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Title: Reduction of effective terahertz focal spot size by means of nested concentric parabolic reflectors

An ongoing limitation of terahertz spectroscopy is that the technique is generally limited to the study of relatively large samples of order 4 mm across due to the generally large size of the focal beam spot. We present a nested concentric parabolic reflector design which can reduce the terahertz focal spot size. This parabolic reflector design takes advantage of the feature that reflected rays experience a relative time delay which is the same for all paths. The increase in effective optical path for reflected light is equivalent to the aperture diameter itself. We have shown that the light throughput of an aperture of 2 mm can be increased by a factor 15 as compared to a regular aperture of the same size at low frequencies. This technique can potentially be used to reduce the focal spot size in terahertz spectroscopy and enable the study of smaller samples.
Authors:
 [1] ;  [2] ; ; ;  [1]
  1. Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland, 21218 (United States)
  2. (Netherlands)
Publication Date:
OSTI Identifier:
22492374
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 9; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APERTURES; COMPARATIVE EVALUATIONS; DESIGN; FREQUENCY DEPENDENCE; OPTICAL REFLECTION; PARABOLIC REFLECTORS; POTENTIALS; SPECTROSCOPY; THZ RANGE; TIME DELAY; VISIBLE RADIATION