Engineering Commons^™

Signal Processing Algorithms For Doppler Lidar Sensors, Samantha Grubb

Physics and Astronomy Honors Papers

Light detection and ranging (LiDAR) is a remote sensing technology that obtains relative distance and velocity measurements between a sensor and a defined target by using light transmitted and received from the target. FMCW Doppler LiDAR, a particular variant of LiDAR, functions by analyzing the frequency shift in the reflected light to determine the target's range and velocity. This technology plays a crucial role across various sectors including defense, aerospace, and automotive. This paper presents signal processing algorithms designed to optimize data obtained from Doppler LiDAR sensors. By applying various window functions to time domain data, the Signal-to-Noise Ratio (SNR) …

Multi-Scale Modeling Of Selective Laser Sintering: From Manufacturing Process And Microstructure To Mechanical Performance In Semi-Crystalline Thermoplastics, Cameron Zadeh

All Dissertations

Selective laser sintering is an additive manufacturing process that opens many design possibilities but is limited in its reliability and reproducibility. Numerical simulations validated by experimental data yield insights into the process and resulting part properties, allowing users to make more informed decisions. In this dissertation, a model for the process and microstructure is developed and validated, followed by a coupling to mechanical models to predict part performance. Further developments include a new addition of a reaction kinetics model to the process model to describe the interplay between thermal degradation and melt pool properties, and an exploration of the parameter …

Quantitative, Photocurrent Multidimensional Coherent Spectroscopy, Adam Halaoui

Electronic Theses and Dissertations

Multidimensional coherent spectroscopy (MDCS) is a quickly growing field that has a lot of advantages over more conventional forms of spectroscopy. These advantages all come from the fact that MDCS allows us to get time resolved correlated emission and absorption spectra using very precisely chosen interactions between the density matrix and the excitation laser. MDCS spectra gives the researcher a lot of information that can be extracted purely through qualitative analysis. This is possible because state couplings are entirely separated on the spectra, and once we know how to read the data, we can see how carriers transport in the …

Tunable Linear And Nonlinear Metasurfaces Based On Hybrid Gold-Graphene Plasmons, Matthew Feinstein

Dissertations, Theses, and Capstone Projects

Optical Metasurfaces are planar structures that are patterned with subwavelength structures and are very thin compared to the wavelength of light. Despite their thinness, these structured materials can strongly interact with incident light to effect the functionalities of conventional optical components, such as rotation of the polarization state, beam steering, lensing, spectral filtering, and holography, to name a few. Metasurfaces can also facilitate nonlinear optical effects, such as the mixing of beams at different frequencies to generate a beam at a new frequency.

The ability to alter the behavior of a metasurface during operation is highly desired for applications such …

Photophoretic Optical Trapping, Essa Ababseh

Electrical Engineering

Photophoretic Optical Trapping (POT) is a relatively new concept in the field of optics which has potential application in 3D display. The POT is realized by confining a particle within a very small location of the optical system, mostly around the focus. The particle, if captured by the beam, has the potential to print visible 3D images in free space. Our POT system is encapsulated by an acrylic enclosure, which also incorporates a biconvex lens as well as an adjustable focus laser module. Particles are released around the top of the lens’ focal point until the captured particle can be …

Monitoring Blood Flow In Animal Models Using A Camera-Based Technique, Dharminder Singh Langri

Browse all Theses and Dissertations

Blood flow dynamics plays a critical role in maintaining tissue health, as it delivers nutrients and oxygen while removing waste products. It is especially important when there is a disruption in cerebral autoregulation due to trauma, which can induce ischemia or hyperemia and can lead to secondary brain injury. Thus, there is a need for noninvasive techniques that can allow continuous monitoring of blood flow during intervention. Optical techniques have become increasingly practical for measuring blood flow due to their non-invasive, continuous, and relatively lower-cost nature. This research focused on developing a low-cost, scalable optical technique for measuring blood flow …

Optical Control System For Atmospheric Turbulence Mitigation, Martyn Lemon

All Theses

Propagation of laser light is distorted in the presence of atmospheric turbulence. This poses an issue for sensing, free-space optical communications, and transmission of power. With an ever-increasing demand for high-speed data communications, particularly between satellites, unmanned vehicles, and other systems that benefit from a point-to-point link, this issue is critical for the field. A variety of methods have been proposed to circumvent this issue. Some major categories include the manipulation of the light’s structure, an adaptive scheme at the optical receiver, scanning mirror systems, or a transmission of simultaneous signals with a goal to improve robustness.

