Measuring atomic displacement inside crystals has been an important field of interest for decades especially in semiconductor industry for its effect on the crystal structure and symmetry, subsequently on the bandgap structure. There are three different image based, diffraction based, and electron holography based techniques using transmission electron microscope (TEM). These methods enable measuring atomic displacement inside specimen. However, among all TEM techniques offering nano-scale resolution measurements, convergent beam electron diffraction (CBED) patterns show the highest sensitivity to the atomic displacement. Higher order Laue zone (HOLZ) lines split by small variations of lattice constant allowing the atomic displacement measurement through the crystal. However it is a cumbersome measurement and it can only reveal the atomic displacement in two dimensions. Therefore, the atomic displacement information at each depth through the specimen thickness is still missing. This information can be obtained by recovering the phase information across the split HOLZ line. The phase profile across the split HOLZ line can be retrieved by the electron interferometry method. The phase of the diffracted beam is the required information to reconstruct the atomic displacement profile through the specimen thickness. In this work, we first propose a novel technique of self-interference of split HOLZ line based on the diffracted beam interferometry which recovers the phase information across the split HOLZ line. The experimental details of the technique have been examined to report the parameters in order to implement the method. Regarding the novelty of the technique and the lack of the of a reference phase profile to discuss the results, phase profile simulation was a main contribution. For simulating the phase profile across the split HOLZ line the Howie-Whelan formula supporting the kinematical theory of diffraction is used. Accordingly, the analytical approach to simulate the phase profiles across the split HOLZ line for three various suggested atomic displacements are studied. Also, the effect of some parameters such as the atomic displacement amplitude, the specimen thickness, and the g reflection is investigated on the phase profile. This study leads to an equation used for fitting the experimental results with the simulated phase profile. Consequently, self-interference of split HOLZ line (SIS-HOLZ) is studied as a method of reconstructing the phase profile across the split HOLZ line which carries the information of atomic displacement through the specimen thickness. / Graduate / 0548 / 0794 / mananrp@uvic.ca

Los Radares de Apertura Sintética, o sistemas SAR, representan el mejorejemplo de sistemas activos de teledetección por microondas. Debido a su naturaleza coherente, un sistema SAR es capaz de adquirir información dedispersión electromagnética con una alta resolución espacial, pero por otro lado, esta naturaleza coherente provoca también la aparición de speckle.A pesar de que el speckle es una medida electromagnética, sólo puede ser analizada como una componente de ruido debido a la complejidad asociadacon el proceso de dispersión electromagnética.Para eliminar los efectos del ruido speckle adecuadamente, es necesario un modelo de ruido, capaz de identificar las fuentes de ruido y como éstasdegradan la información útil. Mientras que este modelo existe para sistemasSAR unidimensionales, conocido como modelo de ruido speckle multiplicativo,éste no existe en el caso de sistemas SAR multidimensionales.El trabajo presentado en esta tesis presenta la definición y completa validación de nuevos modelos de ruido speckle para sistemas SAR multidimensionales,junto con su aplicación para la reducción de ruido speckle y la extracción de información.En esta tesis, los datos SAR multidimensionales, se consideran bajo una formulación basada en la matriz de covarianza, ya que permite el análisisde datos sobre la base del producto complejo Hermítico de pares de imágenesSAR. Debido a que el mantenimiento de la resolución especial es un aspectoimportante del procesado de imágenes SAR, la reducción de ruido speckleestá basada, en este trabajo, en la teoría de análisis wavelet.

