Samples to Determine the Resolution of Neutron Radiography and Tomography

Abstract

Knowing the resolution and effective pixel size of an imaging system is essential for dimensional and quantitative measurements. A collection of test devices was developed for neutron imaging that can be used to quantify pixel and voxel size, resolution of the imaging system, and beam divergence. The first set of devices is intended for measurements with radiographs using test patterns or an absorbing edge. For tomography, Al vials were filled with Ti spheres of increasing dimensions in each vial. Ti was chosen since it provides sufficient contrast while the transmission is still guaranteed. The first resolution criterion was to determine from which vial that the spheres can be uniquely identified as spheres. More complex analysis would involve measuring the volume of the spheres or even to compute the edge spread function analogous to the method with the knife-edge for radiographs. For the edge analysis, a larger Ti sphere was considered. Using a sphere for the edge spread function analysis allowed for determination of the resolution in any direction. Images acquired using the different test items are included and methods to perform the analysis required to quantify the resolution from the images are proposed.