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1
Munro, Peter Robert Thomas. "Application of numerical methods to high numerical aperture imaging." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427816.
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Flagello, Donis George. "High numerical aperture imaging in homogeneous thin films." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186395.
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This dissertation investigates imaging phenomena by lenses of high relative numerical aperture (NA) in the first layer of a homogeneous thin film stack. The imaging is described by a high NA model that combines elements of vector imaging theory with traditional thin-film optics. Various examples are studied with an emphasis on analyzing the polarization effects of the illumination. Experiments are shown that verify aspects of the model. A brief review of the development of high NA imaging theory is given. The use of the Debye approximation dominates most of the previous work. Investigation of imaging in thin films has been limited to the area of micro-photolithography, where verification studies are done in photoresist. High NA imaging in films is described in terms of matrix formalism. The image is based on the Debye approach in which the vector field is characterized as a plane wave decomposition for each Cartesian component of the electric field, E. This is used to describe propagation from object to entrance pupil, from entrance pupil to exit pupil, and from exit pupil to thin-film stack. If the first film of the stack is located at or near focus, the amplitude and phase of each plane wave, weighted by factors due to polarization, aberration and object diffraction, are used as input into thin-film equations to calculate the local field volume. The image distribution within the film is described by the absorbed electric energy distribution, which is proportional to |E|². The overall effect of the film is shown to significantly reduce vector effects and asymmetries in the image. This is mainly due to the reduction of NA in the film by refraction. The image of a tri-bar object with an extreme NA of 0.95 is simulated. The differences between two orthogonal polarizations are shown to be small. This is attributed to the large contribution due to the central zone of the pupil. The behavior is shown to be similar to three-beam interference. Modification of this simulation with a annular pupil results in image behavior that is very similar to two-beam interference with increased image differences between two polarizations. Two-beam and three-beam interference is shown to be derived from the general imaging equation, resulting in concise analytic vector equations. Experimental verification in photoresist film is shown using a cross-sectioning technique that highlights the image distribution. Structural artifacts within the simulated image are identified in experimental scanning electron microscope photographs. Large differences are seen between S and P polarized illumination.
3
O'Connor, Arthur Bruce 1963. "Polarization properties of high numerical aperture holographic optical elements." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277172.
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The polarization dependent diffraction efficiency and imaging properties of high numerical aperture (N.A.) holographic optical elements (HOEs) were investigated to determine the suitability of these elements for magneto-optic data storage head applications. Two-wave first-order coupled wave theory was combined with a local planar grating model to determine the s and p-polarization diffraction efficiency characteristics of these HOEs. Experimental results for 0.55 N.A. focusing HOEs fabricated in silver halide photographic emulsions and dichromated gelatin films demonstrated that the p-to-s-polarization diffraction efficiency ratio at the Bragg angle corresponded with theoretical results to within 5%. Diffraction based wave propagation theory and a geometrical ray trace model were used to evaluate the imaging performance of these elements. Results from the diffraction based wave propagation model showed that the HOEs imaging performance had very minimal polarization dependence. The ray trace model indicated precise alignment and good wavelength stability are needed to achieve diffraction limited performance.
4
Cheng, Chin-Yuan. "Numerical electromagnetic modeling of a small aperture helical-fed reflector antenna." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176838193.
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Ament, Craig A. "High numerical aperture axial and transverse beam shaping using diffractive optics." Honors in the Major Thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1348.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Sciences
Physics
6
Messelink, W. A. C. M. "Numerical methods for the manufacture of optics using sub-aperture tools." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1471480/.
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Moore's law, predicting a doubling of transistor count per microprocessor every two years, remains valid, demonstrating exponential growth of computing power. This thesis examines the application of numerical methods to aid optical manufacturing for a number of case-studies related to the use of sub-aperture tools. One class of sub-aperture tools consists of rigid tools which are well suited to smooth surfaces. Their rigidity leads to mismatch between the surfaces of tool and aspheric workpieces. A novel, numerical method is introduced to analyse the mismatch qualitatively and quantitatively, with the advantage that it can readily be applied to aspheric or free-form surfaces for which an analytical approach is difficult or impossible. Furthermore, rigid tools exhibit an edge-effect due to the change in pressure between tool and workpiece when the tool hangs over the edge. An FEA model is introduced that simulates the tool and workpiece as separate entities, and models the contact between them; in contrast to the non-contact, single entity model reported in literature. This model is compared to experimental results. Another class of sub-aperture processes does not use physical tools to press abrasives onto the surface. A numerical analysis of one such process, Fluid Jet Polishing, is presented - work in collaboration with Chubu University. Numerical design of surfaces, required for generating tool-paths, is investigated, along with validation techniques for two test-cases, E-ELT mirror segments and IXO mirror segment slumping moulds. Conformal tools are not well suited to correct surface-errors with dimensions smaller than the contact area between tool and workpiece. A method with considerable potential is developed to analyse spatial-frequency error-content, and used to change the size of the contact area during a process run, as opposed to the constant-sized contact area that is state-of-the-art. These numerical methods reduce dependence on empirical data and operator experience, constituting important steps towards the ultimate and ambitious goal of fully-integrated process-automation.
7
Mokamati, Satyanarayana V. "Effect of aperture geometry on the steady flow through the narrow apertures in a pulp screen : numerical and experimental study." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31439.
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This investigation examines turbulent flow across a contoured wall with evenly-spaced slots and a series of flow bifurcations, as found in industrial pulp screening. The contoured wall and slotted apertures are formed from an array of 'wires', with cross-sectional geometry characterized by contour height and wire width. Four complementary studies were conducted to examine the velocity and turbulence characteristics of this complex flow. In the first study, a Computational Fluid Dynamics (CFD) model was developed to theoretically examine the effect of wire cross-sectional geometry on the flow field. The model shows that separation of the viscous layer occurs upstream of the aperture, and a vortex occupies the slot entry. As contour height increased, turbulence intensity near the wall increased. Further, turbulence intensity near the wall increased with decreasing wire width. It was shown that the ratio of contour height to wire width controls the boundary layer thickness and turbulence intensity near the wall. In the second study, the velocity field near the slot entry was experimentally measured using Particle Image Velocimetry (PIV) and was compared with theoretical predictions. In general, the vortex size and shape were similar to that predicted by CFD. In the third study, the velocity and turbulence intensity distributions above the wall were experimentally measured using Laser Doppler Velocimetry (LDV). The velocity near the wall was shown to decrease with contour height and increase with wire width. Further, the velocity near the wall was shown to increase as the flow through the slots increased. A correlation for velocity above the wall was determined as a function of the ratio of contour height to wire width, upstream velocity and flow through the slotted apertures. The correlation can be used to estimate shear stress at the wall. The maximum turbulence intensity near the wall was shown to increase with contour height and decrease with wire width. In the fourth study, the motion of 2 mm long nylon fibres moving near the apertures was experimentally observed using High-speed Video (HSV). Fibres were shown to interact with both the wires and the vortices during passage. It was observed that fibres only passed through the slots after impacting the wire and being pulled back into the slot by the vortex. Further, fibres were shown to pass through the slots with high contour wires more readily.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Chidley, Matthew D. "High Numerical Aperture Injection-Molded Miniature Objective For Fiber-Optic Confocal Reflectance Microscopy." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1300%5F1%5Fm.pdf&type=application/pdf.
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Romero, Carlos Alberto Macias. "High numerical aperture Muller matrix polarimetry and applications to multiplexed optical data storage." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517617.
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Jabbour, Toufic. "DESIGN, ANALYSIS, AND OPTIMIZATION OF DIFFRACTIVE OPTICAL ELEMENTS UNDER HIGH NUMERICAL APERTURE FOCUSING." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2837.
