Abstract: A scanning electron beam apparatus which two-dimensionally scans a sample by an electron beam to achieve high resolution even with a photoexcited electron source. The electron beam apparatus includes a photocathode including a substrate having a refractive index of more than 1.7 and a photoemissive film, a focusing lens configured to focus an excitation light toward the photocathode, an extractor electrode disposed facing the photocathode and configured to accelerate an electron beam generated from the photoemissive film by focusing the excitation light by the focusing lens and emitting the excitation light through the substrate, and an electron optics including a deflector configured to two-dimensionally scan a sample by the electron beam accelerated by the extractor electrode. For a spherical aberration of the focusing lens, a root mean square of the spherical aberration on the photoemissive film is equal to or less than 1/14 of a wavelength of the excitation light.

Abstract: A method of making leak tight electrical connections through the wall of a ceramic package, for example a ceramic package used on an image intensifier tube. The method comprises a hole metallisation step (500) to obtain vias, the metallisation step comprising the deposition of a bond layer (510), a diffusion barrier (520) acting as a metallic base layer and a wetting agent (530). For each via, a filler metal preform made of indium or a eutectic chosen from among InSn, AuSn, AuGe, AgSn is deposited (540) on each orifice and is heated to a temperature higher than its melting temperature (550) such that the molten filler metal closes off the via to make it leak tight.

Abstract: The photocathode lighting device of planar light emission including: a light source unit emitting a first light; a cathode plate contacted face-to-face with the light source unit; a metal mask layer adhered to the cathode plate and including a repetitive plurality of apertures; a photocathode formed on a surface of the metal mask layer, receiving the first light, and emitting an electron; an anode plate facing the cathode plate and spaced apart from the cathode plate; and a phosphor formed in a lower part of the anode plate and emitting a second light when the emitted electron collides with the phosphor.

Abstract: A multifunction module for an electron beam column comprises upper and lower electrodes, and a central ring electrode. The upper and lower electrodes have multipoles and are capable of deflecting, or correcting an aberration of, an electron beam passing through the electrodes. A voltage can be applied to the central ring electrode independently of the voltages applied to the upper and lower electrodes to focus the electron beam on a substrate.

Abstract: When to-be-detected light is made incident from a support substrate 2 side of a photocathode E1, a light absorbing layer 3 absorbs this to-be-detected light and produces photoelectrons. However, depending on the thickness and the like of the light absorbing layer 3, the to-be-detected light can be transmitted through the light absorbing layer 3 without being sufficiently absorbed by the light absorbing layer 3. The to-be-detected light transmitted through the light absorbing layer 3 reaches an electron emitting layer 4. A part of the to-be-detected light that has reached the electron emitting layer 4 proceeds toward a through-hole 5a of a contact layer 5. Since the length d1 of a diagonal line of the through-hole 5a is shorter than the wavelength of the to-be-detected light, the to-be-detected light can be suppressed from passing through the through-hole 5a and being emitted to the exterior.

Abstract: The invention relates to the correction of the distortion of an image intensifier electron tube comprising an entry screen intended to receive what is called primary electromagnetic radiation and an exit screen emitting radiation dependent on the primary radiation, the entry screen including a photocathode that emits an electron beam in the tube toward the exit screen, the emission of the electron beam being dependent on the primary radiation. The entry screen furthermore includes a test pattern formed from a plurality of dots distributed over the entry screen, the test pattern comprising means for locally altering the electron beam without altering the primary radiation.

Abstract: A streak tube 1A comprises an envelope 10 including an entrance faceplate 12; a photocathode 20 for converting light received from the entrance faceplate 12 into an electron; an anode 23 having an opening 23a for passing there through the electron emitted from the photocathode 20; deflecting electrodes 24 for controlling a deflection of the electron having passed through the opening 23a of the anode; and a fluorescent screen 25 for detecting a streak image due to the electron having the deflection controlled by the deflecting electrodes 24. The photocathode 20 is configured so as to be kept from directly facing the anode 23 on an axis of an electric field formed between the entrance faceplate 12 and the anode 23 or on a tube axis passing the center of the opening 23a in the anode 23 within the envelope 10. Thus, the streak tube capable of suppressing influences of noise signals on signals corresponding to incident light can be realized.

