Abstract: A method of growing robust large area colloidal photonic crystals and devices produced thereby. A suspension of monosized colloidal spheres (1) is subjected to a composite shear (6) by applying a sequential set of shearing forces. The crystalline layers within the colloid experience shearing forces with components in both x and y directions, forcing the colloid into a singe face-centered-cubic structure in preference to a twinned face-centered-cubic structure. The method may also comprise the use of a dispersion medium which is capable of undergoing a controllable phase change from a liquid phase to a solid phase. The crystal may be fixed into a single face-centered cubic structure.

Abstract: A polarisation independent optical switch comprises a dielectric layer (6) in which are formed a multiplicity of minute channels (7). These channels (7) are instilled with a liquid crystal fluid, especially a nematic liquid crystal (8). Electrodes (4, 5) are formed on each side of the dielectric layer between two cell walls (2, 3). Application of a voltage across the layer results in an effective change of the refractive index of the layer, and therefore modulates the phase of light traversing the layer (6).

Abstract: A sandwich panel including a core material sandwiched between plate members, and an insert member locally replacing the core and having a profile so as to intermesh with an appropriately profiled member on the unit to which it to be connected as well as a method of connecting sandwich panels by inserting an insert member having a profiled side so as to interlock with an appropriately profiled member on the unit to which it is to be connected.

Abstract: Protective casing (10) for electrical equipment which is to be deployed in a hazardous environment comprises a main body portion (12, 14) and one or more protective cages each comprising at least one annulus (20A) surrounding the main body portion and attached thereto by two or more spoke members (20). The invention provides casing which conforms to applicable standards whilst being simple and inexpensive to manufacture.

Abstract: A vertical cavity surface emitting laser (VCSEL) comprising a one dimensional grating structure configured to act as a waveguide, preferably located at an end surface of the VCSEL, for selectively reflecting more of a first polarisation of light back into the cavity of the VCSEL than a second orthogonal polarisation of light. Preferably the VCSEL comprises an upper Bragg mirror, a gain region, and a lower Bragg mirror, and the one dimensional grating structure is located on a top layer of the upper Bragg mirror and the top layer of the upper Bragg mirror has a thickness such that the reflected light of one polarisation constructively interferes with light of said one polarisation which is reflected by the upper Bragg mirror. The VCSEL will then lase at the polarisation which is more predominantly reflected by the grating structure.

Abstract: A method for compensation for object motion during scan, especially an magnetic resonance imaging (MRI) scan is provided. The method involves taking a first data set corresponding to a first focussed image and adding a number of data points to form a sligthly higher resolution image. The first data set is then used to predict what the next data points would be. The prediction can be performed in k-space, image space or in a hybrid space. The predicted data points arm then compared with the actual data points acquired as a means of determining any displacements. The displacements may be determined by comparing the phases of the actual and predicted data points and the k-space data corrected to compensate for any detected motion.

Abstract: The present invention relates to an impact ionisation avalanche transit time (IMPATT) diode device comprising an avalanche region and a drift region, wherein at least one narrow bandgap region, with a bandgap narrower than the bandgap in the avalanche region, is located adjacent to or within the avalanche region in order to generate within the narrow bandgap region a tunnel current which is injected into the avalanche region. This improves the predictability with which a current can be injected into the avalanche region and enables a relatively narrow pulse of current to be injected into the avalanche region in order to enable a relatively noise free avalanche multiplication. The narrow bandgap region may be located between a heavily doped contact region and the avalanche region and is preferably arranged to generate a tunnel current at the peak reverse bias applied to the diode.

Abstract: An extracting transistor (10)—an FET—includes a conducting channel extending via a p-type InSb quantum well (22) between p-type InAlSb layers (20, 24) of wider band-gap. One of the InAlSb layers (24) incorporates an ultra-thin n-type &dgr;-doping layer (28) of Si, which provides a dominant source of charge carriers for the quantum well (22). It bears n+ source and drain electrodes (30a, 30b) and an insulated gate (30c). The other InAlSb layer (20) adjoins a barrier layer (19) of still wider band-gap upon a substrate layer (14) and substrate (16) with electrode (18). Biasing one or both of the source and drain electrodes (30a, 30b) positive relative to the substrate electrode (18) produces minority carrier extraction in the quantum well (22) reducing its intrinsic contribution to conductivity, taking it into an extrinsic saturated regime and reducing leakage current.

Abstract: A micro air vehicle is propelled by a bipropellant micro engine supplied with hydrogen peroxide and a hydrocarbon fuel. The hydrogen peroxide is decomposed to produce steam and oxygen at high temperature and the hydrocarbon fuel is burnt within a combustion chamber with oxygen produced from such decomposition. Products of such decomposition and combustion are exited through a nozzle to produce thrust. In a preferred embodiment there is also a ducted turbofan located downstream of the nozzle exit.

