Searched for: subject%3A%22Lenses%22
(1 - 20 of 30)

Pages

document
Coco Martin, C.M. (author), Hu, Weiya (author), Cavallo, D. (author)
This work aims to provide guidelines on the design of wideband flat lenses based on artificial dielectric layers (ADLs). Planar lenses based on metasurfaces are typically narrowband, due to the phase wrapping over the period of 2\pi that is strongly frequency-dependent. On the contrary, true-time-delay (TTD) planar lenses, which do not resort...
journal article 2024
document
Hu, Weiya (author), Coco Martin, C.M. (author), Cavallo, D. (author)
A semi-analytical method is presented for the design of gradient index (GRIN) flat lenses. Closed-form expressions are derived to define the refractive index distribution of the lens, for several cases: collimating lenses with on-axis feed, collimating lenses with off-axis feed, lenses converting spherical wavefronts with different...
journal article 2024
document
Zhang, H. (author), Dabironezare, Shahab Oddin (author), Baselmans, J.J.A. (author), Llombart, Nuria (author)
Large format focal plane arrays (FPAs) of dielectric lenses are promising candidates for wide field-of-view submillimeter imagers. In this work, we optimize the scanning gain of such imagers via shaping lens surfaces. We develop an optimization procedure using a field correlation technique between the fields generated by a reflector on the...
journal article 2023
document
Cavallo, D. (author)
Artificial Dielectric Layers (ADLs) have recently been exploited to improve the radiation and impedance performance of integrated antennas at millimeter wave (mmWave) and terahertz (THz) frequencies. The ADLs are composed by layers of sub-wavelength periodic metal patches that can be arranged within a host medium to synthesize an equivalent...
conference paper 2023
document
Gaspar Silva, Jose Rui (author), Finkel, M. (author), Laauwen, Wouter M. (author), Yates, S.J.C. (author), Mirzaei, B. (author), Vercruyssen, N. (author), Young, Abram (author), Walker, Christopher (author), Gao, J.R. (author)
We have simulated and measured the beam properties of lens-antenna coupled hot electron bolometer mixers at a few supra-terahertz frequencies between 1.4 and 5.3 THz. The quasi-optical structures consist of an elliptical lens and a logarithmic spiral antenna. The model used for our simulations consists of a finite-element analysis to simulate...
journal article 2023
document
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
document
Gottmer, Leila (author)
In this thesis, an efficient optimization method is described for synthesizing lens antennas fabricated in low permittivity plastic materials to achieve wide scanning performances. The method is based on an antenna in reception representation. The optimized parameters are the location and orientation of the antenna feeder, lens angular region...
master thesis 2022
document
Pascual Laguna, A. (author), Cavallo, D. (author), Baselmans, J.J.A. (author), Llombart, Nuria (author)
This communication proposes a broadband and efficient integrated focal plane array solution based on a near-field focused connected array of slots. The focused aperture provides: 1) broadband and highly efficient illumination of the quasi-optical system and 2) scanning capabilities within a focusing system. The connected array antenna in turn...
journal article 2022
document
Gasparsilva, Jose Rui (author), Finkel, M. (author), Laauwen, Wouter (author), Westerweld, Menno (author), More, Nikhil (author), Young, Abram (author), Kulesa, Craig (author), Walker, Christopher (author), Van der Tak, Floris (author), Gao, J.R. (author)
We report a high accuracy pointing technique for quasi-optical hot electron bolometer (HEB) mixers in focal-plane arrays designed to operate at 1.4, 1.9, and 4.7 THz. The high accuracy pointing is achieved by prealignment of a HEB chip to a lens, measuring the angular error of each mixer in an array assembly, and then realignment of the chip...
journal article 2022
document
Theuwissen, A.J.P.A.M. (author)
This article focuses on the angular dependency of the light sensitivity of a commercially available CMOS camera with a global shutter (storage node (SG) in the charge domain) and shared pixel architecture. The angular dependency is characterized as a function of both the wavelength and the angle of incidence of the incoming light. The...
journal article 2022
document
Kleynen, Wouter (author)
A black hole is an object in space where the pull of its gravity is so strong<br/>that no light can escape. This notion gives rise to the phenomenon called<br/>gravitational lensing which is the effect where light is being bent by a massive<br/>object, in our case a black hole. With these two concepts in mind we are<br/>able to formulate the...
