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Dissertations / Theses on the topic 'Optical interferometry'
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1
Arain, Muzamil Arshad. "INTERFEROMETRY-BASED FREE SPACE COMMUNICATION AND INFORMATION PROCESSING." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3304.
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This dissertation studies, analyzes, and experimentally demonstrates the innovative use of interference phenomenon in the field of opto-electronic information processing and optical communications. A number of optical systems using interferometric techniques both in the optical and the electronic domains has been demonstrated in the filed of signal transmission and processing, optical metrology, defense, and physical sensors. Specifically it has been shown that the interference of waves in the form of holography can be exploited to realize a novel optical scanner called Code Multiplexed Optical Scanner (C-MOS). The C-MOS features large aperture, wide scan angles, 3-D beam control, no moving parts, and high beam scanning resolution. A C-MOS based free space optical transceiver for bi-directional communication has also been experimentally demonstrated. For high speed, large bandwidth, and high frequency operation, an optically implemented reconfigurable RF transversal filter design is presented that implements wide range of filtering algorithms. A number of techniques using heterodyne interferometry via acousto-optic device for optical path length measurements have been described. Finally, a whole new class of interferometric sensors for optical metrology and sensing applications is presented. A non-traditional interferometric output signal processing scheme has been developed. Applications include, for example, temperature sensors for harsh environments for a wide temperature range from room temperature to 1000 degree C.Ph.D.
Optics and Photonics
Optics
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Neutze, Richard. "Acceleration and optical interferometry." Thesis, University of Canterbury. Physics, 1995. http://hdl.handle.net/10092/6569.
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The influence of acceleration on a number of physical systems is examined. We present a full relativistic treatment of a simple harmonic oscillator with relativistic velocities. The line element for Schwarzschild geometry is expanded in a set of Cartesian coordinates and is shown to be locally equivalent (neglecting curvature) to the line element of a linearly accelerating frame of reference. We consider the rate of a linearly accelerating quantum mechanical clock and the measurement of frequency by non-inertial observers, requiring this measurement to be of finite duration. These analyses demonstrate the standard measurement hypothesis for accelerating observers only approximates the physical behaviour of these systems.
We derive the output of an optical ring interferometer in a variety of experimental contexts. A full relativistic reanalysis of the modified Laub drag experiment of Sanders and Ezekiel is performed, correcting a number of errors in their work and giving an overall discrepancy between experiment and theory of 1300 ppm. We examine the behaviour of a ring interferometer containing an accelerating glass sample. Our analysis predicts sideband structure will arise when a glass sample is oscillated along one arm of a Mach-Zehnder interferometer and the resulting output Fourier analysed. We also predict a resonant cavity containing a linearly accelerating glass sample will display optical ringing. A rigorous analysis of a ring interferometer with angular acceleration is presented. This predicts a resonant cavity with angular acceleration will also display optical ringing and demonstrates the beat frequency in a ring laser with angular acceleration is the instantaneous Sagnac beat frequency. Finally, we analyse the optical output of a rotating ring laser with one mirror oscillating, predicting sideband structure in spectra obtained from Fourier analysis of the beat between the opposite beams, and the beat between adjacent modes when the laser has multimode operation.
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Wavering, Thomas A. "Optical Path Length Multiplexing of Optical Fiber Sensors." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36037.
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Optical fiber sensor multiplexing reduces cost per sensor by designing a system that minimizes the expensive system components (sources, spectrometers, etc.) needed for a set number of sensors. The market for multiplexed optical sensors is growing as fiberoptic sensors are finding application in automated factories, mines, offshore platforms, air, sea, land, and space vehicles, energy distribution systems, medical patient surveillance systems, etc. Optical path length multiplexing (OPLM) is a modification to traditional white-light interferometry techniques to multiplex extrinsic Fabry-Perot interferometers and optical path length two-mode sensors. Additionally, OPLM techniques can be used to design an optical fiber sensor to detect pressure/force/acceleration and temperature simultaneously at a single point. While power losses and operating range restrictions limit the broadscale applicability of OPLM, it provides a way to easily double or quadruple the number of sensors by modifying the demodulation algorithm. The exciting aspect of OPLM is that no additional hardware is needed to multiplex a few sensors. In this way OPLM works with conventional technology and algorithms to drastically increase their efficiency. [1]Master of Science
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Wang, Zuobin. "New approaches in optical interferometry." Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/76188/.
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This thesis presents two new approaches in optical interferometry: phase difference determination by fringe pattern matching and a spatial phase-shifting interferometry (spatial PSI) algorithm. These two approaches are both theoretically described and experimentally illustrated in this thesis. The method of phase difference determination by fringe pattern matching is capable of detecting the phase difference between two interferograms with subpixel resolution. In this method, the phase curves are obtained from mean-square difference calculations of any two fringe patterns shifted pixel by pixel, and the phase difference between the interferograms can be achieved by linear interpolation or polynomial curve fitting from the phase curves. The signal to noise ratio is significantly improved due to the region-based matching and its effect of averaging noise. The equations derived from the statistical analysis of matching process clearly explain the reason that the larger image patches have a better accuracy in the measurement of phase difference. The three applications of fringe pattern matching, measurement of electrostatic force displacement, displacement measurement based on Youngs experiment, and phase-shifting interferometry with arbitrary phase steps, are also investigated in this thesis. Computer simulation and experimental results have proved that fringe pattern matching is a powerful technique for measuring some basic parameters in optical interferometry such as phase difference, fringe spacing and displacement. In the algorithm of spatial PSI, one fringe pattern is captured by a CCD camera, and the other two shifted fringe patterns with the phase steps of 90oC and 180oc are generated by computer, according to the features of the light intensity distributions and the method of interpolation. The phase is then calculated by a standard three-step algorithm of phase-shifting interferometry. Experimental results have shown that it is a useful approach to spatial PSI.
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Tenefrancia, Sandra L. "Optical pattern comparison by interferometry." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53191.