Abstract: A source localising method comprises the steps of measuring the power received by a set of sensors and selecting N measurements from respective sensors, where N is an even number and at least four. N−1 different direct power ratios are constructed each derived from the N power measurements, with different numerators and denominators derived from respective halves of the measurements in each case. The construction of N−1 direct power ratios is facilitated by the use of a suitably constructed Hadamard matrix. Each direct power ratio may be converted with a logarithmic transformation into a linear combination of measured powers.

Abstract: An apparatus for detecting ferromagnetic objects in the vicinity of a magnetic resonance imaging scanner. The apparatus comprises primary sensor means adapted to measure a magnetic field, arranged in communication with signal processing means configured to identify temporal variations in the measured magnetic field due to the movement of a ferromagnetic object within an ambient magnetic field and to provide an output indicative of the presence of a ferromagnetic object in the vicinity of the primary sensor means. The apparatus further comprises secondary, non-magnetic, sensor means adapted to detect the movement of objects in the vicinity of the primary sensor means in order to reduce false alarms. The output from the signal processing means may be used to operate an audible alarm, a visual alarm, an automatic door lock or a physical barrier.

Abstract: Relates to writing an array of optical elements which are each switched between two states according to input data sets. In a first method, data is written in two steps in which different selected elements are respectively driven to one binary state and the other binary state. The selected elements of the two sets may be complementary, but are preferably only those which are required to change from their existing state. The latter criterion may be used in an alternative method using a single addressing of the array to turn elements in either direction as required. In a further method, as shown, selected elements only of a blank array are written in a first WRITE step so as to correspond with a set of data, and in a subsequent second ERASE step the selected elements are selectively erased to restore a blank array prior to writing and erasing another set of data. The methods have particular utility for maintaining a dc balance at pixels of a liquid crystal array.

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 polymerisation 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 quantum wire field-effect transistor having at least one, one-dimensional, elongate conducting means (14) provided by at least a first semiconductor layer surrounded by a wider bandgap, second semiconductor layer (12, 13) and extending between source (24) and drain (26) electrodes, and in which there is provided a backgate structure (8, 23) to control conduction in the elongate conducting means. The transistor can be a Single Electron Transistor (SET) wherein two adjacent gate electrode (16, 18) are disposed over the elongate conducting means to induce a quantum dot (17) therein, and it can be made with the first semiconductor layer material as GaAs and the second semiconductor layer material as AlGaAs. A method of making the transistor involves preferentially growing the elongate conducting means at the bottom of a groove (6) lined with second semiconductor layer (12).

Abstract: A multilayer surface comprising at least two layers, said layers having different refractive indexes such that selective wavelengths/colours are transmitted and or reflected. The layers are preferably laid onto a transparent substrate. The surface can be used as an anti-counterfeit device. A method of determining whether an article is counterfeit comprising: providing such a surface; determining its transmission/absorption characteristics of particular colour(s); matching these up with the expected characteristics to determine whether the surface is counterfeit. This may comprise observing the reflected or transmitted colour at two different angles of incidence or detecting changes in the polarisation state of transmitted light.

Abstract: An integrating magnetic sensor is described which comprises a sensor element made from a filament of substantially amorphous material which exhibits giant magneto-impedance and means for applying a bias field to the said sensor element so that it operates in the high field section of the giant magneto-impedance response.

Abstract: A compound lens arrangement for use in an array of such lens arrangements comprising at least two lens elements including a front lens element having a front lens surface which is the largest diameter lens surface in the compound lens arrangement, wherein the exit pupil of the compound lens is bounded by and lies in the plane of the edge of said front lens surface. This enables the compound lens arrangements in an array to abut. The invention particularly relates to compound lens arrangements for use in projectors which projectors are used in an array in an autostereo projection system and allows adjacent projectors to abut.

Abstract: A method of manufacture of a ceramic material comprises the steps of preparing a melt of the ceramic materials, cooling the melt slowly through the freezing point of the material to initiate solidification, holding the melt at a temperature below the freezing point of the material whilst solidification progresses and characterised in that during solidification an ultrasonic field is applied to the melt. The melt composition may be selected to include an excess of one or more ceramic materials so as to produce a second phase dispersed in the solidified product during solidification. Also claimed is a ceramic material produced by the method described. The ceramic material may be a superconductor.

Abstract: A process for the production of a lithium transition metal sulphide such as lithium iron sulphide, the process comprising reacting a transition metal sulphide with lithium sulphide in a solvent comprising molten sulphur. Lithium transition metal sulphides obtained using this process are also claimed and are useful in the production of electrodes, in particular for rechargeable lithium batteries.

Abstract: A multi-layer Auger suppressed diode having at least two exclusion interfaces and at least two extraction interfaces. A specific embodiment has two composite contacts, each consisting of a heavily doped layer (3, 4) and a buffer layer (8, 9) of lower doped, high bandgap material sandwiched between the heavily doped layer and the active region (2) of the device.