Dissertations / Theses on the topic 'Optical metrology'
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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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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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Logan, Randy. "Optical metrology of thin films." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/46094.
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Huang, Zixin. "Protocols for optical quantum metrology." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18067.
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This thesis explores various protocols which can be applied to quantum metrology, such that precision of the measurement can beat the best classical approaches. We first demonstrate that ancilla-assisted schemes can improve phase estimation in the presence of noise, and we propose an experiment to demonstrate these effects. Given that the use of ancillae helps, it is no surprise that there are noisy channels for which the optimal strategy may depend on the noise level. We show that there is a non-trivial crossover between the ancilla-assisted strategy and the parallel-entangled strategy for Pauli noise channels and the amplitude damping channel. We see that under certain circumstances, the environment cannot access the parameter of interest. We then integrated techniques from quantum communication, to derive a general framework that renders quantum metrology protocols into cryptographic ones. Here the protocol is unconditionally secure if the trusted parties wish only to achieve the standard quantum limit. If Heisenberg-limited precision is to be achieved, they sacrifice some security, where adversaries can access information, but only at the risk of getting caught at it (cheat-sensitivity). In many scenarios, the quantum Fisher information is achieved for only one value of the phase. In a particular phase estimation scheme that measures the parity at the output of a Mach-Zehnder interferometer where the input is a two-mode squeezed vacuum, this problem is particularly imminent. We apply an adaptive technique to resolve this issue, showing that one can achieve precisions substantially below the shot noise limit. The key to a quadratically enhanced improvement in quantum metrology is entanglement. Finally, we demonstrate in a photonic system how high-dimensional entanglement can be certified, and provide an alternate interpretation of entanglement from an information-theoretic perspective.
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Ji, Zheng. "The Use of Optical Metrology in Active Positioning of a Lens." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699892/.
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Precisely positioned optical lenses are currently required for many highly repetitive mechanics and applications. Thus the need for micron-scale repetition between opto-mechanical units is evident, especially in industrial manufacturing and medical breakthroughs. In this thesis, a novel optical metrology system is proposed, designed, and built whose purpose is to precisely locate the center of a mechanical fixture and then to assemble a plano-convex optical lens into the located position of the fixture. Center location specifications up to ±3 µm decenter and ±0.001° tilting accuracy are required. Nine precisely positioned lenses and fixtures were built with eight units passing the requirements with a repetitive standard deviation of ±0.15 µm or less. The assembled units show satisfactory results.
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Idowu, Ade. "Dynamic metrology of error motions in precision spindles using optical metrology." Thesis, Cranfield University, 1998. http://dspace.lib.cranfield.ac.uk/handle/1826/3688.
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Knowledge of the accuracies of air bearing spindles in the sub-micrometre to nanometre range is required for the design, commissioning and operation of ultra-precise machine tools, measurement systems and other machines employing high precision rotational motion. In order to verify the dynamic performance of a spindle, measurement is required of its error motions in the unwanted five degrees of freedom (one axial, two tilts and two radial motions). Presentation of these error motions (eg in the form of polar charts) can then be used to provide critical spindle metrology data including total, asynchronous and average error motion rosette profiles and their average and peak values. This thesis describes a metrology system based on optical interferometry for measuring such unwanted error motions in three degrees of freedom involving motion along the spindle axis (axial rectilinear displacement and tilts about orthogonal axes), incurred with rotation of a precision air spindle over its specified speed-range. The system is not sensitive to orthoaxial translations which may be measured using alternative methods. Possible alternative techniques for measuring any of the degrees of freedom include an array of proximity sensors, (one for each translational degree of freedom and a further one for each of the other rotational degrees of freedom), to measure the run-out of an artefact. Proximity sensors based upon capacitive or optical fibre back-scatter techniques each offer the required single degree-of-freedom non-contacting capability and bandwidth. In the current work, a Fizeau interferometer is used to monitor the motion of the spindle of a vertical axis ultra-precision facing machine using a test-artefact. This is a mirror with less than one fringe departure from planarity from which interferogram. fringe-patterns are captured, digitised and analysed synchronously as the spindle rotates. The issue of the prediction of the dynamic form and motions of the observed interferograrn arises and the earlier theory is extended to optimise the set-up, including provision of automatic servo- alignment of the optical axis with the axis of the spindle. Measurement interferograrn data is sampled at selected angular incremental positions of spindle-rotation and image processing techniques used to filter the fringe pattern, enabling measurement of spindle tilt and axial displacement. Issues of sampling with respect to the anticipated spatial angular frequency of the spindle run-out are considered with respect to the speed/frequency capability of data-acquisition and processing arrangements. Essentially, with a spindle rotating at typical machining speeds of 300- 3000 rev/min, for consistent error motions, the resolution of an error plot is principally a function of observational time. It is foreseen that the system will be applicable in research and production-support in ultra-precision machining production processes and in rotational metrology.
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Seong, Kibyung. "Optical Metrology for Transmission Interferometric Testing." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194698.
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The degree of sophistication and customization available in optical components has been driven by advances in lens design and fabrication. The optical testing of these components remains a challenge. In particular, the precision measurement of the properties of transmissive optics such as transmitted wavefront, surface figure, and index of refraction continues to require new methodology tools.A method of surface figure measurement is described based on the transmitted wavefront of an optical element obtained from a Mach-Zehnder interferometer. Given known values for the refractive index and center thickness, along with the sample's transmitted wavefront, the unknown surface profile is reconstructed in a deterministic way. The technique relies on knowledge of one of the surfaces of the element, such as an easy to measure plano or spherical surface, and is well-suited for testing aspheric surfaces. Additionally, this method has the advantage of making measurements on multiplexed surfaces, such as a lenslet array.Since the index of refraction of materials varies with wavelength, the test sample undergoes chromatic effects with wavelength. Chromatic aberration is an important concern whenever optics are designed for use in the visible spectrum. A method has been presented for obtaining the longitudinal chromatic aberration of a test part from the transmitted wavefronts at 5 different wavelengths. The longitudinal chromatic aberration measurements on a plano-convex lens and an achromat are presented.Injection molding is becoming a popular manufacturing method for optical plastic elements because of low cost and mass production. During injection molding, the plastic lenses undergo large pressure and temperature changes so that the resulting lens has a spatially-varying index. Since the index is assumed to be a single number in the design stage, except for index-gradient lenses, an inhomogeneous index of the sample can cause a decrease in optical performance. The surface reconstruction algorithm can be modified to find two dimensional index values over the test aperture. In this case, both surfaces are measured by an external interferometer and one unknown parameter is the index value.
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Tsatourian, Veronika. "Femtosecond combs for optical frequency metrology." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2747.
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This thesis is dedicated to femtosecond combs as a tool for optical frequency metrology and as an integral part of an optical clock. After an overview of optical frequency measurement techniques, the design of two frequency combs based on mode-locked femtosecond lasers as they were at the beginning of my project is described. The first comb is based on an Er:fibre laser operating at a central wavelength of 1550 nm with a repetition rate of 100 MHz. The second is a Ti:sapphire-laser-based comb operating at a central wavelength of 810 nm with a repetition rate of 87 MHz. Improvements to the original design of the Ti:sapphire comb are detailed in the next chapter. A novel f-to-2f self-referencing scheme based on a pair of Wollaston prisms and employing a PPKTP crystal for SHG results in up to 20 dB enhancement of the signal to noise ratio in the carrier-envelope offset frequency beat signal f0 and in up to 15 dB lower phase noise in the f0 beat signal compared to a Michelson interferometer based system. Next, the factors influencing the stability and accuracy of the microwave reference signal and the performance of two synthesisers used for the stabilisation of the frequency combs were investigated. It is shown that stability of the maser reference signal is reduced by the distribution system by factor of 1.5. A fractional frequency change of 4.1(0.7) × 10−16 (K/h)−1 was measured for the better of the two synthesisers (an IFR 2023A) indicating that for accurate frequency measurements the synthesiser signal should be monitored to enable systematic frequency corrections to be made. Finally, an absolute frequency measurement of the electric quadrupole clock transition in a frequency standard based on a single 171Yb+ trapped ion is described. The result f = 688 358 979 309 310 ± 9 Hz agrees with an independent measurement made by the PTB group within the uncertainty of the measurements.