There is an …

Investigation Of Laser And Nonlinear Properties Of Anderson Localizing Optical Fibers, Cody Ryan Bassett

Optical Science and Engineering ETDs

In this dissertation, I investigate the possibility of lasing and nonlinear phenomena in completely solid-state transverse Anderson localizing optical fibers (TALOFs). I examine three areas within this range of topics. The research in nonlinear phenomena focuses on four-wave mixing (FWM). FWM is of high interest in TALOFs due to the fact that guided localized modes of the fiber each have different propagation constants, and thus unique possible FWM pairs can be generated from the same input pump beam. I demonstrate the generation of FWM in the TALOF by pumping it with 532 nm light into a localized mode and observing …

Maximum Trapping Focal Length In Photophoretic Trap For 3d Imaging Systems, Jason M. Childers

Electrical Engineering

This product is a photophoretic trapping system which allows varying focal lengths to test which focal lengths are possible for trapping toner particles. This system establishes that there exists a maximum trapping distance limitation and is the first time the effect of focal length is studied in a photophoretic trapping system. Increasing photophoretic trapping focal length is necessary for improving this technology as a 3D display. The 3D imaging technology is realized by dragging a microscopic (micrometer-scale) particles with a laser beam to trace an image. This technology can display fully colored and high-resolution 3D images visible from almost any …

Further Exploration Of Optical/Thermal Interaction Effects On High-Power Laser System Performance And Optimization Through Multiphysics System-Level Modeling, Nathaniel J. Butt

Browse all Theses and Dissertations

High-power laser systems (HPLS) have wide-ranging applications in many prominent areas. HPLS use laser diodes to pump fiber gain media. Understanding the functionality of both components is critical for achieving effective HPLS operation. System optical efficiency is a function of diode junction temperature. As junction temperature changes, the wavelength spectrum of the diode output shifts causing optical power losses in the fiber gain media. Optical/thermal interactions of the dynamically coupled laser diodes and fiber gain media are not fully understood. A system level modeling approach considering the interactions between optical performance and component temperature is necessary. Four distinct models were …

Detecting A Heterogenous Sample Of Pigmented Melanoma Cell Lines Using Photoacoustic Flow Cytometry, Margaret Cappellano

Electronic Theses and Dissertations

Metastatic melanoma is the deadliest form of skin cancer, which is in part, attributed to its rapid aggression and lack of response to typical treatment methods. There are far too often cases where a lymph node biopsy does not detect the severity of the cancer, which in turn causes a lack of diagnosis until a mass can be visually detected on a scan, such as a PET, CT, or MRI. Once visible on a scan, the cancer is too progressive for successful treatment. To avoid this, we investigated how a blood sample can be used to negate a missed diagnosis, …

Optical Study Of 2-D Detonation Wave Stability, Eulaine T. Grodner

Theses and Dissertations

Fundamental optical detonation study of detonations constricted to a 2-d plane propagation, and detonations propagating around a curve. All images were processed using modern image processing techniques. The optical techniques used were shadowgraph, Schlieren, and chemiluminescence. In the 2-Dstraight channels, it was determined wave stability was a factor of cell size. It was also determined the detonation wave thickness (area between the combustion and shockwave) was a factor of how much heat available for the detonation. For the detonations propagating around a curve, it was determined the three main classifications of wave stability were stable, unstable, and detonation wave restart. …

Aqueous Fabrication Of Pristine And Oxide Coated Znse Nanoparticles, Nicholas L. Van Zandt