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The demand for high optical resolution has brought researchers to explore the use of beam shaping diffractive optical elements (DOEs) for improving performance of high numerical aperture (NA) optical systems. DOEs can be designed to modulate the amplitude, phase and/or polarization of a laser beam such that it focuses into a targeted irradiance distribution, or point spread function (PSF). The focused PSF can be reshaped in both the transverse focal plane and along the optical axis. Optical lithography, microscopy and direct laser writing are but a few of the many applications in which a properly designed DOE can significantly improve optical performance of the system. Designing DOEs for use in high-NA applications is complicated by electric field depolarization that occurs with tight focusing. The linear polarization of off-axis rays is tilted upon refraction towards the focal point, generating additional transverse and longitudinal polarization components. These additional field components contribute significantly to the shape of the PSF under tight focusing and cannot be neglected as in scalar diffraction theory. The PSF can be modeled more rigorously using the electromagnetic diffraction integrals derived by Wolf, which account for the full vector character of the field. In this work, optimization algorithms based on vector diffraction theory were developed for designing DOEs that reshape the PSF of a 1.4-NA objective lens. The optimization techniques include simple exhaustive search, iterative optimization (Method of Generalized Projections), and evolutionary computation (Particle Swarm Optimization). DOE designs were obtained that can reshape either the transverse PSF or the irradiance distribution along the optical axis. In one example of transverse beam shaping, all polarization components were simultaneously reshaped so their vector addition generates a focused flat-top square irradiance pattern. Other designs were obtained that can be used to narrow the axial irradiance distribution, giving a focused beam that is superresolved relative to the diffraction limit. In addition to theory, experimental studies were undertaken that include (1) fabricating an axially superresolving DOE, (2) incorporating the DOE into the optical setup, (3) imaging the focused PSF, and (4) measuring aberrations in the objective lens to study how these affect performance of the DOE.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Macias, Romero Carlos Alberto. "High numerical aperture Mueller matrix polarimetry and applications to multiplexed optical data storage." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5597.
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Optical data storage has reached a point where it is no longer possible to increase the storage capacity of an optical disk by conventional means. The work presented here, however, proves experimentally the validity of a novel solution to increase the capacity of an optical disk. Polarisation is used to store information multiplexed into shape-birefringent pits. A high numerical aperture scanning confocal microscope capable of measuring the Muller matrix of a sample is built to measure and characterise the polarisation properties of such pits. A number of results found during the development of the apparatus are given. Novel contributions are shown in the areas of imaging, the theory of coherence and polarisation, polarisation imaging, linear algebra, polarisation confocal microscopy, and optical data storage. It is shown that the storage capacity of any existent non-volumetric optical technology can be increased by 7.16 times, at least.
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Özdemir, Aytekin, Zeki Hayran, Yuzuru Takashima, and Hamza Kurt. "Polarization independent high transmission large numerical aperture laser beam focusing and deflection by dielectric Huygens’ metasurfaces." ELSEVIER SCIENCE BV, 2017. http://hdl.handle.net/10150/625955.
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In this letter, we propose all-dielectric Huygens' metasurface structures to construct high numerical aperture flat lenses and beam deflecting devices. The designed metasurface consists of two-dimensional array of all dielectric nanodisk resonators with spatially varying radii, thereby introducing judiciously designed phase shift to the propagating light. Owing to the overlap of Mie-type magnetic and electric resonances, high transmission was achieved with rigorous design analysis. The designed flat lenses have numerical aperture value of 0.85 and transmission values around 80%. It also offers easy fabrication and compatibility with available semiconductor technology. This spectrally and physically scalable, versatile design could implement efficient wavefront manipulation or beam shaping for high power laser beams, as well as various optical microscopy applications without requiring plasmonic structures that are susceptible to ohmic loss of metals and sensitive to the polarization of light.
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Jia, Baohua, and n/a. "A study on the complex evanescent focal region of a high numerical aperture objective and its applications." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20070205.150740.
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In recent years, optical near-field has received an ever-increasing attention owing to
its ability to localise optical signals beyond the diffraction limit. Optical near-field is
a non-propagating field existing in the close vicinity of a matter within a range less
than the wavelength of the illumination light and it carries the high spatial frequency
information showing the fine details of the matter.
An optical near-field can be generated by a near-field optical microscope with a
nano-aperture or a metal-coated fibre tip. However, common difficulties associated
with this approach, such as a fragile probe, a low throughput and signal-to-noise ratio,
and a slow response of gap controlling between the probe and the sample, make it
less applicable. Alternatively, optical near-field can be produced by total internal
reflection (TIR) occurring at the interface of a prism, which is capable of localising
the electromagnetic (EM) field in the close vicinity of the interface. However, in this
geometry, no confinement of the field can be achieved in the transverse direction,
whereas, in most applications such as optical trapping, micro-fabrication and optical
data storage, a transverse confinement of the light field is essential.
In order to achieve a transverse confinement of the light field, maintaining the
high spatial resolution of the optical near-field, and at the same time eliminating
the drawbacks associated with the conventional near-field optical microscope, a novel
near-field probe based on a high numerical aperture (NA) TIR objective combined
with annular illumination has been developed recently. In this arrangement, an
obstruction disk is inserted at the back aperture of the objective to block the light
with a convergence angle lower than the critical angle determined by the refractive
indices of the two media, resulting in a pure focused evanescent field in the second
medium.
The evanescent field produced by this method provides a useful tool for studying
light-matter interaction at the single molecule level not only because of its high
resolution but also due to its inherent merits such as no distance regulation, no heating
effect and simple experimental setup. But, the most significant advantage that makes
this method unique and superior to the other approaches in terms of producing the
optical near-field is that it allows the dynamic control of the focal field by simply
modulating the phase or amplitude or even the polarisation state of the incident beam
before it enters the objective so that complex illumination beams can be generated,
whereas in other fibre probe based approaches this goal is extremely difficult to achieve.
To make use of such a novel near-field probe, a thorough theoretical and
experimental investigation is required. A complete knowledge of the focused evanescent
field is a prerequisite for a wide range of applications including single molecule
detection, Raman spectroscopy, near-field non-linear imaging and near-field trapping.
Therefore, it is not only necessary but also urgent to exploit the focusing properties
of a focused evanescent field under complex field illumination both experimentally and
theoretically and this is the major aim of this thesis.
The complex fields, which are of particular interest in this thesis, are the radially
polarised beam and the Laguerre-Gaussian (LG) beam, because the former owns a
more compact circularly symmetric field distribution in the focal region when focused
by a high NA objective, while the latter is capable of rotating a trapped particle
by transferring the orbital angular momentum. Combining them with the focused
evanescent field is potentially able to induce novel functions in the near-field region,
which cannot be fulfilled by other near-field approaches. In this thesis, in order to
generate these two types of beams, a single liquid crystal spatial light modulator
(LCSLM) is employed to produce useful phase modulation to the incident beam.
Experimental characterisation of an evanescent focal spot is performed with
scanning near-field optical microscopy (SNOM), which is capable of providing the direct
mapping of the focused evanescent field not only because of its high spatial resolution
and its ability to detect the near-field and far-field signals simultaneously, but also due
to the motion of the piezzo-stage enables a three-dimensional characterisation of the
evanescent focal spot.
In this thesis, a SNOM system with an aluminum coated aperture probe is
implemented. The field distributions at both the interface and parallel planes with
a small distance away from the interface are obtained. To verify the applicability of
SNOM as a characterisation methodology, the field distribution in the focal region
of a high NA objective illuminated by a linearly polarised plane wave is measured
first. A focus splitting along the direction of incident polarisation is observed threedimensionally
near the interface under such a circumstance. It has been demonstrated
that the depolarisation effect plays an important role in determining the coupling
behaviour of the light into the fibre probe of SNOM. The good match between the
experimental results and theoretical predications confirms the validity of SNOM.
Theoretical investigation of a tightly focused radially polarised beam is undertaken
based on the vectorial-Debye diffraction theory because under the tight focusing of a
high NA objective, the vectorial nature of the highly localised field has to be carefully
considered in order to represent the field distribution accurately. The calculations
on the focusing properties of a radially polarised beam suggest that the longitudinal
field component in the focal region plays a dominant role in determining the overall
field distribution. Direct measurement of the focused evanescent radially polarised
beam in a three-dimensional manner near the interface is performed with SNOM. A
highly localised focal spot is achieved in the close vicinity of the coverglass. The
measured intensity distributions from SNOM show that correction of the focal spot
deformation associated with a linearly polarised beam is achieved by taking advantage
of the radially symmetric focal spot of a radially polarised beam. A smaller focal spot is
acquired due to the dominant longitudinal polarisation component in the focal region,
which possesses a more compact focal intensity distribution than that of the overall
field. The experimental results demonstrate a good agreement with the theoretical
expectations.
