Interpolation of Refractive Index Data

Abstract

A comparison of the interpolation of index of refraction data for Czochralski sapphire, cyclohexane, and polystyrene dissolved in cyclohexane using a three-term Sellmeier equation, the Lorentz-Lorenz equation with six terms, third and fifth order polynomials, and a cubic-spline technique indicates that the cubic spline method is extremely valuable for simple interpolation. Not only were the magnitudes of the rms and average absolute residuals the smallest, but the fits showed no systematic errors.