<p>Phase correction has the potential to increase the image quality of real-time 3D (RT3D) ultrasound, especially for transcranial ultrasound. Such improvement would increase the diagnostic utility of transcranial ultrasound, leading to improvements in stroke diagnosis, treatment, and monitoring. This work describes the implementation of the multi-lag least-squares cross-correlation and partial array speckle brightness methods for static and moving targets and the investigation of contrast-enhanced (CE) RT3D transcranial ultrasound.</p><p>The feasibility of using phase aberration correction with 2D arrays and RT3D ultrasound was investigated. Using the multi-lag cross-correlation method on electronic and physical aberrators, we showed the ability of 3D phase aberration correction to increase anechoic cyst identification, image brightness, contrast-to-noise ratio (CNR), and, in 3D color Doppler experiments, the ability to visualize flow. With a physical aberrator, CNR increased by 13%, while the number of detectable cysts increased from 4.3 to 7.7.</p><p>We performed an institutional review board (IRB) approved clinical trial to assess the ability of a novel ultrasound technique, namely RT3D CE transcranial ultrasound. Using micro-bubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and 9 via the sub-occipital window and report our detection rates for the major cerebral vessels. In 82% of subjects, we identified the ipsilateral circle of Willis from the temporal window, and in 65% we imaged the entire circle of Willis. From the sub-occipital window, we detected the entire vertebrobasilar circulation in 22% of subjects, and in 50% the basilar artery. </p><p>We then compared the performance of the multi-lag cross-correlation method with partial array reference on static and moving targets for an electronic aberrator. After showing that the multi-lag method performs better, we evaluated its performance with a physical aberrator. Using static targets, the correction resulted in an average contrast increase of 22.2%, compared to 13.2% using moving targets. The CNR increased by 20.5% and 12.8%, respectively. Doppler signal strength and number of Doppler voxels increased, by 5.6% and 14.4%, respectively, for the static method, and 9.3% and 4.9% for moving targets. </p><p>We performed two successful in vivo aberration corrections. We used this data and measure the isoplanatic patch size to be an average of 10.1°. The number of Doppler voxels increased by 38.6% and 19.2% for the two corrections. In both volunteers, correction enabled the visualization of a vessel not present in the uncorrected volume. These results are promising, and could potentially have a significant impact on public health.</p><p>Lastly, we show preliminary work testing the feasibility of a unique portable dedicated transcranial ultrasound system capable of simultaneous scanning from all three acoustic windows. Such a system would ideally be used in a preclinical setting, such as an ambulance.</p> / Dissertation

Focal plane corrected Cassegrain type optical systems have been widely used in various fields. The axial alignment of complex optical systems is not easy and a practical alignment method is needed for such systems. Tilts, decenters and axial motion of elements or group of elements in the system are the typical alignment parameters. Interferometric measurement is an effective way to see the errors caused by the misalignment of each element in an optical system. In this thesis, alignment of a Cassegrain type telescope will be examined by using interferometric measurements and modulation transfer function simulations.

No description available.

This dissertation investigates challenges associated with optics in the 10-500 wavelength size regime. For the visible spectrum, this size range (5-250um) is classified as micro-optics, but is set apart from other size ranges by a noticeable lack of suitable simulation and metrology tools. Optics of this size are gaining popularity in applications such as solid immersion lenses (SIL) and laser beam shaping, but require more research into simulation, testing, fabrication, and assembly in order to be easily integrated into commercial applications.A survey of previous work on SILs and micro-optics simulation/testing is given, including past work with gallium phosphide (GaP) microlenses. A new SIL aberration treatment is described using spherical-parent 3rd order aberrations. Agreement is shown with previous work, and the lack of hemisphere approximations gives a broader understanding of aberrations for varying SIL thicknesses. Results show that aberration reduces with lens radius, but thickness tolerances become tighter as dimensions shrink. A study of GaP intrinsic birefringence and the theoretical impact on the induced polarization signal is also given.A survey of beam propagation simulators is given and a sequential piece-wise diffraction (SPWD) simulator is developed for arbitrary optical systems that overcomes the difficulties of simulation in the 10-500 wavelength size regime. A discussion of a future extension to the work to determine reflected and transmitted field amplitudes with a non-sequential method is presented with specific discussion on the challenges of electric field surface transfer.The design and operation of a micro-interferometer is discussed and testing results from the first sub-100um diameter GaP SILs are shown. A novel method for determining the shape profile of aspheric surfaces using information from annular fringes is presented. Theoretical beam shaping applications for micro GaP lenses is also discussed with results using the SPWD method. Experimental results are also shown for a 1x1x0.3mm beam shaper package that images a laser diode beam to an approximate size of 60um at a working distance of 4mm.Finally, designs and experimental results are shown for the integration of GaP micro-optics into conventional systems as SILs or beam-shaping elements including methods and equipment for lapping and polishing GaP.

