Theory - Links

Confocal vs evanescent

Principles of evanescent illumination

Surface plasmons

Label-free detection

Surface plasmon fluorescence spectroscopy

Optical waveguide spectroscopy




Confocal vs. evanescent optical analysis

Optical analysis of biosensing events

A crucial requirement for modern analytical tools, in particular, in the case of biosensing events, are excellent signal-to-noise ratios combined with a high dynamic range of detection. To this, the use of evanescent techniques, such as surface plasmon and optical waveguide spectroscopy, possess distinct advantages over commonly used optical techniques such as confocal microscopy. As illustrated in the figure, using evanescent illumination, one can significantly increase the signal by local field enhancement, while at the same time decreasing any disturbing background, i.e. noise reduction.