Abstract: A field emission cathode device and method for forming a field emission cathode device involve a cathode element having a field emission surface disposed in spaced-apart relation to a gate electrode element so as to define a gap between the field emission surface and the gate electrode element. The gate electrode element extends laterally between opposing anchored ends. The gate electrode element is arranged to deform away from the field emission surface in response to heat, so as to increase the gap between the field emission surface and the gate electrode element.

Abstract: Electronic devices with displays are configured to provide a gamma correction signal to each source driver chip driving the display. The gamma correction signal is supplied by a gamma application circuit coupled to each source driver chip. The gamma application circuit includes a switching amplifier configured to output a switching waveform and a filter to input the switching waveform and output the gamma correction signal to an input of each source driver chip. The switching amplifier functions as a switching power supply having improved power efficiency compared to conventional gamma application circuits.

Abstract: A method of adjusting a stigmator in a particle beam apparatus comprises directing a particle beam onto a sample wherein the particle beam traverses a quadrupole field 37 generated by energizing at least four field generators of the stigmator; acquiring first and second images of the sample at different field strengths of the quadrupole field while energizing the at least four field generators according to a first setting of a plurality of settings; acquiring third and fourth images of the sample at different field strengths of the quadrupole field 37 while energizing the at least four field generators according to a second setting of the plurality of settings; determining a plurality of image displacements based on the first, second, third and fourth images; determining an optimum setting of the at least four field generators based on the plurality of image displacements and the plurality of settings.

Abstract: A method of forming a current diffusion layer is provided that comprises providing an epitaxial wafer. The method further comprises depositing ITO source material on the epitaxial wafer to form a base ITO layer by a direct current electron gun and depositing ZnO source material, during simultaneous deposition of the ITO source material, on the base ITO layer to form a ZnO doped ITO layer by a pulse current electron gun. The ZnO source material is deposited at a deposition rate higher than the rate at which the ITO source material is deposited. Generation and termination of current may be controlled by adjusting a duty cycle of pulse current provided by the pulse current electron gun and result in discontinuous deposition of the ZnO source material. The method further comprises depositing the ITO source material on the ZnO doped ITO layer to cover the ZnO doped ITO layer and form a finished ITO layer.

Abstract: A current control device is a current control device which supplies current to a load device by controlling a current source including a first electric appliance and a voltage source including a second electric appliance. The current control device includes: an obtaining unit which obtains information indicating non-linear components included in load current that is current supplied to the load device; a determining unit which determines a first current that includes the non-linear components; and a notifying unit which notifies the current source of a command value for causing the current source to output the first current to cause the current source to output the first current.

Abstract: A field emission device is configured as a heat engine. Different embodiments of the heat engine may have different configurations that may include a cathode, gate, suppressor, and anode arranged in different ways according to a particular embodiment. Different embodiments of the heat engine may also incorporate different materials in and/or proximate to the cathode, gate, suppressor, and anode.

Abstract: A field emission device is configured as a heat engine with an AC output.

Abstract: Field emission devices are configured in addressable arrays.

Abstract: A photocathode system includes a plurality of photocathodes, and at least one combining device. The photocathodes have individually adjustable voltages, and each photocathode generates an individual electron bunch at an emission period. The combining device combines the individual electron bunches, generated at each emission period, into a combined bunch along a combined axis. The timing of the individual electron bunches is independently adjustable, so that an electron bunch with a lower energy arrives at the combined axis earlier in time compared to another electron bunch with a higher energy, thereby allowing the combined beam of electron bunches to be longitudinally compressed. The photocathodes may be distributed along a 1D column, or a 2D array, or a 3D array, or any arbitrary configuration. A linac is located near a longitudinal focusing point to boost beam energy and therefore freeze bunch length and emittance.

Abstract: A field emission device is configured as a heat engine, wherein the configuration of the heat engine is variable as a function of time.

Abstract: A field emission device is configured as a heat engine with an AC output.

Abstract: System that focuses electron beams in an electro-static area to a laminar flow of electrons with uniform distribution of current density and extraordinary demagnification includes a housing having a first interior portion and a second interior portion electrically insulated from the first interior portion. The second interior portion has an electric field-free space. An electrode system is disposed in the first interior portion and includes a cathode assembly and at least one anode assembly. The cathode assembly generates an electron beam that passes through each anode assembly and then into the electric field-free space in the second interior portion. A position of a crossover point on a longitudinal axis maybe regulated by varying dimensions of a substantially cylindrical portion of the anode assembly and a substantially cylindrical portion of a near-cathode electrode assembly.

