High-energy X-ray micro-lamino­graphy to visualize microstructures in dense planar objects

High-energy X-ray micro-lamino­graphy has been developed to observe inner- and near-surface structures in dense planar objects that are not suitable for observation by X-ray micro-tomography. A multilayer-monochromator-based high-intensity X-ray beam with energy of 110 keV was used for high-energy and high-resolution lamino­graphic observations. As a demonstration of high-energy X-ray micro-lamino­graphy for observing dense planar objects, a compressed fossil cockroach on a planar matrix surface was analyzed with effective pixel sizes of 12.4 µm and 4.22 µm for wide field of view and high-resolution observations, respectively. In this analysis, the near-surface structure was clearly observed without undesired X-ray refraction-based artifacts from outside of the region of interest, a problem typical in tomographic observations. Another demonstration visualized fossil inclusions in a planar matrix. Micro-scale features of a gastropod shell and micro-fossil inclusions in the surrounding matrix were clearly visualized. When observing local structures in the dense planar object with X-ray micro-lamino­graphy, the penetrating path length in the surrounding matrix can be shortened. This is a significant advantage of X-ray micro-lamino­graphy where desired signals generated at the region of interest including optimal X-ray refraction effectively contribute to image formation without being disturbed by undesired interactions in the thick and dense surrounding matrix. Therefore, X-ray micro-lamino­graphy allows recognition of the local fine structures and slight difference in the image contrast of planar objects undetectable in a tomographic observation.