Abstract: One embodiment pertains to an apparatus for compressing an electron pulse. An electron source is illuminated by a pulsed laser and generates a pulse of electrons. The pulse enters a beam separator which deflects the electrons by 90 degrees into an electron mirror. The faster, higher energy electrons form the leading edge of the pulse and penetrate more deeply into the retarding field of the electron mirror than the lower energy electrons. After reflection, the lower energy electrons exit the electron mirror before the higher energy electrons and form the leading edge of the pulse. The reflected pulse reenters the separator and is deflected by 90 degrees towards the specimen. The fast, higher energy electrons catch up with the slow, low energy electrons as the electrons strike the specimen. The electrons are scattered by the specimen and used to form a two-dimensional image or diffraction pattern of the specimen.

Abstract: One embodiment relates to an apparatus for correcting aberrations introduced when an electron lens forms an image of a specimen and simultaneously forming an electron image using electrons with a narrow range of electron energies from an electron beam with a wide range of energies. A first electron beam source is configured to generate a lower energy electron beam, and a second electron beam source is configured to generate a higher energy electron beam. The higher energy beam is passed through a monochromator comprising an energy-dispersive beam separator, an electron mirror and a knife-edge plate that removes both the high and low energy tail from the propagating beam. Both the lower and higher energy electron beams are deflected by an energy-dispersive beam separator towards the specimen and form overlapping illuminating electron beams. An objective lens accelerates the electrons emitted or scattered by the sample.

Abstract: One embodiment relates to an apparatus for forming an electron image using electrons with a narrow range of electron energies from an electron beam with a wide range of energies. An electron beam source is configured to generate an electron beam, and condenser lenses collimate the beam into an objective lens configured to illuminate the specimen. The illuminating electrons are scattered by the specimen and form an electron beam with a range of energies that enter a magnetic prism separator. After a 90 degree deflection, the prism separator introduces an angular dispersion that disperses the incoming electron beam according to its energy. A knife-edge plate removes either the high or low energy tail from the propagating beam. An electron lens is configured to focus the electron beam into an electron mirror so that after the reflection, the other energy tail is stopped on the same knife-edge plate.

Abstract: One embodiment relates to an apparatus for generating two spatially overlapping electron beams on a specimen. A first electron beam source is configured to generate a low-energy electron beam, and an energy-dispersive device bends the low-energy electron beam towards an semitransparent electron mirror. The semitransparent electron mirror is biased to reflect the low-energy electron beam. A second electron beam source is configured to generate a high-energy electron beam that passes through an opening in the semitransparent electron mirror. Both the low- and high-energy electron beams enter the same energy-dispersive device that bends both beams towards the specimen. A deflection system positioned between the high-energy electron source and semitransparent electron mirror is configured to deflect the high-energy electron beam by an angle that compensates for the difference in bending angles between the low- and high-energy electron beams introduced by the energy-dispersive device.