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Articles 1 - 20 of 20
Full-Text Articles in Optics
Computational Methods For Propagation Of Optical Fields With The Angle-Impact Wigner Function, Jeremy Wittkopp
Computational Methods For Propagation Of Optical Fields With The Angle-Impact Wigner Function, Jeremy Wittkopp
Legacy Theses & Dissertations (2009 - 2024)
In designing an optical setup for an experiment, one usually turns to simulations first in order to model the propagation of light through the proposed system. This way, the experimenter can determine if the system is operating as intended. In order for these simulations to be useful, they need to properly describe the propagation of light. In order to simplify calculations, most contemporary software makes assumptions on the nature of the light being propagated. Specifically, simulations typically consider optical fields that are beam-like (i.e., most of the rays comprising the field deviate only slightly in angle from the beam's primary …
A Novel Phase And Spectroscopic Imaging Technique To Evaluate Cellular Functions, Ting Chean Khoo
A Novel Phase And Spectroscopic Imaging Technique To Evaluate Cellular Functions, Ting Chean Khoo
Legacy Theses & Dissertations (2009 - 2024)
This thesis presents the application of Raman spectroscopy, digital holographic microscope (DHM) and transport intensity equation (TIE) in imaging biological samples. Raman spectroscopy is a non-destructive technique that can provide chemical structure, concentration, temperature, and molecular interactions. On the other hand, DHM and TIE provide physical measurements such as height, width, area and volume.We applied Raman spectroscopy to study iron-bound transferrin (Tf) in intact human breast cancer cells. Iron is an essential element required for human life and is highly regulated in the body. As the exact mechanisms of iron-bound Tf in cells are not well known, we developed a …
System Measurements For X-Ray Phase And Diffraction Imaging, Erik Wolfgang Tripi
System Measurements For X-Ray Phase And Diffraction Imaging, Erik Wolfgang Tripi
Legacy Theses & Dissertations (2009 - 2024)
In medical imaging, X rays are used to look inside the body to find fractures in bones, abnormal masses, cavities in teeth, and so on. What makes X rays so good at looking at these types of structures is the X ray’s penetration power. When imaging soft tissue to search for tumors, X-ray images tend to have difficulty performing well. The reason for this is that the background structures, such as fat or fibro glandular tissue have similar absorption coefficients as the tumor. Mammography tends to have a high false positive rate and can miss tumors entirely as well. There …
Therapy And Medical Imaging Applications Of Focusing Polycapillary X-Ray Optics, Weiyuan Sun
Therapy And Medical Imaging Applications Of Focusing Polycapillary X-Ray Optics, Weiyuan Sun
Legacy Theses & Dissertations (2009 - 2024)
Focusing polycapillary optics yield high gains in intensity and increased spatial resolution for a variety of clinical, lab-based, synchrotron, or in situ analysis applications. In this dissertation we investigate the extension of two applications of focusing polycapillary optics. The first is the application of polycapillary optics in radiation therapy. This discussion includes measurements and calculation of dose for focused beam orthovoltage therapy. A system has been designed to investigate whether the polycapillary optics can produce an X-ray beam which can give more accurate dose painting due to the higher dose concentration at the focal spot. X-ray exposures were measured with …
Illumination Modulation For Improved Propagation-Based Phase Imaging, Tonmoy Chakraborty
Illumination Modulation For Improved Propagation-Based Phase Imaging, Tonmoy Chakraborty
Legacy Theses & Dissertations (2009 - 2024)
Propagation-based phase imaging enables the quantitative reconstruction of a light beam's phase from measurements of its intensity. Because the intensity depends on the time-averaged square of the field the relationship between intensity and phase is, in general, nonlinear. The transport of intensity equation (TIE), is a linear equation relating phase and propagated intensity that arises from restricting the propagation distance to be small. However, the TIE limits the spatial frequencies that can be reliably reconstructed to those below some cutoff, which limits the accuracy of reconstruction of fine features in phase. On the other hand, the low frequency components suffer …
Photonic Grating Coupler Designs For Optical Benching, Eng Wen Ong
Photonic Grating Coupler Designs For Optical Benching, Eng Wen Ong
Legacy Theses & Dissertations (2009 - 2024)
Background: Silicon Photonics has been rapidly developing as a field. The primary reason for this is its lower operating costs and faster switching rates for use in big data centres. Instead of microns-wide copper lines to transmit signals, silicon photonic chips use waveguides, usually of silicon or silicon nitride. Photonic signals bypass the issues of resistive-capacitance lag (RC-lag) and resistive-heating encountered by copper lines. Additionally, a single waveguide may transmit multiple signals along different carrier wavelengths.
Optical Metrology For Directed Self-Assembly Patterning Using Mueller Matrix Spectroscopic Ellipsometry Based Scatterometry, Dhairya J. Dixit
Optical Metrology For Directed Self-Assembly Patterning Using Mueller Matrix Spectroscopic Ellipsometry Based Scatterometry, Dhairya J. Dixit
Legacy Theses & Dissertations (2009 - 2024)
The semiconductor industry continues to drive patterning solutions that enable devices with higher memory storage capacity, faster computing performance, lower cost per transistors, and higher transistor density. These developments in the field of semiconductor manufacturing along with the overall minimization of the size of transistors require cutting-edge metrology tools for characterization.
