Novel aspheric lenses for terahertz imaging

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dc.contributor.advisor Leonhardt, R en
dc.contributor.advisor Murdoch, Stuart en Lo, Yat Hei en 2020-07-08T04:50:12Z en 2020-07-08T04:50:12Z en 2009 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract We investigate the use of aberration-free aspheric lenses for terahertz imaging and spectroscopy. Replacing the traditionally used off-axis parabolic mirrors with lenses solves the problems of difficult alignment, susceptibility to aberrations, and limitation in terms of the numerical aperture. Carefully designing the lenses enables sub-wavelength imaging resolutions. Since the wavelength of terahertz radiation is much longer compared to optics, we employed geometric optics for designing the aspheric lenses to ensure zero aberration. We use ultra high molecular weight polyethylene as the Iens material, which has a refractive index similar to that of glass for optical wavelengths. The propagation of the beam, hence the focal spot size and the resulting spatial resolution, is determined using KirchhofTs scalar diffraction theory. Simulations show very promising imaging performances, in particular our novel symmetric-pass Iens design. Several experiments were carried out to verify the theoretical predictions. We show that the symmetric-pass Iens is able to achieve sub-wavelength resolution as Iow as 0.61λ. Moreover, in principle, our Iens designs presented in this thesis are applicable to other parts of the electromagnetic spectrum, depending on their application. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99189716414002091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. en
dc.rights Restricted Item. Full text is available to authenticated members of The University of Auckland only. en
dc.rights.uri en
dc.title Novel aspheric lenses for terahertz imaging en
dc.type Thesis en Physics en The University of Auckland en Doctoral en PhD en
dc.rights.holder Copyright: The author en

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