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 degrees C and for wavelengths in the range 2 to 14 mu m. The standard uncertainty for the measurements ranges from 1.5 x 10(-5) to 4.2 x 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.