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2020

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Articles 91 - 120 of 140

Full-Text Articles in Optics

Holographic Security, Vincent Toal Jan 2020

Holographic Security, Vincent Toal

Books/Book Chapters

This chapter is concerned with the security applications of holographic techniques. Holograms are used in product authentication, product branding and brand protection, and personal and other documents. Serialization to ensure the uniqueness of each hologram for added security is briefly discussed. The theory of optical character recognition and joint transform correlation methods is outlined. Holographic recording using encrypted reference waves enables secure storage of information. Several methods are considered for encrypting optical data as well as holographic recording of encrypted images and their reconstruction and decryption. Millimeter and microwave holographic imaging techniques for the detection of hidden contraband, narcotics, firearms, …

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Thermodynamic Theory Of Heavily Multimoded Nonlinear Optical Systems, Fan Wu Jan 2020

Thermodynamic Theory Of Heavily Multimoded Nonlinear Optical Systems, Fan Wu

Electronic Theses and Dissertations, 2020-2023

The quest for ever higher information capacities has brought about a renaissance in multimode optical waveguide systems. This resurgence of interest has recently initiated a flurry of activities in nonlinear multimode fiber optics. The sheer complexity emerging from the presence of a multitude of nonlinearly interacting modes has led not only to new opportunities in observing a host of novel optical effects that are otherwise impossible in single-mode settings, but also to new theoretical challenges in understanding their collective dynamics. In this dissertation, we present a consistent thermodynamical framework capable of describing in a universal fashion the exceedingly intricate behavior …

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Novel Fibers And Components For Space Division Multiplexing Technologies, Juan Carlos Alvarado Zacarias Jan 2020

Novel Fibers And Components For Space Division Multiplexing Technologies, Juan Carlos Alvarado Zacarias

Electronic Theses and Dissertations, 2020-2023

Passive devices and amplifiers for space division multiplexing are key components for future deployment of this technology and for the development of new applications exploring the spatial diversity of light. Some important devices include photonic lantern (PL) mode multiplexers supporting several modes, fan-in/fan-out (FIFO) devices for multicore fibers (MCFs), and multimode amplifiers capable of amplifying several modes with low differential modal gain penalty. All these components are required to overcome the capacity limit of single mode fiber (SMF) communication systems, driven by the growing data capacity demand. In this dissertation I propose and develop different passive components and amplifiers for …

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Optimisation Of The Performance Of Holographic Beam-Shaping Diffractive Diffusers Through Refinement Of The Recording Process, Cara Jones, Suzanne Martin, Sanjay Keshri, Dervil Cody, Kevin Murphy Jan 2020

Optimisation Of The Performance Of Holographic Beam-Shaping Diffractive Diffusers Through Refinement Of The Recording Process, Cara Jones, Suzanne Martin, Sanjay Keshri, Dervil Cody, Kevin Murphy

Conference Papers

Optical diffusers have uses in laser applications and machine vision. Typical fabrication at a commercial level requires master production and the stamping/copying of individual elements at scale. This expensive, indirect process inhibits custom diffusers at reasonable cost. Previously the authors published a novel, direct, single beam method of recording customizable and controllable volume holographic diffusers by manipulating laser speckle and recording the pattern in photopolymer. This method allows for beam-shaping to produce diffusion patterns of various sizes and shapes. In this work, the direct method of recording controllable holographic diffusers is refined to improve diffuser performance (i.e., a decrease in …

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Corrections To ‘‘Glaciernet: A Deep-Learning Approach For Debris-Covered Glacier Mapping’’, Zhiyuan Xie, Umesh K. Haritashya, Vijayan K. Asari, Brennan W. Young, Michael P. Bishop, Jeffrey S. Kargel Jan 2020

Corrections To ‘‘Glaciernet: A Deep-Learning Approach For Debris-Covered Glacier Mapping’’, Zhiyuan Xie, Umesh K. Haritashya, Vijayan K. Asari, Brennan W. Young, Michael P. Bishop, Jeffrey S. Kargel

