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Optical Modelling using Gaussian Beam Modes for the Terahertz Band.

O'Sullivan, Créidhe and Murphy, John A. and Gradziel, Marcin L. and Lavelle, John and Peacocke, Tully and Trappe, Neil and Curran, Gareth S. and White, David R. and Withington, Stafford (2009) Optical Modelling using Gaussian Beam Modes for the Terahertz Band. Proceedings of SPIE: Terahertz Technology and Applications II, 7215. 72150P-1. ISSN 9780819474612

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Abstract

Special approaches unique to the waveband are required for the modelling of terahertz optical systems. Ray tracing is inadequate because in typical instruments the propagating beams are not very many wavelengths in diameter and a "quasi-optical" approach is required in which Fresnel diffraction effects can be efficiently and accurately simulated. Typically, it is also necessary to be able to simulate the coupling of quasi-optical beams to feed antenna structures to predict optical performance. In many systems the beams can be considered to be coherent and their propagation through a beam guide consisting of re-focussing elements can be efficiently modelled using modal analysis, especially useful for quick design purposes, beam control and optimisation. This modal approach has been extended to allow for aberrations and truncation particularly relevant in compact mirror based systems. At the same time physical optics, although computationally intensive, is also a useful tool when detailed analysis is required, particularly for providing crosspolarisation information and high accuracy far-field beam patterns from large reflecting antennas, for example. However, modal analysis in general is a very powerful tool, which enables one also to understand issues associated with throughput when partially coherent systems are being considered. This is important for the efficient optical modelling of large arrays systems now being developed for next generation astronomical instrumentation. In the presentation, we will discuss these issues and present examples from real instrumentation. We also summarise our continuing work on the development of computationally efficient modelling tools for fast quasi-optical design and analysis.

Item Type: Article
Additional Information: Copyright Notice: Créidhe M. O'Sullivan,John A. Murphy Marcin L. Gradziel, John Lavelle, Tully Peacocke, Neil Trappe, Gareth S. curran, David R. White and Stafford Withington, "Optical Modelling using Gaussian Beam Modes for the Terahertz Band," Terahertz Technology and Applications II, Kurt J. Linden, Laurence P. Sadwick, Créidhe M. O'Sullivan, Editors, Proc. SPIE 7215, 72150P-1 (2009). Copyright 2009 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. DOI: 10.1117/12.810807
Keywords: Terahertz; Quasi-Optical Modelling; Gaussian Beam Modes.
Subjects: Science & Engineering > Experimental Physics
Item ID: 1910
Identification Number: DOI: 10.1117/12.810807
Depositing User: Dr. Créidhe O'Sullivan
Date Deposited: 07 Apr 2010 17:31
Journal or Publication Title: Proceedings of SPIE: Terahertz Technology and Applications II
Publisher: Society of Photo-optical Instrumentation Engineers (SPIE)
Refereed: Yes
URI:

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