Dr. Darragh N. McCarthy Profile

Dr. Darragh N. McCarthy

Lecturer at National Univ of Ireland Maynooth

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Publications (7)

Proceedings Article | 24 February 2017 Paper

Radiation patterns of multimode feed-horn-coupled bolometers for FAR-IR space applications

Eimante Kalinauskaite, J. Anthony Murphy, Ian McAuley, Neal Trappe, Darragh McCarthy, Colm Bracken, Stephen Doherty, Marcin Gradziel, Créidhe O'Sullivan, Daniel Wilson, Tully Peacocke, Bruno Maffei, Jean-Michel Lamarre, Peter A. Ade, Giorgio Savini

Proceedings Volume 10103, 101030N (2017) https://doi.org/10.1117/12.2249869

KEYWORDS: Bolometers, Sensors, Waveguides, Extremely high frequency, Terahertz radiation, Beam controllers, Black bodies, Thin films, Computer simulations, Waveguide modes, Electronic filtering, Scattering, Matrices, Optical simulations, Thermal modeling, Free space

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Proceedings Article | 19 July 2016 Paper

Optical design and verification of a 4mm receiver for the 20m telescope at Onsala Space Observatory

George Walker, Eimante Kalinauskaite, Darragh McCarthy, Neil Trappe, Anthony Murphy, Leif Helldner, Miroslav Pantaleev, Jonas Flygare

Proceedings Volume 9914, 99142V (2016) https://doi.org/10.1117/12.2232576

KEYWORDS: Optical design, Receivers, Space telescopes, Telescopes, Space observatories, Optical design, Receivers, Space telescopes, Telescopes, Space observatories, Mirrors, Optical instrument design, Gaussian beams, Reflectors, Beam propagation method

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Proceedings Article | 19 July 2016 Paper

Modeling multimode feed-horn coupled bolometers for millimeter-wave and terahertz astronomical instrumentation

Eimante Kalinauskaite, Anthony Murphy, Ian McAuley, Neil Trappe, Colm Bracken, Darragh McCarthy, Stephen Doherty, Marcin Gradziel, Creidhe O'Sullivan, Bruno Maffei, Jean-Michel Lamarre, Peter A. Ade, Giorgio Savini

Proceedings Volume 9914, 99142R (2016) https://doi.org/10.1117/12.2231444

KEYWORDS: Sensors, Bolometers, Waveguides, Scattering, Antennas, Matrices, Waveguide modes, Systems modeling, Resistance, Absorption

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Proceedings Article | 19 July 2016 Paper

Optical characterisation and analysis of multi-mode pixels for use in future far infrared telescopes

Darragh McCarthy, Neil Trappe, J. Anthony Murphy, Stephen Doherty, Marcin Gradziel, Créidhe O'Sullivan, Michael Audley, Gert de Lange, Maarten van der Vorst

Proceedings Volume 9914, 991413 (2016) https://doi.org/10.1117/12.2231710

KEYWORDS: Far infrared, Far infrared, Sensors, Free space, Waveguides, Waveguide modes, Matrices, Wave propagation, Scattering, Modeling, Systems modeling

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In this paper we present the development and verification of feed horn simulation code based on the mode- matching technique to simulate the electromagnetic performance of waveguide based structures of rectangular cross-section. This code is required to model multi-mode pyramidal horns which may be required for future far infrared (far IR) space missions where wavelengths in the range of 30 to 200 µm will be analysed. Multi-mode pyramidal horns can be used effectively to couple radiation to sensitive superconducting devices like Kinetic Inductance Detectors (KIDs) or Transition Edge Sensor (TES) detectors. These detectors could be placed in integrating cavities (to further increase the efficiency) with an absorbing layer used to couple to the radiation. The developed code is capable of modelling each of these elements, and so will allow full optical characterisation of such pixels and allow an optical efficiency to be calculated effectively. As the signals being measured at these short wavelengths are at an extremely low level, the throughput of the system must be maximised and so multi-mode systems are proposed. To this end, the focal planes of future far IR missions may consist of an array of multi-mode rectangular feed horns feeding an array of, for example, TES devices contained in individual integrating cavities. Such TES arrays have been fabricated by SRON Groningen and are currently undergoing comprehensive optical, electrical and thermal verification. In order to fully understand and validate the optical performance of the receiver system, it is necessary to develop comprehensive and robust optical models in parallel. We outline the development and verification of this optical modelling software by means of applying it to a representative multi-mode system operating at 150 GHz in order to obtain sufficiently short execution times so as to comprehensively test the code. SAFARI (SPICA FAR infrared Instrument) is a far infrared imaging grating spectrometer, to be proposed as an ESA M5 mission. It is planned for this mission to be launched on board the proposed SPICA (SPace Infrared telescope for Cosmology and Astrophysics) mission, in collaboration with JAXA. SAFARI is planned to operate in the 1.5-10 THz band, focussing on the formation and evolution of galaxies, stars and planetary systems. The pixel that drove the development of the techniques presented in this paper is typical of one option that could be implemented in the SAFARI focal plane, and so the ability to accurately understand and characterise such pixels is critical in the design phase of the next generation of far IR telescopes.

