Contribution à la modélisation et au développement expérimental de la technique d'acoustique picoseconde pour l'analyse des circuits intégrés

Ce travail présente l'application de la technique d'acoustique picoseconde à l'analyse des circuits intégrés. Le principe est de générer et de détecter des ondes acoustiques de très haute fréquence au moyen d'impulsions laser ultracourtes. Un dispositif expérimental a été conçu, basé sur le principe de l'interféromètre de Sagnac. Un simulateur numérique a été développé afin d'aider à l'interprétation des résultats expérimentaux. Le potentiel de la technique pour la caractérisation et l'analyse non destructive de composants microélectroniques est illustré à travers plusieurs résultats expérimentaux.This work deals with the application of the Picosecond Ultrasonics technique to nondestructive analysis of integrated circuits. This technique is based on generation and detection of very high frequency acoustic waves by means of ultrashort laser pulses. An experimental setup based on the principle of the Sagnac interferometer was designed. A numerical simulation tool was developed in order to contribute to the interpretation of the experimental results. The technique potential for microelectronic devices characterization and non-destructive analysis is illustrated through several experimental results

Tomography applied to Lamb wave contact scanning nondestructive evaluation

The aging world-wide aviation fleet requires methods for accurately predicting the presence of structural flaws that compromise airworthiness in aircraft structures. Nondestructive Evaluation (NDE) provides the means to assess these structures quickly, quantitatively, and noninvasively. Ultrasonic guided waves, Lamb waves, are useful for evaluating the plate and shell structures common in aerospace applications. The amplitude and time-of-flight of Lamb waves depend on the material properties and thickness of a medium, and so they can be used to detect any areas of differing thickness or material properties which indicate flaws. By scanning sending and receiving transducers over an aircraft, large sections can be evaluated after a single pass. However, while this technique enables the detection of areas of structural deterioration, it does not allow for the quantification of the extent of that deterioration. Tomographic reconstruction with Lamb waves allows for the accurate reconstruction of the variation of quantities of interest, such as thickness, throughout the investigated region, and it presents the data as a quantitative map. The location, shape, and extent of any flaw region can then be easily extracted from this Tomographic image. Two Lamb wave tomography techniques using Parallel Projection tomography (PPT) and Cross Borehole tomography (CBT), are shown to accurately reconstruct flaws of interest to the aircraft industry. A comparison of the quality of reconstruction and practicality is then made between these two methods, and their limitations are discussed and shown experimentally. Higher order plate theory is used to derive analytical solutions for the scattering of the lowest order symmetric Lamb wave from a circular inclusion, and these solutions are used to explain the scattering effects seen in the Tomographic reconstructions. Finally, the means by which this scattering theory can be used to develop Lamb wave Tomographic algorithms that are more generally applicable in-the-field, is presented

Development of electronics for microultrasound capsule endoscopy

Development of intracorporeal devices has surged in the last decade due to advancements in the semiconductor industry, energy storage and low-power sensing systems. This work aims to present a thorough systematic overview and exploration of the microultrasound (µUS) capsule endoscopy (CE) field as the development of electronic components will be key to a successful applicable µUSCE device. The research focused on investigating and designing high-voltage (HV, < 36 V) generating and driving circuits as well as a low-noise amplifier (LNA) for battery-powered and volume-limited systems. In implantable applications, HV generation with maximum efficiency is required to improve the operational lifetime whilst reducing the cost of the device. A fully integrated hybrid (H) charge pump (CP) comprising a serial-parallel (SP) stage was designed and manufactured for > 20 V and 0 - 100 µA output capabilities. The results were compared to a Dickson (DKCP) occupying the same chip area; further improvements in the SPCP topology were explored and a new switching scheme for SPCPs was introduced. A second regulated CP version was excogitated and manufactured to use with an integrated µUS pulse generator. The CP was manufactured and tested at different output currents and capacitive loads; its operation with an US pulser was evaluated and a novel self-oscillating CP mechanism to eliminate the need of an auxiliary clock generator with a minimum area overhead was devised. A single-output universal US pulser was designed, manufactured and tested with 1.5 MHz, 3 MHz, and 28 MHz arrays to achieve a means of fully-integrated, low-power transducer driving. The circuit was evaluated for power consumption and pulse generation capabilities with different loads. Pulse-echo measurements were carried out and compared with those from a commercial US research system to characterise and understand the quality of the generated pulse. A second pulser version for a 28 MHz array was derived to allow control of individual elements. The work involved its optimisation methodology and design of a novel HV feedback-based level-shifter. A low-noise amplifier (LNA) was designed for a wide bandwidth µUS array with a centre frequency of 28 MHz. The LNA was based on an energy-efficient inverter architecture. The circuit encompassed a full power-down functionality and was investigated for a self-biased operation to achieve lower chip area. The explored concepts enable realisation of low power and high performance LNAs for µUS frequencies