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By placing two similar input transparencies adjacent to each other in the same plane, and illuminating them with coherent light, it is possible to create parallel fringes that will modulate the composite Fraunhofer diffraction pattern of the two input objects. The power spectrum of the combined inputs, i.e. test and reference signal Fourier transform, is analyzed for regularity of the fringe pattern. The method of interference used on input with small rotational errors and on relatively large displacements of the input does not affect the recognition capabilities of the system. This optical method is useful for making rapid pattern comparisons, where the signal to noise ratio is large.Master of Science
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Kobayashi, Hirokazu. "Geometric phases in optical interferometry." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142564.
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Frater, Eric, and Eric Frater. "Optical Alignment with CGH Phase References." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621452.
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The growing field of high-order aspheric and freeform optical fabrication has inspired the creation of optical surfaces and systems which are difficult to align. Advances in optical alignment technology are critical to fabricating and integrating aspheric components in advanced optical systems. This dissertation explores the field of optical alignment with a computer-generated hologram (CGH) used as a reference. A CGH is a diffractive optic which may be used to create a desired phase profile across a beam of light, project irradiance patterns, or serve as a mask for an incident beam. The alignment methods presented in this dissertation are concerned with the use of a CGH to create reference phase profiles, or "wavefronts" , in a beam. In one application a set of axisymmetric CGH references are co-aligned. Each CGH has also been aligned to an aspheric mirror so the co-alignment of the CGH references is also a co-alignment of the aspheric mirrors. Another application is concerned with aligning an interferometer to test an aspheric mirror surface. The interferometer measures a "null" interference pattern when its wavefront accommodates a known surface profile. In this alignment application the CGH creates wavefronts which accommodate a known set of small spherical reference features at the test surface. An interference null from all the "phase fiducial" reference features indicates an aligned projection of the CGH. The CGH co-alignment method is implemented on a 4-mirror prime focus corrector known as the Hobby-Eberly Telescope Wide Field Corrector (HET WFC). It is shown that this method was very successful for centration alignment of some mirrors, whereas mechanical stability was the hardware limitation for other degrees of freedom. The additional alignment methods used in this project are described in detail and the expected alignment of the HET WFC is reported.The fabrication, characterization and application of spherical phase fiducials is demonstrated in a CGH-corrected Fizeau test prototype. It is shown that these reference features achieve <±1.5µm transverse alignment precision. A pair of phase fiducials is also applied to constrain the clocking and magnification of a projected wavefront. Fabrication and coordinate measurement of the features present the dominant challenges in these demonstrations.
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Ireland, Michael. "Optical interferometry and Mira variable stars /." Connect to full text, 2005. http://hdl.handle.net/2123/721.
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CREATH, KATHERINE. "DIGITAL SPECKLE-PATTERN INTERFEROMETRY (OPTICAL TESTING)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188115.
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A digital speckle-pattern interferometer was built utilizing a 100 x 100 element Reticon diode array interfaced to an HP-9836C desk-top computer. A single-mode optical fiber mounted in the center of the system's aperture stop creates a spherical-wave reference beam. Secondary interference fringes are calculated inside the computer by subtracting speckle patterns before and after a deformation, and squaring this difference. This technique has been shown superior to that of taking the absolute value of the difference. The traditional vibrational observation technique of low-pass filtering a single speckle pattern and squaring the result is emulated in software. It is compared to four other vibration observation techniques. A new technique records the self-interference terms in a reference frame, and subtracts these from the time-averaged vibration data. It provides very good fringe contrast for moderately unstable objects, as well as interferometers which have not been optimized to minimize self-interference terms. The best vibration fringe contrast is obtained by subtracting two time-averaged speckle patterns of a single object resonance. One exposure has a relative π phase-shift between object and reference beams to cancel self-interference terms. This last technique is not real-time; whereas, the new technique is. Double-exposure speckle interferograms are averaged using a technique which utilizes a stepping motor to change the object illumination angle. Results of averaging deformation measurements and double-exposure vibration techniques show a large increase in fringe contrast with an accompanying reduction in speckle noise. Quantitative measurements of object deformations is demonstrated by applying phase-shifting interferometry techniques. A deformation's phase is found by subtracting modulo 2π phases measured for each object state. Phase discontinuities are removed with the aid of noise reduction algorithms. Limitations are low intensity modulation as the phase is shifted, and speckle decorrelation during object deformation. It is shown that 10 waves of object deformation are measurable to λ/10 across the detector array. The double-exposure phase-measurement technique works well and is applicable to many different metrological measurements. To show the versatility of this technique, an optically smooth surface is contoured using two illumination wavelengths.
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Ireland, Michael James. "Optical Interferometry and Mira Variable Stars." Thesis, The University of Sydney, 2005. http://hdl.handle.net/2123/721.
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This thesis describes the development of a red tip/tilt and fringe detection system at the Sydney University Stellar Interferometer (SUSI), modelling the instrumental performance and effects of seeing at SUSI, making observations of Mira variable stars and finally modelling the atmospheres of Mira variables with physically self-consistent models. The new SUSI tip/tilt system is based around a CCD detector and has been successfully used to both track the majority of tip/tilt power in median seeing at an R magnitude of 4.5, and to provide seeing measures for post processing. The new fringe-detection system rapidly scans 33 to 140 $\mu$m in delay and detects the fringes using two avalanche-photodiodes. It has been used to acquire fringe data, provide user feedback and to track the fringe group-delay position. The system visibility (fringe visibility for a point source) and throughput were found to be consistent with models of the SUSI optical beam train. Observations were made of a variety of sources, including the Mira variables R Car and RR Sco, which were observed in two orthogonal polarization states. These measurements were the first successful use of Optical Interferometric Polarimetry (OIP), and enabled scattered light to be separated from bright photospheric flux. Dust scattering was found to originate from a thin shell 2-3 continuum radii from these stars, with an optical depth of 0.1 to 0.2 at 900 nm. Physical models of Mira variables including dust formation were developed, providing consistent explanations for these results as well as many other photometric and interferometric observations.
