Abstract: Layer processing to grow a layer structure upon a substrate surface comprises supplying a vapor mixture stream to the substrate (28) to deposit constituents, monitoring growth with an ellipsometer (12) and using its output in real-time growth control of successive pseudo-layers. A Bayesian algorithm is used to predict a probability density function for pseudo-layer growth parameters from initial surface composition, growth conditions and associated growth probabilities therewith, the function comprising discrete samples. Weights are assigned to the samples representing occurrence likelihoods based on most recent sensor output. A subset of the samples is chosen with selection likelihood weighted in favor of samples with greater weights. The subset provides a subsequent predicted probability density function and associated pseudo-layer growth parameters for growth control, and becomes a predicted probability density function for a further iteration of pseudo-layer growth.

Abstract: This invention relates to an organic semiconductor device comprising a substrate bearing an organic layer sandwiched between electrode structures wherein the organic layer comprises a polymer of general Formula (I): wherein X is selected from H, CN, F, Cl, Br, COOCH3. Y is given by the following general Formula (II): wherein A is a phenyl group which may be further substituted in 1 or 2 or 3 positions with groups independently selected from C1-8 alkyl, CN, F, Cl; B and C are both phenyl groups which may be further substituted, independently of each other, in 1 or 2 or 3 or 4 or 5 positions with groups independently selected from C1-8 alkyl, CN, F, Cl; A, B and C may also be, independently of each other, selected from pyrimidine, pyridazine and pyridine; m=5-20,000.

Abstract: A bistable nematic liquid crystal device cell is provided with a surface alignment grating on at least one cell wall and a surface treatment on the other wall. Such treatment may be a homeotropic alignment or a planar alignment with or without an alignment direction, and zero or a non zero pretilt. The surface profile on the monograting is asymmetric with its groove height to width selected to give approximately equal energy within the nematic material in its two allowed alignment arrangements. The monograting may be formed by a photolithographic process or by embossing of a plastics material. The cell is switched by dc pulses coupling to a flexoelectric coefficient in the material, or by use of a two frequency addressing scheme and a suitable two frequency material. Polarisers either side of the cell distinguish between the two switched states. The cell walls may be rigid or flexible, and are coated with electrode structures, e.g.

Abstract: An adhesive or sealant composition comprising a compound of formula (I) provided that at least one of (a) R1 and R6 or (b) R2 and R3 or (c) R4 and R5 includes an electron withdrawing group; and where necessary, a polymerization initiator. Novel compounds of formula (I) are also described and claimed. Adhesive compositions can be used to bond for example glass and metal surfaces. Certain biocompatible adhesives for medical applications are included.

Abstract: A grating comprising a plurality of substantially parallel members having a conducting surface of depth L, separated by a dielectric layer gap, and having of pitch &lgr;g and where L>16&lgr;g. The members are preferably metallic or comprise metallic foil covered plastic. The gap may be filled wholly or partially with dielectric material including liquid crystal whose refractive index can be controlled by suitable application of voltage across the gap.

Abstract: A multi-pass optical amplifier system is provided comprising an amplifier medium (20) and at least one relay imaging telescope (18, 24) for imaging light from the amplifier medium onto a primary light directing optical component, such as a mirror (26, 29) and for imaging light directed back from a primary light directing optical component (26, 28) into the amplifier medium so that light is re-passed through the amplifier medium. The system further includes a phase conjugate mirror arrangement for intercepting light between passes for the amplifier medium to generate a phase conjugate reflection of the light incident on it. Preferably, the system is arranged such that a light beam is incident on phase conjugate mirror (22), after having passed through the amplifier medium a predetermined number of times and the phase conjugate reflection retraces the path of the incident beam.

Abstract: Liquid crystal mixtures comprising at least one of the compounds of formula (I) containing a heterocyclic five-membered ring and with a carbon-carbon double bond in the termninal group are new. RJ=CnH2n+1CH=CHCmH2mZ1; n=1-5; m=0-5; and q=0, 1 or 2; A1 and A2=2,5-disubstituted furan, 2,5-disubstituted thiophene, 2,5-disubstituted oxazole, 2,5-disubstituted thiazole, 2,5-disubstituted 1,3,4-oxadiazole, 2,5-disubstituted 1,3,4-thiadiazole, 1,4-disubstituted benzene, 2,5-disubstituted pyrimidine, 2,5-disubstituted pyridine, 2,6-disubstituted naphthalene; laterally substituted 1,4-disubstituted benzene, laterally substituted 2,5-disubstituted pyrimidine, laterally substituted 2,5-disubstituted pyridine or laterally substituted 2,6-disubstituted naphthalene (lateral substituents=F, Cl, Br or CN); A3=any A1 or 1,4-disubstituted bicyclo(2.2.

Abstract: Alignment layers for use in liquid crystal devices comprising photoactive pentaerythritol derivatives. 1,2,3,4-trakiskis(8-[2-oxo-2H-1-benzopyran-7-yloxy]octanoyloxy)pentaerythritol is but one example.

Abstract: In active semiconductor backplane (3), for example for a smectic liquid crystal cell, which comprises an array of electronic or elctrical elements in a first region (4), logic elements for addressing said array in a second region spaced from the first, and conductors coupling said first and second regions, the first and second regions are sufficiently widely spaced (21, 22) (providing a “glue lane”) to permit the presence of an adhesive sealing strip therebetween without substantial contact with the first and/or second regions, even when an opposed substrate is sealed thereto. The backplane may comprise spacers (25, 26) in the first region and/or glue lane.