Abstract: An electron cooling system and method for increasing the phase space intensity and overall intensity of ion beams in multiple overlap regions, including a vacuum chamber to allow a single electron beam to be merged and separated with multiple ion beams, an electron supply device including a cathode to generate the electron beam, an electron collector device including a collection plate to collect the electron beam, multiple magnetic field generation devices to guide the electrons on their desired trajectories, and multiple electrodes to set the velocity of the electron beam independently in each overlap region. By overlapping the electron and ion beams, thermal energy is transferred from the ion beams to the electron beam, which allows an increase in the phase space density and overall density of the ion beams.

Abstract: A particle beam, segmented electron gun, segmented electron beam and electron collector system and method to achieve low power loss, segmented current control, and segmented energy control in electron beams, including a vacuum chamber to provide a region substantially free of background gas and allow for electron transport, an electron supply device including a segmented cathode to generate the segmented electron beam, an electrode with a grid conducting structure located in front of the segmented cathode and biased with respect to the segmented cathode in order to accelerate electrons away from the segmented cathode and control the current and energy of each electron beam segment, magnetic field production devices such as solenoidal and torroidal wire windings and permanent magnet material to produce magnetic fields to guide the segmented electron beam and to contain neutralizing-background-ions and an electron collector device including electrodes with a grid conducting structure and outer conducting shell

Abstract: An electron emitting element of the present invention includes: an electrode substrate; a thin-film electrode; and an electron acceleration layer sandwiched between the electrode substrate and the thin-film electrode, the electron acceleration layer including (1) conductive fine particles, (ii) insulating fine particles having an average particle diameter greater than an average particle diameter of the conductive fine particles, and (iii) a crystalline electron transport agent. The crystalline electron transport agent is crystallized in the acceleration layer.

Abstract: An apparatus and method of modulating an electron beam to induce a high degree of spatial bunching uses multiple control grids located in close proximity to an electron-emitting cathode. An RF field couples to the electron beam in the cathode-grid gap to induce velocity modulation. The electron beam then propagates through a first control grid, allowing the velocity modulation to induce spatial bunching. The electron beam then traverses a gap between the first grid and a second control grid and interacts with the RF field to induce further bunching of the beam. Simulations show that bunching factors of 50:1 may be achieved.

Abstract: An active electronically steered cathode (AESC) applies one or more electromagnetic modes to an input cavity, similar to that used in an inductive output tube. The structure and superposition of these modes creates local electric field maxima, causing the electron emission site or sites to move or be distributed across the surface of the cathode. Changing the amplitude, phase, or frequency of the modes provides time-variable control of the electric field profile, thereby generating electronically steered electron beams. One embodiment employs a pair of orthogonal TM modes driven out of phase, causing the electric field maximum to rotate around an annular cathode, producing a helical beam. Slots in the control grid may be used to segment the helical beam into discrete bunches to provide additional density modulation.

Abstract: An electron gun used with a multi-media monitor with a low cathode voltage and improved focusing performance. The electron gun, which includes a cathode, a control electrode, a screen electrode, and a plurality of focusing electrodes to focus and accelerate an electron beam, is designed to satisfy the condition that a value of ? is greater than or equal to 0.222 or a value of k is greater than or equal to 0.11, where ?=T1/D, k=T1/L, T1 denotes a thickness of the control electrode, D denotes a diameter of an electron beam aperture of the control electrode, and L denotes the distance between a beam-entering surface of the control electrode and a beam-emitting surface of the screen electrode.

Abstract: A low voltage Einzel gun design maximizes the size of the second main lens to reduce spherical aberrations thereby reducing spot-size and improving focus quality. The gun's final accelerator electrode is formed as an internal conductive coating on the neck, which is connected to anode potential through an anode button. The jumper between the final and second accelerator electrodes is removed and the second accelerator electrode is connected through the high voltage stem pin to an external potential. Connection of the high voltage stem pin to anode potential defines an Einzel gun. The focus electrode is now connected to one of the low voltage stem pins. In a high voltage Einzel gun, connecting the second accelerator electrode and focus electrode to the high voltage and a low voltage stem pin, respectively, would cause arcing between the pins.