Electrical and Computer Engineering Faculty Publications

In the above article [1], Figure 2 was incorrect. Unfortunately, we mixed the color label of "CONV $\to $ BN $\to $ ReLu" and "Unpooling" in the CNN structure section of Figure 2. The color label of "CONV $\to $ BN $\to $ ReLu" should be orange while the color label of "Unpooling" should be green. Also, the word "Decoder" is misspelled. That same figure with the same error is also used for the graphic abstract. The corrected figure is given here. None of the sections in the figure is modified. The only change is in the color label of …

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Wave-Optics Simulation Of Correlated Speckle Fields, Derek Burrell Jan 2020

Wave-Optics Simulation Of Correlated Speckle Fields, Derek Burrell

Electronic Theses and Dissertations, 2020-2023

Laser speckle poses an ongoing challenge to optical systems that utilize coherent light for active illumination, including applications in holography, free-space communications, remote sensing and target tracking. Speckle averaging offers one potential path forward by reducing the contrast, thereby boosting signal-to-noise ratios. This approach becomes limited, however, by the degree of correlation between successive frames. Wave-optics simulations help to characterize performance gains through speckle averaging, and so it is important that existing models properly account for decorrelation rates of dynamic speckle. With that goal in mind, this research seeks to build a suite of computational wave-optics experiments that verify speckle …

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Development Of High-Power Single-Mode Yb-Doped Fiber Amplifiers And Beam Analysis, Steffen Wittek Jan 2020

Development Of High-Power Single-Mode Yb-Doped Fiber Amplifiers And Beam Analysis, Steffen Wittek

Electronic Theses and Dissertations, 2020-2023

High-power fiber laser systems enjoy a widespread use in manufacturing, medical, and defense applications as well as scientific research, due to their remarkable power scalability, high electrical to optical efficiency, compactness and ruggedness. However, single-mode fiber power scaling has stagnated in the past years, primarily due to the onset of nonlinear effects such as stimulated Brillouin/Raman scattering and transverse modal instabilities. This thesis addresses the analysis and mitigation of transverse modal instabilities in high-power fiber amplifiers. I describe the high-power fiber amplifier testbed that I set up to test fibers fabricated in house. I will show our results of a …

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Attosecond Transient Absorption Spectroscopy In The Water Window, Andrew Chew Jan 2020

Attosecond Transient Absorption Spectroscopy In The Water Window, Andrew Chew

Electronic Theses and Dissertations, 2020-2023

The push to study the atomic and molecular dynamics at ever smaller time scales has been the main driving force for developing laser systems with ever shorter pulse durations. Thus far, picosecond lasers and femtosecond lasers have been used with great success in femtochemistry to study molecular dynamics such as molecular rotation and vibration, which all occur in the tens to hundreds of femtosecond. To study electron dynamics however, which are on the order of attoseconds, one needs attosecond laser sources to be able to have the time resolution required to probe ultrafast electron dynamics such as AC Stark shifts, …

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Microfluidic Flow Direction And Rate Vector Sensor Based On A Partially Gold-Coated Tfbg, Changyu Shen, Dejun Liu, Xiaokang Lian, Tingting Lang, Chunliu Zhao, Yuliya Semenova, Jacques Albert Jan 2020

Microfluidic Flow Direction And Rate Vector Sensor Based On A Partially Gold-Coated Tfbg, Changyu Shen, Dejun Liu, Xiaokang Lian, Tingting Lang, Chunliu Zhao, Yuliya Semenova, Jacques Albert

Articles

In microfluidic chips applications, the monitoring of the rate and the direction of a microfluidic flow is very important. Here, we demonstrate a liquid flow rate and a direction sensor using a partially gold-coated tilted fiber Bragg grating (TFBG) as the sensing element. Wavelength shifts and amplitude changes of the TFBG transmission resonances in the near infrared reveal the direction of the liquid flowing along the fiber axis in the vicinity of the TFBG due to a nanoscale gold layer over part of the TFBG. For a device length of 10 mm (and a diameter of 125 µm for easy …

