Hilbert Based Testing of ADC Differential Non-linearity Using Wavelet Transform Algorithms

In testing Mixed Signal Devices such as Analog to Digital and Digital to Analog Converters, some dynamic parameters, such as Differential Non-Linearity and Integral Non-linearity, are very critical to evaluating devises performance. However, such analysis has been notorious for complexity and massive compiling process. Therefore, this research will focus on testing dynamic parameters such as Differential Non-Linearity by simulating numerous numbers of bits Analog to Digital Converters and test the output signals base on new testing algorithms of Wavelet transform based on Hilbert process. Such a new testing algorithm should enhance the testing process by using less compiling data samples and prompt testing results. In addition, new testing results will be compared with the conventional testing process of Histogram algorithms for accuracy and enactment

Bi-Linear Homogeneity Enforced Calibration for Pipelined ADCs

Pipelined analog-to-digital converters (ADCs) are key enablers in many state-of-the-art signal processing systems with high sampling rates. In addition to high sampling rates, such systems often demand a high linearity. To meet these challenging linearity requirements, ADC calibration techniques were heavily investigated throughout the past decades. One limitation in ADC calibration is the need for a precisely known test signal. In our previous work, we proposed the homogeneity enforced calibration (HEC) approach, which circumvents this need by consecutively feeding a test signal and a scaled version of it into the ADC. The calibration itself is performed using only the corresponding output samples, such that the test signal can remain unknown. On the downside, the HEC approach requires the option to accurately scale the test signal, impeding an on-chip implementation. In this work, we provide a thorough analysis of the HEC approach, including the effects of an inaccurately scaled test signal. Furthermore, the bi-linear homogeneity enforced calibration (BL-HEC) approach is introduced and suggested to account for an inaccurate scaling and, therefore, to facilitate an on-chip implementation. In addition, a comprehensive stability and convergence analysis of the BL-HEC approach is carried out. Finally, we verify our concept with simulations.Comment: 12 pages, 5 figure

The application of the capacitive division technique to wide-field time-resolved fluorescence microscopy

Capacitive division and other charge-sharing techniques have become ubiquitous within modern technology. Almost all touchscreen devices depend on some form of charge sharing mechanism. The Capacitive-Division Imaging Readout, C-DIR, scheme developed for space/astronomy applications, is a proven concept which has benefited from widespread publication and several iterations of prototyping. In this study, we borrowed this idea and assessed its application in the field of life sciences, specifically, fluorescence lifetime imaging microscopy (FLIM). Firstly, the composite C-DIR camera system was developed using a prototype anode developed by Lapington et al in combination with advanced photomultiplier tube technology developed by Photek Limited, and ultra-fast NINO ASIC and high performance time-to-digital converter, HPTDC, readout electronics developed by CERN. Several issues like signal noise, timing jitter and image distortion required special attention to successfully tune the C-DIR system for obtaining FLIM measurements. The C-DIR was characterized in the context of current detector technologies used for time-resolved applications. The maximum achievable global event rate was determined to be a USB 2.0 hard limit of about 1MHz. The spatial resolution and timing performance were identified as 0.5 line-pairs/mm and 200ps FWHM, respectively, which was comparable to other wide-field fluorescence lifetime cameras. These results provided the basis for using the system in a real situation. Before this was possible, however, it was necessary to engineer a bespoke software platform for data acquisition which could cope with the data rates and reduce raw data emerging from the C-DIR system, producing a format compatible with widely used fitting software. The final stage of the project involved using the C-DIR for real science by reproducing real world experiments which allow for a fitness test of the system in the field. The first experiment involved a calcium calibration where the C-DIR system was calibrated using FLIM on a series of calcium buffers of known concentrations. This C-DIR was able accurately recover the lifetime values from the calcium buffers. The second shorter experiment involved using the calibrated system for the quantification of calcium within living tissue samples using fluorescence lifetime imaging. Results were consistent with those published in the literature which solidified the position of the C-DIR as a viable option for time-resolved fluorescence microscopy

Study of a prototype module of a precision time-of-flight detector for particle identification at low momentum

