OSLDs

Optically stimulated luminescent dosimeters (OSLDs) are passive devices used to measure ionizing radiation exposure. They rely on materials such as aluminum oxide doped with carbon (Al2O3:C) that trap charge carriers when irradiated. After exposure, stimulation with a light source releases the stored energy as luminescent light, with the emitted intensity proportional to the absorbed dose.

The operating principle involves charging centers created by radiation within the dosimeter’s material. When stimulated by light (often blue LED or laser), the trapped electrons are released, producing photons detected by a photomultiplier or photodiode. The resulting signal is read out by an OSL reader and converted into an absorbed dose using calibration standards. OSLDs can typically be read multiple times and may require light bleaching to reset between uses.

Construction and use vary by application. OSLDs come as small chips or discs embedded in badge holders, wand readers, or integrated into dosimetry systems. They are used for occupational radiation monitoring in medical imaging, nuclear power, and industrial radiography, as well as in clinical dosimetry and some dental applications. Their relatively small size enables convenient placement on the body or near a region of interest.

Advantages of OSLDs include high sensitivity, a wide usable dose range, reusability after bleaching, and good stability of stored signals. They provide rapid readouts and have well-characterized energy responses. Limitations include the need for specialized readout equipment and calibration, potential fading or signal loss if not stored properly, and dose measurement accuracy dependent on proper bleaching, lighting conditions, and energy dependence corrections.

See also: dosimetry, optically stimulated luminescence, dosimeter.