Abstract

The electron microscope has been widely used in many fields, and has becomes useful tool to search the microworld. Unfortunately, it can only be used in the investigation of the static state because of the limitations of the low brightness of the electron beam. In this paper, we suggest equipping an electron microscope with a laser driven photocathode and to let it operate in a cw state or pulse state. The brightness and coherence of the electron beam from a photocathode are as perfect as that of a field emission gun. Moreover, it can also operate in short pulse conditions, 'these advantages are not held by the field emission and thermionic emission gun. As the pulse duration maybe shortened to ps, the requirements for the electron microscope mechanism, the stability of power supply, and the shielding of the space electronmagnetic field can be greatly reduced. So a powerful tool for studying electron holography and the dynamic process is provided.

© 1993 Optical Society of America