Improved spectral imaging microscopy for cultural heritage through oblique illumination

Lindsay Oakley, Stephanie Zaleski, Billie Males, Oliver Cossairt, Marc Walton*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

This work presents the development of a flexible microscopic chemical imaging platform for cultural heritage that utilizes wavelength-tunable oblique illumination from a point source to obtain per-pixel reflectance spectra in the VIS–NIR range. The microscope light source can be adjusted on two axes allowing for a hemisphere of possible illumination directions. The synthesis of multiple illumination angles allows for the calculation of surface normal vectors, similar to phase gradients, and axial optical sectioning. The extraction of spectral reflectance images with high spatial resolutions from these data is demonstrated through the analysis of a replica cross-section, created from known painting reference materials, as well as a sample extracted from a painting by Pablo Picasso entitled La Miséreuse accroupie (1902). These case studies show the rich microscale molecular information that may be obtained using this microscope and how the instrument overcomes challenges for spectral analysis commonly encountered on works of art with complex matrices composed of both inorganic minerals and organic lakes.

Original languageEnglish (US)
Article number27
JournalHeritage Science
Volume8
Issue number1
DOIs
StatePublished - Dec 1 2020

Keywords

  • Dictionary learning
  • Micro analysis
  • Oblique illumination
  • Optical sectioning
  • Picasso
  • Spectral imaging microscopy
  • Surface shape

ASJC Scopus subject areas

  • Conservation
  • Archaeology
  • Archaeology

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