Large scanning areas
The lab-designed instrument allows for raster scanning areas from a couple of square centimeters up to scanning windows of 80 x 80 cm2, large enough to scan a full painting in a single run.
About the Technique
Scanning macro X-ray fluorescence (MA-XRF) is an imaging technique that allows the non-destructive elemental mapping of large, mostly flat, surfaces. It is used for the investigation of inorganic materials used in works of art, such as pigments, lakes, or inks.
The mapping is achieved by a raster scanning of the surface with a focused X-ray beam and analyzing the emitted fluorescence radiation. X-rays do not stop at the surface of the artworks and therefore, both top and bottom layers will contribute to the analyzed signal and thus to the elemental distribution images. Consequently, this technique is highly valuable for the investigation of artists' palette and technique, previous conservation treatments, or hidden sub-surfaces such as pentimenti (modifications of the composition done by the artists themselves), or complete re-use of a canvas.
Technical Details of the In-House Instrument
Tunable scanning parameters
Currently equipped with a removable polycapillary focusing optics, the MA-XRF can image small details down to about 150 um in size. Nonetheless, the pixel size can be increased to scan larger areas without fine details.
Portability
The MA-XRF from the Center for Scientific Studies in the Arts was designed as a transportable instrument. Therefore, it can be boxed and shipped in order to perform analysis in situ.
Adaptive sampling
Adaptive sampling addresses the issue of slow acquisition speed and x-ray dosage on a painting by moving away from traditional raster scanning and towards a subsampling scanning path that updates as data are collected. This represents a gain of time while achieving high-quality XRF mapping.
Applications
Related Projects
Related Publications
Publication(s)
Pouyet, E., N. Barbi, H. Chopp, O. Healy, A. Katsaggelos, S. Moak, R. Mott, M. Vermeulen, M. Walton. 2020. “Development of a highly mobile and versatile large MA-XRF scanner for in-situ analyses of painted work of arts.” X-Ray Spectrometry
Dai, Q., H. Chopp, E. Pouyet, O. Cossairt, M. Walton, A. Katsaggelos. 2019. "Adaptive Image Sampling Using Deep Learning and its Applications on X-Ray Fluorescence Image Reconstruction." IEEE Transactions on Multimedia
Presentation(s)
Pouyet, E., MA-XRF at the Northwestern University/Art Institute of Chicago Center for Scientific Studies in the Arts. MA-XRF scanning in Conservation, Art and Archeology, Catania, October 15-16, 2019