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Simultaneous Measurement Of Displacement And Temperature Based On Two Cascaded Balloon-Like Bent Fibre Structures, Ke Tian, Ruoning Wang, Meng Zhang, Xiafan Wang, Xin Wang, Guoyong Jin, Elfed Lewis, Gerald Farrell, Pengfei Wang Jan 2020

Simultaneous Measurement Of Displacement And Temperature Based On Two Cascaded Balloon-Like Bent Fibre Structures, Ke Tian, Ruoning Wang, Meng Zhang, Xiafan Wang, Xin Wang, Guoyong Jin, Elfed Lewis, Gerald Farrell, Pengfei Wang

Articles

A low-cost optical fibre sensor based on two cascaded balloon-like bent fibre (BBF) structures for simultaneous displacement and temperature measurement is reported. The sensor is fabricated by cascading two balloon-like bent single-mode fibres (SMFs) which with different bending radii, generating two separate interference dips within a limited wavelength range. The wavelength of the two interference dips exhibits different responses to external displacement and temperature variations, hence simultaneous measurement of displacement and temperature is realized. Experimental results show that the proposed optical fibre sensor achieves a displacement sensitivity of −318.8 pm/μm and a temperature sensitivity of 47.4 pm/°C. Taking advantage of …

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High-Sensitivity Temperature Sensor Based On Anti-Resonance In High-Index Polymer-Coated Optical Fiber Interferometers, Xiaokang Lian, Qiang Wu, Gerald Farrell, Yuliya Semenova Jan 2020

High-Sensitivity Temperature Sensor Based On Anti-Resonance In High-Index Polymer-Coated Optical Fiber Interferometers, Xiaokang Lian, Qiang Wu, Gerald Farrell, Yuliya Semenova

Articles

Compared to the multimode interference (MMI) effect, the anti-resonance (AR) effect does not rely on the multimode property of the optical waveguide. This Letter shows that fiber bending can suppress the MMI and can break the superposition of AR spectra of multiple modes in a high-index polymer-coated optical fiber interferometer based on a single-mode fiber-polymer-coated no-core fiber-single-mode fiber hetero-structure. This results in the dominance of the AR spectrum of an individual mode and consequently in periodic sharp transmission dips. As a result of this phenomenon and large thermo-optical and thermal expansion coefficients of the polymer, a compact, high-sensitivity and linear …

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Collision Of Li2+ With Li(2s) And Li(2p): Differential And Total Ionization; Discrete Excitations; Elastic Scattering, And Total Cross Section, H.R.J. Walters, Colm T. Whelan Jan 2020

Collision Of Li2+ With Li(2s) And Li(2p): Differential And Total Ionization; Discrete Excitations; Elastic Scattering, And Total Cross Section, H.R.J. Walters, Colm T. Whelan

Physics Faculty Publications

The coupled pseudostate approximation (McGovern et al 2009 Phys. Rev. A 79 042707) has been applied to Li2+ + Li(2s, 2p0,±1) collisions at 16 MeV with emphasis on studying the fully differential ionization measurements of Ghanbari-Adivi et al in the azimuthal plane (2017 J. Phys. B: At. Mol. Opt. Phys. 50 215202). The states of the valence electron in the Li target are calculated using the model potential of Stein (1993 J. Phys. B: At. Mol. Opt. Phys. 26 2087). Altogether 164 states with angular momenta l = 0 to 9 are employed in …

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Microspheres With Atomic-Scale Tolerances Generate Hyperdegeneracy, Jacob Kher-Alden, Shai Maayani, Leopoldo L. Martin, Mark Douvidzon, Lev Deych, Tal Carmon Jan 2020

Microspheres With Atomic-Scale Tolerances Generate Hyperdegeneracy, Jacob Kher-Alden, Shai Maayani, Leopoldo L. Martin, Mark Douvidzon, Lev Deych, Tal Carmon

