Abstract: Various embodiments provide a thickness sensor and method for measuring a thickness of discrete conductive features, such as conductive lines and plugs. In one embodiment, the thickness sensor generates an Eddy current in a plurality of discrete conductive features, and measures the generated Eddy current generated in the discrete conductive features. The thickness sensor has a small sensor spot size, and amplifies peaks and valleys of the measured Eddy current. The thickness sensor determines a thickness of the discrete conductive features based on a difference between a minimum amplitude value and a maximum amplitude value of the measured Eddy current.

Abstract: A measuring device for measuring a film thickness of a silicon wafer (1) comprises: position and velocity sensors (4) linearly arranged along a longitudinal direction into first and second position and velocity sensor arrays spaced apart from each other in a lateral direction, in which the position and velocity sensors (4) in the first position and velocity sensor array are in one-to-one correspondence with the position and velocity sensors (4) in the second position and velocity sensor array in the lateral direction; an eddy current sensor (2) disposed in a symmetrical plane between the first position and velocity sensor array and the second position and velocity sensor array and perpendicular to the lateral direction; and a controller connected to the position and velocity sensors (4) and the eddy current sensor (2) respectively for controlling measurement of the thickness of the film according to detection signals from the position and velocity sensors (4) and the eddy current sensor (2).

Abstract: Present embodiments include eddy current array probes having differential coils capable of detecting both long and short flaws in a test specimen and, additionally or alternatively, multiplexed drive coils. For example, an eddy current array probe may include a first plurality of eddy current channels disposed in a first row and a second plurality of eddy current channels disposed in a second row. The first plurality and second plurality of eddy current channels overlap in a first direction but do not overlap in a second direction. The probe also includes a semi-circular drive coil disposed proximate to the first plurality and second plurality of eddy current channels and configured to generate a probing magnetic field for each sense coil of the eddy current channels.

Abstract: A method and an apparatus for measuring the thickness of a metal layer. The metal layer has a resistivity (?1) that differs from the resistivity (?2) of the metal object. The apparatus includes a first device arranged to generate a magnetic field in close vicinity of the metal layer, and to generate a variation of the magnetic field so that a current is induced in the surface of the metal layer, a second device arranged to measure the changes of the magnetic field outside the metal layer due to the induced current during a time period that is longer than the time it takes for the current to propagate through the metal layer, and a computing unit to determine the thickness of the layer based on a mathematical relation between the thickness of the layer and the measured values of the changes of the magnetic field.

Abstract: A method and an apparatus for enhancement of the for measuring resistance-based features of a substrate is provided. The apparatus includes a sensor configured to detect a signal produced by a eddy current generated electromagnetic field. The magnetic field enhancing source is positioned to the alternative side of the object under measurement relative to the sensor to enable the sensitivity enhancing action. The sensitivity enhancing source increases the intensity of the eddy current generated in the object under measurement, and as a result the sensitivity of the sensor. A system enabled to determine a thickness of a layer and a method for determining a resistance-based feature characteristic are also provided.

Abstract: The calibration of a laser caliber is described. The laser caliber uses first and second sensors to determine the distance to different sides of a sheet. A third sensor is used to determine the distance between the first and second sensors. The calibration of the first, second, and third sensors is done by positioning a test object onto the platform sensed by the third sensor. The platform is moved to multiple positions in order to calibrate the first, second and third sensors. Since the displacement of the platform moves the distance to the target of the first, second and third sensors the same amount, the sensors can be accurately calibrated for a number of different positions of the test object. A very accurate calibrating displacement measuring device such as an LVDT can be used.

Abstract: A measuring gage for determining the thickness of a non-metallic material utilizes an inductive sensor positioned on one side of the material to be measured and a metallic object placed on the opposite side. The output of the sensor is used to determine the distance between the sensor and the metallic object, and hence the thickness of the material. The movement of the sensor and the metallic object can be computer controlled to map the thickness of the material along a predetermined path and produce a cross-sectional thickness profile. The output of the sensor can be used in conjunction with a computer controller responsible for adjusting the size of a score line to prepare an airbag deployment section in a vehicle trim panel.

