Developments in quasi-optical design for THz

Creidhe O'Sullivan; J. Anthony Murphy; Gary Cahill; Marcin Lukasz Gradziel; Neil Trappe; David White; Vladimir Yurchenko; Stafford Withington; Willem Jellema

doi:10.1117/12.551660

8 October 2004 Developments in quasi-optical design for THz

Creidhe O'Sullivan, J. Anthony Murphy, Gary Cahill, Marcin Lukasz Gradziel, Neil Trappe, David White, Vladimir Yurchenko, Stafford Withington, Willem Jellema

Author Affiliations +

Proceedings Volume 5498, Millimeter and Submillimeter Detectors for Astronomy II; (2004) https://doi.org/10.1117/12.551660
Event: SPIE Astronomical Telescopes + Instrumentation, 2004, Glasgow, United Kingdom

Abstract

Optical design in the terahertz (THz) waveband suffers from a lack of dedicated software tools for modelling the range of electromagnetic and quasi-optical propagation conditions encountered in typical systems. Optical engineers are forced to use packages written for very different wavelength systems and there is often a lack of confidence in the results because of possible inappropriate underlying physical models. In this paper we describe the analytical techniques and dedicated CAD software tools (MODAL) that we are developing for long-wavelength design and analysis in the THz waveband. Our basic approach to modelling long-wavelength propagation is the application of modal analysis appropriate to the problem under investigation. We have extended this to include the efficient description of common off-axis (tilted) components such as simple curved reflectors. In earlier research we have investigated the conditions under which approximate methods (ray tracing, paraxial modes) can provide extremely efficient and accurate solutions and situations where a more rigorous approach is required. As a rigorous model of electromagnetic wave propagation, physical optics can be used to characterize complete systems to high accuracy. However, the straightforward approach is computationally intensive and, therefore, not suitable for the initial design or preliminary analysis of large multi-element optical systems. In order to improve the computational efficiency of the usual PO approach we have developed fast physical optics software, initially for the analysis of the ESA PLANCK system. The MODAL code is modular and multi-platform, and different propagation models can be used within the same framework. Distributed parallel computing enables significant reduction of the time needed to perform the calculations. We present the new software and analyses of the QuaD and Herschel (HIFI) telescope systems.

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Creidhe O'Sullivan, J. Anthony Murphy, Gary Cahill, Marcin Lukasz Gradziel, Neil Trappe, David White, Vladimir Yurchenko, Stafford Withington, and Willem Jellema "Developments in quasi-optical design for THz", Proc. SPIE 5498, Millimeter and Submillimeter Detectors for Astronomy II, (8 October 2004); https://doi.org/10.1117/12.551660

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