The fact that a radially polarised beam is capable of eliminating the focus
deformation often presented in the focal region of a high NA objective when a linearly
polarised beam is employed can be very useful in many applications, including microfabrication
using two-photon photopolymerisation technique. The theoretical study
on the two-photon point spread function (PSF) of a radially polarised beam indicates
that the focus elongation and splitting associated with a linearly polarised beam are
eliminated and the achievable lateral size of the focal spot is approximately a quarter
of the illumination wavelength, which is less than half of that under the illumination
of a linearly polarised beam. A further reductiont of the lateral size can be expected
by using annular radial beam illumination.
The investigation on the focusing properties of LG beams has also been one of
the major tasks of this thesis. Theoretical investigations of a focused evanescent LG
beam suggest that the phase shift induced by the boundary effect when a light beam
passes the interface satisfying TIR condition plays a vital role in determining the
overall shape of the total field distribution. A severe focal intensity deformation is
predicted theoretically in the case of focused evanescent LG beam illumination, which
might involve new physical phenomena when applied in the near-field trapping. Such
a focal intensity deformation is evidenced experimentally by the direct mapping result
obtained from the SNOM probe. A quantitative cross-section comparison with the
theoretical predication is conducted, which demonstrates a good agreement.
To achieve a controllable optical trap and rotation in the near-field region, complex
optical fields such as LG beams carrying orbital angular momentum, have been induced
for the manipulation of a polystyrene particle. The influence of the focal intensity
deformation on a near-field trapping has been thoroughly investigated. Rotation
motion of the particle is examined by mapping the two-dimensional (2D) transverse
trapping efficiency of the particle. Theoretical investigation reveals that a significant
tangential force component is generated on the particle when it is illuminated by a
focused evanescent LG beam. Such findings may prove useful in introducing a rotation
mechanism in near-field trapping.
The research investigations and methodologies described in this thesis provide a new
approach to characterise the near-field focal spot under complex field illumination.
It enhances the understanding of the novel near-field probe, thus opening the
pathway for numerous near-field applications including optical trapping, two-photon
excitation (photopolymerisation) and spectroscopy. The focal field rotation phenomena
demonstrated in this thesis may prove particularly beneficial in introducing a rotation
mechanism in near-field trapping using a focused evanescent field.
14
Jia, Baohua. "A study on the complex evanescent focal region of a high numerical aperture objective and its applications." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070205.150740/index.html.
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Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, Centre for Micro-Photonics, 2005.A thesis submitted for the degree of Doctor of Philosophy, Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2005. Typescript. Bibliography: p. 129-142.
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Jo, Sseunhyeun. "The vector behavior of aberrations in high numerical aperture (0.9 < NA < 3.1) laser focusing systems." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/290467.
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This dissertation investigates vector behavior of aberrations for high numerical aperture optical systems using a solid immersion lens (SIL). In order to analyze the system, this dissertation introduces the illumination system transfer function (ISTF), which is a map in the space of the exit pupil that shows reflection and transmission properties of individual plane waves that are emitted from corresponding points in the exit pupil. A vector analysis using ISTF presents the role of propagating and evanescent energy in the SIL systems, where the boundary between the them is defined by total internal reflection. The behavior of third-order aberrations such as coma and astigmatism, are dramatically affected by polarization in high NA systems. The irradiance distribution exhibits significantly different characteristics, depending on how coma or astigmatism is aligned with the incident linear polarized light. Vector effects including diffraction, polarization, and aberration, are used to analyze tolerances along with a comparison to geometrical optics. Apodization in amplitude and phase of the angular spectrum is generated in high NA focusing systems due to the difference in vector transmission and reflection for each plane wave. The size of the incident gaussian beam is effectively reduced at the exit pupil by the amplitude apodization and causes a spot size increase in image space. The apodization in phase is called gap-induced aberration due to its dependence on the air gap. The gap-induced aberration does not come from lens surface imperfection, and it exhibits multiple orders of spherical aberration and astigmatism. The apodization in amplitude and phase is well characterized by separable supergaussian functions, where each function depends on the refractive index of the SIL n SIL and the air gap height h. The best defocus, based on characteristics of gap-induced aberration, is suggested to be a good compensator only for low nSIL and h. The system performance, as represented by Strehl ratio and spot width, is characterized as a function of nSIL and h before and after defocus. C vector formalism is developed based on the common-mode and different-mode transmission coefficients between p and s polarization. Experiments to confirm the apodization are summarized and compared with simulation.
16
Abdel-Rahman, Mohamed A. "Numerical Reconstruction and Applications of Acoustic and Electromagnetic Ultra-Wideband Localized Pulses Generated by Dynamic Aperture Antennas." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/26335.
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A study is undertaken of the numerical reconstruction of acoustic and electromagnetic (EM) localized waves (LWs). The latter are carrier-free ultra-wideband pulses characterized by large focusing depths and extended ranges of localization. Special emphasis is placed on finite energy LWs that can be generated by dynamic aperture antennas with independently addressable elements. The reconstruction techniques are based on Huygens and Rayleigh-Sommerfeld integral I and II representations, both in the time and frequency domains. In contradistinction to the Weyl representation,they lend themselves to the physical realization of space-time aperture sources capable of generating localized wave solutions propagating away from the aperture plane. A detailed comparison of the three reconstruction techniques has been carried out in connection with LW solutions to the scalar wave equation, especially with respect to their handling of acausal components incorporated in the aperture excitation fields. In addition, a study is presented of the characteristic properties of LWs propagating through dispersive media modeled by the Klein-Gordon equation. It is demonstrated that contrary to expectation, the depletion of the spectral components of the LW Klein-Gordon field may be slower than that associated with the free space scalar field. Previous work by Power et al. [73] is extended by studying the acoustic bistatic scattering of a modified power spectrum (MPS) pulse from rigid and compressible spheres. The analysis allows the extraction of the radius of a sphere from the backscattered data. Finally, a special class of electromagnetic (EM) LWs, referred to as azimuthally polarized X waves (APXWs), is derived and their reconstruction is addressed, both in the time and frequency domains.Ph. D.
17
Li, Qinggele. "Optimization of point spread function of a high numerical aperture objective lens : application to high resolution optical imaging and fabrication." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0059/document.
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Ce travail de thèse porte sur la caractérisation et l'optimisation du spot de focalisation d'un objectif de microscope de grande ouverture numérique pour des applications d'imagerie super-résolue et de nanofabrication.Dans la première partie, nous avons systématiquement étudié les distributions de polarisation et d'intensité du faisceau laser dans la région du point focal en fonction de différents paramètres du faisceau incident tels que la phase, la polarisation, l’amplitude ainsi que l'influence du milieu de propagation, tel que l’indice de réfraction. Nous avons mis en oeuvre différentes méthodes théoriques pour contrôler et manipuler les distributions de polarisation et d'intensité du spot de focalisation. Ces prédictions théoriques sont vérifiées expérimentalement via un système optique confocal en mesurant l’image de fluorescence d’une nanoparticule d’or pour différentes caractéristiques.Dans la seconde partie de ce travail, une nouvelle microscopie basée sur le mécanisme d'absorption ultra-faible à un photon a été démontré théoriquement et expérimentalement. Le calcul théorique basé sur l'approche vectorielle de Debye, qui prend en compte l'effet d'absorption du matériau, montre qu'il est possible de focaliser le faisceau lumineux en profondeur à l'intérieur d'un matériau si celui-ci présente une absorption linéaire ultra-faible à la longueur d'onde d'excitation. Cette méthode, dite (LOPA), a ensuite permis de fabriquer des structures 2D et 3D submicrométriques, similaires à celles obtenues par la méthode utilisant l’absorption à deux photonsNowadays, far field optical microscopy is widely used in many fields, for fundamental research and applications. The low cost, simple operation, high flexibility are its main advantages. The key parameter of an optical microscope is the objective lens.This thesis's work focuses mainly on the characterization and optimization of the point spread function (PSF) of a high numerical aperture (NA) objective lens (OL) for applications of high resolution imaging and nano-fabrication.In the first part of the thesis, we have systematically investigated the dependency of polarization and intensity distributions of the focusing spot on numerous parameters, such as the phase, the polarization, and the beam mode of incident beam, as well as the refractive index mismatch. Then, we demonstrated theoretically different methods for manipulation of the polarization and intensity distributions of the focusing spot, which can have desired shapes and are useful for different applications. By using a home-made confocal microscope, we have experimentally verified some of the theoretical predictions, for example, vector properties of light beam under a tight focusing condition. In the second part of dissertation work, a new, simple and inexpensive method based on the one-photon absorption mechanism has been demonstrated theoretically and experimentally for 3D sub-micrometer imaging and fabrication applications. The theoretical calculation based on vectorial Debye approximation and taken into account the absorption effect of material shows that it is possible to focus the light tightly and deeply inside the material if the material presents a very low one-photon absorption (LOPA) at the excitation wavelength. We have then demonstrated experimentally that the LOPA microscopy allows to achieve 3D imaging and 3D fabrication with submicrometer resolution, similar to those obtained by two-photon absorption microscopy
18
Hill, Katherine I. "DNAPL migration in single fractures : issues of scale, aperture variability and matrix diffusion." University of Western Australia. School of Environmental Systems Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0003.
