ISO 23131-2:2026

This document specifies the process for determining the optical or dielectric constants by means of ellipsometric measurements and their analysis based on the bulk material model.
If the assumptions of the bulk material model are strictly met, it is possible to determine the optical constants (refractive index n and extinction coefficient k) or the dielectric constants (real part ε1 and imaginary part ε2) of the material directly. Alternatively, optical (<n> and <k>) or dielectric (<ε1> and <ε2>) pseudo constants are determined, which depend on the measurement angle of incidence φ. The degree of consistency of the pseudo constants in the relevant spectral range, determined from measurements at different angles of incidence, represents a necessary prerequisite for the validity or quality of the bulk material model.