Las técnicas de Interferometría Diferencial se basan en la combinación de varias imágenes SAR con distinta separación temporal y permiten la recuperación de las componentes lineales y no-lineales del proceso de deformación ocurrida en el entorno de interés durante el entero periodo de observación. Condición imprescindible para una correcta estimación de los fenómenos geodéticos es la elevada estabilidad de la plataforma que embarca el sensor SAR. Por esta razón, a nivel operativo se utilizan datos SAR satelitales.El objetivo de la Polarimetría SAR es describir el entorno de interés analizando las propiedades de la señal que éste dispersa cuando se utilizan diferentes combinaciones de polarización de las antenas transmisora y receptora, definidas canales polarimétricos. La polarimetría interferométrica SAR junta la capacidad de la polarimetría de separar mecanismos de dispersión independientes con la sensibilidad de la Interferometría a la altura de los correspondientes centros de fase, y permite describir la distribución volumétrica de los dispersores dentro de la escena observada. Debido a la falta de conjuntos de datos polarimétricos SAR satelitales que cubran tramos temporales suficientemente largos, hay aún un gran interés en las mejoras que la polarimetría podría aportar a técnicas ya consolidadas como las de Interferometría Diferencial.La actividad de investigación que se presentará en esta tesis doctoral abarca, por primera vez conjuntamente, las dos áreas de la Polarimetría SAR y de la Interferometría Diferencial utilizando el sensor radar terrestre de corto alcance (gbSAR) desarrollado por la Universitat Politècnica de Catalunyua (UPC). El trabajo constará de dos bloques principales.El primer bloque describirá las técnicas que se han desarrollado para convertir el sistema UPC gbSAR en un instrumento operativo y simplificar la utilización de sus adquisiciones, incluyendo la formulación matemática de los principios de funcionamiento del sistema, la cadena de procesado de los raw data y su calibración polarimétrica, los procedimientos de georeferenciación, y las técnicas de compensación de los artefactos atmosféricos presentes en sus medidas diferenciales.La segunda parte se ocupará de demostrar los beneficios que los datos SAR polarimétricos ofrecen respecto a la medición de un único canal polarimétrico para aplicaciones diferenciales. A fin de llevar a cabo esta tarea, se analizarán los datos gbSAR adquiridos durante una campaña de medidas de un año realizada en el pueblo de Sallent, en Cataluña, afectado por un fenómeno de subsidencia. En esta parte se analizarán tres temas principales. El primero es el comportamiento no estacionario en tiempo del entorno urbano bajo la geometría de observación del sensor terrestre. Se estudiarán en detalle los efectos de su inestabilidad y se propondrá una técnica de filtrado novedosa entallada a las propiedades de los blancos deterministas con el fin de preservar la información de la fase diferencial. El segundo tema abarca el problema de los efectos de troposfera en datos diferenciales con separación temporal superior al mes y de su separación de las variaciones de fase inducidas por el proceso de deformación. El tercer tema es la utilización de toda la información polarimétrica diferencial. Con fin de superar las limitaciones propias de las técnicas DInSAR clásicas, se propondrá un nuevo modelo polarimétrico de dispersión y se demostrarán las ventajas de la nueva formulación enseñando la mejor estimación del proceso de subsidencia en Sallent. En la parte final de este apartado se explorará también el potencial de las técnicas polarimétricas de optimización de la coherencia para aplicaciones diferenciales. / Differential SAR interferometry (DInSAR) deals with the combination of multi-temporal SAR images for the estimation of the linear and non-linear components of the deformation process within an area of interest during the whole observation period. A high stability of the platform is required for a reliable estimation of the geodetic phenomena. Accordingly, space-borne SAR images are operatively employed for DInSAR estimation, air-borne DInSAR still constituting a challenging research issue. SARPolarimetry aims at charactering the illuminated area through the analysis of its response under different combinations of transmitting and receiving antennas polarization, called polarimetric channels. The Polarimetric SAR Interferometry joins the capability of Polarimetry to separate independent scattering mechanisms and the sensitivity of Interferometry to the corresponding phase centers' elevation, making it possible to describe the volumetric distribution of the scatterers within the observed area. Owing to the lack of long-time collections of polarimetric space-borne SAR data, the studies carried out in this research field have been mainly based on air-borne acquisitions. Yet, there is a great expectation for the improvements that polarimetry may bring to assessed single-polarization techniques such as the DinSAR.The research described in this PhD dissertation fills for the first time the gap between SAR Polarimetry and SAR Differential Interferometry through the employment of an X-band ground-based SAR (gbSAR) sensor developed by the Remote Sensing Lab of the Universitat Politècnica de Catalunya (UPC).The work is divided into two main blocks. The first part deals with the algorithms that have been developed to make the UPC system operative and its acquisitions easy to use. Summarily, they include the mathematical formulation of the sensor's working principles, the raw data processing chain and the polarimetric calibration method, the geocoding procedures, and the techniques compensating for the atmospheric artefacts affecting gbSAR zero-baseline acquisitions.The second part is concerned with demonstrating the benefits that polarimetric SAR measurements provide with respect to single-polarization data for differential applications. In order to cope with this task, the data sets acquired during a one-year measurement campaign carried out in the village of Sallent, northeastern Spain, are analyzed. The experiment was focused on monitoring the subsidence phenomenon affecting a district of the village with the UPC gbSAR sensor. Three main issues are here argued. The first one is the time non-stationary behaviors characterizing the urban environment at X-band in the gbSAR observation geometry. Their effects are analyzed in detail and a novel non-stationary filtering technique tailored to deterministic scatterers' properties is introduced to preserve the differential phase information. The second one is the compensation of the troposphere changes in long-time span gbSAR differential interferograms. A new technique is worked out to effectively separate the differential phase variations due to the atmospheric artefacts from the deformation components. The third one is the use of the whole polarimetric differential information. A novel polarimetric differential scattering model is put forward to relax the constraints of an advanced DInSAR technique, the Coherent Pixel Technique, and to propose an innovative polarimetric approach. The advantages offered by Polarimetric DInSAR are demonstrated in terms of quality of the deformation-rate map describing the subsidence phenomenon in Sallent. In the end, the potentials of coherence-optimization techniques for the further improvement of the deformation process estimation are stressed.

