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Now showing items 141-150 of 343
Dissertation
Model Calculations for Characterisation and Implementation of Vertical Thin-Layer Structures with Distributed Cavity Mode for Filter and Laser Applications
(2018-04-11)
This work focusses on the approach of optical thin-layer filters with distributed cavity mode. Fabry-Pérot filters own a single cavity layer in the centre of the stack. In contrast, with chirped filter approach the cavity thickness is distributed over several layers. Model calculation results are applied to characterise the properties of the spectrum and the electric field of chirped filters. The aim of distributing the cavity within the filter stack is to distribute the electric field in the resonance case (transmission ...
Dissertation
Air-gap based vertical cavity micro-opto-electro-mechanical Fabry-Perot filters
(2006-03-02)
Mikrooptische Filter sind heutzutage in vielen Bereichen in der Telekommunikation unersetzlich. Wichtige Einsatzgebiete sind aber auch spektroskopische Systeme in der Medizin-, Prozess- und Umwelttechnik. Diese Arbeit befasst sich mit der Technologieentwicklung und Herstellung von luftspaltbasierenden, vertikal auf einem Substrat angeordneten, oberflächenmikromechanisch hergestellten Fabry-Perot-Filtern. Es werden zwei verschiedene Filtervarianten, basierend auf zwei verschiedenen Materialsystemen, ausführlich ...
Dissertation
Patent DE10 2004 037 519 B4 “Sensor Process and Device for Determining a Physical Value“. A Proof of Concept
(2010-06-11)
At present, a fraction of 0.1 - 0.2% of the patients undergoing surgery become aware during the process. The situation is referred to as anesthesia awareness and is obviously very traumatic for the person experiencing it. The reason for its occurrence is mostly an insufficient dosage of the narcotic Propofol combined with the incapability of the technology monitoring the depth of the patient’s anesthetic state to notice the patient becoming aware.
A solution can be a highly sensitive and selective real time monitoring ...
Dissertation
Large-Size AlGaN/GaN HEMT Large-Signal Electrothermal Characterization and Modeling for Wireless Digital Communications
(2012-03-29)
The rapid growth in high data rate communication systems has introduced new high spectral efficient modulation techniques and standards such as LTE-A (long term evolution-advanced) for 4G (4th generation) systems. These techniques have provided a broader bandwidth but introduced high peak-to-average power ratio (PAR) problem at the high power amplifier (HPA) level of the communication system base transceiver station (BTS). To avoid spectral spreading due to high PAR, stringent requirement on linearity is needed which ...
Dissertation
Micro-electromechanical structural design and optimization of vertical cavity photonic devices with wide continuous tuning
(2005-03-11)
Diese Arbeit umfaßt das elektromechanische Design und die Designoptimierung von weit durchstimmbaren optischen multimembranbasierten Bauelementen, mit vertikal orientierten Kavitäten, basierend auf der Finiten Element Methode (FEM). Ein multimembran InP/Luft Fabry-Pérot optischer Filter wird dargestellt und umfassend analysiert. In dieser Arbeit wird ein systematisches strukturelles Designverfahren dargestellt. Genaue analytische elektromechanischer Modelle für die Bauelemente sind abgeleitet worden. Diese können ...
Dissertation
Development of hybrid UV VCSEL with organic active material and dielectric DBR mirrors for medical, sensoric and data storage applications
(2009-10-19)
Lasers play an important role for medical, sensoric and data storage devices. This thesis is focused on design, technology development, fabrication and characterization of hybrid ultraviolet Vertical-Cavity Surface-Emitting Lasers (UV VCSEL) with organic laser-active material and inorganic distributed Bragg reflectors (DBR).
Multilayer structures with different layer thicknesses, refractive indices and absorption coefficients of the inorganic materials were studied using theoretical model calculations. During the ...
Dissertation
Optimization-Based Robotic Manipulation for Safe Interaction with Human Operators
(2014-05-02)
This thesis investigates a method for human-robot interaction (HRI) in order to uphold productivity of industrial robots like minimization of the shortest operation time, while ensuring human safety like collision avoidance. For solving such problems an online motion planning approach for robotic manipulators with HRI has been proposed. The approach is based on model predictive control (MPC) with embedded mixed integer programming.
The planning strategies of the robotic manipulators mainly considered in the thesis ...
Dissertation
Highly Sensitive Sensor Based On Intracavity Laser Absorption Spectroscopy By Means of Relative Intensity Noise
(2011-01-07)
This thesis concerns with the main aspects of medical trace molecules detection by means of intracavity laser absorption spectroscopy (ICLAS), namely with the equirements for highly sensitive, highly selective, low price, and compact size sensor. A novel two modes semiconductor laser sensor is demonstrated. Its operation principle is based on the competition between these two modes. The sensor sensitivity is improved when the sample is placed inside the two modes laser cavity, and the competition between the two modes ...
Dissertation
Digitale Analyse periodischer und transienter Messsignale anhand von Beispielen aus der optischen Präzisionsmesstechnik
(2018-07-26)
Optische 3D-Präzisionsmessverfahren, wie Weißlichtinterferometrie oder konfokale Mikroskopie, die eine Höhenauflösung bis in den Subnanometerbereich sowie sehr kurze Messzeiten von unter einer Sekunde erreichen, haben sich in den letzten Jahrzehnten in industriellen und wissenschaftlichen Anwendungen etabliert. Der aktuelle Trend in der Industrie ist die hundertprozentige Qualitätskontrolle. Schnell und kosteneffizient lässt sich dieses Ziel nur durch die Integration der Messsysteme direkt in den Fertigungsprozess ...
Dissertation
Capturing Emergent Semantics from Social Annotation Systems
(2013-02-26)
The ongoing growth of the World Wide Web, catalyzed by the increasing possibility of ubiquitous access via a variety of devices, continues to strengthen its role as our prevalent information and commmunication medium. However, although tools like search engines facilitate retrieval, the task of finally making sense of Web content is still often left to human interpretation. The vision of supporting both humans and machines in such knowledge-based activities led to the development of different systems which allow to ...