Abstract
Conventional confocal laser scanning microscopy uses continuous wave visible or UV lasers for one-photon excitation and imaging. These instruments are now enhanced with pulsed infrared lasers allowing two-photon excitation. With the appropriate technical setup two-photon excitation may be used for intensity imaging or for lifetime imaging. Both of these techniques have specific advantages if compared with one-photon excitation. Despite this fact, to date mainly one-photon excitation has been employed in microbial ecology. In this review the potential of two-photon intensity and lifetime imaging is discussed, using appropriate examples from cell biology as well as the first reports in microbiology.