Proceedings Article | 23 July 2014 Paper

Efficient algorithms for optimising the optical performance of profiled smooth walled horns for future CMB and Far-IR missions

Darragh McCarthy, Neil Trappe, J. Anthony Murphy, Créidhe O'Sullivan, Marcin Gradziel, Stephen Doherty, Colm Bracken, Niall Tynan, Arturo Polegre, Peter Huggard

Proceedings Volume 9153, 915316 (2014) https://doi.org/10.1117/12.2056336

KEYWORDS: Phase measurement, Waveguides, Antennas, Scattering, Polarization, Sensors, Microwave radiation, Manufacturing, Bolometers, Throat

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Astronomical observations in the far-infrared are critical for investigation of cosmic microwave background (CMB) radiation and the formation and evolution of planets, stars and galaxies. In the case of space telescope receivers, a strong heritage exists for corrugated horn antenna feeds to couple the far-infrared signals to the detectors mounted in a waveguide or cavity structure. Such antenna feeds have been utilized, for example, in the Planck satellite in both single-mode channels for the observation of the CMB and the multi-mode channels optimized for the detection of foreground sources. Looking to the demands of the future space missions, it is clear that the development of new technology solutions for the optimization and simplification of horn antenna structures will be required for large arrays. Horn antennas will continue to offer excellent control of beam and polarization properties for CMB polarisation experiments satisfying stringent requirements on low sidelobe levels, symmetry, and low cross polarization in large arrays. Similarly for far infrared systems, multi-mode horn and waveguide cavity structures are proposed to enhance optical coupling of weak signals for cavity coupled bolometers. In this paper we present a computationally efficient approach for modelling and optimising horn character-istics. We investigate smooth-walled horns that have an equivalent optical performance to that of corrugated horns traditionally used for CMB measurements. We discuss the horn optimisation process and the algorithms available to maximise performance of a merit parameter such as low cross polarisation or high Gaussicity. A single moded horn resulting from this design process has been constructed and experimentally verified in the W band. The results of the measurement campaign are presented in this paper and compared to the simulated results, showing a high level of agreement in co and cross polarisation radiation patterns, with low levels of integrated cross polar power. For future Far IR receivers using waveguide bounded bolometers and absorbers, an optimisation of the waveg-uide structures and absorber location within the integrating cavity is critical to maximise coupling performance particularly for multimoded systems. We outline the benefit of using multi-moded horns in focal plane arrays and illustrate the increased optical sensitivity associated with a many-moded approach, which may be optimized for coupling to particular incident beams.

Proceedings Article | 27 March 2013 Paper

Efficient horn antennas for next-generation terahertz and millimeter-wave space telescopes

Darragh McCarthy, Neil Trappe, Anthony Murphy, Colm Bracken, Stephen Doherty, Marcin Gradziel, Créidhe O'Sullivan

Proceedings Volume 8624, 862413 (2013) https://doi.org/10.1117/12.2001268

KEYWORDS: Scattering, Matrices, Waveguides, Antennas, Polarization, Space telescopes, Genetic algorithms, Wave propagation, Microwave radiation, Signal detection

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Proceedings Article | 24 February 2011 Paper

Applications of holography in the millimeter-wave and terahertz region

I. McAuley, J. Murphy, N. Trappe, R. Mahon, D. McCarthy, P. McLaughlin

Proceedings Volume 7938, 79380H (2011) https://doi.org/10.1117/12.873821

KEYWORDS: Antennas, Holograms, Holography, Waveguides, Phase measurement, Digital holography, Dielectrics, Sensors, Image restoration, Wavefronts

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Showing 5 of 7 publications

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