Fig. 4: Calibration of carbon layer thickness via azimuthal dark-band angles in DL-pACGs.

Calibration curve showing the relationship between carbon layer thickness and the azimuthal angles corresponding to the dark bands. The red line with square markers represents the azimuthal angles predicted by simulations, while the circular data points with error bars indicate the experimentally measured values. Note that the plotted data are based on the modeled film thicknesses obtained from ellipsometry. The shaded regions indicate the expected angular spread of the reflection dip due to the finite illumination cone, as estimated using Eq. (3). The orange region corresponds to an incident angle range of 0–5°, and the pink region corresponds to 5–10°.