Abstract: A sensor for monitoring a conductive film in a substrate during chemical mechanical polishing generates an alternating magnetic field that impinges a substrate and induces eddy currents. The sensor can have a core, a first coil wound around a first portion of the core and a second coil wound around a second portion of the core. The sensor can be positioned on a side of the polishing surface opposite the substrate. The sensor can detect a phase difference between a drive signal and a measured signal.

Abstract: An apparatus for and a method of measuring material thickness with magnetics. The thickness monitoring system includes a thickness monitor, a probe, and a target. In a preferred embodiment, the probe is positioned on one side of an article for which the thickness is to be determined. The target is positioned on the opposite side of the article from the probe. The probe includes an excitation coil, a field compensation coil, and a magnetic sensor. The method includes energizing the excitation coil to excite a response from the target, compensating for the effect of the excitation coil on the magnetic sensor, measuring the response of the target with the magnetic sensor, and determining the thickness of the article from the measured response. The preferred mode of energizing the excitation coil is with an AC waveform; however DC, multi-frequency AC, or a combination of AC and DC waveforms may be used.

Abstract: A measuring probe in a paper measuring apparatus is kept at a distance from the surface of the paper by feeding medium between the paper and a surface of the measuring probe through a feed hole in the surface of the measuring probe. The pressure of the supplied medium, the dimensions of the feed hole and measuring probe, and the distance of the probe surface from the paper are arranged such that after the medium is discharged from the feed hole, the rate of the flowing medium increases so as to produce an underpressure, which generates a force tending to move the paper and the measuring probe toward each other. The discharge of the medium from the feed hole produces an opposite force urging the paper and probe away from each other, and the measuring probe and paper settle in a state of equilibrium determined by the two forces.

Abstract: A device that can sense small changes in distance between opposed surfaces includes a ferromagnetic material and a giant magneto resistance effect sensor. A current source applies a current to the sensor to operate the sensor and read the magnetic field that impinges on the sensor from the ferromagnetic material. The magnetic field changes when the distance between the opposed surfaces changes. The device can be used in imaging apparatus to sense multifeeds and other conditions.

Abstract: A pair of elastic strips are provided in order to hold sheet material to be measured in thickness. Each of the elastic strips includes of one or more elastic films. Ends of the elastic strips are supported by support portions, and the other ends of the elastic strips are provided with respective coils, opposed to push each other, and kept in contact with each other. When the sheet material is held between support portions, the inductances of the coils are changed and the thickness of the sheet material is detected as an electric signal representative of the changed inductance.

Abstract: A caliper gauge for moving sheet material such as paper which measures the thickness of the paper accommodates bumps or holes in the paper by providing at least one side of the caliper gauge with a long continuous smooth arm which because of its mounting in close proximity to the moving sheet, which is partially made possible by the use of air bearings for the upper and lower portions of the gauge, provides a gradual wedge-shaped opening which thus allows the transfer of the momentum of the bump or hole in the paper to gradually overcome the inertia of the measuring arm which is pushed away from the paper. The arm itself is made of a single piece of sapphire and is universally pivoted by the use of a polyimide material adhered to the top of the arm which gives the arm at least 2.degree. of dimensional freedom while still maintaining it aligned in the moving direction of the paper.

Abstract: A preform test fixture for receiving a blow molding preform includes a structural base, a measuring device mount, a support arm, and a bar member having preform bores. The bar member is adjustable so that it translates up and down on the support arm, and is removably fastened thereto by a knob assembly screwed into a hole in the bar member. The system includes utilizing several bar members to enable the fixture to measure wall thicknesses of a virtually unlimited number of unique preform designs. The fixture also has a pivot device that enables the bar member to pivot on the support arm. The measuring device mount is adjustable on the base. The adjustment capability of the fixture enables uniform and repeatable wall thickness measurements, concentricity measurements at various locations, and preform tip wall thickness measurement proximate the preform gate.

