The Ellipsometry window computes the ellipsometric angles Ψ and Δ for the active design — the amplitude-ratio and phase-shift quantities that an ellipsometer reports. Use it to predict what your instrument should see for a given coating, so you can compare a simulated curve against a measured one or plan a measurement.

The angles come from the complex reflectance ratio between p- and s-polarized light:

ρ = r_p / r_s = tan(Ψ) · exp(i Δ)

You can sweep either wavelength at a fixed angle, or angle of incidence at a fixed wavelength.

Settings

Mode — sweep over wavelength (spectral) or over angle of incidence (angular).

Side — evaluate the front coating or the back coating. Ellipsometry models a single coherent reflection off one face, so each side is treated independently.

Wavelength range and step (spectral mode) — the span and sampling interval of the sweep, in nm.

AOI (spectral mode) — the fixed angle of incidence, in degrees. The default of 65° is a common ellipsometer angle near the Brewster region of typical substrates.

Wavelength (angular mode) — the fixed wavelength for an angle sweep.

AOI range and step (angular mode) — the span and sampling interval of the angle sweep, in degrees.

How to read it

Ψ is plotted on the left axis (0–90°) and Δ on the right axis (0–360°). Ψ encodes the ratio of the p and s reflection amplitudes, and Δ their phase difference. In an angle sweep, the substrate’s Brewster angle shows up as a sharp step in Δ, which makes a useful calibration check.

The data table lists Ψ and Δ against the swept variable for export. This window is a forward calculation: to recover layer thicknesses from a measured Ψ and Δ, use Refinement with targets set on those quantities.

References

• H. G. Tompkins & E. A. Irene, Handbook of Ellipsometry (William Andrew, 2005).
• H. A. Macleod, Thin-Film Optical Filters, 5th ed., p. 553 (Eq. 16.2).