Abstract: A photodetector circuit incorporates an APD detector structure (10) comprising a p? silicon handle wafer (12) on which a SiO2 insulation layer (14) is deposited in known manner. During manufacture a circular opening (16) is formed through the insulation layer (14) by conventional photolithography and etching, and an annular p+ substrate contact ring (18) is implanted in the handle wafer (12) after opening of the window (16). The APD itself is formed by implantation of a p region (20) and an n+ region (22). After the various implantation steps a metallisation layer is applied, and annular metal contacts are formed by the application of suitable photolithography and etching steps, these contacts comprising an annular contact (26) constituting the negative terminal and connected to the p+ substrate contact ring (18), an annular metal contact (28) constituting the positive terminal and connected to the n+ region (22) of the APD, and source and drain contacts (30) and (32) (not shown in FIG.

Abstract: A device for the generation of electrical power from a fluid flow, and more particularly for harvesting power from flows downhole in oil or gas wells, comprises a cylinder or other blunt body (1) arranged crosswise to the flow and supported on the end of a sprung cantilever arm (3) held in a fixed mount, with freedom to oscillate in response to the shedding of a Karman vortex trail v from the? body. The resultant motion of the body (1) and arm (3) is converted into electrical energy by piezoelectric material (5) which is attached to, and stressed by, flexure of the arm. Other arrangements of piezoelectric and inductive power generation from the oscillation of the device are described.

Abstract: Apparatus for classifying objects in an input waste stream comprises a hyperspectral sensor, means for moving objects in the input waste stream relative to the sensor and through a sensing region thereof, and processing means for classifying objects in the input waste stream on the basis of signals output from the hyperspectral sensor to the processing means. The apparatus allows classification of objects composed of one of a wide range of materials and also provides for discrimination of objects comprising different grades of the same material.

Abstract: A surface (30) suitable for promoting the formation of droplets of liquid (35) is provided comprising alternating regions of liquid repelling (32) and liquid attracting (33) material in at least one direction across the surface wherein the diameter of the droplets is controlled by the size of the smallest dimension of the liquid attracting material. The surface (30) may be textured and/or form a pattern. Also disclosed are a method and a system of collecting a liquid (35) carried by or condensed out of a vapour comprising passing a vapour across such a surface (30) and a method of purifying a liquid by passing a vapour containing droplets of a liquid over such a surface.

Abstract: Methods and apparatus for ensuring the computer security of users of a computer system are described. A user is allocated a security grading relating to how secure their computer system (2) is, for instance in terms of anti-virus software, firewalls and up-to-date security patches. Methods and apparatus (10, 12) for providing a security grading of a user's computer system are also disclosed. Users without a security grading or with low level security grading may then be accorded only basic access to the data or functionality of another computer system (8), for instance such as on-line banking services or the like. This ensures therefore that those users that take responsibility for their own security are allowed full access without undue security protocols whereas users without proper security do not have so much access.

Abstract: A scanning imaging apparatus comprises an optical system including a curved polariser/reflector, a rotatable reflector, a polarisation twisting plate, and a receiver array, wherein a convex reflective element is incorporated in the optical path that acts as a sub-reflector that increases the optical system focal length. It has been found that an increase to the optical focal length in this manner gives a greater 3 dB spot size at the image plane, thus easing design constraints on the receiver array packing density, whilst maintaining a given spatial sampling interval. An additional benefit is that radiation from differing scan locations diverges as it approaches the image plane, which provides more volume in which to position receiver electronics. Focussing of the optical system may be achieved by movement of the sub-reflector.

