Aberration measurement and correction for ultrafast two-photon fluorescence imaging

An ultrafast two-photon fluorescence microscope utilizing free-space angular-chirp-enhanced delay (FACED) can achieve megahertz line-scan rates and kilohertz frame rates, thus capturing fast biological events such as electrical activity in the brain. However, distortion of the excitation light wavefront caused by optical aberration reduces image signal, contrast, and resolution. In this work, we used adaptive optics (AO) to measure and correct the aberration experienced by FACED excitation foci from both the optical system and the sample. Furthermore, we applied AO FACED two-photon fluorescence microscopy to in vivo activity imaging of neurons.