Abstract: Disclosed is a method, receiver, multi-receiver device, system and computer readable medium for configuring a receiver to perform multi-transmitter channel estimation for a time-varying channel. In one aspect, the method includes: wirelessly receiving at least two frames, each frame including a block of training symbols received at different points in time for a time-varying channel; estimating, for each block at a block location, a first channel coefficient of the time-varying channel, wherein the block location is the same for each block; and interpolating or extrapolating a plurality of second channel coefficients for the respective training symbols of each block based on the respective first channel coefficient.

Abstract: An individual beam detector for multiple beams includes a thin film in which a passage hole smaller than a pitch between beams of multiple beams and larger than the diameter of a beam is formed and through which the multiple beams can penetrate, a support base to support the thin film in which an opening is formed under the region including the passage hole, and the width size of the opening is formed to have a temperature of the periphery of the passage hole higher than an evaporation temperature of impurities adhering to the periphery in the case that the thin film is irradiated with the multiple beams, and a sensor arranged, at the position away from the thin film by a distance based on which a detection target beam having passed the passage hole can be detected by the sensor as a detection value with contrast discernible.

Abstract: The present invention discloses various improvements to multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) wireless communication systems. In one aspect there is disclosed an efficient and accurate channel estimation method and system using locally consecutive pilot sub-carriers. In another aspect there is disclosed an efficient channel feedback method and system by applying a discrete cosine transform to channel coefficients. In another aspect there is disclosed an efficient method and system to calculate a part of the channel inverse by interpolation. These aspects can be used in combination to improve the MU-MIMO-OFDM system.

Abstract: An individual beam detector for multiple beams includes a thin film in which a passage hole smaller than a pitch between beams of multiple beams and larger than the diameter of a beam is formed and through which the multiple beams can penetrate, a support base to support the thin film in which an opening is formed under the region including the passage hole, and the width size of the opening is formed to have a temperature of the periphery of the passage hole higher than an evaporation temperature of impurities adhering to the periphery in the case that the thin film is irradiated with the multiple beams, and a sensor arranged, at the position away from the thin film by a distance based on which a detection target beam having passed the passage hole can be detected by the sensor as a detection value with contrast discernible.

Abstract: Disclosed is a method, receiver, multi-receiver device, system and computer readable medium for configuring a receiver to perform multi-transmitter channel estimation for a time-varying channel. In one aspect, the method includes: wirelessly receiving at least two frames, each frame including a block of training symbols received at different points in time for a time-varying channel; estimating, for each block at a block location, a first channel coefficient of the time-varying channel, wherein the block location is the same for each block; and interpolating or extrapolating a plurality of second channel coefficients for the respective training symbols of each block based on the respective first channel coefficient.

Abstract: The present invention discloses various improvements to multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) wireless communication systems. In one aspect there is disclosed an efficient and accurate channel estimation method and system using locally consecutive pilot sub-carriers. In another aspect there is disclosed an efficient channel feedback method and system by applying a discrete cosine transform to channel coefficients. In another aspect there is disclosed an efficient method and system to calculate a part of the channel inverse by interpolation. These aspects can be used in combination to improve the MU-MIMO-OFDM system.

Abstract: A device which employs an electron beam, for performing a desired function, includes an electron gun for generating the electron beam. The electron gun includes a barrel shaped rotatable structure having a plurality of annularly disposed electron sources. A curvature of a surface portion of the rotatable structure is shaped to optimize electric field concentrations. The rotatable structure further includes end portion protrusions.

Abstract: A clamping flexure for use in a vacuum employs a spring-loaded shaft that pulls an object being supported against a support piece, including a mechanism, passing through the vacuum vessel, for releasing the spring tension during adjustment, the shaft being sufficiently compliant that restoring force after adjustment is less than a threshold value so that displacement of the shaft does not impress a force on the object being supported that returns it toward its position before adjustment.

Abstract: A clamping flexure for use in a vacuum employs a spring-loaded shaft that pulls an object being supported against a support piece, including a mechanism, passing through the vacuum vessel, for releasing the spring tension during adjustment, the shaft being sufficiently compliant that restoring force after adjustment is less than a threshold value so that displacement of the shaft does not impress a force on the object being supported that returns it toward its position before adjustment.

Abstract: A system for supporting and adjusting the position of an object in a vacuum includes inner and outer support rings that are connected by flexible mounts that are compliant along one axis and stiff along other axes, and drivers extending through the wall of the vacuum chamber that move the supports independently along their respective axes. At least the inner support is clamped after adjustment by a clamp that exerts a strong clamping pressure while exerting transverse force only less than a threshold selected to avoid motion after adjustment.

Abstract: An electron beam lithography apparatus has a first chamber for holding a workpiece with the first chamber having an outer wall with an opening therein. A second chamber has an electron beam column mounted therein, with the second chamber positioned adjacent the first chamber and having an outer wall having a portion in common with the portion of the outer wall of the first chamber containing the opening. An electron beam column in the second chamber includes an aperture and generates an electron beam through the aperture and the opening at the workpiece. The apparatus includes a first pump for creating a vacuum in the first chamber, a second pump for creating a vacuum in the second chamber, a first vent for permitting gas to enter the first chamber for increasing the pressure in the first chamber, and a second vent for permitting gas to enter the second chamber for increasing the pressure in the second chamber.

