There is an unprecedented need in neuroscience and medical research for the precise imaging of individual neurons and their interconnectivity in an effort to achieve a more complete understanding of neurological illness and cognitive growth. While several imaging architectures successfully detect active neural tissue, fluorescent imaging through head-mounted microscopes is becoming a standard method of imaging neural circuitry in freely behaving animals. At Boston University, the Gardner Group developed a miniaturized, open-source, single-photon ‘finch-scope’ to spur rapid prototyping in head-mounted miniscope technology. While experimentally convenient, the finch-scope and other miniscope platforms are limited by their native depth of field and may only detect a thin layer of active neurons in a neurological volume. In this Master’s Thesis Project, I will investigate utilizing optical phase masks integrated in the Fourier plane of the finch-scope to invoke a less-diffractive Bessel point spread function. Next, I will experimentally justify the extended depth of field nature of these phase masks by imaging the axial profile of a 10μm fluorescent pinhole object with a modified finch-scope.

The goal of this study was to improve dosimetry for pelvic, lung, head and neck, and other cancers sites with aspherical planning target volumes (PTV) using a new algorithm for collimator optimization for intensity modulated radiation therapy (IMRT) that minimizes the x-jaw gap (CAX) and the area of the jaws (CAA) for each treatment field. A retroactive study on the effects of collimator optimization of 20 patients was performed by comparing metric results for new collimator optimization techniques in Eclipse version 11.0. Keeping all other parameters equal, multiple plans are created using four collimator techniques: CA0, all fields have collimators set to 0°, CAE, using the Eclipse collimator optimization, CAA, minimizing the area of the jaws around the PTV, and CAX, minimizing the x-jaw gap. The minimum area and the minimum x-jaw angles are found by evaluating each field beam’s eye view of the PTV with ImageJ and finding the desired parameters with a custom script. The evaluation of the plans included the monitor units (MU), the maximum dose of the plan, the maximum dose to organs at risk (OAR), the conformity index (CI) and the number of fields that are calculated to split. Compared to the CA0 plans, the monitor units decreased on average by 6% for the CAX method with a p-value of 0.01 from an ANOVA test. The average maximum dose remained within 1.1% difference between all four methods with the lowest given by CAX. The maximum dose to the most at risk organ was best spared by the CAA method, which decreased by 0.62% compared to the CA0. Minimizing the x-jaws significantly reduced the number of split fields from 61 to 37. In every metric tested the CAX optimization produced comparable or superior results compared to the other three techniques. For aspherical PTVs, CAX on average reduced the number of split fields, lowered the maximum dose, minimized the dose to the surrounding OAR, and decreased the monitor units. This is achieved while maintaining the same control of the PTV. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Thesis submitted in fulfilment of the requirements for the degree Doctor of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2014 / Three-dimensional (3D) artefact detection can provide the conception of vision and real time interaction of electronic products with devices. The orientation and interaction of electrical systems with objects can be obtained. The introduction of electronic vision detection can be used in multiple applications, from industry, in robotics and also to give orientation to humans to their immediate surroundings. An article covering holograms states that these images can provide information about an object that can be examined from different angles. The limitations of a hologram are that there must be absolute immobilization of the object and the image system. Humans are capable of stereoscopic vision where two images are fused together to provide a 3D view of an object. In this research, two digital images are used to determine the artefact position in space. The application of a camera is utilized and the 3D coordinates of the artefact are determined. To obtain the 3D position, the principles of the pinhole camera, a single lens as well as two image visualizations are applied. This study explains the method used to determine the artefact position in space. To obtain the 3D position of an artefact with a single image was derived. The mathematical formulae are derived to determine the 3D position of an artefact in space and these formulae are applied in the pinhole camera setup to determine the 3D position. The application is also applied in the X-ray spectrum, where the length of structures can be obtained using the mathematical principles derived. The XYZ coordinates are determined, a computer simulation as well as the experimental results are explained. With this 3D detection method, devices can be connected to a computer to have real time image updates and interaction of objects in an XYZ coordinate system. Keywords: 3D point, xyz-coordinates, lens, hologram