Abstract: An openable ring assembly is externally centered around and moved parallel to the centerline of a stationary pipe. As a low-frequency EM source signal is applied to the ring assembly, the time and/or frequency shifts of a detected EM signal from the source signal can be correlated to pipe wall thickness without removal of external pipe insulation and metal cladding, if present. The ring assembly may be opened or expandably segmented to allow pipe thickness detection around obstructions or larger diameter pipe. Centering is preferably accomplished by using rollers circumferentially attached to the ring assembly.

Abstract: A measuring device scanning from edge to edge of a continuously fed sheet includes two sensing heads spaced apart from the sheet by air cushions whose thickness is not influenced by pressure of supplied air and is subjected to an invariable approaching gravimetric force. The air cushions are preferably formed of air jets from calibrated holes at the inside of both sensing heads, each of said holes being surrounded by annular barriers with circular rims. While the approaching force applied to the upper head is given by the own weight of the latter, the corresponding opposed force on the lower head is provided by a pressure regulator of internal air at the inside of the lower sensing head.

Abstract: A caliper sensor of the opposing contact type, wherein are provided target supporting spherical surfaces comprising at least three spherical surfaces disposed on a periphery of a target facing plane of a sliding surface and a plane determined by the tops of each spherical surface and in contact in parallel with a measurement reference plane above the target; and contact spherical surfaces for the reference plane outside the target facting plane of the sliding surface, whose number is equal to or greater than that of the relevant target supporting spherical surfaces and the tops of each spherical surface having a height about equal to the relevant target supporting spherical surfaces, so that contaminants are steered away from the tops of the spherical surfaces and the measurement process is thereby unaffected by the contaminants for a long period of time.

Abstract: In the rolling probe, the measuring pole is designed as a rotating, rotationally symmetrical roller (4), such as a disk, cylinder or sphere, which directly contacts the surface of object to be measured (5) and is placed in the range of a sensor system. As a result, the maximum possible signal deviation can be fully used for the measuring. An increased measured value resolution and measuring accuracy especially in the measuring of thin sheets is achieved. Further, the actual thickness measuring takes place at the contact point with the layer to be measured. Thus, a true "one-point measuring" is involved.

Abstract: Apparatus for measuring the thickness of a moving web of material in which a ferromagnetic core carrying a winding and a ferromagnetic disc are disposed on opposite sides of the web at constant distances therefrom with at least one of said distances being maintained by a servomechanism including an optical distance measuring device whereby the inductance of said coil is a measure of the thickness of the web.

Abstract: A sheet material in the form of a transparent film, paper sheets, or the like, is made machine visible or recognizable by recognition enhancing elements. These elements are of such a nature that they are machine readable, e.g. by optical, electrical, or magnetic sensors to increase the machine visibility of any slivers that may have remained in and/or on a prepreg or stack of prepregs. The signals sensed by photosensitive and/or magnetic and/or electric sensors are so processed that an alarm is provided when a sliver or remnant of the sheet material has been detected, and so that the location of such a sliver may be indicated.

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: Method for measuring the thickness of a lubricant film between two surfaces which are in motion with regard to one another, characterized by the fact that a lubricant with high relative permeability is used, whereby the polar pieces of an electromagnetic sensor are brought into contact with the lubricant film to be measured in such manner that they are bridged by the lubricant film.

Abstract: A caliper gauge for relatively thin moving sheet material is provided by the use of a pair of outer ring air bearings flexibly supported which tend to flatten the sheet. An inner central portion of each ring respectively carries active and passive magnetic circuit means with the passive means being supported by an elongated strap of Kevlar which is elongated in the machine direction of the sheet material. This provides for very low unsprung weight.