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[Truncated abstract] To date, many subsurface contaminant modelling studies have focused on increasing model complexity and measurement requirements to improve model accuracy and widen model application. However, due to the highly complex and heterogeneous nature of flow in the subsurface, the greater benefit in model development may lie in decreasing complexity by identifying key processes and parameters, simplifying the relationships that exist between them, and incorporating these relationships into simple models that recognise or quantify the inherent complexity and uncertainty. To address this need, this study aims to identify and isolate the key processes and parameters that control dense nonaqueous phase liquid (DNAPL) and aqueous phase migration through single, onedimensional fractures. This is a theoretical representation which allows the study of processes through conceptual and mathematical models. Fracture systems typically consist of multiple two-dimensional fractures in a three-dimensional network; however, these systems are computationally and conceptually demanding to investigate and were outside of the scope of this study. This work initially focuses on DNAPL migration in single, one-dimensional fractures. The similitude techniques of dimensional and inspectional analysis are performed to simplify the system and to develop breakthrough time scale factors. This approach relies heavily on the limitations of the equation used for the analysis and on the difficulty in representing variable aperture scenarios. The complexity of the conceptual model is then increased by embedding the fracture in a two-dimensional, porous matrix. ... These tools can be readily applied by the field investigator or computer modeller to make order-of-magnitude estimates of breakthrough times, reduce or target measurement requirements, and lessen the need to employ numerical multiphase flow models. To determine the implications of the results found in the one-dimensional studies to applications at the field scale, the complexity of the conceptual model was increased to a single, two-dimensional, planar fracture embedded in a three-dimensional porous matrix. The focus of this study was not DNAPL breakthrough times but the relative importance and interaction of different mass transport processes and parameters on plume migration and evolution. Observations clearly show that estimates of the size, location and concentration of the plume is highly dependent on the geologic media, the temporal and spatial location and resolution of measurements, and on the history, mass and location of the DNAPL source. In addition, the processes controlling mass transport (especially matrix diffusion and back diffusion) act in combination at the field scale in ways not always expected from an analysis of processes acting individually at smaller spatial and temporal scales. Serious concerns over the application of the common '1% Rule of Thumb' to predict DNAPL presence and the use of remediation efforts that rely largely on natural attenuation are raised. These findings have major implications for the field worker and computer modeller, and any characterisation, monitoring or remediation program development needs to be sensitive to these findings.
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Somers, Gary A. "Efficient numerical and asymptotic analyses of the dyadic aperture Green's function for a grounded material slab and its application to slot arrays /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487844105976161.
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Walsh, Jason L., and jason walsh@rmit edu au. "Development & evaluation of multiple optical trapping of colloidal particles using computer generated structured light fields." RMIT University. Applied Sciences, 2010. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20100209.143544.
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Colloidal particles are small particles ranging in size from nanometres to micrometres suspended in a fluid. Amongst many scientific and biological applications, they have been used to model crystallisation, vitrification, and particle interactions along with the use of colloidal model systems for the study of the fundamental nature of the fluid-crystal and fluid-glass phase transitions. It has been shown that colloidal particles can be trapped and manipulated using strongly-focused light beams known as optical tweezers, and this has paved the way for research into the area of micromanipulation using optical trapping. Holographic elements can replace multiple lenses in creating large numbers of optical tweezers and this is known as holographic optical trapping (HOT). A computer generated hologram can be designed to create large structured light fields, consisting of multiple foci, to enable trapping of multiple particles in arbitrary configurations. The overall aim of this project was to design, develop and test the suitability of a simple, inexpensive optical trapping arrangement suitable for multiple optical trapping. To achieve this, a theoretically-exact expression for the wavefront of a single point source was implemented in the coding scheme, allowing for the fast creation of multiple point sources suitable for holographic optical trapping experiments. Compensation for the spherical aberration present in the focusing optics was implemented into the coding scheme. Kodalith photographic film was chosen as the holographic recording medium for its high contrast and availability. The film has proven to be a successful medium, when used to record photographically-reduced images of high-quality printouts of the computed diffraction pattern, as it was able to successfully reproduce complex light fields. It is believed that this will be the first time that this film has been implemented for optical trapping purposes. The main limitations concerning the performance of the holograms recorded on Kodalith were the phase nonuniformities caused by unevenness in the film thickness which resulted in a failure to separately resolve light traps separated by less than about 5 (Mu)m. Index matching of the film between sheets of flat glass helped to compensate for these limitations. Holographic optical trapping was successfully observed using a variety of different initial beam powers, holographic aperture settings and light field configurations. Trapping experiments on of two types of particles (PMMA and polystyrene) were successfully conducted, with as little as ~ 150 (Mu)W per trap being required for multiple polystyrene trapping. However, particles were weakly trapped and were easily dislodged at these powers, and a higher power per trap of around 1 mW is preferred. The use of a relatively low numerical aperture (NA) 50 mm SLR lens for focusing the holographic optical traps was successful, proving that optical trapping can be conducted without the use of high NA microscope-objective lenses commonly used in other set ups. Holographic trapping of colloidal particles was successfully conducted at RMIT University for the first time proving the validity of the coding scheme, the recording method and the trapping arrangement.
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Mehrotra, Prateek. "High Aspect Ratio Lithographic Imaging at Ultra-high Numerical Apertures: Evanescent Interference Lithography with Resonant Reflector Underlayers." Thesis, University of Canterbury. Electrical and Computer Engineering, 2012. http://hdl.handle.net/10092/6935.
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A near-field technique known as evanescent interferometric lithography allows for high resolution imaging. However its primary limitation is that the image exponentially decays within the photoresist due to physical limits. This thesis aims to overcome this limitation and presents a method to considerably enhance the depth of focus of images created using evanescent interferometric lithography by using a material underlay beneath the photoresist.
A key enabler of this is the understanding that evanescent fields couple to surface states and operating within proximity of a resonance, the strength of the coupling allows for considerable energy extraction from the incident beam and redistribution of this energy in a photoresist cavity. This led to the analysis of the Fresnel equations, which suggested that such coupling was in fact the result of an enhanced reflectance that takes place at boundaries of carefully chosen materials. While it is known that metals and lossy dielectrics result in surface plasmon polaritons (SPP) and surface exciton polaritons (SEP) as conventional solutions to the Fresnel reflection equations for the TM polarization of light, there is no such naturally occurring surface state that allows evanescent wave enhancement with the TE polarization of light. Further investigation of the Fresnel reflection equations revealed both for TM and TE that in fact another solution exists that is but unconventional to enhance the reflectivity. This solution requires that one of the media have a negative loss. This is a new type of surface resonance that requires that one of the media be a gain medium; not one in the optical pumped sense but one that would naturally supply energy to a wave to make it grow. This new surface resonance is also a key result of this thesis. Clearly, however this is only a hypothetical solution as a real gain medium would violate the conservation of energy.
However, as it is only the reflectance of this gain medium that is useful for evanescent wave enhancement, in fact a multilayered stack consisting of naturally occurring materials is one way to achieve the desired reflectivity. This would of course be only an emulation of the reflectivity aspect of the gain medium. This multilayered stack is then an effective gain medium for the reflectivity purposes when imaging is carried out at a particular NA at a particular wavelength. This proposal is also a key idea of this thesis. At λ = 193 nm, this method was used to propose a feasible design to image high resolution structures, NA = 1.85 at an aspect ratio of ~3.2. To experimentally demonstrate the enhancements, a new type of solid immersion test bed, the solid immersion Lloyd's mirror interference lithography test-bed was constructed. High quality line and space patterns with a half-pitch of 55.5 nm were created using λ = 405 nm, corresponding to a NA of 1.824, that is well in the evanescent regime of light. Image depths of 33-40 nm were seen. Next, the evanescent image was coupled to an effective gain medium made up of a thin layer of hafnium oxide (HfO) upon silicon dioxide (SiO2). This resulted in a considerable depth enhancement, and 105 nm tall structures were imaged.
