In [1] the analyzer azimuth, $A_2=90°-A_1$, for detecting the second angle of incidence ${\phi }_{C2}$(> the Brewster angle ${\phi }_B$) at which $R_s=2R_p$ (using a null-seeking polarizer-surface-analyzer (PSA) ellipsometer with a $\phi -2\phi$ goniometer) is incorrect. For incident linearly polarized light at azimuth $P=45°$, the second analyzer azimuth at null should be $A_2=-A_1=-35.264°$, because the $p$ and $s$ components of the electric vector of reflected light are 180° out of phase at ${\phi }_{C1}<{\phi }_B$ but are in phase at ${\phi }_{C2}>{\phi }_B$, in accordance with the Nebraska–Muller conventions [2].

Careful analysis shows that the precision of locating ${\phi }_{C2}$ is better than that of locating ${\phi }_B$. However, the opposite is true with respect to ${\phi }_{C1}$. The second sentence after Eq. (19) in [1] should be amended accordingly.