Metamaterial Apertures for Computational Imaging

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Science  18 Jan 2013:
Vol. 339, Issue 6117, pp. 310-313
DOI: 10.1126/science.1230054

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  1. Fig. 1

    Comparison of (A) conventional and (B and C) compressive imaging schemes. A conventional imager uses a lens to form measurement modes that effectively map all parts of an object to a detector/image plane. Each mode contributes highly specific and localized information, and all modes can be captured simultaneously with a pixel array or other detector. Within single-pixel schemes, many types of modes can be used to form the image, with measurements being captured sequentially. In the example shown in (B), a random mask and two lenses are used to project incoherent modes that sample the entire scene. The microwave metamaterial imager reported here (C) makes use of a planar waveguide that feeds a holographic array of ELCs, removing the need for lenses. The waveguide acts as a coherent single-pixel device, with the array of ELCs serving to produce the illuminating complex spatial modes.

  2. Fig. 2

    Simulated far-field profiles for the metamaterial aperture at two frequencies: 18.5 GHz (A) and 21.8 GHz (B). Resonant metamaterial apertures (C) can create mode distributions that vary with frequency. (D) Measured magnitude of the measurement matrix, H, as a function of angle and frequency.

  3. Fig. 3

    (A) Reconstructions of four different static scenes (differentiated by color), consisting of two (black, green, and blue) or three (red) 10-cm scattering objects. The solid "+" symbols show the actual location of objects, and the pixels show the reconstructed image. Pixel size reflects the maximum instrument resolution. The image has been cropped from the full field of view of ±70°. (B) Photograph of a single scene corresponding to the black markers in (A).

  4. Fig. 4

    (Left) Image of a single moving object at 10-Hz frequency. Each voxel is sized to match the spatio-temporal resolution of the metamaterial aperture, and the amplitude of the reconstructed scattering density is mapped to the transparency of each voxel. Voxels are also color-coded in time, from blue to red. (Right) Data projections in two dimensions.

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