Effect of 60Co γ irradiation on the optical properties and microhardness of LiF, LiF:OH - , and LiF:OH - :Mg2 + crystals Alekseev, P. D. ; Gering, G. I. ; Panova, T. K. Abstract Publication: Optics and Spectroscopy Pub Date: November 1992 Bibcode: 1992OptSp..73..538A