Abstract: An electron beam column comprises a thermal field emission electron source to generate an electron beam, an electron beam blanker, a beam shaping module, and electron beam optics comprising a plurality of electron beam lenses. In one version, the optical parameters of the electron beam blanker, beam shaping module, and electron beam optics are set to achieve an acceptance semi-angle ? of from about ¼ to about 3 mrads, where the acceptance semi-angle ? is half the angle subtended by the electron beam at the writing plane. The beam-shaping module can also operate as a single lens using upper and lower projection lenses. A multifunction module for an electron beam column is also described.

Abstract: An image display device is provided in which the overall brightness of an image can be varied without adversely affecting hue and contrast. The image display device includes emitters 16 connected to a cathode electrode 15, a gate electrode 13, an anode electrode 3, transistors Tr1 and Tr2, and a capacitor 12. A voltage applied to the capacitor 12 is varied to display an image. A constant voltage is applied to the gate electrode 13 to change a time ratio Du. Thus, the overall brightness of an image can be adjusted.

Abstract: A limiter device is used as a fiber optic faceplate (FOFP) night vision goggle for limiting light or laser induced damage on a vacuum side of the FOFP. The limiter device includes a plurality of longitudinally extending optical fibers, each bundled to each other to form a light input surface on an external side of the FOFP and a light output surface on the vacuum side of the FOFP. The optical fibers include fiber optic cores and a glass cladding surrounding each of the cores. A portion of the glass cladding is replaced by an optical absorber material extending longitudinally away from the light input surface. The optical absorber material may extend longitudinally about 1-20 microns away from the light input surface.

Abstract: An electron beam lithography system has an electron gun including at least one laser that is operable in a first mode to generate electrons for lithography. The electron beam lithography system is operable in a second mode to regenerate the photocathode of the electron gun by application of the laser. The photocathode includes a layer of cesium telluride.

Abstract: In the polycrystal diamond thin film in accordance with the present invention, the average particle size is at least 1.5 ?m and, in a Raman spectrum obtained by Raman spectroscopy, a peak intensity near a wave number of 1580 cm?1 has a ratio of 0.2 or less with respect to a peak intensity near a wave number of 1335 cm?1. The photocathode and electron tube in accordance with the present invention comprise the polycrystal diamond thin film as a light-absorbing layer.

Abstract: The invention relates to the correction of distortion in an image intensifier comprising a primary screen intended for receiving first radiation and a secondary screen that emits second radiation that depends on the first radiation. The image intensifier furthermore includes means for projecting, onto the primary screen, a location test pattern produced using third radiation, and the secondary screen emits an image that depends on the location test pattern.

Abstract: An electron beam source has a photocathode with a photoemitter material having a work function, and with a beam receiving portion and an electron emitting portion. A first light source directs a first light beam onto the beam receiving portion of the photocathode to generate an electron beam from the electron emitting portion. The first light beam has a wavelength ?1 such that hc/?1 is at least about the work function of the photoemitter material, where ‘h’ is Planck's constant and ‘c’ is the speed of light. A second light source directs a second light beam onto the beam receiving portion of the photocathode, such as onto the beam receiving portion, to stabilize the electron beam. The second light beam having a wavelength ?2 such that hc/?2 is less than about the work function of the photoemitter material.

Abstract: An X-ray light emitting phosphor film (22) such as a CsI film that converts an X-ray to light is formed on an input substrate (21) constituting an input part of an X-ray image detector. A surface portion of the X-ray light emitting phosphor film (22) is irradiated with high-energy light having a wavelength of 500 nm or less. The surface portion of the X-ray light emitting phosphor film (22) is locally sublimated and/or fused to be flattened by the irradiation with the high-energy light. The use of the high-energy light such as a laser beam makes it possible to efficiently and uniformly flatten the surface portion of the X-ray light emitting phosphor film.

Abstract: A housing for microelectronic devices requiring an internal vacuum for operation, e.g., an image detector, is formed by tape casting and incorporates leads between interior and exterior of said housing where said leads are disposed on a facing surface of green tape layers. Adjacent green tape layers having corresponding apertures therein are stacked on a first closure member to form a resulting cavity and increased electrical isolation or channel sub-structures are achievable by forming adjacent layers with aperture dimension which vary non-monotonically. After assembly of the device within the cavity, a second closure member is sealed against an open face of the package in a vacuum environment to produce a vacuum sealed device.

Abstract: A photocathode and an electron tube in which the photocathode plate can be securely fixed without using any adhesive. Even under the severe condition that a high vibration resistance is required or thermal stress occurs because of great temperature variation, it can be used widely for an image intensifier, a streak tube, or a photomultiplier. The photocathode plate of the photocathode is sandwiched between a faceplate and a support plate. First pins embedded in the faceplate are joined to the support plate. Therefore, the photocathode plate can be readily fixed securely to the faceplate without using any adhesive.

