REFLECTION NEAR-FIELD SCANNING OPTICAL MICROSCOPY - AN INTERFEROMETRIC APPROACH

An all-fiber near-field scanning optical microscope (NSOM) is demonstr ated which allows significant signal enhancement through interferometr ic mixing and permits phase contrast. An uncoated fiber tip is used bo th as source and detector in a reflection mode configuration. Pseudohe terodyne detection in a Mach-Zehnder interferometer used in conjunctio n with the reflection mode NSOM allows the imaging of both opaque and transparent samples with a large signal enhancement. A phase contrast can be observed that may prove useful in the imaging of certain sample s such as biological specimens. Images of a diffraction grating and re d blood cells are presented in three different operating modes: conven tional reflection, reflection with enhanced amplitude contrast, and re flection with phase contrast.