Assessments of refractivity in a Fabry-Perot (FP) cavity by refractometry often encompass a step in which the penetration depth of the light into the mirrors is estimated to correct for the fraction of the cavity length into which no gas can penetrate. However, as it is currently carried out, this procedure is not always coherently performed. Here, we discuss a common pitfall that can be a reason for this and provide a recipe on how to perform FP-cavity-based refractometry without any influence of mirror penetration depth.
Errata: C. Forssén, I. Silander, J. Zakrisson, M. Zelan, and O. Axner , "Retraction: “Fabry–Perot-cavity-based refractometry without influence of mirror penetration depth” [J. Vac. Sci. Technol. B 39, 065001 (2021)]", Journal of Vacuum Science & Technology B 40, 037001 (2022) https://doi.org/10.1116/6.0001829