Abstract: A image intensifier tube (14) includes a housing (18) carrying a photocathode (22) and a microchannel plate (24). The housing also receives axially extending fine-dimension spacing structure (22a) interposed around an active area 22b of the photocathode and the microchannel plate to establish and maintain a selected fine-dimension, precise PC-to-MCP spacing between these structures. The housing includes yieldable deformable electrical contact structure (56′) for establishing and maintaining contact with the microchannel plate, and yieldable deformable sealing structure (58) allowing axial movement of the photocathode relative to the housing structure as the tube is assembled and the axial spacing structure controls PC-to-MCP spacing. The result is that the PC-to-MCP spacing dimension of the tube is largely isolated from dimensional variabilities of the housing and is established and maintained precisely during manufacturing of the tube despite stack up of tolerances for the housing and its components.

Abstract: A diamond transmission dynode and photocathode are described which include a thin layer of a crystalline semiconductive material. The semiconductive material is preferably textured with a (100) orientation. Metallic electrodes are formed on the input and output surfaces of the semiconductive material so that a bias potential can be applied to enhance electron transport through the semiconductive material. An imaging device and a photomultiplier utilizing the aforesaid transmission dynode and/or photocathode are also described.

Abstract: An electron multiplier having an access for allowing a beam to pass is presented. The electron multiplier collects particles traveling back along the beam and is capable of collecting the particles arbitrarily close to the beam. The electron multiplier includes at least two plates having secondary electron emitting surfaces, the at least two plates being separated by a small distance. The electron multiplier has a beam access through the at least two plates. Particles enter the electron multiplier in a direction opposite that of propagation of the beam and impact a secondary electron emitting surface, thereby being captured between the top plate and the bottom plate. In some embodiments of the invention, the electron multiplier is segmented so that azimuthal distributions of the particles can be determined. In some embodiments, the electron multiplier includes a stack of electron emitting surfaces arranged so that an angular distribution of the particles can be determined.

Abstract: In an electron tube 1, a space S between a periphery part 15b of a semiconductor device 15 and a stem 11 is filled with an insulating resin 20. The insulating resin 20 functions as a reinforcing member while the electron tube 1 is assembled under high-temperature condition, thereby preventing a bump 16 from coming off a bump connection portion 19. Since the space S is only partly closed by the resin 20, the space between the semiconductor device 15 and the stem 11 is ensured a ventilability. That is, no air reservoir is formed between an electron incidence part 15a at the center of the semiconductor device 15 and the surface C of the stem 11, whereby air expanding at high temperature does not damage the electron incidence part 15a of the back-illuminated semiconductor device 15.

Abstract: A photodetecting device is characterized by comprising a photodetecting section having a photoelectric surface for emitting photoelectrons upon incidence of light, a semiconductor detection element having an electron incident surface on which the photoelectrons can be incident, and a vacuum vessel in which the photoelectric surface is arranged on one inner surface, and the semiconductor detection element is arranged on the other inner surface opposing the one surface, and cooling means for cooling a structure on the semiconductor detection element side of the vacuum vessel.

Abstract: A housing for microelectronic devices requiring an internal vacuum for operation, e.g., an image detector, is formed by tape casting and incorporates leads between interior and exterior of said housing where said leads are disposed on a facing surface of green tape layers. Adjacent green tape layers having corresponding apertures therein are stacked on a first closure member to form a resulting cavity and increased electrical isolation or channel sub-structures are achievable by forming adjacent layers with aperture dimension which vary non-monotonically. After assembly of the device within the cavity, a second closure member is sealed against an open face of the package in a vacuum environment to produce a vacuum sealed device.

Abstract: A image intensifier tube (14) includes a housing (18) carrying a photocathode (22) and a microchannel plate (24). The housing also receives axially extending fine-dimension spacing structure (22a) interposed around an active area 22b of the photocathode and the microchannel plate to establish and maintain a selected fine-dimension, precise PC-to-MCP spacing between these structures. The housing includes yieldable deformable electrical contact structure (56′) for establishing and maintaining contact with the microchannel plate, and yieldable deformable sealing structure (58) allowing axial movement of the photocathode relative to the housing structure as the tube is assembled and the axial spacing structure controls PC-to-MCP spacing. The result is that the PC-to-MCP spacing dimension of the tube is largely isolated from dimensional variabilities of the housing and is established and maintained precisely during manufacturing of the tube despite stack up of tolerances for the housing and its components.

