High-speed multiframe dynamic transmission electron microscope image acquisition system with arbitrary timing

An electron microscope comprising:

• a laser-driven photocathode;
• an arbitrary waveform generation (AWG) laser system for producing a train of temporally-shaped laser pulses having programmable pulse durations and programmable inter-pulse spacings, and arranged to direct the laser pulses to the laser-driven photocathode for producing a train of electron pulses;
• a first lens stack arranged to focus the train of electron pulses to a sample;
• a second lens stack producing a magnified image or diffraction pattern of the sample on an image sensor;
• an image sensor;
• a control system;
• a deflector subsystem controlled by the control system, the deflector subsystem having a first pair of spaced apart electrostatic deflector plates and a second pair of spaced apart deflector plates arranged perpendicular to the first pair of electrostatic deflector plates, both said pairs of electrostatic deflector plates being arranged downstream of the sample and upstream of the image sensor;
• independent first and second voltage supplies controlled by the control system and being synchronized with the AWG laser system;
• a plurality of switching elements controlled by the control system for generating switching signals to independently control an application of high voltage signals to each one of the deflector plates of both said pairs of deflector plates;
• and
• the control system configured to independently and rapidly reversibly switch the high voltage signals applied to each of the deflector plates in synch with the train of laser pulses so as to direct each electron pulse to a different portion of the image sensor to capture a high-speed sequence of images or diffraction patterns of the sample.

A method for performing dynamic transmission electron microscopy (DTEM) comprising:

• providing a laser-driven photocathode;
• using an arbitrary waveform generation (AWG) laser system to generate a train of temporally-shaped laser pulses having programmable pulse durations and programmable inter-pulse spacings, the temporally-shaped laser pulses being directed at the laser-driven photocathode for producing a train of electron pulses emitted from the laser-driven photocathode;
• focusing the train of electron pulses to a sample;
• using an image sensor to receive the train of electron pulses downstream of the sample, and after the train of electron pulses has impinged the sample;
• using a deflector subsystem having a first pair of deflector plates and a second pair of electrostatic deflector plates arranged perpendicular to the first pair of deflector plates, and where the first and second pairs of deflector plates are arranged downstream of the sample but upstream of the image sensor, to controllably deflect the train of electron pulses onto selected subportions of the image sensor, and
• using a control system that is i) in communication with both the AWG laser system and the deflector subsystem and ii) in communication with a plurality of switching components to synchronize the AWG laser system and the deflector subsystem, to:
• rapidly and reversibly switch voltage signals applied to each one of the deflector plates to independently control excitation of each one of the deflector plates to synch operation of the deflector subsystem with the train of laser pulses, so as to direct each said electron pulse to a different portion of the image sensor to capture a high-speed sequence of images or diffraction patterns of the sample;
• and
• to provide each said electron pulse with an independently set duration controlled by the control system;
• and
• to provide spacings between sequentially generated ones of the electron pulses that are variable and independently controllable by the control system.