A fully integrated near-field optical, far-field optical, and normal-force scanned probe microscope

Abstract

We present a near-field scanning optical microscope (NSOM) which fully integrates near-field and far-field optics with scanned probe microscopy (SPM). The instrument incorporates a novel, flat scanning system that allows the NSOM/SPM head to be placed directly on the sample stage of any upright or inverted optical microscope and fully integrates the two microscopes. The near-field optical microscope that is designed around this flat scanner utilizes cantilevered optical force sensing probes that we have developed. Thus, the instrument can simultaneously image in a number of topographic and optical modes. The normal force sensing capability of our probes and microscope provides a significant advantage over straight optical fibers and the shear force detection techniques that are employed. The piezoelectric scanner incorporates X, Y, and Z scan ranges of over 40 μm into a flat stage less than 7 mm high. The scanning stage also provides for inertial translation of a sample over many millimeters. This completely and transparently integrates the technologies of near-field optics and other scanned probe microscopies with conventional far-field optical microscopy. Furthermore, the axial positioning capability of the flat scanner enhances the characteristics of the far-field microscope by allowing for three-dimensional optical sectioning that is required in techniques such as confocal imaging, nonlinear optical microscopies, and charge coupled device (CCD) imaging. Finally, the X, Y, and Z precision movements also have the potential for being used in optical tweezer applications.