With the dramatic advances that have taken place in microelectronics over the past three decades, ball-grid array (BGA) packages are increasingly being used in microsystems applications. BGA packages with area-array configuration have several advantages: smaller footprint, faster signal transmission, testability, reworkability, handling easiness, etc. Although ceramic ball grid array (CBGA) packages have been used extensively in the microsystems industry, the use of plastic ball grid array (PBGA) packages is relatively new, especially for automotive and aerospace applications where harsh thermal conditions prevail. This thesis work has developed an experimental and a theoretical modeling program to study the reliability of two PBGA packages. The physics-based theoretical models take into consideration the time-dependent creep behavior through power law creep and time-independent plastic behavior through multi-linear kinematic hardening. In addition, unified viscoplastic constitutive models are also taken into consideration. The models employ two damage-metrics, namely inelastic strain and inelastic strain energy density, to predict the solder joint fatigue life. The theoretical predictions have been validated through air-to-air in-house thermal cycling tests carried out between 55 and #61616;C and 125 and #61616;C. In addition, laser-moir interferometry has been used to determine the displacement contours in a cross-section of the package at various temperatures. These contours measured through moir interferometry have also been used to validate the thermally-induced displacement contours, predicted by the models. Excellent agreement is seen between the experimental data and the theoretical predictions. In addition to life prediction, the models have been extended to map the field-use conditions with the accelerated thermal cycling conditions. Both linear and non-linear mapping techniques have been developed employing inelastic strain and strain energy density as the damage metric. It is shown through this research that the symmetric MIL-STD accelerated thermal cycles, currently in practice in industry, have to be modified to account for the higher percentage of creep deformation experienced by the solder joints in the field-use conditions. Design guidelines have been developed for such modifications in the accelerated thermal cycles.

Many essential processes and interactions on atomic and molecular scales occur at ultrafast timescales. The ability to measure and manipulate ultrashort pulses hold the key to probing and understanding these key processes that physicists, engineers, chemists and biologists study today. Measuring ultrashort pulses means that we measure both the intensity (which is a function of time) and the phase of the pulse in time. Or alternately we might measure spectrum and spectral phase (in the corresponding Fourier domain). In the early 1990's, the invention of FROG opened up the field of ultrashort measurement with it's ability to measure the complete pulse. Since then, there have been a whole host of pulse measurement techniques that have been invented to measure all sorts of ultrashort pulses. However, no variation of FROG nor any other fs pulse measurement technique, for that matter, has yet been able to completely measure arbitrary ultraweak femtosecond light pulses such as those found in nature. In this thesis, we will explore a couple of highly sensitive methods in a quest to measure ultraweak ultrashort pulses. We explore the use of Spectral Interferometry, a known sensitive technique as one possibility. We find that it has certain drawbacks that make it not necessarily suitable to tackle this problem. But in the course of our quest, we find that this technique is highly suitable for measuring 10s of picosecond-long shaped pulses. We discuss a couple of developments which make SI highly practical to use for such shaped pulse-measurements. We also develop a new technique which is a variation of FROG, based on the non-linearity of Difference Frequency Generation and Optical Parametric Amplification, which can amplify pulses as weak as a few hundred attojoules to be able to spectrally resolve them and measure the full intensity and phase of these pulses. This technique offers great potential to measure generalized ultraweak ultrashort pulses.

