Reflective-Physically Unclonable Function based System for Anti-Counterfeiting

Physically unclonable functions (PUF) are physical security mechanisms, which utilize inherent randomness in processes used to instantiate physical objects. In this dissertation, an extensive overview of the state of the art in implementations, accompanying definitions and their analysis is provided. The concept of the reflective-PUF is presented as a product security solution. The viability of the concept, its evaluation and the requirements of such a system is explored

An investigation into the novel application of high power ultrasound on the deinking of mixed office waste paper

The current paper recycling processes are surveyed pointing out the major stages and the variety of chemical/mechanical treatments the fibres undergo. The reduction or replacement of chemical/mechanical treatments presents possible advantages in prolonging fibre life. The results from recycled office waste which has been treated with ultrasound show a change in the particle size distribution of toner particles - making these particles easier to remove using established flotation techniques. Particle size distributions were measured using image analysis on thin (20gsm) paper handsheets. To establish the affect of sonication on fibres, a variety of virgin fibres were obtained from UK Paper, Sittingbourne. Results from virgin fibres which have been treated using ultrasound indicate an absence of cutting compared to conventional techniques. Fibres were found to have the same average length (0.6mm) after ultrasound treatment as the control sample, refined fibres were reduced to approximately 0.3 mm in length. Freeness decreased in both virgin sonicated and refined sonicated samples. The decrease in freeness was accompanied by an increase in the strength properties of both categories of fibres. Experiments with a prepared office waste furnish showed that ultrasonic treatment could decrease the size distribution of fused toner particles. The control sample had an average size of 80.9 um, after 1 minute sonication this was decreased to 54.9) um, decreasing further to 46.8)um after 2 minutes sonication. After demonstrating that ultrasound could decrease the particle distribution of the prepared office waste a more realistic and variable furnish was used. The experiments were conducted at room temperature, 50°C and 75°C. These temperatures were chosen to study the behaviour of fused toners as it approaches and exceeds its glass transition point, essentially the melting point of an amorphous polymer. It was found that the toner is easier to remove as the glass transition temperature is approached. Ultrasound is effective in breaking up large toner particles and detaching particles smaller than 25 microns in diameter