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Huang, Run. "High Precision Optical Surface Metrology using Deflectometry." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/581252.
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Software Configurable Optical Test System (SCOTS) developed at University of Arizona is a highly efficient optical metrology technique based on the principle of deflectometry, which can achieve comparable accuracy with interferometry but with low-cost hardware. In a SCOTS test, an LCD display is used to generate structured light pattern to illuminate the test optics and the reflected light is captured by a digital camera. The surface slope of test optics is determined by triangulation of the display pixels, test optics, and the camera. The surface shape is obtained by the integration of the slopes. Comparing to interferometry, which has long served as an accurate non-contact optical metrology technology, SCOTS overcomes the limitation of dynamic range and sensitivity to environment. It is able to achieve high dynamic range slope measurement without requiring null optics. In this dissertation, the sensitivity and performance of the test system have been analyzed comprehensively. Sophisticated calibrations of system components have been investigated and implemented in different metrology projects to push this technology to a higher accuracy including low-order terms. A compact on-axis SCOTS system lowered the testing geometry sensitivity in the metrology of 1-meter highly aspheric secondary mirror of Large Binocular Telescope. Sub-nm accuracy was achieved in testing a high precision elliptical X-ray mirror by using reference calibration. A well-calibrated SCOTS was successfully constructed and is, at the time of writing this dissertation, being used to provide surface metrology feedback for the fabrication of the primary mirror of Daniel K. Inouye Solar Telescope which is a 4-meter off-axis parabola with more than 8 mm aspherical departure.
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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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Matos, Lia Machado de. "Octave-spanning lasers for optical metrology applications." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34389.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, February 2006.Includes bibliographical references (p. 136-144).
This thesis describes the first octave-spanning frequency comb based on a prismless, Ti:sapphire laser. It covers in detail the design and construction of the laser system, as well as the electronic stabilization scheme used to control the frequencies of the mode comb. The system developed is suitable for optical metrology applications in general, although the version here presented is locked to the hydrogen 1S-2S transition frequency in ultracold hydrogen. A detailed study of the carrier-envelope phase dynamics and noise characteristics of octave-spanning Ti:sapphire lasers is presented. We model the effect of the laser dynamics on the residual carrier-envelope phase noise by deriving a transfer function representation of the octave-spanning frequency comb. The modelled phase noise and the experimental results show excellent agreement. The model developed greatly enhances our capability of predicting the residual carrier-envelope phase noise in octave-spanning lasers, an important aspect in many time and frequency domain applications. Potential applications of the current system to ultraprecise optical frequency metrology of ultracold hydrogen are described.
by Lia Machado de Matos.
Ph.D.
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King, Christopher William. "A new approach to stitching optical metrology data." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444244/.
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The next generation of optical instruments, including telescopes and imaging apparatus, will generate an increased requirement for larger and more complex optical forms. A major limiting factor for the production of such optical components is the metrology: how do we measure such parts and with respect to what reference datum This metrology can be thought of as part of a complete cycle in the production of optical components and it is currently the most challenging aspect of production. This thesis investigates a new and complete approach to stitching optical metrology data to extend the effective aperture or, in future, the dynamic range of optical metrology instruments. A practical approach is used to build up a complete process for stitching on piano and spherical parts. The work forms a basis upon which a stitching system for aspheres might be developed in the future, which is inherently more complicated. Beginning with a historical perspective and a review of optical polishing and metrology, the work presented relates the commercially available metrology instruments to the stitching process developed. The stitching is then performed by a numerical optimization routine that seeks to join together overlapping sub-aperture measurements by consideration of the aberrations introduced by the measurement scenario, and by the overlap areas between measurements. The stitching is part of a larger project, the PPARC Optical Manipulation and Metrology project, and was to benefit from new wavefront sensing technology developed by a project partner, and to be used for the sub-aperture measurement. Difficult mathematical problems meant that such a wavefront sensor was not avail able for this work and a work-around was therefore developed using commercial instruments. The techniques developed can be adapted to work on commercial ma chine platforms, and in partuicular, the OMAM NPL/UCL swing-arm profilometer described in chapter 5, or the computer controlled polishing machines as manufactured by the project's industrial sponsors,- Zeeko ltd. The novel process involving physical surface fiducialization is then developed for a standpoint of instrument particularities followed by the development of a numerical optimization to derive the best stitching. The software, developed in Matlab, is then tested on simulated and real data and shows much promise. The stitching accuracy is found to be dictated by the quality of the acquired data and the precision with which fiducials in a given measurement can be related to each other. Finally a summary is given for a future direction of this work and how it might be improved upon.
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Kirkland, Eric Alan. "A nano coordinate machine for optical dimensional metrology." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/16525.
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Evans, Christopher James. "Absolute figure metrology of high precision optical surfaces." Thesis, University of Birmingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.552738.
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Phase measuring interferometers can provide extremely repeatable comparisons between reference and test surfaces. This thesis explores the limits to which the accuracy of measurement of flat, spherical and aspheric optical surfaces can be made to approach that repeatability. Analysis of conventional methods for separating errors in flats (the three flat test) shows that the systematic differences between repeated measurements can be predicted from the shape of the surfaces and a plausible estimate of relocation errors. Errors introduced by distortion are analysed. New methods for separation of errors associated with the reference surface and test part are introduced, together with a new method for visualising the errors. When aspheres are measured with respect to a spherical reference, non-common path errors may be substantial. A software correction method, based on the use of Zernike polynomials, is introduced for errors associated with the imaging system of the interferometer. Further errors arise from non-common path use of multi-element transmission spheres. The errors can be estimated using ray trace code, and corrections made. The uncertainties are, however, higher than required for future optical systems. Thus the concept for a next generation interferometer, not subject to the limitations identified in this work, is introduced
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Liu, Chao. "Optical modeling and resist metrology for deep-UV photolithography." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4233.
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This thesis first presents a novel and highly accurate methodology for investigating
the kinetics of photoacid diffusion and catalyzed-deprotection of positive-tone
chemically amplified resists during post exposure bake (PEB) by in-situ monitoring the
change of resist and capacitance (RC) of resist film during PEB. Deprotection converts
the protecting group to volatile group, which changes the dielectric constant of resist. So
the deprotection rate can be extracted from the change of capacitance. The photoacid
diffusivity is extracted from the resistance change because diffusivity determines the rate
of change of the acid distribution. Furthermore, by comparing the R and C curves, the
dependence of acid diffusivity on reaction state can be extracted. The kinetics of
non-Fickean acid transportation, deprotection, free volume generation and
absorption/escaping, and resist shrinkage is analyzed and a comprehensive model is
proposed that includes these chemical/physical mechanisms.
Then in this thesis a novel lithographic technique, liquid immersion contact
lithography (LICL) is proposed and the simulations are performed to illustrate its main features and advantages. Significant depth-of-field (DOF) enhancement can be achieved
for large pitch gratings with deep-UV light (û=248nm) illumination with both TM and
TE polarizations by liquid immersion. Better than 100nm DOF can be achieved by when
printing 70nm apertures. The simulation results show that it is very promising to apply
this technique in scanning near field optical microscopy.