Abstract: In a radiographic image intensifier having an input window, and a method for its production, an intermediate layer is deposited on a substrate for a luminous layer, thereby smoothing the surface of the substrate. This intermediate layer serves to smooth the surface of the substrate and is thus a good base for a uniform growth of the crystal structure of the luminous layer.

Abstract: A photocathode emitter as a source of electron beams, having an optically transmissive substrate patterned to define a protrusion, heat conducting material occupying the space surrounding the protrusion, and a photoemitter layer over the protrusion. The photoemitter is positioned on the side of the substrate opposite the surface on which the illumination is incident, and has an irradiation region at the contact with the top of the protrusion patterned on the substrate, and an emission region opposite the irradiation region, these regions being defined by the path of the illumination. The heat conducting material around the protrusion conducts heat away from this focused region of illumination on the photocathode to allow higher currents to be achieved from the photocathode and thus permits higher throughput rates in applications including electron beam lithography. In one version, the photocathode is fabricated using microfabrication techniques, to achieve a small emission spot size.

Abstract: A photocathode having a gate electrode so that modulation of the resulting electron beam is accomplished independently of the laser beam. The photocathode includes a transparent substrate, a photoemitter, and an electrically separate gate electrode surrounding an emission region of the photoemitter. The electron beam emission from the emission region is modulated by voltages supplied to the gate electrode. In addition, the gate electrode may have multiple segments that are capable of shaping the electron beam in response to voltages supplied individually to each of the multiple segments.

Abstract: To reduce phenomena of distortion in an image intensifier tube, it is planned to provide its input with a permanent test pattern. The image of the test pattern is then read in real time and a deduction is made therefrom of the correction to be made to an image transmitted and converted by this intensifier tube. To create a permanent test pattern, references are made on the intensifier tube, on its input window. As a variant, the references are produced by an auxiliary laser source that illuminates the cathode of the tube by the rear.

Abstract: The present invention assures a satisfactory adhesiveness of an input screen 13 of an X-ray image intensifier, high resolution of an output image and brightness uniformity as required, by configuring an aluminum or aluminum alloy substrate 21 so to have a concave surface with minute irregularities of the substrate material removed by burnishing, excepting gentle irregularities 21c without directivity which are caused by pressing. The gentle irregularities 21c of the substrate 21 preferably have an average length L in a range of 50 &mgr;m to 300 &mgr;m between the neighboring bottoms and an average height H in a range of 0.3 &mgr;m to 4.0 &mgr;m from peaks to bottoms. The invention improves resolution with light on the substrate surface suppressed from being scattered, and decreases image noises which are caused by the minute irregularities.

Abstract: An improved image intensifier tube has electrically operative components that include a photocathode having a photoemissive layer, a microchannel plate (MCP) having a conductive input surface and a conductive output surface, and a vacuum housing for retaining the photocathode, microchannel plate and a fiber optic inverter and screen within an evacuated environment. The fiber optic inverter has a circumferentially extending flange portion extending toward the housing to accommodate a sealing material which sealingly engages an inner surface of an output flange with the inverter flange portion to form an air impervious vacuum seal and where the output flange is supported by the fiber optic inverter flange portion. The improved intensifier includes a photocathode having a flat faceplate conductively engaging the photocathode along the entire surface of the faceplate.

Abstract: This invention relates to a transmission type electron multiplier having a high secondary electron generation efficiency and having the structure capable of detecting positions of incidence of detected light, and also to an electron tube provided therewith. The electron tube comprises a closed container, an electron source, housed in the closed container, for emitting electrons into the closed container, an anode disposed so as to face the electron source, and a transmission type electron multiplier disposed between the electron source and the anode. Particularly, the transmission type electron multiplier comprises a thin film of diamond or a material containing a principal component of diamond, and a reinforcing member for reinforcing the thin film, the reinforcing member having an aperture for exposing a part of the thin film.

Abstract: A photocathode includes a first layer of polycrystalline diamond or a material mainly composed of polycrystalline diamond. The first layer of polycrystalline diamond may be terminated with hydrogen, or oxygen, and a second layer of an alkali metal or compound of an alkali metal, may be provided on the first layer of polycrystalline diamond whose surface is terminated with hydrogen or oxygen. The photocathode can be use for both reflection and transmission electron tubes and can yield a quantum efficiency higher than that in a monocrystal diamond thin film.

