Abstract: An apparatus for measuring the thickness of a coating on a substrate has a bridge circuit including four coils. One coil is placed near the coated substrate and another placed near an uncoated substrate of the same material. An oscillator is connected to the bridge circuit and frequency sweeps, e.g. from 10 KHz to 10 MHz. Phase differences between the voltages induced in the coils are detected to determine conductivity changes with frequency. A method for measuring coating thickness comprises generating variable frequency eddy current in coated and uncoated substrates of the same material and comparing the generated eddy current.

Abstract: An X-ray inspection system includes an X-ray source for generating a directed X-ray beam and a linear array detector for measuring the intensity of the received radiation and generating electrical signals representative thereof. A method for aligning the detector with the directed X-ray beam includes removing any part between the X-ray source and the detector, opening an X-ray beam limiter, positioning the linear array detector for maximum signal from each detector element, reducing the X-ray beam limiter opening, detecting whether any signal from a detector element is reduced, moving the limiter for producing a maximum signal on each signal, securing the X-ray beam limiter, and positioning the detector array for maximum signal.

Abstract: An X-ray inspection system for manually or automatically performing digital fluoroscopy inspections and/or computed tomography inspections by X-ray examination of manufactured parts incorporates a computer system which automatically analyzes the inspected parts for flaws. The system includes apparatus for automatically positioning the parts in an X-ray machine for obtaining fluoroscopy and tomography views of the part and for acquiring data from the inspections at production rates. The system automatically identifies the location of rejectable flaws in the parts during the fluoroscopy scanning and subsequently identifies those locations for obtaining tomography scans, if the identified flaw location is questionable. The system can automatically reject parts containing flaws identified during the fluoroscopy inspections. This system operates in a real-time environment by providing analysis of one part while a subsequent part is being subjected to X-ray examination.

Abstract: A dark field ultrasonic transducer is constructed with an outer annular spherical or conical transducer element and an inner spherical element. The outer annular element is excited and insonifies a small portion of a part surface near a discontinuity or crack with longitudinal waves or with surface waves. The inner dark field element is not focused to be sensitive to either reflected sound or waves reradiated from the surface waves, but detects sound scattered from surface discontinuities such as a crack edge. When surface waves strike a crack edge and restrike it after reflection from the bottom of the crack, two pulses are received and the time delay between them is a measure of crack depth. The crack shape and crack depth profile are determined as the part is scanned. A sphere-cone transducer, the preferred embodiment, is fabricated by stretching thin piezoelectric polymer film over a tool having a ball embedded in a conical surface.

Abstract: A dark field ultrasonic transducer is constructed with an outer annular spherical or conical transducer element and an inner spherical element. The outer annular element is excited and insonifies a small portion of a part surface near a discontinuity or crack with longitudinal waves or with surface waves. The inner dark field element is not focused to be sensitive to either reflected sound or waves reradiated from the surface waves, but detects sound scattered from surface discontinuities such as a crack edge. When surface waves strike a crack edge and restrike it after reflection from the bottom of the crack, two pulses are received and the time delay between them is a measure of crack depth. The crack shape and crack depth profile are determined as the part is scanned.

Abstract: An ionization chamber X-ray detector which minimizes the effects of leakage X-rays in systems where a collimator is employed to define resolution. The active collection volume of each detector element is reduced to the actual volume occupied by the negative ion cloud resulting from an incident X-ray beam for optimum response to desired radiation while minimizing response to leakage radiation by a combination of reducing the width of the collector electrodes with wider spaces in between the collector electrodes, and providing metallized guard electrodes between the collector electrodes. The guard electrodes serve to collect electrons freed by ionization between the collector electrodes resulting from "noise" X-rays, preventing these particular electrons from building up a space charge, or from reaching the actual collector electrodes. In addition, electric field distortions are minimized, with a consequent avoidance of adverse effects on detector response characteristics.

