The Total Internal Reflection Fluorescence (TIRF) technique is the ideal method for observations of cells close to the coverslip surface. By total reflection of the excitation light (typically laser) at the coverslip / medium interface, the fluorescence emission is limited to a very thin space in the vicinity of the glass surface. The resulting fluorescence images exhibits extremely high contrast and resolution with the  possibility of real-time imaging of cell membranes, actin filament behavior or single molecule tracking.