Femtosecond pump-probe microscopy generates virtual cross-sections in historic artwork

Area of Science:

• Art Conservation Science
• Optical Imaging
• Spectroscopy

Background:

• Studying the layering structure of paintings reveals artist techniques but typically requires destructive sampling.
• Existing noninvasive methods lack the resolution and molecular contrast needed for detailed stratigraphy analysis.

Purpose of the Study:

• To develop a 3D noninvasive imaging method for analyzing the stratigraphy of paintings.
• To enable the study of artist materials and working methods without damaging cultural heritage objects.

Main Methods:

• Adaptation of femtosecond pump-probe imaging, a technique previously used for biological tissues, to the analysis of paint layers.
• Combination of multispectral and multidelay pump-probe spectroscopy to achieve molecular and structural contrast.
• Application of the technique to mockup paintings and an intact 14th-century artwork.

Main Results:

• Demonstrated successful 3D noninvasive imaging of paint layers with molecular and structural contrast.
• Achieved virtual cross-sectioning capabilities, enabling pigment separation.
• Successfully imaged an intact 14th-century painting, 'The Crucifixion' by Puccio Capanna, non-destructively.

Conclusions:

• Femtosecond pump-probe imaging offers a powerful, noninvasive tool for analyzing the microscopic structure of paintings.
• This technique provides valuable insights into pigment composition and layering for art conservation and historical research.
• The method is effective even for pigments with broad, featureless absorption spectra.