Depth-Resolved Multilayer Pigment Identification in Paintings: Combined Use of Laser-Induced Breakdown Spectroscopy (LIBS) and Optical Coherence Tomography (OCT)

Abstract

A detailed feasibility study on the combined use of laser-induced breakdown spectroscopy with optical coherence tomography (LIBS/OCT), aiming at a realistic depth-resolved elemental analysis of multilayer stratigraphies in paintings, is presented. Merging a high spectral resolution LIBS system with a high spatial resolution spectral OCT instrument significantly enhances the quality and accuracy of stratigraphic analysis. First, OCT mapping is employed prior to LIBS analysis in order to assist the selection of specific areas of interest on the painting surface to be examined in detail. Then, intertwined with LIBS, the OCT instrument is used as a precise profilometer for the online determination of the depth of the ablation crater formed by individual laser pulses during LIBS depth-profile analysis. This approach is novel and enables (i) the precise in-depth scaling of elemental concentration profiles, and (ii) the recognition of layer boundaries by estimating the corresponding differences in material ablation rate. Additionally, the latter is supported, within the transparency of the object, by analysis of the OCT cross-sectional views. The potential of this method is illustrated by presenting results on the detailed analysis of the structure of an historic painting on canvas performed to aid planned restoration of the artwork.

A critical review of recent progress in analytical laser-induced breakdown spectroscopy

“…In a feasibility study, this combination was suggested for use in depthresolved multi-layer pigment identification in paintings [95]. An OCT scan can provide high-resolution 3D images of the layers in the paintings, and can assist LIBS in depth-resolved elemental-composition studies by accurately measuring ablation-crater depths and ablation rates.…”

“…Novel tandem instruments, for example Raman-LIBS, have also found well-suited applications in this field, as already alluded to in the instrumental section of this review. A recent example of this trend is the state-of-the-art combined instrument incorporating optical-coherence tomography and LIBS (OCT-LIBS) [95], which was specifically constructed to aid multilayer pigment identification in paintings. This instrument enables the fast, high-resolution, nondestructive visualization of stratigraphy in paintings and makes depth-profiling substantially more precise.…”

Non‐Invasive Periodontal Probing Through Fourier‐Domain Optical Coherence Tomography

“…E arly diagnosis in health care is desirable and necessary since it implies a better patient prognosis. Imaging methods are widely used in diagnostic medicine, as reviewed by Dhawan et al 1 Among the diversity of imaging modalities, optical coherence tomography (OCT), first introduced by Huang et al, 2 is now commercially available and considered the most innovative imaging technique used in ophthalmology; 3 it is also used in several other clinical applications such as dermatology, 4,5 gastroenterology, 6 cardiology, 7 gynecology, 8 oncology, 9 dentistry, 10,11 and non-medical applications, for instance, painting 12 and evaluation of materials' porosity. 13 In dentistry, OCT studies in hard and soft tissues have been performed since 1998, 10 and they have been proposed to be an effective tool to evaluate early caries and caries-related issues [14][15][16][17][18][19] and oral cancer.…”

Obtaining Cross-Sections of Paint Layers in Cultural Artifacts Using Femtosecond Pulsed Lasers

“…The potential to eliminate the need for polishing can thus avoid problems during the polishing process, such as cross-contamination between paint layers, or with sand particles [18]. We also note that under a more stringent experimental geometry, it may be possible to employ laser induced breakdown spectroscopy (LIBS) while making the cut, in order to gain more information about the sample [19]. …”