Engineering derivatives from biological systems for advanced aerospace applications

The present study consisted of a literature survey, a survey of researchers, and a workshop on bionics. These tasks produced an extensive annotated bibliography of bionics research (282 citations), a directory of bionics researchers, and a workshop report on specific bionics research topics applicable to space technology. These deliverables are included as Appendix A, Appendix B, and Section 5.0, respectively. To provide organization to this highly interdisciplinary field and to serve as a guide for interested researchers, we have also prepared a taxonomy or classification of the various subelements of natural engineering systems. Finally, we have synthesized the results of the various components of this study into a discussion of the most promising opportunities for accelerated research, seeking solutions which apply engineering principles from natural systems to advanced aerospace problems. A discussion of opportunities within the areas of materials, structures, sensors, information processing, robotics, autonomous systems, life support systems, and aeronautics is given. Following the conclusions are six discipline summaries that highlight the potential benefits of research in these areas for NASA's space technology programs

Optical techniques for non-destructive detection of flaws in ceramic components

No abstract availableThis thesis primarily concerns development of a non-destructive inspection method for 3mol% Yttria-Stabilised Zirconia Polycrystal (3Y-TZP) ceramics used for dental applications and a scoping study on applying the technique to other ceramic materials applied in thermal barrier coatings and other fields. Zirconia ceramics are materials of great interest for various engineering applications, primarily due to their stiffness, hardness and wear resistance. These factors in combination with the complex manufacturing processes may reduce the material strength and durability due to induced cracking. Knowledge of the extent of this cracking must be obtained and often, if each part is unique as in biomedicine, the assessment must be carried out for every part non-destructively so the part can be subsequently used. Only a few techniques are known for inspection of Zirconia ceramics, however these techniques are not able to detect flaws in thick (above 500 μm) parts. The main limitation for optical inspection of 3Y-TZP is the highly scattering nature of the material due to its multicrystalline grain structure (grains size of 500 nm) which, particularly in the visible region, reduces imaging capabilities. However, a transmission window in the mid-infrared (between 3 and 8 μm) exists opening up the potential for inspection at these wavelengths. Mid-Infrared Transmission Imaging (MIR-TI) and Confocal Mid-Infrared Transmission Imaging (CMIR-TI) techniques were developed for inspection of 3Y-TZP parts which allow for detecting sub mm scale cracks. The measured imaging resolution for the MIR-TI is 42 ± 5 μm, whereas for the CMIR-TI it is below 38.5 ± 5 μm. The maximum sample thickness inspected with the MIR-TI and CMIR-TI is 6 mm and 3.5 mm respectively, considerably more than currently available inspection methods. The MIRTI technique provides fast inspection of the part due to the large field of view (11 by 7 mm), however the high cost and limited imaging resolution make this technique less attractive. The CMIR-TI technique on the other hand is more cost effective due to reduced cost of the infrared sensor and it provides an enhanced imaging capabilities. The promising results achieved with the MIR-TI and CMIR-TI techniques led to the development of reflection equivalents (Camera-MIRI and Confocal-MIRI) for ceramic coating measurements, however further in-depth experiments to determine and quantify the capabilities of both techniques are required

JETC (Japanese Technology Evaluation Center) Panel Report on High Temperature Superconductivity in Japan

The Japanese regard success in R and D in high temperature superconductivity as an important national objective. The results of a detailed evaluation of the current state of Japanese high temperature superconductivity development are provided. The analysis was performed by a panel of technical experts drawn from U.S. industry and academia, and is based on reviews of the relevant literature and visits to Japanese government, academic and industrial laboratories. Detailed appraisals are presented on the following: Basic research; superconducting materials; large scale applications; processing of superconducting materials; superconducting electronics and thin films. In all cases, comparisons are made with the corresponding state-of-the-art in the United States

Microelectromechanical Systems and Devices

The advances of microelectromechanical systems (MEMS) and devices have been instrumental in the demonstration of new devices and applications, and even in the creation of new fields of research and development: bioMEMS, actuators, microfluidic devices, RF and optical MEMS. Experience indicates a need for MEMS book covering these materials as well as the most important process steps in bulk micro-machining and modeling. We are very pleased to present this book that contains 18 chapters, written by the experts in the field of MEMS. These chapters are groups into four broad sections of BioMEMS Devices, MEMS characterization and micromachining, RF and Optical MEMS, and MEMS based Actuators. The book starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices and acoustic biosensors. MEMS characterization, micromachining, macromodels, RF and Optical MEMS switches are discussed in next sections. The book concludes with the emphasis on MEMS based actuators

Generation and optimization of picosecond optical pulses for use in hybrid WDM/OTDM networks

