Investigation of a Space Delta Technology Facility (SDTF) for Spacelab

The Space Data Technology Facility (SDTF) would have the role of supporting a wide range of data technology related demonstrations which might be performed on Spacelab. The SDTF design is incorporated primarily in one single width standardized Spacelab rack. It consists of various display, control and data handling components together with interfaces with the demonstration-specific equipment and Spacelab. To arrive at this design a wide range of data related technologies and potential demonstrations were also investigated. One demonstration concerned with online image rectification and registration was developed in some depth

Event-based Vision: A Survey

Event cameras are bio-inspired sensors that differ from conventional frame cameras: Instead of capturing images at a fixed rate, they asynchronously measure per-pixel brightness changes, and output a stream of events that encode the time, location and sign of the brightness changes. Event cameras offer attractive properties compared to traditional cameras: high temporal resolution (in the order of microseconds), very high dynamic range (140 dB vs. 60 dB), low power consumption, and high pixel bandwidth (on the order of kHz) resulting in reduced motion blur. Hence, event cameras have a large potential for robotics and computer vision in challenging scenarios for traditional cameras, such as low-latency, high speed, and high dynamic range. However, novel methods are required to process the unconventional output of these sensors in order to unlock their potential. This paper provides a comprehensive overview of the emerging field of event-based vision, with a focus on the applications and the algorithms developed to unlock the outstanding properties of event cameras. We present event cameras from their working principle, the actual sensors that are available and the tasks that they have been used for, from low-level vision (feature detection and tracking, optic flow, etc.) to high-level vision (reconstruction, segmentation, recognition). We also discuss the techniques developed to process events, including learning-based techniques, as well as specialized processors for these novel sensors, such as spiking neural networks. Additionally, we highlight the challenges that remain to be tackled and the opportunities that lie ahead in the search for a more efficient, bio-inspired way for machines to perceive and interact with the world

Towards Real-Time Novel View Synthesis Using Visual Hulls

This thesis discusses fast novel view synthesis from multiple images taken from different viewpoints. We propose several new algorithms that take advantage of modern graphics hardware to create novel views. Although different approaches are explored, one geometry representation, the visual hull, is employed throughout our work. First the visual hull plays an auxiliary role and assists in reconstruction of depth maps that are utilized for novel view synthesis. Then we treat the visual hull as the principal geometry representation of scene objects. A hardwareaccelerated approach is presented to reconstruct and render visual hulls directly from a set of silhouette images. The reconstruction is embedded in the rendering process and accomplished with an alpha map trimming technique. We go on by combining this technique with hardware-accelerated CSG reconstruction to improve the rendering quality of visual hulls. Finally, photometric information is exploited to overcome an inherent limitation of the visual hull. All algorithms are implemented on a distributed system. Novel views are generated at interactive or real-time frame rates.In dieser Dissertation werden mehrere Verfahren vorgestellt, mit deren Hilfe neue Ansichten einer Szene aus mehreren Bildströmen errechnet werden können. Die Bildströme werden hierzu aus unterschiedlichen Blickwinkeln auf die Szene aufgezeichnet. Wir schlagen mehrere Algorithmen vor, welche die Funktionen moderner Grafikhardware ausnutzen, um die neuen Ansichten zu errechnen. Obwohl die Verfahren sich methodisch unterscheiden, basieren sie auf der gleichen Geometriedarstellung, der Visual Hull. In der ersten Methode spielt die Visual Hull eine unterstützende Rolle bei der Rekonstruktion von Tiefenbildern, die zur Erzeugung neuer Ansichten verwendet werden. In den nachfolgend vorgestellten Verfahren dient die Visual Hull primär der Repräsentation von Objekten in einer Szene. Eine hardwarebeschleunigte Methode, um Visual Hulls direkt aus mehreren Silhouettenbildern zu rekonstruieren und zu rendern, wird vorgestellt. Das Rekonstruktionsverfahren ist hierbei Bestandteil der Renderingmethode und basiert auf einer Alpha Map Trimming Technik. Ein weiterer Algorithmus verbessert die Qualitaet der gerenderten Visual Hulls, indem das Alpha-Map-basierte Verfahren mit einer hardware-beschleunigten CSG Rekonstruktiontechnik kombiniert wird. Eine vierte Methode nutzt zusaetzlich photometrische Information aus, um eine grundlegende Beschraenkung des Visual-Hull-Ansatzes zu umgehen. Alle Verfahren ermoeglichen die interaktive oder Echtzeit- Erzeugung neuer Ansichten

