A novel method and system for conducting wide-field multi-photon microscopy through plane-projection are provided. It has been discovered that the limitations of conventional temporal-focusing techniques, such as single excitation wavelength and low acquisition rates can be resolved utilizing a novel optical set-up in which an optical diffuser is used as the scatterer. The use of such an optical arrangement enables temporal focusing regardless of the central wavelength of laser pulses. In addition, the optical sectioning possible using the disclosed microscopy is comparable to confocal microscopy, and can be robustly achieved by both moderate and high NA objectives at 100-fs pulse width. Moreover, the multi-photon excitation efficiency of the disclosed system can be enhanced by lowering the repetition rate of the ultrafast laser light source at constant pulse width and average power.