Finally, a rigorous, full vector imaging model of non-ideal mask is developed and
the simulation of the imaging of such a mask with 2D roughness is performed. Line edge
roughness (LER) has been a major issue limiting the performance of sub-100nm
photolithography. A lot of factors contribute to LER, including mask roughness, lens
imperfection, resist chemistry, process variation, etc. To evaluate the effect of mask
roughness on LER, a rigorous full vector model has been developed by the author. We
calculate the electromagnetic (EM) field immediately after a rough mask by using
TEMPEST and simulate the projected wafer image with SPLAT. The EM field and wafer
image deviate from those from an ideal mask. LER is finally calculated based on the
projected image.
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Jones, Jonathan. "Quantum metrology with a single ytterbium ion optical clock." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8741/.
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The thesis focusses on the developments and measurements of the Yb+ optical clock at NPL. During my period there, new ion traps, trap control electronics and optical cavities have been developed. Numerous measurement campaigns have been conducted, where we measured the absolute frequency of both optical clock transitions in Yb+ relative to caesium, for the first time ever directly measured the frequency ratio of these transitions, and performed numerous international comparisons against other optical clocks. The total systematic uncertainty of the clock is now expected to be at the mid-low 10-18 level, with published uncertainty budgets at the mid 10-17 level, making it a strong candidate for a future redefinition of the second. The exotic electron structure of the excited levels in Yb+ make it a promising system for tests of fundamental physics. The frequencies of the transitions used in the Yb+ clock are highly sensitive to changes in the fine structure constant, α, which is predicted to vary by many physical theories beyond the standard model. By combing our absolute frequency measurements with a history of atomic clock measurements, we can place new best limits on the present day time variation of α, and the proton-electron mass ratio, µ.
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Al, Mahdawi Basil Mohamed Nouri. "Senior monitoring by using sensors network and optical metrology." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD085.
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L’objectif du travail de cette thèse est la contribution au développement de nouvelles techniques dans le domaine dessystèmes de détection sans marqueur pour une utilisation dans trois domaines vitaux de la santé en utilisant des capteursinnovants et peu coûteux. Pour la réalisation de nos objectifs nous avons eu recours principalement à de l’électroniqueembarquées et du traitement du signal en utilisant le capteur Kinect. Des résultats encourageants ont été obtenus et sontprésentés tout au long de cette thèse. Dans la première partie de ce travail, nous présentons un nouveau système desurveillance visuelle sans marqueur en temps réel pour détecter et suivre les personnes âgées et surveiller leurs activitésdans leur environnement intérieur en utilisant un réseau de capteurs Kinect. Le système identifie également l’événementde chute des personnes âgées sous surveillance. Dans la deuxième partie nous utilisons également le capteur Kinectmais cette fois ci pour la détection sans marqueur des mouvements de la tête d’un patient lors d’un examen utilisant LaTomographie par Emission de Positons (CT/PET) du cerveau. Ce travail est basé sur la compensation de la dégradationde l’image TEP due aux mouvements de la tête du patient. Pour nos essais un cobaye dit « fantôme » a été réalisé,les résultats sur le fantôme sont prometteur ce qui a donné lieu à un test sur un vrai patient volontaire. Les résultatsfinaux montrent l’efficacité de ce nouveau système. La troisième partie du travail présente la mise en oeuvre d’un nouveausystème intelligent pour contrôler un fauteuil roulant électrique par des mouvements spéciaux de la tête toujours sansmarqueur. Un algorithme adapté est conçu pour détecter en continu les degrés des mouvements du visage en utilisant lecapteur Kinect. Fautes de fauteuil roulant électrique, le système a été testé sur un véhicule radio commandéThe objective of the work of this thesis is the contribution in developing novel technical methods in the field of marker-lesssensing systems for use in three vital health areas by using new inexpensive sensors. Several scientific areas are involvedin achieving our objective such as; electronics and signal processing by using the Kinect sensor. Encouraging results wereachieved as presented throughout this thesis. In the first part of this work we present a new real-time marker-less visualsurveillance system for detecting and tracking seniors and monitoring their activities in the indoor environment by usingnetwork of Kinect sensors. The system also identifies the fall event with the elderly. In the second part, we present anew approach for a marker-less movement detection system for influential head movements in the brain Positron EmissionTomography imaging (CT/PET) by employing the Kinect sensor. This work addresses the compensation of the PET imagedegradation due to subject’s head movements. A developed particular phantom and volunteer studies were carried out.The experimental results show the effectiveness of this new system. The third part of the work presents the design andimplementation of a new smart system for controlling an electric wheelchair by special mark-less head movements. Anadaptable algorithm is designed to continuously detect the rotation degrees of the face pose using the Kinect sensor inreal-time that are interpreted as controlling signals through a hardware interface for the electric wheelchair actuators
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Balskus, Karolis. "Versatile femtosecond optical parametric oscillator frequency combs for metrology." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3198.
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This thesis addresses the development of broadly tunable, high repetition rate frequency combs in the mid-IR region. A novel PPKTP crystal design was used to provide phasematching for parametric oscillation and simultaneously give efficient pump+idler sum-frequency generation (SFG). This innovation enabled a fully stabilized idler comb from a 333-MHz femtosecond optical parametric oscillator to be generated in which the carrier envelope offset frequency fCEO together with the repetition frequency fREP were stabilised. This OPO platform was then extended to demonstrate, via harmonic pumping, a fully stabilized 1-GHz OPO frequency comb from a 333-MHz pump laser. Next, an alternative route to a 1-GHz OPO comb was investigated by synchronously pumping an OPO directly with a 1-GHz Ti:sapphire laser. Here the comb was fully stabilized for the signal, idler and pump pulses by using a narrow linewidth CW diode laser developed for the project and whose design is also presented. A further increase in the comb mode spacing was performed with a Fabry-Pérot cavity. A stabilised cavity was used to filter 1.5 m signal pulses from a 333-MHz repetition rate OPO frequency comb to yield a 10-GHz comb. The length of the Fabry-Pérot cavity was dither locked to a single-frequency ECDL and later on directly to the OPO frequency comb. Finally the 333-MHz OPO comb was demonstrated in an optical frequency metrology experiment. The frequency comb mode number and the absolute frequency of a narrow-linewidth CW laser were measured and the performance of the OPO comb was found to be comparable to that of a commercial fibre laser comb used as a benchmark in the experiment.
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Kovalchuk, Evgeny. "Optical parametric oscillators for precision IR spectroscopy and metrology." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15759.
