Ellipsometry inversion

Fit refractive index n(λ), extinction k(λ) and thickness d from spectroscopic ellipsometry Ψ, Δ data. Single or multi-angle.

Cauchy + Urbach dispersion model fit by bounded gradient-descent. Multi-angle data resolves the (n, d) ambiguity of single-angle measurements. Built-in synthetic demo dataset; CSV upload supported.