A Near-Field Scanning, Phase-Contrast Microscope

University Of North Carolina At Charlotte, Charlotte NC

Investigators

Abstract

This grant provides funding for the development of a near-field scanning optical microscope (NSOM) which utilizes a unique phase-contrast mechanism. The standard NSOM, available commercially, has allowed the range of visible light microscopy to be extended into the nanometer range of spatial resolution normally reserved for electron microscopes. However, unlike the electron microscope, an NSOM can image specimens in their natural environment (i.e., liquids and ambient pressures) and can obtain scanning force surface profiles simultaneous with intensity images. An NSOM takes advantage of the same contrast mechanisms available to conventional far-field methods (i.e., fluorescence, transmission, polarization, spectroscopy, reflectivity, and phase). The instrument proposed here would combine standard NSOM operation with pure phase imaging to provide a novel quantifiable NSOM phase-contrast measuring instrument useful for the metrology of a broad range of micro and meso scale devices. Measurement of objects at a molecular or near molecular scale is becoming increasingly important in many disciplines. These objects range from engineering surfaces, such as optical discs, magnetic disks, integrated circuits, and diamond turned optics to catalytic arrays of platinum, DNA molecules, cell biology, and nanoscale flaws in crystals. Far-field phase microscopy is currently a workhorse method of analysis in all of these areas. Success of this project will extend phase microscopy into the nanometer region. Particular systems to be studied in this work include biological cells, photoresist masks, and optical fibers. The semiconductor industry roadmap calls for 70-nm linewidths, which cannot be quantifiably measured with current optical methods. In addition, with the rapid growth of the optical fiber industry, determination of index of refraction profiles of optical fibers with 50-nm resolution will help manufacturers with fiber design and quality control processes. Combined with the need for higher spatial resolution analytical tools, success of this particular project will be of value to many disciplines.