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In der vorliegenden Doktorarbeit wird ein Dauerstrich Optisch Parametrischer Oszillator (cw OPO) vorgestellt, der speziell für die hochauflösende Dopplerfreie Molekülspektroskopie und Metrologie entwickelt wurde. Der kontrollierte Zugang zu jeder beliebigen Wellenlänge im breiten Emissionsspektrum von OPOs wie auch das präzise Abstimmen seiner Ausgangsfrequenz über zu untersuchende molekulare und atomare Übergänge stellten lange Zeit Probleme dar, deren Lösung die Grundzielsetzung dieser Arbeit war. Das im Laufe dieser Arbeit entwickelte System hat diese Ziele vollständig erreicht, was durch verschiedene Messungen und Anwendungen demonstriert wurde. Zu diesem Zweck wurde ein neues OPO-Design mit einem Intracavity-Etalon entwickelt und aufgebaut, wobei der OPO auf dem Konzept eines einfach-resonanten cw OPOs mit resonanter Pumpwelle basiert. Die OPO-Ausgangsstrahlung zeigt sehr gute Langzeitstabilität und Spektraleigenschaften, welche durch direkte Frequenzvergleichsmessungen mit einem optischen Methan-Frequenzstandard im Infraroten bestimmt wurden. Eine Idler-Linienbreite von 12 kHz und ein Modensprung-freier Betrieb des OPOs über einen Zeitraum von einigen Tagen wurde beobachtet. Außerdem wurde gezeigt, dass ein OPO zu einer hochstabilen optischen Referenz phasengelockt und somit seine Frequenz sehr genau kontrolliert und durchgestimmt werden kann. Als erste erfolgreiche Anwendung eines OPOs in der Dopplerfreien Spektroskopie wurde ein Aufbau zur Frequenz-Modulationsspektroskopie in Methan realisiert. Weiterhin, wurde der entwickelte cw OPO mit einem femtosekunden optischen Frequenzkamm kombiniert, um eine neue Idee für eine kohärente Verbindung zwischen dem sichtbaren und dem infraroten Spektralbereich zu realisieren. Als erste Demonstration dieser Technologie wurde ein direkter absoluter Frequenzvergleich zwischen einem Jod-stabilisierten Laser bei 532 nm und einem Methan-stabilisierten Laser bei 3390 nm durchgeführt.This thesis presents a continuous-wave optical parametric oscillator (cw OPO), specially developed for high-resolution Doppler-free molecular spectroscopy and metrology. The basic objective was to solve the long-standing problem of controlled access to any desired wavelength in the wide emission range of OPOs, including the ability to precisely tune the output frequency over the molecular and atomic transitions of interest. The system implemented during this work fully achieves these goals and its performance was demonstrated in various measurements and applications. For this aim, a new design for the OPO cavity with an intracavity etalon was implemented, extending the concept of a cw singly resonant OPO with resonated pump wave. The newly developed device demonstrates very good long-term stability and spectral properties, which were determined in direct beat frequency measurements with a methane infrared optical frequency standard. Thus, an idler radiation linewidth of 12 kHz and mode-hop-free operation of the OPO over several days were observed. Furthermore, it was shown that an OPO can be phase locked to a highly stable optical reference and thus much more precisely controlled and tuned. As the first successful application of OPOs in Doppler-free spectroscopy, a frequency modulation spectroscopy setup for detection of sub-Doppler resonances in methane was implemented. Furthermore, the developed cw OPO was integrated with a femtosecond optical frequency comb to realize a new concept for a coherent link between the visible and infrared spectral ranges. As a first demonstration of this technique, a direct absolute frequency comparison between an iodine stabilized laser at 532 nm and a methane stabilized laser at 3390 nm was performed.
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Maldonado, Alejandro V. "High Resolution Optical Surface Metrology with the Slope Measuring Portable Optical Test System." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/337294.
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New optical designs strive to achieve extreme performance, and continually increase the complexity of prescribed optical shapes, which often require wide dynamic range and high resolution. SCOTS, or the Software Configurable Optical Test System, can measure a wide range of optical surfaces with high sensitivity using surface slope. This dissertation introduces a high resolution version of SCOTS called SPOTS, or the Slope measuring Portable Optical Test System. SPOTS improves the metrology of surface features on the order of sub-millimeter to decimeter spatial scales and nanometer to micrometer level height scales. Currently there is no optical surface metrology instrument with the same utility. SCOTS uses a computer controlled display (such as an LCD monitor) and camera to measure surface slopes over the entire surface of a mirror. SPOTS differs in that an additional lens is placed near the surface under test. A small prototype system is discussed in general, providing the support for the design of future SPOTS devices. Then the SCOTS instrument transfer function is addressed, which defines the way the system filters surface heights. Lastly, the calibration and performance of larger SPOTS device is analyzed with example measurements of the 8.4-m diameter aspheric Large Synoptic Survey Telescope's (LSST) primary mirror. In general optical systems have a transfer function, which filters data. In the case of optical imaging systems the instrument transfer function (ITF) follows the modulation transfer function (MTF), which causes a reduction of contrast as a function of increasing spatial frequency due to diffraction. In SCOTS, ITF is shown to decrease the measured height of surface features as their spatial frequency increases, and thus the SCOTS and SPOTS ITF is proportional to their camera system's MTF. Theory and simulations are supported by a SCOTS measurement of a test piece with a set of lithographically written sinusoidal surface topographies. In addition, an example of a simple inverse filtering technique is provided. The success of a small SPOTS proof of concept instrument paved the way for a new larger prototype system, which is intended to measure subaperture regions on large optical mirrors. On large optics, the prototype SPOTS is light weight and it rests on the surface being tested. One advantage of this SPOTS is stability over time in maintaining its calibration. Thus the optician can simply place SPOTS on the mirror, perform a simple alignment, collect measurement data, then pick the system up and repeat at a new location. The entire process takes approximately 5 to 10 minutes, of which 3 minutes is spent collecting data. SPOTS' simplicity of design, light weight, robustness, wide dynamic range, and high sensitivity make it a useful tool for optical shop use during the fabrication and testing process of large and small optics.
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Wang, Xinchi. "Separate adjustment of close range photogrammetric measurements." Thesis, City University London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264245.
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Mitchell, John Benjamin. "A new algorithm for the absolute metrology of optical surfaces." Thesis, Kingston University, 1996. http://eprints.kingston.ac.uk/20596/.
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In this thesis, the problem of the metrology of optical surfaces is examined. The need for accurate metrology is established with regard to optical wavefronts reflecting or refracting at the surfaces of optical components. Optical interferometry is identified as the most useful analytical tool for surface metrology by virtue of its high precision and accuracy. Accordingly the theory of interferometry is briefly presented. The application of the theory to the interferometric instruments is shown together with measuring configurations for the various optical surfaces commonly encountered. An extensive overview of the techniques used to evaluate data from interferometric measurements is given with particular emphasis on precision phase measuring methods. Most interferometric measurements of surfaces aremade relative to a reference surface of high quality. Where the accuracy of the surface to be measured is comparable to, or better than, that of the reference surface, an absolute measurement technique is required in order to give meaningful results. A review is given of the existing methods for the absolute measurement of nominally flat and spherical surfaces and the shortcomings of these methods. A new algorithm for the absolute testing of flat surfaces is developed, based on relative measurements of pairs from a population of three test flats in a number of positional combinations. The new method has a number of potential advantages over those previously described, particularly since it yields information about the flats over their entire surfaces on a square grid of points. The implementation of the new method on a Zygo Mark IV interferometer is described together with experimental results using both synthesized and actualexperimental data. Suggestions for improvements to the method and its implementation are made. A speculative study of other possible techniques for absolute flatness measurement is presented, including the possible application of the Ritchey-Common test, point diffraction interferometry, phase conjugation and profilometry. A full and up to date survey of the pertinent literature is given throughout the thesis.
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Heideman, Kyle C. "Surface Metrology of Contact Lenses in Saline Solution." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/337379.
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Measurement of the quality and performance of soft contact lenses is not new and is continually evolving as manufacturing methods develop and more complicated contact lenses become available. Qualification of soft contact lenses has not been a simple task since they are fundamentally difficult to measure. The shape of the lens is extremely sensitive to how the lens is supported and the material properties can change quickly with time. These lenses have been measured in several different ways, the most successful being non-contact optical methods that measure the lens while it is immersed in saline solution. All of these tests measure the lens in transmission and do not directly measure the surface structure of the lens. The reason for this is that the Fresnel reflectivity of the surface of a contact lens in saline solution is about 0.07%. Surface measurements have been performed in air, but not in saline. The lens needs to be measured in solution so that it can maintain its true shape. An interferometer is proposed, constructed, verified, and demonstrated to measure the aspheric low reflectivity surfaces of a contact lens while they are immersed in saline solution. The problem is extremely difficult and requires delicate balance between stray light mitigation, color correction, and polarization management. The resulting system implements reverse raytracing algorithms to correct for retrace errors so that highly aspheric, toric, and distorted contact lens surfaces can be measured. The interferometer is capable of measuring both surfaces from the same side of the contact lens as well as the lens thickness. These measurements along with the index of refraction of the lens material are enough build a complete 3D model of the lens. A simulated transmission test of the 3D model has been shown to match the real transmission test of the same lens to within 32nm RMS or 1/20th of a wave at the test wavelength.