Phase Imaging Using X-Ray Optics, Bushra Kanwal
Phase Imaging Using X-Ray Optics, Bushra Kanwal
Legacy Theses & Dissertations (2009 - 2024)
Conventional x-ray imaging is a widely used imaging technique in medical diagnostics as well as material analysis. It utilizes only absorption-contrast imaging, which records intensity attenuation due to absorption. A major limitation of this technique for medical imaging is the poor contrast of weakly absorbing details in the soft tissue. Mammography and angiography are two examples where improved contrast is required. In the quest for better contrast in x-ray imaging, a number of different phase contrast imaging techniques have been explored. Phase contrast imaging offers an improvement over traditional absorption contrast because the x-ray wave field traversing an object experiences …
An Assessment Of Critical Dimension Small Angle X-Ray Scattering Metrology For Advanced Semiconductor Manufacturing, Charles Michael Settens
An Assessment Of Critical Dimension Small Angle X-Ray Scattering Metrology For Advanced Semiconductor Manufacturing, Charles Michael Settens
Legacy Theses & Dissertations (2009 - 2024)
Simultaneous migration of planar transistors to FinFET architectures, the introduction of a plurality of materials to ensure suitable electrical characteristics, and the establishment of reliable multiple patterning lithography schemes to pattern sub-10 nm feature sizes imposes formidable challenges to current in-line dimensional metrologies. Because the shape of a FinFET channel cross-section immediately influences the electrical characteristics, the evaluation of 3D device structures requires measurement of parameters beyond traditional critical dimension (CD), including their sidewall angles, top corner rounding and footing, roughness, recesses and undercuts at single nanometer dimensions; thus, metrologies require sub-nm and approaching atomic level measurement uncertainty.
Experimental And Simulation Studies Of Printability Of Buried Euv Mask Defects And Study Of Euv Reflectivity Loss Mechanisms Due To Standard Euv Mask Cleaning Processes, Mihirkant Upadhyaya
Experimental And Simulation Studies Of Printability Of Buried Euv Mask Defects And Study Of Euv Reflectivity Loss Mechanisms Due To Standard Euv Mask Cleaning Processes, Mihirkant Upadhyaya
Legacy Theses & Dissertations (2009 - 2024)
There's a big push for development and commercialization of extreme ultraviolet (EUV) lithography for high-volume semiconductor manufacturing of 14 nm half-pitch patterning and beyond. One of the primary concerns for making this a reality has been the ability to achieve defect-free masks. My study is focused on two aspects related to the performance degradation of the EUV masks namely EUV mask cleaning induced reflectivity loss mechanisms, and the buried multilayer phase defects in EUV masks.
Diffraction-Based Techniques For High Contrast X-Ray Imaging, Lubna Naseem Peerzada
Diffraction-Based Techniques For High Contrast X-Ray Imaging, Lubna Naseem Peerzada
Legacy Theses & Dissertations (2009 - 2024)
Two X-ray diffraction based techniques for high contrast were explored to improve contrast in radiology: diffraction enhanced imaging (DEI) and coherent scatter imaging.
Modeling A Sensor To Improve Its Efficacy, Nabin K. Malakar, Daniil Gladkov, Kevin H. Knuth
Modeling A Sensor To Improve Its Efficacy, Nabin K. Malakar, Daniil Gladkov, Kevin H. Knuth
Physics Faculty Scholarship
Robots rely on sensors to provide them with information about their surroundings. However, high-quality sensors can be extremely expensive and cost-prohibitive. Thus many robotic systems must make due with lower-quality sensors. Here we demonstrate via a case study how modeling a sensor can improve its efficacy when employed within a Bayesian inferential framework. As a test bed we employ a robotic arm that is designed to autonomously take its own measurements using an inexpensive LEGO light sensor to estimate the position and radius of a white circle on a black field. The light sensor integrates the light arriving from a …
Surface Plasmonic Lens Driven Photoelectron Source For Multi-Beam Applications, Heon Joon Choi
Surface Plasmonic Lens Driven Photoelectron Source For Multi-Beam Applications, Heon Joon Choi
Legacy Theses & Dissertations (2009 - 2024)
Surface plasmon polariton (SPP) assisted photoelectron source array is proposed for use in distributed multiple electron beam lithography applications. Individual source is composed of a metal/dielectric surface structure with concentric circular grooves of subwavelength width surrounding a sub-wavelength aperture. Such optical power concentrators, called "plasmonic lenses", collect light incident over a broad area by converting it to surface electromagnetic waves, specifically SPP's, through diffraction by the sub-wavelength grooves surrounding the aperture. Through constructive interference of the generated SPPs between neighboring grooves, controlled by the periodicity of the grooves, high optical power densities can be achieved at the center of the …
Potential For High Resolution Microscintigraphy Using Polycapillary Optics, Patrick Richard Conlon
Potential For High Resolution Microscintigraphy Using Polycapillary Optics, Patrick Richard Conlon
Legacy Theses & Dissertations (2009 - 2024)
