Berlin 2005 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 50: Imaging and Microscopy

AKB 50.2: Vortrag

Montag, 7. März 2005, 16:15–16:30, TU H2013

Multi Focal 2-Photon Laser Scanning Microscopy of Cells and Biological Tissue — •Jörg Martini, Katja Tönsing, and Dario Anselmetti — University of Bielefeld, Experimental Biophysics, 33615 Bielefeld, Germany

Near infrared 100fs laser pulses focussed through a high numerical aperture objective lens provide an energy density, that is high enough to induce 2-photon excitation of native fluorophors and fluorescent dyes in the focal volume. By scanning the back aperture of the objective lens with the laser beam, confocal like collection of the fluorescence signal from a single optical plane up to hundreds of µm inside the sample is possible. Varying the distance between the lens and sample, i.e. measuring a depth dependent stack of optical planes, produces a 3D fluorescence scan of the sample with sub µm resolution. The output of today’s Ti:Sa-lasers in the focal volume is much higher than the destruction threshold of almost all biological samples. By splitting up the laser power and directing several beams into the objective lens, we create up to 64 foci in the sample. This setup allows for short acquisition times while minimizing the photo damage to the sample. We will present our results on the 3D-distribution of fluorescence and second harmonic generation signal in single cells and biological tissue and their spectral properties.