<p>  </p> <p>Integrated photonics has provided an elegant way to bring the table-top bulky optical systems from the research lab to our daily life, thanks to its compact size, robustness, and low power consumption. Over the past decade, Silicon Nitride (Si3N4) photonics has become a leading material platform, benefiting from its record-low loss, large Kerr nonlinearity, and compatibility with the foundry process. However, the lack of electro-optical effect makes it challenging to actively tune the Si3N4 photonic circuits for advanced applications, such as LiDAR, spectroscopy, and atomic clocks. During my PhD research, I have developed a new platform of piezoelectric control of Si3N4 photonics through stress-optical effect. By integrating an<br> Aluminum Nitride (AlN) piezoelectric actuator, I demonstrated the tuning of Si3N4 optical microring resonator at sub-microsecond speed with nano-Watt power consumption. Microwave frequency (GHz) acousto-optic modulation (AOM) is realized by exciting high-overtone bulk acoustic wave resonant modes (HBAR), which are tightly confined in an acoustic Fabry-Pérot cavity. Maximum of 9.2 GHz modulation is achieved which falls into the microwave X-band. </p> <p><br></p> <p>The applications of the Piezo-on-Photonic platform are extensively explored in the quasi-DC and high frequency regimes. By working as a stress-optical tuner at low frequency, it allows me to actively tune a Kerr frequency comb into different states, and stabilize it over several hours, which can serve as the light source for the next-generation chip-based LiDAR engine. On the other hand, the GHz frequency AOM has helped me demonstrate a magnetic-free integrated optical isolator, a device that transmits light in only one direction. Three AlN HBAR actuators are integrated closely on the same Si3N4 microring resonator, which generate an effective rotating acoustic wave and break the transmission reciprocity of the light. A maximum of 10 dB isolation is achieved under 300 mW total radiofrequency power, with minimum insertion loss of 0.1 dB. Finally, the application of the same technique in quantum microwave to optical converter is theoretically analyzed, showing potential for building future quantum networks. The initial experimental attempt and outlook for future improvements are investigated. </p> <p><br></p> <p>In conclusion, this thesis investigated a novel Piezo-on-Photonic platform for flexible and efficient control of the Si3N4 photonic system, and its applications in a wide variety of advanced devices are demonstrated, with the potential of being key building blocks for future optical systems on-chip.  </p>

No description available.

<div>The purpose of this thesis was to investigate the possibility of Optical Frequency Identification (OFID) technology being used as a communication pathway for devices in LiFi systems that serve to open alternative transmission paths for Internet-of-Things infrastructure. LiFi or light-fidelity, plays off the concept of wireless-fidelity, commonly known as WiFi, and follows the trend of moving to higher frequencies within the electromagnetic spectrum. LiFi lies within the visual light and infrared wavelength range, which can be referred to as the nanometer wave range. The developed optical communication testbed is a proof of concept showing that OFID technology, enabled by Gallium Arsenide solar cell emission, can communicate with Visual Light Communication (VLC) systems. The scope of the work entails the development of a testbed for a custom optical communications testbed for OFID linked to VLC communication by sending transmissions via powerline modulation. An optical receiver circuit was developed and tested, and integration and testing for powerline communication and LED luminaire were successful. Manchester encoded data was sent at 4800 bit rate optically from an infrared light source, received by the developed receivers and was decoded. Information was successfully transmitted over powerline from computer terminal to LED luminaire output at 2400, 3600, 4800, 7200, and 9600 bit rate. Integration of these communication links did not occur due to Purdue University closure of campus related activities from COVID-19.<br></div>

No description available.