The work in this thesis details the construction of the solid immersion lithography test-bed, describes the implementation of the modeling tools, details the theory and analysis required to achieve the relevant solutions and understanding of the physical mechanism and finally experimentally demonstrates an enhancement that allows evanescent interferometric lithography beyond conventional limits.
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Kučera, Zdeněk. "Měření parametrů optických spojů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220660.
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Communication via fiber optical cable (links) is the latest advancement of the transmission media currently used for data transmission. Despite initial problems, using of this medium in recent years has greatly expanded due to their indisputable advantages. Optical cable is a great combination of reliability and security of data transfer. Its constantly improving transmission parameters contribute to the high speeds in the long-distance transmission of data. In the theoretical part of this work some kinds of optical cables are mentioned, also the most important parameters and the most widely used methods of measurement of these cables. Apart from that other methods of joining optical cables and the most used types of optical cables are also mentioned. The values of the decline and reflection, which are led into the device after connecting these parts into the optical lines. The device using the measuring method of the reverse reflection is also described in this thesis altogether with its most important parts and the way of the display of the measured track on the graphic image of the device. The problematics of identification and decline dead zone and the factors influencing the lenght of dead zone – the ability to identify two independent events on the link patchcord of the variable lenght, is also described in details in this thesis. In the practical part a series of measurements and evaluation (numerical and graphical) of the measured values of decline lenghts and identificating dead zones of the OTDR device will be carried out.
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Issa, Nader. "Modes and propagation in microstructured optical fibres." University of Sydney. Physics and Optical Fibre Technology Centre, 2005. http://hdl.handle.net/2123/613.
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Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions imposed outside the microstructure. This yields the leaky modes supported by the fibre. The boundary conditions are achieved exactly using a novel refinement scheme called the Adjustable Boundary Condition (ABC) method. Two implementations are programmed and their computational efficiencies are compared. Both use an azimuthal Fourier decomposition, but radially, a finite difference scheme is shown to be more efficient than a basis function expansion. The properties of the ABC method are then predicted theoretically using an original approach. It shows that the method is highly efficient, robust, automated and generally applicable to any implementation or to other radiating problems. A theoretical framework for the properties of modes in MOFs is also presented. It includes the use of the Bloch-Floquet theorem to provide a simpler and more efficient way to exploit microstructure symmetry. A new, but brief study of the modal birefringence properties in straight and spun fibres is also included. The theoretical and numerical tools are then applied to the study of polymer MOFs. Three types of fibres are numerically studied, fabricated and characterised. Each is of contemporary interest. Firstly, fabrication of the first MOFs with uniformly oriented elliptical holes is presented. A high degree of hole ellipticity is achieved using a simple technique relying on hole deformation during fibre draw. Both form and stress-optic birefringence are characterized over a broad scaled-wavelength range, which shows excellent agreement with numerical modelling. Secondly, an analysis of leaky modes in real air core MOFs, fabricated specifically for photonic band gap guidance, is then used to identify alternative guiding mechanisms. The supported leaky modes exhibit properties closely matching a simple hollow waveguide, weakly influenced by the surrounding microstructure. The analysis gives a quantitative determination of the wavelength dependent confinement loss of these modes and illustrates a mechanism not photonic band gap in origin by which colouration can be observed in such fibres. Finally, highly multimode MOFs (also called `air-clad' fibres) that have much wider light acceptance angles than conventional fibres are studied. An original and accurate method is presented for determining the numerical aperture of such fibres using leaky modes. The dependence on length, wavelength and various microstructure dimensions are evaluated for the first time for a class of fibres. These results show excellent agreement with published measurements on similar fibres and verify that bridge thicknesses much smaller than the wavelength are required for exceptionally high numerical apertures. The influence of multiple layers of holes on the numerical aperture and capture efficiency are then presented. It shows that a substantial increase in both these parameters can be achieved for some bridge thicknesses. Simple heuristic expressions for these quantities are given, which are based on the physical insight provided by the full numerical models. The work is then supported by the first fabrication attempts of large-core polymer MOFs with thin supporting bridges. These fibres exhibit relatively high numerical apertures and show good agreement with theoretical expectations over a very wide scaled-wavelength range.
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Pritschet, Andreas [Verfasser], and Josef [Akademischer Betreuer] Zweck. "Numerical and experimental investigations of Boersch Phase Plate equipped Condenser Apertures for use in Electron Magnetic Circular Dichroism experiments in a Transmission Electron Microscope / Andreas Pritschet. Betreuer: Josef Zweck." Regensburg : Universitätsbibliothek Regensburg, 2014. http://d-nb.info/1046721720/34.
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Marchiori, Victor. "Extraction photométrique bord des étoiles de la mission PLATO : masques photométriques optimaux pour la détection de planètes extra-solaires In-flight photometry extraction of PLATO targets Optimal apertures for detecting extrasolar planets The PLATO Solar-like Light-curve Simulator A tool to generate realistic stellar light-curves with instrumental effects representative of the PLATO mission." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEO014.
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PLAnetary Transits and Oscillations of stars (PLATO) est une mission scientifique spatiale européenne dédiée à la sismologie stellaire et à la recherche d’exoplanètes, et dont le développement est coordonné par l’Agence Spatiale Européenne. Avec un intérêt majeur sur des planètes du type terrestre située dans la zone habitable des étoiles du type solaire de la séquence principale, cette mission repose sur de la photométrie de très haute précision et exige une très grande stabilité des mesures. Elle s’appuie sur des techniques bien éprouvées : la méthode de transits pour la détection des planètes, suivie de mesures de vitesses radiales réalisées au sol, et l'analyse des oscillations stellaires pour la caractérisation des leurs étoiles hôtes. Grace à son très large champ de vue couvrant plus de deux mille dégrées carrés du ciel, l’instrument PLATO sera capable d’observer plusieurs centaines de milliers d’étoiles de magnitude apparente inférieure à treize dans le visible, et de détecter des milliers de systèmes planétaires. Par ailleurs, en raison des contraintes télémétriques du satellite, l’extraction photométrique de la majorité des étoiles devra être effectuée à bord en s’appuyant sur des méthodes optimisées. Pour autant, la méthode d’extraction photométriques par masques a été adoptée pour sa faisabilité compte-tenu des contraintes à bord. Dans ce contexte, la problématique de développement des masques photométriques optimaux représente le cœur du travail de recherche présenté dans cette thèse. Dans les missions précédentes de la même catégorie de PLATO, à savoir CoRoT, Kepler et TESS, des masques photométriques ont été conçus selon une approche reposant uniquement sur la minimisation du rapport bruit sur signal, car la sensibilité à laquelle un transit planétaire peut être identifié, dans une courbe de lumière, est fortement corrélée à son niveau de bruit. En revanche, plus il est facile d'identifier une planète, en raison d'un niveau de bruit suffisamment faible, plus élevée est la probabilité que des objets en arrière-plan entrant dans la scène (par exemple des systèmes binaires reproduisant des vrais transits planétaires) soient détectés. Étant donné que la plupart des étoiles-cible de PLATO n’auront pas des images au sol pour l’identification des faux positifs, une conception de masques photométriques reposant uniquement sur la sensibilité de détection des vrais transits planétaires, sans faire suffisamment attention aux potentiels faux positifs, n’est donc pas forcément la meilleure stratégie. Pour vérifier cette hypothèse, deux métriques scientifiques ont été introduites nous permettant de quantifier directement la sensibilité d'un masque à la détection des vrais, d’une part, et de faux transits planétaires, d’autre part. Ainsi, le masque optimal a été défini comme étant celui qui donne le meilleur compromis entre ces deux métriques. Cette approche, originale à cette thèse, s’est avérée décisive pour la détermination d’un modèle de masque statistiquement capable de détecter des planètes de façon quasi-optimale, tout en étant substantiellement moins sensible aux faux positifs. Globalement, ces travaux constituent une étape importante dans la conception des chaînes de traitement des données bord et sol de la mission PLATO, ainsi que pour ses algorithmes de détection et de caractérisation des transits planétairesPLAnetary Transits and Oscillations of stars (PLATO) is a European spatial scientific mission dedicated to asteroseismology and searching for exoplanets, and whose development is being carried out by the European Space Agency. With focus on Earth-like planets orbiting the habitable zone of main-sequence Sun-like stars, the mission relies on very high precision photometry and requires great stability of measurements. The mission is founded upon well-proven techniques: the transit method for detecting exoplanets, along with radial velocity follow-up from the ground, and the analysis of stellar oscillations for characterizing their host stars. Thanks to its very large field of view encompassing more than two thousand square degrees of the sky, the PLATO instrument will be able to observe several hundreds of thousands of stars with apparent magnitude lower than thirteen in the visible band, and thousands of planetary systems. In contrast, because of satellite telemetry constraints, photometry will have to be extracted in flight for most of the PLATO targets. For that, mask-based (aperture) photometry was adopted because of its sufficiently high performance and relatively low complexity for implementing on board. In this context, the development of optimal photometric apertures represents the core of the research work presented in this thesis. In the previous missions of the same category of PLATO (i.e. CoRoT, Kepler and TESS), photometric apertures were designed following an approach based uniquely on the minimization of the noise-to-signal ratio, because the sensitivity at which a planet transit can be found in a light curve is strongly correlated to its noise level. On the other hand, the higher the ease in identifying a transit-like signal because of a sufficiently low noise level, the higher the probability that background objects in the scene (e.g. binary systems reproducing legitimate planet transits) are detected. Since most of the PLATO targets will not have images available on ground for the identification of false positives, conceiving photometric masks based solely on how well a transit-like signal can be detected, paying no attention to potential false positives may not be the best strategy. To verify the consistence of this hypothesis, two science metrics were introduced allowing one to directly quantify the sensitivity of an aperture in detecting true and false planet transits. Then, the optimal aperture was defined as that which gives the best compromise between these two metrics. Such an approach, novel to this thesis, has been proven to be decisive for the determination of a mask model capable to provide near maximum planet yield and substantially reduced occurrence of false positives. Overall, this work constitutes an important step in the design of both on-board and on-ground science data processing pipelines of the PLATO mission
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Patier, Laurent. "Etude de techniques de calculs multi-domaines appliqués à la compatibilité électromagnétique." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00834164.
