Abstract: An optical delay line includes first and second hollow front surface retroreflectors. A translator is coupled to one of the first and second retroreflectors for adjusting the distance between the retroreflectors while maintaining the optical relationship between them. An entrance is provided for introducing a light beam into the delay line so that the light beam is reflected between the first and second retroreflectors a plurality of times; and an exit is provided to couple the beam out of the delay line.

Abstract: Both a system and a method are provided which allows an eddy current probe to accurately determine both the proximity and dimensions of non-conductive structures which are normally invisible to such probes. The system includes a portable target medium that is movable into a known position with respect to the non-conductive structure, and that includes a conductive material that couples strongly with a fluctuating magnetic field, and a movable eddy current probe that emanates a fluctuating magnetic field and which generates a signal indicative of the magnitude of the interaction between the field and the portable target medium from which the distance between the two may be computed. The system may be used to determine the proximity of non-conductive structures such as plastic pipes that have been buried under ground, as well as the dimensions of such non conductive structures.

Abstract: A device and method for guided testing of an object, and in particular, an internal structural component in an object, using non-destructive ultrasonic techniques is provided. A housing containing at least one ultrasonic transducer probe is adapted to be placed directly on the surface of the object to be tested. Eddy current probes are provided in the housing to guide the ultrasonic probe such that the ultrasonic energy will be directed at the appropriate internal structural design component of the object to be inspected. A microcomputer is then used to record the data obtained using ultrasonic signals and the position on the object using the information designed from the eddy current probes.

Abstract: A method and apparatus for securing or attaching a rotor blade with a turbine rotor cavity by disposing an expanding material between the blade root and the cavity walls. The expanding material comprises a naturally occurring mineral which expands to a great degree when exposed to elevated temperatures. The expanding material may be provided in the form of shims made directly from the expanding material or made from a composition of the expanding material and a binder such as a polymer or elastomer. Alternatively, the expanding material may be provided in the form of a liquid vehicle applied to surfaces of the cavity walls. The expanding material is located at specific positions within the cavity to urge certain surfaces of the blade root against certain surfaces of the cavity walls. In this manner, the blade can be forced into a tight fit and an aligned position, with respect to the rotor, upon expansion of the expanding material.

Abstract: Both a system and a method for determining the length of a discontinuity such as a crack or other fault in the interior wall of a steam generator heat exchanger tube is disclosed herein. The apparatus generally comprises an elongated probe assembly which includes a plurality of eddy current coils mutually separated at known distances with respect to each other along the longitudinal axis of the probe, and an eddy current coil actuating device for separately and independently actuating each of the coils to provide an adjustable electromagnetic sensing field. In the method of the invention, the probe assembly is positioned adjacent a discontinuity and then each eddy current coil, separated by a known distance, is independently actuated and its reading recorded to determine which of the coils actually detects the discontinuity.

Abstract: A diagnostic filter device for monitoring electrically conductive and semiconductive particles entrained by a fluid, composed of:a filter element (4) disposed to receive the fluid and to permit passage of the fluid while retaining particles entrained in the fluid;a component (8) disposed for producing an alternating electromagnetic field which extends across at least one region of the filter element (4); andan eddy current detecting instrument (12) connected to the electromagnetic field producing component (8) for detecting the influence on the field of particles in the filter element region.

Abstract: Both an apparatus and a method for simultaneously inspecting the walls of a tube with both ultrasonic and eddy current probes is disclosed herein. The apparatus generally comprises a cylindrical housing assembly insertable within the tube to be inspected, and a probe carrier rotatably mounted within and helically movable with respect to the housing. The probe carrier holds three ultrasonic probes for transmitting ultrasonic beams which are directly oriented radially, chordally, and axially with resepect to the longitudinal axis of the tube, as well as an eddy current probe for simultaneously inspecting the walls of the tube with electromagnetic lines of flux. The apparatus further includes a helical drive train formed from a lead screw assembly having a motor means, a drive shaft, and a drive sleeve for imparting a helical scanning motion to the probe carrier with respect to the housing.

Abstract: A system and method for nondestructively inspecting and monitoring materials that indicates the structural integrity of the material is disclosed. The inspection method includes the following steps. First, the material to be subsequently monitored, is tagged by dispersing a small amount of finely divided particles throughout the material. The tagged material is then applied in accordance with its application, such as adhesive material to two pieces to be joined to form an adhesive joint. When the adhesive joint or other material is to be inspected, the tagged particles are activated to cause an inherent structural resonance in the tagged material. The activation and structural resonance of the material is then monitored and measured with a probe. Finally, the structure resonance of the material is related to the structural integrity of the adhesive joint, the matrix-reinforcement interface integrity of a composite material, or the state of cure of a resin.