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Faichnie, David Malcolm. "Thin Film Optical Metrology Using Principles of Wavefront Sensing and Interference." Thesis, Heriot-Watt University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486271.
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The work contained within this thesis considers the applicability of wavefront sensing to the problem of laminate and thin film metrology and considers whether such technology can be applied to the problem of in-situ thickness measurement. Some initial investigations were carried out to develop new applications based on current technology. The main body of the work investigated the development of a thickness monitor based on measuring the separation of surface reflections and the further development required to incorporate a wavefront sensor into the system to allow the reflected wavefronts to be analysed. The initial system was developed theoretically using a mathematical model and tested experimentally giving a high dynamic range (lOJlm - 8mm) and good accuracy (50nm) for this application. Analysis of higher order aberration modes introduced by the film structure have been carried out in simulation and a robust algorithm fonnulated to measure film thickness and surface tilt simultaneously using a single measurement. The most prominent aberrations introduced by laminate layers were identified as tilt, defocus, astigmatism and coma and monitoring of these modes allowed thickness variation to be measured. Experiments and simulations were shown to agree and further development of a sensor based on analysis of the interference between wavefronts allowed much thinner laminates to be measured. This work will allow further development of an industrial thickness monitor capable of measuring film thickness and surface fonn in multiple laminates simultaneously and suitable for in-line in-situ real time measurements.
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Marian, Adela Ye Jun. "Direct frequency comb spectroscopy for optical frequency metrology and coherent interactions." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/dissertations/fullcit/3186934.
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Choi, Sukwon. "Stress metrology and thermometry of AlGaN/GaN HEMTs using optical methods." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49108.
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The development of state-of-the-art AlGaN/GaN high electron mobility transistors (HEMTs) has shown much promise for advancing future RF and microwave communication systems. These revolutionary devices demonstrate great potential and superior performance and many commercial companies have demonstrated excellent reliability results based on multiple temperature accelerated stress testing. However, a physical understanding of the various reliability limiting mechanisms is lacking and the role and relative contribution of the various intrinsic material factors, such as physical stress and strain has not been clearly explained in the literature. Part of issues that impact device reliability are the mechanical stresses induced in the devices as well as the self-heating that also limit device performance. Thus, quantification of stress and temperature in AlGaN/GaN HEMTs is of great importance.
To address some of the needs for metrology to quantify stress in AlGaN/GaN HEMTs, micro-Raman spectroscopy and micro-photoluminescence (micro-PL) were utilized to quantify the residual stress in these devices. Through the use of micro-Raman and micro-PL optical characterization methods, mapping of the vertical and lateral stress distributions in the device channels was performed. Results show that stress can be influenced by the substrate material as well as patterned structures including metal electrodes and passivation layers.
Previously developed and reported micro-Raman thermometry methods require an extensive calibration process for each device investigated. To improve the implementation of micro-Raman thermometry, a method was developed which offers both experimental simplicity and high accuracy in temperature results utilizing a universal calibration method that can be applied to a broad range of GaN based devices. This eliminates the need for performing calibration on different devices. By utilizing this technique, it was revealed that under identical power dissipation levels, the bias conditions (combination of Vgs and Vds) alter the heat generation profile across the conductive channel and thus influence the degree of device peak temperature.
The role of stress in the degradation of AlGaN/GaN HEMTs was also explored. A combined analysis using micro-Raman spectroscopy, coupled electro-thermo-mechanical simulation, and electrical step stress tests was conducted to investigate the link between performance degradation and the evolution of total stress in devices. It was found that in addition to stresses arising from the inverse piezoelectric effect, the substrate induced residual stress and the operational themo-elastic stress in the AlGaN layer play a major role in determining the onset of mechanically driven device degradation. Overall, these experiments were the first to suggest that a critical level of stress may exist at which point device degradation will start to occur.
The optical characterization methods developed in this study show the ability to reveal unprecedented relationships between temperature/stress and device performance/reliability. They can be used as effective tools for facilitating improvement of the reliability of future AlGaN/GaN HEMTs.
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Grotti, Jacopo [Verfasser]. "A transportable optical lattice clock for metrology and geodesy / Jacopo Grotti." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2018. http://d-nb.info/1172414173/34.
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McDonald, G. J. "Optical sampling and metrology using a soliton-effect compression pulse source." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19219/.
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A low jitter optical pulse source for applications including optical sampling and optical metrology was modelled and then experimentally implemented using photonic components. Dispersion and non-linear fibre effects were utilised to compress a periodic optical waveform to generate pulses of the order of 10 picoseconds duration, via soliton-effect compression. Attractive features of this pulse source include electronically tuneable repetition rates greater than 1.5 GHz, ultra-short pulse duration (10-15 ps), and low timing jitter as measured by both harmonic analysis and single-sideband (SSB) phase noise measurements. The experimental implementation of the modelled compression scheme is discussed, including the successful removal of stimulated Brillouin scattering (SBS) through linewidth broadening by injection dithering or phase modulation. Timing jitter analysis identifies many unwanted artefacts generated by the SBS suppression methods, hence an experimental arrangement is devised (and was subsequently patented) which ensures that there are no phase modulation spikes present on the SSB phase noise spectrum over the offset range of interest for optical sampling applications, 10Hz-Nyquist. It is believed that this is the first detailed timing jitter study of a soliton-effect compression scheme. The soliton-effect compression pulses are then used to perform what is believed to be the first demonstration of optical sampling using this type of pulse source. The pulse source was also optimised for use in a novel optical metrology (range finding) system, which is being developed and patented under European Space Agency funding as an enabling technology for formation flying satellite missions. This new approach to optical metrology, known as Scanning Interferometric Pulse Overlap Detection (SIPOD), is based on scanning the optical pulse repetition rate to find the specific frequencies which allow the return pulses from the outlying satellite, i.e. the measurement arm, to overlap exactly with a reference pulse set on the hub satellite. By superimposing a low frequency phase modulation onto the optical pulse train, it is possible to detect the pulse overlap condition using conventional heterodyne detection. By rapidly scanning the pulse repetition rate to find two frequencies which provide the overlapping pulse condition, high precision optical pulses can be used to provide high resolution unambiguous range information, using only relatively simple electronic detection circuitry. SIPOD’s maximum longitudinal range measurement is limited only by the coherence length of the laser, which can be many tens of kilometres. Range measurements have been made to better than 10 microns resolution over extended duration trial periods, at measurement update rates of up to 470 Hz. This system is currently scheduled to fly on ESA’s PROBA-3 mission in 2012 to measure the intersatellite spacing for a two satellite coronagraph instrument. In summary, this thesis is believed to present three novel areas of research: the first detailed jitter characterisation of a soliton-effect compression source, the first optical sampling using such a compression source, and a novel optical metrology range finding system, known as SIPOD, which utilises the tuneable repetition rate and highly stable nature of the compression source pulses.
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King, Steven Anthony. "Sub-hertz optical frequency metrology using a single ion of 171Yb+." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:428b1f40-3b5d-475e-aebc-c062b987e3f2.
