The name is absent

37

Figure 4.4 : Compressed sensing reconstructions of (a) the image amplitude and (b)
the phase, using 400 (complex) measurements. Here, the object is a rectangular hole
in an opaque screen, covered with a (transparent) plastic plate. The plate covering
the upper half of the hole is thicker than the lower half. The reconstructed phase
image exhibits this contrast much better than the amplitude image.

sparsity of the object in the reconstruction basis and on the system noise [59]. In
general, this decay is fast until the number of measurements reaches the sparsity level
of the object. The experimental result is consistent with this trend.

4.4 Imaging results: Complex images

There have been very few implementations of CS systems capable of acquiring and
reconstructing complex image data. Since pulsed THz systems are well-known for pro-
viding spectroscopic phase information, this experiment demonstrates the capability
in our single-pixel system, using CS algorithms specifically designed to reconstruct
complex images [57]. The object to be imaged consists of a simple rectangular hole,
half of which is covered by a transparent plastic plate. For each random pattern,
both the magnitude and phase of the THz radiation at a single frequency (again, 100
GHz) are determined. CS reconstruction with 400 measurements using the SPGLl
algorithm (see [57]) yields the image amplitude and phase shown in Figure 4.4. While

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