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Le contexte d'étude est celui de la Compatibilité ÉlectroMagnétique (CEM). L'objectif de la CEM est, comme son nom l'indique, d'assurer la compatibilité entre une source de perturbation électromagnétique et un système électronique victime. Or, la prédiction de ces niveaux de perturbation ne peut pas s'effectuer à l'aide d'un simple calcul analytique, en raison de la géométrie qui est généralement complexe pour le système que l'on étudie, tel que le champ à l'intérieur d'un cockpit d'avion par exemple. En conséquence, nous sommes contraints d'employer des méthodes numériques, dans le but de prédire ce niveau de couplage entre les sources et les victimes. Parmi les nombreuses méthodes numériques existantes à ce jour, les méthodes Multi-Domaines (MD) sont très prisées. En effet, elles offrent la liberté aux utilisateurs de choisir la méthode numérique la plus adaptée, en fonction de la zone géométrique à calculer. Au sein de ces méthodes MD, la " Domain Decomposition Method " (DDM) présente l'avantage supplémentaire de découpler chacun de ces domaines. En conséquence, la DDM est particulièrement intéressante, vis-à-vis des méthodes concurrentes, en particulier sur l'aspect du coût numérique. Pour preuve, l'ONERA continue de développer cette méthode qui ne cesse de montrer son efficacité depuis plusieurs années, notamment pour le domaine des Surfaces Équivalentes Radar (SER) et des antennes. L'objectif de l'étude est de tirer profit des avantages de cette méthode pour des problématiques de CEM. Jusqu'à maintenant, de nombreuses applications de CEM, traitées par le code DDM, fournissaient des résultats fortement bruités. Même pour des problématiques électromagnétiques très simples, des problèmes subsistaient, sans explication convaincante. Ceci justifie cette étude. Le but de cette thèse est de pouvoir appliquer ce formalisme DDM à des problématiques de CEM. Dans cette optique, nous avons été amenés à redéfinir un certain nombre de conventions, qui interviennent au sein de la DDM. Par ailleurs, nous avons développé un modèle spécifique pour les ouvertures, qui sont des voies de couplage privilégiées par les ondes, à l'intérieur des cavités que représentent les blindages. Comme les ouvertures sont, en pratique, de petites dimensions devant la longueur d'onde, on s'est intéressé à un modèle quasi-statique. Nous proposons alors un modèle, qui a été implémenté, puis validé. Suite à ce modèle, nous avons développé une méthode originale, basée sur un calcul en deux étapes, permettant de ne plus discrétiser le support des ouvertures dans les calculs 3D.
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YANG, KAI-MING, and 楊凱茗. "Simulation and Design of Numerical Aperture Expander." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/2c5b8p.
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Fang, Chun-Chieh, and 方俊傑. "Experiement and simulation on the continuous numerical aperture proposition of sub-wavelength annular aperture." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/52292697390053020848.
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碩士國立臺灣大學
應用力學研究所
96
The three-dimensional electromagnetic field dispersion of focused beam is an important issue for optical applications. Since 1959, Richard and Wolf had generated radially polarized (RP) beam by optical mechanism. After that, radial vector beam has attracted a great deal of discussions in recent years. Using sub-wavelength annular aperture (SAA) structure is a brand new method to generate non-diffraction doughnut beam. When the RP beam is focused by SAA structure, the focused RP beam in free space was found to propagate in the J1 Bessel beam format, Both simulation and experimental results showed that sub-wavelength focal spot and long depth of focus were achieved in the above-mentioned combinations. The electric field at focal plane of RP beam can be separated into longitudinal and transverse components. Due to their features and different intensity distribution, there are special phenomena in the electrical field at focus. For example, the intensity ratio of longitudinal and transversal component are found to be related to the numerical aperture (NA) of focal lens used and the focal pattern also depends on NA. For the long depth of focus of SAA structure by RP beam incidence, we proposed that SAA structure is a continuous numerical aperture (NA) optical element. To verify this proposition, we compared the properties of SAA structure with the traditional objective lens illuminated by RP beam.
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Chu, Kuan-Ju, and 朱冠儒. "Image Modeling for a High Numerical Aperture Microlithography System." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/74606125552720114882.
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碩士臺灣大學
電機工程學研究所
95
In the field of microlithography the demand for highly integrated electronic circuits has motivated investigation into better lens resolution. Traditional models used in microlithography are based on scalar image formation under the Fresnel approximations. This approximation holds in the low system but it breaks down when the exit pupil diameter is of the same order as the distance from pupil to image (high ), i.e. . We successfully find vector imaging model in a high numerical aperture microlithography system. We survey papers about image modeling, and clearly reorganize the useful formulates from these papers. And we design different kinds of photo masks to compare the aerial image of the scalar imaging model and of the vector imaging model. We can clearly find that the intensity of the scalar model is much different from the intensity of the vector model when (high NA). So we should adopt the vector model when we need to calculate the aerial image in a high microlithography projection system. In this thesis, we introduce some basic knowledge of optical lithography in chapter 1 and foundations of scalar diffraction theory in chapter 2. Then, scalar imaging with coherent illumination and partially coherent illumination is introduced in chapter3. The formulation about vector imaging model in a high numerical aperture microlithography system is derived in chapter 4. Simulation result and some comparisons will be shown in chapter 5. Finally conclusion will be made in chapter 6.
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Lee, Ming-Hung, and 李明洪. "Design, fabrication and testing ofhigh-numerical-aperture GaN microlens." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/89601886566185509760.
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碩士國立中央大學
物理研究所
90
Abstract Plano-convex diffractive microlenses were fabricated in GaN-based materials with a gray-level mask for the first time. The surface relief of the gray-level diffractive microlens on photoresist was transferred onto GaN by inductively coupled plasma etching technique. The microlenses were characterized with a blue laser diode emitting at 405nm. The focal length of the GaN diffractive microlens is 14.5cm. The potential of the realization of the high-numerical-aperture diffractive microlens in GaN with gray-level mask is discussed.
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Chu, Kuan-Ju. "Image Modeling for a High Numerical Aperture Microlithography System." 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2907200707560300.