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Ireland, Michael James. "Optical Interferometry and Mira Variable Stars." University of Sydney. Physics, 2005. http://hdl.handle.net/2123/721.
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This thesis describes the development of a red tip/tilt and fringe detection system at the Sydney University Stellar Interferometer (SUSI), modelling the instrumental performance and effects of seeing at SUSI, making observations of Mira variable stars and finally modelling the atmospheres of Mira variables with physically self-consistent models. The new SUSI tip/tilt system is based around a CCD detector and has been successfully used to both track the majority of tip/tilt power in median seeing at an R magnitude of 4.5, and to provide seeing measures for post processing. The new fringe-detection system rapidly scans 33 to 140 $\mu$m in delay and detects the fringes using two avalanche-photodiodes. It has been used to acquire fringe data, provide user feedback and to track the fringe group-delay position. The system visibility (fringe visibility for a point source) and throughput were found to be consistent with models of the SUSI optical beam train. Observations were made of a variety of sources, including the Mira variables R Car and RR Sco, which were observed in two orthogonal polarization states. These measurements were the first successful use of Optical Interferometric Polarimetry (OIP), and enabled scattered light to be separated from bright photospheric flux. Dust scattering was found to originate from a thin shell 2-3 continuum radii from these stars, with an optical depth of 0.1 to 0.2 at 900 nm. Physical models of Mira variables including dust formation were developed, providing consistent explanations for these results as well as many other photometric and interferometric observations.
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Bhatia, Vikram. "Signal processing techniques for optical fiber sensors using white light interferometry." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09192009-040440/.
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Liu, Xiaojun. "A polarized lateral shearing interferometer and application for on-machine form error measurement of engineering surfaces /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20LIUX.
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George, A. V. "Optical detectors and stellar observations in interferometry." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599357.
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This work describes several self-contained pieces of research which are all linked by their connection with optical interferometry. First is an instrumentational project involving the selection, installation and subsequent testing of second-generation optical detectors for the Cambridge Optical Aperture Synthesis Telescope (COAST). These new detectors extended the magnitude limit of COAST by over a magnitude in the I band, increasing its range of observable astronomical targets and making it the most sensitive separate-element interferometer in this band. Also described were two observational projects. The first was carried out using COAST and was made possible by the improved sensitivity of the instrument after installation of the new detectors. It involved observations of two Be stars, Gamma Cassiopeiae and Zeta Tauri, in a narrow Hα band. Non-zero closure phases were measured in both cases, indicating deviations from axisymmetry in the circumstellar discs of the two stars. The first true map of Gamma Cassiopeiae was presented. The second observational project involved measurements of the proto-planetary nebula IRC+10216 made with the UK InfraRed Telescope (UKIRT), using the interferometric technique of speckle masking to achieve close to diffraction-limited imaging. The results include the first ever K-L map and K-band polarisation map of this source. From these and other observations, we found evidence that the morphology of the complex inner dust cloud differs from the models suggested by most other authors, and the star is completely obscured in both the K and L bands.
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Hee, Michael Richard. "Biological imaging with low coherence optical interferometry." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12928.
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Tan, Ying 1968. "Atom interferometry with phase-masked optical fields." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8289.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2002.Includes bibliographical references (p. 179-180).
We have investigated the use of two-photon induced spin excitation for applications to atom interferometry for lithography and rotation sensing. Our efforts have been grouped into two parts: theoretical study of schemes for nanolithography, and experimental investigation of novel schemes for rotation sensing. For lithography, we have concentrated on designing and studying theoretical models that would allow the creation of two-dimensional lithographic patterns with nanometer scale features. Specifically, We have developed a theoretical model for realizing a two-dimensional interferometer capable of producing periodic structures with a feature size of less than 10 nm. Fundamentally, this process uses the two-photon induced spin excitation for splitting atomic waves. We first extended this model to achieve a large degree of splitting via use of multiple pulses, and then showed how the process can be generalized to two orthogonal dimensions with independent controls. We have also designed a scheme for producing arbitrary two-dimensional features using atom interferometry. This process makes use of a phase mask imprinted on a laser pulse, guiding of atomic waves, and atom interferometry in order to produce any desired pattern, with features that can also be only a few nm's in size. For rotation sensing, we have realized experimentally a novel scheme that opens up a new way of controlling the interferometer contour. It may prove to be very robust for practical applications such as gravity gradiometry as well.
(cont.) This process uses a single optical zone with two counter-propagating optical frequencies. The zone can be compartmented into small sections, and the optical phase of each section can be switched between 0 and n in a variable pattern. We have shown via simulations that a wide range of split-wave contours can be realized, including multiple loops of varying areas. Experimentally, we have demonstrated a preliminary version of this scheme. We have demonstrated the atomic interference via scanning the phase of a part of the optical beam. When realized in conjunction with trapped atoms, this scheme is expected to yield a rotation sensing ability that is comparable to the three-zone Raman interferometer. However, it has the advantage of being robust against angular misalignment and differential light shifts. Furthermore, it opens up the possibility of realizing atomic interferometry with dynamically tunable contours.
by Ying Tan.
Ph.D.
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Blecha, Martin. "Pracoviště pro optickou interferometrii." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217262.
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This thesis is specialized on composition of workplace for experiments flowing from optical interferometry. Here are described laboratory exercise servant for demonstration basic principles of interferometry. In more details is described method measurement of height profile objects with method white light interferometry.
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Yip, Tung Yeung Freddie. "Real time image processing in optical microscopy." HKBU Institutional Repository, 2001. http://repository.hkbu.edu.hk/etd_ra/292.
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Wylde, Clarissa Eileen Kenney, and Clarissa Eileen Kenney Wylde. "The Art of Optical Aberrations." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/624090.
