d'une surface rugueuse cela se traduit par le renouvellement de la figure de speckle générée par la réflexion du faisceau laser sur cette surface. Nous démontrons que la disponibilité de la mesure peut être assurée en extrayant l'information depuis trois canaux d'interférométrie self-mixing (alimentation, système optique et amplification du signal) indépendants mais également en traitant ces signaux à l'aide d'un réseau de neurones pré-entrainé dans ce cadre représentatif de la surface en déplacement. Ainsi, tant qu'au moins un canal présente une information disponible le réseau neuronal est capable de reconstruire la vitesse de déplacement de la surface avec précision. De plus, l'analyse parallèle de plusieurs canaux permet d'augmenter la précision de cette reconstruction. Après avoir effectué ces travaux d'augmentation de la robustesse de l'obtention d'une mesure, ceux-ci ont été adapté à la détection de gouttes d'eau micrométriques. Après avoir adapté le réseau de neurone pour classifier les signaux ; nous parvenons à détecter avec un très faible taux d'erreur la présence de gouttelettes devant le faisceau. De plus, nous sommes également parvenus à classifier des signaux d'interférométrie issus de trois scènes différentes : un nuage de gouttes d'eau micrométriques et le même nuage dans lequel sont injectées de plus grosses gouttelettes dont le diamètre est supérieur à 100 µm avec deux distributions de tailles différentes. Finalement, nous sommes parvenus à allier intelligence artificielle avec un phénomène optique complexe pour faire la démonstration de principe d'un capteur simple, robuste, compact et fiable capable de détecter la présence de gouttelettes dans l'atmosphère ainsi que de distinguer des variations de taille de ces gouttelettes composant le nuageHere we propose a method allowing the detection of water droplets in atmospheric conditions in a reliable and robust manner. For this, we chose to test the application of self-mixing interferometry to this problem. This complex optical technique consists of extracting information from a non-linear interferometry signal obtained at the terminals of a laser diode subjected to optical feedback onto a scene. It is this scene that generates and contains the information. The representative case study is that of a solid surface moving longitudinally in the axis of the laser beam; the signal is composed of interferometry fringes which form in the non-linear medium which is the laser, each fringe corresponds to a displacement of λ/2 of the surface (λ being the wavelength of the laser) and l The orientation gives the direction of movement of this surface. The self-mixing interferometer, a simple laser diode equipped with a power supply and output amplification, is known to offer great versatility in the nature of the measurements possible (speed measurement, detection of micro particles, 3D imaging, etc) but it also offers important advantages in the design of a sensor: compactness, robust elements, low energy consumption, self-aligned and intrinsically simple system. However, the availability of the measurement in the signal is very dependent on the quantity of light reinjected into the laser cavity. In the context of a rough surface this results in the renewal of the speckle pattern generated by the reflection of the laser beam on this surface.We demonstrate that the availability of the measurement can be ensured by extracting information from three independent self-mixing interferometry channels (power supply, optical system and signal amplification) but also by processing these signals using a network of neurons pre-trained in this framework representative of the moving surface. Thus, as long as at least one channel presents available information, the neural network is able to reconstruct the speed of movement of the surface with precision. In addition, the parallel analysis of several channels makes it possible to increase the precision of this reconstruction. After carrying out this work to increase the robustness of obtaining a measurement, they were adapted to the detection of micrometric water drops. After adapting the neural network to classify the signals; we manage to detect the presence of droplets in front of the beam with a very low error rate. In addition, we also managed to classify interferometry signals from three different scenes: a cloud of micrometric water drops and the same cloud into which larger droplets with a diameter greater than 100 µm are injected with two distributions of different sizes. Finally, we managed to combine artificial intelligence with a complex optical phenomenon to demonstrate in principle a simple, robust, compact and reliable sensor capable of detecting the presence of droplets in the atmosphere as well as distinguishing variations in size of these droplets making up the cloud
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Boardman, Steven Robert. "High resolution infrared spectroscopy using non-linear mixing and interferometric techniques". Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358609.
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Cassagne, Christophe. "Développement des procédés de mesure de déphasage optique : applications aux non linéarités induites par effet Kerr dans certaines molécules organiques". Thesis, Angers, 2018. http://www.theses.fr/2018ANGE0010/document.
