Phase Imaging in the Near Field

The near-field scanning optical microscope (NSOM) circumvents diffraction limited resolution imposed on ordinary optical microscopes. We present a novel technique for obtaining simultaneous intensity, topography, and phase images having a lateral resolution of a few tens of nanometers for sample specimens ranging in thickness from a few nanometers to more than one micron. The most recent system utilizes a rotating mirror integrated with an environmentally stabilized, hybrid (part optical fiber, part air path) Mach-Zehnder interferometer for applications involving waveguide analysis, photoresist mask characterization, and biological imaging. Instrument specifications (software, hardware, and optical train) together with images obtained to date are presented.