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Art and optics are inseparable. Though seemingly opposite disciplines, the combination of art and optics has significantly impacted both culture and science as they are now known. As history has run its course, in the sciences, arts, and their fruitful combinations, optical aberrations have proved to be a problematic hindrance to progress. In an effort to eradicate aberrations the simple beauty of these aberrational forms has been labeled as undesirable and discarded. Here, rather than approach aberrations as erroneous, these beautiful forms are elevated to be the photographic subject in a new body of work, On the Bright Side. Though many recording methods could be utilized, this work was composed on classic, medium-format, photographic film using white-light, Michelson interferometry. The resulting images are both a representation of the true light rays that interacted on the distorted mirror surfaces (data) and the artist’s compositional eye for what parts of the interferogram are chosen and displayed. A detailed description of the captivating interdisciplinary procedure is documented and presented alongside the final artwork, CCD digital reference images, and deformable mirror contour maps. This alluring marriage between the arts and sciences opens up a heretofore minimally explored aspect of the inextricable art-optics connection. It additionally provides a fascinating new conversation on the importance of light and optics in photographic composition.
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Lee, Woei Ming. "Optical trapping : optical interferometric metrology and nanophotonics." Thesis, St Andrews, 2010. http://hdl.handle.net/10023/882.
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Barman, Sarah Ann. "Measurement of profiled surfaces using polarising optical interferometry." Thesis, King's College London (University of London), 1996. http://eprints.kingston.ac.uk/8943/.
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Scott, Tania Ruth. "The implications of atmospheric seeing for optical interferometry." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624761.
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Black, Jacob A. "Neural Networks For Phase Demodulation In Optical Interferometry." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/93263.
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Neural Networks (NNs) (or 'deep' neural networks (DNNs)) have found great success in many applications across all fields of engineering, and in particular have found recent success in the field of Photonics. In this work we discuss the application of NNs to optical interferometry for the purpose of quantitative phase imaging (QPI). We show that NNs are capable of quantifying the optical pathlength difference in an interferogram with sensitivities that achieve the fundamental limit given by the Cramér-Rao bound (CRB). As an application, we consider a particular QPI technique known as wavelength shifting interferometry (WSI) which obtains the OPL by acquiring multiple interferograms at different, evenly spaced wavenumbers. Traditional phase demodulation algorithms for WSI fail to reach the theoretical OPL sensitivity limit set by the CRB. We have designed NNs which are capable of achieving this bound across a wide range of OPL differences. The NNs are trained on simulated data, and then applied to experimental data. In both simulation and experiment, the NNs outperform the existing analytical demodulation techniques and provide highly sensitive signal demodulation in cases where the analytical approach fails. Thus, NNs provide better performance and more flexibility in the design and use of a WSI system. We expect that the techniques developed in this work can be extended to other two-beam interference based QPI system.M.S.
Neural Networks (NNs) (or 'deep' neural networks (DNNs)) have found great success in many applications across all fields of engineering, and in particular have found recent success in the field of Photonics. In this work we discuss the application of NNs to making so-called 'phase' images of biological cells and tissues (e.g. red blood cells, sperm cells). This is necessary for many biological samples which are transparent under traditional bright field microscopy. We show that NNs are capable of quantifying the phase of these samples to produce images with higher contrast than possible in a typical microscope image. As an example, we introduce a particular phase microscopy system and study the application of NNs to this system. We show that the NNs are capable of providing solutions for this phase in situations where existing analytical techniques fail. The NNs are also capable of making more precise calculations of the phase than the traditional algorithms in many situations where either technique could be used. Therefore, NNs can provide simultaneously higher performance and more flexibility when designing phase microscopy systems.
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Dovale, Alvarez Miguel. "Optical cavities for optical atomic clocks, atom interferometry and gravitational-wave detection." Thesis, University of Birmingham, 2019. http://etheses.bham.ac.uk//id/eprint/8851/.
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It is an extremely exciting time for physics. In the last 100 years we moved from the formulation of Einstein's general relativity to the first direct observation of gravitational waves in late 2015 by the Laser Interferometer Gravitational-wave Observatory (LIGO). In that time we learned to use light to cool atoms to nearly absolute zero temperature, and to use atomic transitions in the microwave and optical regimes to devise the most accurate time and frequency references. We observed the wave-like behaviour of cold atoms in diffraction experiments using the periodic structure of light beams. Exploiting this wave-like behaviour, we constructed atom interferometers which allow us to test and measure gravity in a new scale. All of these experiments have one thing in common, from LIGO's giant 4 km arms, to the transportable atomic clocks sent to space, they all make use of a device that has become essential in many areas of science and technology: the Fabry-Perot optical cavity. This thesis delves deeply into the application of optical cavities at the forefront of experimental physics, and it is divided into three parts, each pertaining to a different field where optical cavities are a key technology.
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Michie, Andrew M. "Sensing and interferometry, including design and characterisation of special optical fibres." Physics, 2009. http://hdl.handle.net/2123/5784.
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Doctor of PhiliosophyThis thesis presents my work in the area of optical fibre sensing, and optical fibre design and characterisation along with the interferometric and signal processing techniques that were developed along the way.
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Michie, Andrew M. "Sensing and interferometry, including design and characterisation of special optical fibres." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/5784.
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This thesis presents my work in the area of optical fibre sensing, and optical fibre design and characterisation along with the interferometric and signal processing techniques that were developed along the way.
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Bhagwandin, Bryon D. "An integrated optical microcalorimeter /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/7996.
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de, Barros Correia Kyotoku Bernardo. "Applications of optical coherence tomography and advances into a photonic integrated device." Universidade Federal de Pernambuco, 2011. https://repositorio.ufpe.br/handle/123456789/6125.
