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.