A novel and powerful method to study the optical properties of thin lipid films which a resolution superior to confocal microscopy is presented. With a scanning near-field optical microscope, fluorescence images of a Langmuir-Blodgett film of diethylene glycol diamine pentacosadiynoic amide are obtained with a lateral resolution of 100 nm. Simultaneously a force image is measured that gives the topography. Therefore it is possible to correlate a high-resolution fluorescence micrograph with the topological structure of the polymer film. Polymer domains that do not fluoresce are visible in the force image, while polarization dependence, an optical property not afforded by atomic force microscopy, is clearly demonstrated with a high resolution in the near-field optical image. This combination of fluorescence scanning near field optical microscopy and force microscopy provides additional information on the structure of the polymer film that can be valuable in the research of Langmuir-Blodgett films.

Operation of an alternative near-field optical microscope is presented. The microscope uses a microfabricated silicon-nitride probe with integrated cantilever, as originally developed for force microscopy. The cantilever allows routine close contact near-field imaging on arbitrary surfaces without tip destruction. The effect of adhesion forces on the coupling to the evanescent wave has been observed. Images with a lateral resolution of about 50 nm are presented and compared with atomic force images. A specific sample area can be selected using an integrated conventional light microscope.

Chromosomes, DNA, and single fluorescent molecules are studied using an aperture-type near-field scanning optical microscope with tuning fork shear force feedback. Fluorescence in situ hybridization labels on repetitive and single copy probes on human metaphase chromosomes are imaged with a width of 80 nm, allowing their localisation with nanometer accuracy, in direct correlation with the simultaneously obtained topography. Single fluorophores, both in polymer and covalently attached to amino-silanized glass, are imaged using two-channel fluorescence polarization detection. The molecules are selectively excited according to their dipole orientation. The orientation of the dipole moment of all molecules in one image could be directly determined. Rotational dynamics on a 10-ms to 100-s timescale is observed. Finally, shear force imaging of double-stranded DNA with a vertical sensitivity of 0.2 nm is presented. A DNA height of 1.4 nm is measured, which indicates the nondisturbing character of the shear force mechanism.

Summary Near‐field optical microscopy is the optical alternative of the various types of scanning probe microscopes. The technique overcomes the classical diffraction limit in conventional optical microscopy. In this paper the concepts of near‐field optics (NFO) are introduced, followed by a short review of current trends in NFO microscopy. Specifically, developments concerning the efficiency and versatility of both aperture and dielectric probe types are discussed. We present our advances in NFO microscopy, using both fibres and integrated silicon nitride (SiN) structures as dielectric probes. The use of an SiN probe as a combined optical and force sensor is shown to be advantageous, as it provides a feedback mechanism and allows direct comparison between topography and dielectric effects. Images of technical and biological samples are presented with a lateral resolution down to 20 nm, depending on the microscopical arrangement used.

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