Plessey Overseas Limited

The Plessey Company Plc

Jack Brettle

Clive Trundle

Ian Bennion

Kevin J Lodge

Martin J Goodwin

Harry G Heller

Stephen N Oliver

John Whittall

Christopher J Groves-Kirkby

Martin W Baskerville

William G Howell

Neil Carr

Martin T Goosey

Simon M Hughes

Nicholas J Loggie

Robert Baker-Glenn

Robert Glenn

A method of forming optical waveguides is described in which a film of a novolac resin is deposited on a transparent substrate and a dopant material is incorporated into the film during or after the coating step. Additional quantities of the same or different dopant may be incoporated into the dried film by solvent assisted indiffusion.

Doped polymer films for waveguides

Optical data storage

Marking of articles with photochromic compounds

Organic optical waveguides and method of fabricating waveguide structures

Photoreactive plastics lenses are disclosed which are coated or impregnated with an adamantane 2-spiro-benzo or naphthopyran and with a blue coloring photochromic benzo- or naphthopyran having a nitrogen containing substituent in the 2-position in the pyran ring. The lenses darken in sunlight and fade rapidly at ambient temperatures in the dark or in white light which does not contain a U.V. component. The combination of the yellow/orange coloring adamantane 2-spiro pyran compound with the purple/blue coloring pyran gives a desired brown/grey coloration in the sunlight-darkened lens. The invention includes novel blue-coloring pyran compounds in which the nitrogen-containing substituent in the 2-position is a phenyl group having an amino or substituted amino or nitrogen-containing heterocyclic substituent in the ortho- or para-position of the phenyl group. The basic chromene structure and the suffix N will be used to distinguish the blue-coloring pyran compounds having a nitrogen-containing substituent, namely: ##STR1##

Photoreactive lenses with adamantane spiro compounds

Irreversible photochromic markings

The plastic encapsulation material covering an integrated circuit is impregnated with a corrosion inhibitor evenly dispensed throughout the material. This inhibits the corrosion of the metallization on the surface of the integrated circuit thus prolonging the life of the device particularly under adverse environmental conditions.

Plastics encapsulated electronic devices

Small lengths of conductors, cut to the appropriate size are used as radar 'chaff' or passive reflectors to give spurious returns on an enemy radar and thereby act as an electronic countermeasure. Currently used chaff includes chopped aluminum foil, aluminum coated glass fibres and silver coated nylon monofilaments. Current radars operate in the 10.sup.10 Hz region and current chaff dipoles are of centimetric size, but future radar systems are likely to operate at higher frequencies requiring shorter dipoles lengths to achieve an increased packing density the dipoles also need to be thinner. Carbon fibres have advantages over existing chaff materials as they are fine, light and much stiffer than existing chaff materials. The electrical resistance is about 1000.times.higher than that of aluminum however and this invention therefore proposes the use of carbon fibres coated with a much more conductive coating. Typical coating materials can be copper, silver aluminium applied by a number of different methods.

Radar wave dipole of copper coated carbon fibers

A conductive gasket for use in electro magnetic interference protection of electrical apparatus comprises an elastomeric material in which high aspect ratio conductive fibres are embedded to provide the conductive paths across the gasket. Preferably the fibres are carbon fibres.

Conductive gaskets

Growing community of inventors

Greens Norton, United Kingdom

Jack Brettle