Multiphoton microscopy and SHG

Nonlinear microscopy has undergone impressive growth in the last 20 years, making it one of the most used optical tools in biological and biomedical imaging of cells and tissues. The main features offered by this microscopy technique consist in providing an intrinsic optical sectioning, an increased penetration depth in optically turbid samples, and a higher spatial resolution with respect to other laser scanning imaging modalities. The two most used imaging techniques based on nonlinear optical effects are two-photon fluorescence (TPF) and second-harmonic generation (SHG) microscopy. Both TPF and SHG can be used in biological and biomedical imaging by means of signal enhancers such as exogenous fluorophores and harmonophores or by taking advantage of the endogenous tissue components able to emit fluorescence or to generate second-harmonic light.