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Notre étude concerne la mesure du déphasage optique non linéaire (NL) d’ordre trois. Deux catégories de procédés seront abordées : i) la technique interférométrique à décalage de phase qui permet la caractérisation de la phase avec une bonne résolution spatiale, ce qui est crucial pour un faisceau focalisé dans le milieu non linéaire. Cette technique utilise le critère des moindres carrés associé à plusieurs interférogrammes. Mise en œuvre à l'aide d'un modulateur spatial de lumière, elle fournit un calibrage pratique pour chaque déphasage considéré. La fiabilité de la méthode proposée est vérifiée par comparaison directe avec la méthode de transformation de Fourier ; ii) les méthodes innovantes de type Z-scan combinées avec un montage imageur. Elles seront ici appliquées aux mesures des coefficients NL d’ordre trois et d’ordres supérieurs. Nous montrerons que la flexibilité d’emploi d'une caméra CCD permet un meilleur pointage et suivi en temps réel du faisceau. Enfin nous nous intéresserons au montage Dark-field Z-scan bénéficiant des avantages de la microscopie à champ sombre à fort contraste. Ces améliorations ouvrent potentiellement un nouveau champ d’exploration microscopique pour l’investigation et la cartographie des effets non linéairesOur study concerns the measurement of the nonlinear (NL) optical phase shift of order three. Two categories of methods will be addressed: i) the phaseshift interferometric technique that allows phase characterization with good spatial resolution, which is crucial for a focused beam in the non-linear medium. This technique uses the least squares criterion associated with several interferograms. Implemented using a spatial light modulator, it provides a practical calibration for each phase shift considered. The reliability of the proposed method is verified by direct comparison with the Fourier transformation method; ii) innovative Z-scan methods combined with an imager assembly. They will be applied here to measurements of the NL coefficients of order three and higher. We will show that the flexibility of using a CCD camera allows for better pointing and real-time tracking of the beam. Finally, we will focus on the Dark-field Z-scan setup, which benefits from the advantages of high contrast dark field microscopy. These improvements potentially open up a new field of microscopic exploration for the investigation and mapping of non-linear effects
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Faderl, Ingo. "Étude et réalisation d'un modulateur électro-optique utilisant des polymères non linéaires dans un circuit optique intégré sur silicium". Grenoble INPG, 1994. http://www.theses.fr/1994INPG0102.
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La these demontre la faisabilite d'un modulateur electro-optique avec des polymeres non lineaires en optique integree sur silicium. Le modulateur est base sur un interferometre de mach-zehnder. L'originalite de ce travail repose sur l'hybridation d'un polymere non-lineaire sur un circuit optique integre passif. Seuls les guides actifs sont fabriques avec des polymeres non-lineaires. Le reste du modulateur est fabrique a l'aide de nitrure de silicium et de silice. Le premier chapitre rappelle les principes de l'optique non-lineaire avec les polymeres. La birefringence, l'absorption, le decalage du spectre d'absorption et le coefficient electro-optique ont ete exprimes en fonction de l'orientation des chromophores. Le deuxieme chapitre traite d'optique guidee dans les materiaux non lineaires. Des simulations ont ete entreprises dans le but de definir la structure guidante presentant le meilleur compromis entre l'utilisation optimale de la non-linearite et le minimum de perte lors du guidage optique. Ensuite, les principes de la fabrication du modulateur sont expliques. La compatibilite physico-chimique des polymeres avec la photo-lithographie et la gravure ionique reactive est un point important. La gravure ionique reactive est decrite en detail pour les polysiloxanes et le pmma. Finalement, le modulateur a ete caracterise en terme de pertes de propagation et de couplage, de coefficient electro-optique, de bande passante et de taux d'extinction
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Groß, Christian [Verfasser]. "Spin squeezing and non-linear atom interferometry with Bose-Einstein condensates / Christian Groß". 2010. http://d-nb.info/1002649919/34.
Texto completo da fonteLivros sobre o assunto "Non-linear interferometry"
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Groß, Christan. Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25637-0.
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service), SpringerLink (Online, ed. Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012.
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Groß, Christian. Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates. Springer, 2014.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Non-linear interferometry"
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Groß, Christian. "Non-linear Interferometry Beyond the Standard Quantum Limit". In Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates, 59–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25637-0_4.
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Groß, Christian. "Introduction". In Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates, 1–4. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25637-0_1.
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Groß, Christian. "Spin Squeezing, Entanglement and Quantum Metrology". In Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates, 5–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25637-0_2.
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Groß, Christian. "Squeezing Two Mean Field Modes of a Bose–Einstein Condensate". In Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates, 25–58. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25637-0_3.
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Groß, Christian. "Outlook". In Spin Squeezing and Non-linear Atom Interferometry with Bose-Einstein Condensates, 93–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25637-0_5.
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Sousa, Fabio Barros de, Fiterlinge Martins de Sousa, Jorge Everaldo de Oliveira, Elizabeth Rego Sabino e Marcos Benedito Caldas Costa. "DATA REGENERATION 2R IN OPTICAL COMMUNICATION NETWORK BASED ON MACHZEHNDER INTERFEROMETER WITH ACOUSTICOPTICAL FILTER AND HIGHLY NON-LINEAR PHOTONIC CRYSTAL FIBER". In Engenharia Elétrica e de Computação: Atividades Relacionadas com o Setor Científico e Tecnológico, 81–94. Atena Editora, 2020. http://dx.doi.org/10.22533/at.ed.6712002077.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Non-linear interferometry"
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Wolterink, Tom A. W., Matthias Heinrich, Stefan Scheel e Alexander Szameit. "Order-Invariant Quantum Correlations in non-Hermitian Interferometers". In Quantum 2.0, QTu3A.15. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/quantum.2024.qtu3a.15.
