Searched for: subject:"far"
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Davis, Kristina K. (author), Yates, Stephen J.C. (author), Jellema, Willem (author), Groppi, Christopher E. (author), Baselmans, J.J.A. (author), Kohno, Kotaro (author), Baryshev, Andrey M. (author)
Complex field mapping is a powerful tool to characterize the optical performance of astronomical instruments, and has become the standard for characterizing heterodyne array cameras. Recently, an adaptation of the heterodyne beam mapping technique was demonstrated on a single pixel of a direct detector instrument. We present a novel...
journal article 2019
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Gennaretti, Massimo (author), Bernardini, Giovanni (author), Serafini, Jacopo (author), Anobile, A. (author), Hartjes, S. (author)
This paper investigates different methodologies for the evaluation of the acoustic disturbance emitted by helicopter’s main rotors during unsteady maneuvers. Nowadays, the simulation of noise emitted by helicopters is of great interest to designers, both for the assessment of the acoustic impact of helicopter flight on communities and for the...
journal article 2017
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Farmani, M. (author), Heusdens, R. (author), Pedersen, Michael Syskind (author), Jensen, Jesper (author)
We consider the problem of determining the relative position of dual-microphone sub-arrays. The proposed solution is mainly developed for binaural hearing aid systems (HASs), where each hearing aid (HA) in the HAS has two microphones at a known distance from each other. However, the proposed algorithm can effortlessly be applied to acoustic...
conference paper 2016
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Holtslag, M.C. (author)
Far offshore atmospheric conditions are favourable for wind energy purposes since mean wind speeds are relatively high (i.e., high power production) while turbulence levels are relatively low (i.e., less fatigue loads) compared to onshore conditions. Offshore wind energy, however, is still expensive compared to onshore wind energy. There is...
doctoral thesis 2016
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Khosropanah, P (author), Suzuki, T. (author), Ridder, M. L. (author), Hijmering, R. A. (author), Akamatsu, H. (author), Gottardi, L (author), Van Der Kuur, J. (author), Gao, J. (author), Jackson, B. D. (author)
SRON is developing ultra-low noise Transition Edge Sensors (TESs) based on a superconducting Ti/Au bilayer on a suspended SiN island with SiN legs for the SAFARI instrument aboard the SPICA mission. We successfully fabricated TESs with very narrow (0.5-0.7 μm) and thin (0.25 μm) SiN legs on different sizes of SiN islands using deep...
conference paper 2016
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Griffin, M (author), Baselmans, J.J.A. (author), Baryshev, AM (author), Doyle, S (author), Grim, M (author), Hargrave, P (author), Klapwijk, T.M. (author), Martin-Pintado, J (author), Monfardini, A (author), Neto, A. (author), Blazquez Valles, B. (author), Llombart Juan, N. (author)
SPACEKIDS, a European Union FP-7 project, has recently been completed. It has focused on developing kinetic inductance detector (KID) arrays and demonstrating their suitability for space applications at far infrared and submillimetre wavelengths. KID arrays have been developed for both low-background (typical of astrophysical applications)...
conference paper 2016
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Nervo, L. (author), King, A. (author), Wright, J.P. (author), Ludwig, W. (author), Reischig, P. (author), Quinta da Fonseca, J. (author), Preuss, M. (author)
A comparison of the performance of X-ray diffraction tomography, a near-field diffraction technique, and a far-field diffraction technique for indexing X-ray diffraction data of polycrystalline materials has been carried out by acquiring two sets of diffraction data from the same polycrystalline sample volume. Both approaches used in this study...
journal article 2014
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Hijmering, R.A. (author), Khosropanah, P. (author), Ridder, M. (author), Lindeman, M. (author), Gottardi, L. (author), Bruijn, M. (author), Van der Kuur, J. (author), De Korte, P. (author), Gao, J.R. (author), Hoervers, H. (author), Jackson, B. (author)
At the Netherlands Institute for Space Research (SRON) we are developing Transition Edge Sensors (TES) bolometers for the SAFARI Imaging Spectrometer on the SPICA telescope. With the current design of the SPICA telescope a background magnetic field of about a Gauss with fluctuations of a couple percent is expected. The effect of this external...
journal article 2012
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Khosropanah, P. (author), Hijmering, R.A. (author), Ridder, M. (author), Lindeman, M.A. (author), Gottardi, L. (author), Bruijn, M. (author), Van der Kuur, J. (author), de Korte, P.A.J. (author), Gao, J.R. (author), Hoevers, H. (author)
Transition edge sensors (TES) are the chosen detector technology for the SAFARI imaging spectrometer on the SPICA telescope. The TES are required to have an NEP of 2–3 × 10?19 W/? Hz to take full advantage of the cooled mirror. SRON has developed TiAu TES bolometers for the short wavelength band (30–60 ?m). The TES are on SiN membranes, in which...
