Finn, Timothy J. and Trappe, Neil and Murphy, J.Anthony and Withington, S. (2008) The Gaussian beam mode analysis of off-axis aberrations in long wavelength optical systems. Infrared Physics & Technology, 51 (4). pp. 351-359. ISSN 1350-4495

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Abstract

An issue of major concern in the design of long wavelength systems is optical aberration or distortion, which can be particularly severe in off-axis systems. Aberrations occur in both lenses and mirrors and in this paper we present a novel method capable of modelling off-axis mirror configurations. Aberrations degrade fundamental receiver coupling coefficients such as aperture efficiency while increasing spillover power losses. For single pixel instruments this will lead to much longer integration times and the possibility of stray light. For imaging arrays the aberrations cause a departure from perfect point imaging by increasing coupling to array detectors located at angles further off the bore sight of the telescope. This paper verifies a matrix-based scheme using Gaussian beam mode analysis (GBMA) for predicting aberrations from off-axis mirrors. The applied technique was originally described in (S. Withington, A. Murphy, G. Isaak, Representation of mirrors in beam waveguides as inclined phase transforming surfaces, Infrared Phys. Tech. 36(3) (1995) 723–734. [1]) and in this paper we exploit the theory and validate the approach with a series of examples using off-axis conic sections. We present the predictions for both a fundamental Gaussian and a scalar horn field illuminating various off-axis mirror configurations including different angles of incidence. A commercially available physical optics (PO) software package, GRASP8™, is used to validate the accuracy of these scalar GBMA predictions.

Item Type:	Article
Additional Information:	The authors would like to acknowledge financial support from the Irish Research Council of Science, Engineering and Technology (IRCSET) and from PRODEX through Enterprise Ireland that enabled this work to be completed.
Keywords:	Aberrations; Long wavelength; Quasioptics (QO); Gaussian beam modes (GBM); Physical optics;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	9833
Identification Number:	https://doi.org/10.1016/j.infrared.2007.10.003
Depositing User:	Dr. Neil Trappe
Date Deposited:	27 Aug 2018 14:16
Journal or Publication Title:	Infrared Physics & Technology
Publisher:	Elsevier
Refereed:	Yes
Funders:	Irish Research Council for Science Engineering and Technology (IRCSET), Enterprise Ireland (EI)
URI:	https://www.sciencedirect.com/
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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