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We identify sequences of concatenated two-mode systems that perform distinct linear optical transformations, whereas their two-photon behavior is invariant under reversal of the order. We experimentally verify this behavior in non-Hermitian interferometers of varying composition.
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Monteil, Andre, Georges Boudebs, Franois Sanchez, Claire Duverger, Brigitte Boulard, Johann Troles e Frederic Smektala. "Non linear refractive indices measurements by interferometry techniques". In 19th Congress of the International Commission for Optics: Optics for the Quality of Life, editado por Giancarlo C. Righini e Anna Consortini. SPIE, 2003. http://dx.doi.org/10.1117/12.525513.
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Wapenaar, Kees. "Seismic interferometry, the optical theorem and a non‐linear point diffractor". In SEG Technical Program Expanded Abstracts 2009. Society of Exploration Geophysicists, 2009. http://dx.doi.org/10.1190/1.3255612.
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Massinas, Basil, Nikolaos Doulamis e Demitris Paradissis. "Adaptive Non-Linear Modeling for Ionospheric Disturbances Behavior Estimation on Spaceborne Synthetic Aperture Radar Interferometry". In AIAA SPACE 2012 Conference & Exposition. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-5180.
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Ibrahim, Heide, Craig Chapman, Hiroyuki Katsuki, Jeffrey Cina e Kenji Ohmori. "Wave Packet Reconstruction on Unknown Potential Surfaces by Two-Colour Non-Linear Wave Packet Interferometry". In International Conference on Ultrafast Phenomena. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/up.2010.wb2.
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Zhou, 周勇, e Tong Guo. "Non-linear phase noise processing method in thin film measurement with the frequency domain white light microscopic interferometry". In LIDAR Imaging Detection and Target Recognition 2017, editado por Yueguang Lv, Jianzhong Su, Wei Gong, Jian Yang, Weimin Bao, Weibiao Chen, Zelin Shi, Jindong Fei, Shensheng Han e Weiqi Jin. SPIE, 2017. http://dx.doi.org/10.1117/12.2296315.
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Singh, Sandeep, Vimlesh Kumar, Varun Sharma, Daniele Faccio e G. K. Samanta. "Hong-Ou-Mandel interferometry for high precision sensing of real-time vibrations". In Frontiers in Optics. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/fio.2023.jtu5a.58.
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We demonstrate the real-time sensing of high frequency vibrations with sub-micron amplitudes using the Hong-Ou-Mandel interferometer of narrow dip width resulted from the broadband parametric down-converted photons generated in non-linear crystals of short interaction length.
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Song, Ningfang, Xinkai Luo, Huipeng Li e Jiao Li. "Overall non-linear correction of phase shifting mechanism in white light interferometry system based on displacement feedback control combined with fuzzy PID control". In Applied Optics and Photonics China (AOPC2015), editado por Sen Han, Jonathan D. Ellis, Junpeng Guo e Yongcai Guo. SPIE, 2015. http://dx.doi.org/10.1117/12.2199693.
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Zou, Daqing, Jianjun Wang, Minfu Lu e Sheng Liu. "Creep Behavior Study of Plastic Power Package by Real Time Moiré Interferometry and FEM Modeling". In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1227.
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Abstract In this paper, the creep behavior of the plastic power package at high temperature 155 °C was studied by real time moiré interferometry and FEM modeling. 1200 l/mm grating was replicated onto the cross-section of the specimen at room temperature. The specimen was held at 155°C (around the Tg of the epoxy molding compound) in the vacuum chamber for about 13 hours. The thermal deformation and creep of the specimen was recorded and measured in situ by moiré interferometry. The experimental results show that creep deformation occurs in the epoxy molding compound. The non-linear viscoelastic constitutive model was used for FEM simulation. The simulation results were compared with the experimental results and they were matched quite well on the global deformation of the specimen. The calculation results also show that, accompanied with the global creep deformation in molding compound epoxy, local stress concentration decreased significantly.
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Fedorov, S. V., G. V. Khodova, K. S. Kostritskaya e N. N. Rosanov. "New Types of Switching Waves and Diffractive Autosolitons in Wide-Aperture Nonlinear Interferometers and Lasers". In Nonlinear Dynamics in Optical Systems. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/nldos.1992.tuc20.
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We investigate the new types of transverse patterns in wide-aperture passive interferometers and lasers. We propose and analyze equations of motion for a diffractive autosoliton in passive nonlinear interferometers excited by external coherent radiation with gradually non-uniform characteristics. If external radiation wave front does not contain dislocations at the interferometer aperture, autosoliton moves along the steepest descent lines of effective potential expressed by linear combination of the intensity and the phase of radiation incident on the interferometer. With the dislocations, the motion with autosoliton rotation becomes possible. The coupled switching wave and autosoliton structures in bistable and multistable interferometers are studied. The dynamics of autosoliton formation in conditions of transverse field structure instability and in nonlinear interferometer with unstable resonator is considered. The peculiarity of autosolitons in lasers with saturated absorption is a diffractive shift of generation frequency. This aspect being taken into account, positive (bright) and negative (dark) laser autosolitons are demonstrated and autosolitons interaction is investigated.