Browse all Theses and Dissertations

Semiconducting nanoparticles have received significant attention due to their unique optoelectronic properties. Quantum dots (QDs), a class of spherical nanoparticles, possess a size-dependent bandgap and photoluminescence at visible wavelengths. QDs have many applications including biological labelling, solar cells, chemical impurity detection, and optical glasses. Doping QDs into optical glasses is highly desirable. High-quality QDs can be synthesized via liquid solution methods. However, solution-synthesized QDs often degrade over time and they cannot survive incorporation into a glass melt without protection. In this work, the aqueous synthesis of ZnSe QDs and coating with nanometer silica and alumina protective shells are investigated. The …

Noninvasive Blood Flow And Oxygenation Measurements In Diseased Tissue, Benjamin S. Rinehart

Browse all Theses and Dissertations

The research presented in this dissertation focused on the application of optical imaging techniques to establish blood flow and oxygen saturation as effective biomarkers for two disease cases, Autism Spectrum Disorder (ASD) and Huntington’s Disease (HD). The BTBR mouse model of ASD was utilized to validate measurements of cerebral blood flow and oxygenation as biomarkers for autism. The R6/2 mouse model of juvenile HD was utilized to validate measurements of skeletal muscle blood flow following tetanic muscle contractions induced by electrical nerve stimulation. Next, a noncontact, camera-based system to measure blood flow and oxygen saturation maps was implemented to improve …

Novel Methods In Computational Imaging With Applications In Remote Sensing, Adam Webb

Dissertations, Master's Theses and Master's Reports

This dissertation is devoted to novel computational imaging methods with applications in remote sensing. Computational imaging methods are applied to three distinct applications including imaging and detection of buried explosive hazards utilizing array radar, high resolution imaging of satellites in geosynchronous orbit utilizing optical hypertelescope arrays, and characterization of atmospheric turbulence through multi-frame blind deconvolution utilizing conventional optical digital sensors.

The first application considered utilizes a radar array employed as a forward looking ground penetrating radar system with applications in explosive hazard detection. A penalized least squares technique with sparsity-inducing regularization is applied to produce imagery, which is consistent with …

Saturation Behaviors In Deep Turbulence, Jeffrey R. R. Beck

Dissertations, Master's Theses and Master's Reports

Distributed-volume atmospheric turbulence near the ground significantly limits the performance of incoherent imaging and coherent beam projection systems operating over long horizontal paths. Defense, military and civilian surveillance, border security, and target identification systems are interested in terrestrial imaging and beam projection over very long horizontal paths, but atmospheric turbulence can blur the imagery and aberrate the laser beam such that they are beyond usefulness. While many post-processing and adaptive optics techniques have been developed to mitigate the effects of turbulence, many of these techniques do not work as expected in stronger volumetric turbulence, or in many cases don't work …

Linear And Nonlinear Optical Effects In High Carrier Concentration Oxides And Nitrides At Epsilon-Near-Zero, Ray Secondo

Theses and Dissertations

Nonlinear optics has been an important method for achieving ultrafast light manipulation. Recently, ENZ material have gained interest due to inherent advantages such as slow light, improved confinement, and ideal relaxation times, the nonlinear response of these materials, such as the intensity-dependent-refractive-index, are ultra-large yet remain ultra-fast. This experimental discovery of epsilon-near-zero enhancement has thus opened new avenues in nonlinear optics research in recent years, and while experiments have continued to progress a theoretical understanding of the processes and origins of nonlinear optical enhancement at epsilon-near-zero has lagged.

To fill this gap, the work herein focuses on uncovering the mechanisms …

The Aging And Impacts Of Atmospheric Soot: Closing The Gap Between Experiments And Models, Ogochukwu Yvonne Enekwizu

Dissertations

The main goal of this dissertation is to generate data and parameterizations to accurately represent soot aerosols in atmospheric models. Soot from incomplete combustion of fossil fuels and biomass burning is a major air pollutant and a significant contributor to climate warming. The environmental impacts of soot are strongly dependent on the particle morphology and mixing state, which evolve continuously during atmospheric transport via a process known as aging. To make predictions of soot impacts on the environment, most atmospheric models adopt simplifications of particle structure and mixing state, which lead to substantial uncertainties. Using an experimentally constrained modeling approach, …

