Tesis sobre el tema "Laser beam steering"
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Bas, Derek. "Laser Beam Steering with Thin Film GaAs on Plastic". Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1277119321.
Texto completoHällstig, Emil. "Nematic Liquid Crystal Spatial Light Modulators for Laser Beam Steering". Doctoral thesis, Uppsala University, Quantum Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4693.
Texto completoLaser beam control is important in many applications. Phase modulating spatial light modulators (SLMs) can be used to electronically alter the phase distribution of an optical wave-front and thus change the direction and shape of a laser beam. Physical constraints set limitations to the SLM and an ideal phase distribution can usually not be realised. In order to understand how such components can be used for non-mechanical beam control three nematic liquid crystal (NLC) SLMs have been thoroughly characterised and modelled.
The pixel structure and phase quantisation give a discrepancy between ideal and realised phase distributions. The impact on beam steering capability was examined by measurements and simulations of the intensity distribution in the far-field.
In two of the studied SLMs the pixel period was shorter than the thickness of the LC layer giving the optical phase shift. This results in a so-called “fringing field”, which was shown to degrade the phase modulation and couple light between polarisation modes. The deformation of the LC was simulated and a finite-difference time-domain (FDTD) algorithm was used to calculate how polarised light propagates through the optically anisotropic SLM.
Non-mechanical beam steering and tracking in an optical free-space communication link were demonstrated. Continual optimisation of the steering angle was achieved by feedback from a video camera.
The optical properties of the SLM in the time period right after a voltage update were studied. It was shown how light is redistributed between orders during the switching from one blazed grating to another. By appropriate choice of the blazed gratings the effects on the diffraction efficiency can be minimised.
The detailed knowledge of the SLM structure and its response to electronic control makes it possible to predict and optimise the device performance in future systems.
Hällstig, Emil. "Nematic liquid crystal spatial light modulators for laser beam steering /". Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4693.
Texto completoLiu, Yifan. "The True-Time-Delay (TTD) Laser Beam Steering System Design Based on Fourier Cell". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1237915468.
Texto completoSANTAGATA, ROSA. "Sub-nanometer length metrology for ultra-stable ring laser gyroscopes". Doctoral thesis, Rosa Santagata, 2015. http://hdl.handle.net/11365/1004514.
Texto completoEvans, Jonathan W. "Beam Switching of an Nd:YAG Laser Using Domain Engineered Prisms in Magnesium Oxide Doped Congruent Lithium Niobate". University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1281366442.
Texto completoBugoffa, Salaheddeen G. "Acousto-Optic Scanning and Reflection Sensing for Large Area Object Search and Recovery". University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1470257122.
Texto completoShi, Lei. "Tunable liquid crystal polarization gratings". [Kent, Ohio] : Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1258988951.
Texto completoTitle from PDF t.p. (viewed Apr. 22, 2010). Advisor: Philip Bos. Keywords: Liquid crystal; beam steering; polarization gratings; diffraction efficiency; decentered microlens array. Includes bibliographical references (p. 216-219).
Tran, Tuan-Anh. "Multiple-input multiple-output optical wireless communications". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:094fbe23-88c3-49c4-b64b-a1de40674123.
Texto completoKhan, Sajjad. "Liquid Crystal Optics for Communications, Signal Processing and 3-D Microscopic Imaging". Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3389.
Texto completoPh.D.
Optics and Photonics
Optics
Reardon, Christopher P. "Free space optical interconnects for speckled computing". Thesis, St Andrews, 2009. http://hdl.handle.net/10023/698.
Texto completoSun, Fei. "Thermally induced beam steering in high power diode-pumped planar waveguide lasers". Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/94.
Texto completoPenner, Robert Scott. "Focusing, wavelength tuning, beam steering and beam shaping of circular grating surface emitting distributed Bragg reflector lasers". Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284042.
Texto completoFrench, Kyle J. "Growth of Optical Quality Lead Magnesium Niobate-Lead Titanate Thick Films". University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1575993750125728.
Texto completoTanagardi, Mehmet. "Radiation Pattern Reconfigurable Horn Antenna Based on Parasitic Layer Concept". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7623.
Texto completoAli, Mohamed Ali Sayed Ahmed Ahmed. "Développement de nouveaux composants passifs multicouches et l'implémentation d'une matrice de Butler large-bande et compacte en technologie GIS". Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0027/document.
