Videoholography

Videoholography, also known as electronic speckle pattern interferometry (ESPI), is based on the coherence of laser light and on interference patterns. The interference of such light beams leads to constructive or destructive changes in the intensity of the light. The resulting interference patterns can uncover micro-deformations in the entire surface of the object of study, without causing any damage. In a modification of the ESPI-method, a light source with very short coherence length is used to selectively measure the characteristics of individual, superimposed layers of paint or lacquer. In combination with climate chambers, this method allows predictions of the extent of deformation that the consolidated lacquer layers will exhibit in fluctuating temperature or humidity levels.

Between 1999 and 2003, the team of Dr. Gerd Gülker, Study Group for Applied Optics, Faculty of Physics at the Carl-von-Ossietzky-University Oldenburg, carried out and analysed systematic ESPI measurements both on consolidated original fragments and on samples of the consolidants. The results yielded valuable information on the influence of individual components on the stability of the consolidant films.

Dr. Gerd Gülker (Institute for Physics, University Oldenburg)
Dr. Arne Kraft (ATLAS-ELEKTRONIK GmbH)
Dipl. Physiker Akram El Jarad (ibea GmbH)