Accuracy of Refractive Index Spectroscopy by Broadband Interferometry

TL;DR

This paper analyzes the uncertainties in measuring refractive and group indices using broadband interferometry, identifying key factors affecting accuracy and quantifying total measurement uncertainty across a broad spectral range.

Contribution

It provides a detailed uncertainty analysis for spectrally resolved white light interferometry in refractive index measurements, highlighting dominant error sources.

Findings

Uncertainty contributions vary with measurement parameters

Total uncertainty can be quantitatively estimated by combining individual errors

Measurement accuracy is affected mainly by specific parameters over the spectral range

Abstract

Uncertainties of refractive and group index in dispersion measurement by spectrally resolved white light interferometry are deeply analyzed. First, the contribution to uncertainty of the different parameters affecting both indices is identified. Afterwards, results are presented for a 1.5 mm thick fused silica sample over a broad spectral range, from 400 to 1000 nm, and the effects that mostly deteriorate the measurement accuracy are established. Finally, the different contributions are quadratically combined to determine the total uncertainty of the two indices.