The dependence of optical absorption and thermoluminescence of LiF crystals on F band bleaching time at different temperatures is used to study the mechanism of “restored” thermoluminescence as applied in thermoluminescence dosimetry. F centers turn out to act as electron sources for refilling of traps. Simultaneously, additional Z2 centers responsible for the TL main peak five are created by the presence of F centers during F band bleaching. The results confirm the close relationship between the 3.3 eV absorption band and the TL pre‐peaks.