3D printing of sub-micrometer accurate ultra-compact free-form optics

Additive manufacturing enables novel and unprecedented engineering and production possibilities, which are predicted to have an enormous impact in the 21st century. The technology allows for the straightforward three-dimensional printing of volumetric objects as designed. In this thesis, we present a novel concept in optics, which overcomes many difficulties in the fabrication of micro-optics and opens the new field of 3D printed micro- and nano-optics with complex lens designs. Our work is just at the interface between micro- and nano-optics and represents a paradigm shift for micro-optics. It takes only a few hours from lens design, to production, testing, and the final working optical device. Using dip-in femtosecond two-photon direct laser writing, our method goes far beyond state-of-the art attempts to manufacture simple micro-lenses by lithography. We prove the versatility of this method by writing different optics. Collimation optics, toric lenses, free-form surfaces with polynomials of up to 10th order for intensity beam shaping, as well as chiral photonic crystals for circular polarization filtering, all aligned onto the core of single mode fibers are shown. In addition, we show that three-dimensional direct laser writing is a suitable tool for the fabrication of complex multi-lens optical systems that show high quality optical imaging, beam shaping performance, and tremendous compactness with sizes below 300 µm. We determine the accuracy of our optics by analyzing the imaging and beam shaping quality as well as characterizing the surfaces by atomic force microscope measurements and interferometric measurements. The method yields high fabrication accuracy and allows to manufacture of lenses with a rms (root mean square) surface roughness of less than 15 nm. The surfaces deviate from their designs by less than ±1 µm. Our 3D printed compound lenses feature resolving powers of up to 500 line pairs per millimeter. Our printed micro-optical elements can thus achieve sufficient performance in order to enable compound lenses for high quality imaging. In addition, we show the performance of diffractive optical elements with diameters of just 4.4 µm, which enable beam shaping at the end facet of an optical fiber. The intensity is shaped into a uniform or into a donut-shaped intensity distribution. For this purpose, the diffractive optics are directly fabricated onto the end facet of the optical fiber and show unprecedented performance for optical beam shaping. Our method allows for a plethora of novel applications with tremendous impact on optical trapping of atoms and in-vivo imaging in the human body. In addition, applications for imaging and illumination in endoscopy, multiple sensors, and eyes for micro-robots can be realized.Additive Fertigung ermöglicht neuartige und noch nie dagewesene Herstellungs- und Konstruktionsmöglichkeiten, von denen vorhergesagt wird, dass sie einen massiven Einfluss im 21. Jahrhundert haben werden. Die Technologie erlaubt den einfachen dreidimensionalen Druck von massiven Objekten anhand einer Designvorgabe. In dieser Arbeit stellen wir ein innovatives Konzept vor, welches viele Probleme und Schwierigkeiten in der gegenwärtigen Herstellung von Mikrooptiken umgeht und das Feld der 3D gedruckten Mikro- und Nanooptiken eröffnet. Die Optiken können dabei komplexe Linsendesigns aufweisen. Unsere Arbeit ist direkt an der Schnittstelle zwischen Mikro- und Nanooptik und stellt einen Wandel in der Denkweise in der Mikrooptikfabrikation dar. Unsere Herstellungsmethode erlaubt die Fabrikation von Mikrooptiken - vom optischen Designen bis zur Fabrikation - in nur wenigen Stunden. Mit Hilfe von direktem Laserschreiben geht unsere Methode weit über gegenwärtige Herangehensweisen zur Herstellung von einfachen Mikrooptiken hinaus. Wir nutzen dabei Femtosekundenlaserpulse, die mittels nichtlinearem Zwei-Photonen-Absorptionsprozess ein fotosensitives Material gezielt partiell polymerisieren. Anhand der Fabrikation verschiedener Optiken demonstrieren wir die Vielseitigkeit unserer Methode. Insbesondere zeigen wir refraktive optische Elemente, wie Kollimationsoptiken, Zylinderlinsen, torische Linsen und Freiformflächen zur Strahlformung, sowie chirale photonische Kristalle zur Festlegung der Polarisation. Alle optischen Elemente werden dabei auf die Endflächen optischer Glasfasern hergestellt und submikrometergenau relativ zum Faserkern ausgerichtet. Damit wird eine Strahlformung in Intensität und Polarisation direkt an der Endfläche einer Glasfaser erreicht. Zusätzlich zeigen wir, dass das drei-dimensionale, direkte Laserschreiben ebenfalls eine bewährte Möglichkeit zur Herstellung von komplexen Systemen mit mehreren Freiformlinsen ist. Die optischen Systeme weisen dabei eine hohe optische Abbildungsqualität, gute Strahlformungsperformance und eine überlegene Kompaktheit mit Größen unter 300 µm auf. Wir bestimmen die Oberflächengüte und die Fabrikationstoleranzen unserer Optiken durch Analyse der Strahlformungs- und Abbildungsqualität sowie der Charakterisierung anhand von interferometrischen und Rasterkraftmikroskopmessungen. Durch die Verwendung von hochauflösenden Mikroskopobjektiven zur Fokusierung des Schreibstrahls bietet die Herstellungsmethode eine Genauigkeit im Sub-Mikrometerbereich. Dies ermöglicht die Herstellung von Linsensystemen mit Oberflächenrauheiten von weniger als 15 nm (quadratische Rauheit; englisch: root-mean-squared (rms) roughness). Die Oberfläche weicht dabei um weniger als ± 1 µm vom Design ab. Unsere 3D gedruckten Linsensysteme weisen Auflösungsvermögen von bis zu 500 Linienpaaren pro Millimeter auf und erreichen damit eine ausreichende Leistungsfähigkeit um mehrlinsige Systeme für hochqualitative Abbildungen zu realisieren. Ferner zeigen wir die Leistungsfähigkeit von diffraktiven optischen Elementen mit einem Durchmesser von nur 4,4 µm, die es ermöglichen den Lichtstrahl am Ende einer Glasfaser räumlich in eine gleichmäßige oder eine donutförmige Intensitätsverteilung umzuwandeln. Die diffraktiven Optiken werden dazu direkt auf die Endfläche der Glasfaser fabriziert. Unsere Methode erlaubt eine Vielzahl von neuartigen Anwendungen für optische Pinzetten und die in-vivo Bildgebung im menschlichen Körper. Zusätzlich können Anwendungen in der Bildgebung und Beleuchtung für zahlreiche Sensoren, Mikroroboter und die Endoskopie realisiert werden

