Abstract: Three-axis particle impact probes detect particle impact vectors along x-, y-, and z-axes by spherical probe head mounted on the outer end of a shaft that is flexibly mounted in silicone rubber at the top of a housing so as to enable motion imparted to the head upon impact to be transmitted to a grounded electrode secured to the shaft within the housing. Excitable electrodes are mounted in the housing in a fixed position, spaced apart from the ground electrode and forming, with the ground electrode, capacitor pairs. Movement of the ground electrode results in changes in capacitance, and these difference in capacitance are used for measurement or derivation of momentum vectors along each of the three axes. In one embodiment, the ground electrode is mounted at the base of the shaft and is secured to a silicone rubber layer at the top of the housing, providing for cantilevered movement.

Abstract: An electrode system (ES) according to the present invention provides greater flexibility in choosing the shape of the sample to be investigated, and reliable measurements when oriented in either a horizontal or vertical position. Moreover, means are provided for easily maintaining and calibrating the parallelism of the electrodes.

Abstract: A tomographic flow imaging system comprising three or more capacitance electrodes positioned around a pipe through which a flow to be monitored passes. The capacitance between each pair of the electrodes is measured, and an output is derived from the measured capacitances which is representative of the distribution of material within the pipe. A predetermined voltage signal is applied to one electrode at a time, and the electrodes other than said one electrode are connected to sources of equal fixed potential. The capacitance of each pair of electrodes is measured by measuring charge flowing between the said other electrode of the pair and the source of potential to which it is connected.

Abstract: This invention provides an in situ monitoring technique and apparatus for chemical/mechanical planarization end point detection in the process of fabricating semiconductor or optical devices. Fabrication of semiconductor or optical devices often requires smooth planar surfaces, either on the surface of a wafer being processed or at some intermediate stage e.g. a surface of an interleaved layer. The detection in the present invention is accomplished by means of capacitively measuring the thickness of a dielectric layer on a conductive substrate. The measurement involves the dielectric layer, a flat electrode structure and a liquid interfacing the article and the electrode structure. Polishing slurry acts as the interfacing liquid. The electrode structure includes a measuring electrode, an insulator surrounding the measuring electrode, a guard electrode and another insulator surrounding the guard electrode.

Abstract: A capacitance probe (10) includes readily removable outer layers (64,66) which facilitate its use in the field to measure the width of slots or clearances (12) of different widths; an optionally perforated guard electrode (64,66,76,82) which permits width measurements over wider side wall bands with minimal effect on sensitivity; convergent or tapered side edges (102) to ease insertion and movement of the probe and a carrier block (124) which ensures proper positioning of the probe within such slots.

Abstract: A capacitive dimensional measurement chain with linear output is essentia comprised of a capacitive sensor formed by a central detection electrode and a guard electrode surrounding the detection electrode that are respectively powered by two a.c. bias voltage sources. The chain also comprises a reference capacitor and a measuring circuit for measuring the distance between the detection electrode and a conductive part placed facing the detection electrode. The bias voltage sources are variable level sources and are level-controlled by a distance measurement signal issued by the measuring circuit. The measuring circuit comprises a level amplifier and a demodulator for amplifying and demodulating an incoming error signal representative of a difference between a load of a sensor capacitance that is defined between the detection electrode and the part separated by the distance to be measured, and a load of the reference capacitor.

Abstract: The present invention relates to apparatus for measuring the level and/or the volume of liquid contained in the tank. The apparatus being of the type comprising a capacitive probe including at least two generally vertical parallel separate main plates for immersing in the liquid, and capacitance-measuring means having a detection input and a ground, the detection input being connected to a first one of the main plates and the ground being connected to the second main plate, wherein the first plate is surrounded by a guard ring.

Abstract: A distance-measuring apparatus for measuring the distance between a capacitance-type sensing probe (60) and a nearby surface of a conductive body is provided. A probe (60) includes a plurality of measuring electrodes (56.sub.l -56.sub.n) and a grounding electrode (58). The grounding electrode protrudes from the probe and grounds the nearby surface of the conductive body. A control system (10) is connected to the probe (60). A processor (12) issues control instructions, S.sub.CTL, to a selector (16). The selector (16) selects one of a plurality of measuring electrodes (56.sub.l -56.sub.n) and connects the selected electrode to a converter (14). A charging circuit (18) applies a charging voltage to the selected electrode, causing a capacitor formed by the selected electrode and the nearby surface of the conductive body to charge up. A timing circuit (22) starts a counter (32) when one of the measuring electrodes (56.sub.l -56.sub.n) is selected and stops the counter (32) when a capacitor charge voltage, V".sub.

Abstract: An electrostatic angle resolver has a stator for producing a patterned electrostatic field, a rotor having sensivitity to the electrostatic field, a capacitive coupling providing a signal interconnection between the rotor and the stator, and an active shield supplied with a voltage signal substantially identical to that signal present on the stator thereby diminishing degradation in the strength of the signal coupled between the rotor and the stator.

Abstract: A probe (20) that inspects a countersunk hole (21) in a conductive body, such as an aircraft part (22), is provided. A plurality of nested cylinders form an electrode cartridge (54) with a countersink portion (74) having a frustoconical shape and a hole portion (76) having a cylindrical shape. A plurality of lower hole electrode strips (72) are mounted on a lower hole cylinder (110) and a plurality of upper hole electrode strips (70) are mounted on an upper hole cylinder (116). A plurality of lower countersink electrode strips (68) are coupled to a lower countersink cylinder (124) and a plurality of upper countersink electrode strips (66) are coupled to an upper countersink cylinder (132). A dielectric layer (64) covers a plurality of measuring electrode tips (67, 69, 71 and 73) and an outer surface (150) of the hole and countersink portions (76 and 74). A grounding electrode (158) is mounted on the upper hole cylinder ( 116).

Abstract: Wood grain angle information is detected electronically by use of a sensor having a common electrode and a plurality of electrodes spaced from the common electrode and arranged angularly about a sensor axis. The common electrode can serve as a sense electrode or as a drive electrode for the remaining angularly spaced electrodes. By modulating applied drive signals and demodulating the sensed signals that result from capacitive coupling of an adjacent wood specimen, values that are a function of wood grain angle are identified.

Abstract: This invention relates to the measurement of the moisture content retained in the skin, and enables accurate diagnosis of the skin conditions by a device which can be switched in the connection of measurement electrodes to measure the moisture content either in the surface or in the depth of the keratinous layer of the skin.

Abstract: A capacitance based, high resolution, incrementally encoding, position measuring system employs an array of identical replicated electrodes that are driven in unison from an RF source and mounted in proximity to a patterned monolithic reference ground plane of arbitrary size. Motion of such position-sensing arrays is monitored by measuring both the sums and the differences of the electrode displacement currents in such a way as to provide incrementally encoding position signals in both one and two dimensions together with a continuous measurement of the height of the sensor array above the patterned ground plane. In various modifications, the system and methods are applied both to one dimensional linear, as well as to two dimensional planar and two dimensional cylindrical motion measurement and control. Various techniques for eliminating the effects of spurious capacitances are also disclosed.