Abstract: An x-ray imaging apparatus receives an image-carrying x-ray beam on a flat amorphous silicon imaging panel with a light detector unit disposed behind. The imaging panel is of a multi-layered structure having sequentially a light-blocking layer which is opaque to visible light but transmissive to x-rays, a converting layer of a phosphorescent material for converting x-rays incident thereon into visible light, and a two-dimensional array of photosensitive elements of an amorphous semiconductor material such as amorphous silicon, adapted to undergo a detectable change in electrical characteristic in response to impingement of light. The light detector unit may be a simple light detector for receiving the light emitted from the converting layer and passed through regions between neighboring pairs of the array of photosensitive elements.

Abstract: Air cooled x-ray generating apparatus is provided with a unitary vacuum enclosure having a rotating anode target and a cathode assembly for generating x-rays. The cathode assembly may be placed within the vacuum enclosure through an opening in the top wall thereof, and comprises a disk which completely covers this opening. The unitary vacuum enclosure and the disk form a radiation shield. A plurality of fins are disposed on the exterior side wall of the vacuum enclosure, and a shroud is attached to the fins to provide additional protection of ambient against radiation. The cathode assembly may be placed through a side wall of the vacuum enclosure. The additional protection against excessive radiation in this design is provided by a shielding member placed in proximity to the anode target. The shielding member extends from the side wall of the enclosure and is substantially parallel to the top wall.

Abstract: An x-ray target assembly is formed by passing a rotary shaft through the center hole of a graphite disk such that the back surface of the disk rests on a flange part of the rotary shaft and the front surface is contacted by a nut which engages with the tip of the rotary shaft. Annular brazing materials are placed adjacent contact areas where the disk contacts the rotary shaft and the nut such that braze joints are made to secure the disk with the nut and the rotary shaft. Grooves may be formed on the surfaces of the nut and the flange part of the rotary shaft which contact the disk such that the brazing material can more efficiently fill the gaps between contacting surfaces.

Abstract: A charge sensitive amplifier with high common mode signal rejection includes an NPN bipolar junction transistor (BJT) and a P-channel metal oxide semiconductor field effect transistor (MOSFET) connected in a totem pole circuit configuration. The BJT base terminal receives a dc reference voltage, the MOSFET gate terminal receives the incoming data signal, the MOSFET drain terminal is grounded and the BJT collector terminal provides the output voltage signal and is biased by the power supply through a resistive circuit element. The MOSFET operates as a source follower amplifier with the transconductance of the BJT serving as the load at the source terminal, while the BJT operates as a common emitter amplifier with the transconductance of the MOSFET providing emitter degeneration. The signal gains of such source follower and common emitter amplifiers are substantially equal and of opposite polarities. Therefore, any common mode signal components due to common mode input signals present at the input terminals (i.

Abstract: An x-ray target has a substrate of a carbonaceous material such as graphite which is secured to a rotary shaft so as to rotate therewith. A portion of outer peripheral surface of the substrate is covered by a target plate, while the other portion is covered with a thin iridium layer with thickness in a range between 50 .ANG. and 250 .ANG. so that the trapped gas species like H.sub.2, CO, CO.sub.2 can escape therethrough, and to retard the diffusion of ambient gas species into the substrate while the infrared emissivity of the underlying substrate is not lowered appreciably thereby.

Abstract: An X-ray tube device and a method for construction thereof which provides the cathode assembly and the anode assembly in a nose of the X-ray tube, wherein an emitter face of each assembly is directed toward an X-ray emission end thereof. The electrons emitted from the cathode assembly travel along a path outward until striking the anode assembly which then generates the X-rays which are directed toward a beryllium window in the X-ray tube. This advantageous structure enables the anode-to-window distance to be small, resulting in a large X-ray flux towards a sample. Furthermore, the small nose of the X-ray tube enables a fluorescence detector to be positioned in an optimal location because the X-ray tube's shape does not displace the fluorescence detector.

Abstract: The present invention is directed to a cooling system and apparatus for use in radiographic devices having high output x-ray tubes. In operation, the x-ray tube generates large amounts of heat that must be removed so as to prevent damage to the tube. In the present invention, the x-ray tube is disposed within an x-ray tube housing that is connected within a closed fluid circuit through which circulates a coolant fluid. The fluid circulates through the x-ray tube housing and absorbs heat dissipated by the x-ray tube. Also connected within the closed fluid circuit is a heat exchange which cools the coolant fluid before it is recirculated back to the x-ray tube housing. Also connected within the closed fluid circuit is a centrifugal pump which continuously circulates the coolant fluid between the x-ray tube housing and the heat exchange device. The pump includes as an integral part a deformable bellows that accomodates any volume changes with the closed fluid system due to increases in temperature.

Abstract: A graphite-backed metallic x-ray tube target assembly has a rotary shaft which passes through the central opening of the annular graphite substrate and is secured to the metallic disk-shaped target. In order to protect the shaft from heat radiated from the graphite substrate, at least one tubular heat shield is brazed to the target and disposed between and separate from the inner wall of the annular graphite substrate and the outer peripheral surface of the shaft. For further protection, a tubular heat shielding member may be disposed inside the other heat shield, between the outer heat shield and the shaft. In order to minimize the heat conduction from the outer heat shield to the inner heat shielding member, they are mostly separated and attached to each other only along their bottom edges where they are tack-welded together at mutually separated positions such that the inner heat shielding member is supported entirely by the outer heat shield.

Abstract: A flat workpiece is placed in contact with a flat platen in a vacuum chamber, and is held by a uniformly-distributed force while a small mass flow of gas is introduced along a contour to form a uniform pressure region between the flat workpiece and the platen. Separation of the two surfaces due to aplanarity or surface roughness is less than the gas mean free path, and high rates of heat transfer are obtained uniformly over the area of the workpiece. A scavenging port, located outwardly of the gas introduction contour is differentially pumped to reduce the rate of gas leakage into the chamber. Preferably, pressure is provided by an electrostatic clamp (for non-insulating substrates) or other clamping arrangement which does not occlude the front surface of the workpiece. In the electrostatic clamp, the voltage activation sequence prevents workpiece vibration, while a clamping current sensor immediately detects degree of contact, e.g., due to debris on the platen, and initiates a suitable warning or control.