A Millimeter-Wave Photometric Camera for Long-Range Imaging Through Optical Obscurants Using Kinetic Inductance Detectors

TL;DR

This paper introduces SKIPR, a 150 GHz polarization-sensitive camera using kinetic inductance detectors, designed for long-range imaging through optical obscurants, with detailed design, characterization, and in situ performance results.

Contribution

The paper presents the design, construction, and characterization of SKIPR, a novel millimeter-wave camera employing a large array of kinetic inductance detectors for passive long-range imaging.

Findings

SKIPR achieves diffraction-limited imaging performance.

Detector noise is dominated by ambient photon arrivals.

Focal plane array has a 92% detector yield.

Abstract

Passive imaging through optical obscurants is a promising application for mm-wave sensing. We have thus developed the Superconducting Kinetic Inductance Passive Radiometer (SKIPR), a 150 GHz polarization-sensitive photometric camera optimized for terrestrial imaging using a focal plane array with 3,840 kinetic inductance detectors (KIDs). We present a full description of the instrument design, with a particular emphasis on the cryogenic system based on a Gifford-McMahon cryocooler with a two-stage Adiabatic Demagnetization Refrigerator and a dedicated 1.59 m crossed Dragone telescope with an altitude/azimuth mount. We include a detailed lab-based characterization of the KIDs, which results in a determination of their superconducting resonator parameters and optical properties. We also present in situ measurements from the telescope, including point-spread functions and noise characterization. In sum, we find that SKIPR performs as expected, providing diffraction-limited imaging with detector noise performance set by the random arrivals of photons from the ambient background. There is minimal variation in detector characteristics over the full SKIPR focal plane array, and the overall detector yield is 92 per cent.