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.

The present invention addresses the problem of providing a method for automatically adjusting an electron beam emitted from an electron gun equipped with a photocathode to the incident axis of an electron optical system. [Solution] An incident axis alignment method for an electron gun equipped with a photocathode, the electron gun being capable of emitting an electron beam in a first state due to the photocathode being irradiated with excitation light, and the method including at least an excitation light radiation step, a first excitation light irradiation position adjustment step for changing the irradiation position of the excitation light on the photocathode and adjusting the irradiation position of the excitation light, and an electron beam center detection step for detecting whether a center line of the electron beam in the first state coincides with an incident axis of an electron optical system.

The present invention addresses the problem of providing a method for automatically adjusting an electron beam emitted from an electron gun equipped with a photocathode to the incident axis of an electron optical system. [Solution] An incident axis alignment method for an electron gun equipped with a photocathode, the electron gun being capable of emitting an electron beam in a first state due to the photocathode being irradiated with excitation light, and the method including at least an excitation light radiation step, a first excitation light irradiation position adjustment step for changing the irradiation position of the excitation light on the photocathode and adjusting the irradiation position of the excitation light, and an electron beam center detection step for detecting whether a center line of the electron beam in the first state coincides with an incident axis of an electron optical system.

An electron beam source includes a photocathode or an anode attached to an ultraviolet semiconductor light source (SULS), or an anode incorporated between a SULS and a photocathode, and an electron beam gun using the electron beam source and electron beam pumped target. In certain embodiments the target is an electron beam pumped light emitting device. The photocathode surface is essentially parallel to the surface of the SULS which is a Light Emitting Diode, Superluminescent Diode, or Laser Diode. Different embodiments of the present disclosure include a photocathode directly attached to the SULS surface or having an intermediate transition layer or layers between the photocathode and the emitter. The transition layer includes a substrate on which the SULS is fabricated and/or a layer to facilitate light extraction from the SULS to the photocathode. The active region of the electron beam pumped light emitter is placed in the path of photoelectron flow to excite non-equilibrium electron-hole pairs and generate light emission at a wavelength or wavelengths determined by the energy band structure of the active region.

An electron beam source includes a photocathode or an anode attached to an ultraviolet semiconductor light source (SULS), or an anode incorporated between a SULS and a photocathode, and an electron beam gun using the electron beam source and electron beam pumped target. In certain embodiments the target is an electron beam pumped light emitting device. The photocathode surface is essentially parallel to the surface of the SULS which is a Light Emitting Diode, Superluminescent Diode, or Laser Diode. Different embodiments of the present disclosure include a photocathode directly attached to the SULS surface or having an intermediate transition layer or layers between the photocathode and the emitter. The transition layer includes a substrate on which the SULS is fabricated and/or a layer to facilitate light extraction from the SULS to the photocathode. The active region of the electron beam pumped light emitter is placed in the path of photoelectron flow to excite non-equilibrium electron-hole pairs and generate light emission at a wavelength or wavelengths determined by the energy band structure of the active region.

A night vision system along with an image intensifier tube and method for forming the tube are provided. The night vision system incorporates the image intensifier tube in both an analog channel as well as a digital channel, with an addressable display within the analog image intensifier tube analog channel configured to create an electronically addressable output. An analog image intensifier tube is included in the digital imager for presenting binary digital signals representative of an image, or of symbol indicia, and registering those digital representation from the digital imager onto one or more electron multipliers of the analog image intensifier tube within the analog channel. The provided night vision system also utilizes a cathodoluminescent screen, which is a highly efficient light source that reduces system power.

A night vision system along with an image intensifier tube and method for forming the tube are provided. The night vision system incorporates the image intensifier tube in both an analog channel as well as a digital channel, with an addressable display within the analog image intensifier tube analog channel configured to create an electronically addressable output. An analog image intensifier tube is included in the digital imager for presenting binary digital signals representative of an image, or of symbol indicia, and registering those digital representation from the digital imager onto one or more electron multipliers of the analog image intensifier tube within the analog channel. The provided night vision system also utilizes a cathodoluminescent screen, which is a highly efficient light source that reduces system power.

In a photoexcited electron source, a condenser lens optimally designed on an assumption that excitation light passes through a transparent substrate having a predetermined thickness and a predetermined refractive index cannot focus a focal point of the excitation light well on a photocathode film when the transparent substrate is different. Therefore, an optical spherical aberration correction plate 21 having a refractive index equal to a refractive index of a substrate of a photocathode at a wavelength of the excitation light is disposed between the photocathode 1 and the condenser lens 2. Alternatively, an optical spherical aberration corrector 20 configured to diverge or focus parallel light emitted to the condenser lens is provided. Accordingly, flares of the electron beam can be reduced and brightness of the photoexcited electron source can be increased.

In a photoexcited electron source, a condenser lens optimally designed on an assumption that excitation light passes through a transparent substrate having a predetermined thickness and a predetermined refractive index cannot focus a focal point of the excitation light well on a photocathode film when the transparent substrate is different. Therefore, an optical spherical aberration correction plate 21 having a refractive index equal to a refractive index of a substrate of a photocathode at a wavelength of the excitation light is disposed between the photocathode 1 and the condenser lens 2. Alternatively, an optical spherical aberration corrector 20 configured to diverge or focus parallel light emitted to the condenser lens is provided. Accordingly, flares of the electron beam can be reduced and brightness of the photoexcited electron source can be increased.

A photocathode is formed on a monocrystalline silicon substrate having opposing illuminated (top) and output (bottom) surfaces. To prevent oxidation of the silicon, a thin (e.g., 1-5 nm) boron layer is disposed directly on the output surface using a process that minimizes oxidation and defects. An optional second boron layer is formed on the illuminated (top) surface, and an optional anti-reflective material layer is formed on the second boron layer to enhance entry of photons into the silicon substrate. An optional external potential is generated between the opposing illuminated (top) and output (bottom) surfaces. The photocathode forms part of novel electron-bombarded charge-coupled device (EBCCD) sensors and inspection systems.