High-resolution imaging using near-field scanning optical microscopy and shear force feedback in water

Abstract

Near-field scanning optical microscopy using shear force feedback in water is demonstrated with better than 50 nm lateral spatial resolution. Results also indicate the potential to measure topographic features with higher force sensitivity than contact and noncontact atomic force microscopy (AFM) measurements. Soft surface contaminants are clearly imaged using shear force feedback while the simultaneously obtained optical contrast is due to the higher optical density surface features lying beneath the surface contaminants. AFM measurements do not appear to show the same sensitivity to surface features leading to the conclusion that shear force feedback may be better for imaging soft (i.e., low mechanical compliance) samples, such as biological specimens, in liquid.