Seibersdorf Laboratories have recently conducted research into the potential for damaging of artworks exposed to a laser scanner FARO Focus3D X was investigated. The issue to asses was if the absorption of laser light in the superficial layers of paint and varnish on canvas can lead to an increase in temperature that could deteriorate the quality of the artwork.
Computer modelling was used to calculate the highest rise in temperature achievable in a worst-case exposure scenario. The question of this study was if it is possible to rule out the possibility for thermally-induced damage of paintings when using the laser scanner FARO Focus3D X. Other potential effects such as photochemical interactions or accelerated ageing provoked by extended exposures over the course of days or more go beyond the scope of the present study.
Given the unknown physical properties of the irradiated artworks, conservative values along with a worst-case exposure scenario (such as the scanner remains on one path and the scanner head does not turn in the horizontal plane, but also regarding choice of optical and thermal properties) were considered. In view of this, the rise in temperature at the surface of the painting was calculated to be less than 2 degrees. Considering that the scanner head also turns in horizontal direction, one spot on the painting would be exposed for less than 10 seconds at the lowest angular speed (0,004 revolutions per minute), during which the calculated rise in temperature was less than 1,3 °C.
Figure 1. Calculated time-temperature history at the surface of the painting exposed to the laser scanner FARO Focus3D X (distance 1 m, minimum rotation frequency)
Such increase is less than, or as a worst case of the order of magnitude of temperature variations that can be observed indoors purely from ambient air temperature, even in a museum where the ambient temperature is controlled. Thus it can be excluded that paintings undergo temperature-induced deterioration after exposure to the laser scanner FARO Focus3D X.
Moreover, it can be ruled out that the melting point of the components of dried oil paint and hardened superficial layers (e.g. varnish) can be reached in the chosen exposure scenario, thus ruling out the possibility of a phase change. Similarly, it can be assumed that the change in thermal and optical properties is negligible over the range of 2°C around ambient temperature.