Eucentric height

In an electron microscope, the eucentric height is that position of the sample in which the image of the sample on the luminescent screen does not change when it is tilted.

In order not to unnecessarily restrict the examination possibilities, specimen holders with several degrees of freedom are used. These usually include the three spatial directions indicated by and and two axes of rotation, called and . In order to always be able to see the same section on the fluorescent screen when using the microscope, the electron microscope must be adjusted before starting work. This includes that the goniometer is brought into the eucentric plane. The sample holder is tilted around an axis and its height ( position) is changed until a stable image is obtained on the fluorescent screen. ${\displaystyle \ x,y}$ ${\displaystyle \ z}$ ${\displaystyle \ \alpha }$ ${\displaystyle \ \beta }$ ${\displaystyle \ z}$

The exact eucentric position is an important requirement for an electron microscope. Starting from this level, important parameters such as the zoom factor or camera length are determined.

literature

• Helmut Alexander: Physical basics of electron microscopy . Teubner study books, Stuttgart 1997, ISBN 978-3-519-03221-2 .