Prototype Instrument Development For Measuring Directionality Of Aerosol Light Scattering, Esther K. Monroe

McKelvey School of Engineering Theses & Dissertations

Investigation of aerosol interactions with electromagnetic waves provides insights into the scattering particles. Aerosol phase function, an angular distribution of scattered light, is a value required to calculate parameters used in direct radiative forcing (DRF) models in the atmosphere. Currently no direct measurement of phase function is available hence it is estimated from ground observations such as backscatter fraction b and subsequently relating the parameters via Henyey-Greenstein (HG) approximation. This method has shown to introduce errors in radiation transfer models. HG phase function, in particular, does not account for particle microphysical properties such as shape and refractive index. Given the …

Miniaturized Ultraviolet Imager Phase Iii, Bradley D. Albright, Nicolas A. Armenta, Colin W. Harrop

Mechanical Engineering

This document details the work to date, June 9, 2020, done by the Cal Poly Mechanical Engineering senior project team, Miniaturized Ultraviolet Imager: Phase III (MUVI III), sponsored by the University of California, Berkeley – Space Sciences Laboratory (UCB SSL). MUVI III is the third senior project team of an ongoing design, MUVI: the prototype of a 2U sized CubeSat intended to capture aurora images in the ionosphere. The first team, MUVI I, finished development of the UV imager. The second team, MUVI II, designed the mirror mounting and deployable door mechanisms. The goal of MUVI phase III is to …

Construction Of A Hyperspectral Imager Using 3d-Printed And Off-The-Shelf Components, Joshua Moorhouse

Mechanical Engineering Undergraduate Honors Theses

The Arkansas Center for Space and Planetary Sciences is working in collaboration with the Mechanical Engineering department to create a relatively cheap and modifiable hyperspectral imager. It is constructed using 3D-printed and off-the-shelf components from Edmund Optics and Amazon. The iteration created in this paper delivers spectrograms in the visible spectrum. The long-term goals of the camera are to create hyperspectral images from these spectrograms and to advance the imager into the infrared and near-infrared spectra. This imager is being developed to be used in the Arkansas Center for Space and Planetary Sciences environmental test chambers to further the scientific …

Optics Of Two-Dimensional Materials Used As Substrates For Nanoparticle-Based Devices, Reagan Newman

Chancellor’s Honors Program Projects

No abstract provided.

The Design Of A Continuous Wave Molecular Nitrogen Stimulated Raman Laser In The Visible Spectrum, Timothy J. Bate

Theses and Dissertations

Hollow-core photonic crystal fibers (HCPCFs) shows promise as a hybrid laser with higher nonlinear process limits and small beam size over long gain lengths. This work focuses on the design of a CW molecular nitrogen (N₂) stimulated Raman laser. N₂ offers Raman gains scaling up to 900 amg, scaling higher than H₂. The cavity experiment showed the need to include Rayleigh scattering in the high pressure required for N₂ Raman lasing. Even at relatively low pressure ssuch as 1,500 psi, high conversion percentages should be found if the fiber length is chosen based on …

Estimation Of Atmospheric Conditions Over A Long Horizontal Path Using Multi-Frame Blind Deconvolution (Mfbd) Techniques In Comparison With Delayed Tilt Anisoplanatism (Delta) Software, Hannah Stoll

Dissertations, Master's Theses and Master's Reports

The potential to track and view objects in space from the ground with greater near real time knowledge of the intervening turbulence would be a revolutionary capability. The objective of this thesis is to cross-validate two separate methods used to estimate the Fried parameter. This verification is a step toward a commercial grade product that would make real-time estimates of the turbulence strength along an optical path from a ground-based observatory to a satellite in orbit around the Earth. Michigan Technological University has developed a multi-frame blind deconvolution (MFBD) algorithm used to estimate r0 and it was tested against MZA’s …

Quantitative Analysis Techniques For Assessing Organelle Organization And Dynamics In Individual Cells, Isaac Vargas