Abstract: The present invention provides an avalanche photo-diode detector arrangement comprising two avalanche photo-iodes, which are each reverse biased to just below their breakdown voltage, are arranged back-to-back and are arranged in series with an oscillating voltage source such that the photodiodes exceed their breakdown voltage out of phase with each other. The oscillating voltage has a period of at least twice and preferably between 4 and 32 times, the avalanche zone transit time of the photo diodes. The detector arrangement achieves low noise and is able to distinguish dark counts.

Abstract: A method of forming three-dimensional structures on a substrate by a single reactive ion each run whereby a mask is formed on said substrate before a series of iterations are carried out, each iteration including a mask etch and a substrate etch, so that successive iterations give life to reduction in the mask area and exposure of further areas of substrate.

Abstract: An imaging system comprises an image detection unit (52) and a filter unit (58). Pixel image signals are passed in parallel from the image detection unit (52) to the filter unit (58). Circuit elements within each pixel (56) generate pixel image signal whose amplitude is proportional to the logarithm of the image intensity at that pixel. The filter unit (58) carries out a spatial filtering operation and outputs the result.

Abstract: A method of locating the source of an unknown signal of varying frequency received by receive antennas (16, 18) via relay satellites (12, 14) involves downconversion of received signals to a first intermediate frequency (IF) and band-limiting the downconverted signals. The band-limited signals are constrained to lie within a prearranged acquisition signal bandwidth by adjustment of local oscillator (LO) downconversion frequency to counteract frequency change in the unknown signal. Downconverted signals are offset in time relative to one another using trial values of differential time offset and their correlation is determined for each trial value to provide actual time offset. Compensation is provided for change in correlation phase angle, which results from signals being downconverted experiencing different LO frequencies during the time interval of the trial offset.

Abstract: A bipolar transistor having base and collector regions of narrow bandgap semiconductor material and a minority-carrier excluding base contact has a base doping level greater than 1017 cm−3. The transistor has a greater dynamic range, greater AC voltage and power gain-bandwidth products and a lower base access resistance than prior art narrow band-gap bipolar transistors.

Abstract: A method of fabricating a micro-mechanical sensor (101) comprising the steps for forming an insulating layer (6) onto the surface of a first wafer (4) bonding a second wafer (2) to the insulating layer (6), patterning and subsequently etching either the first (4) or second wafer (6) such that channels (18,20) are created in either the first (2) or second (4) wafer terminating adjacent the insulating layer (6) and etching the insulating layer (6) to remove portions of the insulating layer (6) below the etched wafer such that those portions of the etched wafer below a predetermined cross section, suspended portions (22), become substantially freely suspended above the un-etched wafer. This method uses Silicon on Insulator technology. Also disclosed is a micro-mechanical gyroscope structure (101) allowing an anisotropic silicon to be used to fabricate a sensor functioning as if fabricated from isotropic silicon.

Abstract: A recognition system (10) incorporates a filterbank analyser (16) producing successive data vectors of energy values for twenty-six frequency intervals in a speech signal. A unit (18) compensates for spectral distortion in each vector. Compensated vectors undergo a transformation into feature vectors with twelve dimensions and are matched with hidden Markov model states in a computer (24). Each matched model state has a mean value which is an estimate of the speech feature vector. A match inverter (28) produces an estimate of the speech data vector in frequency space by a pseudo-inverse transformation. It includes information which will be lost in a later transformation to frequency space. The estimated data vector is compared with its associated speech signal data vector, and infinite impulse response filters (44) average their difference with others. Averaged difference vectors so produced are used by the unit (18) in compensation of speech signal data vectors.

Abstract: Polymeric compounds of general formula (I) where X, X1, X2 are independently straight or branched chain C1-16 alkyl, halogen and H; (a) is a suitable mesogenic group; Z=single covalent bond, oxygen CO2, OCO; n=1-20; Y=oxygen, CO2, OCO, CH2, CHOH, CH2O; m=3-10,000. The compounds are liquid crystal polymers useful in liquid crystal devices, sensors, and in non-linear optical devices. The compounds are prepared by polymerization of the oxitane monomer to obtain the side-chain liquid crystalline polyoxitane compound. In this way the mesogenic groups are spaced on every fourth carbon atom in the polymer chain allowing greater mobility for the mesogenic group.

Abstract: A steerable antenna or scanner assembly (10) is connected to signal process means (12). A housing (14) surrounds a focusing antenna (16) which is stationary relative to the housing (14), a polarisation rotator (18), a steerable reflector (20) angularly movable about a pivot axis (22), and a detector (24). Incoming radiation passes through the focusing antenna (16), has its polarization altered as it passes through rotator (18), reflects off reflector (20), Passes through rotator (18) again, encounters the antenna (16) again and this time reflects off it to focus down, passes through rotator (18) again, encounters the steerable reflector (20) again and this time passes through it to reach the detector (24). Moving the reflector (20) angularly steers the directional sensitivity of the assembly (10).

Abstract: An optical analogue to digital (A/D) converter for converting an input analogue voltage signal into a digital output, comprising means for frequency modulating an optical signal with an input analogue voltage signal, delay means for splitting the frequency modulated optical signal and generating at least one differentially delayed signal and at least one reference signal, at least one combining means arranged to combine the or one of the delayed optical signals with the or one of the reference signals, and at least one converter means for converting a combined signal output from an associated one of the combining means to a digital code.

Abstract: An aerofoil wing comprising upper and lower surfaces meeting at the leading and trailing edges and a camber line representing the curvature of the aerofoil comprising at least two regions of substantially linear increases in curvature and wherein the increases in curvature are of monotonically increasing magnitude. Preferably there are three regions of substantially linear increases in curvature.