Abstract: Provided is an electron beam apparatus which can limit the influence of aberration of a secondary optical system without the need for providing a diaphragm in the optical system, which comprises a multi-emitter type thermal cathode that reduces shot noise, and which has a multi-emitter and a Wehnelt electrode placed in parallel with each other to permit easy and accurate alignment therebetween. In one embodiment, electron beams emitted from an electron beam source are irradiated to a first aperture plate having a plurality of apertures to generate a plurality of primary electron beams which are directed onto a sample. Secondary electrons emitted from the sample are separated from a primary optical system, directed to a secondary optical system as groups of secondary electrons, and focused on a detector, so that the detector outputs detection signals of the secondary electron beams. A second aperture plate having a plurality of apertures is provided in front of the incident plane of the detector.

Abstract: The present invention provides a high-resolution color picture tube device with a decreased beam spot diameter. The color picture tube device has an electron gun including cathodes, a control electrode, an accelerating electrode, a G3 electrode, a first focusing electrode, a second focusing electrode, and a final accelerating electrode that are arranged in this order. A voltage applied to the G3 electrode is obtained by dividing with a resistor a voltage applied to the final accelerating electrode, and when an electron beam is a non-deflection state, a relationship represented as Va>Vg3>Vfoc2 is satisfied where Va, Vg3, and Vfoc2 denote voltages respectively applied to the final accelerating electrode, the G3 electrode and the second focusing electrode. Thereby, the G3 electrode is applied with a high voltage independently for forming a prefocus lens.

Abstract: A bonded, walk-off compensated crystal, for use with optical equipment, and methods of making optical components including same.

Abstract: The screen electrode in an electron gun for use in a cathode ray tube has multi-stage apertures such that the entrance area of an aperture is larger than the exit area. This has an effect of smaller screen electrode apertures with a result of increased pre-focusing of electron beams passing through the apertures. Thus, increased pre-focusing reduces the beam incident angle to the main lens. A smaller beam incident angle generates less spherical aberration in the main lens.

Abstract: An electron gun assembly for a CRT includes three cathode electrodes, a control electrode, an electron-stream extractor electrode, a focusing electrode, and an anode electrode. The electron-stream extractor electrode includes first, second, and third holes, each of which allows one of the three streams of the electrons to pass through. The focusing electrode includes a flat portion having fourth, fifth, and sixth holes, each of which allows one of the three streams of the electrons to pass through. The first, second, and third holes are arranged in the in-line direction. Each of the fourth and sixth holes includes a substantially rectangular opening and a substantially semicircular opening connected to each other. One side of the substantially rectangular opening is connected to a straight line segment of the substantially semicircular opening, and the substantially rectangular opening is disposed outside while the substantially semicircular opening is disposed inside.

Abstract: A multi-beam color index cathode ray tube (CRT) includes vertically spaced, horizontal phosphor stripes on the inner surface of its display screen. The parallel phosphor bands are arranged in groups of three, with each phosphor stripe in a group providing a respective one of the three primary colors of red, green and blue. An electron gun directs three electron beams onto the display screen, with the three electron beams deflected over the display screen in unison in a raster pattern. The three electron beams are focused in the form of three spots on the display screen, with each spot coincident with a respective horizontal phosphor stripe of a given color. The intensity of each electron beam is independently modulated as it sweeps across the width of the display screen by a respective color video signal in accordance with the displayed image.

Abstract: Disclosed is a power-supplying device for an electron gun in a color display tube (CDT) provided with an fly back transformer (FBT) having a focus voltage output terminal and an acceleration voltage output terminal, further having a power supplying part supplying a predetermined reference voltage; a focus voltage detection part detecting a focus voltage of the focus voltage output terminal; and a focus voltage boost part boosting the focus voltage of the focus voltage output terminal in case that the focus voltage detected by the focus voltage detection part is lower than the reference voltage of the power supplying part. With this configuration, it is possible to recover the voltage of the focus voltage output terminal dropped according to the grid discharging of the electron gun in the color display tube to the normal voltage.

Abstract: An electron gun for a color CRT includes a triode including cathodes for emitting electron beams, a control electrode, and a screen electrode, at least two focusing electrodes on the same axis of the triode portion for forming a quadrupole lens, and a final focusing electrode forming a large diameter lens with the focusing electrodes and through which three electron beams commonly pass. The electron gun includes a correction unit producing a correction force acting on the three electron beams and that is larger for two side electron beams than for a central electron beam of the three electron beams when a dynamic voltage, synchronized with a deflection signal, is applied to at least one of the focusing electrodes for forming the quadrupole lens.

