Rack, A.; Garcia-Moreno, F.; Helfen, L.; Mukherjee, M.; Jiménez, C.; Rack, T.; Cloetens, P.; Banhart, J.: Hierarchical radioscopy using polychromatic and partially coherent hard synchrotron radiation. Applied Optics 52 (2013), p. 8122-8127
10.1364/AO.52.008122

Abstract:
Pushing synchrotron x-ray radiography to increasingly higher image-acquisition rates (currently up to 100,000 fps) while maintaining spatial resolutions in the micrometer range implies drastically reduced fields of view. As a consequence, either imaging a small subregion of the sample with high spatial resolution or only the complete specimen with moderate resolution is applicable.We introduce a concept to overcome this limitation by making use of a semi-transparent x-ray detector positioned close to the investigated sample. The hard x-rays that pass through the sample either create an image on the first detector or keep on propagating until they are captured by a second x-ray detector located further downstream. In this way, a process can be imaged simultaneously in a hierarchical manner within a single exposure and a projection of the complete object with moderate resolution as well as a subregion with high resolution are obtained. As a proof-of-concept experiment, image sequences of an evolving liquidmetal foam are shown, employing frame rates of 1000 images∕s (1.2 μm pixel size) and 15;000 images∕s (18.1 μm pixel size) for the first and second detector, respectively. © 2013 Optical Society of America OCIS codes: (000.2170) Equipment and techniques; (110.6915) Time imaging; (320.3980) Microsecond phenomena; (340.6720) Synchrotron radiation; (340.7440) X-ray imaging.