In physics, optically stimulated luminescence (OSL) is a method for measuring doses from ionizing radiation.The method makes use of electrons trapped between the valence and conduction bands in the crystalline structure of certain types of matter (such as quartz, feldspar, and aluminium oxide). The trapping sites are imperfections of the lattice — impurities or defects. The ionizing radiation produces electron-hole pairs: Electrons are in the conduction band and holes in the valence band.