Abstract: A method of establishing a quantum key for use between a first network node (QNode1) and a second network node (QNode3) in a network for carrying out quantum cryptography includes a key agreement step carried out by a third node (QNode2) and the second node (QNode3) and a subsequent authentication step carried out by the first and second nodes directly. As the key agreement step does not involve QNode1, another key agreement step may be simultaneously performed by another pair of network nodes QNode4, QNode5 to agree a quantum key for use by network nodes QNode1 and QNode5. The invention allows respective quantum keys to be established between a network node and each of a set of other nodes more rapidly than is the case if each quantum key is established serially by key agreement and authentication steps.

Abstract: Demodulation apparatus for demodulating phase-modulated signals comprises a quadrature signal generator (QSG) for generating in-phase (I) and quadrature-phase (Q) signals in response to an unmodulated input signal. The QSG provides fast frequency tracking of the input signal and excludes any high-frequency content the input signal.

Abstract: A method of manufacture of cadmium mercury telluride (CMT) is disclosed. The method involves growing one or more buffer layers on a substrate by molecular beam epitaxy (MBE). Subsequently at least one layer of cadmium mercury telluride, Hg1-xCdxTe where x is between 0 and 1 inclusive, is grown by metal organic vapour phase epitaxy (MOVPE). The use of MBE to grow buffer layers allows a range of substrates to be used for CMT growth. The MBE buffer layers provide the correct orientation for later MOVPE growth of CMT and also prevent chemical contamination of the CMT and attack of the substrate during MOVPE. The method also allows for device processing of the CMT layers to be performed with further MOVPE growth of crystalline CMT layers and/or passivation layers. The invention also relates to new devices formed by the method.

Abstract: In coded aperture imaging knowledge of the coded array pattern and its positional relation to the detector array is needed in order to be able to reconstruct the scene image. Usually a theoretical model of the coded array is used and the actual array needs to be aligned accurately with respect to the detector. The present invention uses a coded aperture imager to image a reference object in the scene and uses the intensity pattern on the detector array to determine the decoding pattern corresponding to the coded aperture array. The reference object may be a point source in which case the pattern on the detector array may be used directly as the decoding pattern or it may be used to correct a theoretical pattern for any misalignment.

Abstract: A method for evaluating a composite structure includes providing a model of said structure and locally varying a material property to determine complex reflection and transmission coefficients at said locality. From these coefficients at least one ultrasonic response characteristic for said material property can be found and compared to a measured ultrasonic response of a sample to determine a local measure of the material property. This method exploits the fact that certain material properties contribute to the ultrasonic frequency response substantially independently of one another. The frequency response of a region of porosity and of a thick resin layer in particular are evaluated. In one embodiment, the modelled responses are used to provide frequency domain basis functions for material properties, which can in turn be used in a decomposition method.

Abstract: A method of manufacturing a shaped part, the method including: (I) providing a partially consolidated porous part that has been made from a powder; (II) permeating the porous part with a volatile liquid (e.g. water, ethanol), so that the liquid is present in the pores of the porous part; and (V) forming the shaped part by applying a laser beam to a spot on the surface of the liquid-permeated part to cause the volatile liquid to heat in the spot region, causing the powder particles to separate in the spot region, so that a portion of the part is ablated in the spot region. The porous part may be made from metallic or ceramic powder and has been partially consolidated for integrity, but is ablated by this lower energy, liquid-assisted laser process, prior to further strengthening. The method allows bespoke, complex shaped parts such as aerospace parts or medical implants to be made inexpensively, especially shaped titanium parts.

Abstract: The invention relates to methods and apparatus for Quantum key distribution. Such methods including authenticating a first node in a communications network with a remote node in the communications network. The authentication may include connecting an authentication device to the first node, agreeing a quantum key between the first node and the remote node based on a quantum signal transmitted or received by the first node and performing an authentication step between the authentication device and the remote node on an encrypted channel. Authentication between the authentication device and remote node may be taken as authentication of the first node.

