Two-color arrays for sub-terahertz/infrared imaging

Abstract

Here is considered the conception of two-color broadband detectors based on narrow-gap mercury-cadmium-telluride (MCT) thin layers. Two-colour un-cooled and cooled to 78 K MCT thin layers with antennas were considered both as sub-terahertz (sub-THz) direct detection bolometers, and 3 to 10 μm infrared (IR) photoconductors. The design and dimensions of THz detector antennas were calculated for reasonable detector sensitivity within the 150–300-GHz frequency range. Implications of printed antennas usage in FPA on thick substrate are investigated. Patterns of detector element with planar antenna in the focal plane of the focusing system are studied. Diffraction limited optical system was designed and manufactured with four identical plano-convex aspherical lenses. THz images of objects hidden behind the gypsum plasterboard or foam plastic packing are presented for the radiation frequencies 70, 140, and 275 GHz.