Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published June 2010 | Published
Journal Article Open

Confocal Ellipsoidal Reflector System for a Mechanically Scanned Active Terahertz Imager

Abstract

We present the design of a reflector system that can rapidly scan and refocus a terahertz beam for high-resolution standoff imaging applications. The proposed optical system utilizes a confocal Gregorian geometry with a small mechanical rotating mirror and an axial displacement of the feed. For operation at submillimeter wavelengths and standoff ranges of many meters, the imaging targets are electrically very close to the antenna aperture. Therefore the main reflector surface must be an ellipse, instead of a parabola, in order to achieve the best imaging performance. Here we demonstrate how a simple design equivalence can be used to generalize the design of a Gregorian reflector system based on a paraboloidal main reflector to one with an ellipsoidal main reflector. The system parameters are determined by minimizing the optical path length error, and the results are validated with numerical simulations from the commercial antenna software package GRASP. The system is able to scan the beam over 0.5 m in cross-range at a 25 m standoff range with less than 1% increase of the half-power beam-width.

Additional Information

© 2010 IEEE. Manuscript received July 01, 2009; revised November 16, 2009; accepted December 25, 2009. Date of publication March 29, 2010; date of current version June 03, 2010. This work was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This work was supported under a contract to the California Institute of Technology, Division of Biology, by the Naval Explosive Ordnance Disposal Technology Division, with funding provided by the DoD Physical Security Equipment Action Group (PSEAG).

Attached Files

Published - Llombart2010p10545Ieee_T_Antenn_Propag.pdf

Files

Llombart2010p10545Ieee_T_Antenn_Propag.pdf
Files (1.3 MB)
Name Size Download all
md5:e411853e070f191d88d8b5b34ba201f7
1.3 MB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 20, 2023