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6.1 Introduction
Second harmonic generation (SHG) imaging microscopy has great potential for visualization of disease
states where there is change in collagen structure. is is because SHG, as a second-order nonlinear
optical process, requires a noncentrosymmetric environment, and tissue alterations modify the overall
symmetry of the collagen architecture. Specically, SHG is an exquisitely sensitive probe of the brillar
structure in tissues as it directly visualizes the supramolecular assembly, over the size scale of collagen
brils to bers, that is, from ~50 nm to a few microns. While there are approximately 20 isoforms of
collagen, t ...