Abstract: The invention relates generally to an electro-optic identification device, particularly to a helmet-mounted identification device. An identification device suitable for mounting on an object comprises a support structure having a plurality of electro-optic emitters positioned thereon, wherein the support structure conforms, in use, to the shape of said object. Preferably, the support structure takes the form of a plurality of emitter arms radiating from a hub, each arm comprising one or more electro-optic emitters. The electro-optic emitters may include visible emitters and/or infrared emitters, and are more preferably selected from the group consisting of near infrared emitters, medium wave thermal infrared emitters and long wave thermal infrared emitters, or any combination thereof. The invention has particular utility in military applications.

Abstract: A random access decoder comprising a plurality of decoder circuit elements, each decoder circuit element having a unique electronic address and a binary data output, means for applying an input signal to each of the decoder circuit element and where each decoder circuit element places data on its binary data output only when the unique electronic address of a particular decoder circuit element matches the applied input signal and wherein the unique electronic address of each of the plurality of decoder circuit elements is electronically loaded into each of the decoder circuit elements. In one embodiment, each decoder circuit element comprises equivalent components electrically connected in the same arrangement.

Abstract: An oil and gas well shaped charge perforator is provided comprising a housing, a high explosive, and a liner with a further insert liner where the high explosive is positioned between the liner and the housing. In use the high explosive will collapse the liner and insert causing two cutting jets to form. The insert may substantially cover the surface area of the liner or it may over only partially cover the liner, such as the apical portion of the liner or the base portion of liner. Alternatively the insert may be varied in thickness across the surface area of the liner. Typically the thickness of the liner may be between 1 and 10% of the liner diameter and the thickness of the insert may be between 1 and 200% of the thickness of the liner. The insert may be produced during the manufacture of the liner, but preferably the liner will be a retro fitted item.

Abstract: A frequency modulated continuous wave (FMCW) radar is described. The radar includes a first discriminator for receiving a portion of the swept frequency signal generated by a frequency sweep generator and for producing a reference difference-frequency signal of frequency equal to the difference between the frequency of the swept frequency signal and the frequency of a time displaced swept frequency signal derived from the swept frequency signal. An analogue-to-digital converter is provided for sampling the target difference-frequency signal at a rate derived from the frequency of the reference difference-frequency signal. A processor (88) for determining frequency components of the digitized target difference-frequency signal is arranged to determine for at least one frequency component of the digitized target difference-frequency signal any phase difference between frequency sweeps of said swept frequency signal. The radar may be used for detecting foreign object debris (FOD) on runway surfaces and the like.

Abstract: A millimeter wave imaging apparatus and method capable of identifying the presence of relatively thin dielectric materials is disclosed. The method involves taking a plurality of millimeter wave images of a scene at different frequencies and analyzing the images at different frequencies to look for frequency dependent effects in the scene. Relatively thin dielectric materials can lead to interference effects which can be detected. In one embodiment the imaging apparatus comprises a millimeter wave imager (2) connected to a processor (16) and at least one variable frequency illumination source (22a . . . d, 24a . . . d). The or each illumination source sweeps the illumination frequency across a reasonably wide bandwidth and the imager captures radiation returned from the scene at a number of different illuminating frequencies.

Abstract: A method is provided for the synthesis of a mesoporous lithium transition metal compound, the method comprising the steps of (i) reacting a lithium salt with one or more transition metal salts in the presence of a surfactant, the surfactant being present in an amount sufficient to form a liquid crystal phase in the reaction mixture (ii) heating the reaction mixture so as to form a sol-gel and (iii) removing the surfactant to leave a mesoporous product. The mesoporous product can be an oxide, a phosphate, a borate or a silicate and optionally, an additional phosphate, borate or silicate reagent can be added at step (i). The reaction mixture can comprise an optional chelating agent and preferably, the reaction conditions at steps (i) and (ii) are controlled so as to prevent destabilisation of the liquid crystal phase. The invention is particularly suitable for producing mesoporous lithium cobalt oxide and lithium iron phosphate.

