Abstract
We demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements of spatially-diverse field patterns, diffraction-limited images of human-sized subjects are reconstructed. The system is driven by a single microwave source swept over a band of frequencies (17.5–26.5 GHz) and switched between a collection of transmit and receive metasurface panels. High fidelity image reconstruction requires a precise model for each field pattern generated by the aperture, as well as the manner in which the field scatters from objects in the scene. This constraint makes scaling of computational imaging systems inherently challenging for electrically large, coherent apertures. To meet the demanding requirements, we introduce computational methods and calibration approaches that enable rapid and accurate imaging performance.
Highlights
Archetypical approaches to mmW imaging have relied on either (a) sampling an aperture with a dense array of sources for beam forming, as in active electronically scanned antennas (AESAs)[9], or (b) mechanically scanning a transceiver over the aperture, as in synthetic aperture radar (SAR) systems[10,11]
From microwave to x-ray, and even in the acoustic regime, demonstrations of computational imaging (CI) approaches are numerous in the literature[13,14,15,16,17,18,19]
Scene information is multiplexed across many non-orthogonal measurements, with the image reconstructed using more general CI algorithms
Summary
Archetypical approaches to mmW imaging have relied on either (a) sampling an aperture with a dense array of sources for beam forming, as in active electronically scanned antennas (AESAs)[9], or (b) mechanically scanning a transceiver over the aperture, as in synthetic aperture radar (SAR) systems[10,11]. The former approach yields fast acquisition times but with expensive hardware, while the latter approach has inherently slow acquisition time. Such apertures can acquire scene information using only a frequency sweep from a single source, without moving parts[23]
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