Abstract: An electron source includes a negative electron affinity photocathode on a light-transmissive substrate and a light beam generator for directing a light beam through the substrate at the photocathode for exciting electrons into the conduction band. The photocathode has at least one active area for emission of electrons with dimensions of less than about two micrometers. The electron source further includes electron optics for forming the electrons into an electron beam and a vacuum enclosure for maintaining the photocathode at high vacuum. The photocathode is patterned to define emission areas. A patterned mask may be located on the emission surface of the active layer, may be buried within the active layer or may be located between the active layer and the substrate.

Abstract: An electron beam source includes a cathode having an electron emission surface including an active area for emission of electrons and a cathode shield assembly including a conductive shield disposed in proximity to the electron emission surface of the cathode. The shield has an opening aligned with the active area. The electron beam source further includes a device for stimulating emission of electrons from the active area of the cathode, electron optics for forming the electrons into an electron beam and a vacuum enclosure for maintaining the cathode at high vacuum. The cathode may be a negative electron affinity photocathode formed on a light-transmissive substrate. The shield protects non-emitting areas of the emission surface from contamination and inhibits cathode materials from contaminating components of the electron beam source. The cathode may be moved relative to the opening in the shield so as to align an new active area with the opening.

Abstract: An electron source includes a negative electron affinity photocathode on a light-transmissive substrate and a light beam generator for directing a light beam through the substrate at the photocathode for exciting electrons into the conduction band. The photocathode has at least one active area for emission of electrons with dimensions of less than about two micrometers. The electron source further includes electron optics for forming the electrons into an electron beam and a vacuum enclosure for maintaining the photocathode at high vacuum. In one embodiment, the active emission area of the photocathode is defined by the light beam that is incident on the photocathode. In another embodiment, the active emission area of the photocathode is predefined by surface modification of the photocathode. The source provides very high brightness from an ultra-small active emission area of the photocathode.

Abstract: This invention relates to an improvement of a reflection mode alkali photocathode which relies on controlling a deposition weight of antimony. The reflection mode alkali photocathode according to this invention includes a thin layer of antimony directly deposited on a base substrate and activated by alkali metals. The thin film of antimony is deposited in a thickness of below 100 .mu.g/cm.sup.2. This reflection mode photocathode is suitably usable in photomultipliers. As the base substrate, nickel, aluminium and stainless, etc. are used. As the alkali metals, cesium, potassium, sodium and rubidium are usable.

Abstract: This invention relates to an improvement of a reflection mode alkali photocathode which relies on controlling a deposition weight of antimony. The reflection mode alkali photocathode according to this invention includes a thin layer of antimony directly deposited on a base substrate and activated by alkali metals. The thin film of antimony is deposited in a thickness of below 100 .mu.g/cm.sup.2. This reflection mode photocathode is suitably usable in photomultipliers. As the base substrate, nickel, aluminium and stainless, etc. are used. As the alkali metals, cesium, potassium, sodium and rubidium are usable.

Abstract: A segmented photomultiplier tube having an electrode which, in its higher part acts as a focusing electrode for distributing photo-electrons on both sides of an axial plane, while in its lower part forming a collection cage, the photo-electrons undergo a first multiplication at the portions of the lateral walls, which are folded towards the axial plane. Apertures in a median plate of the electrode are covered by a highly transparent grid. The electrode is completed by a central partition which extends along the median plate just to the proximity of an input dynode of a laminated multiplier. A bar having a small cross-section may be provided, centered on the axial plane and receiving a potential near the potential across the photocathode. A plurality of these tubes can be arranged in a mosaic pattern for mapping luminous events.

Abstract: In order to increase the sensitivity of an image intensifier tube, the efficiency with which an electron image is formed from radiation of a first wavelength is increased. Radiation of the first wavelength is converted into radiation of a second wavelength by means of a conversion screen provided with a scintillation layer, and radiation of the second wavelength releases electrons from a photocathode which is sensitive to the second wavelength. Loss of radiation of a second wavelength, incurred because a part of this radiation does not reach the photocathode, is reduced. Radiation of the second wavelength which is not emitted in the direction of the photocathode is recaptured by providing the conversion screen with a metallic reflecting intermediate layer.

Abstract: A high performance reflection type photocathode for use in a photomultiplier tube is formed by sequentially depositing three layers on a substrate made of nickel. The first layer is made of either one of chromium, manganese and magnesium as a major component and is deposited over the substrate. The second layer is made of aluminum as a major component and is deposited over the first layer. The third layer is made of antimony and at least one kind of alkaline metals and is deposited over the second layer.

