Tomographical Imaging Using Uniformly Redundant Arrays

Recent work in coded aperture imaging has shown that the uniformly redundant array (URA) can image distant planar radioactive sources with no artifacts. This paper investigates the performance of two URA apertures when used in a close-up tomographic imaging system. It is shown that a URA based on m sequences is superior to one based on quadratic residues. The m-sequence array not only produces less noticeable defocus artifacts in tomographic imaging but is also more resilient to some described detrimental effects of close-up imaging. It is shown that, in spite of these close-up effects, the URA system retains tomographic depth resolution even as the source is moved close to the detector. The URAs based on m sequences provide better images than those obtained using random arrays. This compliments previous studies that have shown random arrays to have better tomographical properties than Fresnel zone plates and nonredundant arrays.