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.

An electromagnetic radiation detector includes an inlet window intended to receive a stream of incident photons, as well as a photocathode in the form of a semiconductive layer. A conductive layer is deposited on the downstream face of the inlet window and a thin dielectric layer is disposed between the conductive layer and the semiconductive layer. The conductive layer is brought to a potential below that of the semiconductive layer so as to drive the photoelectrons out of the recombination zone and consequently improve the quantum yield of the photocathode.

An electromagnetic radiation detector includes an inlet window intended to receive a stream of incident photons, as well as a photocathode in the form of a semiconductive layer. A conductive layer is deposited on the downstream face of the inlet window and a thin dielectric layer is disposed between the conductive layer and the semiconductive layer. The conductive layer is brought to a potential below that of the semiconductive layer so as to drive the photoelectrons out of the recombination zone and consequently improve the quantum yield of the photocathode.