Supercritical angle fluorescence microscopy

The method is able to observe molecules in a distance of less than 100 to 0 nanometer from the surface even in presence of high concentrations of fluorescent species around.

Using an aspheric lens for excitation of a sample with laser light, fluorescence emitted by the specimen is collected above the critical angle of total internal reflection selectively and directed by a parabolic optics onto a detector.

[1] When the emitter is located just 200 nm above the surface, fluorescent light entering the solid body above the critical angle is decreased dramatically.

Hence, SAF Microscopy is ideally suited to discriminate between molecules and particles at or close to surfaces and all other specimen present in the bulk.

It is also possible to arrange SAF elements as arrays, and image the output onto a CCD, allowing the detection of multiple analytes.