Laser heating in thermoluminescence dosimetry

Thermoluminescence (TL) glow curves have been obtained from γ‐irradiated commercial dosimetry materials (LiF:Mg, Ti; CaSO4:Mn; CaSO4:Dy; CaF2:Dy; Li2B4O7) with a novel laser heating technique. It utilizes short (10–1000 ms) pulses from a CO2 laser of 1–8 W power focused to about 1‐mm diam spot sizes onto thin (<100 μm) layers of powder precipitated on microscope cover slides. In some cases these powder layers were spray coated with a thin film of conventional high temperature polymers. These acted both as a binder to stabilize the powder as well as to enhance the heat transfer from the laser beam to those TL materials which have a small absorption coefficient for 10.6 μm photons (e.g., LiF and CaF2). Heating rates in excess of 104 K s−1 have been observed without noticeable decrease in the TL emission efficiency. Laser heating is, thus, shown to be a promising technique to increase the signal‐to‐noise ratio of TL emission signals. As a result, true microdosimetry in the mR range could be demonstrated with...