Graduate Theses and Dissertations

In biomedical optics and microscopy, the organization and morphology of organelles have been widely studied. In spite of novel imaging techniques, there is still a lack of quantitative tools to easily measure cellular characteristics from image data. Previous studies have explored multiple approaches to assess organelle organization and alignment, resulting in complicated and extensive algorithms that are both subject to multiple steps of image processing and influenced by non-cellular artifacts. In this thesis, a technique called the Modified Blanket Method (MBM) is introduced to quantify organelle organization through measurements of fractal dimension (FD) on a pixel-by-pixel basis. With the use …

A Rotating Aperture Mask For Small Telescopes, Edward L. Foley

Master's Theses

Observing the dynamic interaction between stars and their close stellar neighbors is key to establishing the stars’ orbits, masses, and other properties. Our ability to visually discriminate nearby stars is limited by the power of our telescopes, posing a challenge to astronomers at small observatories that contribute to binary star surveys. Masks placed at the telescope aperture promise to augment the resolving power of telescopes of all sizes, but many of these masks must be manually and repetitively reoriented about the optical axis to achieve their full benefits. This paper introduces a design concept for a mask rotation mechanism that …

Tailored Frequency Comb Structures And Their Sensing Applications, James Hendrie

Optical Science and Engineering ETDs

The focus of this dissertation is the development and investigation of nested cavity mode-locked lasers and their resultant tailored frequency combs. A nested cavity is made up of two cavities, known as parents. One parent is a larger, active, 100MHz Ti:Saph oscillator and the other is a smaller, passive, 7GHz Fabry-Perot Etalon (FPE). Unlike standard frequency combs that are continuous, a tailored comb’s teeth are distributed in equally spaced groups where the center of each group corresponds to the resonance of the FPE and the side bands are determined by the resonances of the Ti:Saph. This unique coupling of the …

Design, Construction And Application Of A Home-Built, Two-Photon Microscope, William P. Breeding

Electronic Theses and Dissertations

Two-photon microscopy (TPM) is a powerful, versatile imaging modality for the study of biological systems. This thesis overviews the relevant physics involved in TPM, design considerations and process of constructing a home-built, two-photon microscope, and provides a set of procedures to operate the system. Furthermore, this work explores several applications of TPM through the study of single-cell metabolism and imaging the cellular-material interface. Explored in particular depth was the imaging of cellulose nanofiber (CNF) materials, with the goal of understanding the three-dimensional nature of fibroblast cell growth when embedded within the materials. This work uncovered several optical properties of CNF, …

Generation And Use Of Femtosecond, Gigawatt, Near Infrared Laser Pulses From An Amplified, Mode-Locked, Ti:Sapphire Laser, David Anthony Valdés

Optical Science and Engineering ETDs

This work modeled the early to middle successes achieved in the field of ultrafast, high peak power optics, beginning with the work of Nobel Prize winners Donna Strickland and Gérard Mourou in 1985. In our work, 100 fs light pulses of around 800 nm were generated by a Ti:Sapphire oscillator, then amplified to approximately 30 GW peak power using a chirped pulse amplification system that included regenerative and multi-pass amplifiers. As a verification of our pulses having high peak powers and ultrashort durations, they were then used to strike water, glass, and a Kerr Cell. Supercontinuum generation was observed as …

Construction Of A Hyperspectral Camera Using Off-The-Shelf Parts And 3d-Printed Parts, Connor Heo

Mechanical Engineering Undergraduate Honors Theses

The Arkansas Center for Space and Planetary Sciences (ACSPS) is working together with the Mechanical Engineering Department to build a modifiable camera with 3D-printed parts and off-the-shelf parts (sourced from Edmund Optics and Amazon). The design is to be readily changeable, primarily with the 3D printed parts, as to accommodate new ideas and functionalities in the future. Ultimately, the camera should be relatively cheap while maintaining functionality for proposed use cases. Earlier versions of the design will be tested extensively and rapidly updated in the ACSPS labs with benchtop testing. This will involve subjects with both visible and infrared emissions, …