Confocal X-ray fluorescence spectrometer for in-situ analyses of paintings

•Confocal XRF spectrometer for in-situ measurements of painting was constructed.•Preparation of a sample plate of historical paint layers was described.•Movable collimating optics enables us to change quickly the confocal volume.

This paper describes the properties of the newly constructed device for confocal X-ray fluorescence analysis that was tested with a sample plate consisting of 19 combinations of two single pigment layers. The preparation of this experimental wooden board with layered systems was based on knowledge of the panel painting techniques of Bohemian collections from the National Gallery in Prague dating back to the 14th and 15th centuries. The design of the confocal setup allows its transport and the in-situ measurement of paintings in depositories or even in exhibition areas. The advantages of our confocal setup with movable collimating optics are also described.