STED Microscopy

STED microscopy (STED = Stimulated Emission Depletion), as a high-resolution method operating in scan mode, has special requirements for the properties of its optical components. 

With STED, the specimen is not only exposed to the focused excitation beam, but also simultaneously illuminated with a second laser beam, the "switch-off beam" (depletion or STED pulse). To generate the annular "donut" mode, the lasers must be focused extremely precisely. This requires special specifications of the beam splitters.

For this purpose, AHF analysentechnik offers in cooperation with the filter manufacturer Chroma Technology, beam splitter designs exactly matched to the respective setup. Depending on the setup, the STED laser, for example, is coupled in using a short-pass beam splitter, while the fluorescence-exciting laser beam is coupled in using a long-pass beam splitter. Both must be precisely matched to the wavelength ranges of the lasers and fluorescent dyes used. In addition, a λ/10 surface finish is mandatory. This can only be guaranteed on thick quartz substrates.

Special laser "clean-up" filters, also as short-pass version for TiSa lasers, are available in great variety, this applies accordingly to the specific band-pass filters that are placed in front of the detectors. High edge steepness, maximum transmission and extreme blocking of the lasers used in the STED setup are basic requirements for their specification.

Due to the intensive cooperation with very renowned research groups, the team of AHF has acquired manifold experiences.