In this thesis, Time Of internally Reflected Cherenkov light detector (TORCH), proposed for the LHCb Upgrade to perform three-sigma separation between kaon and pion up to 10 GeV/c, was studied. TORCH is designed to add significant particle identification capability to the existing LHCb system based on two gas Ring Imaging Cherenkov detectors. TORCH would be placed at ~10 m from the interaction point, where the flight time difference between a primary pion and kaon is 37.5 ps. TORCH will give a pion-kaon separation of three sigma at 10 GeV/c from the flight time using the Cherenkov photons generated by the charged particle in a 1 cm-thick quartz plate. In order to calculate accurately the flight time in a busy LHCb environment, Cherenkov angle and photon detection time information, as well as the momentum information from the tracking detector are included in the analysis. For the required TORCH performance, the flight time difference must be measured with a resolution of better than 70 ps for a single Cherenkov photon. In order to demonstrate the required performance, the intrinsic time resolution of the photon detector and electronics jitter have been investigated, firstly with commercially available Micro-Channel Plate Photo Multiplier Tubes (MCP-PMT) and electronics, then custom-made Multi-Channel MCP-PMT with custom-made electronics, which are designed for the TORCH R&D. The Multi-Channel MCP-PMT has been developed in collaboration with industry. For the custom electronics, NINO, an ASIC chip developed for the Time of Flight detector of the ALICE experiment was used as well as the HPTDC ASIC chip, which is being used by the ATLAS, CMS and ALICE experiments. Important characteristics such as the linearity and time walk have been carefully analysed and a method to correct biases introduced by those characteristics has been developed. TORCH optics must propagate the Cherenkov photons to the photocathode of the Multichannel MCPMT with minimum loss. On the other hand, spectra of photons reaching the photocathode should not be too wide in order to limit the chromatic error. All the optical components have been tested with a stand-alone system and results are compared with simulation studies. A small scale TORCH prototype has been constructed to test the system with a charged-particle beam and results are being analysed

Microwave resonant sensors

Microwave resonant sensors use the spectral characterisation of a resonator to make high sensitivity measurements of material electromagnetic properties at GHz frequencies. They have been applied to a wide range of industrial and scientific measurements, and used to study a diversity of physical phenomena. Recently, a number of challenging dynamic applications have been developed that require very high speed and high performance, such as kinetic inductance detectors and scanning microwave microscopes. Others, such as sensors for miniaturised fluidic systems and non-invasive blood glucose sensors, also require low system cost and small footprint. This thesis investigates new and improved techniques for implementing microwave resonant sensor systems, aiming to enhance their suitability for such demanding tasks. This was achieved through several original contributions: new insights into coupling, dynamics, and statistical properties of sensors; a hardware implementation of a realtime multitone readout system; and the development of efficient signal processing algorithms for the extraction of sensor measurements from resonator response data. The performance of this improved sensor system was verified through a number of novel measurements, achieving a higher sampling rate than the best available technology yet with equivalent accuracy and precision. At the same time, these experiments revealed unforeseen applications in liquid metrology and precision microwave heating of miniature flow systems.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Image Processing and Analysis for Preclinical and Clinical Applications

Radiomics is one of the most successful branches of research in the field of image processing and analysis, as it provides valuable quantitative information for the personalized medicine. It has the potential to discover features of the disease that cannot be appreciated with the naked eye in both preclinical and clinical studies. In general, all quantitative approaches based on biomedical images, such as positron emission tomography (PET), computed tomography (CT) and magnetic resonance imaging (MRI), have a positive clinical impact in the detection of biological processes and diseases as well as in predicting response to treatment. This Special Issue, “Image Processing and Analysis for Preclinical and Clinical Applications”, addresses some gaps in this field to improve the quality of research in the clinical and preclinical environment. It consists of fourteen peer-reviewed papers covering a range of topics and applications related to biomedical image processing and analysis

Microwave resonant sensors

Microwave resonant sensors use the spectral characterisation of a resonator to make high sensitivity measurements of material electromagnetic properties at GHz frequencies. They have been applied to a wide range of industrial and scientific measurements, and used to study a diversity of physical phenomena. Recently, a number of challenging dynamic applications have been developed that require very high speed and high performance, such as kinetic inductance detectors and scanning microwave microscopes. Others, such as sensors for miniaturised fluidic systems and non-invasive blood glucose sensors, also require low system cost and small footprint. This thesis investigates new and improved techniques for implementing microwave resonant sensor systems, aiming to enhance their suitability for such demanding tasks. This was achieved through several original contributions: new insights into coupling, dynamics, and statistical properties of sensors; a hardware implementation of a realtime multitone readout system; and the development of efficient signal processing algorithms for the extraction of sensor measurements from resonator response data. The performance of this improved sensor system was verified through a number of novel measurements, achieving a higher sampling rate than the best available technology yet with equivalent accuracy and precision. At the same time, these experiments revealed unforeseen applications in liquid metrology and precision microwave heating of miniature flow systems

