Side Views in 3D Live Cell Microscopy

Abstract

Commonly trans-illumination or epi-illumination techniques are used in optical microscopy, e.g. phase microscopy, fluorescence microscopy or inelastic light scattering (Raman microscopy). However, an increasing number of applications requires optical excitation perpendicular or under a certain angle to the optical axis. Methods include Mie Scattering Microscopy with angular resolution for label-free studies of cell or tissue morphology as well as Total Internal Reflection Fluorescence (TIRF) Microscopy with an evanescent electromagnetic field penetrating only about 100 nm into a sample and permitting selective studies of cell surfaces, e.g. membranes. Presently, conventional wide field or confocal microscopy are often replaced by Light Sheet Fluorescence Microscopy (LSFM) where individual planes of a specimen are illuminated from the side without any light exposure or phototoxic damage of adjacent parts of the sample. Finally, Axial Tomography permits samples to be observed from various sides with a high and isotropic resolution in all three dimensions. All these methods require experimental setups which are not integrated in conventional microscopes. Therefore, we report on some technical solutions implemented in specific modules or add-ons for these microscopes.