Abstract: A distributed transmission line network for connecting a plurality of DUTs to a low-power driver includes a plurality of distributed transmission lines with distributed capacitors. The distributed capacitors are added to the distributed transmission lines to make the propagation delay on each line equal, thereby eliminating skewed input signals to the DUTs. The capacitors also minimize capacitive cross-talk between the plurality of distributed transmission lines. The distributed transmission line network includes a driver with an internal resistance that is much less than the characteristic impedance of the distributed transmission line to minimize the voltage drop at the driver. The distributed transmission line also includes an input RC network for speeding rise time and a termination RC network for minimizing reflections in the distributed transmission line.

Abstract: A contacting caliper gauge measures the thickness of a moving sheet material. The gauge has two sheet contacting pads, one on either side of the sheet. At least one sheet contacting pad of the caliper gauge is aerodynamically designed to limit and/or reduce the tendency of boundary layer air travelling with the sheet to raise the sheet contacting pad off of the sheet surface. The caliper gauge also includes an electromagnetic proximity sensing device for determining the distance between the caliper pads, and thereby the sheet thickness. The gauge includes a caliper pad having an electromagnetic core having two pole faces mounted to that portion of the caliper pad remaining in closest proximity to the moving sheet surface. In on embodiment, the caliper pad has a vacuum notch which pulls the rear half of the pad, and in particular the rear end of the pad, in close proximity to the moving sheet.

Abstract: A device for measuring the thickness of a wet or dry paint film applied on a substrate without contacting the film is disclosed. The device uses an ultrasonic sensor positioned adjacent to an inductive eddy-current proximity sensor where the ultrasonic sensor measures the distance between the device and the upper surface of the paint film and the proximity sensor measures the distance between the device and the upper surface of the substrate. The two distances measured, when compared, produce the film thickness value. The device is capable of accurately measuring thickness of various paint films, such as flat, glossy and metal-flake containing paint films.

Abstract: A protective backing for composite sheets and a method of detecting the presence of protective backing within a stack of composite sheets. The protection of the surfaces of uncured composite sheets is provided by applying a protecting backing having a metal component to the composite sheet, which is removed prior to layup and curing of a composite laminate. Presence of the protective backing in a layup of composite sheets or a laminate made from the layup composite sheets may be detected by passing them through a sensing presence of an eddy current.

Abstract: A caliper gauge for relatively thin moving sheet material is provided by the use of an outer ring type air bearing, flexibly supported, which is flexibly connected again to an inner air bearing carrying the magnetic measuring components. The outer air bearing (with its juxtaposed mate) tends to flatten the sheet so that minimum movement is required of the independently actuated inner air bearing. Thus, great accuracy is achieved and tearing or marking of the sheet material, such as super calendered or coated grades of paper, is avoided.

Abstract: A system is described for connecting a printed circuit board (PCB) under test to a digital analysis unit to permit verification of the functional behavior of the PCB. A bed-of-nails (BON) fixture is employed, allowing access to internal circuit nodes of the PCB. Controlled-impedance wiring, terminated in its characteristic impedance at the test electronics, allows high speed signals to be communicated without degradation from the unit under test (UUT). Excessive dynamic loading of the UUT circuit nodes is avoided by employing isolation resistance at each BON probe. The potentially large number of UUT signals to be monitored is multiplexed down to a smaller number of lines more readily accommodated by the digital analysis unit. The selected signals from the UUT are processed in a wide-band asynchronous manner by the test electronics in such a way that uniform delay of all signals through the multiplexer is achieved.

Abstract: A thickness measurement of non-metallic material molded bodies, particularly, walls of tubular ceramics or plastics, can be simply performed with a high precision, by interposing such a molded body between a metal and a measuring probe, such as a solenoid coil, generating an alternating magnetic field, and measuring an energy loss of the magnetic field which depends on the thickness of the molded body. The energy loss can be measured by detecting a variation of voltage of an A.C. bridge circuit including said coil as a component.

