Pulse excitation light, emitted from a laser light source 10, is scanned
in a first direction by a first scanning means 100, scanned in a second
direction, perpendicular to the first direction, by a second scanning
means 120, converged by an objective optical system 140, and illuminated
onto sample 50. Fluorescences, emitted from sample 50, are output from
objective optical system 140 to second scanning means 120, scanned in the
second direction, perpendicular to the first direction, and output to a
light separation means 110 by second scanning means 120, output from
light separation means 110 to a streak camera, and recorded as variations
of time of the fluorescence intensities by streak camera 30. Fluorescence
lifetimes are calculated based on these variations with time of the
fluorescence intensities and a fluorescence lifetime distribution image
is prepared.