“…PR-SHG measurements of monolayers at interfaces have previously been shown to enable discrimination between samples with similar nonlinear optical properties (Begue, Everly et al, 2009;Begue & Simpson, 2010;Begue, Moad et al, 2009). Further, polarization-dependent SHG microscopy has a rich history of enabling structural and orientational studies Amat-Roldan et al, 2010;Chang et al, 2011;Latour et al, 2012;Duboisset et al, 2012;Stoller et al, 2002;Mansfield et al, 2007;Nucciotti et al, 2009;Filippidis et al, 2009;Madden et al, 2011;Tuer et al, 2011;Brideau & Stys, 2012). PCA offers the advantages of simplicity, generality and the absence of required training when extracting the core features of high-dimensional data.…”