Refractive Properties of Barium Fluoride*

Abstract

Refractive properties of barium fluoride are discussed. The refractive index, n, was determined at 25°C for 46 measured wavelengths from 0.2652 μ in the ultraviolet to 10.346 in the infrared. The dispersion equation n2−1=0.643356λ2λ2−(0.057789)2+0.506762λ2λ2−(0.10968)2+3.8261λ2λ2−(46.3864)2,where λ is expressed in microns was found to fit the measured values with an average absolute residual of 1.91×10−5. A tentative average thermal coefficient of index dn/dt for the measured spectral range is −12×10−6/°C Dispersive quantities which indicate the expected relative dispersion, chromatic aberration, and the effect of index on resolution are graphically presented. A review of transmittance data from the literature is also presented.