Super-resolution in two-photon excitation microscopy via saturated excitation

Two-photon excitation microscopy is widely used to observe interiors of biological tissues with utilizing the long penetration and the depth discrimination capability. However, the use of near-infrared light decreases the spatial resolution compared to that in typical fluorescence microscopes using visible light for excitation. The wave distortion and scattering also degrade the spatial resolution in tissue. Although several super-resolution techniques are utilized for two-photon excitation microscopy, improving the spatial resolution in the deep imaging still remains as a challenge.