Some applications of one-dimensional coded apertures

The dimensional coded apertures have been investigated for use in imaging long, narrow objects such as reactor fuel pins. Since coded apertures work better for small, point-like objects, while pinhole apertures work better for large extended objects, a hybrid aperture combining these properties seems attractive for imaging fuel pins. The one-dimensional aperture behaves like a coded aperture in the direction for which the object is small, while it acts like a pinhole in the direction for which the object is extended. A one-dimensional Fresnel zone plate has been investigated, and an iterative, nonlinear algorithm has been developed for removing the background produced by extra-core values in the point spread function. The algorithm is shown to have a decidedly nonlinear effect on the effective system transfer function. Uniformly redundant sequences have also been investigated as possible aperture codes. They can produce filled apertures and result in a decoded image with a uniform background level that can be easily removed by subtraction.