Array microscopy technology and its application to digital detection of Mycobacterium tuberculosis

Tuberculosis causes more deaths worldwide than any other curable infectious disease. This is the case despite tuberculosis appearing to be on the verge of eradication midway through the last century. Efforts at reversing the spread of tuberculosis have intensified since the early 1990s. Since then, microscopy has been the primary frontline diagnostic. In this dissertation, advances in clinical microscopy towards array microscopy for digital detection of Mycobacterium tuberculosis are presented. Digital array microscopy separates the tasks of microscope operation and pathogen detection and will reduce the specialization needed in order to operate the microscope. Distributing the work and reducing specialization will allow this technology to be deployed at the point of care, taking the front-line diagnostic for tuberculosis from the microscopy center to the community health center. By improving access to microscopy centers, hundreds of thousands of lives can be saved. For this dissertation, a lens was designed that can be manufactured as 4×6 array of microscopes. This lens design is diffraction limited, having less than 0.071 waves of aberration (root mean square) over the entire field of view. A total area imaged onto a full-frame digital image sensor is expected to be 3.94 mm2, which according to tuberculosis microscopy guidelines is more than sufficient for a sensitive diagnosis. The design is tolerant to single point diamond turning manufacturing errors, as found by tolerance analysis and by fabricating a prototype. Diamond micro-milling, a fabrication technique for lens array molds, was applied to plastic plano-concave and plano-convex lens arrays, and found to produce high quality optical surfaces. The micro-milling technique did not prove robust enough to produce bi-convex and meniscus lens arrays in a variety of lens shapes, however, and it required lengthy fabrication times. In order to rapidly prototype new lenses, a new diamond machining technique was developed called 4-axis single point diamond machining. This technique is 2-10x faster than micro-milling, depending on how advanced the micro-milling equipment is. With array microscope fabrication still in development, a single prototype of the lens designed for an array microscope was fabricated using single point diamond turning. The prototype microscope objective was validated in a pre-clinical trial. The prototype was compared with a standard clinical microscope objective in diagnostic tests. High concordance, a Fleiss’s kappa of 0.88, was found between diagnoses made using the prototype and standard microscope objectives and a reference test. With the lens designed and validated and an advanced fabrication process developed, array microscopy technology is advanced to the point where it is feasible to rapidly prototype an array microscope for detection of tuberculosis and translate array microscope from an innovative concept to a device that can save lives

Digital imaging technology assessment: Digital document storage project

An ongoing technical assessment and requirements definition project is examining the potential role of digital imaging technology at NASA's STI facility. The focus is on the basic components of imaging technology in today's marketplace as well as the components anticipated in the near future. Presented is a requirement specification for a prototype project, an initial examination of current image processing at the STI facility, and an initial summary of image processing projects at other sites. Operational imaging systems incorporate scanners, optical storage, high resolution monitors, processing nodes, magnetic storage, jukeboxes, specialized boards, optical character recognition gear, pixel addressable printers, communications, and complex software processes

Development of an image analysis system to produce a standardised assessment of print quality

