Imaging of liquid crystals using a new scanning near-field optical microscope with microfabricated tips and shear force detection

We report results obtained with a scanning near-field optical microscope which was developed, recently. The scanning head of the device is mounted on an inverted polarizing microscope. The sample is illuminated through a microfabricated tip which is mounted on a single-mode optical wave-guiding fiber. The light transmitted through the sample is collected in the far field by a microscope lens. The distance between the tip and the sample is controlled by shear force detection, using a nonconventional setup. We applied this new equipment successfully in order to investigate birefringent and dichroic liquid crystal films, using polarization modulation or fluorescence detection, respectively. An optical resolution down to ≈200 nm was obtained on the sample of a cholesteric liquid crystal for a wavelength of 488 nm.