An image intensifier device includes: an intensifier tube with at least one photocathode, a micro-channel plate and a conversion element, arranged in that order one after another, and an electric power supply module configured to supply at least one respective polarisation voltage to each of the elements of the intensifier tube. The electric power supply module extends in a region located upstream of the photocathode, on the side of the photocathode opposite to the micro-channel plate. Thus, a space is cleared located downstream of the intensifier tube in the direction of travel of the photons and of the electrons in the image intensifier device. This allows reducing the size of the image intensifier device for example by bringing an eyepiece closer.

Disclosed are methods and devices suitable for producing an electron beam.

Disclosed are methods and devices suitable for producing an electron beam.

Vacuum electron devices and linear accelerators include a hollow cathode configured to emit a beam of electrons. An anode is configured to attach and focus the beam of electrons. A control grid is configured to control the beam of electrons emitted from the hollow cathode. A cylinder is positioned substantially coaxial with the hollow cathode and is configured to maintain a shape and trajectory of the emitted beam of electrons.

Vacuum electron devices and linear accelerators include a hollow cathode configured to emit a beam of electrons. An anode is configured to attach and focus the beam of electrons. A control grid is configured to control the beam of electrons emitted from the hollow cathode. A cylinder is positioned substantially coaxial with the hollow cathode and is configured to maintain a shape and trajectory of the emitted beam of electrons.

A tunable photocathode for use in vacuum electronic devices includes a nanostructured photoemission layer including quantum confined nanostructures, such as quantum dots. The quantum confined nanostructures can be tuned (e.g., prepared to have various characteristics or parameters) in order to independently optimize various characteristics of the electron beam emitted by the photocathode. For example, by changing the material composition, size and geometry of the quantum confined nanostructures, the energy levels of the quantum confined nanostructures in the photoemission layer can be tuned to provide a photocathode having a high quantum efficiency, low emittance, fast response time to incident light pulses, long operational lifetime, and increased environmental stability compared with conventional photocathodes and cathodes in vacuum electronic devices.

A tunable photocathode for use in vacuum electronic devices includes a nanostructured photoemission layer including quantum confined nanostructures, such as quantum dots. The quantum confined nanostructures can be tuned (e.g., prepared to have various characteristics or parameters) in order to independently optimize various characteristics of the electron beam emitted by the photocathode. For example, by changing the material composition, size and geometry of the quantum confined nanostructures, the energy levels of the quantum confined nanostructures in the photoemission layer can be tuned to provide a photocathode having a high quantum efficiency, low emittance, fast response time to incident light pulses, long operational lifetime, and increased environmental stability compared with conventional photocathodes and cathodes in vacuum electronic devices.

A photocathode epitaxial structure. The photocathode epitaxial structure includes a binary compound substrate material. The photocathode epitaxial structure further includes an active device absorber layer forming a portion of a p-type device photocathode formed on the binary compound substrate material. The active device absorber layer comprising at least a quaternary or greater material structure configured to be lattice matched with the substrate material to reduce strain to allow charge carriers to go further in the active device absorber layer implemented in the photocathode of a nightvision system.

A photocathode epitaxial structure. The photocathode epitaxial structure includes a binary compound substrate material. The photocathode epitaxial structure further includes an active device absorber layer forming a portion of a p-type device photocathode formed on the binary compound substrate material. The active device absorber layer comprising at least a quaternary or greater material structure configured to be lattice matched with the substrate material to reduce strain to allow charge carriers to go further in the active device absorber layer implemented in the photocathode of a nightvision system.

A photocathode for use in vacuum electronic devices has a bandgap gradient across the thickness (or depth) of the photocathode between the emitting surface and the opposing surface. This bandgap gradient compensates for depth-dependent variations in transport energetics. When the bandgap energy E.sub.BG(z) is increased for electrons with shorter path lengths to the emitting surface and decreased for electrons with longer path lengths to the emitting surface, such that the sum of E.sub.BG(z) and the scattering energy is substantially constant or similar for electrons photoexcited at all locations within the photocathode, the energies of the emitted electrons may be more similar (have less variability), and the emittance of the electron beam may be desirably decreased. The photocathode may be formed of a III-V semiconductor such as InGaN or an oxide semiconductor such as GaInO.