![]() ![]() ![]() For instance, in TEM systems, the sample stages, electron guns, round lenses, objective lens (OL) polepieces, and detectors available in current systems are very similar to the best available in 1980s. Most parts in EMs have not been improved in many years except most of the conventional electron guns have been replaced by the field emission guns and the aberration correctors are introduced recently. Schematic illustration of a TEM system with a slightly different optics in a different way. Schematic of an electron-optical column of a TEM system.įigure 4554b shows the schematic illustration of a TEM system with a slightly different optics in a different way.įigure 4554b. This can either be done at a repetition rate of 3 GHz or 75 MHz depending on single or dual mode operation, respectively.Magnifies image on viewing screen for accurate focusingĪ schematic of an electron-optical column of a TEM isįigure 4554a. Operating at full power the module can deliver 100 fs electron pulses while maintaining the electron beam quality. Additionally the dielectric can be coated to prevent charging due to the electron beam passing through. The deflection cavity is a pillbox cavity partially filled with a dielectric material with a large permittivity ε and a small tan δ, which allows a substantial reduction in size and power consumption. Both modes have an unloaded quality factor that can be as high as Q ≈ 5000. The deflection cavity is a compact, single-cell, power-efficient resonant microwave cavity, supporting a TM-110 mode at a resonance frequency of 2.9985 GHz and a second mode which is orthogonal to the first mode oscillating at a frequency of 3.0735 GHz (difference 75 MHz). This is done by streaking the DC electron beam across a slit using a deflection cavity operated in TM-110 mode. We also offer modules for other electron microscopes, click here to view the other modules. The Titan chopper module can be used to turn a Titan transmission electron microscope into an ultrafast electron microscope. The microscopy system also allows low-dose-rate TEM operation in a very controlled way, which can be beneficial for mitigating radiation damage of sensitive samples. Therefore the spatial resolution of the TEM is the same in pulsed mode and conventional continuous mode. The energy spread of the beam is also minimally affected. By having a cross over in the deflection cavity the growth of the emittance due to chopping is mimimized so that the peak brightness is conserved. The deflection cavity is temperature controlled with 10-30 mK stability by water cooling and the construction of the insert minimizes mechanical vibrations of the deflection cavity. Our microscopy system has been installed and tested in both the Titan and the Tecnai system. We offer modules for both the Titan and the Tecnai system. ![]() ![]() The deflection cavity is part of an insert on a vacuum flange, allowing it to be mounted into the extended column of a Thermo Fisher Scientific TEM. To enable pump-probe experiments, the phase of the oscillating microwave fields in the deflection cavity has to synchronized to the femtosecond pump laser using the synchronizer system. The beam can be chopped either at 3 GHz rep rate using a deflection cavity in single mode or at 75 MHz rep rate using a deflection cavity in dual mode. The microscopy system is based on a deflection cavity to chop the continuous beam from a conventional high-brightness electron gun into ultrashort electron pulses. In addition, the microscopy system allows fast switching between pulsed operation and conventional continuous operation. The microscopy system, developed together with Eindhoven University of Technology, enables ultrafast electron microscopy without the need for an amplified femtosecond laser to generate electron pulses by photoemission. ![]()
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