The burgeoning demand for broadband services such as database queries, home shopping, video-on-demand, remote education, telemedicine and videoconferencing will push the existing networks to their limits. This demand was mainly fueled by the brisk proliferation of Personal Computers (PC) together with the exceptional increases in their storage capacity and processing capabilities and the widespread availability of the internet. Hence the necessity, to develop high-speed optical technologies in order to construct large capacity networks, arises. Two of the most popular multiplexing techniques available in the optical domain that are used in the building of such high capacity networks, are Wavelength Division Multiplexing (WDM) and Optical Time Division Multiplexing (OTDM). However merging these two techniques to form very high-speed hybrid WDM/OTDM networks brings about the merits of both multiplexing technologies. This thesis examines the development of one of the key components (picosecond optical pulses) associated to such high-speed systems. Recent analysis has shown that RZ format is superior to conventional NRZ systems as it is easier to compensate for dispersion and nonlinear effects in the fibre by employing soliton-like propagation. In addition to this development, the use of wavelength tunability for dynamic provisioning is another area that is actively researched on. Self-seeding of a gain switched Fabry Perot laser is shown to one of the simplest and cost effective methods of generating, transform limited optical pulses that are wavelength tunable over very wide ranges. One of the vital characteristics of the above mentioned pulse sources, is their Side Mode Suppression Ratio (SMSR). This thesis examines in detail how the pulse SMSR affects the performance of high-speed WDM/OTDM systems that employ self-seeded gain-switched pulse sources

Research and technology, 1990: Goddard Space Flight Center

Goddard celebrates 1990 as a banner year in space based astronomy. From above the Earth's obscuring atmosphere, four major orbiting observatories examined the heavens at wavelengths that spanned the electromagnetic spectrum. In the infrared and microwave, the Cosmic Background Explorer (COBE), measured the spectrum and angular distribution of the cosmic background radiation to extraordinary precision. In the optical and UV, the Hubble Space Telescope has returned spectacular high resolution images and spectra of a wealth of astronomical objects. The Goddard High Resolution Spectrograph has resolved dozens of UV spectral lines which are as yet unidentified because they have never before been seen in any astronomical spectrum. In x rays, the Roentgen Satellite has begun returning equally spectacular images of high energy objects within our own and other galaxies

Fabrication and characterisation of tellurite planar waveguides

Tellurite glasses, which contain Tellurium dioxide as the main component, have some remarkable optical properties which are well recognised and exploited in the bulk optics and fibre fields. They include a high acousto-optic figure of merit, wide mid infrared transparency, the highest optical nonlinearity amongst oxides, and excellent rare earth hosting, etc. Despite these attractive properties, until now, no one has succeeded in fabricating low loss planar waveguides in these materials. This work develops high quality optical planar waveguides in Tellurium dioxide for the first time. The project investigates the materials science for optical Tellurium dioxide films and discovers an appropriate waveguide fabrication method. The thin films have been fabricated by reactive radio frequency magnetron sputtering using a Tellurium target in an oxygen and argon atmosphere. Propagation losses at 1550nm in the planar films are 0.1dB/cm or lower in stoichiometric composition. The properties of films have been also found to be stable with thermal annealing up to 300 degree Celsius. Plasma etching of tellurite glasses has been systematically studied. High quality etching of Tellurium dioxide and chalcogenide glass films has been demonstrated with a Methane/Hydrogen/Argon gas mixture. As a result, a fabrication recipe which produces low loss (0.1dB/cm) planar waveguides has been discovered. The nonlinear coefficient of the sputtered TeO2 has been characterised by self-phase modulation (SPM) experiments and the second order nonlinear coefficient has been measured to be around 25 times that of silica. Significant signal conversion, -4dB, has achieved with large bandwidth of 30nm in the four-wave mixing (FWM) experiment pumped at 1550nm in a slightly normal dispersion waveguide. Erbium doped Tellurium oxide thin films have also been fabricated by co-sputtering of Erbium and Tellurium targets into an Oxygen and Argon atmosphere. The obtained films have been found to have good properties for Erbium doped waveguide amplifiers. The Erbium concentration can be controlled within the range of interest with Erbium/Tellurium ratios ranging from 0.1% to 3% or more. The 1.5 micrometre photoluminescence properties of the films are excellent with effective bandwidth of more that 60nm and intrinsic lifetime of order of 3ms. Despite the fact that there was OH contamination in the films, single mode Erbium doped waveguide amplifiers with high internal gain have been successfully obtained. The 1480nm pumped amplifier achieved internal gain from below 1520nm to beyond 1600nm. The peak gain of 2.8dB/cm and 40nm 3dB gain bandwidth have been accomplished. These results are a major stepping stone towards ""system-on-chip"" optical applications for telecom and mid infrared optics given the multifunctional nature of tellurite materials. -- provided by Candidate