Thesis (M. Tech. (Engineering: Mechanical)) -- Central University of Technology, Free State, / The Centre for Rapid Prototyping and Manufacturing (CRPM) at the Central University of Technology, Free State (CUT) manufactures implants using Electro Optical Systems (EOS) titanium Ti-6Al-4V alloy powder (further referred to as EOS Ti64 powder) by means of Direct Metal Laser Sintering (DMLS) process on the EOSINT M 270 machine. For this reason, there is a need to characterise and acquire knowledge of the basic properties of direct metal laser sintered EOS titanium Ti-6Al-4V alloy samples (further referred to as DMLS Ti64 samples) under static tensile loading in order to provide the CRPM with engineering design data. The first objective of this Master’s study is to acquire the characteristics of EOS Ti64 powder in order to ascertain its suitability in the DMLS process. Secondly, the study aims to assess tensile properties and elastic constants of DMLS Ti64 samples produced from the set process parameters of EOSINT M 270 machine. Thirdly, it is to investigate microstructures of DMLS Ti64 samples subjected to different heat treatment techniques which will eventually assist in the determination of a suitable heat treatment technique that will yield higher ductility. Finally, the study aims to validate the static behaviour of DMLS Ti64 samples subjected to the static tensile loading up to a yield point in order to determine failure due to yielding. The samples were manufactured at CRPM Bloemfontein. The metallographic examinations, heat treatment and the determination of mechanical properties were done at the CSIR in Pretoria. Optical Microscope (OM) and Scanning Electron Microscope (SEM) were used to determine microstructures of DMLS Ti64 samples while Energy Dispersive X-Ray (EDX) analyses were performed using SEM. The samples were heat treated at temperatures of 700, 1000 and 1100°C respectively, and subsequently either cooled with the furnace, air or were water quenched. The mechanical property tests included tensile, hardness and determination of elastic constants. The static behaviour of DMLS Ti64 samples under static tensile load up to a yield point was predicted and verified using ABAQUSTM Finite Element Analysis (FEA). The stress-strain curves from ABAQUSTM were interpreted using MDSolid program. The point of interest was Von Mises yield stress at 0.2% offset, in order to determine failure due to yielding. EOS Ti64 powder particles were spherical in shape and the alpha and alpha+beta phases were identified. As-laser sintered samples possess a very fine and uniform alpha case with islands of martensitic plates; samples were brittle and showed low levels of ductility with an average elongation of 2.6% and an area reduction of 3.51%. Ultrasonic test results showed that DMLS Ti64 samples have Young’s modulus of 115 GPa, Shear modulus of 43 GP, a bulk modulus of 109 GPa and Poisson’s ratio of 0,323 while the density was 4.4 g/cm3. Slow cooling of DMLS Ti64 samples from 1000 and 1100oC resulted in a microstructure constituted more by the alpha phase of lower hardness than those from 700oC and as-laser sintered samples. High hardness was obtained by water quenching. The water quenched samples showed martensitic transformation and high hardness when compared to furnace cooled samples. Beta annealing tailored a microstructure of as-laser sintered samples into a lamellar structure with different lath sizes as per cooling rate. Beta annealing improved ductility levels up to 12.67% elongation for samples furnace cooled for 4 hours and even higher to 18.11% for samples furnace cooled for 34 hours, while area reduction increased to 25.94% and 33.39%, respectively. Beta annealing conversely reduced yield strength by 19.89% and ultimate tensile strength was reduced by 23.66%. The calculated maximum Von Mises stresses found were similar to the FEA interpreted results. The average percentage error, without the stress concentration factor, was approximately 8.29%; with the stress concentration factor included, it was 0.07%. The small reaction forces induced in both x-axis and z-axis contributed to this error of 0.07% between the calculations and ABAQUSTM FEA results. Samples that were not heat treated fell outside the Von Mises criterion and failed due to yielding. This justified the brittleness found in the tensile test results where elongation and area reduction were 2.6% and 3.51% respectively. However, all samples that were heat treated fell within the Von Mises criterion. The objectives of this study were achieved; the mechanical properties were similar to those of standard specification for wrought annealed Ti-6Al-4V alloy for surgical implant applications and EOS GmbH manufacturer’s material data sheet. DMLS Ti64 samples must be beta annealed in order to attain higher levels of ductility. A recommendation was made to further investigate the effect of heat treatment on the other mechanical properties. Furthermore, detailed results of basic properties of DMLS Ti64 samples are provided in the appendices in chart format and were written on a CD disc.

