  Two-Photon Microscopy has become an invaluable tool for biological and
medical research, providing high sensitivity, molecular specificity, inherent
three-dimensional sub-cellular resolution and deep tissue penetration. In terms
of imaging speeds, however, mechanical scanners still limit the acquisition
rates to typically 10-100 frames per second. Here we present a high-speed
non-linear microscope achieving kilohertz frame rates by employing
pulse-modulated, rapidly wavelength-swept lasers and inertia-free beam steering
through angular dispersion. In combination with a high bandwidth, single-photon
sensitive detector, we achieve recording of fluorescent lifetimes at
unprecedented speeds of 88 million pixels per second. We show
diffraction-limited, multi-modal, Two-Photon fluorescence and fluorescence
lifetime (FLIM), microscopy and imaging flow cytometry with a digitally
reconfigurable laser, imaging system and data acquisition system. These
unprecedented speeds should enable high-speed and high-throughput
image-assisted cell sorting.