The ABC130 barrel module prototyping programme for the ATLAS strip tracker

For the Phase-II Upgrade of the ATLAS Detector, its Inner Detector, consisting of silicon pixel, silicon strip and transition radiation sub-detectors, will be replaced with an all new 100 % silicon tracker, composed of a pixel tracker at inner radii and a strip tracker at outer radii. The future ATLAS strip tracker will include 11,000 silicon sensor modules in the central region (barrel) and 7,000 modules in the forward region (end-caps), which are foreseen to be constructed over a period of 3.5 years. The construction of each module consists of a series of assembly and quality control steps, which were engineered to be identical for all production sites. In order to develop the tooling and procedures for assembly and testing of these modules, two series of major prototyping programs were conducted: an early program using readout chips designed using a 250 nm fabrication process (ABCN-25) and a subsequent program using a follow-up chip set made using 130 nm processing (ABC130 and HCC130 chips). This second generation of readout chips was used for an extensive prototyping program that produced around 100 barrel-type modules and contributed significantly to the development of the final module layout. This paper gives an overview of the components used in ABC130 barrel modules, their assembly procedure and findings resulting from their tests.Comment: 82 pages, 66 figure

Photodiodes and Image Sensors on Mechanically Flexible Ultra-Thin Silicon Chips-in-Foil

CMOS-Bildsensoren haben in den letzten zwei Jahrzehnten enorme technologische Fortschritte erfahren und sich als eine wettbewerbsfähige Alternative gegenüber CCDBildsensoren auf dem Markt etabliert. Reduziert man die Chipdicke von CMOSBildsensoren von normal 725 μm auf ≤ 30 μm, erhält man mechanisch flexible Bildaufnehmer. Gewölbte CMOS-Bildsensoren würden für die optische Wahrnehmung völlig neue Möglichkeiten eröffnen (wie z. B. bei Insektenaugen). Betrachtet man die auf dem Chip integrierten Bauelemente und Schaltungen unter mechanischen Spannungen, stellt man fest, dass ihre elektrischen und optoelektronischen Eigenschaften von der ausgeübten mechanischen Spannung beeinflusst werden. Für den technischen Einsatz ist eine vom mechanischen Zustand des Bildsensors unbeinflusste Funktion erforderlich. Der Einfluss von mechanischer Spannung auf die Bauelemente- und Schaltungs-Charakteristiken und seine Minimierung bzw. Kompensation sind daher von besonderem Interesse. In dieser Arbeit wurden die optischen und elektrischen Eigenschaften von passiven und aktiven Bauelementen, sowie integrierten Schaltungen auf monokristallinen gedünnten flexiblen Siliziumchips unter mechanischen Spannungen untersucht. Der Einfluss von mechanischen Spannungen auf optische Eigenschaften (spektrale Lichtempfindlichkeit, Dunkelstrom und elektronisches Rauschen) einzelner p-n-Übergang basierter Photodioden und Bildsensorarrays auf (100)-Siliziumwafern wurde theoretisch modelliert und experimentell charakterisiert. Weiterhin wurden die elektrischen Eigenschaften (Ladungsträgerbeweglichkeit, Schwellenspannung, 1/f Rauschen) von MOSFeldeffekttransistoren in Bezug auf mechanischen Spannungen charakterisiert und ihre Abhängigkeit von der Orientierung zur Kristallorientierung des Substrats untersucht. Integrierte Schaltungen, wie Bandgap-Referenzspannungsquellen, Operationsverstärker und SC-basierte Schaltungen wurden unter mechanischen Spannungen theoretisch betrachtet, entworfen, gefertigt und experimentell charakterisiert. Mit Hilfe des in dieser Arbeit vorgeschlagenen und eingesetzten Simulationskonzeptes, ist die Schaltungssimulation der obengenannten Abhängigkeiten möglich. Dadurch hat der Schaltungsentwickler die Möglichkeit Schaltungskonzepte zur Kompensation oder Minimierung der von der mechanischen Spannung hervorgerufenen Einflüsse zu simulieren. In dieser Hinsicht werden Schaltungskonzepte und Design-Regeln präsentiert, die den Einfluss von mechanischen Spannungen auf Bildsensorchips berücksichtigen und minimieren. Im Rahmen dieser Arbeit wurde darüber hinaus ein mechanisch flexibler Bildsensorchip entworfen, simuliert und gefertigt, dessen Betrieb unabhängig von der ausgeübten mechanischen Spannung ist. Der ultra-dünne 20 μm Bildsensorchip ist geeignet auf zylindrisch gewölbte Oberflächen aufgebracht zu werden und erlaubt die Aufnahme raumrichtungsselektiver optischer Informationen im Sinne eines Panoramablicks.CMOS image sensors (CIS) have experienced the last two decades tremendous technological advances rendering them a viable alternative to charged couple devices (CCDs) not only in high volume applications but also in applications which require high spatial and temporal resolution, high dynamic range, low noise or high sensitivity levels. CISs are employed due to their increased chip thickness (ca. 750 μm) solely in the traditional planar image acquisition. If the chip thickness could be reduced down to or less than 30 μm, the silicon chips would become mechanically flexible. Such flexible CISs could substantially extend the application spectrum of image sensors in non-conventional imaging systems (e.g. imitating insect vision). However, the on-chip integrated devices and circuits exhibit stress-induced changes on their electrical and optoelectronic characteristics. Since a stress independent operation is striven, the minimization or compensation of the influence of mechanical stress on the characteristics of devices and circuits is of great interest. In this work optical and electrical properties of passive and active devices as well as integrated circuits on ultra-thin monolithic flexible silicon chips have been investigated under the application of mechanical stress. The influence of mechanical stress on the optical characteristics (spectral sensitivity, dark current and electronic noise) of p-n junction based photodiodes and image sensor chips on (100)-silicon wafers have been theoretically modeled and experimentally characterized. Moreover, the electrical characteristics (carrier mobility, threshold voltage and 1/f noise) of mechanically strained MOS field-effect transistors and their dependence on the channel orientation on the substrate have been investigated. Integrated circuits such as bandgap reference voltage sources, operational amplifiers and switched capacitor (SC) based circuits have been theoretically treated, designed, fabricated and experimentally characterized. Within this framework a simulation technique has been proposed and deployed, which allows the simulation of the above mentioned stress dependence on device and circuit level. The analog circuit designer can employ the simulation technique toward the proposal of circuit topologies or techniques, which minimize or compensate the strain-induced changes on the circuit operation. In this direction, circuit concepts and design rules are proposed, which minimize the influence of mechanical stress on flexible CIS chips. Within the scope of this work, a mechanically flexible CMOS image sensor chip has been designed, simulated and fabricated, which operation is stress independent. The developed ultra-thin 20 μm CIS chip can be wrapped around a cylindrically curved surface and thus record panoramic optical information

