Imaging small structures substantially below the tissue surface in living specimens poses special challenges mainly because light is scattered by ever present refractive index inhomogeneities. Confocal microscoy removes the blurring caused by scattered and out-of-focus light but does so only at the expense of photodynamic damage that is often unacceptable when observing live specimens.Multi-photon absorption microscopy[l] solves these problems because excitation is virtually limited to the focal plane. Out-of-focus photobleaching and photodamage are therefore eliminated. In scattering samples substantial improvements accrue even for the focal plane because, different from confocal microscopy, where only ballistic fluorescenc photons can be used, in the multi-photon microscope scattered photons can be utilized in addition [2-4], provided whole-field detection is used[5].Many questions in the study of the nervous system require the investigation of intact portions of neural tissue in order to preserve the multiply branched processes of neurons, often extending over hundreds of microns, together with the local nervous circuitry.
High Resolution Imaging of the Human Cardiac Conduction System Using Reflectance Confocal Microscopy