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Previous issue date: 2011Conselho Nacional de Desenvolvimento Científico e Tecnológico
Tomografia por coerência óptica (OCT) é uma técnica de imageamento não invasiva que usa radiação infravermelho para sondar alguns milímetros the profundidade de um alvo com um resolução de poucos micrômetros. Aqui, nós expomos a base teórica para entender a técnica. O texto cobre as duas variedades de OCT domínio temporal e domínio da frequência e descreve três aplicações da técnica em odontologia: a) Um na avalição the propagação rachaduras em polímeros reforçado com fibra usado em restauração dental; b) O imageamento da sobra de dentina e cavidade pulpar após excavação da dentina, com o propósito de medir a espessura da dentina, e c) uma avaliação clínica da integridade de restaurações dentais. Em todas essa aplicações, OCT gerou imagens marcantes e forneceu informações semiquatitativas sobre a estrura dentária. Com o objetivo de desenvolver um sistema de tomografia óptica integrada em um chip. Nós expomos a base teórica da plataforma de fotônica integrada. Após uma revisão literária, nós descobrimos que não existe espectrômetro integrado com a especificações necessárias para uso em OCT. Nós, então, desenvolvemos um espectrômetro com a características necessárias. Isso foi possível devido a uma nova arquitetura de espectrômetro baseada na combinação de um ressoador em anel e um espectrômetro de grade de difração
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Tearney, Guillermo J. "Optical characterization of human tissues using low coherence interferometry." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11864.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 84-85).
by Guillermo James Tearney.
M.S.
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CHENG, YEOU-YEN. "MULTIPLE-WAVELENGTH PHASE SHIFTING INTERFEROMETRY (OPTICAL-TESTING, ASPHERIC SURFACE)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187928.
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The problems of combining ideas of phase shifting interferometry (PSI) and synthetic-wavelength techniques to extend the phase measurement range of conventional single-wavelength PSI are investigated. This combination of PSI and synthetic-wavelengths gives multiple-wavelength phase-shifting interferometry the advantages of: (1) larger phase measurement range and (2) higher accuracy of phase measurement. Advantages, error sources, and limitations of single-wavelength PSI are discussed. Some practical methods to calibrate the piezoelectric transducer (PZT), used to phase shift the reference beam, are presented with experimental results. Two methods of two-wavelength PSI are used to solve the 2π ambiguity problem of single-wavelength PSI. For the first method, two sets of phase data (with 2π ambiguities) for shorter wavelengths are calculated and stored in the computer which calculates the new phase data for the equivalent-wavelength λ(eq). The "error magnification effect," which reduces the measurement precision of the first method, is then investigated. The second, more accurate method, uses the results of the first method as a reference to correct the 2π ambiguities in the single-wavelength phase data. Experimental results are included to confirm theoretical predictions. The enhancement of two-wavelength PSI is investigated, and requires the phase data of a third wavelength. Experiments are performed to verify the capability of multiple-wavelength PSI. For the wavefront being measured, the difference of the optical-path-difference (OPD) between adjacent pixels is as large as 3.3 waves. After temporal averaging of five sets of data, the repeatability of the measurement is better than 2.5 nm (0.0025%) rms (λ = 632.8 nm). This work concludes with recommendations for future work that should make the MWLPSI a more practical technique for the testing of steep aspheric surfaces.
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Sawyer, Nicolas B. E. "Novel optical surface metrology methods." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287239.
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Cropanese, Frank C. "Synthesis of low k1 projection lithography utilizing interferometry /." Link to online version, 2005. https://ritdml.rit.edu/dspace/handle/1850/1235.
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Robinson, Dirk J. "Optically relayed push-pull velocity interferometry resolved in time and position." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Spring2005/d%5Frobinson%5F050605.pdf.
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Czajkowski, J. (Jakub). "Optical coherence tomography as a characterization method in printed electronics." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526202600.
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Abstract This Thesis proposes and describes the use of optical coherence tomography (OCT) as a non-contact and non-destructive characterization technique for printed electronics. It is based on and includes the first published results of such an application of the OCT technique. Several different types of structures were studied to evaluate the feasibility of the application. The measurement data was used to define the surface topography, physical dimensions of the specimen features, and to evaluate the ability to characterize multi-layered and multi-material structures. Presented OCT measurements were done for: screen-printed conductive and insulating structures, microfluidic channels, microscopy glass and organic field effect transistors (OFET), both coated with polymer, and inkjet-printed colour filters. A novel approach to encapsulation inspection was presented. The results show that OCT could be used for full volumetric and non-destructive characterization of the 1-to-2-µm-thin protective layers used in organic and printed electronics. The measurements presented in the Thesis were done using OCT devices in time and in spectral domains. Despite the focus on studying the application of the technique, as a result of observations and limitations of the existing equipment, a new type of OCT device has been developed. A high data acquisition rate of the spectrometer-based systems (SD-OCT) was combined with a broadband supercontinuum light source, used so far mainly in the time-domain (TD-OCT), to enable the sub-micron-resolution spectral domain optical coherence tomography (SMR SD-OCT). The supercontinuum generation effects with virtually white probing light and enables not only superior resolution, but also, e.g., true-colour OCT imaging. The measurements performed on the inkjet-printed colour filters confirm that despite the absorptive properties of the materials, characterization of the few-microns-thin ink layers is possible using visible range of the electromagnetic spectrum and spectral domain OCT. The study shows the potential and versatility of OCT in the printed electronics characterization. In addition, the Thesis discusses further development of the technique, needed to fully match the challenging requirements of the on-line quality inspectionTiivistelmä Väitöstyössä sovelletaan optista koherenssitomografiaa (OCT) painetun elektroniikan kontaktittomaan ja kohdetta rikkomattomaan