Publications and Research

Degeneracies play a crucial rule in precise scientific measurements as well as in sensing applications. Spherical resonators have a high degree of degeneracy thanks to their highest symmetry; yet, fabricating perfect spheres is challenging because even a stem to hold the sphere breaks the symmetry. Here we fabricate a levitating spherical resonator that is evanescently coupled to a standard optical fiber. We characterize the resonators to exhibit an optical quality factor exceeding a billion, 10 μm radius, and sphericity to within less than 1µ. Using our high quality and sphericity, we experimentally lift degeneracies of orders higher than 200, which …

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Heterogeneous Integrated Photonics For Nonlinear Frequency Conversion And Polarization Diversity, Tracy Sjaardema Jan 2020

Heterogeneous Integrated Photonics For Nonlinear Frequency Conversion And Polarization Diversity, Tracy Sjaardema

Electronic Theses and Dissertations, 2020-2023

Silicon has proven to be one of the materials of choice for many integrated photonic applications. However, silicon photonics is limited by certain material shortcomings. Two shortcomings addressed in this work are zero second-order optical nonlinearity, and the lack of methods available to achieve broadband polarization diversity. Heterogeneous integrated solutions for these shortcomings of silicon photonics are presented in this work. First, nonlinear frequency conversion is demonstrated with thin-film lithium niobate on silicon substrates. The method for reaching the highest-achieved second-harmonic generation conversion efficiency, using active monitoring during periodic poling, is discussed. Additionally, a cascaded approach for generating higher-order harmonics …

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Few-Mode Fiber Lasers And Amplifiers, Ning Wang Jan 2020

Few-Mode Fiber Lasers And Amplifiers, Ning Wang

Electronic Theses and Dissertations, 2020-2023

Lasers and amplifiers of high-order spatial modes are useful for a number of applications, including communication, sensing, microscopy, and laser material processing. This dissertation presents the generation and amplification of high-order spatial modes in few-mode fibers (FMFs). In the area of amplification of high-order spatial modes, low-crosstalk amplification among spatial modes is realized in a retro-reflecting few-mode Er-doped fiber amplifier (EDFA) by exploiting the unitary property of the coupling matrix of a symmetric photonic lantern (PL). A small-signal gain larger than 25 dB and crosstalk below -10 dB was achieved over the C-band for a 3-mode EDFA. Such a few-mode …

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Twisted Space-Frequency And Space-Time Partially Coherent Beams, Milo W. Hyde Iv Jan 2020

Twisted Space-Frequency And Space-Time Partially Coherent Beams, Milo W. Hyde Iv

Faculty Publications

We present partially coherent sources that are statistically twisted in the space-frequency and space-time domains. Beginning with the superposition rule for genuine partially coherent sources, we derive source plane expressions for the cross-spectral density (CSD) and mutual coherence functions (MCFs) for twisted space-frequency and space-time Gaussian Schell-model (GSM) beams. Using the Fresnel approximation to the free-space Green’s function, we then paraxially propagate the CSD and MCF to any plane z> 0. We discuss the beams’ behavior as they propagate, with particular emphasis on how the beam shape rotates or tumbles versus z. To validate our analysis, we simulate the generation …

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Modification Of The Optical Response Of Alpha Quartz Via The Deposition Of Gold Nanoparticles In Etched Ion Tracks, Maria C. Garcia Toro Jan 2020

Modification Of The Optical Response Of Alpha Quartz Via The Deposition Of Gold Nanoparticles In Etched Ion Tracks, Maria C. Garcia Toro

Doctoral Dissertations

”This study addresses the experimental methods used to develop and characterize plasmonic devices capable of modifying the optical response of alpha quartz via the deposition of gold nanoparticles in etched ion tracks. In the first part of the research, the microstructural characterization of latent and etched ion tracks produced in alpha quartz (α-SiO2) is presented. Single crystals of α-SiO2 were irradiated with two highly energetic ions to different nominal fluences. As expected, the morphology of the resulting ion tracks depends on the energy of the incident ion and their stopping powers within the target material. Subsequent chemical …

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Tunable-Focus Liquid Lens Through Charge Injection, Shizhi Qian, Wenxiang Shi, Huai Zheng, Zhaohui Liu Jan 2020