Abstract: An optical routing device is described that comprises a semiconductor substrate (52) having at least one optical input (4), a plurality of optical outputs (6,8) and an array of MEMS moveable reflective elements (58;102). The array of moveable reflective elements (58;102) are configurable such that light can be selectively routed from any one optical input (4) to any one of two or more of said plurality of optical outputs (6,8). Light selectively routed from any one optical input to any one of two or more of said plurality of optical outputs (6,8) is guided within a hollow core waveguide (54). In one embodiment, a cross-connect optical matrix switch is described.

Abstract: Apparatus for the wireless transmission of data, and preferably also of power, across a space between a length of production tubing and a surrounding casing in a petrochemical well, includes a pair of inductively-coupled coils, a first of which is located on the exterior of the production tubing generally coaxially therewith, and the second of which is located on the interior of the casing generally coaxially therewith. This may be used in particular as part of a system for transmitting power and data to/from a sensor monitoring the pressure and/or other environmental conditions within the “B” annulus B of a sub-sea well.

Abstract: A tip device to act as an outboard continuation of an aircraft wing or other aerodynamic lifting surface has a downward cant angle, a leading edge swept back in relation to the leading edge of the inboard lifting surface, and a chord reducing in the outboard direction of the device. A favourable balance between induced drag reduction and increased wing root bending moment can thereby be achieved. Preferably the device also has an upwardly canted portion at its root end so that the downward cant commences from a relatively elevated spanwise location, thereby alleviating any ground clearance problems.

Abstract: A micro-opto-electro-mechanical systems (MOEMS) electro optical modulator (2) having an electrically tuneable optical resonator comprising an asymmetric Fabry-Perot etalon incorporating a mirror (10) resiliency biased with respect to a substrate (13) and moveable in relation thereto in response to a voltage applied there-between. The optical modulator (2) is capable of modulating electromagnetic radiation having a plurality of wavelengths. The modulator is adapted to modulate the transmission of short wave infrared radiation (SWIR), medium wave infrared radiation (MWIR) and long wave infrared radiation (LWIR) and the reflection of visible radiation. A spatial optical modulator having a plurality of said MOEMS optical modulators (2). A method of addressing said spatial optical modulator.

Abstract: A method for monitoring a fluid carrying conduit by introducing an acoustic pulse into the conduit, and interrogating an optic fibre positioned along the path of said conduit to provide distributed acoustic sensing. By measuring the response at each of a plurality of locations, a conduit condition profile can be derived. A condition profile can be obtained quickly and easily with minimum disruption to the pipeline infrastructure and contained flow. Existing optic fibres running along the path of a pipe can be employed for sensing purposes, allowing relatively long spans of pipeline to be monitored with only limited access to the pipe.

Abstract: A thermally emissive apparatus (2) having an electro-thermal heating element (6) comprising a layer (8) of a first material having a first resistivity and a plurality of discrete regions (10) of a second material having a second resistivity substantially lower than that of the first material in electrical contact with the first material. The plurality of regions (10) of second material are arranged spatially so as to impart a predetermined effective sheet resistivity to the first layer (8). A plurality of heating elements may be used having a common first layer (30) of first material, wherein the spatial arrangement of the regions (10) of second material within a first heating element are optionally different to that within a second heating element. In this configuration the first and second heating elements may emit infrared radiation (14) having different intensities. The apparatus (2) finds applications as a thermal target and as an electro-thermal ice protection device.

Abstract: A laser radar device adapted to ensure that the output from the laser is eye-safe. A means for applying spatial dither to the output of the laser source, such as a moveable optical arrangement. This causes the point of focus of the transmitted beam to traverse a target area by small amounts, reducing the overall radiation exposure at any particular point of focus, but having negligible impact on wind speed measurement for example. Alternative arrangements for ensuring eye-safety include periodically reducing the laser power density, gating the output or altering the focussing of the transmitted beam.