The scanning near-field optical microscope allows optical imaging of samples with a resolution below the diffraction limit. This is achieved by scanning the sample surface with an aluminum-coated fiber tip having a sub-wavelength aperture at its end.
Fig. 1 shows a SNOM-Scanner made by the 2. Physikal. Institut of the RWTH Aachen, developed out of our smallest STM including electronics. Instead of measuring the tunneling current a shear force detection is coupled to the STM electronics.
With its small size of only about 4 cm the scanner is almost unaffected by external mechanical vibrations.
Samples under examination at the Institute include ferromagnetic thin films with perpendicular magnetization. Utilizing the Faraday effect, the local magnetization of samples can be measured with high resolution at the Nanometer scale.

The assembly of the tiny sensor in this device is a typical task for our microassembly equipment, see the article "OptoLines" by Spindler & Hoyer