A luminescence imaging system based on a CCD camera

Stimulated luminescence arising from naturally occurring minerals is likely to be spatially heterogeneous. Standard luminescence detection systems are unable to resolve this variability. Several research groups have attempted to use imaging photon detectors, or image intensifiers linked to photographic systems, in order to obtain spatially resolved data. However, the former option is extremely expensive and it is difficult to obtain quantitative data from the latter. This paper describes the use of a CCD camera for imaging both thermoluminescence and optically stimulated luminescence. The system described here has a maximum spatial resolution of 17 μm, though this may be varied under software control to alter the signal-to-noise ratio. The camera has been mounted on a Risø automated TL/OSL reader, and both the reader and the CCD are under computer control. In the near u.v and blue part of the spectrum, the CCD system is less sensitive than the standard bi-alkali photocathode photomultipliers that are commonly used. However, the CCD has a peak performance between 500 and 900 nm, and is more sensitive than the photomultiplier tube over this range.