Abstract: Both an apparatus and a method for simultaneously inspecting the walls of a tube with both ultrasonic and eddy current probes is disclosed herein. The apparatus generally comprises a cylindrical housing assembly insertable within the tube to be inspected, and a probe carrier rotatably mounted within and helically movable with respect to the housing. The probe carrier holds three ultrasonic probes for transmitting ultrasonic beams which are directly oriented radially, chordally, an axially with respect to the longitudinal axis of the tube, as well as an eddy current probe for simultaneously inspecting the walls of the tube with electromagnetic lines of flux. The apparatus further includes a helical drive train formed from a lead screw assembly having a motor means, a drive shaft, and a drive sleeve for imparting a helical scanning motion to the probe carrier with respect to the housing.

Abstract: An improved eddy current probe system and method for simultaneously detecting different types of flaws at different depths within a metallic wall, such as a section of Inconel tubing, is disclosed herein. The system comprises a current generator for generating alternating currents of substantially different frequencies, a probe head including first, second and third concentrically arranged coils in separate communication with the current generator, shielding material disposed between the coils for preventing cross talk between each coil and the pulsating magnetic field of the coils adjacent to it, and a detector circuit which may include an inductive bridge for providing an electrical output representative of the impedance changes in the respective coils. In operation, each of the coils conduct currents having substantially different frequencies, the highest frequency being conducted by the smallest-diametered coil and the lowest frequency being conducted by the largest-diametered coil.

Abstract: A process provides a method for attaching a turbine blade to a blade support such as a rotor or rotor disc of a turbine. The root portion of the blade is formed to a shape approximately that of a groove in the surface of the rotor or rotor disc and the root portion of the blade is inserted within the groove. A composition comprising a particulate compound selected from the group consisting of a ceramic, graphite metal, metal alloy and mixtures thereof is positioned between the root portion of the blade and steeples, located one on either side of the groove.

Abstract: Rapid nondestructive testing of a ferromagnetic workpiece for creep damage is carried out by placing an eddy current coil adjacent to the workpiece, passing an alternating current through the coil, measuring the eddy current response as influenced by the workpiece, and comparing the current measurement to a current calibrated to known creep damage for the given ferromagnetic material. Correlations of the eddy current response to creep rate and time to failure are generated from creep rupture tests performed on specimens of the given material subjected to varying conditions of time, temperature and stress. Qualitative tests can also be performed to identify the point of greatest creep damage by passing the eddy current coil over the workpiece to find the location of the lowest eddy current response. Conventional creep damage tests can then be performed at that location if desired.

Abstract: An optical inspection system for tubular products utilizes a feeler for engaging the internal surface of the tube to be inspected and a miniature charge coupled device video camera for viewing the interface between the feeler and the tube. An image processing computer responsive to the output of the video camera produces information for rapidly assessing damage or distortion of the tube. The camera is pulled or pushed through the tube while continuously monitoring the optical contrast between the feeler and the tube wall. The camera image of the tube ID is fed to the image processing computer to determine and record changes in ID contour is a function of the axial position of the camera and feeler. These data in turn can be used in tubing life prediction considerations. The data may be analyzed manually if desired.

Abstract: The stress or strain in a magnetic workpiece is measured by a method in which the workpiece is locally magnetized by a constant magnetic field, an eddy current probe is placed adjacent to the workpiece, and an electrical characteristic of the probe, which is proportional to stress or strain in the workpiece is measured. The measured value is compared to calibration data to obtain the actual stress or strain. By continually subjecting the workpiece to a constant magnetic field, a maximum value of applied stress can be determined by making a first measurement before an external force is applied to the workpiece and making a second measurement after the force is removed. The difference between the two measurements is proportional to the maximum stress applied to the workpiece by the force between the two measurements. If stress or strain in a nonmagnetic workpiece is to be measured, a layer of magnetic material is bonded to the workpiece at the measurement point.

Abstract: A tissue photoradiation system uses a hematoporphyrin or hematoporphyrin derivative dye in tissue to be irradiated and arranges a xenon ion laser 10 for simultaneous lasing. Deep blue light is produced at wavelengths of about 406-427 nanometers and red light at a wavelength of about 627 nanometers by using partially transmitting mirrors 12 and 13 arranged at opposite ends of the laser resonator. Mirror 12 has a coating 14 that substantially reflects blue light and partially transmits red light to produce a red light output, and the coating 15 of mirror 13 substantially reflects red light and partially transmits blue light producing a blue light output. The blue light output is transmitted to a diagnostic tissue irradiator 21 to illuminate the tissue and diagnose its condition. A transmission system using an optical fiber 25 delivers the red light to the tissue for treatment purposes. The red light is radiated out the side of an optical fiber region 30a to be directed into large area of tissue.