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

Towards optical and potentiometric measurements of double layer structures and dynamics

My doctoral research pertains with developing accessible and technically simple methods to study the electric double layer. A complete and correct description of double layers formed when wetting charged surfaces with electrolytic solutions is of great practical importance. This phase boundary governs charge transport, energy storage and lubricating properties of interfaces. Currently, all techniques available to probe double layer structures and dynamics are rather technically demanding (e.g. electrochemical impedance spectroscopy, AFM and STM), or carry intrinsic limitations, such as when metal probes are employed, a situation where the probe element inevitably bears its own double layer making hard to extract data on the sample under analysis

Investigation of YAG:Ce Scintillating Fiber Properties Using Silicon Photomultipliers

The properties of thin, cerium activated, yttrium aluminum garnet (YAG:Ce), scintillating fiber-shaped crystals were investigated for particle tracking and calorimetric applications such as Compton imaging of Special Nuclear Material from remote platforms at standoff ranges. Silicon photomultipliers (SiPMs) are relatively new, efficient, single photon sensitive, solid-state photodiode arrays which are well suited for the readout of scintillating fibers. Using SiPMs, the scintillation decay time profiles of six 400 micrometers YAG:Ce fiber crystals were measured under alpha and gamma irradiation. Interestingly, the observed decay times in the thin fibers were substantially slower than values for bulk single crystal YAG:Ce reported in open scientific literature; possible explanations are explored. Both laser induced photoluminescence and alpha scintillation measurements were conducted to estimate the effective attenuation length of the YAG:Ce fibers. Using the measured attenuation lengths, position-of-interaction measurements were conducted to determine the achievable position resolution in YAG:Ce fibers using dual fiber end SiPM readouts. The measured results are compared to theoretical calculations and Monte Carlo simulations. Finally, improvements to the detector concept, including a formula to determine the best SiPM model based on device parameters and the Birks\u27 figure of merit of the scintillating material, are presented

Design and implementation of miniaturised capsule for autofluorescence detection with possible application to the bowel disease

Early signs of intestinal cancer may be detected through variations in tissue autofluorescence (AF), however current endoscope-based AF systems are unable to inspect the small intestine. This thesis describes the design, fabrication, implantation, testing and packaging of a wireless pill capable of detecting the autofluorescence from cancerous cells, and able to reach parts of the gastrointestinal tract that are inaccessible to endoscopes. The pill exploits the fact that there is a significant difference in the intensity of autofluorescence emitted by normal and cancerous tissues when excited by a blue or ultra violet light source. The intensity differences are detected using very sensitive light detectors. The pill has been developed in two stages. The first stage starts with using an off-chip multi-pixel photon counter (MPPC) device as a light detector. In the second stage, the light detector is integrated into an application specific integrated circuit (ASIC). The pill comprises of an ASIC, optical filters, an information processing unit and a radio transmission unit, to transmit acquired data to an external base station. Two ASICs have been fabricated, the first stage of this work involved implementing an ASIC that contains two main blocks; the first block is capable of providing a variable DC voltage more than 72 V from a 3 V input to bias the MPPC device. The second main block is a front-end consisting of a high speed transimpedance amplifier (TIA) and voltage amplifiers to capture the very small current pulses produced by the MPPC. The second ASIC contains a high voltage charge pump up to (37.9 V) integrated with a single photon avalanche detector (SPAD). The charge pump is used to bias the SPAD above its breakdown voltage and therefore operate the device in Geiger mode. The SPAD was designed to operate in the visible region where its photon detection efficiency (PDE) peaks at 465 nm, which is near to human tissues autofluorescence peaking region (520±10 nm). The use of the ultra low light detector to detect the autofluorescence permits a lower excitation light intensity and therefore lower overall power consumption. The two ASICs were fabricated using a commercial triple-well high-voltage CMOS process. The complete device operates at 3V and draws an average of 7.1mA, enabling up to 23 hours of continuous operation from two 165mAh SR44 batteries

Design and Verification of an Optical System to Interrogate Dermally-implanted Microparticle Sensors

