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We discuss several tradeoffs presented in the design of active imaging systems for the 100 to 1000 GHz frequency range, describe how we have addressed them in the design of a scanning, 95 GHz, bolometer-based imager for concealed weapons detection that is nearing completion, and describe how the system architecture can be modified to scale the operating(More)
Terahertz imaging makes it possible to acquire images of objects concealed underneath clothing by measuring the radiometric temperatures of different objects on a human subject. The goal of this work is to automatically detect and segment concealed objects in broadband 0.1-1 THz images. Due to the inherent physical properties of passive terahertz imaging(More)
This paper describes a calibrated broadband emitter for the millimeter-wave through terahertz frequency regime, called the aqueous blackbody calibration source. Due to its extremely high absorption, liquid water is chosen as the emitter on the basis of reciprocity. The water is constrained to a specific shape (an optical trap geometry) in an expanded(More)
This article describes the theory and design of an ultra-low noise electronic readout circuit for use with room temperature video-rate terahertz imaging arrays. First, the noise characteristics of various imaging detectors, including low resistance bolometers and high resistance diodes are discussed. Theoretical approaches to white and 1/f noise mitigation(More)
We describe a broadband terahertz camera based on a modular 64-element linear array of superconducting hot-spot microbolometers. Unlike many superconducting sensor arrays, the readout for this array is performed entirely by uncooled electronics; no SQUIDs or cryogenic HEMTs are employed. The operating principles for the microbolometer and the readout scheme(More)
—We describe the results of bistatic scattering measurements covering 325-650 GHz on a series of well-characterized random rough test surfaces. These have implications for active THz imagers that use coherent sources for illumination. The mean scattered intensity is compared to theoretical predictions based on an integral equation method, and the(More)
[1] We use a fifty-year record of wintertime radiosonde observations at the South Pole to estimate the precipitable water vapor column (PWV) over the entire period. Humidity data from older radiosondes is of limited reliability; however, we think an estimation of PWV is possible using temperature data because the wintertime lower troposphere is very close(More)
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