Abstract: An electron beam system employs a non-saturating detector for measuring total beam current that comprises a thin membrane of only a few microns thickness placed before a detector and separated from the detector by a drift space of about 10 mm, so that electrons in the beam are not absorbed to any significant extent, but are scattered transversely to spread the beam and avoid local saturation of the detector.

Abstract: The presence of magnetic fields from lenses and other (e.g. parasitic) sources at locations in a charged particle beam system such as the charged particle emitter, where the particles have little or no kinetic energy, creates disturbances of the charged particle trajectories, generating undesired angular momentum and resulting in excessive aberrations and associated adverse effects on system performance. Solutions are provided by suppression of these magnetic fields, by relocating the charged particle emitter away from the field source and/or counterbalancing the field with a bucking field. In addition, residual irrepressible field asymmetries are compensated by a suitable element such as a stigmator located at the correct location in the beam path, permitted by relocation of the charged particle emitter.

Abstract: The present invention relates to a method and apparatus of fabricating electromagnetic coil vanes. The method involves placing a bonding composition on opposing surfaces of a substrate. First and second complementary coil patterns are formed, and are aligned and bonded to respective clamp plate fixtures. The first complementary coil pattern is bonded to one surface of the opposing surfaces of the substrate via the bonding composition, and the second complementary coil pattern is bonded to the other surface of the opposing surfaces of the substrate via the bonding composition. The bonding composition is cured, and the clamp plates are removed from the first and second complementary coil patterns.

Abstract: An electron beam system employs a non-saturating detector for measuring total beam current that comprises a thin membrane of only a few microns thickness placed before a detector and separated from the detector by a drift space of about 10 mm, so that electrons in the beam are not absorbed to any significant extent, but are scattered transversely to spread the beam and avoid local saturation of the detector.

Abstract: The presence of magnetic fields from lenses and other (e.g. parasitic) sources at locations in a charged particle beam system such as the charged particle emitter, where the particles have little or no kinetic energy, creates disturbances of the charged particle trajectories, generating undesired angular momentum and resulting in excessive aberrations and associated adverse effects on system performance. Solutions are provided by suppression of these magnetic fields, by relocating the charged particle emitter away from the field source and/or counterbalancing the field with a bucking field. In addition, residual irrepressible field asymmetries are compensated by a suitable element such as a stigmator located at the correct location in the beam path, permitted by relocation of the charged particle emitter.

Abstract: An electronic beam lithography tool providing dimensional stability. The tool includes three or more deflection plates above an aperture diaphragm which allows the beam to be deflected away from an aperture and along a two-dimensional locus on the aperture diaphragm which is approximately symmetrical around the aperture therein. By doing so, the aperture diaphragm is symmetrically heated by the power of the charged particle beam and the geometry of the charged particle beam device is stabilized against variance in geometry of the device to a very small tolerance.

Abstract: A beam-limiting aperture truncates selected portions of a charged particle beam illuminating portions such as subfields of a patterned reticle of a charged particle beam projection lithography tool and then projects a pattern of charged particles onto a target in a charged particle beam lithography tool. The respective portions of the reticle are patterned in accordance with respective portions of an integrated circuit or other desired pattern and may have differing transmissivities; altering beam current at the target even when source beam current remains substantially constant. The portion of the beam which is truncated, thus altering the particle trajectory semi-angle and numerical aperture of the tool is controlled in accordance with the transmissivity of the reticle portion to enhance resolution to near optimal limits.

Abstract: A beam-limiting aperture truncates selected portions of a charged particle beam illuminating portions such as subfields of a patterned reticle of a charged particle beam projection lithography tool and then projects a pattern of charged particles onto a target in a charged particle beam lithography tool. The respective portions of the reticle are patterned in accordance with respective portions of an integrated circuit or other desired pattern and may have differing transmissivities; altering beam current at the target even when source beam current remains substantially constant. The portion of the beam which is truncated, thus altering the particle trajectory semi-angle and numerical aperture of the tool is controlled in accordance with the transmissivity of the reticle portion to enhance resolution to near optimal limits.

Abstract: An e-beam lithographic system capable of in situ registration. The system has an optics section such as a VAIL lens. A controllable stage moves a substrate with respect to the beam axis to place substrate writing fields beneath the beam. A field locking target between the optics section and the stage has an aperture sized to permit the beam to write a target field on the substrate. The field locking target includes alignment or registration marks around the aperture. A differential interferometric system measures the relative positions of the field locking target and the stage and controls stage position. The beam patterns the substrate on a field by field basis. As the stage is moving into position for each field, the beam is swept until it hits the alignment marks, thereby checking system alignment. The beam control data, i.e., coil currents necessary to hit the marks are stored, and drift correction values calculated from the beam control data.