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Optical frequency standards offer the possibility of a step improvement of up to two orders of magnitude in the accuracy with which the SI second can be realised. 171Yb+ possesses two dipole-forbidden optical transitions that are promising candidates for a redefinition of the second. In this thesis, absolute frequency measurements of these two transitions are presented. A number of experimental upgrades have been implemented, which have resulted in a large reduction in both the statistical and systematic uncertainties associated with the measurements and have improved both the reliability and simplicity of the experimental setup. In particular, the replacement of two frequency-doubled Ar+-pumped Ti:sapphire lasers with extended cavity diode lasers has eliminated the downtime associated with their maintenance. Additionally, the introduction of polarisation modulation on the cooling light has allowed the residual bias magnetic field required for laser cooling to be reduced by a factor of thirty. The first measurement at the National Physical Laboratory (NPL) of the frequency of the 2S1/2 (F = 0) → 2D3/2 (F′ = 2) electric quadrupole (E2) transition at 436 nm is presented. The transition frequency was measured against a hydrogen maser using a femtosecond optical frequency comb, and was determined with a relative standard uncertainty of 1.3 × 10−14. A commercial diode-based laser system was then implemented in order to drive the 2S1/2 (F = 0) → 2F7/2 (F′ = 3) electric octupole (E3) transition at 467 nm. The laser frequency was actively stabilised to the ultra-narrow atomic absorption with a resolved linewidth of 11 Hz, allowing the acquisition of ninety hours of frequency data measured relative to the NPL’s primary frequency standard CsF2. Combined with a thorough evaluation of the systematic perturbations, the total fractional uncertainty in the absolute frequency of the transition has been reduced by a factor of twenty to 1 × 10−15. Recent complementary results from Physikalisch-Technische Bundesanstalt (PTB) show that the E3 transition in 171Yb+ has the potential to be a highly accurate and reproducible optical frequency standard, and to date these measurements demonstrate the best international agreement between trapped ion optical frequency standards.
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BARBIERI, PIERO. "High-Accuracy Optical Frequency Metrology: traceability at the 1E-17 level." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2827704.
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Oram, Richard Joseph. "An investigation of the frequency stability and passive ultra low thermal expansion glass ceramic optical cavities." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304656.
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Jaturunruangsri, Supaporn. "Evaluation of material surface profiling methods : contact versus non-contact." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/10431.
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Accurate determination of surface texture is essential for the manufacturing of mechanical components within design specifications in engineering and materials science disciplines. It is also required for any subsequent modifications to physical properties and functional aspects of the object. A number of methods are available to characterize any surface through the measurement of roughness parameters that can then be used to describe surface texture. These methods may be divided into those in that direct contact is made with the surface and those where such contact is not required. This report describes two methods approach for the surface profiling of a quartz glass substrate for step height, and tungsten substrate for roughness measure. A stylus profilometer (contact method) and vertical scanning interferometer, (VSI) or (non-contact optical method) were used for step height and roughness parameter measurements. A comparison was made with nominal values assigned to the studied surface, and conclusions drawn about the relative merits of the two methods. Those merits were found to differ, depending on the parameters under consideration. The stylus method gave better agreement of step height values for dimensions greater than a micron. Both methods showed excellent accuracy at smaller dimensions. Both methods also provided accurate average roughness values, although the VSI data significantly overestimated 35% above the peak-to-valley parameter. Likely sources and nature of such differences are discussed based on the results presented, as well as on the previous comparison studies reported in the literature. Because of such method-specific differences, the multi-technique approach used in this work for accurate surface profiling appears to be a more rational option than reliance upon a single method. Both contact and non-contact approaches have problems with specific roughness parameters, but a hybrid approach offers the possibility of combining the strengths of both methods and eliminating their individual weaknesses.
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Knuefermann, Markus M. W. "Machining surfaces of optical quality by hard turning." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/131.
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The main aim of this work was the machining by hard turning of surfaces with optical surface quality. A numerical target had been set as a surface roughness Ra = 10nm. It has been shown that achieving roughness of that magnitude by hard turning is possible. Individual work pieces exhibited the desired surface properties for short lengths at a time, but it proved to be very difficult to achieve these surfaces consistently and over longer cuts. The factors influencing the surface roughness were identified as tool defects and machine vibration in addition to the standard cutting parameters and choice of cutting tool. A model of surface generation in hard turning has been developed and good correlation between simulated and experimentally determined surface roughnesses was achieved. By introducing a material partition equation which determines the proportional contribution of material removal mechanisms in the undeformed chip a comprehensive method for assessing the contributing factors in material removal was developed. While it has been shown that surfaces in hard turning are almost exclusively generated by chip removal and plastic deformation the developed model is versatile enough to include elastic deformation of the work piece. With the help of the model of surface generation in hard turning it has been possible to attribute magnitudes of the influencing factors with respect to the cutting parameters such as feed rate and tool corner radius, and the main disturbances - tool defects and machine vibration. From this conclusions were drawn on the requirements for machine tools and cutting tools, which will need to be realised to make ultra-precision hard turning of surfaces of optical quality a feasible manufacturing process.
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Kim, Dae Wook, Chang-jin Oh, Andrew Lowman, Greg A. Smith, Maham Aftab, and James H. Burge. "Manufacturing of super-polished large aspheric/freeform optics." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622422.
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Several next generation astronomical telescopes or large optical systems utilize aspheric/freeform optics for creating a segmented optical system. Multiple mirrors can be combined to form a larger optical surface or used as a single surface to avoid obscurations. In this paper, we demonstrate a specific case of the Daniel K. Inouye Solar Telescope (DKIST). This optic is a 4.2 m in diameter off-axis primary mirror using ZERODUR thin substrate, and has been successfully completed in the Optical Engineering and Fabrication Facility (OEFF) at the University of Arizona, in 2016. As the telescope looks at the brightest object in the sky, our own Sun, the primary mirror surface quality meets extreme specifications covering a wide range of spatial frequency errors. In manufacturing the DKIST mirror, metrology systems have been studied, developed and applied to measure low-to-mid-to-high spatial frequency surface shape information in the 4.2 m super-polished optical surface. In this paper, measurements from these systems are converted to Power Spectral Density (PSD) plots and combined in the spatial frequency domain. Results cover 5 orders of magnitude in spatial frequencies and meet or exceed specifications for this large aspheric mirror. Precision manufacturing of the super-polished DKIST mirror enables a new level of solar science.
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Park, Ryeojin. "Novel Applications Using Maximum-Likelihood Estimation in Optical Metrology and Nuclear Medical Imaging: Point-Diffraction Interferometry and BazookaPET." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/318827.
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This dissertation aims to investigate two different applications in optics using maximum-likelihood (ML) estimation. The first application of ML estimation is used in optical metrology. For this application, an innovative iterative search method called the synthetic phase-shifting (SPS) algorithm is proposed. This search algorithm is used for estimation of a wavefront that is described by a finite set of Zernike Fringe (ZF) polynomials. In this work, we estimate the ZF coefficient, or parameter values of the wavefront using a single interferogram obtained from a point-diffraction interferometer (PDI). In order to find the estimates, we first calculate the squared-difference between the measured and simulated interferograms. Under certain assumptions, this squared-difference image can be treated as an interferogram showing the phase difference between the true wavefront deviation and simulated wavefront deviation. The wavefront deviation is defined as the difference between the reference and the test wavefronts. We calculate the phase difference using a traditional phase-shifting technique without physical phase-shifters. We present a detailed forward model for the PDI interferogram, including the effect of the nite size of a detector pixel. The algorithm was validated with computational studies and its performance and constraints are discussed. A prototype PDI was built and the algorithm was also experimentally validated. A large wavefront deviation was successfully estimated without using null optics or physical phase-shifters. The experimental result shows that the proposed algorithm has great potential to provide an accurate tool for non-null testing. The second application of ML estimation is used in nuclear medical imaging. A high-resolution positron tomography scanner called BazookaPET is proposed. We have designed and developed a novel proof-of-concept detector element for a PET system called BazookaPET. In order to complete the PET configuration, at least two detector elements are required to detect positron-electron annihilation events. Each detector element of the BazookaPET has two independent data-acquisition channels. One of the detector channels is a 4 x 4 silicon photomultiplier (SiPM) array referred to as the SiPM-side. The SiPM-side is directly coupled to an optical window of the scintillator with optical grease. The other channel is a CCD-based gamma camera with an imaging intensifier called the Bazooka-side. Instead of coupling by direct contact like the SiPM-side, an F/1.4 lens pair is used for optical coupling. The scintillation light from the opposite optical window to the SiPM-side is imaged by the F/1.4 lens to the Bazooka-side. Using these two separate channels, we can potentially obtain high energy, temporal and spatial resolution data by associating the data outputs via several ML estimation steps. We present the concept of the system and the prototype detector element. In this work, we focus on characterizing individual detector channels, and initial experimental calibration results are shown along with preliminary performance-evaluation results. We also address the limitations and the challenges of associating the outputs of the two detector channels.
