Large area CMOS active pixel sensor x‐ray imager for digital breast tomosynthesis: Analysis, modeling, and characterization

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134791/1/mp2368.pd

The SuperCam Instrument Suite on the Mars 2020 Rover: Science Objectives and Mast-Unit Description

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds

High repetition rate temperature and velocity Imaging in turbulent flows using thermographic phosphors

Turbulent flows involving heat transfer and chemical reactions are prevalent in a huge range of applications such as combustors and engines, boilers, and heating and cooling devices. Directly measuring important variables using laser-based techniques has significantly contributed to our understanding of the underlying flow physics. However, many flows of interest exhibit infrequent or oscillatory behaviour, such as flame extinction or instabilities in thermal boundary layers. Capturing the flow dynamics requires simultaneous, two-dimensional temperature and velocity measurements at sampling rates commensurate with turbulent timescales. Typically this means measuring many thousands of temperature and velocity fields per second, yet there are no high repetition rate diagnostics for temperature imaging in practical, oxygen-containing systems, with the essential capability of simultaneous velocity measurements. This thesis presents a novel laser-based imaging technique based on thermographic phosphor particles. There are a huge variety of thermographic phosphors, which are solid materials with luminescence properties that can be exploited for remote thermometry. Here, phosphor particles are seeded into the flow as a tracer. An appropriate phosphor must be selected, and the particle size chosen so that the particle temperature and velocity rapidly assume that of the surrounding fluid. The particles are probed using high-speed lasers and their luminescence and scattering signals are detected using high-speed cameras to measure the flow temperature and velocity at kHz repetition rates. The development of this method is described in detail. Using the thermographic phosphor BAM:Eu, examples of simultaneous time-resolved measurements are presented in turbulent air flows between 300 and 500 K, consisting of a heated jet (Re = 10,000) and also a flow behind a heated cylinder (Re = 700). The technique permits kHz-rate temperature imaging in oxygen-containing environments. These combined diagnostics currently provide a unique capability for the investigation of transient, coupled heat and mass transfer phenomena in turbulent flows of practical engineering importance. A second objective of this work is to improve the precision of the temperature measurement. The characterisation of a different thermographic phosphor with a high temperature sensitivity, zinc oxide (ZnO), is also reported. Temperature imaging using these tracer particles is demonstrated in a jet (Re = 2,000) heated to 363 K, with a temperature precision of 1%. This extends the capabilities of this versatile technique toward the study of flows with small temperature variations. Also, unlike the majority of phosphors previously investigated for thermometry, this phosphor is a semiconductor. Exploiting the temperature-dependent luminescence of this class of materials presents interesting new opportunities for remote temperature sensing.Open Acces

Development of a Portable CMOS Time-Domain Fluorescence Lifetime Imager

Modern laboratory equipments to measure the excited-state lifetime of fluorophores usually include an expensive picosecond pulsed-laser excitation source, a fragile photomultiplier tube, and a large instrument body for optics. A portable and robust device to make fluorescence lifetime measurement in nanosecond scale is of great attraction for chemists and biologists. This dissertation reports the development of a portable LED time-domain fluorimeter from an all-solid-state discrete-component prototype to its advanced CMOS integrated circuit implementation. The motivation of the research is to develop a multiplexed fluorimeter for point-of-care diagnosis. Instruments developed by this novel method have higher fill factor, are more portable, and are fabricated at lower cost

Time resolved single photon imaging in Nanometer Scale CMOS technology

Time resolved imaging is concerned with the measurement of photon arrival time. It has a wealth of emerging applications including biomedical uses such as fluorescence lifetime microscopy and positron emission tomography, as well as laser ranging and imaging in three dimensions. The impact of time resolved imaging on human life is significant: it can be used to identify cancerous cells in-vivo, how well new drugs may perform, or to guide a robot around a factory or hospital. Two essential building blocks of a time resolved imaging system are a photon detector capable of sensing single photons, and fast time resolvers that can measure the time of flight of light to picosecond resolution. In order to address these emerging applications, miniaturised, single-chip, integrated arrays of photon detectors and time resolvers must be developed with state of the art performance and low cost. The goal of this research is therefore the design, layout and verification of arrays of low noise Single Photon Avalanche Diodes (SPADs) together with high resolution Time-Digital Converters (TDCs) using an advanced silicon fabrication process. The research reported in this Thesis was carried out as part of the E.U. funded Megaframe FP6 Project. A 32x32 pixel, one million frames per second, time correlated imaging device has been designed, simulated and fabricated using a 130nm CMOS Imaging process from ST Microelectronics. The imager array has been implemented together with required support cells in order to transmit data off chip at high speed as well as providing a means of device control, test and calibration. The fabricated imaging device successfully demonstrates the research objectives. The Thesis presents details of design, simulation and characterisation results of the elements of the Megaframe device which were the author’s own work. Highlights of the results include the smallest and lowest noise SPAD devices yet published for this class of fabrication process and an imaging array capable of recording single photon arrivals every microsecond, with a minimum time resolution of fifty picoseconds and single bit linearity

Spectral Enhancement of Organic Photodetectors

Solution-processed photodiodes with infrared sensitivities at wavelengths beyond the bandgap of silicon would be a significant advance towards cost-effective imaging. Colloidal quantum dots are highly suitable as infrared absorbers for photodetection. The concept of organic bulk heterojunctions sensitized with PbS nanocrystalline was proved with efficient near-infrared detection up to 1.8 mm for NIR imaging on active matrix TFT backplanes and demonstrated x-ray sensitivity

Spectral Enhancement of Organic Photodetectors

Solution-processed photodiodes with infrared sensitivities at wavelengths beyond the bandgap of silicon would be a significant advance towards cost-effective imaging. Colloidal quantum dots are highly suitable as infrared absorbers for photodetection. The concept of organic bulk heterojunctions sensitized with PbS nanocrystalline was proved with efficient near-infrared detection up to 1.8 mm for NIR imaging on active matrix TFT backplanes and demonstrated x-ray sensitivity