New light on OSL

We have tested recently released green and blue light emitting diodes (LEDs) for the optical stimulation of quartz, with a view to using these in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry. We compare results obtained with blue LEDs with those obtained using broad-band blue/green light filtered from a halogen lamp. We describe two practical blue LED OSL configurations and conclude that a small number of blue LEDs provide the same stimulation efficiency for quartz as can be obtained from filtered halogen lamps and other commonly used sources. From the direct comparison of OSL decay curves produced by the two light sources, and by examination of the dependence of blue LED OSL on preheat temperature, we conclude that there is no evidence that the blue LED light stimulates deep traps in a different manner from broad-band halogen light. Preliminary intercomparisons, using 34 quartz samples taken from both heated and unheated materials, between equivalent doses obtained using blue LEDs and using broad-band blue/green light from a halogen lamp show that, on average, the two data sets are indistinguishable (blue/halogen = 0.98 +/- 0.02). We conclude that blue LEDs offer a practical alternative to existing stimulation sources. They have the significant advantage that the output can be controlled electronically; thus the power can be readily controlled by software. (C) 1999 Elsevier Science Ltd. All rights reserved.