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Ceremuga, Joseph Thomas II. "Optimizing inspection of high aspect ratio microstructure using a programmable optical microscope." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5394.
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Ceremuga, Joseph Thomas. "Optimizing inspection of high aspect ratio microstructure using a programmable optical microscope." Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180101/unrestricted/ceremuga%5Fjoseph%5Ft%5F200312%5Fms.pdf.
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Su, Rong. "Assessment of optical coherence tomography for metrology applications in high-scattering ceramic materials." Licentiate thesis, KTH, Mätteknik och optik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98621.
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Large-scale and cost-effective manufacturing of ceramic micro devices based on tape stacking requires the development of inspection systems to perform high-resolution in-process quality control of embedded manufactured cavities, metal structures and defects. In this work, alumina ceramic samples are evaluated by optical coherence tomography (OCT) operating at 1.3μm wavelength and some dimensional data are obtained by dedicated image processing and segmentation. Layer thicknesses can be measured and laser-machined channels can be verified embedded at around 100μm depth. Moreover, detection of internal defects is enabled. Monte Carlo ray tracing simulations are employed to analyze the abilities of OCT in imaging of the embedded channels. The light scattering mechanism is studied for the alumina ceramics, and different scattering origins and models are discussed. The scattering parameters required as input data for simulations are evaluated from the integrating sphere measurements of collimated and diffuse transmittance spectra using a reconstruction algorithm based on refined diffusion approximation approach.QC 20120628
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Humphreys, Peter Conway. "Experimental and theoretical techniques for quantum-enhanced metrology and optical quantum information processing." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:57e942ac-f6f1-43fe-ac77-ef85b7db85ca.
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Over the last few decades, quantised excitations of the electromagnetic field have proven to be an ideal system with which to investigate and harness quantum optical phenomena. The techniques developed have enabled fundamental tests of quantum mechanics as well as practical applications in quantum metrology and quantum information processing. Advancing to larger-scale entangled quantum systems will open up new regimes of quantum many-body physics, allowing us to probe the limits of quantum mechanics and enabling truly quantum-enhanced technologies. However, moving towards this goal will require further experimental and theoretical innovations. The work described in this thesis focuses on several different aspects of optical quantum information, but are ultimately all linked by this long-term aim. The first part of this thesis describes a novel method for strain-based active control of quantum optical circuits and a new method for the characterisation of high efficiency detectors. Building on this, I discuss in detail two different fields of quantum optics that stand to benefit from these techniques. I initially consider quantum-enhanced metrology, including work aimed towards demonstrating a truly better-than-classical phase measurement, and a theoretical exploration of multiple-phase estimation. Finally, I focus on linear-optical quantum information processing, exploring in detail the use of time-frequency encodings for quantum computing.
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Clark, David C. "Digital Holographic Measurement of Nanometric Optical Excitation on Soft Matter by Optical Pressure and Photothermal Interactions." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4299.
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In this dissertation we use digital holographic quantitative phase microscopy to observe and measure phase-only structures due to induced photothermal interactions and nanoscopic structures produced by photomechanical interactions. Our use of the angular spectrum method combined with off-axis digital holography allows for the successful hologram acquisition and processing necessary to view these phenomena with nanometric and, in many cases, subnanometric precision. We show through applications that this has significance in metrology of bulk fluid and interfacial properties.
Our accurate quantitative phase mapping of the optically induced thermal lens in media leads to improved measurement of the absorption coefficient over existing methods. By combining a mathematical model describing the thermal lens with that describing the surface deformation effect of optical radiation pressure, we simulate the ability to temporally decouple the two phenomena. We then demonstrate this ability experimentally as well as the ability of digital holography to clearly distinguish the phase signatures of the two effects. Finally, we devise a pulsed excitation method to completely isolate the optical pressure effect from the thermal lensing effect.
We then develop a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase imaging technique to track a propagating nanometric capillary disturbance. We demonstrate the method's ability to accurately measure the surface energy of pure media and chemical monolayers formed by surfactants with good agreement to published values. We discuss the possible adaptation of this technique to applications for living biological cell membranes.
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Zobrist, Tom L. "Application of laser tracker technology for measuring optical surfaces." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195326.
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The pages of this dissertation detail the development of an advanced metrology instrument for measuring large optical surfaces. The system is designed to accurately guide the fabrication of the Giant Magellan Telescope and future telescopes through loose-abrasive grinding. The instrument couples a commercial laser tracker with an advanced calibration technique and a set of external references to mitigate a number of error sources. The system is also required to work as a verification test for the GMT principal optical interferometric test of the polished mirror segment to corroborate the measurements in several low-order aberrations. A set of system performance goals were developed to ensure that the system will achieve these purposes. The design, analysis, calibration results, and measurement performance of the Laser Tracker Plus system are presented in this dissertation.
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Su, Tianquan. "Asphercial Metrology for Non-Specular Surfaces with the Scanning Long-Wave Optical Test System." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/347221.
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Aspherical optics are increasingly used these days. The application of aspherical surfaces on large, astronomical telescope mirrors brings challenge to the fabrication. Since the surface radius of curvature varies across the surface, the grinding/polishing tool needs to change its shape when working on different parts of the surface, making surface error more easily embedded into the surface. Therefore, a tighter test-fab loop is needed to guide the fabrication process. To maximize the accuracy during the grinding of the surface and to minimize the working time in the polishing stage, a better metrology device that can measure rough surface is needed to guide the grinding process. Scanning long-wave optical test system (SLOTS) is designed to meet this demand by providing accurate, fast, large dynamic range, and high spatial resolution measurements on rough optical surfaces (surface rms roughness<1.7 µm).SLOTS is a slope measuring deflectometry system that works like a reversed wire test. It measures the reflection of the infrared light off the test surface, and calculates the local slope of the test surface. The surface sag/height is obtained through integration. During the test, a heated metal ribbon radiates long-wave infrared light that is reflected by the test surface. A thermal imaging camera records the reflected light. The ribbon is scanned in two orthogonal directions. From the variation of the irradiance recorded by the camera, slope maps of the test surface can be retrieved in the two orthogonal directions. SLOTS is a combination of tradition slope measurement and modern technology, processing advantages from both parts. It measures surface slope, so there is no need for null optics. It uses an uncooled thermal imaging camera that is made with high resolution and high sensitivity. The linear stage used to scan the hot ribbon has long travel, small resolution, and high accuracy. Both the camera and stage enable SLOTS a large dynamic range and high sensitivity. SLOTS has successfully guided the grinding process of the primary mirror of Daniel K. Inouye Solar Telescope. This mirror is a 4-meter diameter off-axis parabola (OAP). Its largest aspherical departure is 8 mm. SLOTS is able to measure it without any null optics. Under the guidance of SLOTS, the surface shape was controlled to be 1 µm rms within designed shape (with astigmatism removed) at 0.7 µm rms surface roughness (12 µm loose abrasive grits).
