Itt Industries, Inc.

International Standard Electric Corporation

Renishaw Plc

International Telephone and Telegraph Corporation

Stc, Inc

Standard Telephones & Cables Limited

Renishaw Metrology Limited

Gillies D Pitt

Roger J Williamson

David N Batchelder

David Wilson

David R McMurtry

Roger E Jones

Philip Extance

Arulanandam M Prabakaran

Peter G Lloyd

Peter D Greene

Rosamund C Neat

Edward John Thrush

Harry J Smith

Christopher C Dunning

Stephen I Gregorig

David H Whysall

Philip W Black

Contact probes

A measuring system for measuring the position of an object comprises a laser (10), a laser interferometer (16), and a detector (24). A series of sensors for sensing environmental conditions are provided; the sensors may be attached to the object. The sensors transmit information back to a central control (46) via LED transmitter (54). The transmitter (54) is powered from a battery (56) which is in turn charged by transducing (with a solar cell) part of the power of the light beam (12) generated by the laser (10). The sensors may be temperature sensors, pressure sensors, humidity sensors, refractive index sensors, vibration sensors, or beam alignment sensors.

System for measuring the position in space of an object using a light

A touch-trigger probe is provided with a sensor (which may be a mirror (106), an optical fibre (206), or a bi-refringent element (307)) which changes state by vibrating or undergoing strain when a stylus connected to the probe contacts a workpiece. The sensor is typically provided on (in the case of the mirror (106)), or in (in the case of the optical fibre (206)) the stylus. The change of state of the sensor causes a change in the path length, polarization state, or intensity of light waves conveyed by the sensor. An interferometer may be provided to detect such changes. Other forms of electromagnetic waves may be used to the same effect.

Touch probe including a waveguide

Position determination apparatus

In a fiber optic interferometric magnetic sensor or magnetic gradient detector a magnetic bias field is applied to a magnetically sensitized portion of an optical fiber by means which are driven by optical power whereby a completely passive sensor head arrangement may be achieved. In a magnetic gradient detector optical power from a high power laser (34) may be supplied via an optical fiber (35) to illuminate a solar cell 27 to whose electrical output terminals solenoids (25,26) are connected. A portion of a respective optical fiber (21, 22) which is magnetically sensitized, by for example bonding to a strip of magnetostrictive material (23, 24), is disposed inside each solenoid (25, 26).

Magnetic field sensors, in particular optical fiber magnetometers

An arrangement for the remote actuation of a controlled device, e.g. a hydraulic valve, in situations with stringent safety requirements, uses optical power. The optical power, e.g. from a high-power laser, is conveyed via an optical fibre (1) to the controlled device. Here it falls on a heat-absorbent surface (2), as a result of which a volatile fluid (e.g. freon) is evaporated. This via a bellows (4) drives an output rod (5), which operates the controlled device. Alternatives include a bimetallic strip, a thermostat-type capsule, and a memory metal strip, as the heat responsive device.

Optical actuator

A Hall effect device for responding to weak magnetic fields uses a small chip of gallium arsenide located between the overlapped ends of two flux concentrators. The spacing between the concentrators may be as small as 95 micrometers. The flux concentrator, which serve to enhance the device's sensitivity are made of amorphous magnetic material, i.e. a metallic glass, which has high permeability.

Hall effect device with overlapping flux concentrators

In order to determine the vortex shedding frequency, from which the fluid flow rate may be calculated, an optical beam, such as produced by a laser, is passed through a fluid, transversely to a vortex street therein, and modulated in dependence on the alternate high and low velocity regions comprising the vortex street. The modulated signal is detected and 'cleaned' of noise by filtering with a first (high) band-pass filter of a center frequency f.sub.c, such that the first filter output comprises an amplitude modulated signal of carrier frequency f.sub.c modulated by the vortex shedding frequency, that is the frequency of oscillation of the power spectra between the respective curves for the high and low velocity regions. The first filter output is demodulated and filtered by a second (low) band-pass filter, whose output is of a frequency comprising the vortex shedding frequency.

Vortex shedding fluid flowmeter

A vortex flowmeter having a double bluff body arrangement whereby vortices are generated at a rate corresponding to the fluid flow velocity. The upstream body and the downstream body together interact with the fluid stream to generate vortices. The arrangement introduces a relatively low blocking factor in comparison to simple bluff body arrangements. Vortex sensors are located between the bodies and downstream of the second body a distance between three and five times the diameter of that body.

Fluid flowmeter

A Hall effect device comprises a thin substrate free epitaxially grown semiconductor body mounted in a magnetically permeable, e.g. ferrite, housing. The layer, which is preferably gallium arsenide or gallium indium arsenide, is grown on a substrate which, after device processing is complete, is removed by a selective etching process. In view of the relatively high sensitivity and good noise characteristics such a device with its flux concentrator is small, since the flux concentrators are themselves much smaller than with conventional Hall effect systems. Other semiconductor materials from which the novel thin Hall effect devices can be made include silicon.

Method of making a Hall effect device

A fluid flowmeter of the vortex shedding type. The vortex frequency is determined from variations in the internal reflectivity of a prism 16 mounted in the fluid and coupled to a light source 13 and to a detector/frequency meter 14 via an optical waveguide arrangement 15. Passage of a vortex adjacent the prism 16 causes a temporary change in the local fluid refractive index and hence a change in the intensity of light internally reflected by the prism.

Apparatus for measuring fluid flow

An optical fibre strain gauge arrangement is employed to take advantage of a so-called speckle effect. As used in a simple strain gauge, a coherent light source, e.g. a laser, launches light via a suitable launching device into a multimode optical fibre or fibre bundle. Due to slight differences in transmission times in the fibre or fibre bundle the light as received at a detector has a speckle pattern. If the fibre or fibre bundle is subjected to strain, the various transmission times are caused to change so that the speckle pattern shifts, the amount of the shift being a measure of the strain. This principle is usable in a vortex flowmeter where the vortices produced by a bluff body influence such a fibre arrangement. Further, when used underwater, passing ships and submarines may be detected. In a building, the arrangement may be used as an intruder detection system.

Fibre optic transducer

A light scattering oil-in-water detector and method. Scattered light is measured at a plurality of scattering angles, one angle being chosen such that the light scattered by the oil is substantially zero. This overcomes interference arising from suspended solids, e.g., rust.

Oil-in-water method and detector

A system for determining the concentration of oil in a mixture of oil and water including an aligned photocell and a displaced photocell spaced therefrom to receive direct and reflected and/or refracted light through a scatter cell from a laser. A logarithmic amplifier is connected from the aligned photocell because a logarithm of the output thereof is a linear function. The displaced photocell output is essentially linear over a typical range above 200 parts per million (ppm). The output of the logarithmic amplifier is essentially linear below about 200 ppm. The linear portion of each output is combined by a switch when the logarithmic amplifier output passes through a selected threshold level.

Oil concentration detector

Apparatus for detecting oil in water contained in a chamber, wherein a semiconductor laser directs infrared radiation into the chamber. The radiation is scattered and detected by one or more cells. The output of one cell controls the gain of an amplifier connected from another cell. In one arragement, the outputs of two cells are connected to a differential amplifier, and the output of the differential amplifier is gain controlled by the output of a third cell.

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Saffron Walden, United Kingdom

Gillies D Pitt