Tunable-Focus Liquid Lens Through Charge Injection, Shizhi Qian, Wenxiang Shi, Huai Zheng, Zhaohui Liu

Mechanical & Aerospace Engineering Faculty Publications

Liquid lenses are the simplest and cheapest optical lenses, and various studies have been conducted to develop tunable-focus liquid lenses. In this study, a simple and easily implemented method for achieving tunable-focus liquid lenses was proposed and experimentally validated. In this method, charges induced by a corona discharge in the air were injected into dielectric liquid, resulting in “electropressure” at the interface between the air and the liquid. Through a 3D-printed U-tube structure, a tunable-focus liquid lens was fabricated and tested. Depending on the voltage, the focus of the liquid lens can be adjusted in large ranges (−∞ to −9 …

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Fluorescence Microscopy With Tailored Illumination Light, Jialei Tang Jan 2020

Fluorescence Microscopy With Tailored Illumination Light, Jialei Tang

Electronic Theses and Dissertations, 2020-2023

Fluorescence microscopy has long been a valuable tool for biological and medical imaging. Control of optical parameters such as the amplitude, phase, polarization and propagation angle of light gives fluorescence imaging great capabilities ranging from single molecule imaging to long-term observation of living organisms. While numerous fluorescence imaging techniques have been developed over the past decades, there is always an inevitable tradeoff among the spatial resolution, imaging speed, contrast, photodamage and the total cost when it comes to choose the appropriate microscope. A main goal of my dissertation research is to develop state-of-the-art microscope systems that exhibit unprecedented performance in …

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High Performance Micro-Scale Light Emitting Diode Display, Fangwang Gou Jan 2020

High Performance Micro-Scale Light Emitting Diode Display, Fangwang Gou

Electronic Theses and Dissertations, 2020-2023

Micro-scale light emitting diode (micro-LED) is a potentially disruptive display technology because of its outstanding features such as high dynamic range, good sunlight readability, long lifetime, low power consumption, and wide color gamut. To achieve full-color displays, three approaches are commonly used: 1) to assemble individual RGB micro-LED pixels from semiconductor wafers to the same driving backplane through pick-and-place approach, which is referred to as mass transfer process; 2) to utilize monochromatic blue micro-LED with a color conversion film to obtain a white source first, and then employ color filters to form RGB pixels, and 3) to use blue or …

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Ev Charging Behavior Analysis Using Hybrid Intelligence For 5g Smart Grid, Yi Shen, Wei Fang, Feng Ye, Michel Kadoch Jan 2020

Ev Charging Behavior Analysis Using Hybrid Intelligence For 5g Smart Grid, Yi Shen, Wei Fang, Feng Ye, Michel Kadoch

Electrical and Computer Engineering Faculty Publications

With the development of the Internet of Things (IoT) and the widespread use of electric vehicles (EV), vehicle-to-grid (V2G) has sparked considerable discussion as an energy-management technology. Due to the inherently high maneuverability of EVs, V2G systems must provide on-demand service for EVs. Therefore, in this work, we propose a hybrid computing architecture based on fog and cloud with applications in 5G-based V2G networks. This architecture allows the bi-directional flow of power and information between schedulable EVs and smart grids (SGs) to improve the quality of service and cost-effectiveness of energy service providers. However, it is very important to select …

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Gravity-Drawing Flexible Silicone Filaments As Fiber Optics And Model Foldamers, Katherine Snell Jan 2020

Gravity-Drawing Flexible Silicone Filaments As Fiber Optics And Model Foldamers, Katherine Snell

CMC Senior Theses

Here, we present a method of gravity-drawing polydimethylsiloxane (PDMS) silicone fibers with application as fiber optics and as model foldamers. Beginning as a viscous liquid, PDMS is cured using heat until its measured viscosity reaches 4000 mPa•s. The semi-cured elastomer is then extruded through a tube furnace to produce thin (diameters on the order of hundred micrometers) filaments with scalable lengths. PDMS is biocompatible, gas-permeable, flexible, and hydrophobic. Additionally, the PDMS surface hydrophobicity can be modified via UV exposure, O2 plasma, and corona discharge. We demonstrate the patternibility (i.e patterns of hydrophobicity) of PDMS fibers, adding complexity to potential foldamer …

