Abstract
Super-resolution optical microscopy that operates beyond the diffraction limit has become a powerful
tool for investigating biological phenomena. However, it is difficult to achieve super-resolution imaging
at deeper penetration depth in biological tissue. Since the in-focus signal intensity in super-resolution
microscopy is very low, the in-focus signal is buried easily in the background light generated in out-offocus
regions. Therefore, the background suppression techniques are essential for super-resolution deep
imaging. Although nonlinear optical microscopy has the capability to suppress the out-of-focus
background, the out-of-focus background generates in the deep imaging of scattering tissue and limits
the observable imaging depth. We demonstrated not only the resolution enhancement but also the
background suppression in nonlinear optical microscopy by spatio-temporal control of the excitation
pulses.
