DIELECTRIC AND FLUORESCENT SAMPLES IMAGED BY SCANNING NEAR-FIELD OPTICAL MICROSCOPY IN REFLECTION

Dielectric fluorescent samples are imaged by scanning near-field optic al microscopy in reflection. A non-metallized tapered fibre tip is use d both as an emitter and a detector. Shear force feedback controls the distance between the tip and the sample and gives simultaneously a to pographic image of the surface. A direct correlation with the optical image is obtained. We demonstrate that this reflection setup is suitab le for dielectric samples. Images in fluorescence have been obtained o n Langmuir-Blodgett films. For fluorescence detection the optical cont rast is unambiguous, and consequently we estimate the detecting size o f the probe at about 200 nm. Operation in reflection opens new possibi lities since it allows the study of metallic, thick, opaque or dielect ric sample and can be easily combined with a transmission setup. In th is way, biological samples can be imaged optically simultaneously in t ransmission, reflection and with a shear force control.