A new technique produces X-ray images in colour quickly and efficiently using a specially-structured device called a Fresnel zone plate (FZP). The technique could have applications in nuclear medicine and radiology, as well in non-destructive industrial testing and materials analysis.
X-rays are frequently used to determine the chemical composition of materials thanks to the characteristic “fingerprint” of fluorescence that different substances emit when exposed to X-ray light. At present, however, this imaging technique requires focussing the X-rays and scanning the whole sample. Given the difficulty of focusing an X-ray beam down to small areas, especially with typical laboratory X-ray sources, this is a challenging task, making images time-consuming and expensive to produce.
The new method, developed by Jakob Soltau and colleagues at the Institute for X-ray Physics at the University of Göttingen, Germany, allows an image from a large sample area to be obtained with just a single exposure, while doing away with the need for focusing and scanning. Their approach uses an X-ray colour camera and a gold-plated FZP placed between the object being imaged and the detector. FZPs have a structure of opaque and transparent zones that are often used to focus X-rays, but in this experiment, the researchers were interested in something else: the shadow the FZP casts on the detector when the sample is illuminated.
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