Title from PDF of title page. / Document formatted into pages; contains 87 pages. / Thesis (M.S.M.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: As technology progresses towards smaller electronic packages, thermo-mechanical considerations pose a challenge to package designers. One area of difficulty is the ability to predict the fatigue life of the solder connections. To do this one must be able to accurately model the thermo-mechanical performance of the electronic package. As the solder ball size decreases, it becomes difficult to determine the performance of the package with traditional methods such as the use of strain gages. This is due to the fact that strain gages become limited in size and resolution and lack the ability to measure discreet strain fields as the solder ball size decreases. A solution to the limitations exhibited in strain gages is the use of Moiré interferometry. Moiré interferometry utilizes optical interferometry to measure small, in-plane relative displacements and strains with high sensitivity. / ABSTRACT: Moiré interferometry is a full field technique over the application area, whereas a strain gage gives an average strain for the area encompassed by the gage. This ability to measure full field strains is useful in the analysis of electronic package interconnections; especially when used to measure strains in the solder ball corners, where failure is known to originate. While the improved resolution of the data yielded by the method of Moiré interferometry results in the ability to develop more accurate models, that is not to say the process is simple and without difficulties of it's own. Moiré interferometry is inherently susceptible to error due to experimental and environmental effects; therefore, it is vital to generate a reliable experimental procedure that provides repeatable results. This was achieved in this study by emulating and modifying established procedures to meet our specific application. / ABSTRACT: The developed procedure includes the preparation of the specimen, the replication and transfer of the grids, the use of the PEMI, interpretation of results, and validation of data by finite element analysis using ANSYS software. The data obtained maintained uniformity to the extent required by the scope of this study, and potential sources of error have been identified and should be the subject of further research. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

A new approach to the absolute measurement of two-dimensional optical path differences is presented in this thesis. The method, which incorporates a white light interferometer and a hyperspectral imaging system, is referred to as Hyperspectral Interferometry. A prototype of the Hyperspectral Interferometry (HSI) system has been designed, constructed and tested for two types of measurement: for surface profilometry and for depth-resolved displacement measurement, both of which have been implemented so as to achieve single shot data acquisition. The prototype has been shown to be capable of performing a single-shot 3-D shape measurement of an optically-flat step-height sample, with less than 5% difference from the result obtained by a standard optical (microscope) based method. The HSI prototype has been demonstrated to be able to perform single-shot measurement with an unambiguous 352 (m depth range and a rms measurement error of around 80 nm. The prototype has also been tested to perform measurements on optically rough surfaces. The rms error of these measurements was found to increase to around 4× that of the smooth surface. For the depth-resolved displacement field measurements, an experimental setup was designed and constructed in which a weakly-scattering sample underwent simple compression with a PZT actuator. Depth-resolved displacement fields were reconstructed from pairs of hyperspectral interferograms. However, the experimental results did not show the expected result of linear phase variation with depth. Analysis of several possible causes has been carried out with the most plausible reasons being excessive scattering particle density inside the sample and the possibility of insignificant deformation of the sample due to insufficient physical contact between the transducer and the sample.

This thesis is specialized on composition of workplace for experiments flowing from optical interferometry. Here are described laboratory exercise servant for demonstration basic principles of interferometry. In more details is described method measurement of height profile objects with method white light interferometry.

This thesis deals with a theoretical analysis and experimental verification of a new method for the refractive index of air measurement. This method uses a combination of laser and low-coherence interferometry. The experimental setup is based on the Michelson interferometer equipped with a double-spaced glass cell. The optical path difference between the inner and outer part of the cell that is proportional to air refractivity is estimated using two low-coherence interference signals. These signals are analysed in the frequency domain which results in the dependence of the phase change caused the by air on vacuum wavelength. This dependency is fitted by a theoretical function based on Edlén's equations in order to calculate the phase difference for laser wavelength. This value is then made more accurate utilising two laser interference signals and used for the air refractive index calculation. The new method was experimentally verified and compared to two different techniques. Moreover, the measurement uncertainty was evaluated.

Interferometry and coherent change detection (CCD) utilize phase differences between complex SAR images to find terrain height and to detect small changes between images, respectively. A new method for improving interferometry and CCD using multiple sub-apertures is proposed. Using backprojection processing, multiple sub-aperture images are created for a pair of flights. An interferogram and coherence map is made from each sub-aperture. For CCD, each sub-aperture coherence map offers an independent estimate of the coherence over the same area. By combining coherence maps, low coherence areas associated with residual motion errors are reduced, shadowed areas are minimized, and the overall coherence of stationary objects between images is increased. For interferometry, combining independent estimates of a scene's height offers a more accurate height estimate. For repeat-pass interferometry, multiple apertures are shown to increase the coverage of valid height estimates. The benefits of multi-aperture interferometry and CCD are shown using examples with real data.