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Electrodynamics Modeling Of Plasmonic-Organic Hybrid Waveguides, Marcus Michel Jan 2020

Electrodynamics Modeling Of Plasmonic-Organic Hybrid Waveguides, Marcus Michel

Pomona Senior Theses

Optical fibers have multiple advantages over conventional electrical connections, such as lower energy losses and higher bandwidth. To use optics for chip-to-chip communication, electro-optic (EO) modulators need to be scaled down to be incorporated on integrated circuits. This size reduction has been accomplished using plasmonic-organic hybrid (POH) waveguides, which make use of nonlinear organic EO materials and surface plasmon polaritons to achieve light modulation in devices with lengths on the micron scale. As these devices are just starting to be developed, there are many avenues for their potential optimization. In order to streamline and reduce the cost of the optimization …

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Acoustics To Quantum Materials: A Centennial History Of The Department Of Physics, University Of Arkansas, Rajendra Gupta, Paul C. Sharrah Jan 2020

Acoustics To Quantum Materials: A Centennial History Of The Department Of Physics, University Of Arkansas, Rajendra Gupta, Paul C. Sharrah

Physics Faculty Publications and Presentations

The department of physics at the University of Arkansas was established in the 1907-08 academic year, although physics was taught from the very start of the University in 1872. The department celebrated its centennial in 2007-2008. Acoustics to Quantum Materials is a centennial history of the department covering the period 1907-08 to 2007-08. While the emphasis is on this period, instruction of physics over the period 1872-1907 is covered in two prologues, and the period 2009-18 is briefly covered in an epilogue. The first research laboratory to be established was in the area of acoustics. Subsequently, the department’s faculty have …

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Glaciernet: A Deep-Learning Approach For Debris-Covered Glacier Mapping, Zhiyuan Xie, Umesh K. Haritashya, Vijayan K. Asari, Brennan W. Young, Michael P. Bishop, Jeffrey S. Kargel Jan 2020

Glaciernet: A Deep-Learning Approach For Debris-Covered Glacier Mapping, Zhiyuan Xie, Umesh K. Haritashya, Vijayan K. Asari, Brennan W. Young, Michael P. Bishop, Jeffrey S. Kargel

Electrical and Computer Engineering Faculty Publications

Rising global temperatures over the past decades is directly affecting glacier dynamics. To understand glacier fluctuations and document regional glacier-state trends, glacier-boundary detection is necessary. Debris-covered glacier (DCG) mapping, however, is notoriously difficult using conventional geospatial technology methods. Therefore, in this research for automated DCG mapping, we evaluate the utility of a convolutional neural network (CNN), which is a deep learning feed-forward neural network. The CNN inputs include Landsat satellite images, an Advanced Land Observation Satellite (ALOS) digital elevation model (DEM) and DEM-derived land-surface parameters. Our CNN based deep-learning approach named GlacierNet was designed by appropriately choosing the type, number …

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Mitosisnet: End-To-End Mitotic Cell Detection By Multi-Task Learning, Md Zahangir Alom, Theus Aspiras, Tarek M. Taha, Tj Bowen, Vijayan K. Asari Jan 2020

Mitosisnet: End-To-End Mitotic Cell Detection By Multi-Task Learning, Md Zahangir Alom, Theus Aspiras, Tarek M. Taha, Tj Bowen, Vijayan K. Asari

Electrical and Computer Engineering Faculty Publications

Mitotic cell detection is one of the challenging problems in the field of computational pathology. Currently, mitotic cell detection and counting are one of the strongest prognostic markers for breast cancer diagnosis. The clinical visual inspection on histology slides is tedious, error prone, and time consuming for the pathologist. Thus, automatic mitotic cell detection approaches are highly demanded in clinical practice. In this paper, we propose an end-to-end multi-task learning system for mitosis detection from pathological images which is named"MitosisNet". MitosisNet consist of segmentation, detection, and classification models where the segmentation, and detection models are used for mitosis reference region …

