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- 2016 (2) (entfernen)
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- Non-destructive testing (2) (entfernen)
Light damage to selected organic materials in display cases: A study of different light sources
(2016)
The protection of works of art and cultural assets against light-induced aging is vital when planning exhibitions. Newly developed lighting systems render the selection of suitable light sources more difficult, not least in the context of energy–economical systems. This study accordingly examines different lighting systems (fluorescent tubes, halogen lamps, low-voltage metal halide lamps, and LED lamps) in terms of the damage potential they hold for the materials concerned. The changes in color were evaluated using the CIEDE2000 color-difference formula. This study focuses on selected organic materials and shows that changes in color already occur after only a brief exposure time. The color changes induced by the fluorescent tubes were consistently more intense than those induced by the other light sources. The results obtained with the remaining lamps show that the color changes depend more on the material under investigation than on the source used. The changes determined after a relatively short exposure period (five months) vividly demonstrate that exposing sensitive materials to light for longer terms (as is the case during a permanent exhibition) is most definitely a non-viable option.
Comparison of concepts for a point-shaped energy density detector after flash lamp excitation
(2016)
The paper describes investigations and Research work in order to develop a simple sensor for the quantification of spectral broadband energy Dissipation of flash lamps at any point in space. Such Flash lamps are often used as energy source during active thermography testing (TT). Here, the temperature transient of the sensor surface has to be recorded by the infrared camera that is already present. During the following data evaluation, the energy input into the investigated specimen can be determined. Two opposite concepts were considered: thermal thick and thermal thin probes. The direct comparison shows advantages for thermal thick probes based on the physics of thermal balance processes.