Abstract: Anode life in an x-ray tube is extended by applying a reduced power density to the anode to afford controlled heating of the anode to a predetermined ductile temperature prior to operating the tube at full power. Controlled heating of the anode is accomplished by defocusing the electron beam for a period of time sufficient to enable the anode to reach the desired temperature. The electron beam source of the tube may also be controlled during heating of the anode so as to supply a reduced beam current.

Abstract: A high intensity microfocus x-ray source for the inspection of superalloy objects and the like operates at a voltage of the order of 400-500 kV with an electron beam focal spot size of the order of 2-10 mils and at power levels of tens to hundreds of kilowatts and affords a brightness improvement of at least three thousand over conventional x-ray sources.

Abstract: A variety of technologies have been applied in the development of a bonded rid cathode. Erosion lithography is used for making the fine-detail grid structure, combining air erosion and lithographic techniques. To obtain openings of the order of 0.001 inch (one mil) or smaller, a nozzle with a high aspect ratio exit opening is used, and the cathode grid structure is scanned. A photo resist in which the grid pattern is developed is used over the molybdenum or tungsten grid film. The metal film is removed from the grid openings by chemical etching. The photo resist over the metal grid is used as a composite mask for removing the BN insulation in the openings by erosion with Al.sub.2 O.sub.3 powder from the special nozzle on the air blast gun.

Abstract: A variety of technologies have been applied in the development of a bonded rid cathode. Erosion lithography is used for making the fine-detail grid structure, combining air erosion and lithographic techniques. To obtain openings of the order of 0.001 inch (one mil) or smaller, a nozzle with a high aspect ratio exit opening is used, and the cathode grid structure is scanned. A photo resist in which the grid pattern is developed is used over the molybdenum or tungsten grid film. The metal film is removed from the grid openings by chemical etching. The photo resist over the metal grid is used as a composite mask for removing the BN insulation in the openings by erosion with Al.sub.2 O.sub.3 powder from the special nozzle on the air blast gun.

Abstract: The variety of technologies that have been applied in the development of a onded grid cathode are described. These include chemical vapor deposition of tungsten, molybdenum, iridium, BM, and Si.sub.3 N.sub.4 on both sides of a sintered tungsten cathode disk. Zirconium and titanium getters have been used to eliminate nitrogen evolution problems. Films of Si.sub.3 N.sub.4 have been added to the insulation to prevent calcium and barium diffusion into the layer and maintain adequate resistivity and breakdown strength. Plasma etching was introduced as a method of removing Si.sub.3 N.sub.4 from the cathode pores.

Abstract: A variety of technologies have been applied in the development of a bonded rid cathode. Erosion lithography is used for making the fine-detail grid structure, combining air erosion and lithographic techniques. To obtain openings of the order of 0.001 inch (one mil) or smaller, a nozzle with a high aspect ratio exit opening is used, and the cathode grid structure is scanned. A photo resist in which the grid pattern is developed is used over the molybdenum or tungsten grid film. The metal film is removed from the grid openings by chemical etching. The photo resist over the metal grid is used as a composite mask for removing the BN insulation in the openings by erosion with Al.sub.2 O.sub.3 powder from the special nozzle on the air blast gun.

Abstract: The variety of technologies that have been applied in the development of a onded grid cathode are described. These include chemical vapor deposition of tungsten, molybdenum, iridium BN, and Si.sub.3 N.sub.4 on both sides of a sintered tungsten cathode disk. Zirconium and titanium getters have been used to eliminate nitrogen evolution problems. The getter plates are also used as heat shields for the bonded heater. Films of Si.sub.3 N.sub.4 have been added to the insulation to prevent calcium and barium diffusion into the layer and maintain adequate resistivity and breakdown strength. Plasma etching was introduced as a method of removing Si.sub.3 N.sub.4 from the cathode pores.A new method, erosion lithography, is used for making the fine-detail grid structure, combining air erosion and lithographic techniques.