Optimization of the holographic process for imaging and lithography

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 272-297).Since their invention in 1948 by Dennis Gabor, holograms have demonstrated to be important components of a variety of optical systems and their implementation in new fields and methods is expected to continue growing. Their ability to encode 3D optical fields on a 2D plane opened the possibility of novel applications for imaging and lithography. In the traditional form, holograms are produced by the interference of a reference and object waves recording the phase and amplitude of the complex field. The holographic process has been extended to include different recording materials and methods. The increasing demand for holographic-based systems is followed by a need for efficient optimization tools designed for maximizing the performance of the optical system. In this thesis, a variety of multi-domain optimization tools designed to improve the performance of holographic optical systems are proposed. These tools are designed to be robust, computationally efficient and sufficiently general to be applied when designing various holographic systems. All the major forms of holographic elements are studied: computer generated holograms, thin and thick conventional holograms, numerically simulated holograms and digital holograms. Novel holographic optical systems for imaging and lithography are proposed. In the case of lithography, a high-resolution system based on Fresnel domain computer generated holograms (CGHs) is presented. The holograms are numerically designed using a reduced complexity hybrid optimization algorithm (HOA) based on genetic algorithms (GAs) and the modified error reduction (MER) method. The algorithm is efficiently implemented on a graphic processing unit. Simulations as well as experimental results for CGHs fabricated using electron-beam lithography are presented. A method for extending the system's depth of focus is proposed. The HOA is extended for the design and optimization of multispectral CGHs applied for high efficiency solar concentration and spectral splitting. A second lithographic system based on optically recorded total internal reflection (TIR) holograms is studied. A comparative analysis between scalar and (cont.) vector diffraction theories for the modeling and simulation of the system is performed.A complete numerical model of the system is conducted including the photoresist response and first order models for shrinkage of the holographic emulsion. A novel block-stitching algorithm is introduced for the calculation of large diffraction patterns that allows overcoming current computational limitations of memory and processing time. The numerical model is implemented for optimizing the system's performance as well as redesigning the mask to account for potential fabrication errors. The simulation results are compared to experimentally measured data. In the case of imaging, a segmented aperture thin imager based on holographically corrected gradient index lenses (GRIN) is proposed. The compound system is constrained to a maximum thickness of 5mm and utilizes an optically recorded hologram for correcting high-order optical aberrations of the GRIN lens array. The imager is analyzed using system and information theories. A multi-domain optimization approach is implemented based on GAs for maximizing the system's channel capacity and hence improving the information extraction or encoding process. A decoding or reconstruction strategy is implemented using the superresolution algorithm. Experimental results for the optimization of the hologram's recording process and the tomographic measurement of the system's space-variant point spread function are presented. A second imaging system for the measurement of complex fluid flows by tracking micron sized particles using digital holography is studied. A stochastic theoretical model based on a stability metric similar to the channel capacity for a Gaussian channel is presented and used to optimize the system. The theoretical model is first derived for the extreme case of point source particles using Rayleigh scattering and scalar diffraction theory formulations. The model is then extended to account for particles of variable sizes using Mie theory for the scattering of homogeneous dielectric spherical particles. The influence and statistics of the particle density dependent cross-talk noise are studied. Simulation and experimental results for finding the optimum particle density based on the stability metric are presented. For all the studied systems, a sensitivity analysis is performed to predict and assist in the correction of potential fabrication or calibration errors.by José Antonio Domínguez-Caballero.Ph.D

Aeronomy report no. 74: The Urbana meteor-radar system; design, development, and first observations

The design, development, and first observations of a high power meteor-radar system located near Urbana, Illinois are described. The roughly five-fold increase in usable echo rate compared to other facilities, along with automated digital data processing and interferometry measurement of echo arrival angles, permits unsurpassed observations of tidal structure and shorter period waves. Such observations are discussed. The technique of using echo decay rates to infer density and scale height and the method of inferring wind shear from radial acceleration are examined. An original experiment to test a theory of the Delta-region winter anomaly is presented

Journal of Air Transportation, Volume 11, No. 2

The following topics were covered: How Do Airlines Perceive That Strategic Alliances Affect Their Individual Branding?; Airline Choice for Domestic Flights in Sao Paulo Metropolitan Area: An Application of the Conditional Logit Model; Consequences of Feeder Delays for the Success of A380 Operations; Inside the Mechanics of Network Development: How Competition and Strategy Reorganize European Air Traffic; The Opportunities and Threats of Turning Airports into Hubs; Another Approach to Enhance Airline Safety: Using System Safety Tools; A Simulation Based Approach for Contingency Planning for Aircraft Turnaround Activities in Airline Hubs; and The Council on Aviation Accreditation: Part One- Historical Foundation

Frameshift mutations at the C-terminus of HIST1H1E result in a specific DNA hypomethylation signature