Abstract: A colour display device (19) is disclosed having an improved focus performance. In state-of-the-art colour display tubes, a static voltage is applied to the focusing electrode (23). This means that only one focus voltage is available for the entire range of beam currents. In general, due to the fact that the diameter of the electron beams (7,8,9) increases as the beam current increases, the focus voltage is a function of this beam current, which itself is determined by the cathode voltage. In this invention, a colour display device (19) is disclosed in which the voltage on the focusing electrode (23) is changed as a function of the cathode voltages, thereby significantly improving the focus performance.

Abstract: A high-speed field emission vacuum switching device comprises a cathode tip formed on a substrate, an extraction grid close to the cathode tip, and a modulator grid spaced from the cathode tip by a dielectric layer. The grids have apertures aligned with the cathode tip. An anode is spaced from the modulator grid by a dielectric layer. By use of the modulator grid, a substantial improvement in high-frequency switching performance can be achieved. A collector grid may be provided between the extraction grid and the modulator grid, and a cut-off grid may be disposed between the modulator and collector grids.

Abstract: A color picture tube of the present invention comprises three in-line cathodes (1a, 1b, 1c) aligned in the horizontal direction, a first focussing electrode (4) supplied with a focus voltage, a second focussing electrode (5) supplied with a dynamic voltage that changes in accordance with a deflection angle of the electron beams, a final accelerating electrode (7) supplied with an anode voltage, an intermediate auxiliary electrode (6) arranged between the second focussing electrode (5) and the final accelerating electrode (7). The intermediate auxiliary electrode (6) is supplied with a voltage between the voltage of the second focussing electrode (5) and the anode voltage. A non-axisymmetric electrostatic lens for focussing electron beams in the horizontal direction and diverging them in the vertical direction is formed between the first and second focussing electrodes (5, 6). The power of the non-axisymmetric electrostatic lens changes in accordance with a deflection angle of the electron beam.

Abstract: An electron gun assembly includes a plurality of cathodes arranged in an in-line direction, at least first through fourth grids having electron beam passing holes arranged in an in-line direction, and an insulation support for sandwiching the cathodes and the grids between and fixing the cathodes and the grids from a direction perpendicular to the in-line direction. The second grid and the fourth grid are supplied with substantially the same low potential, the third grid is supplied with a potential higher than the potential of the fourth grid, and the second grid is fixed to the insulation support on a side of the third grid. The third grid has a cup-shaped electrode on a side of the second grid, the cup-shaped electrode including a plane portion having electron beam passing holes, an opening portion, and planting portions planted in the insulation support.

Abstract: An internal resistor within a color cathode ray tube (CRT) is connected to a voltage source and is coupled across a G4 grid and a G6 grid of the CRT's multi-grid quadrupole (QPF) electron gun. De-coupling the G4 grid from the G2 grid in the electron gun's prefocus lens and operating the G4 grid at a higher voltage as used in the gun's high voltage main focus lens moves the equivalent lens of the prefocus and main focus lenses toward the CRT's display screen and reduces electron beam magnification and spot size for improved video image definition and focusing.

Abstract: An improved inline electron gun includes a plurality of electrodes spaced from three cathodes in the direction of a longitudinal axis of the gun. The electrodes form at least a beam forming region and a main focus lens in the paths of three electron beams, a center beam and two side beams. Each of the electrodes includes three inline apertures therein for passage of the three electron beams. The beam forming region includes the cathodes and three consecutive electrodes, a G1 electrode, a G2 electrode and a G3 electrode. The improvement comprises the G2 electrode having two linear projections on either side of the inline apertures therein. The projections parallel the inline direction of the apertures protrude in a direction parallel to the longitudinal axis, past the apertured portion of the G3 electrode in overlapping relationship therewith. On the side of the G3 electrode facing the G2 electrode, the G3 electrode has two linear channels therein on either side of the inline apertures therein.

Abstract: A color cathode ray tube includes an in-line electron gun having a main lens with recessed apertures. The main lens is formed by two electrodes. These electrodes have outer edges and recessed apertures which allow passage of three in-line electron beams and which are arranged at a distance d1 and d2, respectively, from the outer edges. The outermost apertures are asymmetric. The difference d1-d2 and the asymmetry of the outermost apertures is such that both the beam displacement and the core haze asymmetry are minimal.