<p><a>The quick, reliable, and sensitive detection of bacterial contamination is desired in areas such as counter bioterrorism, medicine, and food/water safety as pathogens such as<i> E. coli</i> can cause harmful effects with the presence of just a few cells. However, standard high sensitivity techniques require laboratories and trained technicians, requiring significant time and expense. More desirable would be a sensitive point-of-care device that could detect an array of pathogens without sample pre-treatment, or a continuous monitoring device operating without the need for frequent operator intervention.<br> <br> Optical microring resonators in silicon photonic platforms are particularly promising as scalable, multiplexed refractive index sensors for an integrated biosensing array. However, no systematic effort has been made to optimize the sensitivity of microrings for the detection of relatively large discrete analytes such as bacteria, which differs from the commonly considered cases of fluid or molecular sensitivity. This work demonstrates the feasibility of using high finesse microrings to detect whole bacterial cells with single cell resolution over a full range of potential analyte-to-sensor binding scenarios. Sensitivity parameters describing the case of discrete analyte detection are derived and used to guide computational optimization of microrings and their constituent waveguides, after considering a range of parameters such as waveguide dimension, material, modal polarization, and ring radius. The sensitivity of the optimized 2.5 µm radius silicon TM O-band ring is experimentally demonstrated with photoresist cellular simulants. A multiplexed optimized ring array is then shown to detect <i>E. Coli</i> cells in an experimental proof of concept.</a></p>

Chemical Oxygen Iodine Laser(COIL) is an electronic transition high energy chemical laser having a wavelength of 1.315 /mi. This is the first chemical laser to operate on an electronic rather than a rotational or vibrational transition. In principle the COIL can be operated either in pulsed or cw mode. Its interest lies in high chemical efficiency, high power and wavelength which is shortest among all the chemical lasers. COIL finds a wide range of applications as its output wavelength at 1.315/zm couples well with the surface of most metals. The applications include surface hardening and modification of metals, welding, drilling and cutting of metals, cutting of ceramics, micro machining, laser deposition of non metallic coatings on metallic surfaces, monitoring of atmospheric pollutants and solar hazardous waste detoxification. Moreover, its wavelength is suitable for fiber optic transmission. In COIL the laser output at 1.315 /an is achieved by stimulated emission on the f (2-PL/2) -* -f (2-p3/2) magnetic dipole transition in atomic iodine. The population inversion on this transition is obtained by resonant collisions! energy transfer from metastable excited Oj^A) molecules produced by a chemical reaction of KOH, H2O? and Cl2. The chemical reaction of H2O2 and Cl2 that produces oxygen molecules is highly exothermic, and because of spin conservation considerations, channels its energy directly into the metastable electronically excited singlet delta state of oxygen molecule. Since the O2(1A) has a 45 mins lifetime and hence an extremely low small signal gain coefficient, it cannot be lased directly. Lasing can be achieved, however, if this energy is transferred to an atom or molecule which has a reasonable transition moment between its excited and ground states. The iodine 52P^2 -> 52P3/2 magnetic dipole transition has an acceptable transition moment and is nearly resonant with the 02{lA) state in oxygen. Excited iodine atoms are obtained by mixing O2(l A) and l2 molecules resulting in their dissociation and subsequent excitation. Power levels in excess of 25 kW have been reported in COIL. Due to wide range of applications and mainly for its use as a laser weapon, efforts are being made to enhance the power to higher levels. The dissociation of I2 controls the gain of the coil and hence power. In the pure COIL scheme some of the I2 remains undissociated due to the recombination reactions. Hence if we add a mechanism to dissociate the residual I2 molecules, we can enhance the performance of the COIL. So we propose to add a solar pumping to conventional COIL, which by photo exciting the undissociated I2lead to increase in efficiency. The thesis contains six chapters in which chapter 1 contains a general introduction and the definition of the research problem. The basic theory and the chemical reactions are discussed in chapter 2, The proposed model is discussed and the rate equations are solved in chapter 3. The numerical scheme and the computer code along-with the validation of the code are presented in chapter 4. The numerical results for the species concentrations, population inversion density and the output power for the proposed solar pumped COIL are presented in chapter 5, Final conclusions and future scope of the proposed research are presented in the final chapter 6. (Pl refer the original document for formulas)