Bulk-micromachined mass airflow sensor fabrication and testing methodology for an undergraduate microfabrication course.

In July 1995, National Science Foundation Award # 9551869 funded the development of a new inter-disciplinary microfabrication course under the primary leadership of Dr. Kevin Walsh at the University of Louisville. Along with this award, the completed construction of a new building in 1996 that contained a class 1000/100 cleanroom laboratory facilitated the development of the course. Moreover, curricula had to be completed to provide students with practical, hands-on experience in building Micro Electro-Mechanical Systems (MEMS) devices using processes and methodologies introduced in the course. Dr. Walsh wanted to include a mass airflow sensor in his portfolio of total possible devices students could build in the cleanroom lab for the course. This document describes the design of a bulk-micromachined, monolithic, mass airflow sensor with a thermally-isolated, thin-film, dielectric, microbridge/diaphragm design. In addition, several fabrication methodologies were explored, as well as a means to test and evaluate the sensors for this undergraduate class laboratory. The mass airflow sensor architecture chosen was based upon a closed-loop-control,microelectronic thermal (hot-wire) anemometer design, which was first developed and presented by Johnson, Higashi, et. al. at Honeywell in the mid 1980s [2]. Two separate photomask sets were developed using L-Edit™ software (by Tanner Research), with each set including multiple geometric variations of a dual/triple microbridge/cantilever flow sensor structure to be suspended over a precision, anisotropically-etched pit, integrated onto a (100) silicon substrate. Four primary structural fabrication strategies were explored to produce the thin-film material for the flow sensors: (1) RF planar magnetron sputter-deposited 1 m m -thick silicon nitride microbridges/cantilevers; (2) anodically-bonded-and-machined 20-30 m m -thick borosilicate glass diaphragms; (3) spin-on-glass microbridges/cantilevers; and (4) low-stress, 0.5 m m -thick, LPCVD silicon nitride microbridges/cantilevers. Four resistor metallizations were separately evaluated: permalloy (Ni81Fe19), chromium, titanium, and platinum. A process was developed and documented to successfully fabricate flow sensors with low stress LPCVD silicon nitride microbridges/cantilevers. DC planar magnetron sputterdeposited platinum thin-film resistors (with a ~120 nm-thick RF planar magnetron sputterdeposited chromium adhesion layer), with nominal thicknesses of ~56 – 70 nm, were delineated by photolithographic imaging techniques. The resistors had measured Temperature Coefficients of Resistance (TCR) in the range of 1.93 – 2.25 x10-3 W /W /°C at 25 - 125 °C. Anisotropic KOH etching of the (100)-oriented silicon substrate was utilized to release the flow sensor microbridge/cantilever microstructures. After designing and building a flow sensor test machine capable of controlled volumetric air flow rates of up to ~15 SLPM (0.54 m/s), nominal sensor sensitivities (SV) of up to 0.67 mV/SLPM (20.4 mV/(m/s)) were measured. The sensitivities varied somewhat depending upon resistor values set in the flow sensor heater-driver circuit and the insertion depth of the devices within the flow channel