bachelor thesis 2021
document
van Schelven, R.M. (author), Fiorellini Bernardis, A. (author), Sberna, P.M. (author), Neto, A. (author)
Semiconductor (SC)-based bulk absorbers operating in the (sub-) THz range are discussed. The conductivities of the bulk media are described by the Drude model for electron gas where the electron density is controlled. The Drude model predicts the existence of two frequencies of interest: one associated with the scattering time of the electrons...
journal article 2021
document
López-Marín, Antonio (author), Springeling, Geert (author), Beurskens, Robert (author), Van Beusekom, Heleen (author), van der Steen, A.F.W. (author), Koch, Arjun D. (author), Bouma, Brett E. (author), Huber, Robert A. (author), Van Soest, Gijs (author), Wang, Tianshi (author)
In this study, we demonstrate a 12x36 mm motorized capsule for OCT imaging of the esophagus. The capsule produces unobstructed images by using a distal reflector design, thus avoiding shadow caused by the motor wires. The motor synchronous control enables three working modes: circumferential imaging, angular sector imaging and accurate beam...
conference paper 2020
document
Platschorre, Arthur (author)
This Bachelor thesis is on Covariant Emergent Gravity (CEG): a covariant formulation by Sabine Hossenfelder of the ideas of Erik Verlinde on gravity as an emergent force. In this work, the ideas of Erik Verlinde are presented as well as the field equations of CEG. The aim of this thesis is to find experimentally verifiable results for CEG. From...
bachelor thesis 2019
document
Abreu Vieira Viula, R.J. (author), Hordijk, G.J. (author)
The calculation of field-of-view luminance based metrics for visual discomfort from glare evaluation in real scenes via HDR (High Dynamic Range) luminance capture does generally require the use of wide view fisheye lenses. This paper presents an easy to implement and low-cost method to estimate a fisheye lens’ total field-of view and projection...
conference paper 2019
document
Jovic, A. (author), Uto, T. (author), Hei, K. (author), Sancho, Juan (author), Sanchez, Nuria (author), Zinoviev, Kirill (author), Rubio, Jose L. (author), Margallo, Eduardo (author), Pandraud, G. (author), Sarro, Pasqualina M (author)
A highly miniaturized, single-chip, large scanning range MOEMS scanner is demonstrated. This intrinsically-aligned, monolithically integrated device uses small angular displacement to provide a linear scanning range of 2000 μm in the lateral and 1000 μm in the vertical direction, at a working distance of 2 cm, with an average operating power...
conference paper 2018
document
van Berkel, S.L. (author), Malotaux, E.S. (author), Cavallo, D. (author), Spirito, M. (author), Neto, A. (author), Llombart, Nuria (author)
The optical performance of a wideband double bowtie slot antenna, implemented in 28nm CMOS technology, is evaluated. The antenna serves as a verification antenna for an uncooled single-pixel radiometer operating from 200 GHz to 600 GHz. The performance is evaluated in terms of radiometric pattern that is derived from the measured radiation...
conference paper 2018
document
Bruining, J.G. (author)
Strabismus, or “crossed eyes”, is a condition in which the eyes do not line up in the same direction when focusing on an object. The DAISY is a device that is designed to measure Strabismus on young children, this has to be done quickly in order to not lose the attention of the child. In order to calibrate the main measuring principle, the...
master thesis 2017
document
Yurduseven, O. (author), Bosma, S. (author), Endo, A. (author), Neto, A. (author), Llombart, Nuria (author)
DESHIMA (Deep Spectroscopic High-redshift Mapper) is an instrument aiming at efficiently making spectroscopic redshift measurements of sub-mm wave galaxies (SMGs), thereby providing about the formation and the evolution of stars and galaxies. The aim of this work is to provide a preliminary study into the design of a wideband leaky lens antenna...
conference paper 2017
document
Bueno Lopez, J. (author), Yurduseven, O. (author), Llombart, Nuria (author), Yates, S.J.C. (author), Neto, A. (author), Baselmans, J.J.A. (author)
This contribution presents the design and sub-mm wave measurements of a wideband dual polarized leaky lens antenna coupled to kinetic inductance detector (KIDs) to be specifically used for tightly spaced focal plane arrays. The antenna is planar and composed by two crossed slots, fed by two orthogonal coplanar waveguide (CPW) lines. In...
conference paper 2017
Searched for: subject%3A%22Lenses%22
(1 - 20 of 30)

Pages