High-Speed Wide-Field Time-Correlated Single-Photon Counting Fluorescence Lifetime Imaging Microscopy

Fluorescence microscopy is a powerful imaging technique used in the biological sciences to identify labeled components of a sample with specificity. This is usually accomplished through labeling with fluorescent dyes, isolating these dyes by their spectral signatures with optical filters, and recording the intensity of the fluorescent response. Although these techniques are widely used, fluorescence intensity images can be negatively affected by a variety of factors that impact the fluorescence intensity. Fluorescence lifetime imaging microscopy (FLIM) is an imaging technique that is relatively immune to intensity fluctuations and also provides the unique ability to directly monitor the microenvironment surrounding a fluorophore. Despite the benefits associated with FLIM, the applications to which it is applied are fairly limited due to long image acquisition times and high cost of traditional hardware. Recent advances in complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diodes (SPADs) have enabled the design of low-cost imaging arrays that are capable of recording lifetime images with acquisition times greater than one order of magnitude faster than existing systems. However, these SPAD arrays have yet to realize the full potential of the technology due to limitations in their ability to handle the vast amount of data generated during the commonly used time-correlated single-photon counting (TCSPC) lifetime imaging technique. This thesis presents the design, implementation, characterization, and demonstration of a high speed FLIM imaging system. The components of this design include a CMOS imager chip in a standard 0.13 μm technology containing a custom CMOS SPAD, a 64-by-64 array of these SPADs, pixel control circuitry, independent time-to-digital converters (TDCs), a FLIM specific datapath, and high bandwidth output buffers. In addition to the CMOS imaging array, a complete system was designed and implemented using a printed circuit board (PCB) for capturing data from the imager, creating histograms for the photon arrival data using field-programmable gate arrays, and transferring the data to a computer using a cabled PCIe interface. Finally, software is used to communicate between the imaging system and a computer.The dark count rate of the SPAD was measured to be only 231 Hz at room temperature while maintaining a photon detection probability of up to 30\%. TDCs included on the array have a 62.5 ps resolution and a 64 ns range, which is suitable for measuring the lifetime of most biological fluorophores. Additionally, the on-chip datapath was designed to handle continuous data transfers at rates capable of supporting TCSPC-based lifetime imaging at 100 frames per second. The system level implementation also provides sufficient data throughput for transferring up to 750 frames per second from the imaging system to a computer. The lifetime imaging system was characterized using standard techniques for evaluating SPAD performance and an electrical delay signal for measuring the TDC performance. This thesis concludes with a demonstration of TCSPC-FLIM imaging at 100 frames per second -- the fastest 64-by-64 TCSPC FLIM that has been demonstrated. This system overcomes some of the limitations of existing FLIM systems and has the potential to enable new application domains in dynamic FLIM imaging

Development of whole-heart myocardial perfusion magnetic resonance imaging

Myocardial perfusion imaging is of huge importance for the detection of coronary artery disease (CAD), one of the leading causes of morbidity and mortality worldwide, as it can provide non-invasive detection at the early stages of the disease. Magnetic resonance imaging (MRI) can assess myocardial perfusion by capturing the rst-pass perfusion (FPP) of a gadolinium-based contrast agent (GBCA), which is now a well-established technique and compares well with other modalities. However, current MRI methods are restricted by their limited coverage of the left ventricle. Interest has therefore grown in 3D volumetric \whole-heart" FPP by MRI, although many challenges currently limit this. For this thesis, myocardial perfusion assessment in general, and 3D whole-heart FPP in particular, were reviewed in depth, alongside MRI techniques important for achieving 3D FPP. From this, a 3D `stack-of-stars' (SOS) FPP sequence was developed with the aim of addressing some current limitations. These included the breath-hold requirement during GBCA rst-pass, long 3D shot durations corrupted by cardiac motion, and a propensity for artefacts in FPP. Parallel imaging and compressed sensing were investigated for accelerating whole-heart FPP, with modi cations presented to potentially improve robustness to free-breathing. Novel sequences were developed that were capable of individually improving some current sequence limits, including spatial resolution and signal-to-noise ratio, although with some sacri ces. A nal 3D SOS FPP technique was developed and tested at stress during free-breathing examinations of CAD patients and healthy volunteers. This enabled the rst known detection of an inducible perfusion defect with a free-breathing, compressed sensing, 3D FPP sequence; however, further investigation into the diagnostic performance is required. Simulations were performed to analyse potential artefacts in 3D FPP, as well as to examine ways towards further optimisation of 3D SOS FPP. The nal chapter discusses some limitations of the work and proposes opportunities for further investigation.Open Acces