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Jhang, Jia-Cih, and 張家慈. "Numerical Calculation of Coaxially Dual Aperture Liquid Crystal Lens." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/48805558006017803756.
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碩士國立彰化師範大學
光電科技研究所
104
In this thesis, we proposed a simulation model which successfully demonstrates the experimental results of coaxially dual aperture liquid crystal (LC) lens. Coaxially dual aperture LC lens has been known to improve the depth of field and to realize the switchable field of view of the optical system. In order to understand the physical mechanism, we proposed a charge density model and introduced a correction factor to simulate the coaxially dual aperture LC lens. The proposed model and obtained results were similar to experimental results. On the other hand, the experimental technique that inhibiting the disclination lines of the coaxially dual aperture LC lens by separately application of voltages on the top and middle aperture electrodes was also predicted by the simulation. The correction factor was found linearly dependent on the applied voltage.
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Tang, Shih-Huan, and 湯士桓. "High Numerical Aperture Microlens Fabrication by Using the Microlens Mask." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/06545912565505406772.
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碩士國立中興大學
精密工程學系所
105
This research presents a novel method for the high numerical aperture microlens fabrication using the microlens mask to improve optical imaging and fabrication technology. The research is divided into three parts. First, the light intensity distribution can be simulated by optical simulation software-TracePro and obtained the numerical analysis for finding an optimal parameter value. Second part is the microlens mask fabrication. The photoresist (AZ-4620) column array was fabricated by lithography and followed by the thermal reflow to form the microlens array on the glass substrate as the mask. Microlens with a high Numerical Aperture (NA) can be obtained by lithography using the microlens mask. Last, using optical microscope, surface topography meter (alpha step) and Scanning Electron Microscope (SEM) to analysis lens geometric measurement and then verify the simulation results. Moreover, the theoretical formula is used to calculate the microlens N.A. value. This study was successful for fabricating the novel microlenses which diameter was 30.06μm and 40.15μm. After geometrical measurement and formula calculation, the NAs of microlens were 0.618 and 0.581, respectively.
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He, Gung-Jing, and 何恭境. "Numerical analysis of surface plasmon effects on metal nanocavity and aperture." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/44054882438185199694.
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碩士健行科技大學
電子工程系碩士班
103
This thesis is divided into two topics: In topic 1, we numerically investigate the surface plasmon resonance (SPR) modes in periodic silver-shell nanopearl and its dimer arrays with the core relative permittivities filled inside the dielectric holes (DHs) using finite element method (FEM) with three-dimensional calculations. Numerical results of resonant wavelengths corresponding to the effects of different period of unit cells, radii of DHs, illumination wavelengths and the DH core relative permittivity of silver-shell nanopearls are reported as well. Simulation results show that silver-shell nanopearl arrays and its dimer arrays with DHs exhibit tunable SPR modes corresponding to the bonding and anti-bonding modes, respectively, that are not observed for the solid silver cases with the same volume. The boundary symmetry on the inner and outer surfaces of the silver nanopearl arrays with DHs can be broken by their structural and material parameters. It is shown that only the bonding mode can be excited at the lower core relative permittivity, whereas both the bonding and anti-bonding modes can be excited at the higher core relative permittivity. In topic 2, we numerically investigate the optical properties of near field effects on an array of metallic nanohole by using finite element method. The peak resonant wavelengths can be tuned by varying the geometry of metallic nanohole size and material parameters of medium filled inside the metallic nanohole. The detail behavior of physical mechanism of surface plasmon effect in metallic nanohole are also discussed in this topic. Simulation results show that the metallic nanohole arrays with DHs exhibit red shifted phenomenon that are not observed for the air hole case. These results are crucial in designing localized SPR sensors and other optical devices based on periodic metal nanoparticle array structures. keywords: finite element method, surface plasmon resonance (SPR), bonding and anti-bonding modes.
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CHUANG, CHING MIN, and 莊清閔. "Improved Lithography Resolution by Varying I-LINE Optical Lithography Numerical Aperture." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/41063964861734146495.
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碩士長庚大學
電子工程學系
100
DRAM (Dynamic Random-Access Memory) is required for larger and larger capacity memory chips with the progress of technology. The IC (Integrated Circuit) manufacturers certainly want to make a largest memory capacity with small wafer size. All they have to do is reducing cost by decreasing the feature size for reaching the requirement of advanced DRAM in next generation. In this study, a process step of via hole was researched. The maximum resolution of window target is 335 nm (CD PATTEM) by KrF (248 nm). However, I-Line wavelength is 365 nm, still can not reach the best focus. Therefore, an I-Line exposure with changing parameters of aperture was used for improving the resolution, and it has reached the same efficiency similar to KrF. In our research, by changing the aperture of conventional and annular and adding a mask with the aperture size of 0.62, the minimum value is 0.2833 μm which was measured by SEM. This result proves that we can have a higher resolution by improved I-Line exposure. Although there still need to improve, technology factories would have the best resolution with lowest cost in the future.
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Chen, Yen-Ching, and 陳延慶. "Numerical stuides on build-up of self-staring KLM lasers without aperture." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/27337254491547676520.
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碩士國立交通大學
光電(科學)研究所
83
In this thesis, we have established a numerical model of kerr lens mode-locking(KLM) Ti:sapphire laser cavity by ABCD matrix. In this model, we can simultaneously consider the spatial and temporal effects including self-focusing, gain guiding, free space propagation, group velocity dispersion (GVD), bandwidth limiting, near resonance phase shift, nonlinear absorption and self-phase modulation (SPM). At first, We obtained a solution of a stable cavity, then modified the term of gain saturation to simulate the pulse grown of this laser by assumming CW mode and KLM mode coexisting. We found that there is a turing point in the time evolution of output pulsewidth, where GVD optimally compensates SPM to achieve the limitation of pulse compression. In consequence of self-focusing, the gain of KLM mode becomes larger than that of CW mode, and the pulse is further compressed by the rise of pulse energy. Finally, the KLM mode drains out all of the energy stored in the gain medium and quenchs CW mode, a steady-state solution of mode-locked pulse train is obtained.
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Chen, Hsin-Jung, and 陳信榮. "Numerical Analysis and Application of Electromagnetic Shielding of Aperture Effect of Metal Shield." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/93733555272837260574.
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Bairos, Kenley. "Insights from use of a 3-D Discrete-Fracture Network Numerical Model for Hydraulic Test Analysis." Thesis, 2012. http://hdl.handle.net/10214/3673.
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Transmissivity (T) and Hydraulic apertures are often calculated from hydraulic test data obtained in fractured rock using analytical solutions such as the Thiem and cubic law equations developed for flow through unconsolidated porous media. These analytical solutions use a variety of simplifying assumptions, which are often violated due to the complex nature of flow through fractured rock systems which introduces error into the calculated hydraulic apertures. A 3-D discrete fracture network numerical model (SMOKER) for flow in dual-permeability media was used to simulate constant-head straddle packer tests to assess the errors in fracture characterization that result from deviations from the Thiem and cubic law assumptions caused by permeable rock matrix, variable aperture fractures, and complex flow patterns. The simulations indicate that SMOKER offers potential as a useful tool for representing non-ideal scenarios of rock and fracture network characteristics to assist in estimates and error analysis in T values and resultant errors in hydraulic aperture.NSERC: Natural Sciences and Engineering Research Council of Canada
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Petchsingto, Tawatchai Karpyn Zuleima Tharays. "Numerical study of fracture aperture characteristics and their impact on single-phase flow and capillary-dominated displacement." 2008. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2520/index.html.
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Lee, Jooyoung. "Development of an automated system for the measurement of focal ratio degradation of high numerical aperture fibres." Thesis, 2019. http://hdl.handle.net/1828/11024.