Scintigraphy, also known as nuclear imaging, is the process of imaging an object that has been labeled with a radioactive material. A novel technique employing polycapillary optics for very high - resolution scintigraphy is presented. The small channel size and angular selectivity of polycapillary optics allow them to act as multiple-hole collimators and be used with high - resolution detectors. The ability of the optics to work with high resolution detectors allow the system to discriminate against scatter, thus negating the need for energy sensitive detectors, which are known to have poor resolution. Therefore the use of polycapillary optics presents …
Mueller Based Scatterometry And Optical Characterization Of Semiconductor Materials, Gangadhara Raja Muthinti
Mueller Based Scatterometry And Optical Characterization Of Semiconductor Materials, Gangadhara Raja Muthinti
Legacy Theses & Dissertations (2009 - 2024)
Scatterometry is one of the most useful metrology methods for the characterization and control of critical dimensions (CD) and the detailed topography of periodic structures found in microelectronics fabrication processes. Spectroscopic ellipsometry (SE) and normal incidence reflectometry (NI) based scatterometry are the most widely used optical methodologies for metrology of these structures. Evolution of better optical hardware and faster computing capabilities led to the development of Mueller Matrix (MM) based Scatterometry (MMS). Dimensional metrology using full Mueller Matrix (16 element) scatterometry in the wavelength range of 245nm-1000nm was discussed in this work. Unlike SE and NI, MM data provides complete …
Simulation Of Polycapillary And Multichannel Plate X-Ray Optics, Robert Schmitz
Simulation Of Polycapillary And Multichannel Plate X-Ray Optics, Robert Schmitz
Legacy Theses & Dissertations (2009 - 2024)
Simulation of x-ray optical systems is an important tool for optics design for known applications, and optic development for potential applications. Polycapillary optics are thin glass cylinders containing hundreds of thousands of hollow channels that transmit x rays using total external reflection. These optics have been developed for many applications, from beam filtering to x-ray collimating or focusing. A Monte Carlo based ray-tracing simulation was developed to model a wide range of polycapillary optic geometries. The simulation uses a vector-based approach to model all photons and optical geometries in three dimensions. Simulation verification was performed for a wide range of …
Electron Beam Lithography Throughput And Resolution Enhancement With Innovative Blanker Design, Junru Ruan
Electron Beam Lithography Throughput And Resolution Enhancement With Innovative Blanker Design, Junru Ruan
Legacy Theses & Dissertations (2009 - 2024)
Electron Beam Lithography (EBL) is one of the most important and most widely used methods for nano-fabrication. The primary advantage of electron beam lithography is its high resolution, and its ability to expose nanometer features without a mask. On the other hand, one of the key limitations of electron beam lithography is throughput. Slow blanking speed is one of the major bottlenecks for the system speed. In this dissertation, I will first review the prior literature of high speed blanking. Thorough theoretical and experimental studies are done on the existing designs. Physical models are built and analytical ray tracing is …
Application Of X-Ray Diffraction To Material Analysis And Medical Imaging, Wei Zhou
Application Of X-Ray Diffraction To Material Analysis And Medical Imaging, Wei Zhou
Legacy Theses & Dissertations (2009 - 2024)
Powder diffraction is commonly used to determine the structures of both inorganic and organic materials. The angle and intensity of the diffraction (also called coherent scatter) peak depends on the nanostructure of the material. When no x-ray optic is used, the peak width broadens, and hence the resolution worsens, as the sample area is increased. However, a small sample area gives low diffracted signal intensity, particularly for thin films and for organic materials, which have low diffraction cross sections. X-ray optics can be used in x-ray powder diffraction to increase the diffraction intensity, thus decreasing exposure times. For a small …
Nanocomposite Thin Films Of Au Nanoparticles Embedded In Yttria-Stabilized Zirconia For Plasmonic-Based Harsh Environment Gas Detection, Phillip Henry Rogers
Nanocomposite Thin Films Of Au Nanoparticles Embedded In Yttria-Stabilized Zirconia For Plasmonic-Based Harsh Environment Gas Detection, Phillip Henry Rogers
Legacy Theses & Dissertations (2009 - 2024)
Increased health concerns due to the emission of gases linked to the production of tropospheric ozone by petroleum based fuel burning engines has resulted in the codification of more stringent emissions regulations domestically. Emissions regulations on commercial jetliners are one of the areas to be met with stricter standards. Currently there is not a sensing technology that can detect the emissions gases in the exhaust stream of a jet turbine engine with lower detection limits that meet these standards.
Doubly Curved Crystal Optics For Monochromatic And Diffraction Enhanced X-Ray Imaging, Santosh Kumar Sahoo
Doubly Curved Crystal Optics For Monochromatic And Diffraction Enhanced X-Ray Imaging, Santosh Kumar Sahoo
Legacy Theses & Dissertations (2009 - 2024)
In radiographic imaging the contrast can be enhanced with the use of monochromatic radiation compared to conventional broadband source. Monochromatic beam radiation can be produced with conventional sources by diffraction off of flat monochromator crystals, but this produces a low monochromatic intensity for imaging.