Abstract: The present invention relates to an imaging apparatus and comprises input and output polarisers, a first polarising beam splitter and at least one additional polarising beam splitter, a light sensitive detector and focussing means arranged on an axis. The input polariser resolves incident light into a single linear polarisation state. The first polarising beam splitter receives light from the input polarises, and resolves it into equal magnitude orthogonally polarised rays which are mutually spaced and have a path difference therebetween. The or each additional polarising beam splitter is arranged to receive light from the first polarising beam splitter. The transmission axis of the output polariser is parallel to or perpendicular to the transmission axis of the input polarises to resolve the orthogonally polarised light rays having past through the or each additional polarising beam splitter into the same or perpendicular polarisation state as light resolved by the, first polariser.

Abstract: An optical sensor assembly comprising a plurality of optical fibre sensor coils optically coupled by optical fibre; and an elongate support element, on which said plurality of optical fibre sensor coils and optically coupling optical fibre are mounted is disclosed. The support element has an elastic limit such that when said support element is bent from the elongate axis, the optical fibre fracture limit is reached before the elastic limit is reached. An array of these optical sensor assemblies, the mandrel on which the sensing coils are mounted and their method of manufacture are also disclosed.

Abstract: A detection system operable at millimetre or sub-millimetre wavelengths includes detection means adapted to detect radiation at two distinct wavebands, wherein a first waveband is chosen such that it has a relatively high atmospheric absorbency to electromagnetic radiation, and the second waveband is chosen to have a relatively low atmospheric absorbency to electromagnetic radiation. The system is further adapted to take measurements from at least two different regions on a target, and to process the measurements to give an indication that the target contains an object of interest. The processing may comprise comparing measurement differences at a given waveband to reference data obtained from test measurements, or from computer models of targets. The detection system provides the ability to detect objects of interest without the need to provide a millimetric or sub-millimetric image of the target.

Abstract: A photonic light circuit device is described that comprises a semiconductor substrate (220) and two or more optical components (226, 228, 236, 240) wherein one or more hollow core optical waveguides (230, 232, 224) are formed in the semiconductor substrate to optically link said two or more optical components. The PLC may comprise a lid portion (44) and a base portion (42). The PLC can be adapted to receive optical components (8:608) or optical components may be formed monolithically therein. Coating with a reflective layer is also described.

Abstract: A phased array antenna (400) comprises a first array element (402) and second array element (404) and a dielectric separator (408). Each of the first and second array elements (402,404) is a detection element and or an emitter element. The dielectric separator (408) is located between the first and second array elements (402, 404) and within a path of an inter-element mutual coupling (IMC) signal between the first array element (402) and the second array element (404).

Abstract: A relief structure alignment layer comprising a relief structure surface incorporating at least one indentation, the at least one indentation having an internal surface extending from the relief structure surface, wherein the relief structure alignment layer has a surface memory alignment layer arranged to impart a preferred liquid crystal director alignment to a liquid-crystal material in contact therewith as well as methods for configuring a liquid crystal material within a cell having a relief structure alignment layer by applying at least one of an electric field and a magnetic field and phoretic displays comprising at least on relief structure alignment layer.

Abstract: A phased array antenna system with controllable electrical tilt generates two signals V2a and V2b with variable relative delay therebetween. The signals are converted into antenna element drive signals by a power distribution network. The network splits each of the two signals V2a and V2b into three signal components. Pairs of components of different signals are input respective hybrid coupling devices (hybrids), which provide vector sums and differences of their inputs and act as phase-to-power converters. Their outputs are distributed between further hybrids, which act as power-to-phase converters and provide antenna element drive signals with phase varying both with element array position and also with the variable relative delay between the two signals V2a and V2b. Antenna electrical tilt is therefore controllable by altering a single relative delay.

Abstract: An electromagnetic radiation absorber for absorbing radiation in the wavelength range ?min to ?max. The absorber has a conductor layer in contact with a dielectric layer. The conductor layer carries a plurality of apertures of sub-wavelength dimension and the thickness of the absorber is less than ?min/4n, where n is the refractive index of the dielectric. The dielectric layer may be sandwiched between two conductor layers, one of which has the structure described above. The invention is also directed to various articles comprising such an absorber.