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The thesis presents the development and testing of an automated fibre optic test system for the measurement of focal ratio degradation (FRD) in high numerical aperture fibres. In particular, the fibres under examination are being proposed for use in the Maunakea Spectroscopic Explorer (MSE), a new telescope currently being designed for wide-field surveys of the night sky. A critical subsystem of the MSE is the Fiber Transmission System (FiTS) that connects the focal plane to the telescope’s spectrographs. In preparation for MSE-FiTS, a method of characterizing the focal ratio degradation (FRD), between the input and output of every fibre, of candidate multi-mode fibres is highly important. The ultimate goal is the testing of all 4,332 fibres after assembly and prior to installation on MSE. An optical bench has been constructed to test the performance of an automated characterization system; a variation on the collimated beam test. Herein we present the underlying analysis FRD measurement method, the optical design of the test bench, the motion control system and the software for measuring FRD, and controlling the automated test system. The open-source automation software is also introduced; the Big FiTS Fibre Wrapper (Big FFW). The results of tests performed using the Big FFW on samples of candidate fibres are presented and compared with the results in the literature using manual methods. The results suggest that the candidate MSE fibre meets the science requirement of less than 5% focal ratio degradation for an f/2 input beam measured at the fibre output. There is less than 1% disagreement between the automated measurement method and manual methods reported in the literature. The fully automated system can measure the FRD of up to 10 fibres in a typical MSE fibre bundle configuration.Graduate
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Alex-Change and 張凱榮. "A Study on the Effects of Substrate on the Numerical Aperture of Microlens Fabricated by Reflow Process." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/02886860285699736739.
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碩士國立中興大學
機械工程學系
93
This paper first derived the relationship between NA and the height/diameter ratio (h/D) as a dimensionless geometric parameter of lens via thick-lens theory. Geometric characteristics for lens with high NA are analyzed and simulated. Effects of different substrates on the NA of microlens, fabricated by reflow process using photoresist, are also investigated. Geometry of microlens is analyzed based on the contact angle, measured from the photoresist on different substrates with experiments. Micrlens arrays with diamters of 30μm and 40μm are successfully fabricated with photolithography. Experimental results showed that microlenses on tefelon can reach semi-spehere with NA close to 0.42. This is consistant with the geometric model analyzed bycontact angels. Further experimental investigation on the effects of surface roughness of substrate on the lens geometry are then designed and conducted. Substrates with high contact angle, including glass, silicon wafer and tefelon block, are grounded to different surface condition before the photoresist coated. Microlens arrays are fabricated via reflow process. The results showed that substrate with high surface roughness results in high NA of microlens. This also consists with the model predicted by the surface energy. The main contributions of this research include: (i) verifying the relationship between the h/D ratio and the NA for thick lens, and (ii) experimental verification on the geometry of microlens based on the surface energy and contact angle between the substrate and photoresist.
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Liu, Sung-Lin, and 劉松林. "Numerical and Experimental Study on applying Synthetic Aperture Focusing Technique to Test Cracks and Defects in Reinforced Concrete." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/17512009468205965826.
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碩士中華大學
土木工程學系碩士班
102
In this paper the capability of the Synthetic Aperture Focusing Technique (SAFT) in detecting and imaging the cracks in plain concrete and the voids in reinforced concrete were studied. This research first utilized the Finite Element models to simulate the response of the stress wave propagation of a plain concrete with horizontal and tilted cracks and of a reinforced concrete with void subjected to impacting forces. The response signals were analyzed with SAFT and the resultant images were presented so that the feasibility of applying this technique on scanning and revealing the cracks and voids embedded in reinforced concrete can be studied. Two experimental specimens are then constructed in this research to be impacted by steel balls of different sizes and analysis was conducted with SAFT imaging procedure. Finally the results from experiments and from numerical simulation were compared for the purpose of verification. It was revealed from numerical simulation and experimental verification that the resolution of the images would be affected by the wave length of the stress waves introduced by the impacts of different steel balls. If the wave length of the introduced stress waves is short, fine cracks in the specimen can be revealed, whereas if the wave length is long, the interfering of reinforced bars can be reduced so that the defective voids can be scanned and revealed. Finally the feasibility of rotating the surfaces for impacting tests for testing and revealing defects was studied.
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"Recent Techniques for Regularization in Partial Differential Equations and Imaging." Doctoral diss., 2018. http://hdl.handle.net/2286/R.I.49073.
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abstract: Inverse problems model real world phenomena from data, where the data are often noisy and models contain errors. This leads to instabilities, multiple solution vectors and thus ill-posedness. To solve ill-posed inverse problems, regularization is typically used as a penalty function to induce stability and allow for the incorporation of a priori information about the desired solution. In this thesis, high order regularization techniques are developed for image and function reconstruction from noisy or misleading data. Specifically the incorporation of the Polynomial Annihilation operator allows for the accurate exploitation of the sparse representation of each function in the edge domain.
This dissertation tackles three main problems through the development of novel reconstruction techniques: (i) reconstructing one and two dimensional functions from multiple measurement vectors using variance based joint sparsity when a subset of the measurements contain false and/or misleading information, (ii) approximating discontinuous solutions to hyperbolic partial differential equations by enhancing typical solvers with l1 regularization, and (iii) reducing model assumptions in synthetic aperture radar image formation, specifically for the purpose of speckle reduction and phase error correction. While the common thread tying these problems together is the use of high order regularization, the defining characteristics of each of these problems create unique challenges.
Fast and robust numerical algorithms are also developed so that these problems can be solved efficiently without requiring fine tuning of parameters. Indeed, the numerical experiments presented in this dissertation strongly suggest that the new methodology provides more accurate and robust solutions to a variety of ill-posed inverse problems.Dissertation/Thesis
Doctoral Dissertation Mathematics 2018
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Chiu, Chin-Lung, and 邱進隆. "Numerical Modeling and Experimental Verification on the Aggregate and Boundary Effects Induced in Defect Scanning with Stress Wave and Synthetic Aperture Focusing Methods." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/15540161206593270804.
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碩士中華大學
土木與工程資訊學系碩士班
95
The application of a nondestructive testing technology to evaluate the defects embedded in concrete structures is proposed in this paper. Based on using transient elastic waves in conjunction of the Synthetic Aperture Focusing method, the defects implied in concrete may be presented with the scanning images. In this study, the propagation of elastic waves was first simulated with the numerical method of Finite Element. The collected response data was then processed with the Synthetic Aperture Focusing method so that the geometric information of the embedded defects may be presented with gray-scaled images. The numerical models were also changed in this study to investigate the factors that affect the resolution of tests. Finally, concrete specimen with a void was cast for the experiment of scanning the defect. The experimental results not only presented the high potential of this method in practical application, but also verified the correctness of the numerical models so that this finite element model may be used as the tool to carry out vast kinds of parametric studies. Besides, the effect of the re-bars on the scanning results will also be roughly studied in this research.
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Lee, Byungtark. "Numerical Investigation of Fractured Reservoir Response to Injection/Extraction Using a Fully Coupled Displacement Discontinuity Method." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10100.
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In geothermal reservoirs and unconventional gas reservoirs with very low matrix permeability, fractures are the main routes of fluid flow and heat transport, so the fracture permeability change is important. In fact, reservoir development under this circumstance relies on generation and stimulation of a fracture network. This thesis presents numerical simulation of the response of a fractured rock to injection and extraction considering the role of poro-thermoelasticity and joint deformation. Fluid flow and heat transport in the fracture are treated using a finite difference method while the fracture and rock matrix deformation are determined using the displacement discontinuity method (DDM).
The fractures response to fluid injection and extraction is affected both by the induced stresses as well as by the initial far-field stress. The latter is accounted for using the non-equilibrium condition, i.e., relaxing the assumption that the rock joints are in equilibrium with the in-situ stress state.
The fully coupled DDM simulation has been used to carry out several case studies to model the fracture response under different injection/extractions, in-situ stresses, joint geometries and properties, for both equilibrium and non-equilibrium conditions. The following observations are made: i) Fluid injection increases the pressure causing the joint to open. For non-isothermal injection, cooling increases the fracture aperture drastically by inducing tensile stresses. Higher fracture aperture means higher conductivity. ii) In a single fracture under constant anisotropic in-situ stress (non-equilibrium condition), permanent shear slip is encountered on all fracture segments when the shear strength is overcome by shear stress in response to fluid injection. With cooling operation, the fracture segments in the vicinity of the injection point are opened due to cooling-induced tensile stress and injection pressure, and all the fracture segments experience slip. iii) Fluid pressure in fractures increases in response to compression. The fluid compressibility and joint stiffness play a role. iv) When there are injection and extraction in fractured reservoirs, the cooler fluid flows through the fracture channels from the injection point to extraction well extracting heat from the warmer reservoir matrix. As the matrix cools, the resulting thermal stress increases the fracture apertures and thus increases the fracture conductivity. v) Injection decreases the amount of effective stress due to pressure increase in fracture and matrix near a well. In contrast, extraction increases the amount of effective stress due to pressure drop in fracture and matrix.