a Schematic of the GHOSTEAM system. The spintronic THz emitter array (STEA) is excited by two-DMD-encoded fs laser pulses and generates spatially coded THz pulses. An object “CAEP” was placed in the near-field region (z ≪ λ). The illuminating THz pulse was collected and sent to a single-pixel detector. b Schematic of the STEA, consisting of a W(2 nm)/Fe(2 nm)/Pt(2 nm) trilayer heterostructure and working in the binary emission state with polarization perpendicular to applied magnetic field B. Spatiotemporal THz waveform along the horizontal (c) and vertical (d) directions. The wavefront is indicated by white dotted lines, and time t = 0 is indicated by black dotted lines. |ΔtH| and |Δtv| are the temporal delays in the horizontal and vertical directions, respectively. e Schematic of the detection for ghost imaging, and measured signal Y (which is the difference between the positive mask value and negative mask value, Y = |Yp| − |Yn|, in the case of Hadamard multiplexing) from the single-pixel detector for an object “CAEP” illuminated by a sequence of prearranged structured THz waves. f Estimated SNRs as a function of pixel number N under the condition of a pump fluence of 2.88 mJ cm−2, FOV1 = 834 μm × 834 μm. The red marker with a value of 10.92 ± 0.97 is the experimental result (see the main text below and Supplementary section 4 for details).
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