Abstract: In an electron tube, the meta-surface emits an electron in response to an incidence of the electromagnetic wave. The first and second electrodes are spaced away from each other, and apply potentials different from each other to the meta-surface. A holder is disposed in the housing and holds the electron emitter. A first conductive line of the meta-surface is electrically connected to the first electrode. A second conductive line of the meta-surface is spaced away from the first conductive line, and is electrically connected to the second electrode. The first conductive line extends from the first electrode to the second conductive line. The second conductive line extends from the second electrode to the first conductive line.

Abstract: An electron tube includes a housing that is internally held in a vacuum and has a window transmitting an electromagnetic wave, an electron emitting unit that is disposed in the housing and has a meta-surface emitting electrons in response to incidence of the electromagnetic wave, an electron multiplying unit that is disposed in the housing and multiplies the electrons emitted from the electron emitting unit, and an electron collecting unit that is disposed in the housing and collects the electrons multiplied by the electron multiplying unit. The window contains at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide, and calcium carbonate.

Abstract: This invention concerns a photo-cathode for a vacuum system, wherein the photo-cathode is configured for receiving electromagnetic radiation having an incoming wavelength and for emitting electrons in response thereto. The photo-cathode comprises a conducting structure having a geometry, the geometry comprising a tip section. The tip section is adapted to provide field enhancement, ?, when the conducting structure is illuminated with the electromagnetic radiation, wherein ? is greater than about 102. The photo-cathode further comprising a substrate, the substrate being or comprising a dielectric substrate, the substrate supporting the conducting structure.