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Mauron, Pascal. "Reliability and lifetime of optical fibres and fibre bragg gratings for metrology and telecommunications /." Lausanne, 2001. http://library.epfl.ch/theses/?nr=2339.
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Predehl, Katharina. "A 920 km optical fiber link for frequency metrology at the 19th decimal place." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-150213.
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Audley, Heather E. [Verfasser]. "Preparing for LISA pathfinder operations : characterisation of the optical metrology system / Heather E. Audley." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2015. http://d-nb.info/1070283452/34.
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Dixit, Dhairya J. "Optical Metrology for Directed Self-assembly Patterning Using Mueller Matrix Spectroscopic Ellipsometry Based Scatterometry." Thesis, State University of New York at Albany, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3718824.
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The semiconductor industry continues to drive patterning solutions that enable devices with higher memory storage capacity, faster computing performance, lower cost per transistors, and higher transistor density. These developments in the field of semiconductor manufacturing along with the overall minimization of the size of transistors require cutting-edge metrology tools for characterization.
Directed self-assembly (DSA) patterning process can be used to fabricate nanoscale line-space patterns and contact holes via thermodynamically driven micro-phase separation of block copolymer (BCP) films with boundary constraints from guiding templates. Its main advantages are high pattern resolution (~10 nm), high throughput, no requirement of a high-resolution mask, and compatibility with standard fab-equipment and processes. Although research into DSA patterning has demonstrated a high potential as a nanoscale patterning process, there are critical challenges that must be overcome before transferring DSA into high volume manufacturing, including achievement of low defect density and high process stability. For this, advances in critical dimension (CD) and overlay measurement as well as rapid defect characterization are required. Both scatterometry and critical dimension-scanning electron microscopy (CD-SEM) are routinely used for inline dimensional metrology. CD-SEM inspection is limited, as it does not easily provide detailed line-shape information, whereas scatterometry has the capability of measuring important feature dimensions including: line-width, line-shape, sidewall-angle, and thickness of the patterned samples quickly and non-destructively.
The present work describes the application of Mueller matrix spectroscopic ellipsometry (MMSE) based scatterometry to optically characterize DSA patterned line- space grating and contact hole structures fabricated with phase-separated polystyrene-b-polymethylmethacrylate (PS-b-PMMA) at various integration steps of BCP DSA based patterning process. This work focuses on understanding the efficacy of MMSE base scatterometry for characterizing complex DSA structures. For example, the use of symmetry-antisymmetry properties associated with Mueller matrix (MM) elements to understand the topography of the periodic nanostructures and measure defectivity. Simulations (the forward problem approach of scatterometry) are used to investigate MM elements’ sensitivity to changes in DSA structure such as one vs. two contact hole patterns and predict sensitivity to dimensional changes. A regression-based approach is used to extract feature shape parameters of the DSA structures by fitting simulated optical spectra to experimental optical spectra. Detection of the DSA defects is a key to reducing defect density for eventual manufacturability and production use of DSA process. Simulations of optical models of structures containing defects are used to evaluate the sensitivity of MM elements to DSA defects. This study describes the application of MMSE to determine the DSA pattern defectivity via spectral comparisons based on optical anisotropy and depolarization. The use of depolarization and optical anisotropy for characterization of experimental MMSE data is a very recent development in scatterometry. In addition, reconstructed scatterometry models are used to calculate line edge roughness in 28 nm pitch Si fins fabricated using DSA patterning process.
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Lim, Ryan S. (Ryan Seungwook). "Staged attitude-metrology pointing control and parametric integrated modeling for space-based optical systems." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35574.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 155-158).
The quest for higher sensitivity and finer angular resolution in astronomy demands larger and more complex space imaging systems. This thesis presents the concepts developed for two different technologies that have the potential to contribute in improving the performance of space imaging systems. The first technology is precision pointing control technology, which can provide fine optical control operating in conjunction with coarse formation flying attitude control in order to meet the stringent optical requirements. This will potentially enable a long baseline Formation Flying Interferometer (FFI) such as NASA's Terrestrial Planet Finder (TPF). The concept for precision pointing control was realized by a testbed called the Precision Pointing Optical Payload (PPOP). The design and implementation of the PPOP are described, followed by an experimental demonstration of staged pointing control. The global metrology system of the Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) provides coarse attitude control, whereas the PPOP provides fine pointing control using a set of fast steering mirrors. The second technology investigates parametric integrated modeling of space telescopes.
(cont.) This technology provides a design tool for examining alternative telescope architectures and identifying favorable architectures at an early stage of the design lifecycle. The MIT Space Systems Laboratory (MIT-SSL) is currently developing a parametric integrated model for a Modular Optical Space Telescope (MOST). This thesis provides an overview of the MOST model, with emphasis on the development of the optics sub-model. ZEMAX is used for calculating the wave front error based on the Zernike sensitivity analysis. A data interface between ZEMAX and MATLAB has been developed, which makes the process of performing the Zernike sensitivity analysis automated.
by Ryan S. Lim.
S.M.
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Harper, Matthew R. "Control and measurement of ultrafast pulses for pump/probe-based metrology." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/430.
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Lim, Jinkang. "All-fiber frequency comb employing a single walled carbon nanotube saturable absorber for optical frequency metrology in near infrared." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/7423.
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Doctor of PhilosophyDepartment of Physics
Brian R. Washburn
Optical frequency combs produced by mode-locked fiber lasers are useful tools for high precision frequency metrology and molecular spectroscopy in a robust and portable format. We have specifically investigated erbium doped fiber mode-locked lasers that use single-walled carbon nanotubes as a saturable absorber. We have, for the first time, developed and phase- stabilized a carbon nanotube fiber laser (CNFL) frequency comb. The carbon nanotube saturable absorber, which was fabricated using an optically driven deposition method, permits a high repetition frequency (>150 MHz) since an optical nonlinearity of fibers is not used for mode-locking. The CNFL comb combined with a parabolic pulse erbium doped fiber amplifier (EDFA) has shown a compact, robust, and cost-effective supercontinuum source. The amplified pulse from the parabolic pulse EDFA was compressed with a hollow-core photonic bandgap fiber, which produced a wave-breaking-free pulse with an all-fiber set-up. The stabilized comb has demonstrated a fractional instability of 1.2 ×10[superscript]-11 at 1 sec averaging time, the reference-limited instability. We have performed optical frequency metrology with the CNFL comb and have measured an optical frequency, P(13) which is a molecular overtone transition of C2H2. The measured frequency has shown a good agreement with the known value within an uncertainty of 10 kHz. In order to extend the application of the CNFL comb such as multi-heterodyne dual comb spectroscopy, we have investigated the noise of the CNFL comb and particularly, the broad carrier envelope offset frequency (f[subscript]0) linewidth of the CNFL comb. The primary noise source is shown to be white amplitude noise on the oscillator pump laser combined with the sensitivity of the mode-locked laser to pump power fluctuations. The control bandwidth of f[subscipt]0 was limited by the response dynamics of the CNFL comb. The significant reduction of comb noise has been observed by implementing a phase-lead compensation to extend control bandwidth of the comb and by reducing the pump relative intensity noise simultaneously. Therefore the f[subscipt]0 linewidth has been narrower from 850 kHz to 220 kHz. The integrated phase noise for the f[subscipt]0 lock is 1.6 radians from 100 Hz to 102 kHz.
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Kaune, Brigitte [Verfasser]. "In-orbit Stability Analysis of the LISA Pathfinder Optical Metrology: Photoreceivers and Polarisation / Brigitte Kaune." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://d-nb.info/1233426516/34.
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