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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A balloon-borne interferometer for infra-red aeronomy / by Keith Harwood.

Harwood, Keith January 1972 (has links)
139 leaves : ill., photos ; 28 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics, 1972
12

Random phase shift interferometer

Doloca, Nicolae Radu January 2008 (has links)
Zugl.: Braunschweig, Techn. Univ., Diss., 2008
13

Phononeninduzierte Röntgenquantenschwebungen

Rode, Gerald. January 2000 (has links)
Ulm, Univ., Diss., 2000.
14

Ein Michelson-Interferometer für Röntgenstrahlen

Nußhardt, Michael. Unknown Date (has links)
Universiẗat, Diss., 2000--Dortmund. / Dateiformat: PDF.
15

Construção de um interferômetro de Bath para análise do comportamento da superfície de vidros usados na confecção de espelhos côncavos

Bacha, Marcelo Gomes [UNESP] 14 February 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-14Bitstream added on 2014-06-13T18:40:18Z : No. of bitstreams: 1 bacha_mg_me_bauru.pdf: 1693863 bytes, checksum: 92fb550b499e59844a5bcd48f540291b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foi comparado o desempenho dos dois vidros mais utilizados na fabricação de espelhos côncavos de médio porte (até 25 cmde diâmetro). Os materiais analisados foram vidros nos sistema soda-cálcio e boro-silicato. Os espelhos foram comparados em relação a dilatação térmica e a sua rigidez elástica, tendo como principal objetivo avaliar qual vidro deformaria menos sua superfície mantendo sua qualidade óptica em relação a variação da tmmperatura e do seu próprio peso. Para tanto, a análise foi realizada através dos resultados captados pelo interferômetro de Bath, montado no Observatório Didático de Astronomia Lionel José Andriatto, da Faculdade de Ciências, UNESP, Bauru. Como amostras para o trabalho, foram utilizados espelhos primários côncavos de telescópios Newtonianos construídos com os vidros analisados. As medidas foram inspiradas nas condições que os espelhos sofrem durante o seu uso, ambientes com temperatura variável e efeitos causados pela gravidade quando os espelhos estão na posição vertical. Ainda para testar a rigidez elástica dos vidros, os espelhos foram apoiados apenas pelas bordas. Os parâmetros utilizados para verificar o desempenho da superfície dos espelhos, foram deformados na curvatura, somatória das deformações na frente de onda e fator Strehl. Utilizando as franjas de interforometrias que foram associadas aos polinômios de Zernike por análise computacional, foi possível realizar o levantamento dos defeitos na superfície com precisão de nanômetros. Através dos dados obtidos no trabalho foi possível confirmar o desempenho superior do espelho feito com vidro de boro-silicato, esse material se apresentou mais estável em todas as medidas realizadas, sofrendo deformações na superfície menores que o vidro soda-cálcico / This work aims to compare the performance of two types of glasses, which are the most used in the manufacture of medium sized concave mirrors (up to 25 cm of diameter). The investigated materials were soda-lime and borosilicate glasses. The mirrors were compared concerning their thermal expansion and their elastic rigidity, and the main goal was to find out which glass would have a less deformed surface, main goal was to find out which glass would have a less deformed surface, maintaining the optical quality, under temperature variation and the mirror weight itself. In order to accomplish that, an analysis was carried out based on data collected by the Bath interferometer, built in the Didactic Astronomy Observatory Lionel José Andriatto. As samples for this work, it was used concave primary mirrors of Newtonian telescopes built with these glasses. The measurements were based on conditions that mirrors are exposed during their regular use, such as variable temperature environments and gravity effects when the mirrors are kept upright. Besides, to test the rigidity, the glass mirrors were held only by the edges. To check the performance, the used parameters were deformation in curvature, the sum of the wavefront deformations and Strehl factor. Interometer fringes were associated with Zernikes polynomials by computational analyses, making possible a survey of defects on the surface with nanometer accuracy. Using data obtained in this study, it was possible to confirm the superior performance of the mirror built with borosilicate glass, which was the most stable sample in all the measurements, presenting less surface deformations when compared with the sodalime glass
16

An investigation of optical radar and low coherence interferometry detection of precancerous tissue