The aim of this thesis has been summarized as the design of a micro-satellite camera system and its focal plane simulations. The average micro-satellite orbit heights ranges in between 600-850 km and obviously a multipayload satellite brings volume and power restrictions for each payload. In this work, an orbit height of 600 km and a volume of 20&times / 20&times / 30 cm is assumed, since minimizing the payload dimensions increases the probability of the launch. The pixel size and the dimensions of an imaging detector such as charge-coupled device (CCD) have been defined by the useful image area with acceptable aberration limits on the focal plane. In order to predict the minimum pixel size to be used at the focal plane modulation transfer function (MTF), point spread function (PSF), image distortion and aberration simulations have been carried out and detector parameters for the designed camera have been presented.

This thesis describes an analytical approach to the optical design of four-mirror anastigmatic optical systems. In all cases investigated here the object is at infinity. In the introduction the field of reflecting, or "catoptric", optical system design is discussed and given some historical context. The concept of the "simplest possible reflecting anastigmat" is raised in connection with Plate Diagram analysis. It is shown that four-plate systems are in general the simplest possible anastigmats, and that four-plate systems comprised of four spherical mirrors are the last family of "simplest possible reflecting anastigmats" for which the complete solution set remains unknown. In chapter 2 third-order aberration coefficients in wavefront measure are derived in a form that is particularly suitable for Plate Diagram analysis. These coefficients are subsequently used to describe the Plate Diagram, and to detail the application of the Plate Diagram to the survey of all possible solutions for four-spherical-mirror anastigmats. The Plate Diagram technique is also generalized to investigate its use as an optical design tool. In the example given a generalized Plate Diagram approach is used to determine solutions for four-mirror anastigmats with a prescribed first-order layout and a minimum number of conicoids. In chapter 3 results are presented for the survey of four-spherical-mirror anastigmats in which all elements are required to be smaller than the primary mirror. Two novel families of four-spherical-mirror anastigmats are presented and these are shown to be the only examples of four-spherical-mirror systems that exist under the given constraints. Chapter 4 gives an example of the application of Plate Diagram analysis to the design of an anastigmatic system with a useful first-order layout and a minimum number of conicoid mirrors. It is shown that systems with useful first-order layouts and only one conicoid mirror can be obtained using this method. In chapter 5 results are presented of the survey of all remaining four-spherical-mirror anastigmatic systems: that is systems in which elements are allowed to exceed the diameter of the entrance pupil, which includes systems with concave and convex primary mirrors. A wide variety of solutions are presented and classified according to both the underlying geometry of the solutions and the first-order layouts. Of these systems only one has been reported in previously published literature. The results presented in this thesis complete the set of "four-plate" reflecting anastigmats, and it can now be said that all possible solutions for four-spherical-mirror anastigmatic systems have been determined.

Thesis (M.S.)--Ohio University, June, 2002.