karakterisointiin. Väitöstyö pohjautuu tuloksiin, joissa OCT-tekniikkaa on hyödynnetty ensimmäistä kertaa painettavan elektroniikan rakenteen karakterisoinnissa. Tekniikan soveltuvuutta tutkittiin mittaamalla useita erilaisia näytteitä. Mitattua dataa käytettiin pinnan topografian ja näytteen dimensioiden määritykseen. Lisäksi tutkittiin tekniikan soveltuvuutta monikerrosrakenteiden ja useista eri materiaaleista koostuvien näytteiden mittaukseen. OCT-mittaukset tehtiin seuraaville näytteille; silkkipainetuille johteille ja eristeille, mikrokanaville, polymeerillä päällystetyille mikroskooppilaseille ja orgaanisista aineista valmistettu kanavatransistoreille (OFET) sekä mustesuihkutulostimella valmistetuille värisuodattimille. Orgaaniset materiaalit ja painettava elektroniikka suojataan yleensä koteloinnilla. Tässä väitöstyössä esitellään uusi menetelmä koteloinnin tarkastukseen. Tulokset osoittavat, että OCT-tekniikkaa voidaan hyödyntää 1-2 mikrometrin paksuisen eristekerroksen volumetrisen rakenteen karakterisointiin kohdetta rikkomatta. Tässä väitöstyössä tehdyt mittaukset tehtiin aika- ja spektritason OCT-laitteilla. Huolimatta siitä, että väitöskirjatutkimus keskittyi tekniikan uusiin sovelluksiin, väitöstyössä havaittiin käytettävissä olevien laitteiden puutteellisuudet, jonka vuoksi myös uusi OCT-laite kehitettiin. Spektrometriin pohjautuvan OCT-systeemin (SD-OCT) nopeus yhdistettiin laajakaistaisen supercontinuum valonlähteen kanssa, jota on käytetty aikaisemmin käytännössä vain aikatason OCT-laitteissa (TD-OCT). Laajakaistainen valonlähde mahdollistaa jopa alle mikrometrin syvyyssuuntaisen resoluution. Supercontinuum valonlähde tuottaa käytännöllisesti katsoen valkoista valoa, joka mahdollistaa sekä erinomaisen tarkkuuden, että objektin luonnollisen värin mittaamisen. Mittaustulokset värisuodattimilla osoittavat, että vaikka suodattimissa käytetyt materiaalit absorpoivat spektritason OCT:ssa hyödynnettyä näkyvän aallonpituusalueen spektriä, tekniikalla on mahdollista mitata muutamien mikrojen paksuisia värisuodatinkalvoja. Väitöstutkimus osoittaa OCT-tekniikan monipuolisuuden ja mahdollisuudet painettavan elektroniikan karakterisoinnissa. Lisäksi väitöstyö käsittelee tekniikan jatkokehitystä, jotta se voisi vastata mahdollisimman hyvin reaaliaikaisen laadunvalvonnan tarpeisiin
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Karatzas, L. S. "On the development of an optical force-feedback microphone." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259893.
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Galda, Martin. "Optický tribometr pro studium mazacích filmů při užití tekutých plynů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230604.
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Aim of this thesis is the design of experimental equipment for studying the formation of lubricating films in contacts lubricated machine parts Liquid gases with the following parameters: experimental device to operate on the principle of optical tribometer, the design will be modified so that it can be used to deleting contacts liquid gases.
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Hodgkinson, Jane. "Photoacoustic and photothermal detection of trace compounds in water." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244982.
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Woodruff, Henry Christian A. "Optical and infrared aperture masking interferometry of mira variable stars." Thesis, The University of Sydney, 2009. https://hdl.handle.net/2123/28457.
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1.1 A Brief History of Interferometry
The theoretical angular resolution of a telescope with perfect optics is proportional to the diameter of the aperture. A 10 m telescope (e.g. the Keck I telescope on Mauna Kea, Hawaii) in the
visible range of light (x1 z 500 nm) could theoretically achieve resolutions of 12 milliarcseconds
(mas). It might seem that in order to increase angular resolution, building bigger telescopes
would be the only reasonable thing to do!
In reality, the comfortable blanket of the Earth’s atmosphere has proven to be quite a show
stopper for high-resolution observations. As telescopes with greater and greater diameters were
built, astronomers realised that the angular resolution of any given telescope was limited to ~l”
by atmospheric turbulence, corresponding to the resolution obtainable from a 10-20 cm aperture.
In view of this restriction, Simon Newcomb, founder and first president of the American Astronomical Society, reportedly said in 1888 “We are probably nearing the limit of all we can know
about astronomy” (Green & Lomask 1970).
Nonetheless, it is clearly necessary to obtain better angular resolution to study the universe.
All stars (apart from the Sun) have angular diameters that cannot be resolved with a 20 cm tele—
scope. It was some time after Thomas Young’s double-slit experiment in 1803 proved the wavelike
nature of light that a physicist had the idea to use this property for the advancement of
astronomy. Fizeau (1868) was the first to suggest that light from astronomical sources could
also be made to form interference patterns. As in Young’s double-slit experiment, the size of the
source of light affects the contrast of the interference fringes. The double slit became a mask
with two sub-apertures in front of the telescope’s main aperture, and astronomical interferometry
was born.
Forty years after the foundations for stellar interferometry had been laid, Michelson & Pease
(1921) successfully measured the angular diameter of a Ori (Betelgeuse), using interference
fringes from a 6m baseline two-aperture interferometer mounted on the 100 inch telescope on
Mt. Wilson, California, USA.
The angular resolution of interferometric observations increases with increasing baseline
lengths and decreasing wavelengths, but so does the demand on the precision of the instrumental
set-up. Atmospheric effects (“seeing”) which degraded fringe contrast, also dictated short expo—
sure times and the need for active electronic control systems. So optical and near—infrared (NIR)
interferometry had to bear the limits imposed by technology and was limited to bright, nearby
stars. In the meantime, radio astronomy made advances in interferometry and aperture synthesis.
Groups led by Martin Ryle at Cambridge and Bernard Mills at the University of Sydney were the
first to apply interferometric techniques to radio astronomy.
As instrumentation advanced (CCD technology, laser metrology, infrared detectors, Adaptive
Optics, etc.), and the angular resolution of stellar observations increased, so did the demands
on theoretical models. These are hard-pressed to cope with the vast amount of constraints that
observations in multiple wavelengths deliver today.
In this thesis I apply the latest developments in astronomical Fizeau interferometry, namely
non-redundant aperture masking. Results from observations of Mira stars with the aperture masking experiment at the Keck I telescope are reported in Chapters 2 and 3. I also describe the
ZORAO and LAMP experiments, both of which use Low Light Level CCDs, Adaptive Optics
systems and non-redundant masking (Chapters 4, 5 and 6). Experimental results from LAMP are
presented which resolve the Mira variable R Cas.
