We overcame the resolution limit of scanning far-field fluorescence microscopy by disabling the fluorescence from the outer part of the focal spot. Whereas a near-UV pulse generates a diffraction-limited distribution of excited molecules, a spatially offset pulse quenches the excited molecules from the outer part of the focus through stimulated emission. This results in a subdiffraction-sized effective point-spread function. For a 1.4 aperture and a 388-nm excitation wavelength spatial resolution is increased from 150 ± 8 nm to 106 ± 8 nm with a single offset beam. Superior lateral resolution is demonstrated by separation of adjacent Pyridine 2 nanocrystals that are otherwise indiscernible.
© 1999 Optical Society of America
(000.3110) General : Instruments, apparatus, and components common to the sciences
(180.2520) Microscopy : Fluorescence microscopy
(320.7150) Ultrafast optics : Ultrafast spectroscopy
(350.5730) Other areas of optics : Resolution
Thomas A. Klar and Stefan W. Hell, "Subdiffraction resolution in far-field fluorescence microscopy," Opt. Lett. 24, 954-956 (1999)