Index of refraction of germanium.

Measurements of the index of refraction of a sample of high-quality, single-crystal germanium using the minimum deviation refractometry method are presented for temperatures near 22°C and for wavelengths in the range 2 to 14 µm. The standard uncertainty for the measurements ranges from ${1.5} \times {{10}^{ - 5}}$1.5×10-5 to ${4.2} \times {{10}^{ - 5}}$4.2×10-5, generally increasing with wavelength. A Sellmeier formula fitting the data for this range is provided. Details of the custom system and procedures are presented, along with a detailed analysis of the uncertainty. These results are compared with previous measurements.