Bamford, Karl J. January 2000 (has links)
No description available.
17

Remote sounding of the atmosphere by high-resolution spectroscopy

Jay, Victoria Louise January 2000 (has links)
No description available.
18

The Promotion of the Performance Based on Dual Sagnac Interferometer Hydrophones

Chen, Han-Yang 08 August 2006 (has links)
An interferometer is used for phase detection. Thus, the hydrophone which is based on interferometric optic fiber sensor has extremely high sensitivity. Sagnac interferometric hydrophone has low noise of marine environment, which is more suitably used to detect underwater acoustic signal than that of a Mach-Zehnder interferometer. In this paper, a configuration of dual Sagnac interferometer was proposed. The mathematical model was derived and analyzed. The fiber optic sensor head contains mandrel type and planar one. The acoustic window are made of silicon rubbers. It was should that we can increase their sensitivities by increase number of wrapping fiber coils. In our experiment, the result shows that among all the mandrel sensor heads, the most highest dynamic range is up to 37.6¡Ó1.4 dB, and its sensitivity is -223.3¡Ó1.7 dB re V/1µPa ; while the dynamic range of the planar sensor head is 42.1¡Ó1.5 dB, and its sensitivity is -213.8¡Ó1.3 dB re V/1µPa¡C As for the configuration of the optical interferometers, the intensity of the dual Sagnac interferometer is 20 dB larger than its Sagnac counterpart. Its dynamic range is above 66 dB, which is 24 dB larger than that of the Sagnac interferometer with the sensitivity of -192.0 dB re V/1µPa. In addition, by using software simulation to design optimal lengths of delay fibers , we can increase interferometer¡¦s the dynamic range of underwater acoustic detection. This paper verify that, by means of adjusting the length of these two delay fibers, we can actually increase the dynamic range of acoustic signal detection.
19

Fiber-Optic Distributed Sensor System for the Detection of the Leakage of Gas Pipelines

Meng-Tsan, Tsai 10 July 2002 (has links)
This system is designed to detect the leakage position of gas pipelines. By Sagnac interferometric theory, we develop the hybrid configuration of Mach-Zehnder and Sagnac Interferometer. It contains the properties of Sagnac Interferometer and it is easy to spread the fiber on the pipelines. When the leakage happened, it will generate the sound signal. This kind of sound pressure will make the total fiber length changed, and hence it will make phase difference. By getting the phase difference, we will get the information of leakage position. After a series of experiments, we prove our theory is correct and we can get an accurate position. The Dynamic range of the system is more than 75 dB. The smallest signal that can be detected is about 3.345x10^-4(rad/Hz).
20

Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy

Tumlinson, Alexandre Rex January 2007 (has links)
In vivo monitoring of mouse models of colon cancer promises to reduce the cost of research by improving sacrifice timing and allowing serial studies that observe the progression of disease and drug efficacy in a relatively small set of animals. Optical coherence tomography (OCT) is an optical analog of ultrasound imaging, capable of minimally-invasive mapping of light scatter intensity up to 2 mm deep in tissue. In this work, factors limiting resolution in OCT were examined and devices were created and applied to mouse colon imaging that extended the state-of-the-art in endoscopic ultrahigh-resolution OCT. First, axial chromatic aberration of the objective optics acts as a spectral filter in the sample arm limiting the effective bandwidth of the system. An achromatized endoscope design was demonstrated that achieved axial resolution of 2.3 mum in tissue and 4.4 mum lateral spot diameter with 101 dB sensitivity when interfaced with a time domain OCT system utilizing a 10-femtosecond laser (bandwidth=150 nm FWHM, center wavelength=800 nm). Second, dispersion matching between the sample and reference arms presents the practical resolution limit to endoscopic implementations including a separate, fiber-based reference arm. A second endoscope incorporated the reference arm into the tip of the endoscope using a novel custom beamsplitter prism and achieved 2.4 mum axial resolution in tissue without adjustments for pathlength or dispersion matching when interfaced with a spectrometer-based frequency domain OCT system and a similar laser. Third, non-linear dispersion of the sample media with respect to wavelength causes distortion and broadening of the axial point spread function when data are sampled uniformly in optical frequency. An experiment was performed on high dispersion glass to demonstrate that dispersion artifact free imaging can be achieved without post process corrections if the samples are acquired at equal intervals of media index of refraction divided by vacuum wavelength. Finally, other microscopic modalities that depend on tissue scatter intensity are used to find the origins of scatter in the mouse colonic mucosa. These observations are used to explain unexpected features found in ultrahigh-resolution tomograms collected with the two endoscopes presented.

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