Abstract: An electric power source assembly supplies the focusing electrodes of a color cathode ray tube. Such a color cathode ray tube normally includes three electron guns arranged in a line transverse to their beam path. The focusing voltages supplied the focusing electrodes associated with the three guns are independently adjusted to compensate for beam distortion caused by positional differences in gun location. The D.C. and A.C. voltage to the static and or dynamic electrodes is independently controlled to improve beam focus of each individual gun.

Abstract: An in-line color picture tube compensates for the distortion in the illuminated spot at the peripheral portion of the screen in a horizontally oblong shape. In particular, with an increase in the beam diameter under large current, or flattening of the panel or increase in the deflection angle, the beam distorted easily. However, such distortion is made to be small by providing a quadrupole lens with strong power. The in-line color picture tube has an electron gun comprising three cathodes that are in-line arranged in horizontal direction, a control electrode, an accelerating electrode and a focusing electrode system. The focusing electrode system comprises a couple of focusing electrodes having the facing portion on which non-circular beam through holes are provided. A predetermined focus voltage is applied to the first focusing electrode. A voltage changing in accordance with a deflection angle of the beam is applied to the second focusing electrode.

Abstract: The triode portion of an electron gun includes a cathode having an electron emitting material layer and a control electrode in which a through hole portion having a plurality of through holes for passing an electron beam is formed on a surface facing the electron emitting material layer so that the life span of the cathode can be prolonged.

Abstract: Color cathode ray tube (1) device having an electron gun (6) of the in-line type for generating three electron beams (7,8,9), a display screen (10) and deflection coils (11) for scanning the electron beams over the display screen. The electron gun includes a main lens part for focusing the electron beams on the display screen, the main lens part comprising main lens electrodes (26, 27) having apertures for passing of the electron beams, at least one of said main lens electrodes comprising two sub-electrodes (26a, 26b) adjacent to each other, each of the sub-electrodes having a central (311, 321) and two outer apertures (312, 322, 313, 323), whereby in operation between the adjacent sub-electrodes an astigmatic quadrupole field is generated. For the central apertures of the sub-electrodes it holds:xQa.ltoreq.xQband for the two outer apertures of the sub-electrodes it holds:yQa.ltoreq.yQb.

Abstract: An electron gun for a cathode ray tube includes an accelerating electrode to be supplied with a maximum voltage, a focus electrode disposed adjacent to but spaced from the accelerating electrode, and a focus-corrective electrode adjacent to but spaced from the focus electrode. The accelerating electrode and the focus electrode form a first electron lens for focusing the electron beams stronger in a horizontal direction than in a vertical direction, and the focus-corrective electrode is configured so as to form a second electron lens by application thereto of a voltage lower than a voltage applied to the focus electrode in cooperation with the focus electrode for focusing the electron beams stronger in the vertical direction than in the horizontal direction, and is adapted to be supplied with a voltage increasing with increasing deflection of the electron beams but lower than the voltage applied to the focus electrode.

Abstract: In an electron gun, and a color cathode-ray tube and an image display device using the electron gun, each of two pairs of convergence electrodes is disposed in a focusing electrode for focusing three electron beams in a manner to pass the respective side beam of the three electron beams. Since an alternating current voltage synchronized with a deflection current is superposed to one of each pair of the convergence electrodes, such forces are exerted to the side beams as to separate the side beams from each other in the vicinity of the peripheral edge of a screen having a fluorescent body, so that the converging point of the electron beams is positioned on the screen. The focusing function of a main electron lens is weakened in the vicinity of the peripheral edge of the screen, whereby the electron beams are correctly focused.

Abstract: An electron gun having an improved circuitry for driving the electron gun, which includes a cathode ray tube accommodating at least a cathode, a control electrode, a first acceleration electrode, a convergence electrode comprising first and second grids sandwiching at least a quadrupole lens and a second acceleration electrode. The circuitry is provided with a voltage divider having first and second ends which are electrically connected between the control electrode and the first grid respectively. The voltage divider being electrically connected to at least a dc power supply to apply a bias between the first and second ends of the voltage divider so that the first and second ends of the voltage divider have first and second voltage levels which are different by the bias from each other. The voltage divider has a voltage dividing point between the first and second ends.

Abstract: The present invention is directed to a transmission type flat cathode ray tube in which a flat glass tube envelope (15) is formed of a triple structure having a screen panel (11), a back panel (12) and a funnel portion (14) having a neck portion (13). A carbon film (24) to which an anode voltage is applied is formed on the inner surface of the back panel 12 in an opposing relation to a phosphor screen (19) of the screen panel (11). Thus, the occurrence of a pseudo signal in the transmission type flat cathode ray tube can be avoided.

