Simultaneous third-harmonic generation and three-photon microscopy

Summary form only given. The recent development of third-harmonic generation (THG) microscopy has demonstrated the potential of this technique for dynamic three-dimensional imaging of physical and biological systems, and the technique is already used to study laser-induced breakdown and nematic crystals. While it is known that the THG light is generated at interfaces in index of refraction or third-order nonlinear susceptibility, the exact contrast mechanisms are not yet well understood. In this work, we demonstrate for the first time a microscope that can simultaneously record registered THG and three-photon fluorescence (3PF) images to investigate the contrast mechanisms of THG microscopy compared with those of three-photon fluorescence microscopy. Because the contrast mechanisms differ they provide complementary information, and thus a more detailed view of the specimen results.