Interspecimen Comparison of the Refractive Index of Fused Silica*,†

TLDR

The study measured the refractive index of optical‑quality fused silica across 60 wavelengths at 20 °C, quantified specimen‑to‑specimen variation among 12 samples, and compared the results to prior NBS data. A dispersion equation n²–1=0.6961663/λ²–0.0684043²+0.4079426/λ²–0.1162414²+0.8974794/λ²–9.896161² with an absolute residual of 10.5×10⁻⁶ was obtained, and the material’s dispersive properties and thermal coefficient of index were graphically presented.

Abstract

The index of refraction of optical quality fused silica (SiO2) was determined for 60 wavelengths from 0.21 to 3.71 μ at 20°C. The dispersion equation n2-1=0.6961663λ2λ2-(0.0684043)2+0.4079426λ2λ2-(0.1162414)2+0.8974794λ2λ2-(9.896161)2.where λ is expressed in microns was found to yield an absolute residual of 10.5×10−6. The variation in index between 12 specimens was determined. Dispersive properties of the material and thermal coefficient of index are graphically presented. A comparison with previous NBS index data is discussed.