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Tamate, Shuhei. "Geometry of weak measurements and its application to optical interferometry." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174946.
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Alarousu, E. (Erkki). "Low coherence interferometry and optical coherence tomography in paper measurements." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514282140.
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Abstract
This thesis describes the application of Low Coherence Interferometry (LCI) and Optical Coherence Tomography (OCT) in paper measurements. The developed measurement system is a combination of a profilometer and a tomographic imaging device, which makes the construction versatile and applicable in several paper measurement applications. The developed system was first used to measure the surface structure of paper.
Different grades of paper were selected to provide maximum variation in surface structure. The results show that the developed system is capable of measuring grades of paper from rough base paper to highly coated photo printing paper.
To evaluate the developed system in surface characterization, the roughness parameters of five laboratory-made paper samples measured with the developed system and with a commercial optical profilometer were compared. A linear correlation was found with roughness parameters Ra and Rq.
Next, the surface quality of paper was evaluated using LCI, a Diffractive Optical Element Based Glossmeter (DOG), and a commercial glossmeter. The results show linear correlation between Ra and gloss measured with the commercial glossmeter. The roughness Ra and averaged gloss measured with the DOG didn't give such a correlation, but a combination of these techniques provided local properties of gloss and surface structure, which can be used to evaluate the local surface properties of paper.
In the next study, determination of the filler content of paper using OCT is discussed. The measurement results show clear correspondence of the slope of the averaged logarithmic fringe signal envelope and the filler content.
The last studies focus on 2D and 3D imaging of paper using OCT and begin with imaging of a self-made wood fiber network. The visibility of the fibers was clear. Next, several refractive index matcing agents are studied by means of light transmittance and OCT measurements to find the best possible agent for enhancing the imaging depth of OCT in paper. Benzyl alcohol was found to have the best possible combination of optical, evaporation, and sorption characteristics, and it is applied in 2D and 3D visualizations of copy paper.
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Campagnolo, Lucie. "Optical feedback interferometry sensing technique for flow measurements in microchannels." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2013. http://tel.archives-ouvertes.fr/tel-01068169.
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Le phénomène d'interférométrie par réinjection optique, ou effet self-mixing dans un laser permet de concevoir des capteurs non-invasifs, auto-alignés, ne nécessitant que peu d'éléments optiques et simples à implémenter. Ce type de capteur permet de mesurer avec la précision propre à l'interférométrie laser le déplacement, la vitesse ou la position de cibles dite coopératives (cibles réfléchissantes ou fortement diffusantes). Dans cette étude, ce type de capteurs est appliqué à la mesure de profil d'écoulement des fluides dans des microcanaux. Le faible coût et la polyvalence des capteurs à réinjection optique sont d'un grand intérêt dans l'industrie biomédicale et chimique, ainsi que pour la recherche en mécanique des fluides. Dans un premier temps, et en se basant sur les études réalisées dans des macro-canaux, nous avons proposé un modèle d'interferométrie par réinjection optique dans une diode laser lorsque la cible est constitué de particules en mouvement, en suspension dans un liquide. A partir de ce modèle, nous avons étudié expérimentalement l'impact du volume de mesure ainsi que du type de particules (taille et concentration) sur le signal mesuré. Nous avons ensuite proposé des méthodes de traitement du signal permettant de calculer le calcul du débit du fluide, ainsi que sous certaines conditions identifiées, la vitesse locale en tout point d'un microcanal. Ces études préliminaires nous ont permis de reconstruire le profil d'écoulement de différents liquides dans des canaux de 320µm de diamètre. Enfin, nous avons comparé les performances du capteur développé dans cette thèse avec un capteur basé sur la technique du Dual-Slit, technique déjà validée pour la microfluidique, en mesurant le profil d'écoulement dans un canal à section rectangulaire de 100x20µm.
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Luke, David George. "Broadband optical fibre interferometry for strain measurement in composite materials." Thesis, Heriot-Watt University, 1997. http://hdl.handle.net/10399/655.
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Chan, Tsang Hung. "Digital signal processing in optical fibre digital speckle pattern interferometry." HKBU Institutional Repository, 1996. http://repository.hkbu.edu.hk/etd_ra/269.
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Mukhtar, Husneni. "Development of compensated immersion 3D optical profiler based on interferometry." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAD017/document.
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La CSI (Coherence Scanning Interferometry) ou la WLSI (White Light Scanning Interferometry) est une technique d'imagerie optique bien établie pour mesurer la rugosité de surface et la forme des surfaces microscopiques. Les avantages sont la sensibilité axiale nanométrique, un large champ de vision (des centaines de μm à plusieurs mm) et la vitesse de mesure (quelques secondes à quelques minutes). La technique est basée sur l'interférométrie optique avec une configuration de Linnik très difficile à ajuster mais elle présente plusieurs avantages: des objectifs d'ouverture numérique plus élevés pour améliorer la résolution spatiale; longue distance de travail, car il n'y a aucun besoin de l'un des composants devant l'objectif; une configuration de mode de lumière polarisée; franges contrastées en raison de la possibilité de modifier les voies optiques et les intensités des deux bras indépendamment. Alors que l'utilisation d'un objectif d'immersion dans l'eau présente les avantages suivants: éviter les problèmes liés à l'ajustement entre la formation des franges et le plan de formation de l'image; et pour minimiser la différence de dispersion entre les bras de l'interféromètre. Afin de pouvoir mesurer en mode eau et d'obtenir des échantillons à haute résolution latérale de types chimiques et biologiques, plusieurs défis doivent être surmontés tels que l'équilibrage de l'OPD sur les deux bras; trouver et ajuster les bonnes franges de contraste; trouver et adapter une compensation adéquate de l'eau dans le bras de référence horizontal pour faire fonctionner un système dans l'eauCoherence Scanning Interferometry (CSI) or White Light Scanning Interferometry (WLSI) is a well-established optical imaging technique for measuring the surface roughness and the shape of microscopic surfaces. The advantages are the nanometric axial sensitivity, a wide field of view (hundreds of μm to several mm) and the measurement speed (a few seconds to a few minutes). The technique is based on optical interferometry with a Linnik configuration which very difficult to adjust but it offers several advantages: higher numerical aperture objectives to improve spatial resolution; long working distance, because there is no need for any of the components in front of the lens; a polarized light mode configuration; contrasting fringes because of the possibility of modifying the optical pathways and the intensities of the two arms independently. While the use of a water-immersion objective gives the following advantages: to avoid the problems related to the adjustment between the formation of the fringes and the plane of formation of the image; and to minimize the difference in dispersion between the arms of the interferometer. In order to be able to measure in water mode and to obtain high lateral resolution samples of chemical and biological types, several challenges must be overcome such as balancing the OPD on both arms; finding and adjusting the good contrast fringes; finding and adapting a suitable water compensation of water in horizontal reference arm to operate a system in water
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Holmes, R. D. "Coherent optical detection techniques in surface metrology." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294698.