Abstract: An improved method and apparatus for monitoring the thickness of a film includes a sensor roll which cooperates with a compliant roll to form a nip through which the film passes. As the two rolls rotate relative to each other, magnets disposed in the sensor roll are sequentially moved to and from the nip. As a magnet moves by the nip, the field emanating from the magnet is concentrated by a body of material having a relatively high magnetic permeability and disposed in the compliant roll. This results in an induced voltage being generated in a sensor coil. The output from the sensor coil is transmitted to control circuitry which effects operation of a suitable apparatus to control the thickness of the film.

Abstract: An arrangement for measuring the thickness of a continuous material web. The thickness of the material web is measured by pressing from opposite sides of the web, and on the same spot, wheels which can rotate against the web. One wheel is equipped with a conductive surface, and the other wheel has a detecting element which measures the distance from the conductive surface.

Abstract: An improved method and apparatus for monitoring the thickness of a film includes a sensor roll which cooperates with a compliant roll to form a nip through which the film passes. As the two rolls rotate relative to each other, magnets disposed in the sensor roll are sequentially moved to and from the nip. As a magnet moves by the nip, the field emanating from the magnet is concentrated by a body of material having a relatively high magnetic permeability and disposed in the compliant roll. This results in an induced voltage being generated in a sensor coil. The output from the sensor coil is transmitted to control circuitry which effects operation of a suitable apparatus to control the thickness of the film.

Abstract: An apparatus for testing the wall thickness of a moving tube of plastics or other electrically non-conducting material being produced by an extruder, comprises an electrically conductive measurement body arranged in the moving tube, a ferromagnetic holding member which is arranged in the tube within effective range of a holding magnet located outside the tube and which has a tie connection to the measurement body to locate the measurement body axially within the effective range of a measuring sensor located outside the tube. The holding member and the measurement body may be introduced into the tube through a channel in the extruder head, shot into the tube from a forward position, or inserted through an aperture cut in the tube wall.

Abstract: A device for the measurement of the wall thickness of tubes, in particular for the measurement of extruded synthetic tubes during the extrusion process, comprises a common support for location within the tube and a plurality of measuring bodies mounted on the support and urged resiliently outwards for engagement with the tube wall. In order to provide a sufficiently robust support for the measuring bodies they are connected to the support by means of a parallelogram linkage, and in order to allow the measuring bodies a degree of free movement so that they can conform to the contour of the tube wall at least one parallelogram arm of the parallelogram linkage is pivoted with free play.

Abstract: Apparatus for measuring the wall thickness of a moving tube, for example an extruded tube of synthetic plastics material, comprises means for location in a stationary position within the tube and adapted to present at least one measuring body in resilient contact with the inner wall of the tube, and an external sensor for sensing the position of the measuring body. A mechanical linkage incorporating means engaging the tube wall is arranged to lift the measuring body away from the tube wall when excessive friction between the tube wall and the engagement means indicates a condition liable to damage the measuring body.

Abstract: A contacting caliper gauge measures the thickness of a sheet material moving from the anterior to the posterior of the gauge. The gauge has two matched heads, one to either side of the sheet. Each head has a base, a skid and a bellow. The skid is hinged to the anterior of the base and is between the base and the sheet. The other end of the skid is attached to a bellow. The bellow is also attached to the posterior of the base and is substantially perpendicular to the sheet. A cap is attached to the bellow. The cap has a surface parallel to the sheet near the posterior and beveled near the anterior. The two heads are positioned with the bellow of one in line with the bellow of the other.

Abstract: A pair of elastic strips are provided in order to hold sheet material to be measured in thickness. Each of the elastic strips includes of one or more elastic films. Ends of the elastic strips are supported by support portions, and the other ends of the elastic strips are provided with respective coils, opposed to push each other, and kept in contact with each other. When the sheet material is held between support portions, the inductances of the coils are changed and the thickness of the sheet material is detected as an electric signal representative of the changed inductance.