Additive noise fluorescence imaging systems

The next step was to improve the stability of the system and - even more importantly - to improve the transmission of the fiber tips. Metalization of the tip is the key and produces superior properties, such as a near-field spot of less than 20 nm [107-110]. Zeisel et al. reported that metalization led to optical transmission of a fiber higher than that of conventional fibers by several orders of magnitude [111]. The authors showed images based on the fluorescence of dye-labeled polystyrene spheres and noted that fast and irreversible photobleaching takes place in the near field with enhanced intensity. In addition, they reported on surface-enhanced near-field Raman spectra of cresol fast violet and p-aminobenzoic acid adsorbed on a (rough) silver substrate, exhibiting a signal-to-noise ratio of >10 [111]. 

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