The Plessey Company Plc

Plessey Overseas Limited

Clive Trundle

Jack Brettle

Ian Bennion

Stephen N Oliver

Martin J Goodwin

Harry G Heller

Rosemary Cush

Martin W Baskerville

John Whittall

Robert Glenn

Crofton J Brierley

Neil Carr

Robert Baker-Glenn

Paul J Darcy

Christopher J Groves-Kirby

William Johncock

John Whittal

Harold H Heller

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

Thin film deposition process

Reversible infra-red recording medium

Optical devices utilizing photochromic compounds

The contrast and sharpness of photoresist images is enhanced by depositing a layer of a photobleachable compound onto the photoresist layer. The photobleachable layer is sensitive to the light used to expose the photoresist and forms a contrast enhancement layer (CEL) on the photoresist layer. Fulgides and photochromic butyrolactones are selected for forming the photobleachable layer. Such compounds can be deposited from a hydrocarbon solution, such as toluene, and are soluble in the standard alkali, photoresist developers. The process is particularly advantageous for producing integrated circuits.

Contrast enhanced photolithography

Marking of articles with photochromic compounds

The invention relates to a photochromic gamma butyrolactone having the general formula (I): ##STR1## in which X represents &gt;CH.sub.2 or &gt;C(CH.sub.3).sub.2 ; R.sub.1, R.sub.2 and R.sub.4 independently represent a group selected from hydrogen, alkyl or aryl (including substituted aryl), with the proviso that one of R.sub.1 and R.sub.2 is always hydrogen, and R.sub.3 is a 3-thienyl, 3-furyl, 3-benzothienyl or 3-benzofuryl group in which the 2-position is substituted with an alkyl, aralkyl or aryl group (including substituted aryl). The lactones are useful in photolithography and in the production of security inks and markings and in the production of data recording materials.

Photochromic gamma butyrolactones

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

A series of photochromic compounds are disclosed which have the property of undergoing a reversible color change when exposed to unfiltered sunlight and reverting to their original color in the absence of U.V. light at room temperature. These compounds have the general formula: ##STR1## represents an adamantylidene or a substituted adamantylidene group;

Polychromic tetracyclo-spiro-adamatylidene derivatives, and polychromic

Growing community of inventors

Silverstone, United Kingdom

Clive Trundle