Abstract: An electronic safety and arming unit comprises a micro electromechanical system (MEMS) shutter device. The shutter (18) is suspended by thin lightweight arms and hinges, all formed by silicon processing of SOI substrates and includes holding latches for holding the shutter (18) in the closed position. The holding latches may be released by an electrothermal actuator. The shutter (18) separates an initiator section from an explosive train (6) of munitions such as shells, thereby providing safety until the shell is fired and away from its start point. After firing, the shutter (18) is opened ready for the main explosive to be detonated by the initiator (3). The shutter (18) may be suspended by a compliant displacement multiplier and may include an electrothermal actuator such as an electrically heatable bent beam. Heating of the beam causes movement of a shutter blade from a shut condition covering a firing aperture to an open condition.

Abstract: A metal detection apparatus includes a transmitter for generating a magnetic field in the vicinity of the metal object, and a detector for detecting a secondary magnetic field. The detector include a first gradiometer for providing a first output signal representative of a first direction, y, to the metal object, a second gradiometer arranged substantially orthogonal to the first gradiometer for providing a second output signal representative of a second direction, x, to the metal object, the second direction being substantially orthogonal to the first direction and in the same plane as the first direction, and an outer coil and an inner coil arranged to be substantially concentric with one another and each of which is arranged to provide an output signal representative of secondary magnetic field strength in a third direction, z, which is substantially orthogonal to the plane of the first and second directions.

Abstract: A surface (30) suitable for promoting the formation of liquid (35) is provided comprising alternating regions of liquid repelling (32) and liquid attracting (33) material in at least one direction across the surface wherein the diameter of the droplets is controlled by the size of the smallest dimension of the liquid attracting material. The surface (30) may be textured and/or form a pattern. Also disclosed are a method and a system of collecting a liquid (35) carried by or condensed out of a vapour comprising passing a vapour across such a surface (30) and a method of purifying a liquid by passing a vapour containing droplets of a liquid over such a surface.

Abstract: The invention relates to a method of multiple criteria decision making. In particular, a method of maintaining a complex article is described that includes the steps of; (a) taking a set of options for replacing each of a plurality of components of the complex article, (b) identifying an optimum solution set from the set of possible replacement options of step (a) that best satisfies a plurality of criteria and (c) implementing an optimum solution of the optimum solution set. The step of identifying an optimum solution set comprises the step of evaluating a plurality of potential solutions from the set of possible options defined in step (a) against the plurality of criteria.

Abstract: Computer system protection to protect against harmful data from an external computer network (60) (e.g. the Internet) involves supplying incoming data (62) to a software checker (64) as the data enters a computer system (not shown). The checker (64) routes any suspect data (66) to an encryptor (68) which encrypts it to render it unusable and harmless. Encrypted data passes to a computer (72) in an internal network (74) and having a desktop quarantine area or sandbox (76) for suspect data. The computer (72) runs main desktop applications (78) receiving encrypted data (70) for storage and transfer, but not for use in any meaningful way because it is encrypted. Equally well applications (78) cannot be interfered with by encrypted data (70) because encryption makes this impossible. On entry into the sandbox (76), the encrypted data (70) is decrypted to usable form it then becomes accessible by software (204) suitable for use in the sandbox (76) subject to sandbox constraints.

Abstract: A coherent differential absorption lidar (DIAL) device 2 comprises a transmit portion 4 for directing a combined light beam to a remote target and a receive portion 5 for receiving light returned from the remote target and for coherently mixing the received light with its associated local oscillator beam. The combined beam comprises at least two component light beams of discrete wavelengths. The device further comprises a signal correction means. The signal correction means comprising a means for extracting a portion of each component light beam from the transmit portion, a means for introducing a frequency difference 62 between each extracted component light beam and its associated local oscillator beam and a means for directing the extracted beam into the receive portion. This provides an additional correction signal thereby improving device performance.