title: A novel facility for ageing materials with narrow-band ultraviolet radiation exposure.
abstract: A facility for exploring wavelength dependencies in ultraviolet (UV) radiation induced degradation in materials has been designed and constructed. The device is essentially a spectrograph separating light from a lamp to spectrally resolved UV radiation. It is based on a 1 kW xenon lamp and a flat-field concave holographic grating 10 cm in diameter. Radiation at the wavelength range 250-500 nm is dispersed onto the sample plane of 1.5 cm in height and 21 cm in width. The optical performance of the device has been characterized by radiometric measurements. Using the facility, test samples prepared of regular newspaper have been irradiated from 1 to 8 h. Color changes on the different locations of the aged samples have been quantified by color measurements. Yellowness indices computed from the color measurements demonstrate the capability of the facility in revealing wavelength dependencies of the material property changes in reasonable time frames.
authors.affiliation: Aalto University, School of Science and Technology, Metrology Research Institute, Aalto, Finland.
authors.forename: Petri
authors.initials: P
authors.lastname: Kärhä
authors.forename: Anu
authors.initials: A
authors.lastname: Heikkilä
authors.forename: Kimmo
authors.initials: K
authors.lastname: Ruokolainen
authors.forename: Merja
authors.initials: M
authors.lastname: Kaunismaa