Precision Spectral Goniometer

To determine the refractive index and dispersion with high accuracy, SCHOTT uses the automated spectral goniometer “URIS” (Ultraviolet to infrared Refractive Index measurement System).

This method enables the refractive index of optical glass to be measured with an accuracy of up to ± 4 · 10–6 and dispersion up to ± 2 · 10–6 in an extended spectral range from 185 nm to 2325 nm. Using a tempered sample chamber, it is possible to determine the temperature coefficient of refraction with an accuracy of ± 5 · 10–7 · K-1 between - 100 °C and + 140 °C. This takes place using the method of minimal deviation in the autocollimation position.

On request, precision test certificates can be provided for refraction indexes in an extended spectral range with the constants of the Sellmeier formula. Measurements for the precision test certificates are performed in air at a temperature of 22 °C and at a pressure of 1013.3 hPa. On request, the measurement temperature can be carried out to constant values of between 18 °C and 28 °C in nitrogen.