Submitted by Caroline Falcao (caroline.rfalcao@ufpe.br) on 2017-04-06T19:44:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2012-Dissertação-KleisonMerlo.pdf: 1387071 bytes, checksum: 3ebe03b22eb3efc7773006a1a48f6b26 (MD5) / Made available in DSpace on 2017-04-06T19:44:29Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2012-Dissertação-KleisonMerlo.pdf: 1387071 bytes, checksum: 3ebe03b22eb3efc7773006a1a48f6b26 (MD5) Previous issue date: 2012 / O formocresol, principal droga utilizada em pulpotomias, tem um longo e bem sucedido histórico de uso clínico. Contudo, sua segurança tem sido questionada devido a possíveis efeitos genotóxicos, mutagênicos e carcinogênicos, relacionados à presença do formaldeído em sua composição. Resultados de estudos sobre a genotoxicidade do formocresol são bastante inconsistentes, logo, uma avaliação mais aprofundada sobre seu potencial genotóxico se faz relevante, uma vez que é uma droga mundialmente utilizada. Nesse trabalho foram investigados os potenciais efeitos genotóxicos do formocresol através de ensaios citogenéticos in vitro e in vivo (teste de metáfase). Nos ensaios in vitro, as preparações cromossômicas foram obtidas de cultura de linfócitos, onde após 24 horas de incubação, 50 µl das diluições do formocresol (1:50, 1:100, 1:200, 1:500, 1:1000) foram adicionados, sendo as preparações citológicas realizadas após 48 e 72 horas. Para o controle negativo foram realizadas culturas sem adição de qualquer droga. Nos ensaios in vivo, camundongos Swiss webster foram inoculados com as mesmas diluições na proporção de 0,1 ml/10 g, sendo utilizado como controle positivo a ciclofosfamida (25 mg/kg) e como negativo a glicerina/água (1:1). Para análise estatística foi aplicado o teste do qui-quadrado ao nível de 5%. Em culturas de 48 e 72 horas, comparando-se as dosagens de 1:50 e 1:100 com o controle negativo foi constatado haver diferença significativa, o que não observou-se para as outras diluições. Ao comparar-se a diluição de 1:50 em machos e a diluição de 1:200 em fêmeas com o controle negativo houve diferença significativa, o que não foi observado para as outras diluições. Sob as condições experimentais empregadas nesse estudo, o formocresol revelou-se genotóxico nas diluições mais concentradas, contrariando alguns trabalhos que apontam para sua não genotoxicidade. Entretanto, a dose final de formaldeído presente nessas diluições parece ser superior àquela geralmente empregada em pulpotomias. Isso demonstra que o uso displicente do formocresol parece ser o principal responsável pelos efeitos genotóxicos relatados na literatura. / Formocresol, the main substance used in pulpotomies, has a long and successful historical of clinical use. Although, its safety has been questioned because of possible genotoxic, mutagenic and carcinogenic effects, related to the presence of formaldehyde on its composition. Results from studies about formocresol genotoxicity are quite inconsistent, so a deep evaluation about its genotoxic potential is important, once this medicament is widely used. The potential genotoxic effects of formocresol were investigated employing in vitro and in vivo cytogenetic assays (chromosomal aberration test). On in vitro assays chromosomal preparations were provided from lymphocyte cultures, where after 24 hours of incubation, 50 µl from formocresol dilutions (1:50, 1:100, 1:200, 1:500, 1:1000) were added, with the cytological preparations done after 48 and 72 hours. The negative control cultures were done without adding any drug. On in vivo assays Swiss webster mice were inoculated with the same dilutions using the proportion of 0,1 ml/10 g body weight, and for positive control was used cyclophosphamide (25 mg/kg) and as negative control glycerine/water (1:1). The statistical analysis was performed using chi-square test at 5% level. On 48 and 72 hours culture comparing the 1:50 and 1:100 dosages with the negative control was observed significant difference, the same was not observed with the other dilutions. Comparing 1:50 dilution of male and 1:200 dilution of female with the negative control any significant difference was observed, the same did not happen with the other dilutions. Under the experimental conditions employed in this study, formocresol revealed its genotoxicity in the more concentrated dilutions, confronting some studies that point to its non-genotoxicity. However, the final dosage of formaldehyde present in these dilutions seems to be higher than those generally used in pulpotomies. It shows that the incorrect use of formocresol is the main responsible for the genotoxic effects reported in the literature.

Artifacts in polarimeters are apparent polarization features which are not real but result from the systematic errors in the polarimeter. The polarization artifacts are different between division of focal plane, spectral, and time modulation polarimeters. Artifacts result from many sources such as source properties, micropolarizer arrays, coatings issues, vibrations, and stress birefringence. A modeling examples of polarization artifacts due to a micro-polarizer array polarimeter is presented.

A systematic method for the design of unsymmetrical optical systems is described. Freeform optical surfaces are constructed by superposition of a conic segment and a polynomial, and successfully applied to design relatively fast wide field-of-view optical systems.