Abstract: A color cathode ray tube includes an electron beam generating source, a first accelerating electrode, a focus electrode, and a second accelerating electrode, for focusing an electron beam onto the phosphor screen. The length of the focus electrode is equal to or larger than two times the diameter of the main lens, and the highest voltage is applied on the first accelerating electrode and the second accelerating electrode, and a voltage lower than the highest voltage is applied on the focus electrode, and the length of the first accelerating electrode is within the range from about 0.4 to 2 times the diameter of the electron beam passage aperture formed in the surface of the first accelerating electrode on the side of the electron beam generating source.

Abstract: A cathode ray tube suitable for use as a visual display includes two or more electron guns. The beams from the electron guns are aligned vertically so that a single horizontal scan of the guns produces two rows of pixels on the front face of the tube. This allows twice as much data to be painted on the display screen without increasing the scan rate of the electron guns. Each of the guns may be a single beam gun, for monochrome displays, or each may be a triple-element gun for RGB displays.

Abstract: A color cathode ray tube includes three in-line cathodes, a control electrode, an accelerating electrode, a first focusing electrode member, a second focusing electrode member, an anode, and a phosphor surface disposed in the order listed after the three in-line cathodes along a tube axis, and a fixed resistor disposed inside the color cathode ray tube. The fixed resistor is coupled between the anode and ground, and has a focusing power supply terminal. The three in-line cathodes emit respective electron beams which pass through the control electrode, the accelerating electrode, the first focusing electrode member, the second focusing electrode member, and the anode and land on the phosphor surface. The first focusing electrode member receives a constant focusing voltage from the focusing power supply terminal of the fixed resistor, and the second focusing electrode member receives a dynamic focusing voltage which varies in accordance with a deflection angle of the electron beams.

Abstract: A cathode ray tube having an electron gun for relatively low beam currents (less than 1 mA) is shown. The electron gun has a G1 and a G2 electrode. The voltage difference between these electrodes is more than 800 Volt and the electrical field strength E.sub.12 between said electrodes is more than 4 keV/mm. An improvement in spot size is thereby obtained.

Abstract: An electron gun for a cathode-ray tube has, in addition to its main lens, a triode with first and second grids as control electrodes. The thickness of the second grid, and the separation between the first and second grids, is at most one-half the diameter of the beam aperture in the second grid. These dimensions lead to formation of a prefocus lens with no concave lens component, hence with no beam diverging effect. The resulting triode aberration corrects spherical aberration in the main lens, so that the size of the beam spot focused on the screen has little tendency to increase with increasing beam current.

Abstract: A multi-beam electron gun for use in a monochrome cathode ray tube (CRT) such as used in a black and white television receiver, a projection television receiver, or a computer monitor includes G1 control and G2 screen grids each having a plurality of vertically aligned apertures for forming electron beams which are deflected in unison across the CRT's display screen to simultaneously trace a plurality of vertically spaced, horizontal scan lines with each display screen sweep. The electron beams are deflected across the screen in a raster-like manner with each beam containing video information for each adjacent scan line. The G1 control grid includes a plurality of discrete conductive portions each including a respective beam passing aperture and each coupled to a respective video signal source, with the video signal sources including memory for storing video signal information for subsequent display.

Abstract: An electron gun for a color cathode ray tube includes a cathode, a control electrode and a screen electrode constituting a prepositioned triode. First, second, third and fourth focus electrodes form two pre-focus lenses and a final accelerating electrode positioned adjacent to the fourth focus electrode forms a main focus lens. The first pre-focus lens is synchronous with a deflection signal. Variation of the focussing intensity of the main focus lens is compensated for by the first pre-focus lens.

Abstract: A system for controlling the shape of a charged particle beam. The particle beam is emitted from a source (58) of the said particles. Said source is associated with a collecting electrode which collects the particles. The system comprises at least one resistive zone (56) and at least two control electrodes (52, 54). The resistive zone and the control electrodes are arranged substantially at the same level as the source. The control electrodes are also placed on either side of the resistive zone and serve to polarize the latter. The electrical resistance profile of the resistive zone is chosen in such a way that it has the potential distribution so that it is possible to obtain the desired shape of the beam from the source when the control electrodes are appropriately polarized.