A Redetermination of Some Optical Properties of Calcium Fluoride

This paper gives refractive-index values at 24°C for a synthetic and a natural prism of calcium fluoride. Measurements were made by the minimum-deviation method at 46 calibrated wavelengths from 0.23 μ in the ultraviolet to 9.7 μ in the infrared. The indices of the synthetic prism were fitted to a three-term Sellmeier dispersion formula of the form: n2 − 1 = ∑Ajλ2/(λ2 − λj2). Dispersive quantities were computed which estimate the expected relative dispersion, chromatic aberration, and resolution of CaF2 as a function of wavelength. Values of dn/dt are also given. The results of this work are compared with previously reported data.