journal article 2012
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Khosropanah, P. (author), Dirks, B. (author), Parra-Borderias, M. (author), Ridder, M. (author), Hijmering, R. (author), Van der Kuur, J. (author), Gottardi, L. (author), Bruijn, M. (author), Popescu, M. (author), Gao, J.R. (author), Hoevers, H. (author)
conference paper 2010
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Khosropanah, P. (author), Baryshev, A. (author), Zhang, W. (author), Jellema, W. (author), Hovenier, J.N. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Paveliev, D.G. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author), Klein, B. (author), Hesler, J.L. (author)
We demonstrate the phase locking of a 2.7 THz metal–metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x12) from a microwave synthesizer at ~15 GHz....
journal article 2009
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Ramakrishnan, G. (author), Chakkittakandy, R. (author), Planken, P.C.M. (author)
Generation of subpicosecond terahertz pulses is observed when graphite surfaces are illuminated with femtosecond near-infrared laser pulses. The nonlinear optical generation of THz pulses from graphite is unexpected since, in principle, the material possesses a centre of inversion symmetry. Experiments with highly oriented pyrolytic graphite...
journal article 2009
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Tenzer, R. (author), Novak, P. (author), Prutkin, I. (author), Ellmann, A. (author), Vajda, P. (author)
To reduce the numerical complexity of inverse solutions to large systems of discretised integral equations in gravimetric geoid/quasigeoid modelling, the surface domain of Green’s integrals is subdivided into the near-zone and far-zone integration sub-domains. The inversion is performed for the near zone using regional detailed gravity data. The...
journal article 2009
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Adam, A.J.L. (author), Planken, P.C.M. (author), Meloni, S. (author), Dik, J. (author)
We show terahertz reflection images of hidden paint layers in a painting on canvas and compare the results with X-ray Radiography and Infrared Reflectography. Our terahertz measurements show strong reflections from both the canvas/paint interface and from the raw umber/lead white interface, indicating sufficient refractive-index contrast. Our...
journal article 2009
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Seo, M.A. (author), Adam, A.J.L. (author), Kang, J.H. (author), Lee, J.W. (author), Ahn, K.J. (author), Park, Q.H. (author), Planken, P.C.M. (author), Kim, D.S. (author)
We performed terahertz near-field experiments on single rectangular holes with various lengths grown on an electro-optic crystal substrate with ?/100 resolution. We find that the near-field amplitude becomes proportionally larger as the rectangle becomes narrower, strongly suggesting that a constant energy passes through even for a very narrow...
journal article 2008
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Mauskopf, P. (author), Morozov, D. (author), Glowacka, D. (author), Goldie, D. (author), Withington, S. (author), Bruijn, M. (author), De Korte, P. (author), Hoevers, H. (author), Ridder, M. (author), Van der Kuur, J. (author), Gao, J.R. (author)
We describe the optimization of transition edge superconducting (TES) detectors for use in a far-infrared (FIR) Fourier transform spectrometer (FTS) mounted on a cryogenically cooled space-borne telescope (e.g. SPICA). The required noise equivalent power (NEP) of the detectors is approximately 10?19 W/ ?Hz in order to be lower than the photon...
conference paper 2008
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De Graauw, T. (author), Whyborn, N. (author), Helmich, F. (author), Dieleman, P. (author), Roelfsema, P. (author), Caux, E. (author), Phillips, T. (author), Stutzki, J. (author), Beintema, D. (author), Klapwijk, T. (author)
This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI), to be launched onboard of ESA's Herschel Space Observatory, by 2008. It includes the first results from the instrument level tests. The instrument is designed to be electronically tuneable over a wide and continuous frequency range in the Far Infrared, with velocity...
conference paper 2008
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Chakkittakandy, R. (author), Corver, J.A.W.M. (author), Planken, P.C.M. (author)
We describe a simple terahertz (THz) time domain spectrometer with a bandwidth extending up to 7.5 THz. We show that by keeping the generation and detection crystals close to each other a high signal-to-noise ratio (SNR) can be achieved without using lock-in detection and dry nitrogen flushing. The observed spectra show very good agreement with...
journal article 2008
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Hajenius, M. (author), Khosropanah, P. (author), Hovenier, J.N. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Barbieri, S. (author), Dhillon, S. (author), Filloux, P. (author), Sirtori, C. (author), Ritchie, D.A. (author), Beere, H.E. (author)
We characterize a heterodyne receiver based on a surface-plasmon waveguide quantum cascade laser (QCL) emitting at 2.84 THz as a local oscillator, and an NbN hot electron bolometer as a mixer. We find that the envelope of the far-field pattern of the QCL is diffraction-limited and superimposed onto interference fringes, which are similar to...
journal article 2008
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Docter, M.W. (author), Van den Berg, P.M. (author), Alkemade, P.F.A. (author), Kutchoukov, V.G. (author), Piciu, O.M. (author), Bossche, A. (author), Young, I.T. (author), Garini, Y. (author)
journal article 2007
Searched for: subject:"far"
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