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Proceedings Paper

Aspherical lenses for terahertz spectroscopy
Author(s): Yat Hei Lo; Rainer Leonhardt
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Paper Abstract

Using Terahertz (THz) beams with fairly large beam diameters (~20 mm) and short focal length lenses (25 mm) to obtain a high spatial resolution makes it essential to use aspherical lenses. As High Density Polyethylene (HDPE) lenses can be machined to any arbitrary shape with high surface quality, there are several free parameters that can be varied when designing a lens that has no spherical aberrations. We present several different lens designs and evaluate their performances in terms of losses and focal spot sizes. Geometrical optics is used to design the lenses but the Kirchhoff Scalar Diffraction theory is employed to evaluate the beam sizes in the focal planes. The performances of the lenses were also analyzed experimentally, where their focal spot sizes were measured and compared with our models. Results show that spatial resolutions of less than the THz wavelengths (0.3 mm for 1 THz) are achievable with our imaging system.

Paper Details

Date Published: 8 January 2008
PDF: 10 pages
Proc. SPIE 6801, Photonics: Design, Technology, and Packaging III, 68011R (8 January 2008); doi: 10.1117/12.768901
Show Author Affiliations
Yat Hei Lo, Univ. of Auckland (New Zealand)
Rainer Leonhardt, Univ. of Auckland (New Zealand)

Published in SPIE Proceedings Vol. 6801:
Photonics: Design, Technology, and Packaging III
Wieslaw Z. Krolikowski; Costas M. Soukoulis; Ping Koy Lam; Timothy J. Davis; Shanhui Fan; Yuri S. Kivshar, Editor(s)

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