Analysis and Design of Dual Band THz Imager Based on Incoherent Detectors

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Abstract

This work focuses on designing and evaluating the performance of a dual-band passive imager for security applications at sub-mm wave regime. The bolometer based kinetic inductive detectors are used as incoherent detectors on the focal plane array of this imaging system. In order to realize a dual-band system, two absorber sets are designed to operate at separate frequency bands and reject power at the other band. The frequency selectivity of the design is introduced by using the absorber based frequency selective surfaces as a layer on top of the bolometer based detectors. Using the provided spectral analysis tools, the total performance of the detector coupled optics is evaluated. This evaluation is performed in terms of the optical efficiency, the angular response of the imager to a point source, the angular resolution and the noise equivalent temperature difference of the imager. The mentioned parameters are obtained for a generic parabolic reflector based imager coupled to a detector located at the center of the FPA. Moreover, using GRASP computational software and the provided analysis method, the performance of the specific optics used in the CONSORTIS imaging system for the detector at the center of the FPA and also at the edge are approximated.

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