STED microscopy enhances resolution by using a second laser for stimulated depletion (STED = STimulated Emission Depletion). The transversal profile of the second laser is modulated so that a ring is formed in the external region of the excitation spot, which has a zero in its center. Since this narrows the effective excitation focus, resolution is enhanced.
Our STED microscope is a STEDYCON of Abberior Instruments GmbH (http://www.abberior-instruments.com/products/compact-line/). The STEDYCON is an attachment that can be mounted on the camera port of a microscope, turning the microscope into a 2D STED and also a confocal microscope. Its resolution in STED mode is below 40 nm in both x and y direction. Along the z axis the microscope has confocal resolution (~ 500 nm).
The microscope is equipped with three pulsed excitation lasers (diode lasers at 450, 594, and 640 nm) and a pulsed STED laser (fiber laser at 775 nm).