The Rigaku Journal Vol. 23 / 2006, 40–47

One of the latest developments in X-Ray Fluorescence Analysis (XRF) is 3D micro-XRF by means of two confocally aligned X-ray optics. Fig. 1 sketches the principle of this type of experimental setup. The foci of two X-ray optics, one in the excitation channel and the other in the detection channel, overlap and define a probing volume. This is typically demonstrated by scanning through the probing volume with thin foils. The count rate is recorded, while the foil is moved stepwise through the probing volume. Fig. 2 depicts a count rate profile obtained with such a depth-scan. The resolution achieved up to now is around 20 mm. Over the past three years, a number of applications carried out at various synchrotron radiation facilities demonstrated the usefulness of the new 3D micro-XRF method [2, 3, 4, 8]. In particular, the method is a unique tool if cross sections of the sample cannot be prepared. The investigation of art objects (paintings) has been its first and most frequent application [2, 3, 7, 9]. Three-dimensional imaging has been carried out for samples from geology by Vincze et al. They investigated a liquid inclusion in a diamond [8, 1]. Biological specimens were investigated by Janssens et al. In a demonstration experiment, the trace element distribution in a small marine lobster was recorded [4]. In contrast to the experimental part, which can be considered as developed to a large extent (at least with respect to synchrotron radiaTHE RIGAKU JOURNAL VOL. 23 / 2006, 40–47