This article provides insufficient context for those unfamiliar with the subject.(March 2013) |
The 4Pi-STED-microscope is the result of combining the two unrelated concepts of
Stimulated emission depletion (STED) microscopy and
4Pi-microscopy. Here, a
fluorescent sample is placed in the common
focus of two opposing
lenses, but
excitation and
detection are performed through a single lens (4Pi mode A). The green excitation
pulse is immediately followed by a red STED-pulse, which enters the focal region through both lenses inducing stimulated
emission of the excited fluorescent
molecules to the
ground state. To permit fluorescence emission from the center but suppress it from neighbouring regions it is useful to
phase shift the STED beam to have a minimum at the center.