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Title: Infrared measurements and simulations of metal meshes in a focused beam

Infrared transmittance measurements of quasioptical filters are often restricted to a focused beam due to the optical design of the spectrometer. In contrast, numerical simulations assume an incident plane wave, which makes it difficult to compare theory with experimental data. We compare transmittance measurements with numerical simulations of square arrays of circular holes in 3-μm thick Cu sheets at angles of incidence from 0° to 20° for both s and p polarizations. These simple structures allow detailed tests of our electromagnetic simulation methods and show excellent agreement between theory and measurement. Measurements in a focused beam are accurately simulated by combining plane wave calculations over a range of angles that correspond to the focal ratio of the incident beam. Similar screens have been used as components of narrow bandpass filters for far-infrared astronomy, but these results show that the transmittance variations with angle of incidence and polarization limit their use to collimated beams at near normal incidence. The simulations are accurate enough to eliminate a costly trial-and-error approach to the design of more complex and useful quasioptical infrared filters and to predict their in-band performance and out-of-band blocking in focused beams.
Authors:
 [1] ; ;  [2]
  1. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States)
  2. Electrical Engineering Department, New Jersey Institute of Technology, Electronic Imaging Center, Newark, New Jersey 07102 (United States)
Publication Date:
OSTI Identifier:
22278115
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; COPPER; FAR INFRARED RADIATION; INCIDENCE ANGLE; OPACITY; OPTICAL FILTERS; PHOTON BEAMS; POLARIZATION; WAVE PROPAGATION