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Wang, Jianmin. "A study of optical and opto-electronic techniques for nondestructive testing." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1495.
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Charles, Ned. "Design of Three-Dimensional, Path Length Matched Optical Waveguides." Thesis, The University of Sydney, 2012. http://hdl.handle.net/2123/10282.
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A method for designing physically path length matched, three-dimensional photonic circuits is described. These waveguides, with arbitrary endpoints, were fabricated via the femtosecond laser direct-write technique. The focus is specifically on the case where all waveguides are uniquely routed from the input to output; a problem which has not been addressed to date and allows for the waveguides to be used in interferometric measurements. Two iterative design methods were created for path length matched waveguides with adequate separation in three dimensions and minimized curvature. These algorithms could be used to calculate predicted radius of curvature, bend and transition loss in the waveguides, with results confirmed by computer simulation methods. Demonstrations via interferometric methods show that the fabricated circuits were indeed optically path length matched to within 45 μm which is well within the coherence length required for typical applications, includi ng astronomical measurements.
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Kimbrough, Bradley Trent. "Path Matched Vibration Insensitive Fizeau Interferometer." Diss., Tucson, Arizona : University of Arizona, 2006. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1444%5F1%5Fm.pdf&type=application/pdf.
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Cavan, Alicia Emily. "Digital Holographic Interferometry for Radiation Dosimetry." Thesis, University of Canterbury. Physics and Astronomy, 2015. http://hdl.handle.net/10092/10465.
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A novel optical calorimetry approach is proposed for the dosimetry of therapeutic radiation,
based on the optical technique of Digital Holographic Interferometry (DHI). This detector
determines the radiation absorbed dose to water by measurement of the refractive index variations
arising from radiation induced temperature increases. The output consists of a time
series of high resolution, two dimensional images of the spatial distribution of the projected
dose map across the water sample. This absorbed dose to water is measured directly, independently
of radiation type, dose rate and energy, and without perturbation of the beam.
These are key features which make DHI a promising technique for radiation dosimetry.
A prototype DHI detector was developed, with the aim of providing proof-of-principle of the
approach. The detector consists of an optical laser interferometer based on a lensless Fourier
transform digital holography (LFTDH) system, and the associated mathematical reconstruction
of the absorbed dose. The conceptual basis was introduced, and a full framework was
established for the measurement and analysis of the results. Methods were developed for
mathematical correction of the distortions introduced by heat di usion within the system.
Pilot studies of the dosimetry of a high dose rate Ir-192 brachytherapy source and a small
eld proton beam were conducted in order to investigate the dosimetric potential of the technique.
Results were validated against independent models of the expected radiation dose
distributions.
Initial measurements of absorbed dose demonstrated the ability of the DHI detector to resolve
the minuscule temperature changes produced by radiation in water to within experimental
uncertainty. Spatial resolution of approximately 0.03 mm/pixel was achieved, and the dose
distribution around the brachytherapy source was accurately measured for short irradiation
times, to within the experimental uncertainty. The experimental noise for the prototype
detector was relatively large and combined with the occurrence of heat di usion, means that
the method is predominantly suitable for high dose rate applications.
The initial proof-of-principle results con rm that DHI dosimetry is a promising technique,
with a range of potential bene ts. Further development of the technique is warranted, to
improve on the limitations of the current prototype. A comprehensive analysis of the system
was conducted to determine key requirements for future development of the DHI detector
to be a useful contribution to the dosimetric toolbox of a range of current and emerging applications.
The sources of measurement uncertainty are considered, and methods suggested
to mitigate these. Improvement of the signal-to-noise ratio, and further development of the
heat transport corrections for high dose gradient regions are key areas of focus highlighted
for future development.
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Hodges, Ping Y. "Electro-optical Properties of Ultra-Thin Organic Films." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32070.
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Electro-optical properties of thin film are of great interest owing to the perpetual demand for miniaturization and higher speed devices for communication, electronic, and biomedical applications. The thickness of polymer films developed for these applications has decreased dramatically making interfacial effects significant. It is well documented that, in submicron thickness range, both film/substrate & film/air interface are critical. In this study, we probe the dynamics of electro-optical polymer thin films in the sub-micron thickness regime to understand interfacial effects. The polymer chain dynamics of Polypropylene oxide (PPO) under electric field are investigated in this study. The effects of electric field strength, frequency, and polymer molecular weight on the polymer chain dynamics under electric field are studied. Experimental results show that PPO exhibits both piezoelectric and electrorestrictive effects at significantly high frequencies (101kHz range). Conventional organic materials are responsive only at frequencies in <1kHz range. A high signal-to-noise ratio differential interferometry is designed to quantitatively study the effects of film thickness, electric field frequency and amplitude on the dynamic properties of PPO thin films ranging from 30 nm to 400 nm. The interferometer can concurrently monitor the index of refraction, thickness change of polymer films, and birefringence due to the applied electrical field.Master of Science