A method has been developed using an image analysis system that simulates human print quality perception. Previous work in the area of print quality assessment has only produced methods that measure individual print quality variables, or assess small parts of an image. The image analysis system developed in this investigation is different from the previous work because it analyses the combined effects of different variables using neural network technology. In addition, measurements from an entire image can be obtained and the system can assess images irrespective of their shape. The image analysis system hardware consists of a monochrome CCD camera, a Matrox image acquisition board and a 200 MHz Pentium computer. A data pre-processing program was developed using Visual Basic version 5 to process the image data from the camera. The processed data was fed into a neural network so that empirical models of print quality could be formulated. The neural network code originated from the Matlab neural network toolbox. Backpropagation and radial basis neural network functions were used in the investigation. The hardware and software of the image analysis system were tested for non-impact printing techniques. Images of a square, a circle and text characters with dimensions of 1 cm or less were used as test images for the image analysis system. It was established that it was possible to identify the different printing processes that produced the simple shapes and text characters using the image analysis system. This was achieved by training the neural network using pre-processed image data. This produced multi-dimensional mathematical models that were used to classify the different printing processes. The classification of the different printing processes involved the objective measurement of print quality variables. Different printing processes can produce print that differs in print quality when assessed by observers. Therefore the successful classification of the printing processes demonstrated that the image analysis system could, in some cases, simulate human print quality perception. To consolidate on the preceding printing process identification result, a simulation of print quality perception was made. A neural network was trained using observer assessments of a simple pictorial image of a face. These face images were produced using a variety of different non-impact printing techniques. The neural network model was used to predict the outcomes of a further set of assessments of face images by the same observer. The accuracy of the predictions was 23 out of 24 for both the backpropagation and radial basis function neural network functions used in the test. The investigation also produced two possible practical applications for the system. Firstly, it was shown that the system has the potential to be used as a machine that can objectively assess the print quality from photocopiers. Secondly, it was demonstrated that the system might be used for forensic work, since it can identify different printing processes

Latest Advancements in Micro Nano Molding Technologies – Process Developments and Optimization, Materials, Applications, Key Enabling Technologies

Micro- and nano-molding technologies are continuously being developed due to enduring trends like increasing miniaturization and higher functional integration of products, devices, and systems. Furthermore, with the introduction of higher performance polymers, feedstocks, and composites, new opportunities in terms of material properties can be exploited, and, consequently, more micro-products and micro/nano-structured surfaces are currently being designed and manufactured.Innovations in micro- and nano-molding techniques are seen in the different processes employed in production (injection molding, micro injection molding, etc.); on the use of new and functional materials; for an ever-increasing number of applications (health-care devices, micro-implants, mobility, and communications products, optical elements, micro-electromechanical systems, sensors, etc.); in several key enabling technologies that support the successful realization of micro and nano molding processes (micro- and nano-tooling technologies, process monitoring techniques, micro- and nanometrology methods for quality control, simulation, etc.) and their integration into new manufacturing process chains.This Special Issue reprint showcases research papers and review articles that focus on the latest developments in micro-manufacturing and key enabling technologies for the production of both micro-products and micro-structured surfaces

Optical filter simulating foveated vision: modeling and preliminary experiments

This thesis is part of a larger project devoted to understanding, modeling and realizing an optical system inspired by human vision. Precisely, this thesis is aimed at designing an electrically tuneable optical filter based on light scattering (within the visible spectrum) in order to mimic the foveal vision in human eyes. The human vision system is highly dependent on the spatial frequency in sampling, coding, processing and understanding of how physical due to non-uniformity in the distribution of photoreceptors on the retina. The small region, called fovea, has the greatest density of cones (they provide the eye’s colour sensitivity and are active at high light levels, i.e. photopic vision) and such distribution decreases toward the periphery. The rods density distribution is the opposite (they are responsible for vision at very low light levels, i.e. scotopic vision). For this reason, the spatial resolution is not constant across our field of view, but is maximal at the fovea. Our work is aimed at developing an optical filter tuneable, upon an electrically stimulus, and attenuate spatial frequencies before the photodetector sampling. The idea is to have nano-particels with high density in pheriphery and decreasing them in the centre. This phenomenon allows to have a scattering of the light beam in correspondence of the peripheral sensors of a vision system (such as a camera), but not the central ones. So the effective maximal spatial frequency of the input is reduced before sampling. This work is organised in a first experimental part and a second of software simulation. The software simulation has been developed in London in order to use Comsol Multiphysics and CST Studio Suite. The main steps followed are: - Physical realization of different filters with different concentration of nano-particles - Simple scattering analysis by measuring the resolution of images taken in the presence of the filters - Software simulation to validate fundamental principles of scattering and to describe the filter behaviour