Texto completoMultibeam antennas have become a key element in nowadays wireless communication systems where increased channel capacity, improved transmission quality with minimum interference and multipath phenomena are severe design constraints. These antennas are classified in two main categories namely adaptive smart antennas and switched-beam antennas. Switched-beam antennas consist of an elementary antenna array connected to a Multiple Beam Forming Network (M-BFN). Among the different M-BFNs, the Butler matrix has received particular attention as it is theoretically lossless and employs the minimum number of components to generate a given set of orthogonal beams (provided that the number of beams is a power of 2). However, the Butler matrix has a main design problem which is the presence of path crossings that has been previously addressed in different research works. Substrate Integrated Waveguide (SIW) features interesting characteristics for the design of microwave and millimetre-wave integrated circuits. SIW based components combine the advantages of the rectangular waveguide, such as the high Q factor (low insertion loss) and high power capability while being compatible with low-cost PCB and LTCC technologies. Owing to its attractive features, the use of SIW technology appears as a good candidate for the implementation of BFNs. The resulting structure is therefore suitable for both waveguide-like and planar structures. In this thesis, different novel passive components (couplers and phase shifters) have been developed exploring the multi-layer SIW technology towards the implementation of a two-layer compact 4×4 Butler matrix offering wideband performances for both transmission magnitudes and phases with good isolation and input reflection characteristics. Different techniques for the implementation of wideband fixed phase shifters in SIW technology are presented. First, a novel waveguide-based CRLH structure is proposed. The structure is based on a single-layer waveguide with shunt inductive windows (irises) and series transverse capacitive slots, suitable for SIW implementations for compact phase shifters. The structure suffers relatively large insertion loss which remains however within the typical range of non-lumped elements based CRLH implementations. Second, the well-known equal length, unequal width SIW phase shifters is discussed. These phase shifters are very adapted for SIW implementations as they fully exploit the flexibility of the SIW technology in different path shapes while offering wideband phase characteristics. To satisfy good return loss characteristics with this type of phase shifters, the length has to be compromised with respect to the progressive width variations associated with the required phase shift values. A twolayer, wideband low-loss SIW transition is then proposed. The transition is analyzed using its equivalent circuit model bringing a deeper understanding of its transmission characteristics for both amplitude and phase providing therefore the basic guidelines for electromagnetic optimization. Based on its equivalent circuit model, the transition can be optimized within the well equal-length SIW phase shifters in order to compensate its additional phase shift within the frequency band of interest. This twolayer wideband phase shifter scheme has been adopted in the final developed matrix architecture.This transition is then exploited to develop a three-layer, multiply-folded waveguide structure as a good candidate for compensated-length, variable width, low-loss, compact wideband phase shifters in SIW technology. Novel two-layer SIW couplers are also addressed. For BFNs applications, an original structure for a two-layer 90° broadband coupler is developed. The proposed coupler consists of two parallel waveguides coupled together by means of two parallel inclined-offset resonant slots in their common broad wall. A complete parametric study of the coupler is carried out including the effect of the slot length, inclination angle and offset on both the coupling level and the transmission phase. The first advantage of the proposed coupler is providing a wide coupling dynamic range by varying the slot parameters allowing the design of wideband SIW Butler matrix in two-layer topology. In addition, previously published SIW couplers suffer from direct correlation between the transmission phase and the coupling level, while the coupler, hereby proposed, allows controlling the transmission phase without significantly affecting the coupling level, making it a good candidate for BFNs employing different couplers, such as, the Nolen matrix. A novel dual-band hybrid ring coupler is also developed in multi-layer Ridged SIW (RSIW) technology. This coupler has been jointly developed with Tarek Djerafi in a collaboration scenario with Prof. Ke Wu from the Ecole Polytechnique de Montréal. The coupler has an original structure based on two concentric rings in RSIW topology with the outer ring periodically loaded with radial, stub-loaded transverse slots. A design procedure is presented based on the Transverse Resonance Method (TRM) of the ridged waveguide together with the simple design rules of the hybrid ring coupler. A C/K dual band coupler with bandwidths of 8.5% and 14.6% centered at 7.2 GHz and 20.5 GHz, respectively, is presented. The coupler provides independent dual band operation with low-dispersive wideband operation. Finally, for the Butler matrix design, the two-layer SIW implementation is explored through a two-fold enhancement approach for both the matrix electrical and physical characteristics. On the one hand, the two-layer topology allows an inherent solution for the crossing problem allowing therefore more flexibility for phase compensation over a wide frequency band. This is achieved by proper geometrical optimization of the surface on each layer and exploiting the SIW technology in the realization of variable width waveguides sections with the corresponding SIW bends. On the other hand, the two-layer SIW technology is exploited for an optimized space saving design by implementing common SIW lateral walls for the matrix adjacent components seeking maximum size reduction. The two corresponding 4×4 Butler matrix prototypes are optimized, fabricated and measured. Measured results are in good agreement with the simulated ones. Isolation characteristics better than -15 dB with input reflection levels lower than -12 dB are experimentally validated over 24% frequency bandwidth centered at 12.5 GHz. Measured transmission magnitudes and phases exhibit good dispersive characteristics of 1dB, around an average value of -6.8 dB, and 10° with respect to the theoretical phase values, respectively, over the entire frequency band
Samantaray, Swastik. "Robust Adaptive Control of a Laser Beam System for Static and Moving Targets". Thesis, 2016. http://hdl.handle.net/2005/3204.
Texto completoCox, Wesley. "Magnetic steering of the ion beam in the Helicon Double Layer Thruster". Phd thesis, 2010. http://hdl.handle.net/1885/150366.
Texto completoZakariya, Abdullah. "Monolithically Integrated Broadly Tunable Light Emitters based on Selectively Intermixed Quantum Wells". Doctoral diss., 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6210.
Texto completoPh.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering