Radiation-Induced Changes of Dimensions, Index of Refraction, and Dispersion of Lithium Fluoride

Deuteron, electron, gamma ray, and x-ray irradiated specimens were examined by a photoelastic method and by interferometric methods. In addition to the increase in physical dimensions, there were found an increase in refractive index and an increase in dispersion, and these were measured. The results agree with the classical dispersion formulas if it is assumed that the effects are caused by a change in the refractivity of the base material due to the introduction of vacancies and holes and a change in the refractivity due to the $F$ centers and the 450 centers, the size of the vacancies being about that of the absent ions and the oscillator strength of the $F$ centers being near unity.