Abstract
Electron microscope has become a pivotal instrument in materials, chemical, and biological field. But now, we use the single-electron packets to develop 4D ultrafast electron microscope, that the 4D-EM not only held the function of conventional EM, but also provides the structural of dyn- amic image and combined with spatial and temporal resolution . Because single-electron packets have no space- charge effect,and Boerch effect images patterns can observe with atomic- scale spat- ial resolution, and temporal resoluyion that is determined by the ultrafast laser pulses duration can achieve pico- or femtosecond scale. We also call ultrafast electron microscope as 4D electron microscope，because it improve more temporal resolution than conventional electron microscope，and we can observe the transient chan- ge。We hope that we will apply in materials science、chemical reaction or even in research of me- dical science。 In the research we design the electron gun chamber, deflection plate, sub-nanosecond electron switch and combined with MCP. Electrons are exciting from probe by ultrafast laser and focus on the specimen to produce electron signal. The electron signal deflects by adding electron field that is controlled by electron-optic switch in few picosecond and produce dispersion to separate the signal. The final signal is amplified when goes through MCP (multi channel plate), and detected by phos- phor screen. We expect the current will increase by adding ultrafast laser. It will verify that ultrafast laser change the current of electron beam.