Modeling of Light-Induced Changes in Reflectance Spectra: A Predictive Tool for the Effect of an Arbitrary Spectral Irradiance

ABSTRACT

Optical radiation is capable of altering the spectral reflectance of layers of colorants. Light damage is of particular importance in respect to unique historical objects in exhibitions. The major parameter governing this process is the spectral irradiance applied to the surface. As this may vary significantly for different light sources, an experimental investigation of the damage potential of the numerous illuminants available is a cumbersome task. In this work a numerical algorithm for the prediction of modifications of the spectral reflectance of colorants subject to a given arbitrary spectral irradiance over a given time is presented. It uses the temporal evolution of the spectral reflectance of the dye or pigment at issue when irradiated by a set of narrowband light sources as input data. The predicted reflectance spectra and the resulting color changes are compared to those measured for samples irradiated with common polychromatic light sources. The concept described in this work aims at the implementation of a standardized procedure and database for the prediction of radiative damage for a comprehensive range of pigments and dyes.

KEYWORDS:

• Historic colorants
• predictive model
• spectral reflectance
• light-induced damage
• pigments
• dyes
• LED light sources
• narrow band light sources

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Beate Villmann is a Lecturer in the Physics section at Leipzig University of Applied Sciences. Her research focuses on the combined use of experimental and numerical methods for the identification of material properties.

Gregor Peltri is a Lecturer on mathematics at Leipzig University of Applied Sciences. His main expertise is in the mathematical modelling of data sets.

Christian Weickhardt is a Professor in the Physics section at Leipzig University of Applied Sciences. His main research interests include optical spectroscopy and the development of laser based analytical techniques.

ORCID

Beate Villmann http://orcid.org/0000-0003-2819-7055

Additional information

Funding

This work was supported by a grant from the German Federal Government Commissioner for Culture and the Media on the basis of a resolution passed by the German Bundestag and the Cultural Foundation of the German Federal States.