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 rout ine optically stimulated luminescence (OSL) dating and retrospective dosime try. We compare results obtained with blue LEDs with those obtained using b road-band blue/green light filtered from a halogen lamp. We describe two pr actical blue LED OSL configurations and conclude that a small number of blu e LEDs provide the same stimulation efficiency for quartz as can be obtaine d from filtered halogen lamps and other commonly used sources. From the dir ect comparison of OSL decay curves produced by the two light sources, and b y 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 inte rcomparisons, using 34 quartz samples taken from both heated and unheated m aterials, between equivalent doses obtained using blue LEDs and using broad -band blue/green light from a halogen lamp show that, on average, the two d ata sets are indistinguishable (blue/halogen = 0.98 +/- 0.02). We conclude that blue LEDs offer a practical alternative to existing stimulation source s. They have the significant advantage that the output can be controlled el ectronically; thus the power can be readily controlled by software. (C) 199 9 Elsevier Science Ltd. All rights reserved.