BACKGROUND: We previously associated HIST1H1E mutations causing Rahman syndrome with a specific genome-wide methylation pattern. RESULTS: Methylome analysis from peripheral blood samples of six affected subjects led us to identify a specific hypomethylated profile. This "episignature" was enriched for genes involved in neuronal system development and function. A computational classifier yielded full sensitivity and specificity in detecting subjects with Rahman syndrome. Applying this model to a cohort of undiagnosed probands allowed us to reach diagnosis in one subject. CONCLUSIONS: We demonstrate an epigenetic signature in subjects with Rahman syndrome that can be used to reach molecular diagnosis

Image Registration Workshop Proceedings

Automatic image registration has often been considered as a preliminary step for higher-level processing, such as object recognition or data fusion. But with the unprecedented amounts of data which are being and will continue to be generated by newly developed sensors, the very topic of automatic image registration has become and important research topic. This workshop presents a collection of very high quality work which has been grouped in four main areas: (1) theoretical aspects of image registration; (2) applications to satellite imagery; (3) applications to medical imagery; and (4) image registration for computer vision research

A braided quasi quantum group from strings in a magnetic field : two applications of noncommutative geometry

The operators that realize a discrete symmetry group on a physical system describing a particle in a magnetic field furnish a projective representation of the group on the particle states. Promoting the magnetic background to a topologically non trivial field, one can still derive the magnetic translation operators from the path integral approach in their general form. For that, one has to introduce some basic differential geometrical techniques, for example the concept of a complex line bundle with connection, the wave functions seen as sections thereof as well as holonomies along trajectories. It is interesting to ask whether such a construction can be extended to the case of a propagating string, making use of similar geometrical techniques. In the higher dimensional string case, the magnetic field is a 3-form, the so called Kalb-Ramond field strength. To derive the operators that lift the group action to the states, one has to construct the magnetic amplitudes in terms of the locally given fields. Once constructed, the translation operators turn out to generate a braided quasi quantum group which is the twisted version of the Drinfel'd quantum double of a finite group algebra. The 3-cocycle providing the twist is related to the Kalb-Ramond field by a series of de Rham, Cech and group cohomological equations finding their natural framework in a tricomplex. As a Hopf algebra, the algebra generated by the magnetic translations comes equipped with some algebraic ingredients, that find their physical counterpart in operations on magnetic amplitudes. For example, the coproduct provides the representation of a string interaction process given by a world-sheet having the shape of a pair of pants. A braided Hopf algebra allows for a representation of the braid group on the tensor category of its modules, which becomes as such a braided monoidal category. This allows to identify the Hilbert spaces of string states with objects of the category. It is rather amazing that such a non-trivial algebraic structure pops up almost automatically by the requirement of gauge invariance and the commutation of translations with propagation

Array comparative genomic hybridisation and the newborn intensive care unit: Sociological perspectives on mainstreaming medical genetics

This thesis presents the findings of a UK-based ethnography of the mainstreaming of array comparative genomic hybridisation in the neonatal intensive care unit. Mainstreaming refers to the strategies employed to embed genetic/genomic technologies for patient benefit, incorporating genome-wide methods in everyday, mundane clinical work, beyond the specialist genetic realm. It draws on observations in the laboratory and the clinic alongside interviews with members of the extended bioclinical collective (Bourett, 2005). This constructs an ethnography of the activity of doing chromosomal microarray (Mol, 2002). I describe how three important traditions in sociological thought – namely (medical) uncertainty, processes of classification and categorisation and expertise – can be applied to the activity of mainstreaming. In the laboratory, I explore the role of standardisation and how despite calls for rigid adherence to technical rules, it is the subversion of standards – through appeals to expertise – that renders the technology workable for the messy clinical context. I continue by describing the dividing practices of the clinic, which designate infants as (potentially) genetically problematic, demonstrating how discourses between professionals and with parents serve to seek the assent of parents for chromosomal microarray testing through a highly directive process. I show how rhetorical discourse devices are using in ‘consent conversations’ as a tool in information sharing and as a means of persuasion. For the parents of infants having aCGH testing, uncertainty around decisions to test and the information genetic testing can generate are woven into personal narratives of restitution, chaos and quest (Frank,1995). I conclude by reflecting upon how the ability and means by which uncertainty is tolerated differs vastly between the laboratory, the clinic and the family and the way in which diverging practices enact ontology in medicine as bound to specific sites and situations (Mol, 2002)

Optical In-Process Measurement Systems

Information is key, which means that measurements are key. For this reason, this book provides unique insight into state-of-the-art research works regarding optical measurement systems. Optical systems are fast and precise, and the ongoing challenge is to enable optical principles for in-process measurements. Presented within this book is a selection of promising optical measurement approaches for real-world applications