Spectroscopic - Ellipsometry

Because it measures a rather than absolute intensity, SE is highly resistant to light source fluctuations and does not typically require a reference sample, making it exceptionally accurate. How It Works: The Experimental Setup

A second rotating polarizer (and sometimes a compensator) that detects the change in the light's state. Spectroscopic Ellipsometry

Can resolve the individual properties of many stacked layers simultaneously. Because it measures a rather than absolute intensity,