Institut Fresnel

The procedure to trap a small object with a tungsten tip is therefore the following : TE illumination is used while the tip scans the surface in tapping mode or in constant-height mode if the area under investigation is small enough. Such modes avoid the displacement of the particle by the tip. Once an object has been selected, the probe is placed above the object and the polarization of the illumination is rotated to TM. The probe is then brought down over the particle and captures it. The probe can then move the particle above the substrate, both horizontally and vertically, to a new position where it can be released by switching back to TE polarization.