This section is still under construction and will be updated continously……..
In conventional electron microscopy, single micrographs (projection images) of the specimen are acquired, which by themselves only provide two-dimensional information on the observed object. In electron tomography a so-called tilt series is acquired; the specimen is rotated within the microscope in a defined range, e.g. from -60° to +60° degrees. Every other degree an image is obtained. The sequence of image acquisition in a tilt series depends on the objective, i.e. speed of acquisition vs data quality.
The images of a tilt series, together with the geometrical information of how these images are related to each other, allows to generate a three-dimensional volume (called a tomogram) of the object. How this is done and how this looks is described here.
The video below displays the sequence of image acquisition for a tilt series. The acquisition starts at the 0 degree tilt angle and then moves gradually up to the maximum tilt angles at -60°/+60° degrees in 3° degree steps.