Searched for: subject%3A%22Lens%22
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Zhang, H. (author)
In recent decades, dielectric lens antennas have been more and more adopted and developed for sensing and imaging applications at sub-millimeter (sub-mm) wavelengths because they can achieve high gain while keeping their physical size and weight acceptable at these wavelengths. More recently, as low-loss and low-cost lens materials have become...
doctoral thesis 2024
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Tan, Junyao (author)
This master thesis explores the capacity of MIMO arrays for communication in the radiative near field through antenna design. This research applies an in-house MATLAB model based on free space Green’s function to calculate the channel matrix, revealing the potential increase of capacity through the use of incoherent arrays with directive...
master thesis 2023
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Zhang, Muhan (author)
Recently, there has been an increasing demand for security in public places. As a result, non-destructive and fast millimetre-wave and submillimetre-wave imaging systems have gained more and more attention.<br/>This project is based on Concealed Objects Stand-off Real-Time Imaging for Security (CONSORTIS), which is a European next-generation...
master thesis 2023
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Hu, Weiya (author)
Flat lens antennas are convenient solutions to realize highly directive antennas for millimeter wave and terahertz frequencies. Unlike the traditional three-dimensional bulky lens antennas, flat lenses are compact, low profile, and planar structures that can be manufactured with standard multi-layer technology, e.g. printed circuit board (PCB)...
master thesis 2023
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Griffith, Kiana (author)
This thesis analyzes and describes a wearable pressure sensor to detect intraocular pressure and guide clinician diagnosis of glaucoma. Although glaucoma has many<br/>symptoms and risk factors, high intraocular pressure is the most predominant. A method to continuously and accurately record intraocular pressure measurements and fluctuations in a...
master thesis 2023
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Bechrakis Triantafyllos, Alexandros (author)
In the framework of this MSc thesis the analysis of core-shell leaky-wave lens antennas is presented, based on a combination of asymptotic and Physical Optics techniques. This study aims to develop an analysis approach which can be subsequently used for the optimization of the Fly’s Eye antenna concept, through enabling the investigation of...
master thesis 2023
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Mavropoulou, Alexandra (author)
In the framework of this MSc thesis, the analysis and design guidelines for part of the quasi-optical system of a proposed astronomical instrument, called TIFUUN, are presented. The TIFUUN instrument is an imaging spectrometer, planned to be placed in the ASTE telescope to perform ground-based astronomical observations in the mm-submm wavelength...
master thesis 2023
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Davidov, Lyuben (author)
There is a growing demand for precision and high-quality optical objectives and lenses due to their numerous advantages and uses. The market for high precision objective lenses has tremendous potential for development and is a sector that is expanding quickly. <br/><br/>Measuring the aberrations of optical systems is an essential step in the...
master thesis 2023
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Mekkes, Erik (author)
Large Language Models of code have seen significant jumps in performance recently. However, these jumps tend to accompany a notable and perhaps concerning increase in scale and costs. We contribute an evaluation of prediction performance with respect to model size by assessing the layer-wise progression for language and user-defined elements in...
bachelor thesis 2023
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Zhang, Yizhuo (author)
The urban spaces that arise as a result of urban shrinkage and decay are loosely defined (Franck &amp; Stevens, 2007). The ambiguity of these spaces provides a potential outlet for accidental or spontaneous encounters, informal activities and alternatives to our increasingly commodified, controlled and privatised 'open' urban spaces. Many...
master thesis 2023
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Hou, Z. (author)
In this thesis, we explore how lens design and optimization techniques can adapt to the design (optimization) space in order to increase the lens design efficiency. We extensively discuss the Saddle Point Construction (SPC), a method that can systematically search for new solutions, as well as replace high-dimensional searches with a discrete...
doctoral thesis 2023
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Savundranayagam, Reka (author)
In vitro neuromodulation studies play a crucial role in understanding the underlying interaction mechanisms between cells and ultrasound, which is important in the development of new therapies for various neurological disorders. Acoustic focusing, the ability to focus ultrasound at a specific focal length with high spatial resolution, provides a...
master thesis 2023
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Bosma, S. (author)
Millimeter- and submillimeter wave applications, such as point-to-point wireless communications in beyond-5G scenarios, long-range automotive radars and astronomy and astrophysics science cases from space require antennas with high-gain beams that are steerable. At lower (microwave) frequencies, fully sampled phased arrays with thousands of...
doctoral thesis 2023
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Herzog, Alexander (author), Benkner, Simon (author), Zandi, Babak (author), Buffolo, Matteo (author), van Driel, W.D. (author), Meneghini, Matteo (author), Khanh, Tran Quoc (author)
We report on the degradation mechanisms and dynamics of silicone encapsulated ultraviolet A (UV-A) high-power light-emitting diodes (LEDs), with a peak wavelength of 365nm. The stress tests were carried out for a period of 8665 hours with forward currents between 350mA and 700mA and junction temperatures up to 132°C. Depending on stress...
journal article 2023
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Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Hagen, C.W. (author), Kruit, P. (author)
To design electron lens systems, applying a fully automated optimization routine has not yet been feasible, especially for the case where the optimization has many free variables of the lens system, such as all parameters that define the geometry of the lens electrodes and the voltage of each electrode. Hence, the study of the implementation of...
conference paper 2023
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Bueno Lopez, J. (author), Sberna, P.M. (author), Fiorellini Bernardis, A. (author), Zhang, H. (author), Neto, A. (author), Llombart, Nuria (author)
State-of-the-art THz pulsed commercial systems operating over large bandwidth suffer from high dispersion or low radiation efficiency due to the poor coupling between the transmitter and receiver photoconductive antennas (PCAs). In this work, we present the fabrication and characterization of a leaky-lens PCA that has the potential to solve...
journal article 2023
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Hoogelander, M. (author), van Berkel, S.L. (author), Malotaux, E.S. (author), Alonso Del Pino, M. (author), Cavallo, D. (author), Spirito, M. (author), Llombart, Nuria (author)
This article presents the development of a focal plane array (FPA) for terahertz imaging applications with a near diffraction-limited resolution achieved through a very tight sampling of the focal plane. The antenna array is integrated with direct detectors in a 22-nm CMOS technology and operates from 200 to 600 GHz. The tight sampling of the...
journal article 2023
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van Berkel, S.L. (author), Alonso Del Pino, M. (author), Jung-Kubiak, Cecile (author), Chattopadhyay, Goutam (author)
The development of a low focal number and low-mass lens antenna is presented that enables terahertz spectroscopy applications on ultracompact platforms. The antenna operates efficiently over a 20% fractional bandwidth, from 450 to 550 GHz, with a gain of 50 dBi at 500 GHz. The antenna consists of a hyperbolic silicon lens that is placed in a...
journal article 2023
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de Koning, B. (author), Heemels, A.N.M. (author), Adam, A.J.L. (author), Möller, M. (author)
Algorithmic differentiable ray tracing is a new paradigm that allows one to solve the forward problem of how light propagates through an optical system while obtaining gradients of the simulation results with respect to parameters specifying the optical system. Specifically, the use of algorithmically differentiable non-sequential ray tracing...
journal article 2023
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Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Hagen, C.W. (author), Kruit, P. (author)
The design of electrostatic electron lenses involves the choice of many geometrical parameters for the lens electrodes as well as the choice of voltages applied to the electrodes. The purpose of the design is to focus the electrons at a specific point and to minimize the aberrations of the lens. In a previous study, genetic algorithm...
conference paper 2023
Searched for: subject%3A%22Lens%22
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