Nanoscopy describes the ability to see beyond the generally accepted optical limit of 200–300 nm. Stimulated emission depletion (STED) microscopy, developed by Stefan W. Hell and Jan Wichmann in 1994, and experimentally demonstrated by Hell and Thomas Klar in 1999, is a super-resolution technique for nanoscopy. STED microscopy has made considerable progress and is widely used in practical research. But its practical use involves some undesirable background noise, which negatively affects spatial resolution and image quality. In general, this noise comes from two signal sources: (i) fluorescence generated by re-excitation caused by ultrahigh light doses from the depletion beam; and (ii) residual fluorescence, due to insufficient depletion of the inhibition beam.
Click here for original story, Frequency-domain STED microscopy for selective background noise suppression
Source: Phys.org