Fresnel Projection Microscopy, Theory and Experiment: Electron Microscopy with Nanometer Resolution at 200 Volts

Nanotips are used as electron point sources in the Fresnel projection microscope (FPM). The FPM allows imaging in direct space of free standing nanometric fibres at working voltages around 200 V with observation of details of less than one nanometer. These observations are made without irradiation damage, particularly useful for soft materials such as organic or biological molecules (polymers and RNA). Striking new observations of the images of non-opaque fibres in the FPM are presented for the first time. The experimental results are interpreted within the framework of electron optics by taking into account the properties of the nano-objects and the specific field emission properties of nanotips.