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Birefringent Optofluidic Gratings, Sergio Calixto, Jose L. Garcia-Cordero, Diana F. Cedillo-Alcantar, Izabela Naydenova, Guillermo Garnica Jan 2020

Birefringent Optofluidic Gratings, Sergio Calixto, Jose L. Garcia-Cordero, Diana F. Cedillo-Alcantar, Izabela Naydenova, Guillermo Garnica

Articles

A set of parallel microfluidic channels behaving as a diffraction grating operating in the Raman-Nath regime has been fabricated and studied. The diffraction efficiency of such structure can be tuned by selecting a liquid with a particular refractive index and/or optical anisotropy. Alternatively the optical properties of the liquid can be characterised by measuring the diffraction efficiency and the state of polarization of the diffracted beam. In this work, the microfluidic channels under study have been filled with penicillin molecules dissolved in water. Due to the chirality of the penicillin, the liquid has been found to have circular birefringence of …

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Sequence-Coded Coherent Laser Ranging With High Detection Sensitivity, Keren Shemer, Gil Bashan, H Hagai Diamandi, Yosef London, Tzur Raanan, Yochai Israelashvili, Alon Charny, Itzik Cohen, Arik Bergman, Nadav Levanon, Avi Zadok Jan 2020

Sequence-Coded Coherent Laser Ranging With High Detection Sensitivity, Keren Shemer, Gil Bashan, H Hagai Diamandi, Yosef London, Tzur Raanan, Yochai Israelashvili, Alon Charny, Itzik Cohen, Arik Bergman, Nadav Levanon, Avi Zadok

Advanced Science Research Center

The compression of extended, coded sequences allows for laser ranging measurements with low peak power levels. Previous realizations of this approach were restricted by additive noise of direct, incoherent detection. In this work we bring together pulse sequence coding and optical coherent detection to achieve very high sensitivity. Collected sequences with an overall energy equivalent to only 800 photons are successfully compressed. The observed sensitivity agrees with analytic predictions. Compared with incoherent detection, measurement durations are reduced by four orders of magnitude. The protocol is suitable for laser ranging over tens of kilometers, depending on atmospheric conditions.

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Iterative Optical Diffraction Tomography For Reconstruction Of Multiply-Scattering Objects, Shengli Fan Jan 2020

Iterative Optical Diffraction Tomography For Reconstruction Of Multiply-Scattering Objects, Shengli Fan

Electronic Theses and Dissertations, 2020-2023

As a label-free, non-destructive, high-resolution, and quantitative imaging technique, optical diffraction tomography (ODT) has been widely used to image biological samples and microstructures, such as cells, tissues, and optical fibers. The refractive-index (RI) distribution of an object is reconstructed from multi-view measurements of diffracted fields emerging from the object. Typical ODT setups include the object rotating configuration (ORC) and the illumination scanning configuration (ISC). One major limitation of ODT is that it is only applicable to weakly-scattering objects. In this dissertation, novel methods have been developed to overcome the reconstruction difficulty caused by multiple scattering, so as to extend ODT …

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Parallelized X-Ray Tracing With Gpu Ray-Tracing Engine, Joseph Ulseth Jan 2020

Parallelized X-Ray Tracing With Gpu Ray-Tracing Engine, Joseph Ulseth

Electronic Theses and Dissertations, 2020-2023

X-ray diffraction tomography (XDT) is used to probe material composition of objects, providing improved contrast between materials compared to conventional transmission based computed tomography (CT). In this work, a small angle approximation to Bragg's Equation of diffraction is coupled with parallelized computing using Graphics Processing Units (GPUs) to accelerate XDT simulations. The approximation gives rise to a simple yet useful proportionality between momentum transfer, radial distance of diffracted signal with respect to incoming beam's location, and depth of material, so that ray tracing may be parallelized. NVIDIA's OptiX ray-tracing engine, a parallelized pipeline for GPUs, is employed to perform XDT …

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