Diabetes mellitus affects 25.8 million Americans (8.3%) and over 300 million people worldwide. Clinical trials indicate that proper management of blood glucose levels is critical in preventing or delaying complications associated with diabetes. Thus, there is a common need to monitor and manage blood glucose properly for people with diabetes. However, the patients’ compliance for recommended monitoring frequency is low due to the pain and inconvenience of current standard finger-pricking tests. To promote patient adherence to the recommended self-monitoring frequency, non-invasive/ minimally invasive glucose testing approaches are needed. Luminescent microparticle sensor is an attractive solution. For these sensors to be deployed in vivo, a matched optical system is needed to interrogate dermally-implanted sensors. This research project investigated the light propagation in skin and the interaction with implants using Monte Carlo modeling. The results of the modeling were used to design an optical system with high interrogation and collection efficiency (40~300 times improvement). The optical system was then constructed and evaluated experimentally. A stable skin phantom mimicking the optical properties of human skin was developed as a permanent evaluation medium to minimize the use of animals. The optical properties of the skin phantom matched the maximum published values of human skin in scattering and absorption over the spectral range of 540~700nm in order to avoid overestimation of the capability of the system. The significant photon loss observed at the connection between the designed system and a commercial spectrometer was overcome using two optimized designs: a two-detector system and a customized low-resolution spectrometer system. Both optimization approaches effectively address the photon loss problem and each showed good SNR (>100) while maintaining a sufficient system resolution for use with fluorescent materials. Both systems are suitable for luminescence measurement, because broad bands of the luminescent spectrum are of interest. In the future, either system can be easily modified into a more compact system (e.g. handheld), and it can be directly coupled to an analog-to-digital converter and integrated circuits offering potential for a single compact and portable device for field use with luminescent diagnostic systems as well as implanted sensors

Fabrication of electroluminescent silicon diodes by plasma ion implantation

This thesis describes the fabrication and testing of electroluminescent diodes made from silicon subjected to plasma ion implantation. A silicon-compatible, electrically driven light source is desired to increase the speed and efficiency of short-range data transfer in the communications and computing industries. As it is an indirect band gap material, ordinary silicon is too inefficient a light source to be useful for these applications. Past experiments have demonstrated that modifying the structural properties of the crystal can enhance its luminescence properties, and that light ion implantation is capable of achieving this effect. This research investigates the relationship between the ion implantation processing parameters, the post-implantation annealing temperature, and the observable electroluminescence from the resulting silicon diodes. Prior to the creation of electroluminescent devices, much work was done to improve the efficiency and reliability of the fabrication procedure. A numerical algorithm was devised to analyze Langmuir probe data in order to improve estimates of implanted ion fluence. A new sweeping power supply to drive current to the probe was designed, built, and tested. A custom software package was developed to improve the speed and reliability of plasma ion implantation experiments, and another piece of software was made to facilitate the viewing and analysis of spectra measured from the finished silicon LEDs. Several dozen silicon diodes were produced from wafers implanted with hydrogen, helium, and deuterium, using a variety of implanted ion doses and post-implantation annealing conditions. One additional device was fabricated out of unimplanted, unannealed silicon. Most devices, including the unimplanted device, were electroluminescent at visible wavelengths to some degree. The intensity and spectrum of light emission from each device were measured. The results suggest that the observed luminescence originated from the native oxide layer on the surface of the ion-implanted silicon, but that the intensity of luminescence could be enhanced with a carefully chosen ion implantation and annealing procedure

Design of broadband high-efficiency superconducting-nanowire single photon detectors

In this paper several designs to maximize the absorption efficiency of superconducting-nanowire single-photon detectors are investigated. Using a simple optical cavity consisting of a gold mirror and a SiO2 layer, the absorption efficiency can be boosted to over 97%: this result is confirmed experimentally by the realization of an NbTiN-based detector having an overall system detection efficiency of 85% at 1.31 micrometers. Calculations show that by sandwiching the nanowire between two dielectric Bragg reflectors, unity absorption (> 99.9%) could be reached at the peak wavelength for optimized structures. To achieve broadband high efficiency, a different approach is considered: a waveguide-coupled detector. The calculations performed in this work show that, by correctly dimensioning the waveguide and the nanowire, polarization-insensitive detectors absorbing more than 95% of the injected photons over a wavelength range of several hundred nm can be designed. We propose a detector design making use of GaN/AlN waveguides, since these materials allow lattice-matched epitaxial deposition of Nb(Ti)N films and are transparent on a very wide wavelength range