SCIENCE AT THE EDGE SEMINAR SERIES Interdisciplinary Physics Seminar Friday, 11 November 2011 at 11:30am Room 1400 Biomedical and Physical Sciences Bldg. Refreshments at 11:15 Speaker: Chris Xu Applied & Engineering Physics, Cornell University Title: Pushing the Limits of Biological Imaging Using Multiphoton Excitation Abstract: Multiphoton microscopy (MPM) has been applied to imaging deep in scattering tissue because of its intrinsic 3D localized excitation. However, the imaging depth of conventional MPM is still limited to less than 1 mm. In this talk, the fundamental difficulties of deep tissue imaging will be discussed. Our research in longer wavelength MPM for deep tissue imaging will be presented in detail. A record 1.6-mm penetration depth is achieved in mouse cortex in vivo. Future directions and preliminary results to further improve the depth limit will be discussed.