High‐Resolution Near‐Field Imaging and Far‐Field Sensing Using a Transmissive Programmable Metasurface

Abstract

Abstract Electromagnetic (EM) inverse problem for detecting and sensing unknowns has attracted tremendous attention. Here, without using bulk lens, a method is proposed to realize both near‐field imaging and far‐field detection with high resolutions using a novel transmissive programmable metasurface. The presented low‐profile metasurface has good features of continuous and full transmission phase coverage to realize strong wave‐control capabilities. For imaging and detecting an interested area, the EM‐wave focusing points or beams of illumination can be spatially shifted with short distance in different directions, respectively. On the basis, the fields at the spatially shifted focusing points can be synthesized to obtain improved point spread function for scanning, which will achieve higher sensing resolution than the wave illumination of focusing scanning only. By employing the new transmissive programmable metasurface, the metallic objects in the near field are successfully imaged and two corner reflectors in the far field are detected in experiments, both with high resolutions. The measured and simulated results have good agreements, thus verifying the validity and efficiency of the proposed method and transmissive programmable metasurface.