Abstract: High quantum efficiency (.gtoreq.5%) ultrafast (.ltoreq.100 picosecond) and broad band (30 KeV to 80 KeV for medical application) X-ray photo-electron cathode, high gain X-ray real time image intensifier and portable low intensity real time projection type X-ray imagescope use new vacuum photo-electron devices. A new type X-ray photo-electron cathode has a specially designed alkali halide electron emission layer that makes possible high quantum efficiency, high speed and broad band X-ray photon detection. An X-ray photo-electron cathode followed by a direct coupled micro channel plate and an output phosphor display screen form a new type panel shaped direct view X-ray intensifier tube which can have both high spatial resolution (.gtoreq.10 lp/mm) and high gain (.gtoreq.10.sup.4). The thickness of this panel shaped disc X-ray intensifier can be less than 1 cm.

Abstract: An image pick-up apparatus is disclosed which includes a target portion having a photoconductive film on a substrate and a target electrode and reads video information converted into an electric signal in the photoconductive film by an electron beam. An insulating region is provided for the target portion such that carrier generated in an ineffective scanned region (a target region corresponding to an area not scanned by the electron beam) does not appear on a surface of the target portion.

Abstract: A vacuum-tight envelope (601) having a terminal element (610) bearing the envelope's output window. An output screen (605) is glued to the inner face of the output window by a first glue (608) having the same refractive index as the output window. The envelope's terminal element is made unitary with a (611) of the envelope by vacuum-tight mounting (609). An optional anti-reflection coating (674) may be deposited directly onto the external face of the output window.

Abstract: An image intensifier tube having a photocathode, a microchannel plate and an anode. The anode includes a lens element with a phosphor screen deposited thereon as an output window. The lens element may take the form of either a plano-convex or plano-concave element and has either a spheric or aspheric curved surface. In a modified version a plano glass element is affixed to the plano surface of the lens element. Methods of forming the tube with the lens element are at the time the finished tube is assembled in the intensifier device or at the time the tube is constructed.

Abstract: An aluminum substrate which supports a scintillator transforms X-rays into visible or nearly visible light radiation which is converted into a flux of electrons by means of a photocathode. The flux produces a visible image on an exit screen through electro-optical means. A layer which absorbs the light radiation emitted by the scintillator in the direction of the aluminium substrate is inserted between the aluminium substrate and the scintillator, the absorbing layer consisting of a material chosen from the following materials: titanium nitride, cadmium sulphide, (Cu, OhI.sub.2). A layer having a low optical index can be inserted between the scintillator and the photocathode. A chemical barrier may also be inserted between the scintillator and the photocathode. An electrically conductive and optically transparent layer can be inserted between the photocathode and the chemical barrier.

Abstract: Disclosed is a method for the fabrication of an X-ray image intensifier tube. Before being introduced into the X-ray image intensifier, one of all the electrodes are entirely or partially covered with a layer of an orgainc polymer which is an electronic conductor of electricity and which has the property of reacting chemically with the alkaline metals deposited on the electrodes. Thus, the spurious illumination of the observation screen, due to the alkaline metals deposited on the electrodes during the preparation of the photocathode, is eliminated.

Abstract: In an image intensifier tube the input screen has a profile which is determined by a higher degree polynomial of which the constant term and the first order term are both zero. As a result of this the profile shows no local inhomogeneities and the profile may be adapted to an optical imaging by the electron-optical system of the photocathode on the output screen.

Abstract: An ionic bombardment barrier layer is provided for vacuum tube, said layer being formed of a stable compound of nitrogen and silicon. It is deposited by vapor phase chemical reaction activated by low temperature plasma. It finds an application in light image intensifier tubes.

Abstract: Shown is an integral two-stage vacuum tube with means for efficient optical coupling of the light from an output screen of the first stage into the photocathode of the second stage.

Abstract: A shielded faceplate for use in an image intensifier having a photocathode which comprises an inner core of glass transparent to light to which the photocathode is sensitive and an outer shielding region of glass which absorbs light to which the photocathode is sensitive. The outer shielding region surrounds and is adjacent to the inner core. The inner core has a transverse dimension which decreases along its length, the transverse dimension being smallest at the photocathode surface. The shielded faceplate is manufactured by arranging in a mold to which glass does not bond a first type of glass transparent to light to which the photocathode is sensitive and a second type of glass which absorbs light to which the photocathode is sensitive, heating the glass members so that they fuse to produce a block having an inner core of the first type of glass and an outer region of the second type of glass and removing the block from the mold.