Potential of luminescence imaging for screening sensitive and well-bleached samples for rock surface luminescence dating.

Rock surface luminescence dating is being increasingly applied to constrain the chronologies of geological and archaeological deposits. Here we investigate the potential of the newly developed Risø Imager, a mobile system for measurements in the field, for screening samples with desirable luminescence characteristics. We show by analysing 8 different rock samples, that the Imagers sensitivity is about 50 times lower that than the more commonly used Risø TL-OSL Reader. However, the measurement sensitivity can be improved using longer acquisition times for non-destructive infrared photoluminescence. The imager provides a far superior resolution and precision in the luminescence-depth profiles compared to the Reader, with measurement times as small as few minutes. However, based on the examination of luminescence values at zero depth, we speculate that cross-talk from the poorly-bleached, regions below the focal plane of the Imager may be a source of contamination in the luminescence depth profiles, an aspect which requires future investigations. • Sensitivity comparison of the Risø TL-OSL Reader and a portable Risø Imager. • Difference between the two systems similar across 8 different rock types. • A clear advantage of the Imager is its unprecedented spatial resolution (<100 μm). • Surface bleaching better in the Reader due to potential cross talk in Imager. • Trivial to obtain luminescence-depth profiles from the Imager in a few minutes. [ABSTRACT FROM AUTHOR]