A. Jalocha et Nf. Vanhulst, DIELECTRIC AND FLUORESCENT SAMPLES IMAGED BY SCANNING NEAR-FIELD OPTICAL MICROSCOPY IN REFLECTION, Optics communications, 119(1-2), 1995, pp. 17-22
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.